cse.c revision 90075
190075Sobrien/* Common subexpression elimination for GNU compiler. 290075Sobrien Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998 390075Sobrien 1999, 2000, 2001, 2002 Free Software Foundation, Inc. 490075Sobrien 590075SobrienThis file is part of GCC. 690075Sobrien 790075SobrienGCC is free software; you can redistribute it and/or modify it under 890075Sobrienthe terms of the GNU General Public License as published by the Free 990075SobrienSoftware Foundation; either version 2, or (at your option) any later 1090075Sobrienversion. 1190075Sobrien 1290075SobrienGCC is distributed in the hope that it will be useful, but WITHOUT ANY 1390075SobrienWARRANTY; without even the implied warranty of MERCHANTABILITY or 1490075SobrienFITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1590075Sobrienfor more details. 1690075Sobrien 1790075SobrienYou should have received a copy of the GNU General Public License 1890075Sobrienalong with GCC; see the file COPYING. If not, write to the Free 1990075SobrienSoftware Foundation, 59 Temple Place - Suite 330, Boston, MA 2090075Sobrien02111-1307, USA. */ 2190075Sobrien 2290075Sobrien#include "config.h" 2390075Sobrien/* stdio.h must precede rtl.h for FFS. */ 2490075Sobrien#include "system.h" 2590075Sobrien 2690075Sobrien#include "rtl.h" 2790075Sobrien#include "tm_p.h" 2890075Sobrien#include "regs.h" 2990075Sobrien#include "hard-reg-set.h" 3090075Sobrien#include "basic-block.h" 3190075Sobrien#include "flags.h" 3290075Sobrien#include "real.h" 3390075Sobrien#include "insn-config.h" 3490075Sobrien#include "recog.h" 3590075Sobrien#include "function.h" 3690075Sobrien#include "expr.h" 3790075Sobrien#include "toplev.h" 3890075Sobrien#include "output.h" 3990075Sobrien#include "ggc.h" 4090075Sobrien 4190075Sobrien/* The basic idea of common subexpression elimination is to go 4290075Sobrien through the code, keeping a record of expressions that would 4390075Sobrien have the same value at the current scan point, and replacing 4490075Sobrien expressions encountered with the cheapest equivalent expression. 4590075Sobrien 4690075Sobrien It is too complicated to keep track of the different possibilities 4790075Sobrien when control paths merge in this code; so, at each label, we forget all 4890075Sobrien that is known and start fresh. This can be described as processing each 4990075Sobrien extended basic block separately. We have a separate pass to perform 5090075Sobrien global CSE. 5190075Sobrien 5290075Sobrien Note CSE can turn a conditional or computed jump into a nop or 5390075Sobrien an unconditional jump. When this occurs we arrange to run the jump 5490075Sobrien optimizer after CSE to delete the unreachable code. 5590075Sobrien 5690075Sobrien We use two data structures to record the equivalent expressions: 5790075Sobrien a hash table for most expressions, and a vector of "quantity 5890075Sobrien numbers" to record equivalent (pseudo) registers. 5990075Sobrien 6090075Sobrien The use of the special data structure for registers is desirable 6190075Sobrien because it is faster. It is possible because registers references 6290075Sobrien contain a fairly small number, the register number, taken from 6390075Sobrien a contiguously allocated series, and two register references are 6490075Sobrien identical if they have the same number. General expressions 6590075Sobrien do not have any such thing, so the only way to retrieve the 6690075Sobrien information recorded on an expression other than a register 6790075Sobrien is to keep it in a hash table. 6890075Sobrien 6990075SobrienRegisters and "quantity numbers": 7090075Sobrien 7190075Sobrien At the start of each basic block, all of the (hardware and pseudo) 7290075Sobrien registers used in the function are given distinct quantity 7390075Sobrien numbers to indicate their contents. During scan, when the code 7490075Sobrien copies one register into another, we copy the quantity number. 7590075Sobrien When a register is loaded in any other way, we allocate a new 7690075Sobrien quantity number to describe the value generated by this operation. 7790075Sobrien `reg_qty' records what quantity a register is currently thought 7890075Sobrien of as containing. 7990075Sobrien 8090075Sobrien All real quantity numbers are greater than or equal to `max_reg'. 8190075Sobrien If register N has not been assigned a quantity, reg_qty[N] will equal N. 8290075Sobrien 8390075Sobrien Quantity numbers below `max_reg' do not exist and none of the `qty_table' 8490075Sobrien entries should be referenced with an index below `max_reg'. 8590075Sobrien 8690075Sobrien We also maintain a bidirectional chain of registers for each 8790075Sobrien quantity number. The `qty_table` members `first_reg' and `last_reg', 8890075Sobrien and `reg_eqv_table' members `next' and `prev' hold these chains. 8990075Sobrien 9090075Sobrien The first register in a chain is the one whose lifespan is least local. 9190075Sobrien Among equals, it is the one that was seen first. 9290075Sobrien We replace any equivalent register with that one. 9390075Sobrien 9490075Sobrien If two registers have the same quantity number, it must be true that 9590075Sobrien REG expressions with qty_table `mode' must be in the hash table for both 9690075Sobrien registers and must be in the same class. 9790075Sobrien 9890075Sobrien The converse is not true. Since hard registers may be referenced in 9990075Sobrien any mode, two REG expressions might be equivalent in the hash table 10090075Sobrien but not have the same quantity number if the quantity number of one 10190075Sobrien of the registers is not the same mode as those expressions. 10290075Sobrien 10390075SobrienConstants and quantity numbers 10490075Sobrien 10590075Sobrien When a quantity has a known constant value, that value is stored 10690075Sobrien in the appropriate qty_table `const_rtx'. This is in addition to 10790075Sobrien putting the constant in the hash table as is usual for non-regs. 10890075Sobrien 10990075Sobrien Whether a reg or a constant is preferred is determined by the configuration 11090075Sobrien macro CONST_COSTS and will often depend on the constant value. In any 11190075Sobrien event, expressions containing constants can be simplified, by fold_rtx. 11290075Sobrien 11390075Sobrien When a quantity has a known nearly constant value (such as an address 11490075Sobrien of a stack slot), that value is stored in the appropriate qty_table 11590075Sobrien `const_rtx'. 11690075Sobrien 11790075Sobrien Integer constants don't have a machine mode. However, cse 11890075Sobrien determines the intended machine mode from the destination 11990075Sobrien of the instruction that moves the constant. The machine mode 12090075Sobrien is recorded in the hash table along with the actual RTL 12190075Sobrien constant expression so that different modes are kept separate. 12290075Sobrien 12390075SobrienOther expressions: 12490075Sobrien 12590075Sobrien To record known equivalences among expressions in general 12690075Sobrien we use a hash table called `table'. It has a fixed number of buckets 12790075Sobrien that contain chains of `struct table_elt' elements for expressions. 12890075Sobrien These chains connect the elements whose expressions have the same 12990075Sobrien hash codes. 13090075Sobrien 13190075Sobrien Other chains through the same elements connect the elements which 13290075Sobrien currently have equivalent values. 13390075Sobrien 13490075Sobrien Register references in an expression are canonicalized before hashing 13590075Sobrien the expression. This is done using `reg_qty' and qty_table `first_reg'. 13690075Sobrien The hash code of a register reference is computed using the quantity 13790075Sobrien number, not the register number. 13890075Sobrien 13990075Sobrien When the value of an expression changes, it is necessary to remove from the 14090075Sobrien hash table not just that expression but all expressions whose values 14190075Sobrien could be different as a result. 14290075Sobrien 14390075Sobrien 1. If the value changing is in memory, except in special cases 14490075Sobrien ANYTHING referring to memory could be changed. That is because 14590075Sobrien nobody knows where a pointer does not point. 14690075Sobrien The function `invalidate_memory' removes what is necessary. 14790075Sobrien 14890075Sobrien The special cases are when the address is constant or is 14990075Sobrien a constant plus a fixed register such as the frame pointer 15090075Sobrien or a static chain pointer. When such addresses are stored in, 15190075Sobrien we can tell exactly which other such addresses must be invalidated 15290075Sobrien due to overlap. `invalidate' does this. 15390075Sobrien All expressions that refer to non-constant 15490075Sobrien memory addresses are also invalidated. `invalidate_memory' does this. 15590075Sobrien 15690075Sobrien 2. If the value changing is a register, all expressions 15790075Sobrien containing references to that register, and only those, 15890075Sobrien must be removed. 15990075Sobrien 16090075Sobrien Because searching the entire hash table for expressions that contain 16190075Sobrien a register is very slow, we try to figure out when it isn't necessary. 16290075Sobrien Precisely, this is necessary only when expressions have been 16390075Sobrien entered in the hash table using this register, and then the value has 16490075Sobrien changed, and then another expression wants to be added to refer to 16590075Sobrien the register's new value. This sequence of circumstances is rare 16690075Sobrien within any one basic block. 16790075Sobrien 16890075Sobrien The vectors `reg_tick' and `reg_in_table' are used to detect this case. 16990075Sobrien reg_tick[i] is incremented whenever a value is stored in register i. 17090075Sobrien reg_in_table[i] holds -1 if no references to register i have been 17190075Sobrien entered in the table; otherwise, it contains the value reg_tick[i] had 17290075Sobrien when the references were entered. If we want to enter a reference 17390075Sobrien and reg_in_table[i] != reg_tick[i], we must scan and remove old references. 17490075Sobrien Until we want to enter a new entry, the mere fact that the two vectors 17590075Sobrien don't match makes the entries be ignored if anyone tries to match them. 17690075Sobrien 17790075Sobrien Registers themselves are entered in the hash table as well as in 17890075Sobrien the equivalent-register chains. However, the vectors `reg_tick' 17990075Sobrien and `reg_in_table' do not apply to expressions which are simple 18090075Sobrien register references. These expressions are removed from the table 18190075Sobrien immediately when they become invalid, and this can be done even if 18290075Sobrien we do not immediately search for all the expressions that refer to 18390075Sobrien the register. 18490075Sobrien 18590075Sobrien A CLOBBER rtx in an instruction invalidates its operand for further 18690075Sobrien reuse. A CLOBBER or SET rtx whose operand is a MEM:BLK 18790075Sobrien invalidates everything that resides in memory. 18890075Sobrien 18990075SobrienRelated expressions: 19090075Sobrien 19190075Sobrien Constant expressions that differ only by an additive integer 19290075Sobrien are called related. When a constant expression is put in 19390075Sobrien the table, the related expression with no constant term 19490075Sobrien is also entered. These are made to point at each other 19590075Sobrien so that it is possible to find out if there exists any 19690075Sobrien register equivalent to an expression related to a given expression. */ 19790075Sobrien 19890075Sobrien/* One plus largest register number used in this function. */ 19990075Sobrien 20090075Sobrienstatic int max_reg; 20190075Sobrien 20290075Sobrien/* One plus largest instruction UID used in this function at time of 20390075Sobrien cse_main call. */ 20490075Sobrien 20590075Sobrienstatic int max_insn_uid; 20690075Sobrien 20790075Sobrien/* Length of qty_table vector. We know in advance we will not need 20890075Sobrien a quantity number this big. */ 20990075Sobrien 21090075Sobrienstatic int max_qty; 21190075Sobrien 21290075Sobrien/* Next quantity number to be allocated. 21390075Sobrien This is 1 + the largest number needed so far. */ 21490075Sobrien 21590075Sobrienstatic int next_qty; 21690075Sobrien 21790075Sobrien/* Per-qty information tracking. 21890075Sobrien 21990075Sobrien `first_reg' and `last_reg' track the head and tail of the 22090075Sobrien chain of registers which currently contain this quantity. 22190075Sobrien 22290075Sobrien `mode' contains the machine mode of this quantity. 22390075Sobrien 22490075Sobrien `const_rtx' holds the rtx of the constant value of this 22590075Sobrien quantity, if known. A summations of the frame/arg pointer 22690075Sobrien and a constant can also be entered here. When this holds 22790075Sobrien a known value, `const_insn' is the insn which stored the 22890075Sobrien constant value. 22990075Sobrien 23090075Sobrien `comparison_{code,const,qty}' are used to track when a 23190075Sobrien comparison between a quantity and some constant or register has 23290075Sobrien been passed. In such a case, we know the results of the comparison 23390075Sobrien in case we see it again. These members record a comparison that 23490075Sobrien is known to be true. `comparison_code' holds the rtx code of such 23590075Sobrien a comparison, else it is set to UNKNOWN and the other two 23690075Sobrien comparison members are undefined. `comparison_const' holds 23790075Sobrien the constant being compared against, or zero if the comparison 23890075Sobrien is not against a constant. `comparison_qty' holds the quantity 23990075Sobrien being compared against when the result is known. If the comparison 24090075Sobrien is not with a register, `comparison_qty' is -1. */ 24190075Sobrien 24290075Sobrienstruct qty_table_elem 24390075Sobrien{ 24490075Sobrien rtx const_rtx; 24590075Sobrien rtx const_insn; 24690075Sobrien rtx comparison_const; 24790075Sobrien int comparison_qty; 24890075Sobrien unsigned int first_reg, last_reg; 24990075Sobrien enum machine_mode mode; 25090075Sobrien enum rtx_code comparison_code; 25190075Sobrien}; 25290075Sobrien 25390075Sobrien/* The table of all qtys, indexed by qty number. */ 25490075Sobrienstatic struct qty_table_elem *qty_table; 25590075Sobrien 25690075Sobrien#ifdef HAVE_cc0 25790075Sobrien/* For machines that have a CC0, we do not record its value in the hash 25890075Sobrien table since its use is guaranteed to be the insn immediately following 25990075Sobrien its definition and any other insn is presumed to invalidate it. 26090075Sobrien 26190075Sobrien Instead, we store below the value last assigned to CC0. If it should 26290075Sobrien happen to be a constant, it is stored in preference to the actual 26390075Sobrien assigned value. In case it is a constant, we store the mode in which 26490075Sobrien the constant should be interpreted. */ 26590075Sobrien 26690075Sobrienstatic rtx prev_insn_cc0; 26790075Sobrienstatic enum machine_mode prev_insn_cc0_mode; 26890075Sobrien#endif 26990075Sobrien 27090075Sobrien/* Previous actual insn. 0 if at first insn of basic block. */ 27190075Sobrien 27290075Sobrienstatic rtx prev_insn; 27390075Sobrien 27490075Sobrien/* Insn being scanned. */ 27590075Sobrien 27690075Sobrienstatic rtx this_insn; 27790075Sobrien 27890075Sobrien/* Index by register number, gives the number of the next (or 27990075Sobrien previous) register in the chain of registers sharing the same 28090075Sobrien value. 28190075Sobrien 28290075Sobrien Or -1 if this register is at the end of the chain. 28390075Sobrien 28490075Sobrien If reg_qty[N] == N, reg_eqv_table[N].next is undefined. */ 28590075Sobrien 28690075Sobrien/* Per-register equivalence chain. */ 28790075Sobrienstruct reg_eqv_elem 28890075Sobrien{ 28990075Sobrien int next, prev; 29090075Sobrien}; 29190075Sobrien 29290075Sobrien/* The table of all register equivalence chains. */ 29390075Sobrienstatic struct reg_eqv_elem *reg_eqv_table; 29490075Sobrien 29590075Sobrienstruct cse_reg_info 29690075Sobrien{ 29790075Sobrien /* Next in hash chain. */ 29890075Sobrien struct cse_reg_info *hash_next; 29990075Sobrien 30090075Sobrien /* The next cse_reg_info structure in the free or used list. */ 30190075Sobrien struct cse_reg_info *next; 30290075Sobrien 30390075Sobrien /* Search key */ 30490075Sobrien unsigned int regno; 30590075Sobrien 30690075Sobrien /* The quantity number of the register's current contents. */ 30790075Sobrien int reg_qty; 30890075Sobrien 30990075Sobrien /* The number of times the register has been altered in the current 31090075Sobrien basic block. */ 31190075Sobrien int reg_tick; 31290075Sobrien 31390075Sobrien /* The REG_TICK value at which rtx's containing this register are 31490075Sobrien valid in the hash table. If this does not equal the current 31590075Sobrien reg_tick value, such expressions existing in the hash table are 31690075Sobrien invalid. */ 31790075Sobrien int reg_in_table; 31890075Sobrien}; 31990075Sobrien 32090075Sobrien/* A free list of cse_reg_info entries. */ 32190075Sobrienstatic struct cse_reg_info *cse_reg_info_free_list; 32290075Sobrien 32390075Sobrien/* A used list of cse_reg_info entries. */ 32490075Sobrienstatic struct cse_reg_info *cse_reg_info_used_list; 32590075Sobrienstatic struct cse_reg_info *cse_reg_info_used_list_end; 32690075Sobrien 32790075Sobrien/* A mapping from registers to cse_reg_info data structures. */ 32890075Sobrien#define REGHASH_SHIFT 7 32990075Sobrien#define REGHASH_SIZE (1 << REGHASH_SHIFT) 33090075Sobrien#define REGHASH_MASK (REGHASH_SIZE - 1) 33190075Sobrienstatic struct cse_reg_info *reg_hash[REGHASH_SIZE]; 33290075Sobrien 33390075Sobrien#define REGHASH_FN(REGNO) \ 33490075Sobrien (((REGNO) ^ ((REGNO) >> REGHASH_SHIFT)) & REGHASH_MASK) 33590075Sobrien 33690075Sobrien/* The last lookup we did into the cse_reg_info_tree. This allows us 33790075Sobrien to cache repeated lookups. */ 33890075Sobrienstatic unsigned int cached_regno; 33990075Sobrienstatic struct cse_reg_info *cached_cse_reg_info; 34090075Sobrien 34190075Sobrien/* A HARD_REG_SET containing all the hard registers for which there is 34290075Sobrien currently a REG expression in the hash table. Note the difference 34390075Sobrien from the above variables, which indicate if the REG is mentioned in some 34490075Sobrien expression in the table. */ 34590075Sobrien 34690075Sobrienstatic HARD_REG_SET hard_regs_in_table; 34790075Sobrien 34890075Sobrien/* CUID of insn that starts the basic block currently being cse-processed. */ 34990075Sobrien 35090075Sobrienstatic int cse_basic_block_start; 35190075Sobrien 35290075Sobrien/* CUID of insn that ends the basic block currently being cse-processed. */ 35390075Sobrien 35490075Sobrienstatic int cse_basic_block_end; 35590075Sobrien 35690075Sobrien/* Vector mapping INSN_UIDs to cuids. 35790075Sobrien The cuids are like uids but increase monotonically always. 35890075Sobrien We use them to see whether a reg is used outside a given basic block. */ 35990075Sobrien 36090075Sobrienstatic int *uid_cuid; 36190075Sobrien 36290075Sobrien/* Highest UID in UID_CUID. */ 36390075Sobrienstatic int max_uid; 36490075Sobrien 36590075Sobrien/* Get the cuid of an insn. */ 36690075Sobrien 36790075Sobrien#define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)]) 36890075Sobrien 36990075Sobrien/* Nonzero if this pass has made changes, and therefore it's 37090075Sobrien worthwhile to run the garbage collector. */ 37190075Sobrien 37290075Sobrienstatic int cse_altered; 37390075Sobrien 37490075Sobrien/* Nonzero if cse has altered conditional jump insns 37590075Sobrien in such a way that jump optimization should be redone. */ 37690075Sobrien 37790075Sobrienstatic int cse_jumps_altered; 37890075Sobrien 37990075Sobrien/* Nonzero if we put a LABEL_REF into the hash table for an INSN without a 38090075Sobrien REG_LABEL, we have to rerun jump after CSE to put in the note. */ 38190075Sobrienstatic int recorded_label_ref; 38290075Sobrien 38390075Sobrien/* canon_hash stores 1 in do_not_record 38490075Sobrien if it notices a reference to CC0, PC, or some other volatile 38590075Sobrien subexpression. */ 38690075Sobrien 38790075Sobrienstatic int do_not_record; 38890075Sobrien 38990075Sobrien#ifdef LOAD_EXTEND_OP 39090075Sobrien 39190075Sobrien/* Scratch rtl used when looking for load-extended copy of a MEM. */ 39290075Sobrienstatic rtx memory_extend_rtx; 39390075Sobrien#endif 39490075Sobrien 39590075Sobrien/* canon_hash stores 1 in hash_arg_in_memory 39690075Sobrien if it notices a reference to memory within the expression being hashed. */ 39790075Sobrien 39890075Sobrienstatic int hash_arg_in_memory; 39990075Sobrien 40090075Sobrien/* The hash table contains buckets which are chains of `struct table_elt's, 40190075Sobrien each recording one expression's information. 40290075Sobrien That expression is in the `exp' field. 40390075Sobrien 40490075Sobrien The canon_exp field contains a canonical (from the point of view of 40590075Sobrien alias analysis) version of the `exp' field. 40690075Sobrien 40790075Sobrien Those elements with the same hash code are chained in both directions 40890075Sobrien through the `next_same_hash' and `prev_same_hash' fields. 40990075Sobrien 41090075Sobrien Each set of expressions with equivalent values 41190075Sobrien are on a two-way chain through the `next_same_value' 41290075Sobrien and `prev_same_value' fields, and all point with 41390075Sobrien the `first_same_value' field at the first element in 41490075Sobrien that chain. The chain is in order of increasing cost. 41590075Sobrien Each element's cost value is in its `cost' field. 41690075Sobrien 41790075Sobrien The `in_memory' field is nonzero for elements that 41890075Sobrien involve any reference to memory. These elements are removed 41990075Sobrien whenever a write is done to an unidentified location in memory. 42090075Sobrien To be safe, we assume that a memory address is unidentified unless 42190075Sobrien the address is either a symbol constant or a constant plus 42290075Sobrien the frame pointer or argument pointer. 42390075Sobrien 42490075Sobrien The `related_value' field is used to connect related expressions 42590075Sobrien (that differ by adding an integer). 42690075Sobrien The related expressions are chained in a circular fashion. 42790075Sobrien `related_value' is zero for expressions for which this 42890075Sobrien chain is not useful. 42990075Sobrien 43090075Sobrien The `cost' field stores the cost of this element's expression. 43190075Sobrien The `regcost' field stores the value returned by approx_reg_cost for 43290075Sobrien this element's expression. 43390075Sobrien 43490075Sobrien The `is_const' flag is set if the element is a constant (including 43590075Sobrien a fixed address). 43690075Sobrien 43790075Sobrien The `flag' field is used as a temporary during some search routines. 43890075Sobrien 43990075Sobrien The `mode' field is usually the same as GET_MODE (`exp'), but 44090075Sobrien if `exp' is a CONST_INT and has no machine mode then the `mode' 44190075Sobrien field is the mode it was being used as. Each constant is 44290075Sobrien recorded separately for each mode it is used with. */ 44390075Sobrien 44490075Sobrienstruct table_elt 44590075Sobrien{ 44690075Sobrien rtx exp; 44790075Sobrien rtx canon_exp; 44890075Sobrien struct table_elt *next_same_hash; 44990075Sobrien struct table_elt *prev_same_hash; 45090075Sobrien struct table_elt *next_same_value; 45190075Sobrien struct table_elt *prev_same_value; 45290075Sobrien struct table_elt *first_same_value; 45390075Sobrien struct table_elt *related_value; 45490075Sobrien int cost; 45590075Sobrien int regcost; 45690075Sobrien enum machine_mode mode; 45790075Sobrien char in_memory; 45890075Sobrien char is_const; 45990075Sobrien char flag; 46090075Sobrien}; 46190075Sobrien 46290075Sobrien/* We don't want a lot of buckets, because we rarely have very many 46390075Sobrien things stored in the hash table, and a lot of buckets slows 46490075Sobrien down a lot of loops that happen frequently. */ 46590075Sobrien#define HASH_SHIFT 5 46690075Sobrien#define HASH_SIZE (1 << HASH_SHIFT) 46790075Sobrien#define HASH_MASK (HASH_SIZE - 1) 46890075Sobrien 46990075Sobrien/* Compute hash code of X in mode M. Special-case case where X is a pseudo 47090075Sobrien register (hard registers may require `do_not_record' to be set). */ 47190075Sobrien 47290075Sobrien#define HASH(X, M) \ 47390075Sobrien ((GET_CODE (X) == REG && REGNO (X) >= FIRST_PSEUDO_REGISTER \ 47490075Sobrien ? (((unsigned) REG << 7) + (unsigned) REG_QTY (REGNO (X))) \ 47590075Sobrien : canon_hash (X, M)) & HASH_MASK) 47690075Sobrien 47790075Sobrien/* Determine whether register number N is considered a fixed register for the 47890075Sobrien purpose of approximating register costs. 47990075Sobrien It is desirable to replace other regs with fixed regs, to reduce need for 48090075Sobrien non-fixed hard regs. 48190075Sobrien A reg wins if it is either the frame pointer or designated as fixed. */ 48290075Sobrien#define FIXED_REGNO_P(N) \ 48390075Sobrien ((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \ 48490075Sobrien || fixed_regs[N] || global_regs[N]) 48590075Sobrien 48690075Sobrien/* Compute cost of X, as stored in the `cost' field of a table_elt. Fixed 48790075Sobrien hard registers and pointers into the frame are the cheapest with a cost 48890075Sobrien of 0. Next come pseudos with a cost of one and other hard registers with 48990075Sobrien a cost of 2. Aside from these special cases, call `rtx_cost'. */ 49090075Sobrien 49190075Sobrien#define CHEAP_REGNO(N) \ 49290075Sobrien ((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \ 49390075Sobrien || (N) == STACK_POINTER_REGNUM || (N) == ARG_POINTER_REGNUM \ 49490075Sobrien || ((N) >= FIRST_VIRTUAL_REGISTER && (N) <= LAST_VIRTUAL_REGISTER) \ 49590075Sobrien || ((N) < FIRST_PSEUDO_REGISTER \ 49690075Sobrien && FIXED_REGNO_P (N) && REGNO_REG_CLASS (N) != NO_REGS)) 49790075Sobrien 49890075Sobrien#define COST(X) (GET_CODE (X) == REG ? 0 : notreg_cost (X, SET)) 49990075Sobrien#define COST_IN(X,OUTER) (GET_CODE (X) == REG ? 0 : notreg_cost (X, OUTER)) 50090075Sobrien 50190075Sobrien/* Get the info associated with register N. */ 50290075Sobrien 50390075Sobrien#define GET_CSE_REG_INFO(N) \ 50490075Sobrien (((N) == cached_regno && cached_cse_reg_info) \ 50590075Sobrien ? cached_cse_reg_info : get_cse_reg_info ((N))) 50690075Sobrien 50790075Sobrien/* Get the number of times this register has been updated in this 50890075Sobrien basic block. */ 50990075Sobrien 51090075Sobrien#define REG_TICK(N) ((GET_CSE_REG_INFO (N))->reg_tick) 51190075Sobrien 51290075Sobrien/* Get the point at which REG was recorded in the table. */ 51390075Sobrien 51490075Sobrien#define REG_IN_TABLE(N) ((GET_CSE_REG_INFO (N))->reg_in_table) 51590075Sobrien 51690075Sobrien/* Get the quantity number for REG. */ 51790075Sobrien 51890075Sobrien#define REG_QTY(N) ((GET_CSE_REG_INFO (N))->reg_qty) 51990075Sobrien 52090075Sobrien/* Determine if the quantity number for register X represents a valid index 52190075Sobrien into the qty_table. */ 52290075Sobrien 52390075Sobrien#define REGNO_QTY_VALID_P(N) (REG_QTY (N) != (int) (N)) 52490075Sobrien 52590075Sobrienstatic struct table_elt *table[HASH_SIZE]; 52690075Sobrien 52790075Sobrien/* Chain of `struct table_elt's made so far for this function 52890075Sobrien but currently removed from the table. */ 52990075Sobrien 53090075Sobrienstatic struct table_elt *free_element_chain; 53190075Sobrien 53290075Sobrien/* Number of `struct table_elt' structures made so far for this function. */ 53390075Sobrien 53490075Sobrienstatic int n_elements_made; 53590075Sobrien 53690075Sobrien/* Maximum value `n_elements_made' has had so far in this compilation 53790075Sobrien for functions previously processed. */ 53890075Sobrien 53990075Sobrienstatic int max_elements_made; 54090075Sobrien 54190075Sobrien/* Surviving equivalence class when two equivalence classes are merged 54290075Sobrien by recording the effects of a jump in the last insn. Zero if the 54390075Sobrien last insn was not a conditional jump. */ 54490075Sobrien 54590075Sobrienstatic struct table_elt *last_jump_equiv_class; 54690075Sobrien 54790075Sobrien/* Set to the cost of a constant pool reference if one was found for a 54890075Sobrien symbolic constant. If this was found, it means we should try to 54990075Sobrien convert constants into constant pool entries if they don't fit in 55090075Sobrien the insn. */ 55190075Sobrien 55290075Sobrienstatic int constant_pool_entries_cost; 55390075Sobrien 55490075Sobrien/* Define maximum length of a branch path. */ 55590075Sobrien 55690075Sobrien#define PATHLENGTH 10 55790075Sobrien 55890075Sobrien/* This data describes a block that will be processed by cse_basic_block. */ 55990075Sobrien 56090075Sobrienstruct cse_basic_block_data 56190075Sobrien{ 56290075Sobrien /* Lowest CUID value of insns in block. */ 56390075Sobrien int low_cuid; 56490075Sobrien /* Highest CUID value of insns in block. */ 56590075Sobrien int high_cuid; 56690075Sobrien /* Total number of SETs in block. */ 56790075Sobrien int nsets; 56890075Sobrien /* Last insn in the block. */ 56990075Sobrien rtx last; 57090075Sobrien /* Size of current branch path, if any. */ 57190075Sobrien int path_size; 57290075Sobrien /* Current branch path, indicating which branches will be taken. */ 57390075Sobrien struct branch_path 57490075Sobrien { 57590075Sobrien /* The branch insn. */ 57690075Sobrien rtx branch; 57790075Sobrien /* Whether it should be taken or not. AROUND is the same as taken 57890075Sobrien except that it is used when the destination label is not preceded 57990075Sobrien by a BARRIER. */ 58090075Sobrien enum taken {TAKEN, NOT_TAKEN, AROUND} status; 58190075Sobrien } path[PATHLENGTH]; 58290075Sobrien}; 58390075Sobrien 58490075Sobrien/* Nonzero if X has the form (PLUS frame-pointer integer). We check for 58590075Sobrien virtual regs here because the simplify_*_operation routines are called 58690075Sobrien by integrate.c, which is called before virtual register instantiation. 58790075Sobrien 58890075Sobrien ?!? FIXED_BASE_PLUS_P and NONZERO_BASE_PLUS_P need to move into 58990075Sobrien a header file so that their definitions can be shared with the 59090075Sobrien simplification routines in simplify-rtx.c. Until then, do not 59190075Sobrien change these macros without also changing the copy in simplify-rtx.c. */ 59290075Sobrien 59390075Sobrien#define FIXED_BASE_PLUS_P(X) \ 59490075Sobrien ((X) == frame_pointer_rtx || (X) == hard_frame_pointer_rtx \ 59590075Sobrien || ((X) == arg_pointer_rtx && fixed_regs[ARG_POINTER_REGNUM])\ 59690075Sobrien || (X) == virtual_stack_vars_rtx \ 59790075Sobrien || (X) == virtual_incoming_args_rtx \ 59890075Sobrien || (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \ 59990075Sobrien && (XEXP (X, 0) == frame_pointer_rtx \ 60090075Sobrien || XEXP (X, 0) == hard_frame_pointer_rtx \ 60190075Sobrien || ((X) == arg_pointer_rtx \ 60290075Sobrien && fixed_regs[ARG_POINTER_REGNUM]) \ 60390075Sobrien || XEXP (X, 0) == virtual_stack_vars_rtx \ 60490075Sobrien || XEXP (X, 0) == virtual_incoming_args_rtx)) \ 60590075Sobrien || GET_CODE (X) == ADDRESSOF) 60690075Sobrien 60790075Sobrien/* Similar, but also allows reference to the stack pointer. 60890075Sobrien 60990075Sobrien This used to include FIXED_BASE_PLUS_P, however, we can't assume that 61090075Sobrien arg_pointer_rtx by itself is nonzero, because on at least one machine, 61190075Sobrien the i960, the arg pointer is zero when it is unused. */ 61290075Sobrien 61390075Sobrien#define NONZERO_BASE_PLUS_P(X) \ 61490075Sobrien ((X) == frame_pointer_rtx || (X) == hard_frame_pointer_rtx \ 61590075Sobrien || (X) == virtual_stack_vars_rtx \ 61690075Sobrien || (X) == virtual_incoming_args_rtx \ 61790075Sobrien || (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \ 61890075Sobrien && (XEXP (X, 0) == frame_pointer_rtx \ 61990075Sobrien || XEXP (X, 0) == hard_frame_pointer_rtx \ 62090075Sobrien || ((X) == arg_pointer_rtx \ 62190075Sobrien && fixed_regs[ARG_POINTER_REGNUM]) \ 62290075Sobrien || XEXP (X, 0) == virtual_stack_vars_rtx \ 62390075Sobrien || XEXP (X, 0) == virtual_incoming_args_rtx)) \ 62490075Sobrien || (X) == stack_pointer_rtx \ 62590075Sobrien || (X) == virtual_stack_dynamic_rtx \ 62690075Sobrien || (X) == virtual_outgoing_args_rtx \ 62790075Sobrien || (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \ 62890075Sobrien && (XEXP (X, 0) == stack_pointer_rtx \ 62990075Sobrien || XEXP (X, 0) == virtual_stack_dynamic_rtx \ 63090075Sobrien || XEXP (X, 0) == virtual_outgoing_args_rtx)) \ 63190075Sobrien || GET_CODE (X) == ADDRESSOF) 63290075Sobrien 63390075Sobrienstatic int notreg_cost PARAMS ((rtx, enum rtx_code)); 63490075Sobrienstatic int approx_reg_cost_1 PARAMS ((rtx *, void *)); 63590075Sobrienstatic int approx_reg_cost PARAMS ((rtx)); 63690075Sobrienstatic int preferrable PARAMS ((int, int, int, int)); 63790075Sobrienstatic void new_basic_block PARAMS ((void)); 63890075Sobrienstatic void make_new_qty PARAMS ((unsigned int, enum machine_mode)); 63990075Sobrienstatic void make_regs_eqv PARAMS ((unsigned int, unsigned int)); 64090075Sobrienstatic void delete_reg_equiv PARAMS ((unsigned int)); 64190075Sobrienstatic int mention_regs PARAMS ((rtx)); 64290075Sobrienstatic int insert_regs PARAMS ((rtx, struct table_elt *, int)); 64390075Sobrienstatic void remove_from_table PARAMS ((struct table_elt *, unsigned)); 64490075Sobrienstatic struct table_elt *lookup PARAMS ((rtx, unsigned, enum machine_mode)), 64590075Sobrien *lookup_for_remove PARAMS ((rtx, unsigned, enum machine_mode)); 64690075Sobrienstatic rtx lookup_as_function PARAMS ((rtx, enum rtx_code)); 64790075Sobrienstatic struct table_elt *insert PARAMS ((rtx, struct table_elt *, unsigned, 64890075Sobrien enum machine_mode)); 64990075Sobrienstatic void merge_equiv_classes PARAMS ((struct table_elt *, 65090075Sobrien struct table_elt *)); 65190075Sobrienstatic void invalidate PARAMS ((rtx, enum machine_mode)); 65290075Sobrienstatic int cse_rtx_varies_p PARAMS ((rtx, int)); 65390075Sobrienstatic void remove_invalid_refs PARAMS ((unsigned int)); 65490075Sobrienstatic void remove_invalid_subreg_refs PARAMS ((unsigned int, unsigned int, 65590075Sobrien enum machine_mode)); 65690075Sobrienstatic void rehash_using_reg PARAMS ((rtx)); 65790075Sobrienstatic void invalidate_memory PARAMS ((void)); 65890075Sobrienstatic void invalidate_for_call PARAMS ((void)); 65990075Sobrienstatic rtx use_related_value PARAMS ((rtx, struct table_elt *)); 66090075Sobrienstatic unsigned canon_hash PARAMS ((rtx, enum machine_mode)); 66190075Sobrienstatic unsigned canon_hash_string PARAMS ((const char *)); 66290075Sobrienstatic unsigned safe_hash PARAMS ((rtx, enum machine_mode)); 66390075Sobrienstatic int exp_equiv_p PARAMS ((rtx, rtx, int, int)); 66490075Sobrienstatic rtx canon_reg PARAMS ((rtx, rtx)); 66590075Sobrienstatic void find_best_addr PARAMS ((rtx, rtx *, enum machine_mode)); 66690075Sobrienstatic enum rtx_code find_comparison_args PARAMS ((enum rtx_code, rtx *, rtx *, 66790075Sobrien enum machine_mode *, 66890075Sobrien enum machine_mode *)); 66990075Sobrienstatic rtx fold_rtx PARAMS ((rtx, rtx)); 67090075Sobrienstatic rtx equiv_constant PARAMS ((rtx)); 67190075Sobrienstatic void record_jump_equiv PARAMS ((rtx, int)); 67290075Sobrienstatic void record_jump_cond PARAMS ((enum rtx_code, enum machine_mode, 67390075Sobrien rtx, rtx, int)); 67490075Sobrienstatic void cse_insn PARAMS ((rtx, rtx)); 67590075Sobrienstatic int addr_affects_sp_p PARAMS ((rtx)); 67690075Sobrienstatic void invalidate_from_clobbers PARAMS ((rtx)); 67790075Sobrienstatic rtx cse_process_notes PARAMS ((rtx, rtx)); 67890075Sobrienstatic void cse_around_loop PARAMS ((rtx)); 67990075Sobrienstatic void invalidate_skipped_set PARAMS ((rtx, rtx, void *)); 68090075Sobrienstatic void invalidate_skipped_block PARAMS ((rtx)); 68190075Sobrienstatic void cse_check_loop_start PARAMS ((rtx, rtx, void *)); 68290075Sobrienstatic void cse_set_around_loop PARAMS ((rtx, rtx, rtx)); 68390075Sobrienstatic rtx cse_basic_block PARAMS ((rtx, rtx, struct branch_path *, int)); 68490075Sobrienstatic void count_reg_usage PARAMS ((rtx, int *, rtx, int)); 68590075Sobrienstatic int check_for_label_ref PARAMS ((rtx *, void *)); 68690075Sobrienextern void dump_class PARAMS ((struct table_elt*)); 68790075Sobrienstatic struct cse_reg_info * get_cse_reg_info PARAMS ((unsigned int)); 68890075Sobrienstatic int check_dependence PARAMS ((rtx *, void *)); 68990075Sobrien 69090075Sobrienstatic void flush_hash_table PARAMS ((void)); 69190075Sobrienstatic bool insn_live_p PARAMS ((rtx, int *)); 69290075Sobrienstatic bool set_live_p PARAMS ((rtx, rtx, int *)); 69390075Sobrienstatic bool dead_libcall_p PARAMS ((rtx)); 69490075Sobrien 69590075Sobrien/* Dump the expressions in the equivalence class indicated by CLASSP. 69690075Sobrien This function is used only for debugging. */ 69790075Sobrienvoid 69890075Sobriendump_class (classp) 69990075Sobrien struct table_elt *classp; 70090075Sobrien{ 70190075Sobrien struct table_elt *elt; 70290075Sobrien 70390075Sobrien fprintf (stderr, "Equivalence chain for "); 70490075Sobrien print_rtl (stderr, classp->exp); 70590075Sobrien fprintf (stderr, ": \n"); 70690075Sobrien 70790075Sobrien for (elt = classp->first_same_value; elt; elt = elt->next_same_value) 70890075Sobrien { 70990075Sobrien print_rtl (stderr, elt->exp); 71090075Sobrien fprintf (stderr, "\n"); 71190075Sobrien } 71290075Sobrien} 71390075Sobrien 71490075Sobrien/* Subroutine of approx_reg_cost; called through for_each_rtx. */ 71590075Sobrien 71690075Sobrienstatic int 71790075Sobrienapprox_reg_cost_1 (xp, data) 71890075Sobrien rtx *xp; 71990075Sobrien void *data; 72090075Sobrien{ 72190075Sobrien rtx x = *xp; 72290075Sobrien regset set = (regset) data; 72390075Sobrien 72490075Sobrien if (x && GET_CODE (x) == REG) 72590075Sobrien SET_REGNO_REG_SET (set, REGNO (x)); 72690075Sobrien return 0; 72790075Sobrien} 72890075Sobrien 72990075Sobrien/* Return an estimate of the cost of the registers used in an rtx. 73090075Sobrien This is mostly the number of different REG expressions in the rtx; 73190075Sobrien however for some exceptions like fixed registers we use a cost of 73290075Sobrien 0. If any other hard register reference occurs, return MAX_COST. */ 73390075Sobrien 73490075Sobrienstatic int 73590075Sobrienapprox_reg_cost (x) 73690075Sobrien rtx x; 73790075Sobrien{ 73890075Sobrien regset_head set; 73990075Sobrien int i; 74090075Sobrien int cost = 0; 74190075Sobrien int hardregs = 0; 74290075Sobrien 74390075Sobrien INIT_REG_SET (&set); 74490075Sobrien for_each_rtx (&x, approx_reg_cost_1, (void *)&set); 74590075Sobrien 74690075Sobrien EXECUTE_IF_SET_IN_REG_SET 74790075Sobrien (&set, 0, i, 74890075Sobrien { 74990075Sobrien if (! CHEAP_REGNO (i)) 75090075Sobrien { 75190075Sobrien if (i < FIRST_PSEUDO_REGISTER) 752 hardregs++; 753 754 cost += i < FIRST_PSEUDO_REGISTER ? 2 : 1; 755 } 756 }); 757 758 CLEAR_REG_SET (&set); 759 return hardregs && SMALL_REGISTER_CLASSES ? MAX_COST : cost; 760} 761 762/* Return a negative value if an rtx A, whose costs are given by COST_A 763 and REGCOST_A, is more desirable than an rtx B. 764 Return a positive value if A is less desirable, or 0 if the two are 765 equally good. */ 766static int 767preferrable (cost_a, regcost_a, cost_b, regcost_b) 768 int cost_a, regcost_a, cost_b, regcost_b; 769{ 770 /* First, get rid of a cases involving expressions that are entirely 771 unwanted. */ 772 if (cost_a != cost_b) 773 { 774 if (cost_a == MAX_COST) 775 return 1; 776 if (cost_b == MAX_COST) 777 return -1; 778 } 779 780 /* Avoid extending lifetimes of hardregs. */ 781 if (regcost_a != regcost_b) 782 { 783 if (regcost_a == MAX_COST) 784 return 1; 785 if (regcost_b == MAX_COST) 786 return -1; 787 } 788 789 /* Normal operation costs take precedence. */ 790 if (cost_a != cost_b) 791 return cost_a - cost_b; 792 /* Only if these are identical consider effects on register pressure. */ 793 if (regcost_a != regcost_b) 794 return regcost_a - regcost_b; 795 return 0; 796} 797 798/* Internal function, to compute cost when X is not a register; called 799 from COST macro to keep it simple. */ 800 801static int 802notreg_cost (x, outer) 803 rtx x; 804 enum rtx_code outer; 805{ 806 return ((GET_CODE (x) == SUBREG 807 && GET_CODE (SUBREG_REG (x)) == REG 808 && GET_MODE_CLASS (GET_MODE (x)) == MODE_INT 809 && GET_MODE_CLASS (GET_MODE (SUBREG_REG (x))) == MODE_INT 810 && (GET_MODE_SIZE (GET_MODE (x)) 811 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) 812 && subreg_lowpart_p (x) 813 && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (GET_MODE (x)), 814 GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))))) 815 ? 0 816 : rtx_cost (x, outer) * 2); 817} 818 819/* Return an estimate of the cost of computing rtx X. 820 One use is in cse, to decide which expression to keep in the hash table. 821 Another is in rtl generation, to pick the cheapest way to multiply. 822 Other uses like the latter are expected in the future. */ 823 824int 825rtx_cost (x, outer_code) 826 rtx x; 827 enum rtx_code outer_code ATTRIBUTE_UNUSED; 828{ 829 int i, j; 830 enum rtx_code code; 831 const char *fmt; 832 int total; 833 834 if (x == 0) 835 return 0; 836 837 /* Compute the default costs of certain things. 838 Note that RTX_COSTS can override the defaults. */ 839 840 code = GET_CODE (x); 841 switch (code) 842 { 843 case MULT: 844 /* Count multiplication by 2**n as a shift, 845 because if we are considering it, we would output it as a shift. */ 846 if (GET_CODE (XEXP (x, 1)) == CONST_INT 847 && exact_log2 (INTVAL (XEXP (x, 1))) >= 0) 848 total = 2; 849 else 850 total = COSTS_N_INSNS (5); 851 break; 852 case DIV: 853 case UDIV: 854 case MOD: 855 case UMOD: 856 total = COSTS_N_INSNS (7); 857 break; 858 case USE: 859 /* Used in loop.c and combine.c as a marker. */ 860 total = 0; 861 break; 862 default: 863 total = COSTS_N_INSNS (1); 864 } 865 866 switch (code) 867 { 868 case REG: 869 return 0; 870 871 case SUBREG: 872 /* If we can't tie these modes, make this expensive. The larger 873 the mode, the more expensive it is. */ 874 if (! MODES_TIEABLE_P (GET_MODE (x), GET_MODE (SUBREG_REG (x)))) 875 return COSTS_N_INSNS (2 876 + GET_MODE_SIZE (GET_MODE (x)) / UNITS_PER_WORD); 877 break; 878 879#ifdef RTX_COSTS 880 RTX_COSTS (x, code, outer_code); 881#endif 882#ifdef CONST_COSTS 883 CONST_COSTS (x, code, outer_code); 884#endif 885 886 default: 887#ifdef DEFAULT_RTX_COSTS 888 DEFAULT_RTX_COSTS (x, code, outer_code); 889#endif 890 break; 891 } 892 893 /* Sum the costs of the sub-rtx's, plus cost of this operation, 894 which is already in total. */ 895 896 fmt = GET_RTX_FORMAT (code); 897 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 898 if (fmt[i] == 'e') 899 total += rtx_cost (XEXP (x, i), code); 900 else if (fmt[i] == 'E') 901 for (j = 0; j < XVECLEN (x, i); j++) 902 total += rtx_cost (XVECEXP (x, i, j), code); 903 904 return total; 905} 906 907/* Return cost of address expression X. 908 Expect that X is properly formed address reference. */ 909 910int 911address_cost (x, mode) 912 rtx x; 913 enum machine_mode mode; 914{ 915 /* The ADDRESS_COST macro does not deal with ADDRESSOF nodes. But, 916 during CSE, such nodes are present. Using an ADDRESSOF node which 917 refers to the address of a REG is a good thing because we can then 918 turn (MEM (ADDRESSSOF (REG))) into just plain REG. */ 919 920 if (GET_CODE (x) == ADDRESSOF && REG_P (XEXP ((x), 0))) 921 return -1; 922 923 /* We may be asked for cost of various unusual addresses, such as operands 924 of push instruction. It is not worthwhile to complicate writing 925 of ADDRESS_COST macro by such cases. */ 926 927 if (!memory_address_p (mode, x)) 928 return 1000; 929#ifdef ADDRESS_COST 930 return ADDRESS_COST (x); 931#else 932 return rtx_cost (x, MEM); 933#endif 934} 935 936 937static struct cse_reg_info * 938get_cse_reg_info (regno) 939 unsigned int regno; 940{ 941 struct cse_reg_info **hash_head = ®_hash[REGHASH_FN (regno)]; 942 struct cse_reg_info *p; 943 944 for (p = *hash_head; p != NULL; p = p->hash_next) 945 if (p->regno == regno) 946 break; 947 948 if (p == NULL) 949 { 950 /* Get a new cse_reg_info structure. */ 951 if (cse_reg_info_free_list) 952 { 953 p = cse_reg_info_free_list; 954 cse_reg_info_free_list = p->next; 955 } 956 else 957 p = (struct cse_reg_info *) xmalloc (sizeof (struct cse_reg_info)); 958 959 /* Insert into hash table. */ 960 p->hash_next = *hash_head; 961 *hash_head = p; 962 963 /* Initialize it. */ 964 p->reg_tick = 1; 965 p->reg_in_table = -1; 966 p->reg_qty = regno; 967 p->regno = regno; 968 p->next = cse_reg_info_used_list; 969 cse_reg_info_used_list = p; 970 if (!cse_reg_info_used_list_end) 971 cse_reg_info_used_list_end = p; 972 } 973 974 /* Cache this lookup; we tend to be looking up information about the 975 same register several times in a row. */ 976 cached_regno = regno; 977 cached_cse_reg_info = p; 978 979 return p; 980} 981 982/* Clear the hash table and initialize each register with its own quantity, 983 for a new basic block. */ 984 985static void 986new_basic_block () 987{ 988 int i; 989 990 next_qty = max_reg; 991 992 /* Clear out hash table state for this pass. */ 993 994 memset ((char *) reg_hash, 0, sizeof reg_hash); 995 996 if (cse_reg_info_used_list) 997 { 998 cse_reg_info_used_list_end->next = cse_reg_info_free_list; 999 cse_reg_info_free_list = cse_reg_info_used_list; 1000 cse_reg_info_used_list = cse_reg_info_used_list_end = 0; 1001 } 1002 cached_cse_reg_info = 0; 1003 1004 CLEAR_HARD_REG_SET (hard_regs_in_table); 1005 1006 /* The per-quantity values used to be initialized here, but it is 1007 much faster to initialize each as it is made in `make_new_qty'. */ 1008 1009 for (i = 0; i < HASH_SIZE; i++) 1010 { 1011 struct table_elt *first; 1012 1013 first = table[i]; 1014 if (first != NULL) 1015 { 1016 struct table_elt *last = first; 1017 1018 table[i] = NULL; 1019 1020 while (last->next_same_hash != NULL) 1021 last = last->next_same_hash; 1022 1023 /* Now relink this hash entire chain into 1024 the free element list. */ 1025 1026 last->next_same_hash = free_element_chain; 1027 free_element_chain = first; 1028 } 1029 } 1030 1031 prev_insn = 0; 1032 1033#ifdef HAVE_cc0 1034 prev_insn_cc0 = 0; 1035#endif 1036} 1037 1038/* Say that register REG contains a quantity in mode MODE not in any 1039 register before and initialize that quantity. */ 1040 1041static void 1042make_new_qty (reg, mode) 1043 unsigned int reg; 1044 enum machine_mode mode; 1045{ 1046 int q; 1047 struct qty_table_elem *ent; 1048 struct reg_eqv_elem *eqv; 1049 1050 if (next_qty >= max_qty) 1051 abort (); 1052 1053 q = REG_QTY (reg) = next_qty++; 1054 ent = &qty_table[q]; 1055 ent->first_reg = reg; 1056 ent->last_reg = reg; 1057 ent->mode = mode; 1058 ent->const_rtx = ent->const_insn = NULL_RTX; 1059 ent->comparison_code = UNKNOWN; 1060 1061 eqv = ®_eqv_table[reg]; 1062 eqv->next = eqv->prev = -1; 1063} 1064 1065/* Make reg NEW equivalent to reg OLD. 1066 OLD is not changing; NEW is. */ 1067 1068static void 1069make_regs_eqv (new, old) 1070 unsigned int new, old; 1071{ 1072 unsigned int lastr, firstr; 1073 int q = REG_QTY (old); 1074 struct qty_table_elem *ent; 1075 1076 ent = &qty_table[q]; 1077 1078 /* Nothing should become eqv until it has a "non-invalid" qty number. */ 1079 if (! REGNO_QTY_VALID_P (old)) 1080 abort (); 1081 1082 REG_QTY (new) = q; 1083 firstr = ent->first_reg; 1084 lastr = ent->last_reg; 1085 1086 /* Prefer fixed hard registers to anything. Prefer pseudo regs to other 1087 hard regs. Among pseudos, if NEW will live longer than any other reg 1088 of the same qty, and that is beyond the current basic block, 1089 make it the new canonical replacement for this qty. */ 1090 if (! (firstr < FIRST_PSEUDO_REGISTER && FIXED_REGNO_P (firstr)) 1091 /* Certain fixed registers might be of the class NO_REGS. This means 1092 that not only can they not be allocated by the compiler, but 1093 they cannot be used in substitutions or canonicalizations 1094 either. */ 1095 && (new >= FIRST_PSEUDO_REGISTER || REGNO_REG_CLASS (new) != NO_REGS) 1096 && ((new < FIRST_PSEUDO_REGISTER && FIXED_REGNO_P (new)) 1097 || (new >= FIRST_PSEUDO_REGISTER 1098 && (firstr < FIRST_PSEUDO_REGISTER 1099 || ((uid_cuid[REGNO_LAST_UID (new)] > cse_basic_block_end 1100 || (uid_cuid[REGNO_FIRST_UID (new)] 1101 < cse_basic_block_start)) 1102 && (uid_cuid[REGNO_LAST_UID (new)] 1103 > uid_cuid[REGNO_LAST_UID (firstr)])))))) 1104 { 1105 reg_eqv_table[firstr].prev = new; 1106 reg_eqv_table[new].next = firstr; 1107 reg_eqv_table[new].prev = -1; 1108 ent->first_reg = new; 1109 } 1110 else 1111 { 1112 /* If NEW is a hard reg (known to be non-fixed), insert at end. 1113 Otherwise, insert before any non-fixed hard regs that are at the 1114 end. Registers of class NO_REGS cannot be used as an 1115 equivalent for anything. */ 1116 while (lastr < FIRST_PSEUDO_REGISTER && reg_eqv_table[lastr].prev >= 0 1117 && (REGNO_REG_CLASS (lastr) == NO_REGS || ! FIXED_REGNO_P (lastr)) 1118 && new >= FIRST_PSEUDO_REGISTER) 1119 lastr = reg_eqv_table[lastr].prev; 1120 reg_eqv_table[new].next = reg_eqv_table[lastr].next; 1121 if (reg_eqv_table[lastr].next >= 0) 1122 reg_eqv_table[reg_eqv_table[lastr].next].prev = new; 1123 else 1124 qty_table[q].last_reg = new; 1125 reg_eqv_table[lastr].next = new; 1126 reg_eqv_table[new].prev = lastr; 1127 } 1128} 1129 1130/* Remove REG from its equivalence class. */ 1131 1132static void 1133delete_reg_equiv (reg) 1134 unsigned int reg; 1135{ 1136 struct qty_table_elem *ent; 1137 int q = REG_QTY (reg); 1138 int p, n; 1139 1140 /* If invalid, do nothing. */ 1141 if (q == (int) reg) 1142 return; 1143 1144 ent = &qty_table[q]; 1145 1146 p = reg_eqv_table[reg].prev; 1147 n = reg_eqv_table[reg].next; 1148 1149 if (n != -1) 1150 reg_eqv_table[n].prev = p; 1151 else 1152 ent->last_reg = p; 1153 if (p != -1) 1154 reg_eqv_table[p].next = n; 1155 else 1156 ent->first_reg = n; 1157 1158 REG_QTY (reg) = reg; 1159} 1160 1161/* Remove any invalid expressions from the hash table 1162 that refer to any of the registers contained in expression X. 1163 1164 Make sure that newly inserted references to those registers 1165 as subexpressions will be considered valid. 1166 1167 mention_regs is not called when a register itself 1168 is being stored in the table. 1169 1170 Return 1 if we have done something that may have changed the hash code 1171 of X. */ 1172 1173static int 1174mention_regs (x) 1175 rtx x; 1176{ 1177 enum rtx_code code; 1178 int i, j; 1179 const char *fmt; 1180 int changed = 0; 1181 1182 if (x == 0) 1183 return 0; 1184 1185 code = GET_CODE (x); 1186 if (code == REG) 1187 { 1188 unsigned int regno = REGNO (x); 1189 unsigned int endregno 1190 = regno + (regno >= FIRST_PSEUDO_REGISTER ? 1 1191 : HARD_REGNO_NREGS (regno, GET_MODE (x))); 1192 unsigned int i; 1193 1194 for (i = regno; i < endregno; i++) 1195 { 1196 if (REG_IN_TABLE (i) >= 0 && REG_IN_TABLE (i) != REG_TICK (i)) 1197 remove_invalid_refs (i); 1198 1199 REG_IN_TABLE (i) = REG_TICK (i); 1200 } 1201 1202 return 0; 1203 } 1204 1205 /* If this is a SUBREG, we don't want to discard other SUBREGs of the same 1206 pseudo if they don't use overlapping words. We handle only pseudos 1207 here for simplicity. */ 1208 if (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG 1209 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER) 1210 { 1211 unsigned int i = REGNO (SUBREG_REG (x)); 1212 1213 if (REG_IN_TABLE (i) >= 0 && REG_IN_TABLE (i) != REG_TICK (i)) 1214 { 1215 /* If reg_tick has been incremented more than once since 1216 reg_in_table was last set, that means that the entire 1217 register has been set before, so discard anything memorized 1218 for the entire register, including all SUBREG expressions. */ 1219 if (REG_IN_TABLE (i) != REG_TICK (i) - 1) 1220 remove_invalid_refs (i); 1221 else 1222 remove_invalid_subreg_refs (i, SUBREG_BYTE (x), GET_MODE (x)); 1223 } 1224 1225 REG_IN_TABLE (i) = REG_TICK (i); 1226 return 0; 1227 } 1228 1229 /* If X is a comparison or a COMPARE and either operand is a register 1230 that does not have a quantity, give it one. This is so that a later 1231 call to record_jump_equiv won't cause X to be assigned a different 1232 hash code and not found in the table after that call. 1233 1234 It is not necessary to do this here, since rehash_using_reg can 1235 fix up the table later, but doing this here eliminates the need to 1236 call that expensive function in the most common case where the only 1237 use of the register is in the comparison. */ 1238 1239 if (code == COMPARE || GET_RTX_CLASS (code) == '<') 1240 { 1241 if (GET_CODE (XEXP (x, 0)) == REG 1242 && ! REGNO_QTY_VALID_P (REGNO (XEXP (x, 0)))) 1243 if (insert_regs (XEXP (x, 0), NULL, 0)) 1244 { 1245 rehash_using_reg (XEXP (x, 0)); 1246 changed = 1; 1247 } 1248 1249 if (GET_CODE (XEXP (x, 1)) == REG 1250 && ! REGNO_QTY_VALID_P (REGNO (XEXP (x, 1)))) 1251 if (insert_regs (XEXP (x, 1), NULL, 0)) 1252 { 1253 rehash_using_reg (XEXP (x, 1)); 1254 changed = 1; 1255 } 1256 } 1257 1258 fmt = GET_RTX_FORMAT (code); 1259 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 1260 if (fmt[i] == 'e') 1261 changed |= mention_regs (XEXP (x, i)); 1262 else if (fmt[i] == 'E') 1263 for (j = 0; j < XVECLEN (x, i); j++) 1264 changed |= mention_regs (XVECEXP (x, i, j)); 1265 1266 return changed; 1267} 1268 1269/* Update the register quantities for inserting X into the hash table 1270 with a value equivalent to CLASSP. 1271 (If the class does not contain a REG, it is irrelevant.) 1272 If MODIFIED is nonzero, X is a destination; it is being modified. 1273 Note that delete_reg_equiv should be called on a register 1274 before insert_regs is done on that register with MODIFIED != 0. 1275 1276 Nonzero value means that elements of reg_qty have changed 1277 so X's hash code may be different. */ 1278 1279static int 1280insert_regs (x, classp, modified) 1281 rtx x; 1282 struct table_elt *classp; 1283 int modified; 1284{ 1285 if (GET_CODE (x) == REG) 1286 { 1287 unsigned int regno = REGNO (x); 1288 int qty_valid; 1289 1290 /* If REGNO is in the equivalence table already but is of the 1291 wrong mode for that equivalence, don't do anything here. */ 1292 1293 qty_valid = REGNO_QTY_VALID_P (regno); 1294 if (qty_valid) 1295 { 1296 struct qty_table_elem *ent = &qty_table[REG_QTY (regno)]; 1297 1298 if (ent->mode != GET_MODE (x)) 1299 return 0; 1300 } 1301 1302 if (modified || ! qty_valid) 1303 { 1304 if (classp) 1305 for (classp = classp->first_same_value; 1306 classp != 0; 1307 classp = classp->next_same_value) 1308 if (GET_CODE (classp->exp) == REG 1309 && GET_MODE (classp->exp) == GET_MODE (x)) 1310 { 1311 make_regs_eqv (regno, REGNO (classp->exp)); 1312 return 1; 1313 } 1314 1315 /* Mention_regs for a SUBREG checks if REG_TICK is exactly one larger 1316 than REG_IN_TABLE to find out if there was only a single preceding 1317 invalidation - for the SUBREG - or another one, which would be 1318 for the full register. However, if we find here that REG_TICK 1319 indicates that the register is invalid, it means that it has 1320 been invalidated in a separate operation. The SUBREG might be used 1321 now (then this is a recursive call), or we might use the full REG 1322 now and a SUBREG of it later. So bump up REG_TICK so that 1323 mention_regs will do the right thing. */ 1324 if (! modified 1325 && REG_IN_TABLE (regno) >= 0 1326 && REG_TICK (regno) == REG_IN_TABLE (regno) + 1) 1327 REG_TICK (regno)++; 1328 make_new_qty (regno, GET_MODE (x)); 1329 return 1; 1330 } 1331 1332 return 0; 1333 } 1334 1335 /* If X is a SUBREG, we will likely be inserting the inner register in the 1336 table. If that register doesn't have an assigned quantity number at 1337 this point but does later, the insertion that we will be doing now will 1338 not be accessible because its hash code will have changed. So assign 1339 a quantity number now. */ 1340 1341 else if (GET_CODE (x) == SUBREG && GET_CODE (SUBREG_REG (x)) == REG 1342 && ! REGNO_QTY_VALID_P (REGNO (SUBREG_REG (x)))) 1343 { 1344 insert_regs (SUBREG_REG (x), NULL, 0); 1345 mention_regs (x); 1346 return 1; 1347 } 1348 else 1349 return mention_regs (x); 1350} 1351 1352/* Look in or update the hash table. */ 1353 1354/* Remove table element ELT from use in the table. 1355 HASH is its hash code, made using the HASH macro. 1356 It's an argument because often that is known in advance 1357 and we save much time not recomputing it. */ 1358 1359static void 1360remove_from_table (elt, hash) 1361 struct table_elt *elt; 1362 unsigned hash; 1363{ 1364 if (elt == 0) 1365 return; 1366 1367 /* Mark this element as removed. See cse_insn. */ 1368 elt->first_same_value = 0; 1369 1370 /* Remove the table element from its equivalence class. */ 1371 1372 { 1373 struct table_elt *prev = elt->prev_same_value; 1374 struct table_elt *next = elt->next_same_value; 1375 1376 if (next) 1377 next->prev_same_value = prev; 1378 1379 if (prev) 1380 prev->next_same_value = next; 1381 else 1382 { 1383 struct table_elt *newfirst = next; 1384 while (next) 1385 { 1386 next->first_same_value = newfirst; 1387 next = next->next_same_value; 1388 } 1389 } 1390 } 1391 1392 /* Remove the table element from its hash bucket. */ 1393 1394 { 1395 struct table_elt *prev = elt->prev_same_hash; 1396 struct table_elt *next = elt->next_same_hash; 1397 1398 if (next) 1399 next->prev_same_hash = prev; 1400 1401 if (prev) 1402 prev->next_same_hash = next; 1403 else if (table[hash] == elt) 1404 table[hash] = next; 1405 else 1406 { 1407 /* This entry is not in the proper hash bucket. This can happen 1408 when two classes were merged by `merge_equiv_classes'. Search 1409 for the hash bucket that it heads. This happens only very 1410 rarely, so the cost is acceptable. */ 1411 for (hash = 0; hash < HASH_SIZE; hash++) 1412 if (table[hash] == elt) 1413 table[hash] = next; 1414 } 1415 } 1416 1417 /* Remove the table element from its related-value circular chain. */ 1418 1419 if (elt->related_value != 0 && elt->related_value != elt) 1420 { 1421 struct table_elt *p = elt->related_value; 1422 1423 while (p->related_value != elt) 1424 p = p->related_value; 1425 p->related_value = elt->related_value; 1426 if (p->related_value == p) 1427 p->related_value = 0; 1428 } 1429 1430 /* Now add it to the free element chain. */ 1431 elt->next_same_hash = free_element_chain; 1432 free_element_chain = elt; 1433} 1434 1435/* Look up X in the hash table and return its table element, 1436 or 0 if X is not in the table. 1437 1438 MODE is the machine-mode of X, or if X is an integer constant 1439 with VOIDmode then MODE is the mode with which X will be used. 1440 1441 Here we are satisfied to find an expression whose tree structure 1442 looks like X. */ 1443 1444static struct table_elt * 1445lookup (x, hash, mode) 1446 rtx x; 1447 unsigned hash; 1448 enum machine_mode mode; 1449{ 1450 struct table_elt *p; 1451 1452 for (p = table[hash]; p; p = p->next_same_hash) 1453 if (mode == p->mode && ((x == p->exp && GET_CODE (x) == REG) 1454 || exp_equiv_p (x, p->exp, GET_CODE (x) != REG, 0))) 1455 return p; 1456 1457 return 0; 1458} 1459 1460/* Like `lookup' but don't care whether the table element uses invalid regs. 1461 Also ignore discrepancies in the machine mode of a register. */ 1462 1463static struct table_elt * 1464lookup_for_remove (x, hash, mode) 1465 rtx x; 1466 unsigned hash; 1467 enum machine_mode mode; 1468{ 1469 struct table_elt *p; 1470 1471 if (GET_CODE (x) == REG) 1472 { 1473 unsigned int regno = REGNO (x); 1474 1475 /* Don't check the machine mode when comparing registers; 1476 invalidating (REG:SI 0) also invalidates (REG:DF 0). */ 1477 for (p = table[hash]; p; p = p->next_same_hash) 1478 if (GET_CODE (p->exp) == REG 1479 && REGNO (p->exp) == regno) 1480 return p; 1481 } 1482 else 1483 { 1484 for (p = table[hash]; p; p = p->next_same_hash) 1485 if (mode == p->mode && (x == p->exp || exp_equiv_p (x, p->exp, 0, 0))) 1486 return p; 1487 } 1488 1489 return 0; 1490} 1491 1492/* Look for an expression equivalent to X and with code CODE. 1493 If one is found, return that expression. */ 1494 1495static rtx 1496lookup_as_function (x, code) 1497 rtx x; 1498 enum rtx_code code; 1499{ 1500 struct table_elt *p 1501 = lookup (x, safe_hash (x, VOIDmode) & HASH_MASK, GET_MODE (x)); 1502 1503 /* If we are looking for a CONST_INT, the mode doesn't really matter, as 1504 long as we are narrowing. So if we looked in vain for a mode narrower 1505 than word_mode before, look for word_mode now. */ 1506 if (p == 0 && code == CONST_INT 1507 && GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (word_mode)) 1508 { 1509 x = copy_rtx (x); 1510 PUT_MODE (x, word_mode); 1511 p = lookup (x, safe_hash (x, VOIDmode) & HASH_MASK, word_mode); 1512 } 1513 1514 if (p == 0) 1515 return 0; 1516 1517 for (p = p->first_same_value; p; p = p->next_same_value) 1518 if (GET_CODE (p->exp) == code 1519 /* Make sure this is a valid entry in the table. */ 1520 && exp_equiv_p (p->exp, p->exp, 1, 0)) 1521 return p->exp; 1522 1523 return 0; 1524} 1525 1526/* Insert X in the hash table, assuming HASH is its hash code 1527 and CLASSP is an element of the class it should go in 1528 (or 0 if a new class should be made). 1529 It is inserted at the proper position to keep the class in 1530 the order cheapest first. 1531 1532 MODE is the machine-mode of X, or if X is an integer constant 1533 with VOIDmode then MODE is the mode with which X will be used. 1534 1535 For elements of equal cheapness, the most recent one 1536 goes in front, except that the first element in the list 1537 remains first unless a cheaper element is added. The order of 1538 pseudo-registers does not matter, as canon_reg will be called to 1539 find the cheapest when a register is retrieved from the table. 1540 1541 The in_memory field in the hash table element is set to 0. 1542 The caller must set it nonzero if appropriate. 1543 1544 You should call insert_regs (X, CLASSP, MODIFY) before calling here, 1545 and if insert_regs returns a nonzero value 1546 you must then recompute its hash code before calling here. 1547 1548 If necessary, update table showing constant values of quantities. */ 1549 1550#define CHEAPER(X, Y) \ 1551 (preferrable ((X)->cost, (X)->regcost, (Y)->cost, (Y)->regcost) < 0) 1552 1553static struct table_elt * 1554insert (x, classp, hash, mode) 1555 rtx x; 1556 struct table_elt *classp; 1557 unsigned hash; 1558 enum machine_mode mode; 1559{ 1560 struct table_elt *elt; 1561 1562 /* If X is a register and we haven't made a quantity for it, 1563 something is wrong. */ 1564 if (GET_CODE (x) == REG && ! REGNO_QTY_VALID_P (REGNO (x))) 1565 abort (); 1566 1567 /* If X is a hard register, show it is being put in the table. */ 1568 if (GET_CODE (x) == REG && REGNO (x) < FIRST_PSEUDO_REGISTER) 1569 { 1570 unsigned int regno = REGNO (x); 1571 unsigned int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x)); 1572 unsigned int i; 1573 1574 for (i = regno; i < endregno; i++) 1575 SET_HARD_REG_BIT (hard_regs_in_table, i); 1576 } 1577 1578 /* Put an element for X into the right hash bucket. */ 1579 1580 elt = free_element_chain; 1581 if (elt) 1582 free_element_chain = elt->next_same_hash; 1583 else 1584 { 1585 n_elements_made++; 1586 elt = (struct table_elt *) xmalloc (sizeof (struct table_elt)); 1587 } 1588 1589 elt->exp = x; 1590 elt->canon_exp = NULL_RTX; 1591 elt->cost = COST (x); 1592 elt->regcost = approx_reg_cost (x); 1593 elt->next_same_value = 0; 1594 elt->prev_same_value = 0; 1595 elt->next_same_hash = table[hash]; 1596 elt->prev_same_hash = 0; 1597 elt->related_value = 0; 1598 elt->in_memory = 0; 1599 elt->mode = mode; 1600 elt->is_const = (CONSTANT_P (x) 1601 /* GNU C++ takes advantage of this for `this' 1602 (and other const values). */ 1603 || (RTX_UNCHANGING_P (x) 1604 && GET_CODE (x) == REG 1605 && REGNO (x) >= FIRST_PSEUDO_REGISTER) 1606 || FIXED_BASE_PLUS_P (x)); 1607 1608 if (table[hash]) 1609 table[hash]->prev_same_hash = elt; 1610 table[hash] = elt; 1611 1612 /* Put it into the proper value-class. */ 1613 if (classp) 1614 { 1615 classp = classp->first_same_value; 1616 if (CHEAPER (elt, classp)) 1617 /* Insert at the head of the class */ 1618 { 1619 struct table_elt *p; 1620 elt->next_same_value = classp; 1621 classp->prev_same_value = elt; 1622 elt->first_same_value = elt; 1623 1624 for (p = classp; p; p = p->next_same_value) 1625 p->first_same_value = elt; 1626 } 1627 else 1628 { 1629 /* Insert not at head of the class. */ 1630 /* Put it after the last element cheaper than X. */ 1631 struct table_elt *p, *next; 1632 1633 for (p = classp; (next = p->next_same_value) && CHEAPER (next, elt); 1634 p = next); 1635 1636 /* Put it after P and before NEXT. */ 1637 elt->next_same_value = next; 1638 if (next) 1639 next->prev_same_value = elt; 1640 1641 elt->prev_same_value = p; 1642 p->next_same_value = elt; 1643 elt->first_same_value = classp; 1644 } 1645 } 1646 else 1647 elt->first_same_value = elt; 1648 1649 /* If this is a constant being set equivalent to a register or a register 1650 being set equivalent to a constant, note the constant equivalence. 1651 1652 If this is a constant, it cannot be equivalent to a different constant, 1653 and a constant is the only thing that can be cheaper than a register. So 1654 we know the register is the head of the class (before the constant was 1655 inserted). 1656 1657 If this is a register that is not already known equivalent to a 1658 constant, we must check the entire class. 1659 1660 If this is a register that is already known equivalent to an insn, 1661 update the qtys `const_insn' to show that `this_insn' is the latest 1662 insn making that quantity equivalent to the constant. */ 1663 1664 if (elt->is_const && classp && GET_CODE (classp->exp) == REG 1665 && GET_CODE (x) != REG) 1666 { 1667 int exp_q = REG_QTY (REGNO (classp->exp)); 1668 struct qty_table_elem *exp_ent = &qty_table[exp_q]; 1669 1670 exp_ent->const_rtx = gen_lowpart_if_possible (exp_ent->mode, x); 1671 exp_ent->const_insn = this_insn; 1672 } 1673 1674 else if (GET_CODE (x) == REG 1675 && classp 1676 && ! qty_table[REG_QTY (REGNO (x))].const_rtx 1677 && ! elt->is_const) 1678 { 1679 struct table_elt *p; 1680 1681 for (p = classp; p != 0; p = p->next_same_value) 1682 { 1683 if (p->is_const && GET_CODE (p->exp) != REG) 1684 { 1685 int x_q = REG_QTY (REGNO (x)); 1686 struct qty_table_elem *x_ent = &qty_table[x_q]; 1687 1688 x_ent->const_rtx 1689 = gen_lowpart_if_possible (GET_MODE (x), p->exp); 1690 x_ent->const_insn = this_insn; 1691 break; 1692 } 1693 } 1694 } 1695 1696 else if (GET_CODE (x) == REG 1697 && qty_table[REG_QTY (REGNO (x))].const_rtx 1698 && GET_MODE (x) == qty_table[REG_QTY (REGNO (x))].mode) 1699 qty_table[REG_QTY (REGNO (x))].const_insn = this_insn; 1700 1701 /* If this is a constant with symbolic value, 1702 and it has a term with an explicit integer value, 1703 link it up with related expressions. */ 1704 if (GET_CODE (x) == CONST) 1705 { 1706 rtx subexp = get_related_value (x); 1707 unsigned subhash; 1708 struct table_elt *subelt, *subelt_prev; 1709 1710 if (subexp != 0) 1711 { 1712 /* Get the integer-free subexpression in the hash table. */ 1713 subhash = safe_hash (subexp, mode) & HASH_MASK; 1714 subelt = lookup (subexp, subhash, mode); 1715 if (subelt == 0) 1716 subelt = insert (subexp, NULL, subhash, mode); 1717 /* Initialize SUBELT's circular chain if it has none. */ 1718 if (subelt->related_value == 0) 1719 subelt->related_value = subelt; 1720 /* Find the element in the circular chain that precedes SUBELT. */ 1721 subelt_prev = subelt; 1722 while (subelt_prev->related_value != subelt) 1723 subelt_prev = subelt_prev->related_value; 1724 /* Put new ELT into SUBELT's circular chain just before SUBELT. 1725 This way the element that follows SUBELT is the oldest one. */ 1726 elt->related_value = subelt_prev->related_value; 1727 subelt_prev->related_value = elt; 1728 } 1729 } 1730 1731 return elt; 1732} 1733 1734/* Given two equivalence classes, CLASS1 and CLASS2, put all the entries from 1735 CLASS2 into CLASS1. This is done when we have reached an insn which makes 1736 the two classes equivalent. 1737 1738 CLASS1 will be the surviving class; CLASS2 should not be used after this 1739 call. 1740 1741 Any invalid entries in CLASS2 will not be copied. */ 1742 1743static void 1744merge_equiv_classes (class1, class2) 1745 struct table_elt *class1, *class2; 1746{ 1747 struct table_elt *elt, *next, *new; 1748 1749 /* Ensure we start with the head of the classes. */ 1750 class1 = class1->first_same_value; 1751 class2 = class2->first_same_value; 1752 1753 /* If they were already equal, forget it. */ 1754 if (class1 == class2) 1755 return; 1756 1757 for (elt = class2; elt; elt = next) 1758 { 1759 unsigned int hash; 1760 rtx exp = elt->exp; 1761 enum machine_mode mode = elt->mode; 1762 1763 next = elt->next_same_value; 1764 1765 /* Remove old entry, make a new one in CLASS1's class. 1766 Don't do this for invalid entries as we cannot find their 1767 hash code (it also isn't necessary). */ 1768 if (GET_CODE (exp) == REG || exp_equiv_p (exp, exp, 1, 0)) 1769 { 1770 hash_arg_in_memory = 0; 1771 hash = HASH (exp, mode); 1772 1773 if (GET_CODE (exp) == REG) 1774 delete_reg_equiv (REGNO (exp)); 1775 1776 remove_from_table (elt, hash); 1777 1778 if (insert_regs (exp, class1, 0)) 1779 { 1780 rehash_using_reg (exp); 1781 hash = HASH (exp, mode); 1782 } 1783 new = insert (exp, class1, hash, mode); 1784 new->in_memory = hash_arg_in_memory; 1785 } 1786 } 1787} 1788 1789/* Flush the entire hash table. */ 1790 1791static void 1792flush_hash_table () 1793{ 1794 int i; 1795 struct table_elt *p; 1796 1797 for (i = 0; i < HASH_SIZE; i++) 1798 for (p = table[i]; p; p = table[i]) 1799 { 1800 /* Note that invalidate can remove elements 1801 after P in the current hash chain. */ 1802 if (GET_CODE (p->exp) == REG) 1803 invalidate (p->exp, p->mode); 1804 else 1805 remove_from_table (p, i); 1806 } 1807} 1808 1809/* Function called for each rtx to check whether true dependence exist. */ 1810struct check_dependence_data 1811{ 1812 enum machine_mode mode; 1813 rtx exp; 1814}; 1815 1816static int 1817check_dependence (x, data) 1818 rtx *x; 1819 void *data; 1820{ 1821 struct check_dependence_data *d = (struct check_dependence_data *) data; 1822 if (*x && GET_CODE (*x) == MEM) 1823 return true_dependence (d->exp, d->mode, *x, cse_rtx_varies_p); 1824 else 1825 return 0; 1826} 1827 1828/* Remove from the hash table, or mark as invalid, all expressions whose 1829 values could be altered by storing in X. X is a register, a subreg, or 1830 a memory reference with nonvarying address (because, when a memory 1831 reference with a varying address is stored in, all memory references are 1832 removed by invalidate_memory so specific invalidation is superfluous). 1833 FULL_MODE, if not VOIDmode, indicates that this much should be 1834 invalidated instead of just the amount indicated by the mode of X. This 1835 is only used for bitfield stores into memory. 1836 1837 A nonvarying address may be just a register or just a symbol reference, 1838 or it may be either of those plus a numeric offset. */ 1839 1840static void 1841invalidate (x, full_mode) 1842 rtx x; 1843 enum machine_mode full_mode; 1844{ 1845 int i; 1846 struct table_elt *p; 1847 1848 switch (GET_CODE (x)) 1849 { 1850 case REG: 1851 { 1852 /* If X is a register, dependencies on its contents are recorded 1853 through the qty number mechanism. Just change the qty number of 1854 the register, mark it as invalid for expressions that refer to it, 1855 and remove it itself. */ 1856 unsigned int regno = REGNO (x); 1857 unsigned int hash = HASH (x, GET_MODE (x)); 1858 1859 /* Remove REGNO from any quantity list it might be on and indicate 1860 that its value might have changed. If it is a pseudo, remove its 1861 entry from the hash table. 1862 1863 For a hard register, we do the first two actions above for any 1864 additional hard registers corresponding to X. Then, if any of these 1865 registers are in the table, we must remove any REG entries that 1866 overlap these registers. */ 1867 1868 delete_reg_equiv (regno); 1869 REG_TICK (regno)++; 1870 1871 if (regno >= FIRST_PSEUDO_REGISTER) 1872 { 1873 /* Because a register can be referenced in more than one mode, 1874 we might have to remove more than one table entry. */ 1875 struct table_elt *elt; 1876 1877 while ((elt = lookup_for_remove (x, hash, GET_MODE (x)))) 1878 remove_from_table (elt, hash); 1879 } 1880 else 1881 { 1882 HOST_WIDE_INT in_table 1883 = TEST_HARD_REG_BIT (hard_regs_in_table, regno); 1884 unsigned int endregno 1885 = regno + HARD_REGNO_NREGS (regno, GET_MODE (x)); 1886 unsigned int tregno, tendregno, rn; 1887 struct table_elt *p, *next; 1888 1889 CLEAR_HARD_REG_BIT (hard_regs_in_table, regno); 1890 1891 for (rn = regno + 1; rn < endregno; rn++) 1892 { 1893 in_table |= TEST_HARD_REG_BIT (hard_regs_in_table, rn); 1894 CLEAR_HARD_REG_BIT (hard_regs_in_table, rn); 1895 delete_reg_equiv (rn); 1896 REG_TICK (rn)++; 1897 } 1898 1899 if (in_table) 1900 for (hash = 0; hash < HASH_SIZE; hash++) 1901 for (p = table[hash]; p; p = next) 1902 { 1903 next = p->next_same_hash; 1904 1905 if (GET_CODE (p->exp) != REG 1906 || REGNO (p->exp) >= FIRST_PSEUDO_REGISTER) 1907 continue; 1908 1909 tregno = REGNO (p->exp); 1910 tendregno 1911 = tregno + HARD_REGNO_NREGS (tregno, GET_MODE (p->exp)); 1912 if (tendregno > regno && tregno < endregno) 1913 remove_from_table (p, hash); 1914 } 1915 } 1916 } 1917 return; 1918 1919 case SUBREG: 1920 invalidate (SUBREG_REG (x), VOIDmode); 1921 return; 1922 1923 case PARALLEL: 1924 for (i = XVECLEN (x, 0) - 1; i >= 0; --i) 1925 invalidate (XVECEXP (x, 0, i), VOIDmode); 1926 return; 1927 1928 case EXPR_LIST: 1929 /* This is part of a disjoint return value; extract the location in 1930 question ignoring the offset. */ 1931 invalidate (XEXP (x, 0), VOIDmode); 1932 return; 1933 1934 case MEM: 1935 /* Calculate the canonical version of X here so that 1936 true_dependence doesn't generate new RTL for X on each call. */ 1937 x = canon_rtx (x); 1938 1939 /* Remove all hash table elements that refer to overlapping pieces of 1940 memory. */ 1941 if (full_mode == VOIDmode) 1942 full_mode = GET_MODE (x); 1943 1944 for (i = 0; i < HASH_SIZE; i++) 1945 { 1946 struct table_elt *next; 1947 1948 for (p = table[i]; p; p = next) 1949 { 1950 next = p->next_same_hash; 1951 if (p->in_memory) 1952 { 1953 struct check_dependence_data d; 1954 1955 /* Just canonicalize the expression once; 1956 otherwise each time we call invalidate 1957 true_dependence will canonicalize the 1958 expression again. */ 1959 if (!p->canon_exp) 1960 p->canon_exp = canon_rtx (p->exp); 1961 d.exp = x; 1962 d.mode = full_mode; 1963 if (for_each_rtx (&p->canon_exp, check_dependence, &d)) 1964 remove_from_table (p, i); 1965 } 1966 } 1967 } 1968 return; 1969 1970 default: 1971 abort (); 1972 } 1973} 1974 1975/* Remove all expressions that refer to register REGNO, 1976 since they are already invalid, and we are about to 1977 mark that register valid again and don't want the old 1978 expressions to reappear as valid. */ 1979 1980static void 1981remove_invalid_refs (regno) 1982 unsigned int regno; 1983{ 1984 unsigned int i; 1985 struct table_elt *p, *next; 1986 1987 for (i = 0; i < HASH_SIZE; i++) 1988 for (p = table[i]; p; p = next) 1989 { 1990 next = p->next_same_hash; 1991 if (GET_CODE (p->exp) != REG 1992 && refers_to_regno_p (regno, regno + 1, p->exp, (rtx*) 0)) 1993 remove_from_table (p, i); 1994 } 1995} 1996 1997/* Likewise for a subreg with subreg_reg REGNO, subreg_byte OFFSET, 1998 and mode MODE. */ 1999static void 2000remove_invalid_subreg_refs (regno, offset, mode) 2001 unsigned int regno; 2002 unsigned int offset; 2003 enum machine_mode mode; 2004{ 2005 unsigned int i; 2006 struct table_elt *p, *next; 2007 unsigned int end = offset + (GET_MODE_SIZE (mode) - 1); 2008 2009 for (i = 0; i < HASH_SIZE; i++) 2010 for (p = table[i]; p; p = next) 2011 { 2012 rtx exp = p->exp; 2013 next = p->next_same_hash; 2014 2015 if (GET_CODE (exp) != REG 2016 && (GET_CODE (exp) != SUBREG 2017 || GET_CODE (SUBREG_REG (exp)) != REG 2018 || REGNO (SUBREG_REG (exp)) != regno 2019 || (((SUBREG_BYTE (exp) 2020 + (GET_MODE_SIZE (GET_MODE (exp)) - 1)) >= offset) 2021 && SUBREG_BYTE (exp) <= end)) 2022 && refers_to_regno_p (regno, regno + 1, p->exp, (rtx*) 0)) 2023 remove_from_table (p, i); 2024 } 2025} 2026 2027/* Recompute the hash codes of any valid entries in the hash table that 2028 reference X, if X is a register, or SUBREG_REG (X) if X is a SUBREG. 2029 2030 This is called when we make a jump equivalence. */ 2031 2032static void 2033rehash_using_reg (x) 2034 rtx x; 2035{ 2036 unsigned int i; 2037 struct table_elt *p, *next; 2038 unsigned hash; 2039 2040 if (GET_CODE (x) == SUBREG) 2041 x = SUBREG_REG (x); 2042 2043 /* If X is not a register or if the register is known not to be in any 2044 valid entries in the table, we have no work to do. */ 2045 2046 if (GET_CODE (x) != REG 2047 || REG_IN_TABLE (REGNO (x)) < 0 2048 || REG_IN_TABLE (REGNO (x)) != REG_TICK (REGNO (x))) 2049 return; 2050 2051 /* Scan all hash chains looking for valid entries that mention X. 2052 If we find one and it is in the wrong hash chain, move it. We can skip 2053 objects that are registers, since they are handled specially. */ 2054 2055 for (i = 0; i < HASH_SIZE; i++) 2056 for (p = table[i]; p; p = next) 2057 { 2058 next = p->next_same_hash; 2059 if (GET_CODE (p->exp) != REG && reg_mentioned_p (x, p->exp) 2060 && exp_equiv_p (p->exp, p->exp, 1, 0) 2061 && i != (hash = safe_hash (p->exp, p->mode) & HASH_MASK)) 2062 { 2063 if (p->next_same_hash) 2064 p->next_same_hash->prev_same_hash = p->prev_same_hash; 2065 2066 if (p->prev_same_hash) 2067 p->prev_same_hash->next_same_hash = p->next_same_hash; 2068 else 2069 table[i] = p->next_same_hash; 2070 2071 p->next_same_hash = table[hash]; 2072 p->prev_same_hash = 0; 2073 if (table[hash]) 2074 table[hash]->prev_same_hash = p; 2075 table[hash] = p; 2076 } 2077 } 2078} 2079 2080/* Remove from the hash table any expression that is a call-clobbered 2081 register. Also update their TICK values. */ 2082 2083static void 2084invalidate_for_call () 2085{ 2086 unsigned int regno, endregno; 2087 unsigned int i; 2088 unsigned hash; 2089 struct table_elt *p, *next; 2090 int in_table = 0; 2091 2092 /* Go through all the hard registers. For each that is clobbered in 2093 a CALL_INSN, remove the register from quantity chains and update 2094 reg_tick if defined. Also see if any of these registers is currently 2095 in the table. */ 2096 2097 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) 2098 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)) 2099 { 2100 delete_reg_equiv (regno); 2101 if (REG_TICK (regno) >= 0) 2102 REG_TICK (regno)++; 2103 2104 in_table |= (TEST_HARD_REG_BIT (hard_regs_in_table, regno) != 0); 2105 } 2106 2107 /* In the case where we have no call-clobbered hard registers in the 2108 table, we are done. Otherwise, scan the table and remove any 2109 entry that overlaps a call-clobbered register. */ 2110 2111 if (in_table) 2112 for (hash = 0; hash < HASH_SIZE; hash++) 2113 for (p = table[hash]; p; p = next) 2114 { 2115 next = p->next_same_hash; 2116 2117 if (GET_CODE (p->exp) != REG 2118 || REGNO (p->exp) >= FIRST_PSEUDO_REGISTER) 2119 continue; 2120 2121 regno = REGNO (p->exp); 2122 endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (p->exp)); 2123 2124 for (i = regno; i < endregno; i++) 2125 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) 2126 { 2127 remove_from_table (p, hash); 2128 break; 2129 } 2130 } 2131} 2132 2133/* Given an expression X of type CONST, 2134 and ELT which is its table entry (or 0 if it 2135 is not in the hash table), 2136 return an alternate expression for X as a register plus integer. 2137 If none can be found, return 0. */ 2138 2139static rtx 2140use_related_value (x, elt) 2141 rtx x; 2142 struct table_elt *elt; 2143{ 2144 struct table_elt *relt = 0; 2145 struct table_elt *p, *q; 2146 HOST_WIDE_INT offset; 2147 2148 /* First, is there anything related known? 2149 If we have a table element, we can tell from that. 2150 Otherwise, must look it up. */ 2151 2152 if (elt != 0 && elt->related_value != 0) 2153 relt = elt; 2154 else if (elt == 0 && GET_CODE (x) == CONST) 2155 { 2156 rtx subexp = get_related_value (x); 2157 if (subexp != 0) 2158 relt = lookup (subexp, 2159 safe_hash (subexp, GET_MODE (subexp)) & HASH_MASK, 2160 GET_MODE (subexp)); 2161 } 2162 2163 if (relt == 0) 2164 return 0; 2165 2166 /* Search all related table entries for one that has an 2167 equivalent register. */ 2168 2169 p = relt; 2170 while (1) 2171 { 2172 /* This loop is strange in that it is executed in two different cases. 2173 The first is when X is already in the table. Then it is searching 2174 the RELATED_VALUE list of X's class (RELT). The second case is when 2175 X is not in the table. Then RELT points to a class for the related 2176 value. 2177 2178 Ensure that, whatever case we are in, that we ignore classes that have 2179 the same value as X. */ 2180 2181 if (rtx_equal_p (x, p->exp)) 2182 q = 0; 2183 else 2184 for (q = p->first_same_value; q; q = q->next_same_value) 2185 if (GET_CODE (q->exp) == REG) 2186 break; 2187 2188 if (q) 2189 break; 2190 2191 p = p->related_value; 2192 2193 /* We went all the way around, so there is nothing to be found. 2194 Alternatively, perhaps RELT was in the table for some other reason 2195 and it has no related values recorded. */ 2196 if (p == relt || p == 0) 2197 break; 2198 } 2199 2200 if (q == 0) 2201 return 0; 2202 2203 offset = (get_integer_term (x) - get_integer_term (p->exp)); 2204 /* Note: OFFSET may be 0 if P->xexp and X are related by commutativity. */ 2205 return plus_constant (q->exp, offset); 2206} 2207 2208/* Hash a string. Just add its bytes up. */ 2209static inline unsigned 2210canon_hash_string (ps) 2211 const char *ps; 2212{ 2213 unsigned hash = 0; 2214 const unsigned char *p = (const unsigned char *)ps; 2215 2216 if (p) 2217 while (*p) 2218 hash += *p++; 2219 2220 return hash; 2221} 2222 2223/* Hash an rtx. We are careful to make sure the value is never negative. 2224 Equivalent registers hash identically. 2225 MODE is used in hashing for CONST_INTs only; 2226 otherwise the mode of X is used. 2227 2228 Store 1 in do_not_record if any subexpression is volatile. 2229 2230 Store 1 in hash_arg_in_memory if X contains a MEM rtx 2231 which does not have the RTX_UNCHANGING_P bit set. 2232 2233 Note that cse_insn knows that the hash code of a MEM expression 2234 is just (int) MEM plus the hash code of the address. */ 2235 2236static unsigned 2237canon_hash (x, mode) 2238 rtx x; 2239 enum machine_mode mode; 2240{ 2241 int i, j; 2242 unsigned hash = 0; 2243 enum rtx_code code; 2244 const char *fmt; 2245 2246 /* repeat is used to turn tail-recursion into iteration. */ 2247 repeat: 2248 if (x == 0) 2249 return hash; 2250 2251 code = GET_CODE (x); 2252 switch (code) 2253 { 2254 case REG: 2255 { 2256 unsigned int regno = REGNO (x); 2257 2258 /* On some machines, we can't record any non-fixed hard register, 2259 because extending its life will cause reload problems. We 2260 consider ap, fp, and sp to be fixed for this purpose. 2261 2262 We also consider CCmode registers to be fixed for this purpose; 2263 failure to do so leads to failure to simplify 0<100 type of 2264 conditionals. 2265 2266 On all machines, we can't record any global registers. 2267 Nor should we record any register that is in a small 2268 class, as defined by CLASS_LIKELY_SPILLED_P. */ 2269 2270 if (regno < FIRST_PSEUDO_REGISTER 2271 && (global_regs[regno] 2272 || CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (regno)) 2273 || (SMALL_REGISTER_CLASSES 2274 && ! fixed_regs[regno] 2275 && x != frame_pointer_rtx 2276 && x != hard_frame_pointer_rtx 2277 && x != arg_pointer_rtx 2278 && x != stack_pointer_rtx 2279 && GET_MODE_CLASS (GET_MODE (x)) != MODE_CC))) 2280 { 2281 do_not_record = 1; 2282 return 0; 2283 } 2284 2285 hash += ((unsigned) REG << 7) + (unsigned) REG_QTY (regno); 2286 return hash; 2287 } 2288 2289 /* We handle SUBREG of a REG specially because the underlying 2290 reg changes its hash value with every value change; we don't 2291 want to have to forget unrelated subregs when one subreg changes. */ 2292 case SUBREG: 2293 { 2294 if (GET_CODE (SUBREG_REG (x)) == REG) 2295 { 2296 hash += (((unsigned) SUBREG << 7) 2297 + REGNO (SUBREG_REG (x)) 2298 + (SUBREG_BYTE (x) / UNITS_PER_WORD)); 2299 return hash; 2300 } 2301 break; 2302 } 2303 2304 case CONST_INT: 2305 { 2306 unsigned HOST_WIDE_INT tem = INTVAL (x); 2307 hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem; 2308 return hash; 2309 } 2310 2311 case CONST_DOUBLE: 2312 /* This is like the general case, except that it only counts 2313 the integers representing the constant. */ 2314 hash += (unsigned) code + (unsigned) GET_MODE (x); 2315 if (GET_MODE (x) != VOIDmode) 2316 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++) 2317 { 2318 unsigned HOST_WIDE_INT tem = XWINT (x, i); 2319 hash += tem; 2320 } 2321 else 2322 hash += ((unsigned) CONST_DOUBLE_LOW (x) 2323 + (unsigned) CONST_DOUBLE_HIGH (x)); 2324 return hash; 2325 2326 /* Assume there is only one rtx object for any given label. */ 2327 case LABEL_REF: 2328 hash += ((unsigned) LABEL_REF << 7) + (unsigned long) XEXP (x, 0); 2329 return hash; 2330 2331 case SYMBOL_REF: 2332 hash += ((unsigned) SYMBOL_REF << 7) + (unsigned long) XSTR (x, 0); 2333 return hash; 2334 2335 case MEM: 2336 /* We don't record if marked volatile or if BLKmode since we don't 2337 know the size of the move. */ 2338 if (MEM_VOLATILE_P (x) || GET_MODE (x) == BLKmode) 2339 { 2340 do_not_record = 1; 2341 return 0; 2342 } 2343 if (! RTX_UNCHANGING_P (x) || FIXED_BASE_PLUS_P (XEXP (x, 0))) 2344 { 2345 hash_arg_in_memory = 1; 2346 } 2347 /* Now that we have already found this special case, 2348 might as well speed it up as much as possible. */ 2349 hash += (unsigned) MEM; 2350 x = XEXP (x, 0); 2351 goto repeat; 2352 2353 case USE: 2354 /* A USE that mentions non-volatile memory needs special 2355 handling since the MEM may be BLKmode which normally 2356 prevents an entry from being made. Pure calls are 2357 marked by a USE which mentions BLKmode memory. */ 2358 if (GET_CODE (XEXP (x, 0)) == MEM 2359 && ! MEM_VOLATILE_P (XEXP (x, 0))) 2360 { 2361 hash += (unsigned)USE; 2362 x = XEXP (x, 0); 2363 2364 if (! RTX_UNCHANGING_P (x) || FIXED_BASE_PLUS_P (XEXP (x, 0))) 2365 hash_arg_in_memory = 1; 2366 2367 /* Now that we have already found this special case, 2368 might as well speed it up as much as possible. */ 2369 hash += (unsigned) MEM; 2370 x = XEXP (x, 0); 2371 goto repeat; 2372 } 2373 break; 2374 2375 case PRE_DEC: 2376 case PRE_INC: 2377 case POST_DEC: 2378 case POST_INC: 2379 case PRE_MODIFY: 2380 case POST_MODIFY: 2381 case PC: 2382 case CC0: 2383 case CALL: 2384 case UNSPEC_VOLATILE: 2385 do_not_record = 1; 2386 return 0; 2387 2388 case ASM_OPERANDS: 2389 if (MEM_VOLATILE_P (x)) 2390 { 2391 do_not_record = 1; 2392 return 0; 2393 } 2394 else 2395 { 2396 /* We don't want to take the filename and line into account. */ 2397 hash += (unsigned) code + (unsigned) GET_MODE (x) 2398 + canon_hash_string (ASM_OPERANDS_TEMPLATE (x)) 2399 + canon_hash_string (ASM_OPERANDS_OUTPUT_CONSTRAINT (x)) 2400 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x); 2401 2402 if (ASM_OPERANDS_INPUT_LENGTH (x)) 2403 { 2404 for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++) 2405 { 2406 hash += (canon_hash (ASM_OPERANDS_INPUT (x, i), 2407 GET_MODE (ASM_OPERANDS_INPUT (x, i))) 2408 + canon_hash_string (ASM_OPERANDS_INPUT_CONSTRAINT 2409 (x, i))); 2410 } 2411 2412 hash += canon_hash_string (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0)); 2413 x = ASM_OPERANDS_INPUT (x, 0); 2414 mode = GET_MODE (x); 2415 goto repeat; 2416 } 2417 2418 return hash; 2419 } 2420 break; 2421 2422 default: 2423 break; 2424 } 2425 2426 i = GET_RTX_LENGTH (code) - 1; 2427 hash += (unsigned) code + (unsigned) GET_MODE (x); 2428 fmt = GET_RTX_FORMAT (code); 2429 for (; i >= 0; i--) 2430 { 2431 if (fmt[i] == 'e') 2432 { 2433 rtx tem = XEXP (x, i); 2434 2435 /* If we are about to do the last recursive call 2436 needed at this level, change it into iteration. 2437 This function is called enough to be worth it. */ 2438 if (i == 0) 2439 { 2440 x = tem; 2441 goto repeat; 2442 } 2443 hash += canon_hash (tem, 0); 2444 } 2445 else if (fmt[i] == 'E') 2446 for (j = 0; j < XVECLEN (x, i); j++) 2447 hash += canon_hash (XVECEXP (x, i, j), 0); 2448 else if (fmt[i] == 's') 2449 hash += canon_hash_string (XSTR (x, i)); 2450 else if (fmt[i] == 'i') 2451 { 2452 unsigned tem = XINT (x, i); 2453 hash += tem; 2454 } 2455 else if (fmt[i] == '0' || fmt[i] == 't') 2456 /* Unused. */ 2457 ; 2458 else 2459 abort (); 2460 } 2461 return hash; 2462} 2463 2464/* Like canon_hash but with no side effects. */ 2465 2466static unsigned 2467safe_hash (x, mode) 2468 rtx x; 2469 enum machine_mode mode; 2470{ 2471 int save_do_not_record = do_not_record; 2472 int save_hash_arg_in_memory = hash_arg_in_memory; 2473 unsigned hash = canon_hash (x, mode); 2474 hash_arg_in_memory = save_hash_arg_in_memory; 2475 do_not_record = save_do_not_record; 2476 return hash; 2477} 2478 2479/* Return 1 iff X and Y would canonicalize into the same thing, 2480 without actually constructing the canonicalization of either one. 2481 If VALIDATE is nonzero, 2482 we assume X is an expression being processed from the rtl 2483 and Y was found in the hash table. We check register refs 2484 in Y for being marked as valid. 2485 2486 If EQUAL_VALUES is nonzero, we allow a register to match a constant value 2487 that is known to be in the register. Ordinarily, we don't allow them 2488 to match, because letting them match would cause unpredictable results 2489 in all the places that search a hash table chain for an equivalent 2490 for a given value. A possible equivalent that has different structure 2491 has its hash code computed from different data. Whether the hash code 2492 is the same as that of the given value is pure luck. */ 2493 2494static int 2495exp_equiv_p (x, y, validate, equal_values) 2496 rtx x, y; 2497 int validate; 2498 int equal_values; 2499{ 2500 int i, j; 2501 enum rtx_code code; 2502 const char *fmt; 2503 2504 /* Note: it is incorrect to assume an expression is equivalent to itself 2505 if VALIDATE is nonzero. */ 2506 if (x == y && !validate) 2507 return 1; 2508 if (x == 0 || y == 0) 2509 return x == y; 2510 2511 code = GET_CODE (x); 2512 if (code != GET_CODE (y)) 2513 { 2514 if (!equal_values) 2515 return 0; 2516 2517 /* If X is a constant and Y is a register or vice versa, they may be 2518 equivalent. We only have to validate if Y is a register. */ 2519 if (CONSTANT_P (x) && GET_CODE (y) == REG 2520 && REGNO_QTY_VALID_P (REGNO (y))) 2521 { 2522 int y_q = REG_QTY (REGNO (y)); 2523 struct qty_table_elem *y_ent = &qty_table[y_q]; 2524 2525 if (GET_MODE (y) == y_ent->mode 2526 && rtx_equal_p (x, y_ent->const_rtx) 2527 && (! validate || REG_IN_TABLE (REGNO (y)) == REG_TICK (REGNO (y)))) 2528 return 1; 2529 } 2530 2531 if (CONSTANT_P (y) && code == REG 2532 && REGNO_QTY_VALID_P (REGNO (x))) 2533 { 2534 int x_q = REG_QTY (REGNO (x)); 2535 struct qty_table_elem *x_ent = &qty_table[x_q]; 2536 2537 if (GET_MODE (x) == x_ent->mode 2538 && rtx_equal_p (y, x_ent->const_rtx)) 2539 return 1; 2540 } 2541 2542 return 0; 2543 } 2544 2545 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ 2546 if (GET_MODE (x) != GET_MODE (y)) 2547 return 0; 2548 2549 switch (code) 2550 { 2551 case PC: 2552 case CC0: 2553 case CONST_INT: 2554 return x == y; 2555 2556 case LABEL_REF: 2557 return XEXP (x, 0) == XEXP (y, 0); 2558 2559 case SYMBOL_REF: 2560 return XSTR (x, 0) == XSTR (y, 0); 2561 2562 case REG: 2563 { 2564 unsigned int regno = REGNO (y); 2565 unsigned int endregno 2566 = regno + (regno >= FIRST_PSEUDO_REGISTER ? 1 2567 : HARD_REGNO_NREGS (regno, GET_MODE (y))); 2568 unsigned int i; 2569 2570 /* If the quantities are not the same, the expressions are not 2571 equivalent. If there are and we are not to validate, they 2572 are equivalent. Otherwise, ensure all regs are up-to-date. */ 2573 2574 if (REG_QTY (REGNO (x)) != REG_QTY (regno)) 2575 return 0; 2576 2577 if (! validate) 2578 return 1; 2579 2580 for (i = regno; i < endregno; i++) 2581 if (REG_IN_TABLE (i) != REG_TICK (i)) 2582 return 0; 2583 2584 return 1; 2585 } 2586 2587 /* For commutative operations, check both orders. */ 2588 case PLUS: 2589 case MULT: 2590 case AND: 2591 case IOR: 2592 case XOR: 2593 case NE: 2594 case EQ: 2595 return ((exp_equiv_p (XEXP (x, 0), XEXP (y, 0), validate, equal_values) 2596 && exp_equiv_p (XEXP (x, 1), XEXP (y, 1), 2597 validate, equal_values)) 2598 || (exp_equiv_p (XEXP (x, 0), XEXP (y, 1), 2599 validate, equal_values) 2600 && exp_equiv_p (XEXP (x, 1), XEXP (y, 0), 2601 validate, equal_values))); 2602 2603 case ASM_OPERANDS: 2604 /* We don't use the generic code below because we want to 2605 disregard filename and line numbers. */ 2606 2607 /* A volatile asm isn't equivalent to any other. */ 2608 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y)) 2609 return 0; 2610 2611 if (GET_MODE (x) != GET_MODE (y) 2612 || strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y)) 2613 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x), 2614 ASM_OPERANDS_OUTPUT_CONSTRAINT (y)) 2615 || ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y) 2616 || ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y)) 2617 return 0; 2618 2619 if (ASM_OPERANDS_INPUT_LENGTH (x)) 2620 { 2621 for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--) 2622 if (! exp_equiv_p (ASM_OPERANDS_INPUT (x, i), 2623 ASM_OPERANDS_INPUT (y, i), 2624 validate, equal_values) 2625 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i), 2626 ASM_OPERANDS_INPUT_CONSTRAINT (y, i))) 2627 return 0; 2628 } 2629 2630 return 1; 2631 2632 default: 2633 break; 2634 } 2635 2636 /* Compare the elements. If any pair of corresponding elements 2637 fail to match, return 0 for the whole things. */ 2638 2639 fmt = GET_RTX_FORMAT (code); 2640 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 2641 { 2642 switch (fmt[i]) 2643 { 2644 case 'e': 2645 if (! exp_equiv_p (XEXP (x, i), XEXP (y, i), validate, equal_values)) 2646 return 0; 2647 break; 2648 2649 case 'E': 2650 if (XVECLEN (x, i) != XVECLEN (y, i)) 2651 return 0; 2652 for (j = 0; j < XVECLEN (x, i); j++) 2653 if (! exp_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j), 2654 validate, equal_values)) 2655 return 0; 2656 break; 2657 2658 case 's': 2659 if (strcmp (XSTR (x, i), XSTR (y, i))) 2660 return 0; 2661 break; 2662 2663 case 'i': 2664 if (XINT (x, i) != XINT (y, i)) 2665 return 0; 2666 break; 2667 2668 case 'w': 2669 if (XWINT (x, i) != XWINT (y, i)) 2670 return 0; 2671 break; 2672 2673 case '0': 2674 case 't': 2675 break; 2676 2677 default: 2678 abort (); 2679 } 2680 } 2681 2682 return 1; 2683} 2684 2685/* Return 1 if X has a value that can vary even between two 2686 executions of the program. 0 means X can be compared reliably 2687 against certain constants or near-constants. */ 2688 2689static int 2690cse_rtx_varies_p (x, from_alias) 2691 rtx x; 2692 int from_alias; 2693{ 2694 /* We need not check for X and the equivalence class being of the same 2695 mode because if X is equivalent to a constant in some mode, it 2696 doesn't vary in any mode. */ 2697 2698 if (GET_CODE (x) == REG 2699 && REGNO_QTY_VALID_P (REGNO (x))) 2700 { 2701 int x_q = REG_QTY (REGNO (x)); 2702 struct qty_table_elem *x_ent = &qty_table[x_q]; 2703 2704 if (GET_MODE (x) == x_ent->mode 2705 && x_ent->const_rtx != NULL_RTX) 2706 return 0; 2707 } 2708 2709 if (GET_CODE (x) == PLUS 2710 && GET_CODE (XEXP (x, 1)) == CONST_INT 2711 && GET_CODE (XEXP (x, 0)) == REG 2712 && REGNO_QTY_VALID_P (REGNO (XEXP (x, 0)))) 2713 { 2714 int x0_q = REG_QTY (REGNO (XEXP (x, 0))); 2715 struct qty_table_elem *x0_ent = &qty_table[x0_q]; 2716 2717 if ((GET_MODE (XEXP (x, 0)) == x0_ent->mode) 2718 && x0_ent->const_rtx != NULL_RTX) 2719 return 0; 2720 } 2721 2722 /* This can happen as the result of virtual register instantiation, if 2723 the initial constant is too large to be a valid address. This gives 2724 us a three instruction sequence, load large offset into a register, 2725 load fp minus a constant into a register, then a MEM which is the 2726 sum of the two `constant' registers. */ 2727 if (GET_CODE (x) == PLUS 2728 && GET_CODE (XEXP (x, 0)) == REG 2729 && GET_CODE (XEXP (x, 1)) == REG 2730 && REGNO_QTY_VALID_P (REGNO (XEXP (x, 0))) 2731 && REGNO_QTY_VALID_P (REGNO (XEXP (x, 1)))) 2732 { 2733 int x0_q = REG_QTY (REGNO (XEXP (x, 0))); 2734 int x1_q = REG_QTY (REGNO (XEXP (x, 1))); 2735 struct qty_table_elem *x0_ent = &qty_table[x0_q]; 2736 struct qty_table_elem *x1_ent = &qty_table[x1_q]; 2737 2738 if ((GET_MODE (XEXP (x, 0)) == x0_ent->mode) 2739 && x0_ent->const_rtx != NULL_RTX 2740 && (GET_MODE (XEXP (x, 1)) == x1_ent->mode) 2741 && x1_ent->const_rtx != NULL_RTX) 2742 return 0; 2743 } 2744 2745 return rtx_varies_p (x, from_alias); 2746} 2747 2748/* Canonicalize an expression: 2749 replace each register reference inside it 2750 with the "oldest" equivalent register. 2751 2752 If INSN is non-zero and we are replacing a pseudo with a hard register 2753 or vice versa, validate_change is used to ensure that INSN remains valid 2754 after we make our substitution. The calls are made with IN_GROUP non-zero 2755 so apply_change_group must be called upon the outermost return from this 2756 function (unless INSN is zero). The result of apply_change_group can 2757 generally be discarded since the changes we are making are optional. */ 2758 2759static rtx 2760canon_reg (x, insn) 2761 rtx x; 2762 rtx insn; 2763{ 2764 int i; 2765 enum rtx_code code; 2766 const char *fmt; 2767 2768 if (x == 0) 2769 return x; 2770 2771 code = GET_CODE (x); 2772 switch (code) 2773 { 2774 case PC: 2775 case CC0: 2776 case CONST: 2777 case CONST_INT: 2778 case CONST_DOUBLE: 2779 case SYMBOL_REF: 2780 case LABEL_REF: 2781 case ADDR_VEC: 2782 case ADDR_DIFF_VEC: 2783 return x; 2784 2785 case REG: 2786 { 2787 int first; 2788 int q; 2789 struct qty_table_elem *ent; 2790 2791 /* Never replace a hard reg, because hard regs can appear 2792 in more than one machine mode, and we must preserve the mode 2793 of each occurrence. Also, some hard regs appear in 2794 MEMs that are shared and mustn't be altered. Don't try to 2795 replace any reg that maps to a reg of class NO_REGS. */ 2796 if (REGNO (x) < FIRST_PSEUDO_REGISTER 2797 || ! REGNO_QTY_VALID_P (REGNO (x))) 2798 return x; 2799 2800 q = REG_QTY (REGNO (x)); 2801 ent = &qty_table[q]; 2802 first = ent->first_reg; 2803 return (first >= FIRST_PSEUDO_REGISTER ? regno_reg_rtx[first] 2804 : REGNO_REG_CLASS (first) == NO_REGS ? x 2805 : gen_rtx_REG (ent->mode, first)); 2806 } 2807 2808 default: 2809 break; 2810 } 2811 2812 fmt = GET_RTX_FORMAT (code); 2813 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 2814 { 2815 int j; 2816 2817 if (fmt[i] == 'e') 2818 { 2819 rtx new = canon_reg (XEXP (x, i), insn); 2820 int insn_code; 2821 2822 /* If replacing pseudo with hard reg or vice versa, ensure the 2823 insn remains valid. Likewise if the insn has MATCH_DUPs. */ 2824 if (insn != 0 && new != 0 2825 && GET_CODE (new) == REG && GET_CODE (XEXP (x, i)) == REG 2826 && (((REGNO (new) < FIRST_PSEUDO_REGISTER) 2827 != (REGNO (XEXP (x, i)) < FIRST_PSEUDO_REGISTER)) 2828 || (insn_code = recog_memoized (insn)) < 0 2829 || insn_data[insn_code].n_dups > 0)) 2830 validate_change (insn, &XEXP (x, i), new, 1); 2831 else 2832 XEXP (x, i) = new; 2833 } 2834 else if (fmt[i] == 'E') 2835 for (j = 0; j < XVECLEN (x, i); j++) 2836 XVECEXP (x, i, j) = canon_reg (XVECEXP (x, i, j), insn); 2837 } 2838 2839 return x; 2840} 2841 2842/* LOC is a location within INSN that is an operand address (the contents of 2843 a MEM). Find the best equivalent address to use that is valid for this 2844 insn. 2845 2846 On most CISC machines, complicated address modes are costly, and rtx_cost 2847 is a good approximation for that cost. However, most RISC machines have 2848 only a few (usually only one) memory reference formats. If an address is 2849 valid at all, it is often just as cheap as any other address. Hence, for 2850 RISC machines, we use the configuration macro `ADDRESS_COST' to compare the 2851 costs of various addresses. For two addresses of equal cost, choose the one 2852 with the highest `rtx_cost' value as that has the potential of eliminating 2853 the most insns. For equal costs, we choose the first in the equivalence 2854 class. Note that we ignore the fact that pseudo registers are cheaper 2855 than hard registers here because we would also prefer the pseudo registers. 2856 */ 2857 2858static void 2859find_best_addr (insn, loc, mode) 2860 rtx insn; 2861 rtx *loc; 2862 enum machine_mode mode; 2863{ 2864 struct table_elt *elt; 2865 rtx addr = *loc; 2866#ifdef ADDRESS_COST 2867 struct table_elt *p; 2868 int found_better = 1; 2869#endif 2870 int save_do_not_record = do_not_record; 2871 int save_hash_arg_in_memory = hash_arg_in_memory; 2872 int addr_volatile; 2873 int regno; 2874 unsigned hash; 2875 2876 /* Do not try to replace constant addresses or addresses of local and 2877 argument slots. These MEM expressions are made only once and inserted 2878 in many instructions, as well as being used to control symbol table 2879 output. It is not safe to clobber them. 2880 2881 There are some uncommon cases where the address is already in a register 2882 for some reason, but we cannot take advantage of that because we have 2883 no easy way to unshare the MEM. In addition, looking up all stack 2884 addresses is costly. */ 2885 if ((GET_CODE (addr) == PLUS 2886 && GET_CODE (XEXP (addr, 0)) == REG 2887 && GET_CODE (XEXP (addr, 1)) == CONST_INT 2888 && (regno = REGNO (XEXP (addr, 0)), 2889 regno == FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM 2890 || regno == ARG_POINTER_REGNUM)) 2891 || (GET_CODE (addr) == REG 2892 && (regno = REGNO (addr), regno == FRAME_POINTER_REGNUM 2893 || regno == HARD_FRAME_POINTER_REGNUM 2894 || regno == ARG_POINTER_REGNUM)) 2895 || GET_CODE (addr) == ADDRESSOF 2896 || CONSTANT_ADDRESS_P (addr)) 2897 return; 2898 2899 /* If this address is not simply a register, try to fold it. This will 2900 sometimes simplify the expression. Many simplifications 2901 will not be valid, but some, usually applying the associative rule, will 2902 be valid and produce better code. */ 2903 if (GET_CODE (addr) != REG) 2904 { 2905 rtx folded = fold_rtx (copy_rtx (addr), NULL_RTX); 2906 int addr_folded_cost = address_cost (folded, mode); 2907 int addr_cost = address_cost (addr, mode); 2908 2909 if ((addr_folded_cost < addr_cost 2910 || (addr_folded_cost == addr_cost 2911 /* ??? The rtx_cost comparison is left over from an older 2912 version of this code. It is probably no longer helpful. */ 2913 && (rtx_cost (folded, MEM) > rtx_cost (addr, MEM) 2914 || approx_reg_cost (folded) < approx_reg_cost (addr)))) 2915 && validate_change (insn, loc, folded, 0)) 2916 addr = folded; 2917 } 2918 2919 /* If this address is not in the hash table, we can't look for equivalences 2920 of the whole address. Also, ignore if volatile. */ 2921 2922 do_not_record = 0; 2923 hash = HASH (addr, Pmode); 2924 addr_volatile = do_not_record; 2925 do_not_record = save_do_not_record; 2926 hash_arg_in_memory = save_hash_arg_in_memory; 2927 2928 if (addr_volatile) 2929 return; 2930 2931 elt = lookup (addr, hash, Pmode); 2932 2933#ifndef ADDRESS_COST 2934 if (elt) 2935 { 2936 int our_cost = elt->cost; 2937 2938 /* Find the lowest cost below ours that works. */ 2939 for (elt = elt->first_same_value; elt; elt = elt->next_same_value) 2940 if (elt->cost < our_cost 2941 && (GET_CODE (elt->exp) == REG 2942 || exp_equiv_p (elt->exp, elt->exp, 1, 0)) 2943 && validate_change (insn, loc, 2944 canon_reg (copy_rtx (elt->exp), NULL_RTX), 0)) 2945 return; 2946 } 2947#else 2948 2949 if (elt) 2950 { 2951 /* We need to find the best (under the criteria documented above) entry 2952 in the class that is valid. We use the `flag' field to indicate 2953 choices that were invalid and iterate until we can't find a better 2954 one that hasn't already been tried. */ 2955 2956 for (p = elt->first_same_value; p; p = p->next_same_value) 2957 p->flag = 0; 2958 2959 while (found_better) 2960 { 2961 int best_addr_cost = address_cost (*loc, mode); 2962 int best_rtx_cost = (elt->cost + 1) >> 1; 2963 int exp_cost; 2964 struct table_elt *best_elt = elt; 2965 2966 found_better = 0; 2967 for (p = elt->first_same_value; p; p = p->next_same_value) 2968 if (! p->flag) 2969 { 2970 if ((GET_CODE (p->exp) == REG 2971 || exp_equiv_p (p->exp, p->exp, 1, 0)) 2972 && ((exp_cost = address_cost (p->exp, mode)) < best_addr_cost 2973 || (exp_cost == best_addr_cost 2974 && ((p->cost + 1) >> 1) > best_rtx_cost))) 2975 { 2976 found_better = 1; 2977 best_addr_cost = exp_cost; 2978 best_rtx_cost = (p->cost + 1) >> 1; 2979 best_elt = p; 2980 } 2981 } 2982 2983 if (found_better) 2984 { 2985 if (validate_change (insn, loc, 2986 canon_reg (copy_rtx (best_elt->exp), 2987 NULL_RTX), 0)) 2988 return; 2989 else 2990 best_elt->flag = 1; 2991 } 2992 } 2993 } 2994 2995 /* If the address is a binary operation with the first operand a register 2996 and the second a constant, do the same as above, but looking for 2997 equivalences of the register. Then try to simplify before checking for 2998 the best address to use. This catches a few cases: First is when we 2999 have REG+const and the register is another REG+const. We can often merge 3000 the constants and eliminate one insn and one register. It may also be 3001 that a machine has a cheap REG+REG+const. Finally, this improves the 3002 code on the Alpha for unaligned byte stores. */ 3003 3004 if (flag_expensive_optimizations 3005 && (GET_RTX_CLASS (GET_CODE (*loc)) == '2' 3006 || GET_RTX_CLASS (GET_CODE (*loc)) == 'c') 3007 && GET_CODE (XEXP (*loc, 0)) == REG 3008 && GET_CODE (XEXP (*loc, 1)) == CONST_INT) 3009 { 3010 rtx c = XEXP (*loc, 1); 3011 3012 do_not_record = 0; 3013 hash = HASH (XEXP (*loc, 0), Pmode); 3014 do_not_record = save_do_not_record; 3015 hash_arg_in_memory = save_hash_arg_in_memory; 3016 3017 elt = lookup (XEXP (*loc, 0), hash, Pmode); 3018 if (elt == 0) 3019 return; 3020 3021 /* We need to find the best (under the criteria documented above) entry 3022 in the class that is valid. We use the `flag' field to indicate 3023 choices that were invalid and iterate until we can't find a better 3024 one that hasn't already been tried. */ 3025 3026 for (p = elt->first_same_value; p; p = p->next_same_value) 3027 p->flag = 0; 3028 3029 while (found_better) 3030 { 3031 int best_addr_cost = address_cost (*loc, mode); 3032 int best_rtx_cost = (COST (*loc) + 1) >> 1; 3033 struct table_elt *best_elt = elt; 3034 rtx best_rtx = *loc; 3035 int count; 3036 3037 /* This is at worst case an O(n^2) algorithm, so limit our search 3038 to the first 32 elements on the list. This avoids trouble 3039 compiling code with very long basic blocks that can easily 3040 call simplify_gen_binary so many times that we run out of 3041 memory. */ 3042 3043 found_better = 0; 3044 for (p = elt->first_same_value, count = 0; 3045 p && count < 32; 3046 p = p->next_same_value, count++) 3047 if (! p->flag 3048 && (GET_CODE (p->exp) == REG 3049 || exp_equiv_p (p->exp, p->exp, 1, 0))) 3050 { 3051 rtx new = simplify_gen_binary (GET_CODE (*loc), Pmode, 3052 p->exp, c); 3053 int new_cost; 3054 new_cost = address_cost (new, mode); 3055 3056 if (new_cost < best_addr_cost 3057 || (new_cost == best_addr_cost 3058 && (COST (new) + 1) >> 1 > best_rtx_cost)) 3059 { 3060 found_better = 1; 3061 best_addr_cost = new_cost; 3062 best_rtx_cost = (COST (new) + 1) >> 1; 3063 best_elt = p; 3064 best_rtx = new; 3065 } 3066 } 3067 3068 if (found_better) 3069 { 3070 if (validate_change (insn, loc, 3071 canon_reg (copy_rtx (best_rtx), 3072 NULL_RTX), 0)) 3073 return; 3074 else 3075 best_elt->flag = 1; 3076 } 3077 } 3078 } 3079#endif 3080} 3081 3082/* Given an operation (CODE, *PARG1, *PARG2), where code is a comparison 3083 operation (EQ, NE, GT, etc.), follow it back through the hash table and 3084 what values are being compared. 3085 3086 *PARG1 and *PARG2 are updated to contain the rtx representing the values 3087 actually being compared. For example, if *PARG1 was (cc0) and *PARG2 3088 was (const_int 0), *PARG1 and *PARG2 will be set to the objects that were 3089 compared to produce cc0. 3090 3091 The return value is the comparison operator and is either the code of 3092 A or the code corresponding to the inverse of the comparison. */ 3093 3094static enum rtx_code 3095find_comparison_args (code, parg1, parg2, pmode1, pmode2) 3096 enum rtx_code code; 3097 rtx *parg1, *parg2; 3098 enum machine_mode *pmode1, *pmode2; 3099{ 3100 rtx arg1, arg2; 3101 3102 arg1 = *parg1, arg2 = *parg2; 3103 3104 /* If ARG2 is const0_rtx, see what ARG1 is equivalent to. */ 3105 3106 while (arg2 == CONST0_RTX (GET_MODE (arg1))) 3107 { 3108 /* Set non-zero when we find something of interest. */ 3109 rtx x = 0; 3110 int reverse_code = 0; 3111 struct table_elt *p = 0; 3112 3113 /* If arg1 is a COMPARE, extract the comparison arguments from it. 3114 On machines with CC0, this is the only case that can occur, since 3115 fold_rtx will return the COMPARE or item being compared with zero 3116 when given CC0. */ 3117 3118 if (GET_CODE (arg1) == COMPARE && arg2 == const0_rtx) 3119 x = arg1; 3120 3121 /* If ARG1 is a comparison operator and CODE is testing for 3122 STORE_FLAG_VALUE, get the inner arguments. */ 3123 3124 else if (GET_RTX_CLASS (GET_CODE (arg1)) == '<') 3125 { 3126 if (code == NE 3127 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_INT 3128 && code == LT && STORE_FLAG_VALUE == -1) 3129#ifdef FLOAT_STORE_FLAG_VALUE 3130 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_FLOAT 3131 && (REAL_VALUE_NEGATIVE 3132 (FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1))))) 3133#endif 3134 ) 3135 x = arg1; 3136 else if (code == EQ 3137 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_INT 3138 && code == GE && STORE_FLAG_VALUE == -1) 3139#ifdef FLOAT_STORE_FLAG_VALUE 3140 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_FLOAT 3141 && (REAL_VALUE_NEGATIVE 3142 (FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1))))) 3143#endif 3144 ) 3145 x = arg1, reverse_code = 1; 3146 } 3147 3148 /* ??? We could also check for 3149 3150 (ne (and (eq (...) (const_int 1))) (const_int 0)) 3151 3152 and related forms, but let's wait until we see them occurring. */ 3153 3154 if (x == 0) 3155 /* Look up ARG1 in the hash table and see if it has an equivalence 3156 that lets us see what is being compared. */ 3157 p = lookup (arg1, safe_hash (arg1, GET_MODE (arg1)) & HASH_MASK, 3158 GET_MODE (arg1)); 3159 if (p) 3160 { 3161 p = p->first_same_value; 3162 3163 /* If what we compare is already known to be constant, that is as 3164 good as it gets. 3165 We need to break the loop in this case, because otherwise we 3166 can have an infinite loop when looking at a reg that is known 3167 to be a constant which is the same as a comparison of a reg 3168 against zero which appears later in the insn stream, which in 3169 turn is constant and the same as the comparison of the first reg 3170 against zero... */ 3171 if (p->is_const) 3172 break; 3173 } 3174 3175 for (; p; p = p->next_same_value) 3176 { 3177 enum machine_mode inner_mode = GET_MODE (p->exp); 3178 3179 /* If the entry isn't valid, skip it. */ 3180 if (! exp_equiv_p (p->exp, p->exp, 1, 0)) 3181 continue; 3182 3183 if (GET_CODE (p->exp) == COMPARE 3184 /* Another possibility is that this machine has a compare insn 3185 that includes the comparison code. In that case, ARG1 would 3186 be equivalent to a comparison operation that would set ARG1 to 3187 either STORE_FLAG_VALUE or zero. If this is an NE operation, 3188 ORIG_CODE is the actual comparison being done; if it is an EQ, 3189 we must reverse ORIG_CODE. On machine with a negative value 3190 for STORE_FLAG_VALUE, also look at LT and GE operations. */ 3191 || ((code == NE 3192 || (code == LT 3193 && GET_MODE_CLASS (inner_mode) == MODE_INT 3194 && (GET_MODE_BITSIZE (inner_mode) 3195 <= HOST_BITS_PER_WIDE_INT) 3196 && (STORE_FLAG_VALUE 3197 & ((HOST_WIDE_INT) 1 3198 << (GET_MODE_BITSIZE (inner_mode) - 1)))) 3199#ifdef FLOAT_STORE_FLAG_VALUE 3200 || (code == LT 3201 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT 3202 && (REAL_VALUE_NEGATIVE 3203 (FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1))))) 3204#endif 3205 ) 3206 && GET_RTX_CLASS (GET_CODE (p->exp)) == '<')) 3207 { 3208 x = p->exp; 3209 break; 3210 } 3211 else if ((code == EQ 3212 || (code == GE 3213 && GET_MODE_CLASS (inner_mode) == MODE_INT 3214 && (GET_MODE_BITSIZE (inner_mode) 3215 <= HOST_BITS_PER_WIDE_INT) 3216 && (STORE_FLAG_VALUE 3217 & ((HOST_WIDE_INT) 1 3218 << (GET_MODE_BITSIZE (inner_mode) - 1)))) 3219#ifdef FLOAT_STORE_FLAG_VALUE 3220 || (code == GE 3221 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT 3222 && (REAL_VALUE_NEGATIVE 3223 (FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1))))) 3224#endif 3225 ) 3226 && GET_RTX_CLASS (GET_CODE (p->exp)) == '<') 3227 { 3228 reverse_code = 1; 3229 x = p->exp; 3230 break; 3231 } 3232 3233 /* If this is fp + constant, the equivalent is a better operand since 3234 it may let us predict the value of the comparison. */ 3235 else if (NONZERO_BASE_PLUS_P (p->exp)) 3236 { 3237 arg1 = p->exp; 3238 continue; 3239 } 3240 } 3241 3242 /* If we didn't find a useful equivalence for ARG1, we are done. 3243 Otherwise, set up for the next iteration. */ 3244 if (x == 0) 3245 break; 3246 3247 /* If we need to reverse the comparison, make sure that that is 3248 possible -- we can't necessarily infer the value of GE from LT 3249 with floating-point operands. */ 3250 if (reverse_code) 3251 { 3252 enum rtx_code reversed = reversed_comparison_code (x, NULL_RTX); 3253 if (reversed == UNKNOWN) 3254 break; 3255 else code = reversed; 3256 } 3257 else if (GET_RTX_CLASS (GET_CODE (x)) == '<') 3258 code = GET_CODE (x); 3259 arg1 = XEXP (x, 0), arg2 = XEXP (x, 1); 3260 } 3261 3262 /* Return our results. Return the modes from before fold_rtx 3263 because fold_rtx might produce const_int, and then it's too late. */ 3264 *pmode1 = GET_MODE (arg1), *pmode2 = GET_MODE (arg2); 3265 *parg1 = fold_rtx (arg1, 0), *parg2 = fold_rtx (arg2, 0); 3266 3267 return code; 3268} 3269 3270/* If X is a nontrivial arithmetic operation on an argument 3271 for which a constant value can be determined, return 3272 the result of operating on that value, as a constant. 3273 Otherwise, return X, possibly with one or more operands 3274 modified by recursive calls to this function. 3275 3276 If X is a register whose contents are known, we do NOT 3277 return those contents here. equiv_constant is called to 3278 perform that task. 3279 3280 INSN is the insn that we may be modifying. If it is 0, make a copy 3281 of X before modifying it. */ 3282 3283static rtx 3284fold_rtx (x, insn) 3285 rtx x; 3286 rtx insn; 3287{ 3288 enum rtx_code code; 3289 enum machine_mode mode; 3290 const char *fmt; 3291 int i; 3292 rtx new = 0; 3293 int copied = 0; 3294 int must_swap = 0; 3295 3296 /* Folded equivalents of first two operands of X. */ 3297 rtx folded_arg0; 3298 rtx folded_arg1; 3299 3300 /* Constant equivalents of first three operands of X; 3301 0 when no such equivalent is known. */ 3302 rtx const_arg0; 3303 rtx const_arg1; 3304 rtx const_arg2; 3305 3306 /* The mode of the first operand of X. We need this for sign and zero 3307 extends. */ 3308 enum machine_mode mode_arg0; 3309 3310 if (x == 0) 3311 return x; 3312 3313 mode = GET_MODE (x); 3314 code = GET_CODE (x); 3315 switch (code) 3316 { 3317 case CONST: 3318 case CONST_INT: 3319 case CONST_DOUBLE: 3320 case SYMBOL_REF: 3321 case LABEL_REF: 3322 case REG: 3323 /* No use simplifying an EXPR_LIST 3324 since they are used only for lists of args 3325 in a function call's REG_EQUAL note. */ 3326 case EXPR_LIST: 3327 /* Changing anything inside an ADDRESSOF is incorrect; we don't 3328 want to (e.g.,) make (addressof (const_int 0)) just because 3329 the location is known to be zero. */ 3330 case ADDRESSOF: 3331 return x; 3332 3333#ifdef HAVE_cc0 3334 case CC0: 3335 return prev_insn_cc0; 3336#endif 3337 3338 case PC: 3339 /* If the next insn is a CODE_LABEL followed by a jump table, 3340 PC's value is a LABEL_REF pointing to that label. That 3341 lets us fold switch statements on the VAX. */ 3342 if (insn && GET_CODE (insn) == JUMP_INSN) 3343 { 3344 rtx next = next_nonnote_insn (insn); 3345 3346 if (next && GET_CODE (next) == CODE_LABEL 3347 && NEXT_INSN (next) != 0 3348 && GET_CODE (NEXT_INSN (next)) == JUMP_INSN 3349 && (GET_CODE (PATTERN (NEXT_INSN (next))) == ADDR_VEC 3350 || GET_CODE (PATTERN (NEXT_INSN (next))) == ADDR_DIFF_VEC)) 3351 return gen_rtx_LABEL_REF (Pmode, next); 3352 } 3353 break; 3354 3355 case SUBREG: 3356 /* See if we previously assigned a constant value to this SUBREG. */ 3357 if ((new = lookup_as_function (x, CONST_INT)) != 0 3358 || (new = lookup_as_function (x, CONST_DOUBLE)) != 0) 3359 return new; 3360 3361 /* If this is a paradoxical SUBREG, we have no idea what value the 3362 extra bits would have. However, if the operand is equivalent 3363 to a SUBREG whose operand is the same as our mode, and all the 3364 modes are within a word, we can just use the inner operand 3365 because these SUBREGs just say how to treat the register. 3366 3367 Similarly if we find an integer constant. */ 3368 3369 if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) 3370 { 3371 enum machine_mode imode = GET_MODE (SUBREG_REG (x)); 3372 struct table_elt *elt; 3373 3374 if (GET_MODE_SIZE (mode) <= UNITS_PER_WORD 3375 && GET_MODE_SIZE (imode) <= UNITS_PER_WORD 3376 && (elt = lookup (SUBREG_REG (x), HASH (SUBREG_REG (x), imode), 3377 imode)) != 0) 3378 for (elt = elt->first_same_value; elt; elt = elt->next_same_value) 3379 { 3380 if (CONSTANT_P (elt->exp) 3381 && GET_MODE (elt->exp) == VOIDmode) 3382 return elt->exp; 3383 3384 if (GET_CODE (elt->exp) == SUBREG 3385 && GET_MODE (SUBREG_REG (elt->exp)) == mode 3386 && exp_equiv_p (elt->exp, elt->exp, 1, 0)) 3387 return copy_rtx (SUBREG_REG (elt->exp)); 3388 } 3389 3390 return x; 3391 } 3392 3393 /* Fold SUBREG_REG. If it changed, see if we can simplify the SUBREG. 3394 We might be able to if the SUBREG is extracting a single word in an 3395 integral mode or extracting the low part. */ 3396 3397 folded_arg0 = fold_rtx (SUBREG_REG (x), insn); 3398 const_arg0 = equiv_constant (folded_arg0); 3399 if (const_arg0) 3400 folded_arg0 = const_arg0; 3401 3402 if (folded_arg0 != SUBREG_REG (x)) 3403 { 3404 new = simplify_subreg (mode, folded_arg0, 3405 GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x)); 3406 if (new) 3407 return new; 3408 } 3409 3410 /* If this is a narrowing SUBREG and our operand is a REG, see if 3411 we can find an equivalence for REG that is an arithmetic operation 3412 in a wider mode where both operands are paradoxical SUBREGs 3413 from objects of our result mode. In that case, we couldn't report 3414 an equivalent value for that operation, since we don't know what the 3415 extra bits will be. But we can find an equivalence for this SUBREG 3416 by folding that operation is the narrow mode. This allows us to 3417 fold arithmetic in narrow modes when the machine only supports 3418 word-sized arithmetic. 3419 3420 Also look for a case where we have a SUBREG whose operand is the 3421 same as our result. If both modes are smaller than a word, we 3422 are simply interpreting a register in different modes and we 3423 can use the inner value. */ 3424 3425 if (GET_CODE (folded_arg0) == REG 3426 && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (folded_arg0)) 3427 && subreg_lowpart_p (x)) 3428 { 3429 struct table_elt *elt; 3430 3431 /* We can use HASH here since we know that canon_hash won't be 3432 called. */ 3433 elt = lookup (folded_arg0, 3434 HASH (folded_arg0, GET_MODE (folded_arg0)), 3435 GET_MODE (folded_arg0)); 3436 3437 if (elt) 3438 elt = elt->first_same_value; 3439 3440 for (; elt; elt = elt->next_same_value) 3441 { 3442 enum rtx_code eltcode = GET_CODE (elt->exp); 3443 3444 /* Just check for unary and binary operations. */ 3445 if (GET_RTX_CLASS (GET_CODE (elt->exp)) == '1' 3446 && GET_CODE (elt->exp) != SIGN_EXTEND 3447 && GET_CODE (elt->exp) != ZERO_EXTEND 3448 && GET_CODE (XEXP (elt->exp, 0)) == SUBREG 3449 && GET_MODE (SUBREG_REG (XEXP (elt->exp, 0))) == mode) 3450 { 3451 rtx op0 = SUBREG_REG (XEXP (elt->exp, 0)); 3452 3453 if (GET_CODE (op0) != REG && ! CONSTANT_P (op0)) 3454 op0 = fold_rtx (op0, NULL_RTX); 3455 3456 op0 = equiv_constant (op0); 3457 if (op0) 3458 new = simplify_unary_operation (GET_CODE (elt->exp), mode, 3459 op0, mode); 3460 } 3461 else if ((GET_RTX_CLASS (GET_CODE (elt->exp)) == '2' 3462 || GET_RTX_CLASS (GET_CODE (elt->exp)) == 'c') 3463 && eltcode != DIV && eltcode != MOD 3464 && eltcode != UDIV && eltcode != UMOD 3465 && eltcode != ASHIFTRT && eltcode != LSHIFTRT 3466 && eltcode != ROTATE && eltcode != ROTATERT 3467 && ((GET_CODE (XEXP (elt->exp, 0)) == SUBREG 3468 && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 0))) 3469 == mode)) 3470 || CONSTANT_P (XEXP (elt->exp, 0))) 3471 && ((GET_CODE (XEXP (elt->exp, 1)) == SUBREG 3472 && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 1))) 3473 == mode)) 3474 || CONSTANT_P (XEXP (elt->exp, 1)))) 3475 { 3476 rtx op0 = gen_lowpart_common (mode, XEXP (elt->exp, 0)); 3477 rtx op1 = gen_lowpart_common (mode, XEXP (elt->exp, 1)); 3478 3479 if (op0 && GET_CODE (op0) != REG && ! CONSTANT_P (op0)) 3480 op0 = fold_rtx (op0, NULL_RTX); 3481 3482 if (op0) 3483 op0 = equiv_constant (op0); 3484 3485 if (op1 && GET_CODE (op1) != REG && ! CONSTANT_P (op1)) 3486 op1 = fold_rtx (op1, NULL_RTX); 3487 3488 if (op1) 3489 op1 = equiv_constant (op1); 3490 3491 /* If we are looking for the low SImode part of 3492 (ashift:DI c (const_int 32)), it doesn't work 3493 to compute that in SImode, because a 32-bit shift 3494 in SImode is unpredictable. We know the value is 0. */ 3495 if (op0 && op1 3496 && GET_CODE (elt->exp) == ASHIFT 3497 && GET_CODE (op1) == CONST_INT 3498 && INTVAL (op1) >= GET_MODE_BITSIZE (mode)) 3499 { 3500 if (INTVAL (op1) < GET_MODE_BITSIZE (GET_MODE (elt->exp))) 3501 3502 /* If the count fits in the inner mode's width, 3503 but exceeds the outer mode's width, 3504 the value will get truncated to 0 3505 by the subreg. */ 3506 new = const0_rtx; 3507 else 3508 /* If the count exceeds even the inner mode's width, 3509 don't fold this expression. */ 3510 new = 0; 3511 } 3512 else if (op0 && op1) 3513 new = simplify_binary_operation (GET_CODE (elt->exp), mode, 3514 op0, op1); 3515 } 3516 3517 else if (GET_CODE (elt->exp) == SUBREG 3518 && GET_MODE (SUBREG_REG (elt->exp)) == mode 3519 && (GET_MODE_SIZE (GET_MODE (folded_arg0)) 3520 <= UNITS_PER_WORD) 3521 && exp_equiv_p (elt->exp, elt->exp, 1, 0)) 3522 new = copy_rtx (SUBREG_REG (elt->exp)); 3523 3524 if (new) 3525 return new; 3526 } 3527 } 3528 3529 return x; 3530 3531 case NOT: 3532 case NEG: 3533 /* If we have (NOT Y), see if Y is known to be (NOT Z). 3534 If so, (NOT Y) simplifies to Z. Similarly for NEG. */ 3535 new = lookup_as_function (XEXP (x, 0), code); 3536 if (new) 3537 return fold_rtx (copy_rtx (XEXP (new, 0)), insn); 3538 break; 3539 3540 case MEM: 3541 /* If we are not actually processing an insn, don't try to find the 3542 best address. Not only don't we care, but we could modify the 3543 MEM in an invalid way since we have no insn to validate against. */ 3544 if (insn != 0) 3545 find_best_addr (insn, &XEXP (x, 0), GET_MODE (x)); 3546 3547 { 3548 /* Even if we don't fold in the insn itself, 3549 we can safely do so here, in hopes of getting a constant. */ 3550 rtx addr = fold_rtx (XEXP (x, 0), NULL_RTX); 3551 rtx base = 0; 3552 HOST_WIDE_INT offset = 0; 3553 3554 if (GET_CODE (addr) == REG 3555 && REGNO_QTY_VALID_P (REGNO (addr))) 3556 { 3557 int addr_q = REG_QTY (REGNO (addr)); 3558 struct qty_table_elem *addr_ent = &qty_table[addr_q]; 3559 3560 if (GET_MODE (addr) == addr_ent->mode 3561 && addr_ent->const_rtx != NULL_RTX) 3562 addr = addr_ent->const_rtx; 3563 } 3564 3565 /* If address is constant, split it into a base and integer offset. */ 3566 if (GET_CODE (addr) == SYMBOL_REF || GET_CODE (addr) == LABEL_REF) 3567 base = addr; 3568 else if (GET_CODE (addr) == CONST && GET_CODE (XEXP (addr, 0)) == PLUS 3569 && GET_CODE (XEXP (XEXP (addr, 0), 1)) == CONST_INT) 3570 { 3571 base = XEXP (XEXP (addr, 0), 0); 3572 offset = INTVAL (XEXP (XEXP (addr, 0), 1)); 3573 } 3574 else if (GET_CODE (addr) == LO_SUM 3575 && GET_CODE (XEXP (addr, 1)) == SYMBOL_REF) 3576 base = XEXP (addr, 1); 3577 else if (GET_CODE (addr) == ADDRESSOF) 3578 return change_address (x, VOIDmode, addr); 3579 3580 /* If this is a constant pool reference, we can fold it into its 3581 constant to allow better value tracking. */ 3582 if (base && GET_CODE (base) == SYMBOL_REF 3583 && CONSTANT_POOL_ADDRESS_P (base)) 3584 { 3585 rtx constant = get_pool_constant (base); 3586 enum machine_mode const_mode = get_pool_mode (base); 3587 rtx new; 3588 3589 if (CONSTANT_P (constant) && GET_CODE (constant) != CONST_INT) 3590 constant_pool_entries_cost = COST (constant); 3591 3592 /* If we are loading the full constant, we have an equivalence. */ 3593 if (offset == 0 && mode == const_mode) 3594 return constant; 3595 3596 /* If this actually isn't a constant (weird!), we can't do 3597 anything. Otherwise, handle the two most common cases: 3598 extracting a word from a multi-word constant, and extracting 3599 the low-order bits. Other cases don't seem common enough to 3600 worry about. */ 3601 if (! CONSTANT_P (constant)) 3602 return x; 3603 3604 if (GET_MODE_CLASS (mode) == MODE_INT 3605 && GET_MODE_SIZE (mode) == UNITS_PER_WORD 3606 && offset % UNITS_PER_WORD == 0 3607 && (new = operand_subword (constant, 3608 offset / UNITS_PER_WORD, 3609 0, const_mode)) != 0) 3610 return new; 3611 3612 if (((BYTES_BIG_ENDIAN 3613 && offset == GET_MODE_SIZE (GET_MODE (constant)) - 1) 3614 || (! BYTES_BIG_ENDIAN && offset == 0)) 3615 && (new = gen_lowpart_if_possible (mode, constant)) != 0) 3616 return new; 3617 } 3618 3619 /* If this is a reference to a label at a known position in a jump 3620 table, we also know its value. */ 3621 if (base && GET_CODE (base) == LABEL_REF) 3622 { 3623 rtx label = XEXP (base, 0); 3624 rtx table_insn = NEXT_INSN (label); 3625 3626 if (table_insn && GET_CODE (table_insn) == JUMP_INSN 3627 && GET_CODE (PATTERN (table_insn)) == ADDR_VEC) 3628 { 3629 rtx table = PATTERN (table_insn); 3630 3631 if (offset >= 0 3632 && (offset / GET_MODE_SIZE (GET_MODE (table)) 3633 < XVECLEN (table, 0))) 3634 return XVECEXP (table, 0, 3635 offset / GET_MODE_SIZE (GET_MODE (table))); 3636 } 3637 if (table_insn && GET_CODE (table_insn) == JUMP_INSN 3638 && GET_CODE (PATTERN (table_insn)) == ADDR_DIFF_VEC) 3639 { 3640 rtx table = PATTERN (table_insn); 3641 3642 if (offset >= 0 3643 && (offset / GET_MODE_SIZE (GET_MODE (table)) 3644 < XVECLEN (table, 1))) 3645 { 3646 offset /= GET_MODE_SIZE (GET_MODE (table)); 3647 new = gen_rtx_MINUS (Pmode, XVECEXP (table, 1, offset), 3648 XEXP (table, 0)); 3649 3650 if (GET_MODE (table) != Pmode) 3651 new = gen_rtx_TRUNCATE (GET_MODE (table), new); 3652 3653 /* Indicate this is a constant. This isn't a 3654 valid form of CONST, but it will only be used 3655 to fold the next insns and then discarded, so 3656 it should be safe. 3657 3658 Note this expression must be explicitly discarded, 3659 by cse_insn, else it may end up in a REG_EQUAL note 3660 and "escape" to cause problems elsewhere. */ 3661 return gen_rtx_CONST (GET_MODE (new), new); 3662 } 3663 } 3664 } 3665 3666 return x; 3667 } 3668 3669#ifdef NO_FUNCTION_CSE 3670 case CALL: 3671 if (CONSTANT_P (XEXP (XEXP (x, 0), 0))) 3672 return x; 3673 break; 3674#endif 3675 3676 case ASM_OPERANDS: 3677 for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--) 3678 validate_change (insn, &ASM_OPERANDS_INPUT (x, i), 3679 fold_rtx (ASM_OPERANDS_INPUT (x, i), insn), 0); 3680 break; 3681 3682 default: 3683 break; 3684 } 3685 3686 const_arg0 = 0; 3687 const_arg1 = 0; 3688 const_arg2 = 0; 3689 mode_arg0 = VOIDmode; 3690 3691 /* Try folding our operands. 3692 Then see which ones have constant values known. */ 3693 3694 fmt = GET_RTX_FORMAT (code); 3695 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 3696 if (fmt[i] == 'e') 3697 { 3698 rtx arg = XEXP (x, i); 3699 rtx folded_arg = arg, const_arg = 0; 3700 enum machine_mode mode_arg = GET_MODE (arg); 3701 rtx cheap_arg, expensive_arg; 3702 rtx replacements[2]; 3703 int j; 3704 3705 /* Most arguments are cheap, so handle them specially. */ 3706 switch (GET_CODE (arg)) 3707 { 3708 case REG: 3709 /* This is the same as calling equiv_constant; it is duplicated 3710 here for speed. */ 3711 if (REGNO_QTY_VALID_P (REGNO (arg))) 3712 { 3713 int arg_q = REG_QTY (REGNO (arg)); 3714 struct qty_table_elem *arg_ent = &qty_table[arg_q]; 3715 3716 if (arg_ent->const_rtx != NULL_RTX 3717 && GET_CODE (arg_ent->const_rtx) != REG 3718 && GET_CODE (arg_ent->const_rtx) != PLUS) 3719 const_arg 3720 = gen_lowpart_if_possible (GET_MODE (arg), 3721 arg_ent->const_rtx); 3722 } 3723 break; 3724 3725 case CONST: 3726 case CONST_INT: 3727 case SYMBOL_REF: 3728 case LABEL_REF: 3729 case CONST_DOUBLE: 3730 const_arg = arg; 3731 break; 3732 3733#ifdef HAVE_cc0 3734 case CC0: 3735 folded_arg = prev_insn_cc0; 3736 mode_arg = prev_insn_cc0_mode; 3737 const_arg = equiv_constant (folded_arg); 3738 break; 3739#endif 3740 3741 default: 3742 folded_arg = fold_rtx (arg, insn); 3743 const_arg = equiv_constant (folded_arg); 3744 } 3745 3746 /* For the first three operands, see if the operand 3747 is constant or equivalent to a constant. */ 3748 switch (i) 3749 { 3750 case 0: 3751 folded_arg0 = folded_arg; 3752 const_arg0 = const_arg; 3753 mode_arg0 = mode_arg; 3754 break; 3755 case 1: 3756 folded_arg1 = folded_arg; 3757 const_arg1 = const_arg; 3758 break; 3759 case 2: 3760 const_arg2 = const_arg; 3761 break; 3762 } 3763 3764 /* Pick the least expensive of the folded argument and an 3765 equivalent constant argument. */ 3766 if (const_arg == 0 || const_arg == folded_arg 3767 || COST_IN (const_arg, code) > COST_IN (folded_arg, code)) 3768 cheap_arg = folded_arg, expensive_arg = const_arg; 3769 else 3770 cheap_arg = const_arg, expensive_arg = folded_arg; 3771 3772 /* Try to replace the operand with the cheapest of the two 3773 possibilities. If it doesn't work and this is either of the first 3774 two operands of a commutative operation, try swapping them. 3775 If THAT fails, try the more expensive, provided it is cheaper 3776 than what is already there. */ 3777 3778 if (cheap_arg == XEXP (x, i)) 3779 continue; 3780 3781 if (insn == 0 && ! copied) 3782 { 3783 x = copy_rtx (x); 3784 copied = 1; 3785 } 3786 3787 /* Order the replacements from cheapest to most expensive. */ 3788 replacements[0] = cheap_arg; 3789 replacements[1] = expensive_arg; 3790 3791 for (j = 0; j < 2 && replacements[j]; j++) 3792 { 3793 int old_cost = COST_IN (XEXP (x, i), code); 3794 int new_cost = COST_IN (replacements[j], code); 3795 3796 /* Stop if what existed before was cheaper. Prefer constants 3797 in the case of a tie. */ 3798 if (new_cost > old_cost 3799 || (new_cost == old_cost && CONSTANT_P (XEXP (x, i)))) 3800 break; 3801 3802 if (validate_change (insn, &XEXP (x, i), replacements[j], 0)) 3803 break; 3804 3805 if (code == NE || code == EQ || GET_RTX_CLASS (code) == 'c' 3806 || code == LTGT || code == UNEQ || code == ORDERED 3807 || code == UNORDERED) 3808 { 3809 validate_change (insn, &XEXP (x, i), XEXP (x, 1 - i), 1); 3810 validate_change (insn, &XEXP (x, 1 - i), replacements[j], 1); 3811 3812 if (apply_change_group ()) 3813 { 3814 /* Swap them back to be invalid so that this loop can 3815 continue and flag them to be swapped back later. */ 3816 rtx tem; 3817 3818 tem = XEXP (x, 0); XEXP (x, 0) = XEXP (x, 1); 3819 XEXP (x, 1) = tem; 3820 must_swap = 1; 3821 break; 3822 } 3823 } 3824 } 3825 } 3826 3827 else 3828 { 3829 if (fmt[i] == 'E') 3830 /* Don't try to fold inside of a vector of expressions. 3831 Doing nothing is harmless. */ 3832 {;} 3833 } 3834 3835 /* If a commutative operation, place a constant integer as the second 3836 operand unless the first operand is also a constant integer. Otherwise, 3837 place any constant second unless the first operand is also a constant. */ 3838 3839 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c' 3840 || code == LTGT || code == UNEQ || code == ORDERED 3841 || code == UNORDERED) 3842 { 3843 if (must_swap || (const_arg0 3844 && (const_arg1 == 0 3845 || (GET_CODE (const_arg0) == CONST_INT 3846 && GET_CODE (const_arg1) != CONST_INT)))) 3847 { 3848 rtx tem = XEXP (x, 0); 3849 3850 if (insn == 0 && ! copied) 3851 { 3852 x = copy_rtx (x); 3853 copied = 1; 3854 } 3855 3856 validate_change (insn, &XEXP (x, 0), XEXP (x, 1), 1); 3857 validate_change (insn, &XEXP (x, 1), tem, 1); 3858 if (apply_change_group ()) 3859 { 3860 tem = const_arg0, const_arg0 = const_arg1, const_arg1 = tem; 3861 tem = folded_arg0, folded_arg0 = folded_arg1, folded_arg1 = tem; 3862 } 3863 } 3864 } 3865 3866 /* If X is an arithmetic operation, see if we can simplify it. */ 3867 3868 switch (GET_RTX_CLASS (code)) 3869 { 3870 case '1': 3871 { 3872 int is_const = 0; 3873 3874 /* We can't simplify extension ops unless we know the 3875 original mode. */ 3876 if ((code == ZERO_EXTEND || code == SIGN_EXTEND) 3877 && mode_arg0 == VOIDmode) 3878 break; 3879 3880 /* If we had a CONST, strip it off and put it back later if we 3881 fold. */ 3882 if (const_arg0 != 0 && GET_CODE (const_arg0) == CONST) 3883 is_const = 1, const_arg0 = XEXP (const_arg0, 0); 3884 3885 new = simplify_unary_operation (code, mode, 3886 const_arg0 ? const_arg0 : folded_arg0, 3887 mode_arg0); 3888 if (new != 0 && is_const) 3889 new = gen_rtx_CONST (mode, new); 3890 } 3891 break; 3892 3893 case '<': 3894 /* See what items are actually being compared and set FOLDED_ARG[01] 3895 to those values and CODE to the actual comparison code. If any are 3896 constant, set CONST_ARG0 and CONST_ARG1 appropriately. We needn't 3897 do anything if both operands are already known to be constant. */ 3898 3899 if (const_arg0 == 0 || const_arg1 == 0) 3900 { 3901 struct table_elt *p0, *p1; 3902 rtx true_rtx = const_true_rtx, false_rtx = const0_rtx; 3903 enum machine_mode mode_arg1; 3904 3905#ifdef FLOAT_STORE_FLAG_VALUE 3906 if (GET_MODE_CLASS (mode) == MODE_FLOAT) 3907 { 3908 true_rtx = (CONST_DOUBLE_FROM_REAL_VALUE 3909 (FLOAT_STORE_FLAG_VALUE (mode), mode)); 3910 false_rtx = CONST0_RTX (mode); 3911 } 3912#endif 3913 3914 code = find_comparison_args (code, &folded_arg0, &folded_arg1, 3915 &mode_arg0, &mode_arg1); 3916 const_arg0 = equiv_constant (folded_arg0); 3917 const_arg1 = equiv_constant (folded_arg1); 3918 3919 /* If the mode is VOIDmode or a MODE_CC mode, we don't know 3920 what kinds of things are being compared, so we can't do 3921 anything with this comparison. */ 3922 3923 if (mode_arg0 == VOIDmode || GET_MODE_CLASS (mode_arg0) == MODE_CC) 3924 break; 3925 3926 /* If we do not now have two constants being compared, see 3927 if we can nevertheless deduce some things about the 3928 comparison. */ 3929 if (const_arg0 == 0 || const_arg1 == 0) 3930 { 3931 /* Is FOLDED_ARG0 frame-pointer plus a constant? Or 3932 non-explicit constant? These aren't zero, but we 3933 don't know their sign. */ 3934 if (const_arg1 == const0_rtx 3935 && (NONZERO_BASE_PLUS_P (folded_arg0) 3936#if 0 /* Sad to say, on sysvr4, #pragma weak can make a symbol address 3937 come out as 0. */ 3938 || GET_CODE (folded_arg0) == SYMBOL_REF 3939#endif 3940 || GET_CODE (folded_arg0) == LABEL_REF 3941 || GET_CODE (folded_arg0) == CONST)) 3942 { 3943 if (code == EQ) 3944 return false_rtx; 3945 else if (code == NE) 3946 return true_rtx; 3947 } 3948 3949 /* See if the two operands are the same. */ 3950 3951 if (folded_arg0 == folded_arg1 3952 || (GET_CODE (folded_arg0) == REG 3953 && GET_CODE (folded_arg1) == REG 3954 && (REG_QTY (REGNO (folded_arg0)) 3955 == REG_QTY (REGNO (folded_arg1)))) 3956 || ((p0 = lookup (folded_arg0, 3957 (safe_hash (folded_arg0, mode_arg0) 3958 & HASH_MASK), mode_arg0)) 3959 && (p1 = lookup (folded_arg1, 3960 (safe_hash (folded_arg1, mode_arg0) 3961 & HASH_MASK), mode_arg0)) 3962 && p0->first_same_value == p1->first_same_value)) 3963 { 3964 /* Sadly two equal NaNs are not equivalent. */ 3965 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT 3966 || ! FLOAT_MODE_P (mode_arg0) 3967 || flag_unsafe_math_optimizations) 3968 return ((code == EQ || code == LE || code == GE 3969 || code == LEU || code == GEU || code == UNEQ 3970 || code == UNLE || code == UNGE || code == ORDERED) 3971 ? true_rtx : false_rtx); 3972 /* Take care for the FP compares we can resolve. */ 3973 if (code == UNEQ || code == UNLE || code == UNGE) 3974 return true_rtx; 3975 if (code == LTGT || code == LT || code == GT) 3976 return false_rtx; 3977 } 3978 3979 /* If FOLDED_ARG0 is a register, see if the comparison we are 3980 doing now is either the same as we did before or the reverse 3981 (we only check the reverse if not floating-point). */ 3982 else if (GET_CODE (folded_arg0) == REG) 3983 { 3984 int qty = REG_QTY (REGNO (folded_arg0)); 3985 3986 if (REGNO_QTY_VALID_P (REGNO (folded_arg0))) 3987 { 3988 struct qty_table_elem *ent = &qty_table[qty]; 3989 3990 if ((comparison_dominates_p (ent->comparison_code, code) 3991 || (! FLOAT_MODE_P (mode_arg0) 3992 && comparison_dominates_p (ent->comparison_code, 3993 reverse_condition (code)))) 3994 && (rtx_equal_p (ent->comparison_const, folded_arg1) 3995 || (const_arg1 3996 && rtx_equal_p (ent->comparison_const, 3997 const_arg1)) 3998 || (GET_CODE (folded_arg1) == REG 3999 && (REG_QTY (REGNO (folded_arg1)) == ent->comparison_qty)))) 4000 return (comparison_dominates_p (ent->comparison_code, code) 4001 ? true_rtx : false_rtx); 4002 } 4003 } 4004 } 4005 } 4006 4007 /* If we are comparing against zero, see if the first operand is 4008 equivalent to an IOR with a constant. If so, we may be able to 4009 determine the result of this comparison. */ 4010 4011 if (const_arg1 == const0_rtx) 4012 { 4013 rtx y = lookup_as_function (folded_arg0, IOR); 4014 rtx inner_const; 4015 4016 if (y != 0 4017 && (inner_const = equiv_constant (XEXP (y, 1))) != 0 4018 && GET_CODE (inner_const) == CONST_INT 4019 && INTVAL (inner_const) != 0) 4020 { 4021 int sign_bitnum = GET_MODE_BITSIZE (mode_arg0) - 1; 4022 int has_sign = (HOST_BITS_PER_WIDE_INT >= sign_bitnum 4023 && (INTVAL (inner_const) 4024 & ((HOST_WIDE_INT) 1 << sign_bitnum))); 4025 rtx true_rtx = const_true_rtx, false_rtx = const0_rtx; 4026 4027#ifdef FLOAT_STORE_FLAG_VALUE 4028 if (GET_MODE_CLASS (mode) == MODE_FLOAT) 4029 { 4030 true_rtx = (CONST_DOUBLE_FROM_REAL_VALUE 4031 (FLOAT_STORE_FLAG_VALUE (mode), mode)); 4032 false_rtx = CONST0_RTX (mode); 4033 } 4034#endif 4035 4036 switch (code) 4037 { 4038 case EQ: 4039 return false_rtx; 4040 case NE: 4041 return true_rtx; 4042 case LT: case LE: 4043 if (has_sign) 4044 return true_rtx; 4045 break; 4046 case GT: case GE: 4047 if (has_sign) 4048 return false_rtx; 4049 break; 4050 default: 4051 break; 4052 } 4053 } 4054 } 4055 4056 new = simplify_relational_operation (code, 4057 (mode_arg0 != VOIDmode 4058 ? mode_arg0 4059 : (GET_MODE (const_arg0 4060 ? const_arg0 4061 : folded_arg0) 4062 != VOIDmode) 4063 ? GET_MODE (const_arg0 4064 ? const_arg0 4065 : folded_arg0) 4066 : GET_MODE (const_arg1 4067 ? const_arg1 4068 : folded_arg1)), 4069 const_arg0 ? const_arg0 : folded_arg0, 4070 const_arg1 ? const_arg1 : folded_arg1); 4071#ifdef FLOAT_STORE_FLAG_VALUE 4072 if (new != 0 && GET_MODE_CLASS (mode) == MODE_FLOAT) 4073 { 4074 if (new == const0_rtx) 4075 new = CONST0_RTX (mode); 4076 else 4077 new = (CONST_DOUBLE_FROM_REAL_VALUE 4078 (FLOAT_STORE_FLAG_VALUE (mode), mode)); 4079 } 4080#endif 4081 break; 4082 4083 case '2': 4084 case 'c': 4085 switch (code) 4086 { 4087 case PLUS: 4088 /* If the second operand is a LABEL_REF, see if the first is a MINUS 4089 with that LABEL_REF as its second operand. If so, the result is 4090 the first operand of that MINUS. This handles switches with an 4091 ADDR_DIFF_VEC table. */ 4092 if (const_arg1 && GET_CODE (const_arg1) == LABEL_REF) 4093 { 4094 rtx y 4095 = GET_CODE (folded_arg0) == MINUS ? folded_arg0 4096 : lookup_as_function (folded_arg0, MINUS); 4097 4098 if (y != 0 && GET_CODE (XEXP (y, 1)) == LABEL_REF 4099 && XEXP (XEXP (y, 1), 0) == XEXP (const_arg1, 0)) 4100 return XEXP (y, 0); 4101 4102 /* Now try for a CONST of a MINUS like the above. */ 4103 if ((y = (GET_CODE (folded_arg0) == CONST ? folded_arg0 4104 : lookup_as_function (folded_arg0, CONST))) != 0 4105 && GET_CODE (XEXP (y, 0)) == MINUS 4106 && GET_CODE (XEXP (XEXP (y, 0), 1)) == LABEL_REF 4107 && XEXP (XEXP (XEXP (y, 0), 1), 0) == XEXP (const_arg1, 0)) 4108 return XEXP (XEXP (y, 0), 0); 4109 } 4110 4111 /* Likewise if the operands are in the other order. */ 4112 if (const_arg0 && GET_CODE (const_arg0) == LABEL_REF) 4113 { 4114 rtx y 4115 = GET_CODE (folded_arg1) == MINUS ? folded_arg1 4116 : lookup_as_function (folded_arg1, MINUS); 4117 4118 if (y != 0 && GET_CODE (XEXP (y, 1)) == LABEL_REF 4119 && XEXP (XEXP (y, 1), 0) == XEXP (const_arg0, 0)) 4120 return XEXP (y, 0); 4121 4122 /* Now try for a CONST of a MINUS like the above. */ 4123 if ((y = (GET_CODE (folded_arg1) == CONST ? folded_arg1 4124 : lookup_as_function (folded_arg1, CONST))) != 0 4125 && GET_CODE (XEXP (y, 0)) == MINUS 4126 && GET_CODE (XEXP (XEXP (y, 0), 1)) == LABEL_REF 4127 && XEXP (XEXP (XEXP (y, 0), 1), 0) == XEXP (const_arg0, 0)) 4128 return XEXP (XEXP (y, 0), 0); 4129 } 4130 4131 /* If second operand is a register equivalent to a negative 4132 CONST_INT, see if we can find a register equivalent to the 4133 positive constant. Make a MINUS if so. Don't do this for 4134 a non-negative constant since we might then alternate between 4135 choosing positive and negative constants. Having the positive 4136 constant previously-used is the more common case. Be sure 4137 the resulting constant is non-negative; if const_arg1 were 4138 the smallest negative number this would overflow: depending 4139 on the mode, this would either just be the same value (and 4140 hence not save anything) or be incorrect. */ 4141 if (const_arg1 != 0 && GET_CODE (const_arg1) == CONST_INT 4142 && INTVAL (const_arg1) < 0 4143 /* This used to test 4144 4145 -INTVAL (const_arg1) >= 0 4146 4147 But The Sun V5.0 compilers mis-compiled that test. So 4148 instead we test for the problematic value in a more direct 4149 manner and hope the Sun compilers get it correct. */ 4150 && INTVAL (const_arg1) != 4151 ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT - 1)) 4152 && GET_CODE (folded_arg1) == REG) 4153 { 4154 rtx new_const = GEN_INT (-INTVAL (const_arg1)); 4155 struct table_elt *p 4156 = lookup (new_const, safe_hash (new_const, mode) & HASH_MASK, 4157 mode); 4158 4159 if (p) 4160 for (p = p->first_same_value; p; p = p->next_same_value) 4161 if (GET_CODE (p->exp) == REG) 4162 return simplify_gen_binary (MINUS, mode, folded_arg0, 4163 canon_reg (p->exp, NULL_RTX)); 4164 } 4165 goto from_plus; 4166 4167 case MINUS: 4168 /* If we have (MINUS Y C), see if Y is known to be (PLUS Z C2). 4169 If so, produce (PLUS Z C2-C). */ 4170 if (const_arg1 != 0 && GET_CODE (const_arg1) == CONST_INT) 4171 { 4172 rtx y = lookup_as_function (XEXP (x, 0), PLUS); 4173 if (y && GET_CODE (XEXP (y, 1)) == CONST_INT) 4174 return fold_rtx (plus_constant (copy_rtx (y), 4175 -INTVAL (const_arg1)), 4176 NULL_RTX); 4177 } 4178 4179 /* Fall through. */ 4180 4181 from_plus: 4182 case SMIN: case SMAX: case UMIN: case UMAX: 4183 case IOR: case AND: case XOR: 4184 case MULT: case DIV: case UDIV: 4185 case ASHIFT: case LSHIFTRT: case ASHIFTRT: 4186 /* If we have (<op> <reg> <const_int>) for an associative OP and REG 4187 is known to be of similar form, we may be able to replace the 4188 operation with a combined operation. This may eliminate the 4189 intermediate operation if every use is simplified in this way. 4190 Note that the similar optimization done by combine.c only works 4191 if the intermediate operation's result has only one reference. */ 4192 4193 if (GET_CODE (folded_arg0) == REG 4194 && const_arg1 && GET_CODE (const_arg1) == CONST_INT) 4195 { 4196 int is_shift 4197 = (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT); 4198 rtx y = lookup_as_function (folded_arg0, code); 4199 rtx inner_const; 4200 enum rtx_code associate_code; 4201 rtx new_const; 4202 4203 if (y == 0 4204 || 0 == (inner_const 4205 = equiv_constant (fold_rtx (XEXP (y, 1), 0))) 4206 || GET_CODE (inner_const) != CONST_INT 4207 /* If we have compiled a statement like 4208 "if (x == (x & mask1))", and now are looking at 4209 "x & mask2", we will have a case where the first operand 4210 of Y is the same as our first operand. Unless we detect 4211 this case, an infinite loop will result. */ 4212 || XEXP (y, 0) == folded_arg0) 4213 break; 4214 4215 /* Don't associate these operations if they are a PLUS with the 4216 same constant and it is a power of two. These might be doable 4217 with a pre- or post-increment. Similarly for two subtracts of 4218 identical powers of two with post decrement. */ 4219 4220 if (code == PLUS && INTVAL (const_arg1) == INTVAL (inner_const) 4221 && ((HAVE_PRE_INCREMENT 4222 && exact_log2 (INTVAL (const_arg1)) >= 0) 4223 || (HAVE_POST_INCREMENT 4224 && exact_log2 (INTVAL (const_arg1)) >= 0) 4225 || (HAVE_PRE_DECREMENT 4226 && exact_log2 (- INTVAL (const_arg1)) >= 0) 4227 || (HAVE_POST_DECREMENT 4228 && exact_log2 (- INTVAL (const_arg1)) >= 0))) 4229 break; 4230 4231 /* Compute the code used to compose the constants. For example, 4232 A/C1/C2 is A/(C1 * C2), so if CODE == DIV, we want MULT. */ 4233 4234 associate_code 4235 = (code == MULT || code == DIV || code == UDIV ? MULT 4236 : is_shift || code == PLUS || code == MINUS ? PLUS : code); 4237 4238 new_const = simplify_binary_operation (associate_code, mode, 4239 const_arg1, inner_const); 4240 4241 if (new_const == 0) 4242 break; 4243 4244 /* If we are associating shift operations, don't let this 4245 produce a shift of the size of the object or larger. 4246 This could occur when we follow a sign-extend by a right 4247 shift on a machine that does a sign-extend as a pair 4248 of shifts. */ 4249 4250 if (is_shift && GET_CODE (new_const) == CONST_INT 4251 && INTVAL (new_const) >= GET_MODE_BITSIZE (mode)) 4252 { 4253 /* As an exception, we can turn an ASHIFTRT of this 4254 form into a shift of the number of bits - 1. */ 4255 if (code == ASHIFTRT) 4256 new_const = GEN_INT (GET_MODE_BITSIZE (mode) - 1); 4257 else 4258 break; 4259 } 4260 4261 y = copy_rtx (XEXP (y, 0)); 4262 4263 /* If Y contains our first operand (the most common way this 4264 can happen is if Y is a MEM), we would do into an infinite 4265 loop if we tried to fold it. So don't in that case. */ 4266 4267 if (! reg_mentioned_p (folded_arg0, y)) 4268 y = fold_rtx (y, insn); 4269 4270 return simplify_gen_binary (code, mode, y, new_const); 4271 } 4272 break; 4273 4274 default: 4275 break; 4276 } 4277 4278 new = simplify_binary_operation (code, mode, 4279 const_arg0 ? const_arg0 : folded_arg0, 4280 const_arg1 ? const_arg1 : folded_arg1); 4281 break; 4282 4283 case 'o': 4284 /* (lo_sum (high X) X) is simply X. */ 4285 if (code == LO_SUM && const_arg0 != 0 4286 && GET_CODE (const_arg0) == HIGH 4287 && rtx_equal_p (XEXP (const_arg0, 0), const_arg1)) 4288 return const_arg1; 4289 break; 4290 4291 case '3': 4292 case 'b': 4293 new = simplify_ternary_operation (code, mode, mode_arg0, 4294 const_arg0 ? const_arg0 : folded_arg0, 4295 const_arg1 ? const_arg1 : folded_arg1, 4296 const_arg2 ? const_arg2 : XEXP (x, 2)); 4297 break; 4298 4299 case 'x': 4300 /* Always eliminate CONSTANT_P_RTX at this stage. */ 4301 if (code == CONSTANT_P_RTX) 4302 return (const_arg0 ? const1_rtx : const0_rtx); 4303 break; 4304 } 4305 4306 return new ? new : x; 4307} 4308 4309/* Return a constant value currently equivalent to X. 4310 Return 0 if we don't know one. */ 4311 4312static rtx 4313equiv_constant (x) 4314 rtx x; 4315{ 4316 if (GET_CODE (x) == REG 4317 && REGNO_QTY_VALID_P (REGNO (x))) 4318 { 4319 int x_q = REG_QTY (REGNO (x)); 4320 struct qty_table_elem *x_ent = &qty_table[x_q]; 4321 4322 if (x_ent->const_rtx) 4323 x = gen_lowpart_if_possible (GET_MODE (x), x_ent->const_rtx); 4324 } 4325 4326 if (x == 0 || CONSTANT_P (x)) 4327 return x; 4328 4329 /* If X is a MEM, try to fold it outside the context of any insn to see if 4330 it might be equivalent to a constant. That handles the case where it 4331 is a constant-pool reference. Then try to look it up in the hash table 4332 in case it is something whose value we have seen before. */ 4333 4334 if (GET_CODE (x) == MEM) 4335 { 4336 struct table_elt *elt; 4337 4338 x = fold_rtx (x, NULL_RTX); 4339 if (CONSTANT_P (x)) 4340 return x; 4341 4342 elt = lookup (x, safe_hash (x, GET_MODE (x)) & HASH_MASK, GET_MODE (x)); 4343 if (elt == 0) 4344 return 0; 4345 4346 for (elt = elt->first_same_value; elt; elt = elt->next_same_value) 4347 if (elt->is_const && CONSTANT_P (elt->exp)) 4348 return elt->exp; 4349 } 4350 4351 return 0; 4352} 4353 4354/* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point 4355 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the 4356 least-significant part of X. 4357 MODE specifies how big a part of X to return. 4358 4359 If the requested operation cannot be done, 0 is returned. 4360 4361 This is similar to gen_lowpart in emit-rtl.c. */ 4362 4363rtx 4364gen_lowpart_if_possible (mode, x) 4365 enum machine_mode mode; 4366 rtx x; 4367{ 4368 rtx result = gen_lowpart_common (mode, x); 4369 4370 if (result) 4371 return result; 4372 else if (GET_CODE (x) == MEM) 4373 { 4374 /* This is the only other case we handle. */ 4375 int offset = 0; 4376 rtx new; 4377 4378 if (WORDS_BIG_ENDIAN) 4379 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 4380 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 4381 if (BYTES_BIG_ENDIAN) 4382 /* Adjust the address so that the address-after-the-data is 4383 unchanged. */ 4384 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 4385 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 4386 4387 new = adjust_address_nv (x, mode, offset); 4388 if (! memory_address_p (mode, XEXP (new, 0))) 4389 return 0; 4390 4391 return new; 4392 } 4393 else 4394 return 0; 4395} 4396 4397/* Given INSN, a jump insn, TAKEN indicates if we are following the "taken" 4398 branch. It will be zero if not. 4399 4400 In certain cases, this can cause us to add an equivalence. For example, 4401 if we are following the taken case of 4402 if (i == 2) 4403 we can add the fact that `i' and '2' are now equivalent. 4404 4405 In any case, we can record that this comparison was passed. If the same 4406 comparison is seen later, we will know its value. */ 4407 4408static void 4409record_jump_equiv (insn, taken) 4410 rtx insn; 4411 int taken; 4412{ 4413 int cond_known_true; 4414 rtx op0, op1; 4415 rtx set; 4416 enum machine_mode mode, mode0, mode1; 4417 int reversed_nonequality = 0; 4418 enum rtx_code code; 4419 4420 /* Ensure this is the right kind of insn. */ 4421 if (! any_condjump_p (insn)) 4422 return; 4423 set = pc_set (insn); 4424 4425 /* See if this jump condition is known true or false. */ 4426 if (taken) 4427 cond_known_true = (XEXP (SET_SRC (set), 2) == pc_rtx); 4428 else 4429 cond_known_true = (XEXP (SET_SRC (set), 1) == pc_rtx); 4430 4431 /* Get the type of comparison being done and the operands being compared. 4432 If we had to reverse a non-equality condition, record that fact so we 4433 know that it isn't valid for floating-point. */ 4434 code = GET_CODE (XEXP (SET_SRC (set), 0)); 4435 op0 = fold_rtx (XEXP (XEXP (SET_SRC (set), 0), 0), insn); 4436 op1 = fold_rtx (XEXP (XEXP (SET_SRC (set), 0), 1), insn); 4437 4438 code = find_comparison_args (code, &op0, &op1, &mode0, &mode1); 4439 if (! cond_known_true) 4440 { 4441 code = reversed_comparison_code_parts (code, op0, op1, insn); 4442 4443 /* Don't remember if we can't find the inverse. */ 4444 if (code == UNKNOWN) 4445 return; 4446 } 4447 4448 /* The mode is the mode of the non-constant. */ 4449 mode = mode0; 4450 if (mode1 != VOIDmode) 4451 mode = mode1; 4452 4453 record_jump_cond (code, mode, op0, op1, reversed_nonequality); 4454} 4455 4456/* We know that comparison CODE applied to OP0 and OP1 in MODE is true. 4457 REVERSED_NONEQUALITY is nonzero if CODE had to be swapped. 4458 Make any useful entries we can with that information. Called from 4459 above function and called recursively. */ 4460 4461static void 4462record_jump_cond (code, mode, op0, op1, reversed_nonequality) 4463 enum rtx_code code; 4464 enum machine_mode mode; 4465 rtx op0, op1; 4466 int reversed_nonequality; 4467{ 4468 unsigned op0_hash, op1_hash; 4469 int op0_in_memory, op1_in_memory; 4470 struct table_elt *op0_elt, *op1_elt; 4471 4472 /* If OP0 and OP1 are known equal, and either is a paradoxical SUBREG, 4473 we know that they are also equal in the smaller mode (this is also 4474 true for all smaller modes whether or not there is a SUBREG, but 4475 is not worth testing for with no SUBREG). */ 4476 4477 /* Note that GET_MODE (op0) may not equal MODE. */ 4478 if (code == EQ && GET_CODE (op0) == SUBREG 4479 && (GET_MODE_SIZE (GET_MODE (op0)) 4480 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0))))) 4481 { 4482 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op0)); 4483 rtx tem = gen_lowpart_if_possible (inner_mode, op1); 4484 4485 record_jump_cond (code, mode, SUBREG_REG (op0), 4486 tem ? tem : gen_rtx_SUBREG (inner_mode, op1, 0), 4487 reversed_nonequality); 4488 } 4489 4490 if (code == EQ && GET_CODE (op1) == SUBREG 4491 && (GET_MODE_SIZE (GET_MODE (op1)) 4492 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1))))) 4493 { 4494 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op1)); 4495 rtx tem = gen_lowpart_if_possible (inner_mode, op0); 4496 4497 record_jump_cond (code, mode, SUBREG_REG (op1), 4498 tem ? tem : gen_rtx_SUBREG (inner_mode, op0, 0), 4499 reversed_nonequality); 4500 } 4501 4502 /* Similarly, if this is an NE comparison, and either is a SUBREG 4503 making a smaller mode, we know the whole thing is also NE. */ 4504 4505 /* Note that GET_MODE (op0) may not equal MODE; 4506 if we test MODE instead, we can get an infinite recursion 4507 alternating between two modes each wider than MODE. */ 4508 4509 if (code == NE && GET_CODE (op0) == SUBREG 4510 && subreg_lowpart_p (op0) 4511 && (GET_MODE_SIZE (GET_MODE (op0)) 4512 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0))))) 4513 { 4514 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op0)); 4515 rtx tem = gen_lowpart_if_possible (inner_mode, op1); 4516 4517 record_jump_cond (code, mode, SUBREG_REG (op0), 4518 tem ? tem : gen_rtx_SUBREG (inner_mode, op1, 0), 4519 reversed_nonequality); 4520 } 4521 4522 if (code == NE && GET_CODE (op1) == SUBREG 4523 && subreg_lowpart_p (op1) 4524 && (GET_MODE_SIZE (GET_MODE (op1)) 4525 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1))))) 4526 { 4527 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op1)); 4528 rtx tem = gen_lowpart_if_possible (inner_mode, op0); 4529 4530 record_jump_cond (code, mode, SUBREG_REG (op1), 4531 tem ? tem : gen_rtx_SUBREG (inner_mode, op0, 0), 4532 reversed_nonequality); 4533 } 4534 4535 /* Hash both operands. */ 4536 4537 do_not_record = 0; 4538 hash_arg_in_memory = 0; 4539 op0_hash = HASH (op0, mode); 4540 op0_in_memory = hash_arg_in_memory; 4541 4542 if (do_not_record) 4543 return; 4544 4545 do_not_record = 0; 4546 hash_arg_in_memory = 0; 4547 op1_hash = HASH (op1, mode); 4548 op1_in_memory = hash_arg_in_memory; 4549 4550 if (do_not_record) 4551 return; 4552 4553 /* Look up both operands. */ 4554 op0_elt = lookup (op0, op0_hash, mode); 4555 op1_elt = lookup (op1, op1_hash, mode); 4556 4557 /* If both operands are already equivalent or if they are not in the 4558 table but are identical, do nothing. */ 4559 if ((op0_elt != 0 && op1_elt != 0 4560 && op0_elt->first_same_value == op1_elt->first_same_value) 4561 || op0 == op1 || rtx_equal_p (op0, op1)) 4562 return; 4563 4564 /* If we aren't setting two things equal all we can do is save this 4565 comparison. Similarly if this is floating-point. In the latter 4566 case, OP1 might be zero and both -0.0 and 0.0 are equal to it. 4567 If we record the equality, we might inadvertently delete code 4568 whose intent was to change -0 to +0. */ 4569 4570 if (code != EQ || FLOAT_MODE_P (GET_MODE (op0))) 4571 { 4572 struct qty_table_elem *ent; 4573 int qty; 4574 4575 /* If we reversed a floating-point comparison, if OP0 is not a 4576 register, or if OP1 is neither a register or constant, we can't 4577 do anything. */ 4578 4579 if (GET_CODE (op1) != REG) 4580 op1 = equiv_constant (op1); 4581 4582 if ((reversed_nonequality && FLOAT_MODE_P (mode)) 4583 || GET_CODE (op0) != REG || op1 == 0) 4584 return; 4585 4586 /* Put OP0 in the hash table if it isn't already. This gives it a 4587 new quantity number. */ 4588 if (op0_elt == 0) 4589 { 4590 if (insert_regs (op0, NULL, 0)) 4591 { 4592 rehash_using_reg (op0); 4593 op0_hash = HASH (op0, mode); 4594 4595 /* If OP0 is contained in OP1, this changes its hash code 4596 as well. Faster to rehash than to check, except 4597 for the simple case of a constant. */ 4598 if (! CONSTANT_P (op1)) 4599 op1_hash = HASH (op1,mode); 4600 } 4601 4602 op0_elt = insert (op0, NULL, op0_hash, mode); 4603 op0_elt->in_memory = op0_in_memory; 4604 } 4605 4606 qty = REG_QTY (REGNO (op0)); 4607 ent = &qty_table[qty]; 4608 4609 ent->comparison_code = code; 4610 if (GET_CODE (op1) == REG) 4611 { 4612 /* Look it up again--in case op0 and op1 are the same. */ 4613 op1_elt = lookup (op1, op1_hash, mode); 4614 4615 /* Put OP1 in the hash table so it gets a new quantity number. */ 4616 if (op1_elt == 0) 4617 { 4618 if (insert_regs (op1, NULL, 0)) 4619 { 4620 rehash_using_reg (op1); 4621 op1_hash = HASH (op1, mode); 4622 } 4623 4624 op1_elt = insert (op1, NULL, op1_hash, mode); 4625 op1_elt->in_memory = op1_in_memory; 4626 } 4627 4628 ent->comparison_const = NULL_RTX; 4629 ent->comparison_qty = REG_QTY (REGNO (op1)); 4630 } 4631 else 4632 { 4633 ent->comparison_const = op1; 4634 ent->comparison_qty = -1; 4635 } 4636 4637 return; 4638 } 4639 4640 /* If either side is still missing an equivalence, make it now, 4641 then merge the equivalences. */ 4642 4643 if (op0_elt == 0) 4644 { 4645 if (insert_regs (op0, NULL, 0)) 4646 { 4647 rehash_using_reg (op0); 4648 op0_hash = HASH (op0, mode); 4649 } 4650 4651 op0_elt = insert (op0, NULL, op0_hash, mode); 4652 op0_elt->in_memory = op0_in_memory; 4653 } 4654 4655 if (op1_elt == 0) 4656 { 4657 if (insert_regs (op1, NULL, 0)) 4658 { 4659 rehash_using_reg (op1); 4660 op1_hash = HASH (op1, mode); 4661 } 4662 4663 op1_elt = insert (op1, NULL, op1_hash, mode); 4664 op1_elt->in_memory = op1_in_memory; 4665 } 4666 4667 merge_equiv_classes (op0_elt, op1_elt); 4668 last_jump_equiv_class = op0_elt; 4669} 4670 4671/* CSE processing for one instruction. 4672 First simplify sources and addresses of all assignments 4673 in the instruction, using previously-computed equivalents values. 4674 Then install the new sources and destinations in the table 4675 of available values. 4676 4677 If LIBCALL_INSN is nonzero, don't record any equivalence made in 4678 the insn. It means that INSN is inside libcall block. In this 4679 case LIBCALL_INSN is the corresponding insn with REG_LIBCALL. */ 4680 4681/* Data on one SET contained in the instruction. */ 4682 4683struct set 4684{ 4685 /* The SET rtx itself. */ 4686 rtx rtl; 4687 /* The SET_SRC of the rtx (the original value, if it is changing). */ 4688 rtx src; 4689 /* The hash-table element for the SET_SRC of the SET. */ 4690 struct table_elt *src_elt; 4691 /* Hash value for the SET_SRC. */ 4692 unsigned src_hash; 4693 /* Hash value for the SET_DEST. */ 4694 unsigned dest_hash; 4695 /* The SET_DEST, with SUBREG, etc., stripped. */ 4696 rtx inner_dest; 4697 /* Nonzero if the SET_SRC is in memory. */ 4698 char src_in_memory; 4699 /* Nonzero if the SET_SRC contains something 4700 whose value cannot be predicted and understood. */ 4701 char src_volatile; 4702 /* Original machine mode, in case it becomes a CONST_INT. */ 4703 enum machine_mode mode; 4704 /* A constant equivalent for SET_SRC, if any. */ 4705 rtx src_const; 4706 /* Original SET_SRC value used for libcall notes. */ 4707 rtx orig_src; 4708 /* Hash value of constant equivalent for SET_SRC. */ 4709 unsigned src_const_hash; 4710 /* Table entry for constant equivalent for SET_SRC, if any. */ 4711 struct table_elt *src_const_elt; 4712}; 4713 4714static void 4715cse_insn (insn, libcall_insn) 4716 rtx insn; 4717 rtx libcall_insn; 4718{ 4719 rtx x = PATTERN (insn); 4720 int i; 4721 rtx tem; 4722 int n_sets = 0; 4723 4724#ifdef HAVE_cc0 4725 /* Records what this insn does to set CC0. */ 4726 rtx this_insn_cc0 = 0; 4727 enum machine_mode this_insn_cc0_mode = VOIDmode; 4728#endif 4729 4730 rtx src_eqv = 0; 4731 struct table_elt *src_eqv_elt = 0; 4732 int src_eqv_volatile = 0; 4733 int src_eqv_in_memory = 0; 4734 unsigned src_eqv_hash = 0; 4735 4736 struct set *sets = (struct set *) 0; 4737 4738 this_insn = insn; 4739 4740 /* Find all the SETs and CLOBBERs in this instruction. 4741 Record all the SETs in the array `set' and count them. 4742 Also determine whether there is a CLOBBER that invalidates 4743 all memory references, or all references at varying addresses. */ 4744 4745 if (GET_CODE (insn) == CALL_INSN) 4746 { 4747 for (tem = CALL_INSN_FUNCTION_USAGE (insn); tem; tem = XEXP (tem, 1)) 4748 { 4749 if (GET_CODE (XEXP (tem, 0)) == CLOBBER) 4750 invalidate (SET_DEST (XEXP (tem, 0)), VOIDmode); 4751 XEXP (tem, 0) = canon_reg (XEXP (tem, 0), insn); 4752 } 4753 } 4754 4755 if (GET_CODE (x) == SET) 4756 { 4757 sets = (struct set *) alloca (sizeof (struct set)); 4758 sets[0].rtl = x; 4759 4760 /* Ignore SETs that are unconditional jumps. 4761 They never need cse processing, so this does not hurt. 4762 The reason is not efficiency but rather 4763 so that we can test at the end for instructions 4764 that have been simplified to unconditional jumps 4765 and not be misled by unchanged instructions 4766 that were unconditional jumps to begin with. */ 4767 if (SET_DEST (x) == pc_rtx 4768 && GET_CODE (SET_SRC (x)) == LABEL_REF) 4769 ; 4770 4771 /* Don't count call-insns, (set (reg 0) (call ...)), as a set. 4772 The hard function value register is used only once, to copy to 4773 someplace else, so it isn't worth cse'ing (and on 80386 is unsafe)! 4774 Ensure we invalidate the destination register. On the 80386 no 4775 other code would invalidate it since it is a fixed_reg. 4776 We need not check the return of apply_change_group; see canon_reg. */ 4777 4778 else if (GET_CODE (SET_SRC (x)) == CALL) 4779 { 4780 canon_reg (SET_SRC (x), insn); 4781 apply_change_group (); 4782 fold_rtx (SET_SRC (x), insn); 4783 invalidate (SET_DEST (x), VOIDmode); 4784 } 4785 else 4786 n_sets = 1; 4787 } 4788 else if (GET_CODE (x) == PARALLEL) 4789 { 4790 int lim = XVECLEN (x, 0); 4791 4792 sets = (struct set *) alloca (lim * sizeof (struct set)); 4793 4794 /* Find all regs explicitly clobbered in this insn, 4795 and ensure they are not replaced with any other regs 4796 elsewhere in this insn. 4797 When a reg that is clobbered is also used for input, 4798 we should presume that that is for a reason, 4799 and we should not substitute some other register 4800 which is not supposed to be clobbered. 4801 Therefore, this loop cannot be merged into the one below 4802 because a CALL may precede a CLOBBER and refer to the 4803 value clobbered. We must not let a canonicalization do 4804 anything in that case. */ 4805 for (i = 0; i < lim; i++) 4806 { 4807 rtx y = XVECEXP (x, 0, i); 4808 if (GET_CODE (y) == CLOBBER) 4809 { 4810 rtx clobbered = XEXP (y, 0); 4811 4812 if (GET_CODE (clobbered) == REG 4813 || GET_CODE (clobbered) == SUBREG) 4814 invalidate (clobbered, VOIDmode); 4815 else if (GET_CODE (clobbered) == STRICT_LOW_PART 4816 || GET_CODE (clobbered) == ZERO_EXTRACT) 4817 invalidate (XEXP (clobbered, 0), GET_MODE (clobbered)); 4818 } 4819 } 4820 4821 for (i = 0; i < lim; i++) 4822 { 4823 rtx y = XVECEXP (x, 0, i); 4824 if (GET_CODE (y) == SET) 4825 { 4826 /* As above, we ignore unconditional jumps and call-insns and 4827 ignore the result of apply_change_group. */ 4828 if (GET_CODE (SET_SRC (y)) == CALL) 4829 { 4830 canon_reg (SET_SRC (y), insn); 4831 apply_change_group (); 4832 fold_rtx (SET_SRC (y), insn); 4833 invalidate (SET_DEST (y), VOIDmode); 4834 } 4835 else if (SET_DEST (y) == pc_rtx 4836 && GET_CODE (SET_SRC (y)) == LABEL_REF) 4837 ; 4838 else 4839 sets[n_sets++].rtl = y; 4840 } 4841 else if (GET_CODE (y) == CLOBBER) 4842 { 4843 /* If we clobber memory, canon the address. 4844 This does nothing when a register is clobbered 4845 because we have already invalidated the reg. */ 4846 if (GET_CODE (XEXP (y, 0)) == MEM) 4847 canon_reg (XEXP (y, 0), NULL_RTX); 4848 } 4849 else if (GET_CODE (y) == USE 4850 && ! (GET_CODE (XEXP (y, 0)) == REG 4851 && REGNO (XEXP (y, 0)) < FIRST_PSEUDO_REGISTER)) 4852 canon_reg (y, NULL_RTX); 4853 else if (GET_CODE (y) == CALL) 4854 { 4855 /* The result of apply_change_group can be ignored; see 4856 canon_reg. */ 4857 canon_reg (y, insn); 4858 apply_change_group (); 4859 fold_rtx (y, insn); 4860 } 4861 } 4862 } 4863 else if (GET_CODE (x) == CLOBBER) 4864 { 4865 if (GET_CODE (XEXP (x, 0)) == MEM) 4866 canon_reg (XEXP (x, 0), NULL_RTX); 4867 } 4868 4869 /* Canonicalize a USE of a pseudo register or memory location. */ 4870 else if (GET_CODE (x) == USE 4871 && ! (GET_CODE (XEXP (x, 0)) == REG 4872 && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER)) 4873 canon_reg (XEXP (x, 0), NULL_RTX); 4874 else if (GET_CODE (x) == CALL) 4875 { 4876 /* The result of apply_change_group can be ignored; see canon_reg. */ 4877 canon_reg (x, insn); 4878 apply_change_group (); 4879 fold_rtx (x, insn); 4880 } 4881 4882 /* Store the equivalent value in SRC_EQV, if different, or if the DEST 4883 is a STRICT_LOW_PART. The latter condition is necessary because SRC_EQV 4884 is handled specially for this case, and if it isn't set, then there will 4885 be no equivalence for the destination. */ 4886 if (n_sets == 1 && REG_NOTES (insn) != 0 4887 && (tem = find_reg_note (insn, REG_EQUAL, NULL_RTX)) != 0 4888 && (! rtx_equal_p (XEXP (tem, 0), SET_SRC (sets[0].rtl)) 4889 || GET_CODE (SET_DEST (sets[0].rtl)) == STRICT_LOW_PART)) 4890 src_eqv = canon_reg (XEXP (tem, 0), NULL_RTX); 4891 4892 /* Canonicalize sources and addresses of destinations. 4893 We do this in a separate pass to avoid problems when a MATCH_DUP is 4894 present in the insn pattern. In that case, we want to ensure that 4895 we don't break the duplicate nature of the pattern. So we will replace 4896 both operands at the same time. Otherwise, we would fail to find an 4897 equivalent substitution in the loop calling validate_change below. 4898 4899 We used to suppress canonicalization of DEST if it appears in SRC, 4900 but we don't do this any more. */ 4901 4902 for (i = 0; i < n_sets; i++) 4903 { 4904 rtx dest = SET_DEST (sets[i].rtl); 4905 rtx src = SET_SRC (sets[i].rtl); 4906 rtx new = canon_reg (src, insn); 4907 int insn_code; 4908 4909 sets[i].orig_src = src; 4910 if ((GET_CODE (new) == REG && GET_CODE (src) == REG 4911 && ((REGNO (new) < FIRST_PSEUDO_REGISTER) 4912 != (REGNO (src) < FIRST_PSEUDO_REGISTER))) 4913 || (insn_code = recog_memoized (insn)) < 0 4914 || insn_data[insn_code].n_dups > 0) 4915 validate_change (insn, &SET_SRC (sets[i].rtl), new, 1); 4916 else 4917 SET_SRC (sets[i].rtl) = new; 4918 4919 if (GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SIGN_EXTRACT) 4920 { 4921 validate_change (insn, &XEXP (dest, 1), 4922 canon_reg (XEXP (dest, 1), insn), 1); 4923 validate_change (insn, &XEXP (dest, 2), 4924 canon_reg (XEXP (dest, 2), insn), 1); 4925 } 4926 4927 while (GET_CODE (dest) == SUBREG || GET_CODE (dest) == STRICT_LOW_PART 4928 || GET_CODE (dest) == ZERO_EXTRACT 4929 || GET_CODE (dest) == SIGN_EXTRACT) 4930 dest = XEXP (dest, 0); 4931 4932 if (GET_CODE (dest) == MEM) 4933 canon_reg (dest, insn); 4934 } 4935 4936 /* Now that we have done all the replacements, we can apply the change 4937 group and see if they all work. Note that this will cause some 4938 canonicalizations that would have worked individually not to be applied 4939 because some other canonicalization didn't work, but this should not 4940 occur often. 4941 4942 The result of apply_change_group can be ignored; see canon_reg. */ 4943 4944 apply_change_group (); 4945 4946 /* Set sets[i].src_elt to the class each source belongs to. 4947 Detect assignments from or to volatile things 4948 and set set[i] to zero so they will be ignored 4949 in the rest of this function. 4950 4951 Nothing in this loop changes the hash table or the register chains. */ 4952 4953 for (i = 0; i < n_sets; i++) 4954 { 4955 rtx src, dest; 4956 rtx src_folded; 4957 struct table_elt *elt = 0, *p; 4958 enum machine_mode mode; 4959 rtx src_eqv_here; 4960 rtx src_const = 0; 4961 rtx src_related = 0; 4962 struct table_elt *src_const_elt = 0; 4963 int src_cost = MAX_COST; 4964 int src_eqv_cost = MAX_COST; 4965 int src_folded_cost = MAX_COST; 4966 int src_related_cost = MAX_COST; 4967 int src_elt_cost = MAX_COST; 4968 int src_regcost = MAX_COST; 4969 int src_eqv_regcost = MAX_COST; 4970 int src_folded_regcost = MAX_COST; 4971 int src_related_regcost = MAX_COST; 4972 int src_elt_regcost = MAX_COST; 4973 /* Set non-zero if we need to call force_const_mem on with the 4974 contents of src_folded before using it. */ 4975 int src_folded_force_flag = 0; 4976 4977 dest = SET_DEST (sets[i].rtl); 4978 src = SET_SRC (sets[i].rtl); 4979 4980 /* If SRC is a constant that has no machine mode, 4981 hash it with the destination's machine mode. 4982 This way we can keep different modes separate. */ 4983 4984 mode = GET_MODE (src) == VOIDmode ? GET_MODE (dest) : GET_MODE (src); 4985 sets[i].mode = mode; 4986 4987 if (src_eqv) 4988 { 4989 enum machine_mode eqvmode = mode; 4990 if (GET_CODE (dest) == STRICT_LOW_PART) 4991 eqvmode = GET_MODE (SUBREG_REG (XEXP (dest, 0))); 4992 do_not_record = 0; 4993 hash_arg_in_memory = 0; 4994 src_eqv = fold_rtx (src_eqv, insn); 4995 src_eqv_hash = HASH (src_eqv, eqvmode); 4996 4997 /* Find the equivalence class for the equivalent expression. */ 4998 4999 if (!do_not_record) 5000 src_eqv_elt = lookup (src_eqv, src_eqv_hash, eqvmode); 5001 5002 src_eqv_volatile = do_not_record; 5003 src_eqv_in_memory = hash_arg_in_memory; 5004 } 5005 5006 /* If this is a STRICT_LOW_PART assignment, src_eqv corresponds to the 5007 value of the INNER register, not the destination. So it is not 5008 a valid substitution for the source. But save it for later. */ 5009 if (GET_CODE (dest) == STRICT_LOW_PART) 5010 src_eqv_here = 0; 5011 else 5012 src_eqv_here = src_eqv; 5013 5014 /* Simplify and foldable subexpressions in SRC. Then get the fully- 5015 simplified result, which may not necessarily be valid. */ 5016 src_folded = fold_rtx (src, insn); 5017 5018#if 0 5019 /* ??? This caused bad code to be generated for the m68k port with -O2. 5020 Suppose src is (CONST_INT -1), and that after truncation src_folded 5021 is (CONST_INT 3). Suppose src_folded is then used for src_const. 5022 At the end we will add src and src_const to the same equivalence 5023 class. We now have 3 and -1 on the same equivalence class. This 5024 causes later instructions to be mis-optimized. */ 5025 /* If storing a constant in a bitfield, pre-truncate the constant 5026 so we will be able to record it later. */ 5027 if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT 5028 || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT) 5029 { 5030 rtx width = XEXP (SET_DEST (sets[i].rtl), 1); 5031 5032 if (GET_CODE (src) == CONST_INT 5033 && GET_CODE (width) == CONST_INT 5034 && INTVAL (width) < HOST_BITS_PER_WIDE_INT 5035 && (INTVAL (src) & ((HOST_WIDE_INT) (-1) << INTVAL (width)))) 5036 src_folded 5037 = GEN_INT (INTVAL (src) & (((HOST_WIDE_INT) 1 5038 << INTVAL (width)) - 1)); 5039 } 5040#endif 5041 5042 /* Compute SRC's hash code, and also notice if it 5043 should not be recorded at all. In that case, 5044 prevent any further processing of this assignment. */ 5045 do_not_record = 0; 5046 hash_arg_in_memory = 0; 5047 5048 sets[i].src = src; 5049 sets[i].src_hash = HASH (src, mode); 5050 sets[i].src_volatile = do_not_record; 5051 sets[i].src_in_memory = hash_arg_in_memory; 5052 5053 /* If SRC is a MEM, there is a REG_EQUIV note for SRC, and DEST is 5054 a pseudo, do not record SRC. Using SRC as a replacement for 5055 anything else will be incorrect in that situation. Note that 5056 this usually occurs only for stack slots, in which case all the 5057 RTL would be referring to SRC, so we don't lose any optimization 5058 opportunities by not having SRC in the hash table. */ 5059 5060 if (GET_CODE (src) == MEM 5061 && find_reg_note (insn, REG_EQUIV, NULL_RTX) != 0 5062 && GET_CODE (dest) == REG 5063 && REGNO (dest) >= FIRST_PSEUDO_REGISTER) 5064 sets[i].src_volatile = 1; 5065 5066#if 0 5067 /* It is no longer clear why we used to do this, but it doesn't 5068 appear to still be needed. So let's try without it since this 5069 code hurts cse'ing widened ops. */ 5070 /* If source is a perverse subreg (such as QI treated as an SI), 5071 treat it as volatile. It may do the work of an SI in one context 5072 where the extra bits are not being used, but cannot replace an SI 5073 in general. */ 5074 if (GET_CODE (src) == SUBREG 5075 && (GET_MODE_SIZE (GET_MODE (src)) 5076 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))))) 5077 sets[i].src_volatile = 1; 5078#endif 5079 5080 /* Locate all possible equivalent forms for SRC. Try to replace 5081 SRC in the insn with each cheaper equivalent. 5082 5083 We have the following types of equivalents: SRC itself, a folded 5084 version, a value given in a REG_EQUAL note, or a value related 5085 to a constant. 5086 5087 Each of these equivalents may be part of an additional class 5088 of equivalents (if more than one is in the table, they must be in 5089 the same class; we check for this). 5090 5091 If the source is volatile, we don't do any table lookups. 5092 5093 We note any constant equivalent for possible later use in a 5094 REG_NOTE. */ 5095 5096 if (!sets[i].src_volatile) 5097 elt = lookup (src, sets[i].src_hash, mode); 5098 5099 sets[i].src_elt = elt; 5100 5101 if (elt && src_eqv_here && src_eqv_elt) 5102 { 5103 if (elt->first_same_value != src_eqv_elt->first_same_value) 5104 { 5105 /* The REG_EQUAL is indicating that two formerly distinct 5106 classes are now equivalent. So merge them. */ 5107 merge_equiv_classes (elt, src_eqv_elt); 5108 src_eqv_hash = HASH (src_eqv, elt->mode); 5109 src_eqv_elt = lookup (src_eqv, src_eqv_hash, elt->mode); 5110 } 5111 5112 src_eqv_here = 0; 5113 } 5114 5115 else if (src_eqv_elt) 5116 elt = src_eqv_elt; 5117 5118 /* Try to find a constant somewhere and record it in `src_const'. 5119 Record its table element, if any, in `src_const_elt'. Look in 5120 any known equivalences first. (If the constant is not in the 5121 table, also set `sets[i].src_const_hash'). */ 5122 if (elt) 5123 for (p = elt->first_same_value; p; p = p->next_same_value) 5124 if (p->is_const) 5125 { 5126 src_const = p->exp; 5127 src_const_elt = elt; 5128 break; 5129 } 5130 5131 if (src_const == 0 5132 && (CONSTANT_P (src_folded) 5133 /* Consider (minus (label_ref L1) (label_ref L2)) as 5134 "constant" here so we will record it. This allows us 5135 to fold switch statements when an ADDR_DIFF_VEC is used. */ 5136 || (GET_CODE (src_folded) == MINUS 5137 && GET_CODE (XEXP (src_folded, 0)) == LABEL_REF 5138 && GET_CODE (XEXP (src_folded, 1)) == LABEL_REF))) 5139 src_const = src_folded, src_const_elt = elt; 5140 else if (src_const == 0 && src_eqv_here && CONSTANT_P (src_eqv_here)) 5141 src_const = src_eqv_here, src_const_elt = src_eqv_elt; 5142 5143 /* If we don't know if the constant is in the table, get its 5144 hash code and look it up. */ 5145 if (src_const && src_const_elt == 0) 5146 { 5147 sets[i].src_const_hash = HASH (src_const, mode); 5148 src_const_elt = lookup (src_const, sets[i].src_const_hash, mode); 5149 } 5150 5151 sets[i].src_const = src_const; 5152 sets[i].src_const_elt = src_const_elt; 5153 5154 /* If the constant and our source are both in the table, mark them as 5155 equivalent. Otherwise, if a constant is in the table but the source 5156 isn't, set ELT to it. */ 5157 if (src_const_elt && elt 5158 && src_const_elt->first_same_value != elt->first_same_value) 5159 merge_equiv_classes (elt, src_const_elt); 5160 else if (src_const_elt && elt == 0) 5161 elt = src_const_elt; 5162 5163 /* See if there is a register linearly related to a constant 5164 equivalent of SRC. */ 5165 if (src_const 5166 && (GET_CODE (src_const) == CONST 5167 || (src_const_elt && src_const_elt->related_value != 0))) 5168 { 5169 src_related = use_related_value (src_const, src_const_elt); 5170 if (src_related) 5171 { 5172 struct table_elt *src_related_elt 5173 = lookup (src_related, HASH (src_related, mode), mode); 5174 if (src_related_elt && elt) 5175 { 5176 if (elt->first_same_value 5177 != src_related_elt->first_same_value) 5178 /* This can occur when we previously saw a CONST 5179 involving a SYMBOL_REF and then see the SYMBOL_REF 5180 twice. Merge the involved classes. */ 5181 merge_equiv_classes (elt, src_related_elt); 5182 5183 src_related = 0; 5184 src_related_elt = 0; 5185 } 5186 else if (src_related_elt && elt == 0) 5187 elt = src_related_elt; 5188 } 5189 } 5190 5191 /* See if we have a CONST_INT that is already in a register in a 5192 wider mode. */ 5193 5194 if (src_const && src_related == 0 && GET_CODE (src_const) == CONST_INT 5195 && GET_MODE_CLASS (mode) == MODE_INT 5196 && GET_MODE_BITSIZE (mode) < BITS_PER_WORD) 5197 { 5198 enum machine_mode wider_mode; 5199 5200 for (wider_mode = GET_MODE_WIDER_MODE (mode); 5201 GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD 5202 && src_related == 0; 5203 wider_mode = GET_MODE_WIDER_MODE (wider_mode)) 5204 { 5205 struct table_elt *const_elt 5206 = lookup (src_const, HASH (src_const, wider_mode), wider_mode); 5207 5208 if (const_elt == 0) 5209 continue; 5210 5211 for (const_elt = const_elt->first_same_value; 5212 const_elt; const_elt = const_elt->next_same_value) 5213 if (GET_CODE (const_elt->exp) == REG) 5214 { 5215 src_related = gen_lowpart_if_possible (mode, 5216 const_elt->exp); 5217 break; 5218 } 5219 } 5220 } 5221 5222 /* Another possibility is that we have an AND with a constant in 5223 a mode narrower than a word. If so, it might have been generated 5224 as part of an "if" which would narrow the AND. If we already 5225 have done the AND in a wider mode, we can use a SUBREG of that 5226 value. */ 5227 5228 if (flag_expensive_optimizations && ! src_related 5229 && GET_CODE (src) == AND && GET_CODE (XEXP (src, 1)) == CONST_INT 5230 && GET_MODE_SIZE (mode) < UNITS_PER_WORD) 5231 { 5232 enum machine_mode tmode; 5233 rtx new_and = gen_rtx_AND (VOIDmode, NULL_RTX, XEXP (src, 1)); 5234 5235 for (tmode = GET_MODE_WIDER_MODE (mode); 5236 GET_MODE_SIZE (tmode) <= UNITS_PER_WORD; 5237 tmode = GET_MODE_WIDER_MODE (tmode)) 5238 { 5239 rtx inner = gen_lowpart_if_possible (tmode, XEXP (src, 0)); 5240 struct table_elt *larger_elt; 5241 5242 if (inner) 5243 { 5244 PUT_MODE (new_and, tmode); 5245 XEXP (new_and, 0) = inner; 5246 larger_elt = lookup (new_and, HASH (new_and, tmode), tmode); 5247 if (larger_elt == 0) 5248 continue; 5249 5250 for (larger_elt = larger_elt->first_same_value; 5251 larger_elt; larger_elt = larger_elt->next_same_value) 5252 if (GET_CODE (larger_elt->exp) == REG) 5253 { 5254 src_related 5255 = gen_lowpart_if_possible (mode, larger_elt->exp); 5256 break; 5257 } 5258 5259 if (src_related) 5260 break; 5261 } 5262 } 5263 } 5264 5265#ifdef LOAD_EXTEND_OP 5266 /* See if a MEM has already been loaded with a widening operation; 5267 if it has, we can use a subreg of that. Many CISC machines 5268 also have such operations, but this is only likely to be 5269 beneficial these machines. */ 5270 5271 if (flag_expensive_optimizations && src_related == 0 5272 && (GET_MODE_SIZE (mode) < UNITS_PER_WORD) 5273 && GET_MODE_CLASS (mode) == MODE_INT 5274 && GET_CODE (src) == MEM && ! do_not_record 5275 && LOAD_EXTEND_OP (mode) != NIL) 5276 { 5277 enum machine_mode tmode; 5278 5279 /* Set what we are trying to extend and the operation it might 5280 have been extended with. */ 5281 PUT_CODE (memory_extend_rtx, LOAD_EXTEND_OP (mode)); 5282 XEXP (memory_extend_rtx, 0) = src; 5283 5284 for (tmode = GET_MODE_WIDER_MODE (mode); 5285 GET_MODE_SIZE (tmode) <= UNITS_PER_WORD; 5286 tmode = GET_MODE_WIDER_MODE (tmode)) 5287 { 5288 struct table_elt *larger_elt; 5289 5290 PUT_MODE (memory_extend_rtx, tmode); 5291 larger_elt = lookup (memory_extend_rtx, 5292 HASH (memory_extend_rtx, tmode), tmode); 5293 if (larger_elt == 0) 5294 continue; 5295 5296 for (larger_elt = larger_elt->first_same_value; 5297 larger_elt; larger_elt = larger_elt->next_same_value) 5298 if (GET_CODE (larger_elt->exp) == REG) 5299 { 5300 src_related = gen_lowpart_if_possible (mode, 5301 larger_elt->exp); 5302 break; 5303 } 5304 5305 if (src_related) 5306 break; 5307 } 5308 } 5309#endif /* LOAD_EXTEND_OP */ 5310 5311 if (src == src_folded) 5312 src_folded = 0; 5313 5314 /* At this point, ELT, if non-zero, points to a class of expressions 5315 equivalent to the source of this SET and SRC, SRC_EQV, SRC_FOLDED, 5316 and SRC_RELATED, if non-zero, each contain additional equivalent 5317 expressions. Prune these latter expressions by deleting expressions 5318 already in the equivalence class. 5319 5320 Check for an equivalent identical to the destination. If found, 5321 this is the preferred equivalent since it will likely lead to 5322 elimination of the insn. Indicate this by placing it in 5323 `src_related'. */ 5324 5325 if (elt) 5326 elt = elt->first_same_value; 5327 for (p = elt; p; p = p->next_same_value) 5328 { 5329 enum rtx_code code = GET_CODE (p->exp); 5330 5331 /* If the expression is not valid, ignore it. Then we do not 5332 have to check for validity below. In most cases, we can use 5333 `rtx_equal_p', since canonicalization has already been done. */ 5334 if (code != REG && ! exp_equiv_p (p->exp, p->exp, 1, 0)) 5335 continue; 5336 5337 /* Also skip paradoxical subregs, unless that's what we're 5338 looking for. */ 5339 if (code == SUBREG 5340 && (GET_MODE_SIZE (GET_MODE (p->exp)) 5341 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (p->exp)))) 5342 && ! (src != 0 5343 && GET_CODE (src) == SUBREG 5344 && GET_MODE (src) == GET_MODE (p->exp) 5345 && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))) 5346 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (p->exp)))))) 5347 continue; 5348 5349 if (src && GET_CODE (src) == code && rtx_equal_p (src, p->exp)) 5350 src = 0; 5351 else if (src_folded && GET_CODE (src_folded) == code 5352 && rtx_equal_p (src_folded, p->exp)) 5353 src_folded = 0; 5354 else if (src_eqv_here && GET_CODE (src_eqv_here) == code 5355 && rtx_equal_p (src_eqv_here, p->exp)) 5356 src_eqv_here = 0; 5357 else if (src_related && GET_CODE (src_related) == code 5358 && rtx_equal_p (src_related, p->exp)) 5359 src_related = 0; 5360 5361 /* This is the same as the destination of the insns, we want 5362 to prefer it. Copy it to src_related. The code below will 5363 then give it a negative cost. */ 5364 if (GET_CODE (dest) == code && rtx_equal_p (p->exp, dest)) 5365 src_related = dest; 5366 } 5367 5368 /* Find the cheapest valid equivalent, trying all the available 5369 possibilities. Prefer items not in the hash table to ones 5370 that are when they are equal cost. Note that we can never 5371 worsen an insn as the current contents will also succeed. 5372 If we find an equivalent identical to the destination, use it as best, 5373 since this insn will probably be eliminated in that case. */ 5374 if (src) 5375 { 5376 if (rtx_equal_p (src, dest)) 5377 src_cost = src_regcost = -1; 5378 else 5379 { 5380 src_cost = COST (src); 5381 src_regcost = approx_reg_cost (src); 5382 } 5383 } 5384 5385 if (src_eqv_here) 5386 { 5387 if (rtx_equal_p (src_eqv_here, dest)) 5388 src_eqv_cost = src_eqv_regcost = -1; 5389 else 5390 { 5391 src_eqv_cost = COST (src_eqv_here); 5392 src_eqv_regcost = approx_reg_cost (src_eqv_here); 5393 } 5394 } 5395 5396 if (src_folded) 5397 { 5398 if (rtx_equal_p (src_folded, dest)) 5399 src_folded_cost = src_folded_regcost = -1; 5400 else 5401 { 5402 src_folded_cost = COST (src_folded); 5403 src_folded_regcost = approx_reg_cost (src_folded); 5404 } 5405 } 5406 5407 if (src_related) 5408 { 5409 if (rtx_equal_p (src_related, dest)) 5410 src_related_cost = src_related_regcost = -1; 5411 else 5412 { 5413 src_related_cost = COST (src_related); 5414 src_related_regcost = approx_reg_cost (src_related); 5415 } 5416 } 5417 5418 /* If this was an indirect jump insn, a known label will really be 5419 cheaper even though it looks more expensive. */ 5420 if (dest == pc_rtx && src_const && GET_CODE (src_const) == LABEL_REF) 5421 src_folded = src_const, src_folded_cost = src_folded_regcost = -1; 5422 5423 /* Terminate loop when replacement made. This must terminate since 5424 the current contents will be tested and will always be valid. */ 5425 while (1) 5426 { 5427 rtx trial; 5428 5429 /* Skip invalid entries. */ 5430 while (elt && GET_CODE (elt->exp) != REG 5431 && ! exp_equiv_p (elt->exp, elt->exp, 1, 0)) 5432 elt = elt->next_same_value; 5433 5434 /* A paradoxical subreg would be bad here: it'll be the right 5435 size, but later may be adjusted so that the upper bits aren't 5436 what we want. So reject it. */ 5437 if (elt != 0 5438 && GET_CODE (elt->exp) == SUBREG 5439 && (GET_MODE_SIZE (GET_MODE (elt->exp)) 5440 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (elt->exp)))) 5441 /* It is okay, though, if the rtx we're trying to match 5442 will ignore any of the bits we can't predict. */ 5443 && ! (src != 0 5444 && GET_CODE (src) == SUBREG 5445 && GET_MODE (src) == GET_MODE (elt->exp) 5446 && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))) 5447 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (elt->exp)))))) 5448 { 5449 elt = elt->next_same_value; 5450 continue; 5451 } 5452 5453 if (elt) 5454 { 5455 src_elt_cost = elt->cost; 5456 src_elt_regcost = elt->regcost; 5457 } 5458 5459 /* Find cheapest and skip it for the next time. For items 5460 of equal cost, use this order: 5461 src_folded, src, src_eqv, src_related and hash table entry. */ 5462 if (src_folded 5463 && preferrable (src_folded_cost, src_folded_regcost, 5464 src_cost, src_regcost) <= 0 5465 && preferrable (src_folded_cost, src_folded_regcost, 5466 src_eqv_cost, src_eqv_regcost) <= 0 5467 && preferrable (src_folded_cost, src_folded_regcost, 5468 src_related_cost, src_related_regcost) <= 0 5469 && preferrable (src_folded_cost, src_folded_regcost, 5470 src_elt_cost, src_elt_regcost) <= 0) 5471 { 5472 trial = src_folded, src_folded_cost = MAX_COST; 5473 if (src_folded_force_flag) 5474 trial = force_const_mem (mode, trial); 5475 } 5476 else if (src 5477 && preferrable (src_cost, src_regcost, 5478 src_eqv_cost, src_eqv_regcost) <= 0 5479 && preferrable (src_cost, src_regcost, 5480 src_related_cost, src_related_regcost) <= 0 5481 && preferrable (src_cost, src_regcost, 5482 src_elt_cost, src_elt_regcost) <= 0) 5483 trial = src, src_cost = MAX_COST; 5484 else if (src_eqv_here 5485 && preferrable (src_eqv_cost, src_eqv_regcost, 5486 src_related_cost, src_related_regcost) <= 0 5487 && preferrable (src_eqv_cost, src_eqv_regcost, 5488 src_elt_cost, src_elt_regcost) <= 0) 5489 trial = copy_rtx (src_eqv_here), src_eqv_cost = MAX_COST; 5490 else if (src_related 5491 && preferrable (src_related_cost, src_related_regcost, 5492 src_elt_cost, src_elt_regcost) <= 0) 5493 trial = copy_rtx (src_related), src_related_cost = MAX_COST; 5494 else 5495 { 5496 trial = copy_rtx (elt->exp); 5497 elt = elt->next_same_value; 5498 src_elt_cost = MAX_COST; 5499 } 5500 5501 /* We don't normally have an insn matching (set (pc) (pc)), so 5502 check for this separately here. We will delete such an 5503 insn below. 5504 5505 For other cases such as a table jump or conditional jump 5506 where we know the ultimate target, go ahead and replace the 5507 operand. While that may not make a valid insn, we will 5508 reemit the jump below (and also insert any necessary 5509 barriers). */ 5510 if (n_sets == 1 && dest == pc_rtx 5511 && (trial == pc_rtx 5512 || (GET_CODE (trial) == LABEL_REF 5513 && ! condjump_p (insn)))) 5514 { 5515 SET_SRC (sets[i].rtl) = trial; 5516 cse_jumps_altered = 1; 5517 break; 5518 } 5519 5520 /* Look for a substitution that makes a valid insn. */ 5521 else if (validate_change (insn, &SET_SRC (sets[i].rtl), trial, 0)) 5522 { 5523 /* If we just made a substitution inside a libcall, then we 5524 need to make the same substitution in any notes attached 5525 to the RETVAL insn. */ 5526 if (libcall_insn 5527 && (GET_CODE (sets[i].orig_src) == REG 5528 || GET_CODE (sets[i].orig_src) == SUBREG 5529 || GET_CODE (sets[i].orig_src) == MEM)) 5530 replace_rtx (REG_NOTES (libcall_insn), sets[i].orig_src, 5531 canon_reg (SET_SRC (sets[i].rtl), insn)); 5532 5533 /* The result of apply_change_group can be ignored; see 5534 canon_reg. */ 5535 5536 validate_change (insn, &SET_SRC (sets[i].rtl), 5537 canon_reg (SET_SRC (sets[i].rtl), insn), 5538 1); 5539 apply_change_group (); 5540 break; 5541 } 5542 5543 /* If we previously found constant pool entries for 5544 constants and this is a constant, try making a 5545 pool entry. Put it in src_folded unless we already have done 5546 this since that is where it likely came from. */ 5547 5548 else if (constant_pool_entries_cost 5549 && CONSTANT_P (trial) 5550 /* Reject cases that will abort in decode_rtx_const. 5551 On the alpha when simplifying a switch, we get 5552 (const (truncate (minus (label_ref) (label_ref)))). */ 5553 && ! (GET_CODE (trial) == CONST 5554 && GET_CODE (XEXP (trial, 0)) == TRUNCATE) 5555 /* Likewise on IA-64, except without the truncate. */ 5556 && ! (GET_CODE (trial) == CONST 5557 && GET_CODE (XEXP (trial, 0)) == MINUS 5558 && GET_CODE (XEXP (XEXP (trial, 0), 0)) == LABEL_REF 5559 && GET_CODE (XEXP (XEXP (trial, 0), 1)) == LABEL_REF) 5560 && (src_folded == 0 5561 || (GET_CODE (src_folded) != MEM 5562 && ! src_folded_force_flag)) 5563 && GET_MODE_CLASS (mode) != MODE_CC 5564 && mode != VOIDmode) 5565 { 5566 src_folded_force_flag = 1; 5567 src_folded = trial; 5568 src_folded_cost = constant_pool_entries_cost; 5569 } 5570 } 5571 5572 src = SET_SRC (sets[i].rtl); 5573 5574 /* In general, it is good to have a SET with SET_SRC == SET_DEST. 5575 However, there is an important exception: If both are registers 5576 that are not the head of their equivalence class, replace SET_SRC 5577 with the head of the class. If we do not do this, we will have 5578 both registers live over a portion of the basic block. This way, 5579 their lifetimes will likely abut instead of overlapping. */ 5580 if (GET_CODE (dest) == REG 5581 && REGNO_QTY_VALID_P (REGNO (dest))) 5582 { 5583 int dest_q = REG_QTY (REGNO (dest)); 5584 struct qty_table_elem *dest_ent = &qty_table[dest_q]; 5585 5586 if (dest_ent->mode == GET_MODE (dest) 5587 && dest_ent->first_reg != REGNO (dest) 5588 && GET_CODE (src) == REG && REGNO (src) == REGNO (dest) 5589 /* Don't do this if the original insn had a hard reg as 5590 SET_SRC or SET_DEST. */ 5591 && (GET_CODE (sets[i].src) != REG 5592 || REGNO (sets[i].src) >= FIRST_PSEUDO_REGISTER) 5593 && (GET_CODE (dest) != REG || REGNO (dest) >= FIRST_PSEUDO_REGISTER)) 5594 /* We can't call canon_reg here because it won't do anything if 5595 SRC is a hard register. */ 5596 { 5597 int src_q = REG_QTY (REGNO (src)); 5598 struct qty_table_elem *src_ent = &qty_table[src_q]; 5599 int first = src_ent->first_reg; 5600 rtx new_src 5601 = (first >= FIRST_PSEUDO_REGISTER 5602 ? regno_reg_rtx[first] : gen_rtx_REG (GET_MODE (src), first)); 5603 5604 /* We must use validate-change even for this, because this 5605 might be a special no-op instruction, suitable only to 5606 tag notes onto. */ 5607 if (validate_change (insn, &SET_SRC (sets[i].rtl), new_src, 0)) 5608 { 5609 src = new_src; 5610 /* If we had a constant that is cheaper than what we are now 5611 setting SRC to, use that constant. We ignored it when we 5612 thought we could make this into a no-op. */ 5613 if (src_const && COST (src_const) < COST (src) 5614 && validate_change (insn, &SET_SRC (sets[i].rtl), 5615 src_const, 0)) 5616 src = src_const; 5617 } 5618 } 5619 } 5620 5621 /* If we made a change, recompute SRC values. */ 5622 if (src != sets[i].src) 5623 { 5624 cse_altered = 1; 5625 do_not_record = 0; 5626 hash_arg_in_memory = 0; 5627 sets[i].src = src; 5628 sets[i].src_hash = HASH (src, mode); 5629 sets[i].src_volatile = do_not_record; 5630 sets[i].src_in_memory = hash_arg_in_memory; 5631 sets[i].src_elt = lookup (src, sets[i].src_hash, mode); 5632 } 5633 5634 /* If this is a single SET, we are setting a register, and we have an 5635 equivalent constant, we want to add a REG_NOTE. We don't want 5636 to write a REG_EQUAL note for a constant pseudo since verifying that 5637 that pseudo hasn't been eliminated is a pain. Such a note also 5638 won't help anything. 5639 5640 Avoid a REG_EQUAL note for (CONST (MINUS (LABEL_REF) (LABEL_REF))) 5641 which can be created for a reference to a compile time computable 5642 entry in a jump table. */ 5643 5644 if (n_sets == 1 && src_const && GET_CODE (dest) == REG 5645 && GET_CODE (src_const) != REG 5646 && ! (GET_CODE (src_const) == CONST 5647 && GET_CODE (XEXP (src_const, 0)) == MINUS 5648 && GET_CODE (XEXP (XEXP (src_const, 0), 0)) == LABEL_REF 5649 && GET_CODE (XEXP (XEXP (src_const, 0), 1)) == LABEL_REF)) 5650 { 5651 /* Make sure that the rtx is not shared with any other insn. */ 5652 src_const = copy_rtx (src_const); 5653 5654 /* Record the actual constant value in a REG_EQUAL note, making 5655 a new one if one does not already exist. */ 5656 set_unique_reg_note (insn, REG_EQUAL, src_const); 5657 5658 /* If storing a constant value in a register that 5659 previously held the constant value 0, 5660 record this fact with a REG_WAS_0 note on this insn. 5661 5662 Note that the *register* is required to have previously held 0, 5663 not just any register in the quantity and we must point to the 5664 insn that set that register to zero. 5665 5666 Rather than track each register individually, we just see if 5667 the last set for this quantity was for this register. */ 5668 5669 if (REGNO_QTY_VALID_P (REGNO (dest))) 5670 { 5671 int dest_q = REG_QTY (REGNO (dest)); 5672 struct qty_table_elem *dest_ent = &qty_table[dest_q]; 5673 5674 if (dest_ent->const_rtx == const0_rtx) 5675 { 5676 /* See if we previously had a REG_WAS_0 note. */ 5677 rtx note = find_reg_note (insn, REG_WAS_0, NULL_RTX); 5678 rtx const_insn = dest_ent->const_insn; 5679 5680 if ((tem = single_set (const_insn)) != 0 5681 && rtx_equal_p (SET_DEST (tem), dest)) 5682 { 5683 if (note) 5684 XEXP (note, 0) = const_insn; 5685 else 5686 REG_NOTES (insn) 5687 = gen_rtx_INSN_LIST (REG_WAS_0, const_insn, 5688 REG_NOTES (insn)); 5689 } 5690 } 5691 } 5692 } 5693 5694 /* Now deal with the destination. */ 5695 do_not_record = 0; 5696 5697 /* Look within any SIGN_EXTRACT or ZERO_EXTRACT 5698 to the MEM or REG within it. */ 5699 while (GET_CODE (dest) == SIGN_EXTRACT 5700 || GET_CODE (dest) == ZERO_EXTRACT 5701 || GET_CODE (dest) == SUBREG 5702 || GET_CODE (dest) == STRICT_LOW_PART) 5703 dest = XEXP (dest, 0); 5704 5705 sets[i].inner_dest = dest; 5706 5707 if (GET_CODE (dest) == MEM) 5708 { 5709#ifdef PUSH_ROUNDING 5710 /* Stack pushes invalidate the stack pointer. */ 5711 rtx addr = XEXP (dest, 0); 5712 if (GET_RTX_CLASS (GET_CODE (addr)) == 'a' 5713 && XEXP (addr, 0) == stack_pointer_rtx) 5714 invalidate (stack_pointer_rtx, Pmode); 5715#endif 5716 dest = fold_rtx (dest, insn); 5717 } 5718 5719 /* Compute the hash code of the destination now, 5720 before the effects of this instruction are recorded, 5721 since the register values used in the address computation 5722 are those before this instruction. */ 5723 sets[i].dest_hash = HASH (dest, mode); 5724 5725 /* Don't enter a bit-field in the hash table 5726 because the value in it after the store 5727 may not equal what was stored, due to truncation. */ 5728 5729 if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT 5730 || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT) 5731 { 5732 rtx width = XEXP (SET_DEST (sets[i].rtl), 1); 5733 5734 if (src_const != 0 && GET_CODE (src_const) == CONST_INT 5735 && GET_CODE (width) == CONST_INT 5736 && INTVAL (width) < HOST_BITS_PER_WIDE_INT 5737 && ! (INTVAL (src_const) 5738 & ((HOST_WIDE_INT) (-1) << INTVAL (width)))) 5739 /* Exception: if the value is constant, 5740 and it won't be truncated, record it. */ 5741 ; 5742 else 5743 { 5744 /* This is chosen so that the destination will be invalidated 5745 but no new value will be recorded. 5746 We must invalidate because sometimes constant 5747 values can be recorded for bitfields. */ 5748 sets[i].src_elt = 0; 5749 sets[i].src_volatile = 1; 5750 src_eqv = 0; 5751 src_eqv_elt = 0; 5752 } 5753 } 5754 5755 /* If only one set in a JUMP_INSN and it is now a no-op, we can delete 5756 the insn. */ 5757 else if (n_sets == 1 && dest == pc_rtx && src == pc_rtx) 5758 { 5759 /* One less use of the label this insn used to jump to. */ 5760 delete_insn (insn); 5761 cse_jumps_altered = 1; 5762 /* No more processing for this set. */ 5763 sets[i].rtl = 0; 5764 } 5765 5766 /* If this SET is now setting PC to a label, we know it used to 5767 be a conditional or computed branch. */ 5768 else if (dest == pc_rtx && GET_CODE (src) == LABEL_REF) 5769 { 5770 /* Now emit a BARRIER after the unconditional jump. */ 5771 if (NEXT_INSN (insn) == 0 5772 || GET_CODE (NEXT_INSN (insn)) != BARRIER) 5773 emit_barrier_after (insn); 5774 5775 /* We reemit the jump in as many cases as possible just in 5776 case the form of an unconditional jump is significantly 5777 different than a computed jump or conditional jump. 5778 5779 If this insn has multiple sets, then reemitting the 5780 jump is nontrivial. So instead we just force rerecognition 5781 and hope for the best. */ 5782 if (n_sets == 1) 5783 { 5784 rtx new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn); 5785 5786 JUMP_LABEL (new) = XEXP (src, 0); 5787 LABEL_NUSES (XEXP (src, 0))++; 5788 insn = new; 5789 5790 /* Now emit a BARRIER after the unconditional jump. */ 5791 if (NEXT_INSN (insn) == 0 5792 || GET_CODE (NEXT_INSN (insn)) != BARRIER) 5793 emit_barrier_after (insn); 5794 } 5795 else 5796 INSN_CODE (insn) = -1; 5797 5798 never_reached_warning (insn); 5799 5800 /* Do not bother deleting any unreachable code, 5801 let jump/flow do that. */ 5802 5803 cse_jumps_altered = 1; 5804 sets[i].rtl = 0; 5805 } 5806 5807 /* If destination is volatile, invalidate it and then do no further 5808 processing for this assignment. */ 5809 5810 else if (do_not_record) 5811 { 5812 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG) 5813 invalidate (dest, VOIDmode); 5814 else if (GET_CODE (dest) == MEM) 5815 { 5816 /* Outgoing arguments for a libcall don't 5817 affect any recorded expressions. */ 5818 if (! libcall_insn || insn == libcall_insn) 5819 invalidate (dest, VOIDmode); 5820 } 5821 else if (GET_CODE (dest) == STRICT_LOW_PART 5822 || GET_CODE (dest) == ZERO_EXTRACT) 5823 invalidate (XEXP (dest, 0), GET_MODE (dest)); 5824 sets[i].rtl = 0; 5825 } 5826 5827 if (sets[i].rtl != 0 && dest != SET_DEST (sets[i].rtl)) 5828 sets[i].dest_hash = HASH (SET_DEST (sets[i].rtl), mode); 5829 5830#ifdef HAVE_cc0 5831 /* If setting CC0, record what it was set to, or a constant, if it 5832 is equivalent to a constant. If it is being set to a floating-point 5833 value, make a COMPARE with the appropriate constant of 0. If we 5834 don't do this, later code can interpret this as a test against 5835 const0_rtx, which can cause problems if we try to put it into an 5836 insn as a floating-point operand. */ 5837 if (dest == cc0_rtx) 5838 { 5839 this_insn_cc0 = src_const && mode != VOIDmode ? src_const : src; 5840 this_insn_cc0_mode = mode; 5841 if (FLOAT_MODE_P (mode)) 5842 this_insn_cc0 = gen_rtx_COMPARE (VOIDmode, this_insn_cc0, 5843 CONST0_RTX (mode)); 5844 } 5845#endif 5846 } 5847 5848 /* Now enter all non-volatile source expressions in the hash table 5849 if they are not already present. 5850 Record their equivalence classes in src_elt. 5851 This way we can insert the corresponding destinations into 5852 the same classes even if the actual sources are no longer in them 5853 (having been invalidated). */ 5854 5855 if (src_eqv && src_eqv_elt == 0 && sets[0].rtl != 0 && ! src_eqv_volatile 5856 && ! rtx_equal_p (src_eqv, SET_DEST (sets[0].rtl))) 5857 { 5858 struct table_elt *elt; 5859 struct table_elt *classp = sets[0].src_elt; 5860 rtx dest = SET_DEST (sets[0].rtl); 5861 enum machine_mode eqvmode = GET_MODE (dest); 5862 5863 if (GET_CODE (dest) == STRICT_LOW_PART) 5864 { 5865 eqvmode = GET_MODE (SUBREG_REG (XEXP (dest, 0))); 5866 classp = 0; 5867 } 5868 if (insert_regs (src_eqv, classp, 0)) 5869 { 5870 rehash_using_reg (src_eqv); 5871 src_eqv_hash = HASH (src_eqv, eqvmode); 5872 } 5873 elt = insert (src_eqv, classp, src_eqv_hash, eqvmode); 5874 elt->in_memory = src_eqv_in_memory; 5875 src_eqv_elt = elt; 5876 5877 /* Check to see if src_eqv_elt is the same as a set source which 5878 does not yet have an elt, and if so set the elt of the set source 5879 to src_eqv_elt. */ 5880 for (i = 0; i < n_sets; i++) 5881 if (sets[i].rtl && sets[i].src_elt == 0 5882 && rtx_equal_p (SET_SRC (sets[i].rtl), src_eqv)) 5883 sets[i].src_elt = src_eqv_elt; 5884 } 5885 5886 for (i = 0; i < n_sets; i++) 5887 if (sets[i].rtl && ! sets[i].src_volatile 5888 && ! rtx_equal_p (SET_SRC (sets[i].rtl), SET_DEST (sets[i].rtl))) 5889 { 5890 if (GET_CODE (SET_DEST (sets[i].rtl)) == STRICT_LOW_PART) 5891 { 5892 /* REG_EQUAL in setting a STRICT_LOW_PART 5893 gives an equivalent for the entire destination register, 5894 not just for the subreg being stored in now. 5895 This is a more interesting equivalence, so we arrange later 5896 to treat the entire reg as the destination. */ 5897 sets[i].src_elt = src_eqv_elt; 5898 sets[i].src_hash = src_eqv_hash; 5899 } 5900 else 5901 { 5902 /* Insert source and constant equivalent into hash table, if not 5903 already present. */ 5904 struct table_elt *classp = src_eqv_elt; 5905 rtx src = sets[i].src; 5906 rtx dest = SET_DEST (sets[i].rtl); 5907 enum machine_mode mode 5908 = GET_MODE (src) == VOIDmode ? GET_MODE (dest) : GET_MODE (src); 5909 5910 if (sets[i].src_elt == 0) 5911 { 5912 /* Don't put a hard register source into the table if this is 5913 the last insn of a libcall. In this case, we only need 5914 to put src_eqv_elt in src_elt. */ 5915 if (! find_reg_note (insn, REG_RETVAL, NULL_RTX)) 5916 { 5917 struct table_elt *elt; 5918 5919 /* Note that these insert_regs calls cannot remove 5920 any of the src_elt's, because they would have failed to 5921 match if not still valid. */ 5922 if (insert_regs (src, classp, 0)) 5923 { 5924 rehash_using_reg (src); 5925 sets[i].src_hash = HASH (src, mode); 5926 } 5927 elt = insert (src, classp, sets[i].src_hash, mode); 5928 elt->in_memory = sets[i].src_in_memory; 5929 sets[i].src_elt = classp = elt; 5930 } 5931 else 5932 sets[i].src_elt = classp; 5933 } 5934 if (sets[i].src_const && sets[i].src_const_elt == 0 5935 && src != sets[i].src_const 5936 && ! rtx_equal_p (sets[i].src_const, src)) 5937 sets[i].src_elt = insert (sets[i].src_const, classp, 5938 sets[i].src_const_hash, mode); 5939 } 5940 } 5941 else if (sets[i].src_elt == 0) 5942 /* If we did not insert the source into the hash table (e.g., it was 5943 volatile), note the equivalence class for the REG_EQUAL value, if any, 5944 so that the destination goes into that class. */ 5945 sets[i].src_elt = src_eqv_elt; 5946 5947 invalidate_from_clobbers (x); 5948 5949 /* Some registers are invalidated by subroutine calls. Memory is 5950 invalidated by non-constant calls. */ 5951 5952 if (GET_CODE (insn) == CALL_INSN) 5953 { 5954 if (! CONST_OR_PURE_CALL_P (insn)) 5955 invalidate_memory (); 5956 invalidate_for_call (); 5957 } 5958 5959 /* Now invalidate everything set by this instruction. 5960 If a SUBREG or other funny destination is being set, 5961 sets[i].rtl is still nonzero, so here we invalidate the reg 5962 a part of which is being set. */ 5963 5964 for (i = 0; i < n_sets; i++) 5965 if (sets[i].rtl) 5966 { 5967 /* We can't use the inner dest, because the mode associated with 5968 a ZERO_EXTRACT is significant. */ 5969 rtx dest = SET_DEST (sets[i].rtl); 5970 5971 /* Needed for registers to remove the register from its 5972 previous quantity's chain. 5973 Needed for memory if this is a nonvarying address, unless 5974 we have just done an invalidate_memory that covers even those. */ 5975 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG) 5976 invalidate (dest, VOIDmode); 5977 else if (GET_CODE (dest) == MEM) 5978 { 5979 /* Outgoing arguments for a libcall don't 5980 affect any recorded expressions. */ 5981 if (! libcall_insn || insn == libcall_insn) 5982 invalidate (dest, VOIDmode); 5983 } 5984 else if (GET_CODE (dest) == STRICT_LOW_PART 5985 || GET_CODE (dest) == ZERO_EXTRACT) 5986 invalidate (XEXP (dest, 0), GET_MODE (dest)); 5987 } 5988 5989 /* A volatile ASM invalidates everything. */ 5990 if (GET_CODE (insn) == INSN 5991 && GET_CODE (PATTERN (insn)) == ASM_OPERANDS 5992 && MEM_VOLATILE_P (PATTERN (insn))) 5993 flush_hash_table (); 5994 5995 /* Make sure registers mentioned in destinations 5996 are safe for use in an expression to be inserted. 5997 This removes from the hash table 5998 any invalid entry that refers to one of these registers. 5999 6000 We don't care about the return value from mention_regs because 6001 we are going to hash the SET_DEST values unconditionally. */ 6002 6003 for (i = 0; i < n_sets; i++) 6004 { 6005 if (sets[i].rtl) 6006 { 6007 rtx x = SET_DEST (sets[i].rtl); 6008 6009 if (GET_CODE (x) != REG) 6010 mention_regs (x); 6011 else 6012 { 6013 /* We used to rely on all references to a register becoming 6014 inaccessible when a register changes to a new quantity, 6015 since that changes the hash code. However, that is not 6016 safe, since after HASH_SIZE new quantities we get a 6017 hash 'collision' of a register with its own invalid 6018 entries. And since SUBREGs have been changed not to 6019 change their hash code with the hash code of the register, 6020 it wouldn't work any longer at all. So we have to check 6021 for any invalid references lying around now. 6022 This code is similar to the REG case in mention_regs, 6023 but it knows that reg_tick has been incremented, and 6024 it leaves reg_in_table as -1 . */ 6025 unsigned int regno = REGNO (x); 6026 unsigned int endregno 6027 = regno + (regno >= FIRST_PSEUDO_REGISTER ? 1 6028 : HARD_REGNO_NREGS (regno, GET_MODE (x))); 6029 unsigned int i; 6030 6031 for (i = regno; i < endregno; i++) 6032 { 6033 if (REG_IN_TABLE (i) >= 0) 6034 { 6035 remove_invalid_refs (i); 6036 REG_IN_TABLE (i) = -1; 6037 } 6038 } 6039 } 6040 } 6041 } 6042 6043 /* We may have just removed some of the src_elt's from the hash table. 6044 So replace each one with the current head of the same class. */ 6045 6046 for (i = 0; i < n_sets; i++) 6047 if (sets[i].rtl) 6048 { 6049 if (sets[i].src_elt && sets[i].src_elt->first_same_value == 0) 6050 /* If elt was removed, find current head of same class, 6051 or 0 if nothing remains of that class. */ 6052 { 6053 struct table_elt *elt = sets[i].src_elt; 6054 6055 while (elt && elt->prev_same_value) 6056 elt = elt->prev_same_value; 6057 6058 while (elt && elt->first_same_value == 0) 6059 elt = elt->next_same_value; 6060 sets[i].src_elt = elt ? elt->first_same_value : 0; 6061 } 6062 } 6063 6064 /* Now insert the destinations into their equivalence classes. */ 6065 6066 for (i = 0; i < n_sets; i++) 6067 if (sets[i].rtl) 6068 { 6069 rtx dest = SET_DEST (sets[i].rtl); 6070 rtx inner_dest = sets[i].inner_dest; 6071 struct table_elt *elt; 6072 6073 /* Don't record value if we are not supposed to risk allocating 6074 floating-point values in registers that might be wider than 6075 memory. */ 6076 if ((flag_float_store 6077 && GET_CODE (dest) == MEM 6078 && FLOAT_MODE_P (GET_MODE (dest))) 6079 /* Don't record BLKmode values, because we don't know the 6080 size of it, and can't be sure that other BLKmode values 6081 have the same or smaller size. */ 6082 || GET_MODE (dest) == BLKmode 6083 /* Don't record values of destinations set inside a libcall block 6084 since we might delete the libcall. Things should have been set 6085 up so we won't want to reuse such a value, but we play it safe 6086 here. */ 6087 || libcall_insn 6088 /* If we didn't put a REG_EQUAL value or a source into the hash 6089 table, there is no point is recording DEST. */ 6090 || sets[i].src_elt == 0 6091 /* If DEST is a paradoxical SUBREG and SRC is a ZERO_EXTEND 6092 or SIGN_EXTEND, don't record DEST since it can cause 6093 some tracking to be wrong. 6094 6095 ??? Think about this more later. */ 6096 || (GET_CODE (dest) == SUBREG 6097 && (GET_MODE_SIZE (GET_MODE (dest)) 6098 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest)))) 6099 && (GET_CODE (sets[i].src) == SIGN_EXTEND 6100 || GET_CODE (sets[i].src) == ZERO_EXTEND))) 6101 continue; 6102 6103 /* STRICT_LOW_PART isn't part of the value BEING set, 6104 and neither is the SUBREG inside it. 6105 Note that in this case SETS[I].SRC_ELT is really SRC_EQV_ELT. */ 6106 if (GET_CODE (dest) == STRICT_LOW_PART) 6107 dest = SUBREG_REG (XEXP (dest, 0)); 6108 6109 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG) 6110 /* Registers must also be inserted into chains for quantities. */ 6111 if (insert_regs (dest, sets[i].src_elt, 1)) 6112 { 6113 /* If `insert_regs' changes something, the hash code must be 6114 recalculated. */ 6115 rehash_using_reg (dest); 6116 sets[i].dest_hash = HASH (dest, GET_MODE (dest)); 6117 } 6118 6119 if (GET_CODE (inner_dest) == MEM 6120 && GET_CODE (XEXP (inner_dest, 0)) == ADDRESSOF) 6121 /* Given (SET (MEM (ADDRESSOF (X))) Y) we don't want to say 6122 that (MEM (ADDRESSOF (X))) is equivalent to Y. 6123 Consider the case in which the address of the MEM is 6124 passed to a function, which alters the MEM. Then, if we 6125 later use Y instead of the MEM we'll miss the update. */ 6126 elt = insert (dest, 0, sets[i].dest_hash, GET_MODE (dest)); 6127 else 6128 elt = insert (dest, sets[i].src_elt, 6129 sets[i].dest_hash, GET_MODE (dest)); 6130 6131 elt->in_memory = (GET_CODE (sets[i].inner_dest) == MEM 6132 && (! RTX_UNCHANGING_P (sets[i].inner_dest) 6133 || FIXED_BASE_PLUS_P (XEXP (sets[i].inner_dest, 6134 0)))); 6135 6136 /* If we have (set (subreg:m1 (reg:m2 foo) 0) (bar:m1)), M1 is no 6137 narrower than M2, and both M1 and M2 are the same number of words, 6138 we are also doing (set (reg:m2 foo) (subreg:m2 (bar:m1) 0)) so 6139 make that equivalence as well. 6140 6141 However, BAR may have equivalences for which gen_lowpart_if_possible 6142 will produce a simpler value than gen_lowpart_if_possible applied to 6143 BAR (e.g., if BAR was ZERO_EXTENDed from M2), so we will scan all 6144 BAR's equivalences. If we don't get a simplified form, make 6145 the SUBREG. It will not be used in an equivalence, but will 6146 cause two similar assignments to be detected. 6147 6148 Note the loop below will find SUBREG_REG (DEST) since we have 6149 already entered SRC and DEST of the SET in the table. */ 6150 6151 if (GET_CODE (dest) == SUBREG 6152 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))) - 1) 6153 / UNITS_PER_WORD) 6154 == (GET_MODE_SIZE (GET_MODE (dest)) - 1) / UNITS_PER_WORD) 6155 && (GET_MODE_SIZE (GET_MODE (dest)) 6156 >= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest)))) 6157 && sets[i].src_elt != 0) 6158 { 6159 enum machine_mode new_mode = GET_MODE (SUBREG_REG (dest)); 6160 struct table_elt *elt, *classp = 0; 6161 6162 for (elt = sets[i].src_elt->first_same_value; elt; 6163 elt = elt->next_same_value) 6164 { 6165 rtx new_src = 0; 6166 unsigned src_hash; 6167 struct table_elt *src_elt; 6168 6169 /* Ignore invalid entries. */ 6170 if (GET_CODE (elt->exp) != REG 6171 && ! exp_equiv_p (elt->exp, elt->exp, 1, 0)) 6172 continue; 6173 6174 new_src = gen_lowpart_if_possible (new_mode, elt->exp); 6175 if (new_src == 0) 6176 new_src = gen_rtx_SUBREG (new_mode, elt->exp, 0); 6177 6178 src_hash = HASH (new_src, new_mode); 6179 src_elt = lookup (new_src, src_hash, new_mode); 6180 6181 /* Put the new source in the hash table is if isn't 6182 already. */ 6183 if (src_elt == 0) 6184 { 6185 if (insert_regs (new_src, classp, 0)) 6186 { 6187 rehash_using_reg (new_src); 6188 src_hash = HASH (new_src, new_mode); 6189 } 6190 src_elt = insert (new_src, classp, src_hash, new_mode); 6191 src_elt->in_memory = elt->in_memory; 6192 } 6193 else if (classp && classp != src_elt->first_same_value) 6194 /* Show that two things that we've seen before are 6195 actually the same. */ 6196 merge_equiv_classes (src_elt, classp); 6197 6198 classp = src_elt->first_same_value; 6199 /* Ignore invalid entries. */ 6200 while (classp 6201 && GET_CODE (classp->exp) != REG 6202 && ! exp_equiv_p (classp->exp, classp->exp, 1, 0)) 6203 classp = classp->next_same_value; 6204 } 6205 } 6206 } 6207 6208 /* Special handling for (set REG0 REG1) where REG0 is the 6209 "cheapest", cheaper than REG1. After cse, REG1 will probably not 6210 be used in the sequel, so (if easily done) change this insn to 6211 (set REG1 REG0) and replace REG1 with REG0 in the previous insn 6212 that computed their value. Then REG1 will become a dead store 6213 and won't cloud the situation for later optimizations. 6214 6215 Do not make this change if REG1 is a hard register, because it will 6216 then be used in the sequel and we may be changing a two-operand insn 6217 into a three-operand insn. 6218 6219 Also do not do this if we are operating on a copy of INSN. 6220 6221 Also don't do this if INSN ends a libcall; this would cause an unrelated 6222 register to be set in the middle of a libcall, and we then get bad code 6223 if the libcall is deleted. */ 6224 6225 if (n_sets == 1 && sets[0].rtl && GET_CODE (SET_DEST (sets[0].rtl)) == REG 6226 && NEXT_INSN (PREV_INSN (insn)) == insn 6227 && GET_CODE (SET_SRC (sets[0].rtl)) == REG 6228 && REGNO (SET_SRC (sets[0].rtl)) >= FIRST_PSEUDO_REGISTER 6229 && REGNO_QTY_VALID_P (REGNO (SET_SRC (sets[0].rtl)))) 6230 { 6231 int src_q = REG_QTY (REGNO (SET_SRC (sets[0].rtl))); 6232 struct qty_table_elem *src_ent = &qty_table[src_q]; 6233 6234 if ((src_ent->first_reg == REGNO (SET_DEST (sets[0].rtl))) 6235 && ! find_reg_note (insn, REG_RETVAL, NULL_RTX)) 6236 { 6237 rtx prev = prev_nonnote_insn (insn); 6238 6239 /* Do not swap the registers around if the previous instruction 6240 attaches a REG_EQUIV note to REG1. 6241 6242 ??? It's not entirely clear whether we can transfer a REG_EQUIV 6243 from the pseudo that originally shadowed an incoming argument 6244 to another register. Some uses of REG_EQUIV might rely on it 6245 being attached to REG1 rather than REG2. 6246 6247 This section previously turned the REG_EQUIV into a REG_EQUAL 6248 note. We cannot do that because REG_EQUIV may provide an 6249 uninitialised stack slot when REG_PARM_STACK_SPACE is used. */ 6250 6251 if (prev != 0 && GET_CODE (prev) == INSN 6252 && GET_CODE (PATTERN (prev)) == SET 6253 && SET_DEST (PATTERN (prev)) == SET_SRC (sets[0].rtl) 6254 && ! find_reg_note (prev, REG_EQUIV, NULL_RTX)) 6255 { 6256 rtx dest = SET_DEST (sets[0].rtl); 6257 rtx src = SET_SRC (sets[0].rtl); 6258 rtx note; 6259 6260 validate_change (prev, &SET_DEST (PATTERN (prev)), dest, 1); 6261 validate_change (insn, &SET_DEST (sets[0].rtl), src, 1); 6262 validate_change (insn, &SET_SRC (sets[0].rtl), dest, 1); 6263 apply_change_group (); 6264 6265 /* If there was a REG_WAS_0 note on PREV, remove it. Move 6266 any REG_WAS_0 note on INSN to PREV. */ 6267 note = find_reg_note (prev, REG_WAS_0, NULL_RTX); 6268 if (note) 6269 remove_note (prev, note); 6270 6271 note = find_reg_note (insn, REG_WAS_0, NULL_RTX); 6272 if (note) 6273 { 6274 remove_note (insn, note); 6275 XEXP (note, 1) = REG_NOTES (prev); 6276 REG_NOTES (prev) = note; 6277 } 6278 6279 /* If INSN has a REG_EQUAL note, and this note mentions 6280 REG0, then we must delete it, because the value in 6281 REG0 has changed. If the note's value is REG1, we must 6282 also delete it because that is now this insn's dest. */ 6283 note = find_reg_note (insn, REG_EQUAL, NULL_RTX); 6284 if (note != 0 6285 && (reg_mentioned_p (dest, XEXP (note, 0)) 6286 || rtx_equal_p (src, XEXP (note, 0)))) 6287 remove_note (insn, note); 6288 } 6289 } 6290 } 6291 6292 /* If this is a conditional jump insn, record any known equivalences due to 6293 the condition being tested. */ 6294 6295 last_jump_equiv_class = 0; 6296 if (GET_CODE (insn) == JUMP_INSN 6297 && n_sets == 1 && GET_CODE (x) == SET 6298 && GET_CODE (SET_SRC (x)) == IF_THEN_ELSE) 6299 record_jump_equiv (insn, 0); 6300 6301#ifdef HAVE_cc0 6302 /* If the previous insn set CC0 and this insn no longer references CC0, 6303 delete the previous insn. Here we use the fact that nothing expects CC0 6304 to be valid over an insn, which is true until the final pass. */ 6305 if (prev_insn && GET_CODE (prev_insn) == INSN 6306 && (tem = single_set (prev_insn)) != 0 6307 && SET_DEST (tem) == cc0_rtx 6308 && ! reg_mentioned_p (cc0_rtx, x)) 6309 delete_insn (prev_insn); 6310 6311 prev_insn_cc0 = this_insn_cc0; 6312 prev_insn_cc0_mode = this_insn_cc0_mode; 6313#endif 6314 6315 prev_insn = insn; 6316} 6317 6318/* Remove from the hash table all expressions that reference memory. */ 6319 6320static void 6321invalidate_memory () 6322{ 6323 int i; 6324 struct table_elt *p, *next; 6325 6326 for (i = 0; i < HASH_SIZE; i++) 6327 for (p = table[i]; p; p = next) 6328 { 6329 next = p->next_same_hash; 6330 if (p->in_memory) 6331 remove_from_table (p, i); 6332 } 6333} 6334 6335/* If ADDR is an address that implicitly affects the stack pointer, return 6336 1 and update the register tables to show the effect. Else, return 0. */ 6337 6338static int 6339addr_affects_sp_p (addr) 6340 rtx addr; 6341{ 6342 if (GET_RTX_CLASS (GET_CODE (addr)) == 'a' 6343 && GET_CODE (XEXP (addr, 0)) == REG 6344 && REGNO (XEXP (addr, 0)) == STACK_POINTER_REGNUM) 6345 { 6346 if (REG_TICK (STACK_POINTER_REGNUM) >= 0) 6347 REG_TICK (STACK_POINTER_REGNUM)++; 6348 6349 /* This should be *very* rare. */ 6350 if (TEST_HARD_REG_BIT (hard_regs_in_table, STACK_POINTER_REGNUM)) 6351 invalidate (stack_pointer_rtx, VOIDmode); 6352 6353 return 1; 6354 } 6355 6356 return 0; 6357} 6358 6359/* Perform invalidation on the basis of everything about an insn 6360 except for invalidating the actual places that are SET in it. 6361 This includes the places CLOBBERed, and anything that might 6362 alias with something that is SET or CLOBBERed. 6363 6364 X is the pattern of the insn. */ 6365 6366static void 6367invalidate_from_clobbers (x) 6368 rtx x; 6369{ 6370 if (GET_CODE (x) == CLOBBER) 6371 { 6372 rtx ref = XEXP (x, 0); 6373 if (ref) 6374 { 6375 if (GET_CODE (ref) == REG || GET_CODE (ref) == SUBREG 6376 || GET_CODE (ref) == MEM) 6377 invalidate (ref, VOIDmode); 6378 else if (GET_CODE (ref) == STRICT_LOW_PART 6379 || GET_CODE (ref) == ZERO_EXTRACT) 6380 invalidate (XEXP (ref, 0), GET_MODE (ref)); 6381 } 6382 } 6383 else if (GET_CODE (x) == PARALLEL) 6384 { 6385 int i; 6386 for (i = XVECLEN (x, 0) - 1; i >= 0; i--) 6387 { 6388 rtx y = XVECEXP (x, 0, i); 6389 if (GET_CODE (y) == CLOBBER) 6390 { 6391 rtx ref = XEXP (y, 0); 6392 if (GET_CODE (ref) == REG || GET_CODE (ref) == SUBREG 6393 || GET_CODE (ref) == MEM) 6394 invalidate (ref, VOIDmode); 6395 else if (GET_CODE (ref) == STRICT_LOW_PART 6396 || GET_CODE (ref) == ZERO_EXTRACT) 6397 invalidate (XEXP (ref, 0), GET_MODE (ref)); 6398 } 6399 } 6400 } 6401} 6402 6403/* Process X, part of the REG_NOTES of an insn. Look at any REG_EQUAL notes 6404 and replace any registers in them with either an equivalent constant 6405 or the canonical form of the register. If we are inside an address, 6406 only do this if the address remains valid. 6407 6408 OBJECT is 0 except when within a MEM in which case it is the MEM. 6409 6410 Return the replacement for X. */ 6411 6412static rtx 6413cse_process_notes (x, object) 6414 rtx x; 6415 rtx object; 6416{ 6417 enum rtx_code code = GET_CODE (x); 6418 const char *fmt = GET_RTX_FORMAT (code); 6419 int i; 6420 6421 switch (code) 6422 { 6423 case CONST_INT: 6424 case CONST: 6425 case SYMBOL_REF: 6426 case LABEL_REF: 6427 case CONST_DOUBLE: 6428 case PC: 6429 case CC0: 6430 case LO_SUM: 6431 return x; 6432 6433 case MEM: 6434 validate_change (x, &XEXP (x, 0), 6435 cse_process_notes (XEXP (x, 0), x), 0); 6436 return x; 6437 6438 case EXPR_LIST: 6439 case INSN_LIST: 6440 if (REG_NOTE_KIND (x) == REG_EQUAL) 6441 XEXP (x, 0) = cse_process_notes (XEXP (x, 0), NULL_RTX); 6442 if (XEXP (x, 1)) 6443 XEXP (x, 1) = cse_process_notes (XEXP (x, 1), NULL_RTX); 6444 return x; 6445 6446 case SIGN_EXTEND: 6447 case ZERO_EXTEND: 6448 case SUBREG: 6449 { 6450 rtx new = cse_process_notes (XEXP (x, 0), object); 6451 /* We don't substitute VOIDmode constants into these rtx, 6452 since they would impede folding. */ 6453 if (GET_MODE (new) != VOIDmode) 6454 validate_change (object, &XEXP (x, 0), new, 0); 6455 return x; 6456 } 6457 6458 case REG: 6459 i = REG_QTY (REGNO (x)); 6460 6461 /* Return a constant or a constant register. */ 6462 if (REGNO_QTY_VALID_P (REGNO (x))) 6463 { 6464 struct qty_table_elem *ent = &qty_table[i]; 6465 6466 if (ent->const_rtx != NULL_RTX 6467 && (CONSTANT_P (ent->const_rtx) 6468 || GET_CODE (ent->const_rtx) == REG)) 6469 { 6470 rtx new = gen_lowpart_if_possible (GET_MODE (x), ent->const_rtx); 6471 if (new) 6472 return new; 6473 } 6474 } 6475 6476 /* Otherwise, canonicalize this register. */ 6477 return canon_reg (x, NULL_RTX); 6478 6479 default: 6480 break; 6481 } 6482 6483 for (i = 0; i < GET_RTX_LENGTH (code); i++) 6484 if (fmt[i] == 'e') 6485 validate_change (object, &XEXP (x, i), 6486 cse_process_notes (XEXP (x, i), object), 0); 6487 6488 return x; 6489} 6490 6491/* Find common subexpressions between the end test of a loop and the beginning 6492 of the loop. LOOP_START is the CODE_LABEL at the start of a loop. 6493 6494 Often we have a loop where an expression in the exit test is used 6495 in the body of the loop. For example "while (*p) *q++ = *p++;". 6496 Because of the way we duplicate the loop exit test in front of the loop, 6497 however, we don't detect that common subexpression. This will be caught 6498 when global cse is implemented, but this is a quite common case. 6499 6500 This function handles the most common cases of these common expressions. 6501 It is called after we have processed the basic block ending with the 6502 NOTE_INSN_LOOP_END note that ends a loop and the previous JUMP_INSN 6503 jumps to a label used only once. */ 6504 6505static void 6506cse_around_loop (loop_start) 6507 rtx loop_start; 6508{ 6509 rtx insn; 6510 int i; 6511 struct table_elt *p; 6512 6513 /* If the jump at the end of the loop doesn't go to the start, we don't 6514 do anything. */ 6515 for (insn = PREV_INSN (loop_start); 6516 insn && (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0); 6517 insn = PREV_INSN (insn)) 6518 ; 6519 6520 if (insn == 0 6521 || GET_CODE (insn) != NOTE 6522 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG) 6523 return; 6524 6525 /* If the last insn of the loop (the end test) was an NE comparison, 6526 we will interpret it as an EQ comparison, since we fell through 6527 the loop. Any equivalences resulting from that comparison are 6528 therefore not valid and must be invalidated. */ 6529 if (last_jump_equiv_class) 6530 for (p = last_jump_equiv_class->first_same_value; p; 6531 p = p->next_same_value) 6532 { 6533 if (GET_CODE (p->exp) == MEM || GET_CODE (p->exp) == REG 6534 || (GET_CODE (p->exp) == SUBREG 6535 && GET_CODE (SUBREG_REG (p->exp)) == REG)) 6536 invalidate (p->exp, VOIDmode); 6537 else if (GET_CODE (p->exp) == STRICT_LOW_PART 6538 || GET_CODE (p->exp) == ZERO_EXTRACT) 6539 invalidate (XEXP (p->exp, 0), GET_MODE (p->exp)); 6540 } 6541 6542 /* Process insns starting after LOOP_START until we hit a CALL_INSN or 6543 a CODE_LABEL (we could handle a CALL_INSN, but it isn't worth it). 6544 6545 The only thing we do with SET_DEST is invalidate entries, so we 6546 can safely process each SET in order. It is slightly less efficient 6547 to do so, but we only want to handle the most common cases. 6548 6549 The gen_move_insn call in cse_set_around_loop may create new pseudos. 6550 These pseudos won't have valid entries in any of the tables indexed 6551 by register number, such as reg_qty. We avoid out-of-range array 6552 accesses by not processing any instructions created after cse started. */ 6553 6554 for (insn = NEXT_INSN (loop_start); 6555 GET_CODE (insn) != CALL_INSN && GET_CODE (insn) != CODE_LABEL 6556 && INSN_UID (insn) < max_insn_uid 6557 && ! (GET_CODE (insn) == NOTE 6558 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END); 6559 insn = NEXT_INSN (insn)) 6560 { 6561 if (INSN_P (insn) 6562 && (GET_CODE (PATTERN (insn)) == SET 6563 || GET_CODE (PATTERN (insn)) == CLOBBER)) 6564 cse_set_around_loop (PATTERN (insn), insn, loop_start); 6565 else if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == PARALLEL) 6566 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--) 6567 if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == SET 6568 || GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER) 6569 cse_set_around_loop (XVECEXP (PATTERN (insn), 0, i), insn, 6570 loop_start); 6571 } 6572} 6573 6574/* Process one SET of an insn that was skipped. We ignore CLOBBERs 6575 since they are done elsewhere. This function is called via note_stores. */ 6576 6577static void 6578invalidate_skipped_set (dest, set, data) 6579 rtx set; 6580 rtx dest; 6581 void *data ATTRIBUTE_UNUSED; 6582{ 6583 enum rtx_code code = GET_CODE (dest); 6584 6585 if (code == MEM 6586 && ! addr_affects_sp_p (dest) /* If this is not a stack push ... */ 6587 /* There are times when an address can appear varying and be a PLUS 6588 during this scan when it would be a fixed address were we to know 6589 the proper equivalences. So invalidate all memory if there is 6590 a BLKmode or nonscalar memory reference or a reference to a 6591 variable address. */ 6592 && (MEM_IN_STRUCT_P (dest) || GET_MODE (dest) == BLKmode 6593 || cse_rtx_varies_p (XEXP (dest, 0), 0))) 6594 { 6595 invalidate_memory (); 6596 return; 6597 } 6598 6599 if (GET_CODE (set) == CLOBBER 6600#ifdef HAVE_cc0 6601 || dest == cc0_rtx 6602#endif 6603 || dest == pc_rtx) 6604 return; 6605 6606 if (code == STRICT_LOW_PART || code == ZERO_EXTRACT) 6607 invalidate (XEXP (dest, 0), GET_MODE (dest)); 6608 else if (code == REG || code == SUBREG || code == MEM) 6609 invalidate (dest, VOIDmode); 6610} 6611 6612/* Invalidate all insns from START up to the end of the function or the 6613 next label. This called when we wish to CSE around a block that is 6614 conditionally executed. */ 6615 6616static void 6617invalidate_skipped_block (start) 6618 rtx start; 6619{ 6620 rtx insn; 6621 6622 for (insn = start; insn && GET_CODE (insn) != CODE_LABEL; 6623 insn = NEXT_INSN (insn)) 6624 { 6625 if (! INSN_P (insn)) 6626 continue; 6627 6628 if (GET_CODE (insn) == CALL_INSN) 6629 { 6630 if (! CONST_OR_PURE_CALL_P (insn)) 6631 invalidate_memory (); 6632 invalidate_for_call (); 6633 } 6634 6635 invalidate_from_clobbers (PATTERN (insn)); 6636 note_stores (PATTERN (insn), invalidate_skipped_set, NULL); 6637 } 6638} 6639 6640/* If modifying X will modify the value in *DATA (which is really an 6641 `rtx *'), indicate that fact by setting the pointed to value to 6642 NULL_RTX. */ 6643 6644static void 6645cse_check_loop_start (x, set, data) 6646 rtx x; 6647 rtx set ATTRIBUTE_UNUSED; 6648 void *data; 6649{ 6650 rtx *cse_check_loop_start_value = (rtx *) data; 6651 6652 if (*cse_check_loop_start_value == NULL_RTX 6653 || GET_CODE (x) == CC0 || GET_CODE (x) == PC) 6654 return; 6655 6656 if ((GET_CODE (x) == MEM && GET_CODE (*cse_check_loop_start_value) == MEM) 6657 || reg_overlap_mentioned_p (x, *cse_check_loop_start_value)) 6658 *cse_check_loop_start_value = NULL_RTX; 6659} 6660 6661/* X is a SET or CLOBBER contained in INSN that was found near the start of 6662 a loop that starts with the label at LOOP_START. 6663 6664 If X is a SET, we see if its SET_SRC is currently in our hash table. 6665 If so, we see if it has a value equal to some register used only in the 6666 loop exit code (as marked by jump.c). 6667 6668 If those two conditions are true, we search backwards from the start of 6669 the loop to see if that same value was loaded into a register that still 6670 retains its value at the start of the loop. 6671 6672 If so, we insert an insn after the load to copy the destination of that 6673 load into the equivalent register and (try to) replace our SET_SRC with that 6674 register. 6675 6676 In any event, we invalidate whatever this SET or CLOBBER modifies. */ 6677 6678static void 6679cse_set_around_loop (x, insn, loop_start) 6680 rtx x; 6681 rtx insn; 6682 rtx loop_start; 6683{ 6684 struct table_elt *src_elt; 6685 6686 /* If this is a SET, see if we can replace SET_SRC, but ignore SETs that 6687 are setting PC or CC0 or whose SET_SRC is already a register. */ 6688 if (GET_CODE (x) == SET 6689 && GET_CODE (SET_DEST (x)) != PC && GET_CODE (SET_DEST (x)) != CC0 6690 && GET_CODE (SET_SRC (x)) != REG) 6691 { 6692 src_elt = lookup (SET_SRC (x), 6693 HASH (SET_SRC (x), GET_MODE (SET_DEST (x))), 6694 GET_MODE (SET_DEST (x))); 6695 6696 if (src_elt) 6697 for (src_elt = src_elt->first_same_value; src_elt; 6698 src_elt = src_elt->next_same_value) 6699 if (GET_CODE (src_elt->exp) == REG && REG_LOOP_TEST_P (src_elt->exp) 6700 && COST (src_elt->exp) < COST (SET_SRC (x))) 6701 { 6702 rtx p, set; 6703 6704 /* Look for an insn in front of LOOP_START that sets 6705 something in the desired mode to SET_SRC (x) before we hit 6706 a label or CALL_INSN. */ 6707 6708 for (p = prev_nonnote_insn (loop_start); 6709 p && GET_CODE (p) != CALL_INSN 6710 && GET_CODE (p) != CODE_LABEL; 6711 p = prev_nonnote_insn (p)) 6712 if ((set = single_set (p)) != 0 6713 && GET_CODE (SET_DEST (set)) == REG 6714 && GET_MODE (SET_DEST (set)) == src_elt->mode 6715 && rtx_equal_p (SET_SRC (set), SET_SRC (x))) 6716 { 6717 /* We now have to ensure that nothing between P 6718 and LOOP_START modified anything referenced in 6719 SET_SRC (x). We know that nothing within the loop 6720 can modify it, or we would have invalidated it in 6721 the hash table. */ 6722 rtx q; 6723 rtx cse_check_loop_start_value = SET_SRC (x); 6724 for (q = p; q != loop_start; q = NEXT_INSN (q)) 6725 if (INSN_P (q)) 6726 note_stores (PATTERN (q), 6727 cse_check_loop_start, 6728 &cse_check_loop_start_value); 6729 6730 /* If nothing was changed and we can replace our 6731 SET_SRC, add an insn after P to copy its destination 6732 to what we will be replacing SET_SRC with. */ 6733 if (cse_check_loop_start_value 6734 && validate_change (insn, &SET_SRC (x), 6735 src_elt->exp, 0)) 6736 { 6737 /* If this creates new pseudos, this is unsafe, 6738 because the regno of new pseudo is unsuitable 6739 to index into reg_qty when cse_insn processes 6740 the new insn. Therefore, if a new pseudo was 6741 created, discard this optimization. */ 6742 int nregs = max_reg_num (); 6743 rtx move 6744 = gen_move_insn (src_elt->exp, SET_DEST (set)); 6745 if (nregs != max_reg_num ()) 6746 { 6747 if (! validate_change (insn, &SET_SRC (x), 6748 SET_SRC (set), 0)) 6749 abort (); 6750 } 6751 else 6752 emit_insn_after (move, p); 6753 } 6754 break; 6755 } 6756 } 6757 } 6758 6759 /* Deal with the destination of X affecting the stack pointer. */ 6760 addr_affects_sp_p (SET_DEST (x)); 6761 6762 /* See comment on similar code in cse_insn for explanation of these 6763 tests. */ 6764 if (GET_CODE (SET_DEST (x)) == REG || GET_CODE (SET_DEST (x)) == SUBREG 6765 || GET_CODE (SET_DEST (x)) == MEM) 6766 invalidate (SET_DEST (x), VOIDmode); 6767 else if (GET_CODE (SET_DEST (x)) == STRICT_LOW_PART 6768 || GET_CODE (SET_DEST (x)) == ZERO_EXTRACT) 6769 invalidate (XEXP (SET_DEST (x), 0), GET_MODE (SET_DEST (x))); 6770} 6771 6772/* Find the end of INSN's basic block and return its range, 6773 the total number of SETs in all the insns of the block, the last insn of the 6774 block, and the branch path. 6775 6776 The branch path indicates which branches should be followed. If a non-zero 6777 path size is specified, the block should be rescanned and a different set 6778 of branches will be taken. The branch path is only used if 6779 FLAG_CSE_FOLLOW_JUMPS or FLAG_CSE_SKIP_BLOCKS is non-zero. 6780 6781 DATA is a pointer to a struct cse_basic_block_data, defined below, that is 6782 used to describe the block. It is filled in with the information about 6783 the current block. The incoming structure's branch path, if any, is used 6784 to construct the output branch path. */ 6785 6786void 6787cse_end_of_basic_block (insn, data, follow_jumps, after_loop, skip_blocks) 6788 rtx insn; 6789 struct cse_basic_block_data *data; 6790 int follow_jumps; 6791 int after_loop; 6792 int skip_blocks; 6793{ 6794 rtx p = insn, q; 6795 int nsets = 0; 6796 int low_cuid = INSN_CUID (insn), high_cuid = INSN_CUID (insn); 6797 rtx next = INSN_P (insn) ? insn : next_real_insn (insn); 6798 int path_size = data->path_size; 6799 int path_entry = 0; 6800 int i; 6801 6802 /* Update the previous branch path, if any. If the last branch was 6803 previously TAKEN, mark it NOT_TAKEN. If it was previously NOT_TAKEN, 6804 shorten the path by one and look at the previous branch. We know that 6805 at least one branch must have been taken if PATH_SIZE is non-zero. */ 6806 while (path_size > 0) 6807 { 6808 if (data->path[path_size - 1].status != NOT_TAKEN) 6809 { 6810 data->path[path_size - 1].status = NOT_TAKEN; 6811 break; 6812 } 6813 else 6814 path_size--; 6815 } 6816 6817 /* If the first instruction is marked with QImode, that means we've 6818 already processed this block. Our caller will look at DATA->LAST 6819 to figure out where to go next. We want to return the next block 6820 in the instruction stream, not some branched-to block somewhere 6821 else. We accomplish this by pretending our called forbid us to 6822 follow jumps, or skip blocks. */ 6823 if (GET_MODE (insn) == QImode) 6824 follow_jumps = skip_blocks = 0; 6825 6826 /* Scan to end of this basic block. */ 6827 while (p && GET_CODE (p) != CODE_LABEL) 6828 { 6829 /* Don't cse out the end of a loop. This makes a difference 6830 only for the unusual loops that always execute at least once; 6831 all other loops have labels there so we will stop in any case. 6832 Cse'ing out the end of the loop is dangerous because it 6833 might cause an invariant expression inside the loop 6834 to be reused after the end of the loop. This would make it 6835 hard to move the expression out of the loop in loop.c, 6836 especially if it is one of several equivalent expressions 6837 and loop.c would like to eliminate it. 6838 6839 If we are running after loop.c has finished, we can ignore 6840 the NOTE_INSN_LOOP_END. */ 6841 6842 if (! after_loop && GET_CODE (p) == NOTE 6843 && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END) 6844 break; 6845 6846 /* Don't cse over a call to setjmp; on some machines (eg VAX) 6847 the regs restored by the longjmp come from 6848 a later time than the setjmp. */ 6849 if (PREV_INSN (p) && GET_CODE (PREV_INSN (p)) == CALL_INSN 6850 && find_reg_note (PREV_INSN (p), REG_SETJMP, NULL)) 6851 break; 6852 6853 /* A PARALLEL can have lots of SETs in it, 6854 especially if it is really an ASM_OPERANDS. */ 6855 if (INSN_P (p) && GET_CODE (PATTERN (p)) == PARALLEL) 6856 nsets += XVECLEN (PATTERN (p), 0); 6857 else if (GET_CODE (p) != NOTE) 6858 nsets += 1; 6859 6860 /* Ignore insns made by CSE; they cannot affect the boundaries of 6861 the basic block. */ 6862 6863 if (INSN_UID (p) <= max_uid && INSN_CUID (p) > high_cuid) 6864 high_cuid = INSN_CUID (p); 6865 if (INSN_UID (p) <= max_uid && INSN_CUID (p) < low_cuid) 6866 low_cuid = INSN_CUID (p); 6867 6868 /* See if this insn is in our branch path. If it is and we are to 6869 take it, do so. */ 6870 if (path_entry < path_size && data->path[path_entry].branch == p) 6871 { 6872 if (data->path[path_entry].status != NOT_TAKEN) 6873 p = JUMP_LABEL (p); 6874 6875 /* Point to next entry in path, if any. */ 6876 path_entry++; 6877 } 6878 6879 /* If this is a conditional jump, we can follow it if -fcse-follow-jumps 6880 was specified, we haven't reached our maximum path length, there are 6881 insns following the target of the jump, this is the only use of the 6882 jump label, and the target label is preceded by a BARRIER. 6883 6884 Alternatively, we can follow the jump if it branches around a 6885 block of code and there are no other branches into the block. 6886 In this case invalidate_skipped_block will be called to invalidate any 6887 registers set in the block when following the jump. */ 6888 6889 else if ((follow_jumps || skip_blocks) && path_size < PATHLENGTH - 1 6890 && GET_CODE (p) == JUMP_INSN 6891 && GET_CODE (PATTERN (p)) == SET 6892 && GET_CODE (SET_SRC (PATTERN (p))) == IF_THEN_ELSE 6893 && JUMP_LABEL (p) != 0 6894 && LABEL_NUSES (JUMP_LABEL (p)) == 1 6895 && NEXT_INSN (JUMP_LABEL (p)) != 0) 6896 { 6897 for (q = PREV_INSN (JUMP_LABEL (p)); q; q = PREV_INSN (q)) 6898 if ((GET_CODE (q) != NOTE 6899 || NOTE_LINE_NUMBER (q) == NOTE_INSN_LOOP_END 6900 || (PREV_INSN (q) && GET_CODE (PREV_INSN (q)) == CALL_INSN 6901 && find_reg_note (PREV_INSN (q), REG_SETJMP, NULL))) 6902 && (GET_CODE (q) != CODE_LABEL || LABEL_NUSES (q) != 0)) 6903 break; 6904 6905 /* If we ran into a BARRIER, this code is an extension of the 6906 basic block when the branch is taken. */ 6907 if (follow_jumps && q != 0 && GET_CODE (q) == BARRIER) 6908 { 6909 /* Don't allow ourself to keep walking around an 6910 always-executed loop. */ 6911 if (next_real_insn (q) == next) 6912 { 6913 p = NEXT_INSN (p); 6914 continue; 6915 } 6916 6917 /* Similarly, don't put a branch in our path more than once. */ 6918 for (i = 0; i < path_entry; i++) 6919 if (data->path[i].branch == p) 6920 break; 6921 6922 if (i != path_entry) 6923 break; 6924 6925 data->path[path_entry].branch = p; 6926 data->path[path_entry++].status = TAKEN; 6927 6928 /* This branch now ends our path. It was possible that we 6929 didn't see this branch the last time around (when the 6930 insn in front of the target was a JUMP_INSN that was 6931 turned into a no-op). */ 6932 path_size = path_entry; 6933 6934 p = JUMP_LABEL (p); 6935 /* Mark block so we won't scan it again later. */ 6936 PUT_MODE (NEXT_INSN (p), QImode); 6937 } 6938 /* Detect a branch around a block of code. */ 6939 else if (skip_blocks && q != 0 && GET_CODE (q) != CODE_LABEL) 6940 { 6941 rtx tmp; 6942 6943 if (next_real_insn (q) == next) 6944 { 6945 p = NEXT_INSN (p); 6946 continue; 6947 } 6948 6949 for (i = 0; i < path_entry; i++) 6950 if (data->path[i].branch == p) 6951 break; 6952 6953 if (i != path_entry) 6954 break; 6955 6956 /* This is no_labels_between_p (p, q) with an added check for 6957 reaching the end of a function (in case Q precedes P). */ 6958 for (tmp = NEXT_INSN (p); tmp && tmp != q; tmp = NEXT_INSN (tmp)) 6959 if (GET_CODE (tmp) == CODE_LABEL) 6960 break; 6961 6962 if (tmp == q) 6963 { 6964 data->path[path_entry].branch = p; 6965 data->path[path_entry++].status = AROUND; 6966 6967 path_size = path_entry; 6968 6969 p = JUMP_LABEL (p); 6970 /* Mark block so we won't scan it again later. */ 6971 PUT_MODE (NEXT_INSN (p), QImode); 6972 } 6973 } 6974 } 6975 p = NEXT_INSN (p); 6976 } 6977 6978 data->low_cuid = low_cuid; 6979 data->high_cuid = high_cuid; 6980 data->nsets = nsets; 6981 data->last = p; 6982 6983 /* If all jumps in the path are not taken, set our path length to zero 6984 so a rescan won't be done. */ 6985 for (i = path_size - 1; i >= 0; i--) 6986 if (data->path[i].status != NOT_TAKEN) 6987 break; 6988 6989 if (i == -1) 6990 data->path_size = 0; 6991 else 6992 data->path_size = path_size; 6993 6994 /* End the current branch path. */ 6995 data->path[path_size].branch = 0; 6996} 6997 6998/* Perform cse on the instructions of a function. 6999 F is the first instruction. 7000 NREGS is one plus the highest pseudo-reg number used in the instruction. 7001 7002 AFTER_LOOP is 1 if this is the cse call done after loop optimization 7003 (only if -frerun-cse-after-loop). 7004 7005 Returns 1 if jump_optimize should be redone due to simplifications 7006 in conditional jump instructions. */ 7007 7008int 7009cse_main (f, nregs, after_loop, file) 7010 rtx f; 7011 int nregs; 7012 int after_loop; 7013 FILE *file; 7014{ 7015 struct cse_basic_block_data val; 7016 rtx insn = f; 7017 int i; 7018 7019 cse_jumps_altered = 0; 7020 recorded_label_ref = 0; 7021 constant_pool_entries_cost = 0; 7022 val.path_size = 0; 7023 7024 init_recog (); 7025 init_alias_analysis (); 7026 7027 max_reg = nregs; 7028 7029 max_insn_uid = get_max_uid (); 7030 7031 reg_eqv_table = (struct reg_eqv_elem *) 7032 xmalloc (nregs * sizeof (struct reg_eqv_elem)); 7033 7034#ifdef LOAD_EXTEND_OP 7035 7036 /* Allocate scratch rtl here. cse_insn will fill in the memory reference 7037 and change the code and mode as appropriate. */ 7038 memory_extend_rtx = gen_rtx_ZERO_EXTEND (VOIDmode, NULL_RTX); 7039#endif 7040 7041 /* Reset the counter indicating how many elements have been made 7042 thus far. */ 7043 n_elements_made = 0; 7044 7045 /* Find the largest uid. */ 7046 7047 max_uid = get_max_uid (); 7048 uid_cuid = (int *) xcalloc (max_uid + 1, sizeof (int)); 7049 7050 /* Compute the mapping from uids to cuids. 7051 CUIDs are numbers assigned to insns, like uids, 7052 except that cuids increase monotonically through the code. 7053 Don't assign cuids to line-number NOTEs, so that the distance in cuids 7054 between two insns is not affected by -g. */ 7055 7056 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) 7057 { 7058 if (GET_CODE (insn) != NOTE 7059 || NOTE_LINE_NUMBER (insn) < 0) 7060 INSN_CUID (insn) = ++i; 7061 else 7062 /* Give a line number note the same cuid as preceding insn. */ 7063 INSN_CUID (insn) = i; 7064 } 7065 7066 ggc_push_context (); 7067 7068 /* Loop over basic blocks. 7069 Compute the maximum number of qty's needed for each basic block 7070 (which is 2 for each SET). */ 7071 insn = f; 7072 while (insn) 7073 { 7074 cse_altered = 0; 7075 cse_end_of_basic_block (insn, &val, flag_cse_follow_jumps, after_loop, 7076 flag_cse_skip_blocks); 7077 7078 /* If this basic block was already processed or has no sets, skip it. */ 7079 if (val.nsets == 0 || GET_MODE (insn) == QImode) 7080 { 7081 PUT_MODE (insn, VOIDmode); 7082 insn = (val.last ? NEXT_INSN (val.last) : 0); 7083 val.path_size = 0; 7084 continue; 7085 } 7086 7087 cse_basic_block_start = val.low_cuid; 7088 cse_basic_block_end = val.high_cuid; 7089 max_qty = val.nsets * 2; 7090 7091 if (file) 7092 fnotice (file, ";; Processing block from %d to %d, %d sets.\n", 7093 INSN_UID (insn), val.last ? INSN_UID (val.last) : 0, 7094 val.nsets); 7095 7096 /* Make MAX_QTY bigger to give us room to optimize 7097 past the end of this basic block, if that should prove useful. */ 7098 if (max_qty < 500) 7099 max_qty = 500; 7100 7101 max_qty += max_reg; 7102 7103 /* If this basic block is being extended by following certain jumps, 7104 (see `cse_end_of_basic_block'), we reprocess the code from the start. 7105 Otherwise, we start after this basic block. */ 7106 if (val.path_size > 0) 7107 cse_basic_block (insn, val.last, val.path, 0); 7108 else 7109 { 7110 int old_cse_jumps_altered = cse_jumps_altered; 7111 rtx temp; 7112 7113 /* When cse changes a conditional jump to an unconditional 7114 jump, we want to reprocess the block, since it will give 7115 us a new branch path to investigate. */ 7116 cse_jumps_altered = 0; 7117 temp = cse_basic_block (insn, val.last, val.path, ! after_loop); 7118 if (cse_jumps_altered == 0 7119 || (flag_cse_follow_jumps == 0 && flag_cse_skip_blocks == 0)) 7120 insn = temp; 7121 7122 cse_jumps_altered |= old_cse_jumps_altered; 7123 } 7124 7125 if (cse_altered) 7126 ggc_collect (); 7127 7128#ifdef USE_C_ALLOCA 7129 alloca (0); 7130#endif 7131 } 7132 7133 ggc_pop_context (); 7134 7135 if (max_elements_made < n_elements_made) 7136 max_elements_made = n_elements_made; 7137 7138 /* Clean up. */ 7139 end_alias_analysis (); 7140 free (uid_cuid); 7141 free (reg_eqv_table); 7142 7143 return cse_jumps_altered || recorded_label_ref; 7144} 7145 7146/* Process a single basic block. FROM and TO and the limits of the basic 7147 block. NEXT_BRANCH points to the branch path when following jumps or 7148 a null path when not following jumps. 7149 7150 AROUND_LOOP is non-zero if we are to try to cse around to the start of a 7151 loop. This is true when we are being called for the last time on a 7152 block and this CSE pass is before loop.c. */ 7153 7154static rtx 7155cse_basic_block (from, to, next_branch, around_loop) 7156 rtx from, to; 7157 struct branch_path *next_branch; 7158 int around_loop; 7159{ 7160 rtx insn; 7161 int to_usage = 0; 7162 rtx libcall_insn = NULL_RTX; 7163 int num_insns = 0; 7164 7165 /* This array is undefined before max_reg, so only allocate 7166 the space actually needed and adjust the start. */ 7167 7168 qty_table 7169 = (struct qty_table_elem *) xmalloc ((max_qty - max_reg) 7170 * sizeof (struct qty_table_elem)); 7171 qty_table -= max_reg; 7172 7173 new_basic_block (); 7174 7175 /* TO might be a label. If so, protect it from being deleted. */ 7176 if (to != 0 && GET_CODE (to) == CODE_LABEL) 7177 ++LABEL_NUSES (to); 7178 7179 for (insn = from; insn != to; insn = NEXT_INSN (insn)) 7180 { 7181 enum rtx_code code = GET_CODE (insn); 7182 7183 /* If we have processed 1,000 insns, flush the hash table to 7184 avoid extreme quadratic behavior. We must not include NOTEs 7185 in the count since there may be more of them when generating 7186 debugging information. If we clear the table at different 7187 times, code generated with -g -O might be different than code 7188 generated with -O but not -g. 7189 7190 ??? This is a real kludge and needs to be done some other way. 7191 Perhaps for 2.9. */ 7192 if (code != NOTE && num_insns++ > 1000) 7193 { 7194 flush_hash_table (); 7195 num_insns = 0; 7196 } 7197 7198 /* See if this is a branch that is part of the path. If so, and it is 7199 to be taken, do so. */ 7200 if (next_branch->branch == insn) 7201 { 7202 enum taken status = next_branch++->status; 7203 if (status != NOT_TAKEN) 7204 { 7205 if (status == TAKEN) 7206 record_jump_equiv (insn, 1); 7207 else 7208 invalidate_skipped_block (NEXT_INSN (insn)); 7209 7210 /* Set the last insn as the jump insn; it doesn't affect cc0. 7211 Then follow this branch. */ 7212#ifdef HAVE_cc0 7213 prev_insn_cc0 = 0; 7214#endif 7215 prev_insn = insn; 7216 insn = JUMP_LABEL (insn); 7217 continue; 7218 } 7219 } 7220 7221 if (GET_MODE (insn) == QImode) 7222 PUT_MODE (insn, VOIDmode); 7223 7224 if (GET_RTX_CLASS (code) == 'i') 7225 { 7226 rtx p; 7227 7228 /* Process notes first so we have all notes in canonical forms when 7229 looking for duplicate operations. */ 7230 7231 if (REG_NOTES (insn)) 7232 REG_NOTES (insn) = cse_process_notes (REG_NOTES (insn), NULL_RTX); 7233 7234 /* Track when we are inside in LIBCALL block. Inside such a block, 7235 we do not want to record destinations. The last insn of a 7236 LIBCALL block is not considered to be part of the block, since 7237 its destination is the result of the block and hence should be 7238 recorded. */ 7239 7240 if (REG_NOTES (insn) != 0) 7241 { 7242 if ((p = find_reg_note (insn, REG_LIBCALL, NULL_RTX))) 7243 libcall_insn = XEXP (p, 0); 7244 else if (find_reg_note (insn, REG_RETVAL, NULL_RTX)) 7245 libcall_insn = 0; 7246 } 7247 7248 cse_insn (insn, libcall_insn); 7249 7250 /* If we haven't already found an insn where we added a LABEL_REF, 7251 check this one. */ 7252 if (GET_CODE (insn) == INSN && ! recorded_label_ref 7253 && for_each_rtx (&PATTERN (insn), check_for_label_ref, 7254 (void *) insn)) 7255 recorded_label_ref = 1; 7256 } 7257 7258 /* If INSN is now an unconditional jump, skip to the end of our 7259 basic block by pretending that we just did the last insn in the 7260 basic block. If we are jumping to the end of our block, show 7261 that we can have one usage of TO. */ 7262 7263 if (any_uncondjump_p (insn)) 7264 { 7265 if (to == 0) 7266 { 7267 free (qty_table + max_reg); 7268 return 0; 7269 } 7270 7271 if (JUMP_LABEL (insn) == to) 7272 to_usage = 1; 7273 7274 /* Maybe TO was deleted because the jump is unconditional. 7275 If so, there is nothing left in this basic block. */ 7276 /* ??? Perhaps it would be smarter to set TO 7277 to whatever follows this insn, 7278 and pretend the basic block had always ended here. */ 7279 if (INSN_DELETED_P (to)) 7280 break; 7281 7282 insn = PREV_INSN (to); 7283 } 7284 7285 /* See if it is ok to keep on going past the label 7286 which used to end our basic block. Remember that we incremented 7287 the count of that label, so we decrement it here. If we made 7288 a jump unconditional, TO_USAGE will be one; in that case, we don't 7289 want to count the use in that jump. */ 7290 7291 if (to != 0 && NEXT_INSN (insn) == to 7292 && GET_CODE (to) == CODE_LABEL && --LABEL_NUSES (to) == to_usage) 7293 { 7294 struct cse_basic_block_data val; 7295 rtx prev; 7296 7297 insn = NEXT_INSN (to); 7298 7299 /* If TO was the last insn in the function, we are done. */ 7300 if (insn == 0) 7301 { 7302 free (qty_table + max_reg); 7303 return 0; 7304 } 7305 7306 /* If TO was preceded by a BARRIER we are done with this block 7307 because it has no continuation. */ 7308 prev = prev_nonnote_insn (to); 7309 if (prev && GET_CODE (prev) == BARRIER) 7310 { 7311 free (qty_table + max_reg); 7312 return insn; 7313 } 7314 7315 /* Find the end of the following block. Note that we won't be 7316 following branches in this case. */ 7317 to_usage = 0; 7318 val.path_size = 0; 7319 cse_end_of_basic_block (insn, &val, 0, 0, 0); 7320 7321 /* If the tables we allocated have enough space left 7322 to handle all the SETs in the next basic block, 7323 continue through it. Otherwise, return, 7324 and that block will be scanned individually. */ 7325 if (val.nsets * 2 + next_qty > max_qty) 7326 break; 7327 7328 cse_basic_block_start = val.low_cuid; 7329 cse_basic_block_end = val.high_cuid; 7330 to = val.last; 7331 7332 /* Prevent TO from being deleted if it is a label. */ 7333 if (to != 0 && GET_CODE (to) == CODE_LABEL) 7334 ++LABEL_NUSES (to); 7335 7336 /* Back up so we process the first insn in the extension. */ 7337 insn = PREV_INSN (insn); 7338 } 7339 } 7340 7341 if (next_qty > max_qty) 7342 abort (); 7343 7344 /* If we are running before loop.c, we stopped on a NOTE_INSN_LOOP_END, and 7345 the previous insn is the only insn that branches to the head of a loop, 7346 we can cse into the loop. Don't do this if we changed the jump 7347 structure of a loop unless we aren't going to be following jumps. */ 7348 7349 insn = prev_nonnote_insn(to); 7350 if ((cse_jumps_altered == 0 7351 || (flag_cse_follow_jumps == 0 && flag_cse_skip_blocks == 0)) 7352 && around_loop && to != 0 7353 && GET_CODE (to) == NOTE && NOTE_LINE_NUMBER (to) == NOTE_INSN_LOOP_END 7354 && GET_CODE (insn) == JUMP_INSN 7355 && JUMP_LABEL (insn) != 0 7356 && LABEL_NUSES (JUMP_LABEL (insn)) == 1) 7357 cse_around_loop (JUMP_LABEL (insn)); 7358 7359 free (qty_table + max_reg); 7360 7361 return to ? NEXT_INSN (to) : 0; 7362} 7363 7364/* Called via for_each_rtx to see if an insn is using a LABEL_REF for which 7365 there isn't a REG_LABEL note. Return one if so. DATA is the insn. */ 7366 7367static int 7368check_for_label_ref (rtl, data) 7369 rtx *rtl; 7370 void *data; 7371{ 7372 rtx insn = (rtx) data; 7373 7374 /* If this insn uses a LABEL_REF and there isn't a REG_LABEL note for it, 7375 we must rerun jump since it needs to place the note. If this is a 7376 LABEL_REF for a CODE_LABEL that isn't in the insn chain, don't do this 7377 since no REG_LABEL will be added. */ 7378 return (GET_CODE (*rtl) == LABEL_REF 7379 && ! LABEL_REF_NONLOCAL_P (*rtl) 7380 && LABEL_P (XEXP (*rtl, 0)) 7381 && INSN_UID (XEXP (*rtl, 0)) != 0 7382 && ! find_reg_note (insn, REG_LABEL, XEXP (*rtl, 0))); 7383} 7384 7385/* Count the number of times registers are used (not set) in X. 7386 COUNTS is an array in which we accumulate the count, INCR is how much 7387 we count each register usage. 7388 7389 Don't count a usage of DEST, which is the SET_DEST of a SET which 7390 contains X in its SET_SRC. This is because such a SET does not 7391 modify the liveness of DEST. */ 7392 7393static void 7394count_reg_usage (x, counts, dest, incr) 7395 rtx x; 7396 int *counts; 7397 rtx dest; 7398 int incr; 7399{ 7400 enum rtx_code code; 7401 const char *fmt; 7402 int i, j; 7403 7404 if (x == 0) 7405 return; 7406 7407 switch (code = GET_CODE (x)) 7408 { 7409 case REG: 7410 if (x != dest) 7411 counts[REGNO (x)] += incr; 7412 return; 7413 7414 case PC: 7415 case CC0: 7416 case CONST: 7417 case CONST_INT: 7418 case CONST_DOUBLE: 7419 case SYMBOL_REF: 7420 case LABEL_REF: 7421 return; 7422 7423 case CLOBBER: 7424 /* If we are clobbering a MEM, mark any registers inside the address 7425 as being used. */ 7426 if (GET_CODE (XEXP (x, 0)) == MEM) 7427 count_reg_usage (XEXP (XEXP (x, 0), 0), counts, NULL_RTX, incr); 7428 return; 7429 7430 case SET: 7431 /* Unless we are setting a REG, count everything in SET_DEST. */ 7432 if (GET_CODE (SET_DEST (x)) != REG) 7433 count_reg_usage (SET_DEST (x), counts, NULL_RTX, incr); 7434 7435 /* If SRC has side-effects, then we can't delete this insn, so the 7436 usage of SET_DEST inside SRC counts. 7437 7438 ??? Strictly-speaking, we might be preserving this insn 7439 because some other SET has side-effects, but that's hard 7440 to do and can't happen now. */ 7441 count_reg_usage (SET_SRC (x), counts, 7442 side_effects_p (SET_SRC (x)) ? NULL_RTX : SET_DEST (x), 7443 incr); 7444 return; 7445 7446 case CALL_INSN: 7447 count_reg_usage (CALL_INSN_FUNCTION_USAGE (x), counts, NULL_RTX, incr); 7448 /* Fall through. */ 7449 7450 case INSN: 7451 case JUMP_INSN: 7452 count_reg_usage (PATTERN (x), counts, NULL_RTX, incr); 7453 7454 /* Things used in a REG_EQUAL note aren't dead since loop may try to 7455 use them. */ 7456 7457 count_reg_usage (REG_NOTES (x), counts, NULL_RTX, incr); 7458 return; 7459 7460 case EXPR_LIST: 7461 case INSN_LIST: 7462 if (REG_NOTE_KIND (x) == REG_EQUAL 7463 || (REG_NOTE_KIND (x) != REG_NONNEG && GET_CODE (XEXP (x,0)) == USE)) 7464 count_reg_usage (XEXP (x, 0), counts, NULL_RTX, incr); 7465 count_reg_usage (XEXP (x, 1), counts, NULL_RTX, incr); 7466 return; 7467 7468 default: 7469 break; 7470 } 7471 7472 fmt = GET_RTX_FORMAT (code); 7473 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 7474 { 7475 if (fmt[i] == 'e') 7476 count_reg_usage (XEXP (x, i), counts, dest, incr); 7477 else if (fmt[i] == 'E') 7478 for (j = XVECLEN (x, i) - 1; j >= 0; j--) 7479 count_reg_usage (XVECEXP (x, i, j), counts, dest, incr); 7480 } 7481} 7482 7483/* Return true if set is live. */ 7484static bool 7485set_live_p (set, insn, counts) 7486 rtx set; 7487 rtx insn ATTRIBUTE_UNUSED; /* Only used with HAVE_cc0. */ 7488 int *counts; 7489{ 7490#ifdef HAVE_cc0 7491 rtx tem; 7492#endif 7493 7494 if (set_noop_p (set)) 7495 ; 7496 7497#ifdef HAVE_cc0 7498 else if (GET_CODE (SET_DEST (set)) == CC0 7499 && !side_effects_p (SET_SRC (set)) 7500 && ((tem = next_nonnote_insn (insn)) == 0 7501 || !INSN_P (tem) 7502 || !reg_referenced_p (cc0_rtx, PATTERN (tem)))) 7503 return false; 7504#endif 7505 else if (GET_CODE (SET_DEST (set)) != REG 7506 || REGNO (SET_DEST (set)) < FIRST_PSEUDO_REGISTER 7507 || counts[REGNO (SET_DEST (set))] != 0 7508 || side_effects_p (SET_SRC (set)) 7509 /* An ADDRESSOF expression can turn into a use of the 7510 internal arg pointer, so always consider the 7511 internal arg pointer live. If it is truly dead, 7512 flow will delete the initializing insn. */ 7513 || (SET_DEST (set) == current_function_internal_arg_pointer)) 7514 return true; 7515 return false; 7516} 7517 7518/* Return true if insn is live. */ 7519 7520static bool 7521insn_live_p (insn, counts) 7522 rtx insn; 7523 int *counts; 7524{ 7525 int i; 7526 if (GET_CODE (PATTERN (insn)) == SET) 7527 return set_live_p (PATTERN (insn), insn, counts); 7528 else if (GET_CODE (PATTERN (insn)) == PARALLEL) 7529 { 7530 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--) 7531 { 7532 rtx elt = XVECEXP (PATTERN (insn), 0, i); 7533 7534 if (GET_CODE (elt) == SET) 7535 { 7536 if (set_live_p (elt, insn, counts)) 7537 return true; 7538 } 7539 else if (GET_CODE (elt) != CLOBBER && GET_CODE (elt) != USE) 7540 return true; 7541 } 7542 return false; 7543 } 7544 else 7545 return true; 7546} 7547 7548/* Return true if libcall is dead as a whole. */ 7549 7550static bool 7551dead_libcall_p (insn) 7552 rtx insn; 7553{ 7554 rtx note; 7555 /* See if there's a REG_EQUAL note on this insn and try to 7556 replace the source with the REG_EQUAL expression. 7557 7558 We assume that insns with REG_RETVALs can only be reg->reg 7559 copies at this point. */ 7560 note = find_reg_note (insn, REG_EQUAL, NULL_RTX); 7561 if (note) 7562 { 7563 rtx set = single_set (insn); 7564 rtx new = simplify_rtx (XEXP (note, 0)); 7565 7566 if (!new) 7567 new = XEXP (note, 0); 7568 7569 if (set && validate_change (insn, &SET_SRC (set), new, 0)) 7570 { 7571 remove_note (insn, find_reg_note (insn, REG_RETVAL, NULL_RTX)); 7572 return true; 7573 } 7574 } 7575 return false; 7576} 7577 7578/* Scan all the insns and delete any that are dead; i.e., they store a register 7579 that is never used or they copy a register to itself. 7580 7581 This is used to remove insns made obviously dead by cse, loop or other 7582 optimizations. It improves the heuristics in loop since it won't try to 7583 move dead invariants out of loops or make givs for dead quantities. The 7584 remaining passes of the compilation are also sped up. */ 7585 7586void 7587delete_trivially_dead_insns (insns, nreg, preserve_basic_blocks) 7588 rtx insns; 7589 int nreg; 7590 int preserve_basic_blocks; 7591{ 7592 int *counts; 7593 rtx insn, prev; 7594 int i; 7595 int in_libcall = 0, dead_libcall = 0; 7596 basic_block bb; 7597 7598 /* First count the number of times each register is used. */ 7599 counts = (int *) xcalloc (nreg, sizeof (int)); 7600 for (insn = next_real_insn (insns); insn; insn = next_real_insn (insn)) 7601 count_reg_usage (insn, counts, NULL_RTX, 1); 7602 7603 /* Go from the last insn to the first and delete insns that only set unused 7604 registers or copy a register to itself. As we delete an insn, remove 7605 usage counts for registers it uses. 7606 7607 The first jump optimization pass may leave a real insn as the last 7608 insn in the function. We must not skip that insn or we may end 7609 up deleting code that is not really dead. */ 7610 insn = get_last_insn (); 7611 if (! INSN_P (insn)) 7612 insn = prev_real_insn (insn); 7613 7614 if (!preserve_basic_blocks) 7615 for (; insn; insn = prev) 7616 { 7617 int live_insn = 0; 7618 7619 prev = prev_real_insn (insn); 7620 7621 /* Don't delete any insns that are part of a libcall block unless 7622 we can delete the whole libcall block. 7623 7624 Flow or loop might get confused if we did that. Remember 7625 that we are scanning backwards. */ 7626 if (find_reg_note (insn, REG_RETVAL, NULL_RTX)) 7627 { 7628 in_libcall = 1; 7629 live_insn = 1; 7630 dead_libcall = dead_libcall_p (insn); 7631 } 7632 else if (in_libcall) 7633 live_insn = ! dead_libcall; 7634 else 7635 live_insn = insn_live_p (insn, counts); 7636 7637 /* If this is a dead insn, delete it and show registers in it aren't 7638 being used. */ 7639 7640 if (! live_insn) 7641 { 7642 count_reg_usage (insn, counts, NULL_RTX, -1); 7643 delete_related_insns (insn); 7644 } 7645 7646 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX)) 7647 { 7648 in_libcall = 0; 7649 dead_libcall = 0; 7650 } 7651 } 7652 else 7653 for (i = 0; i < n_basic_blocks; i++) 7654 for (bb = BASIC_BLOCK (i), insn = bb->end; insn != bb->head; insn = prev) 7655 { 7656 int live_insn = 0; 7657 7658 prev = PREV_INSN (insn); 7659 if (!INSN_P (insn)) 7660 continue; 7661 7662 /* Don't delete any insns that are part of a libcall block unless 7663 we can delete the whole libcall block. 7664 7665 Flow or loop might get confused if we did that. Remember 7666 that we are scanning backwards. */ 7667 if (find_reg_note (insn, REG_RETVAL, NULL_RTX)) 7668 { 7669 in_libcall = 1; 7670 live_insn = 1; 7671 dead_libcall = dead_libcall_p (insn); 7672 } 7673 else if (in_libcall) 7674 live_insn = ! dead_libcall; 7675 else 7676 live_insn = insn_live_p (insn, counts); 7677 7678 /* If this is a dead insn, delete it and show registers in it aren't 7679 being used. */ 7680 7681 if (! live_insn) 7682 { 7683 count_reg_usage (insn, counts, NULL_RTX, -1); 7684 delete_insn (insn); 7685 } 7686 7687 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX)) 7688 { 7689 in_libcall = 0; 7690 dead_libcall = 0; 7691 } 7692 } 7693 7694 /* Clean up. */ 7695 free (counts); 7696} 7697