reload.h revision 52284 
1/* Communication between reload.c and reload1.c.
2   Copyright (C) 1987, 91-95, 97, 1998 Free Software Foundation, Inc.
3
4This file is part of GNU CC.
5
6GNU CC is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 2, or (at your option)
9any later version.
10
11GNU CC is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14GNU General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along with GNU CC; see the file COPYING.  If not, write to
18the Free Software Foundation, 59 Temple Place - Suite 330,
19Boston, MA 02111-1307, USA.  */
20
21
22/* If secondary reloads are the same for inputs and outputs, define those
23   macros here.  */
24
25#ifdef SECONDARY_RELOAD_CLASS
26#define SECONDARY_INPUT_RELOAD_CLASS(CLASS, MODE, X) \
27  SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
28#define SECONDARY_OUTPUT_RELOAD_CLASS(CLASS, MODE, X) \
29  SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
30#endif
31
32/* If either macro is defined, show that we need secondary reloads.  */
33#if defined(SECONDARY_INPUT_RELOAD_CLASS) || defined(SECONDARY_OUTPUT_RELOAD_CLASS)
34#define HAVE_SECONDARY_RELOADS
35#endif
36
37/* If MEMORY_MOVE_COST isn't defined, give it a default here.  */
38#ifndef MEMORY_MOVE_COST
39#ifdef HAVE_SECONDARY_RELOADS
40#define MEMORY_MOVE_COST(MODE,CLASS,IN) \
41  (4 + memory_move_secondary_cost ((MODE), (CLASS), (IN)))
42#else
43#define MEMORY_MOVE_COST(MODE,CLASS,IN) 4
44#endif
45#endif
46extern int memory_move_secondary_cost PROTO ((enum machine_mode, enum reg_class, int));
47
48/* See reload.c and reload1.c for comments on these variables.  */
49
50/* Maximum number of reloads we can need.  */
51#define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
52
53extern rtx reload_in[MAX_RELOADS];
54extern rtx reload_out[MAX_RELOADS];
55extern rtx reload_in_reg[MAX_RELOADS];
56extern rtx reload_out_reg[MAX_RELOADS];
57extern enum reg_class reload_reg_class[MAX_RELOADS];
58extern enum machine_mode reload_inmode[MAX_RELOADS];
59extern enum machine_mode reload_outmode[MAX_RELOADS];
60extern char reload_optional[MAX_RELOADS];
61extern char reload_nongroup[MAX_RELOADS];
62extern int reload_inc[MAX_RELOADS];
63extern int reload_opnum[MAX_RELOADS];
64extern int reload_secondary_p[MAX_RELOADS];
65extern int reload_secondary_in_reload[MAX_RELOADS];
66extern int reload_secondary_out_reload[MAX_RELOADS];
67#ifdef MAX_INSN_CODE
68extern enum insn_code reload_secondary_in_icode[MAX_RELOADS];
69extern enum insn_code reload_secondary_out_icode[MAX_RELOADS];
70#endif
71extern int n_reloads;
72
73extern rtx reload_reg_rtx[MAX_RELOADS];
74
75/* Encode the usage of a reload.  The following codes are supported:
76
77   RELOAD_FOR_INPUT		reload of an input operand
78   RELOAD_FOR_OUTPUT		likewise, for output
79   RELOAD_FOR_INSN		a reload that must not conflict with anything
80				used in the insn, but may conflict with
81				something used before or after the insn
82   RELOAD_FOR_INPUT_ADDRESS	reload for parts of the address of an object
83				that is an input reload
84   RELOAD_FOR_INPADDR_ADDRESS	reload needed for RELOAD_FOR_INPUT_ADDRESS
85   RELOAD_FOR_OUTPUT_ADDRESS	like RELOAD_FOR INPUT_ADDRESS, for output
86   RELOAD_FOR_OUTADDR_ADDRESS	reload needed for RELOAD_FOR_OUTPUT_ADDRESS
87   RELOAD_FOR_OPERAND_ADDRESS	reload for the address of a non-reloaded
88				operand; these don't conflict with
89				any other addresses.
90   RELOAD_FOR_OPADDR_ADDR	reload needed for RELOAD_FOR_OPERAND_ADDRESS
91                                reloads; usually secondary reloads
92   RELOAD_OTHER			none of the above, usually multiple uses
93   RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
94   				that is marked RELOAD_OTHER.
95
96   This used to be "enum reload_when_needed" but some debuggers have trouble
97   with an enum tag and variable of the same name.  */
98
99enum reload_type
100{
101  RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
102  RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
103  RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
104  RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
105  RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
106};
107
108extern enum reload_type reload_when_needed[MAX_RELOADS];
109
110extern rtx *reg_equiv_constant;
111extern rtx *reg_equiv_memory_loc;
112extern rtx *reg_equiv_address;
113extern rtx *reg_equiv_mem;
114
115/* All the "earlyclobber" operands of the current insn
116   are recorded here.  */
117extern int n_earlyclobbers;
118extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
119
120/* Save the number of operands.  */
121extern int reload_n_operands;
122
123/* First uid used by insns created by reload in this function.
124   Used in find_equiv_reg.  */
125extern int reload_first_uid;
126
127/* Nonzero if indirect addressing is supported when the innermost MEM is
128   of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
129   which these are valid is the same as spill_indirect_levels, above.   */
130
131extern char indirect_symref_ok;
132
133/* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
134extern char double_reg_address_ok;
135
136extern int num_not_at_initial_offset;
137
138#ifdef MAX_INSN_CODE
139/* These arrays record the insn_code of insns that may be needed to
140   perform input and output reloads of special objects.  They provide a
141   place to pass a scratch register.  */
142extern enum insn_code reload_in_optab[];
143extern enum insn_code reload_out_optab[];
144#endif
145
146struct needs
147{
148  /* [0] is normal, [1] is nongroup.  */
149  short regs[2][N_REG_CLASSES];
150  short groups[N_REG_CLASSES];
151};
152
153#if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
154/* This structure describes instructions which are relevant for reload.
155   Apart from all regular insns, this also includes CODE_LABELs, since they
156   must be examined for register elimination.  */
157struct insn_chain
158{
159  /* Links to the neighbour instructions.  */
160  struct insn_chain *next, *prev;
161
162  /* Link through a chains set up by calculate_needs_all_insns, containing
163     all insns that need reloading.  */
164  struct insn_chain *next_need_reload;
165
166  /* The basic block this insn is in.  */
167  int block;
168  /* The rtx of the insn.  */
169  rtx insn;
170  /* Register life information: record all live hard registers, and all
171     live pseudos that have a hard register.
172     This information is recorded for the point immediately before the insn
173     (in live_before), and for the point within the insn at which all
174     outputs have just been written to (in live_after).  */
175  regset live_before;
176  regset live_after;
177
178  /* For each class, size of group of consecutive regs
179     that is needed for the reloads of this class.  */
180  char group_size[N_REG_CLASSES];
181  /* For each class, the machine mode which requires consecutive
182     groups of regs of that class.
183     If two different modes ever require groups of one class,
184     they must be the same size and equally restrictive for that class,
185     otherwise we can't handle the complexity.  */
186  enum machine_mode group_mode[N_REG_CLASSES];
187
188  /* Indicates if a register was counted against the need for
189     groups.  0 means it can count against max_nongroup instead.  */
190  HARD_REG_SET counted_for_groups;
191
192  /* Indicates if a register was counted against the need for
193     non-groups.  0 means it can become part of a new group.
194     During choose_reload_regs, 1 here means don't use this reg
195     as part of a group, even if it seems to be otherwise ok.  */
196  HARD_REG_SET counted_for_nongroups;
197
198  /* Indicates which registers have already been used for spills.  */
199  HARD_REG_SET used_spill_regs;
200
201  /* Describe the needs for reload registers of this insn.  */
202  struct needs need;
203
204  /* Nonzero if find_reloads said the insn requires reloading.  */
205  unsigned int need_reload:1;
206  /* Nonzero if find_reloads needs to be run during reload_as_needed to
207     perform modifications on any operands.  */
208  unsigned int need_operand_change:1;
209  /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
210  unsigned int need_elim:1;
211  /* Nonzero if this insn was inserted by perform_caller_saves.  */
212  unsigned int is_caller_save_insn:1;
213};
214
215/* A chain of insn_chain structures to describe all non-note insns in
216   a function.  */
217extern struct insn_chain *reload_insn_chain;
218
219/* Allocate a new insn_chain structure.  */
220extern struct insn_chain *new_insn_chain	PROTO((void));
221
222extern void compute_use_by_pseudos		PROTO((HARD_REG_SET *, regset));
223#endif
224
225/* Functions from reload.c:  */
226
227/* Return a memory location that will be used to copy X in mode MODE.
228   If we haven't already made a location for this mode in this insn,
229   call find_reloads_address on the location being returned.  */
230extern rtx get_secondary_mem PROTO((rtx, enum machine_mode,
231				    int, enum reload_type));
232
233/* Clear any secondary memory locations we've made.  */
234extern void clear_secondary_mem PROTO((void));
235
236/* Transfer all replacements that used to be in reload FROM to be in
237   reload TO.  */
238extern void transfer_replacements PROTO((int, int));
239
240/* IN_RTX is the value loaded by a reload that we now decided to inherit,
241   or a subpart of it.  If we have any replacements registered for IN_RTX,
242   chancel the reloads that were supposed to load them.
243   Return non-zero if we chanceled any reloads.  */
244extern int remove_address_replacements PROTO((rtx in_rtx));
245
246/* Like rtx_equal_p except that it allows a REG and a SUBREG to match
247   if they are the same hard reg, and has special hacks for
248   autoincrement and autodecrement.  */
249extern int operands_match_p PROTO((rtx, rtx));
250
251/* Return 1 if altering OP will not modify the value of CLOBBER. */
252extern int safe_from_earlyclobber PROTO((rtx, rtx));
253
254/* Search the body of INSN for values that need reloading and record them
255   with push_reload.  REPLACE nonzero means record also where the values occur
256   so that subst_reloads can be used.  */
257extern int find_reloads PROTO((rtx, int, int, int, short *));
258
259/* Compute the sum of X and Y, making canonicalizations assumed in an
260   address, namely: sum constant integers, surround the sum of two
261   constants with a CONST, put the constant as the second operand, and
262   group the constant on the outermost sum.  */
263extern rtx form_sum PROTO((rtx, rtx));
264
265/* Substitute into the current INSN the registers into which we have reloaded
266   the things that need reloading.  */
267extern void subst_reloads PROTO((void));
268
269/* Make a copy of any replacements being done into X and move those copies
270   to locations in Y, a copy of X.  We only look at the highest level of
271   the RTL.  */
272extern void copy_replacements PROTO((rtx, rtx));
273
274/* Change any replacements being done to *X to be done to *Y */
275extern void move_replacements PROTO((rtx *x, rtx *y));
276
277/* If LOC was scheduled to be replaced by something, return the replacement.
278   Otherwise, return *LOC.  */
279extern rtx find_replacement PROTO((rtx *));
280
281/* Return nonzero if register in range [REGNO, ENDREGNO)
282   appears either explicitly or implicitly in X
283   other than being stored into.  */
284extern int refers_to_regno_for_reload_p PROTO((int, int, rtx, rtx *));
285
286/* Nonzero if modifying X will affect IN.  */
287extern int reg_overlap_mentioned_for_reload_p PROTO((rtx, rtx));
288
289/* Return nonzero if anything in X contains a MEM.  Look also for pseudo
290   registers.  */
291extern int refers_to_mem_for_reload_p PROTO((rtx));
292
293/* Check the insns before INSN to see if there is a suitable register
294   containing the same value as GOAL.  */
295extern rtx find_equiv_reg PROTO((rtx, rtx, enum reg_class, int, short *,
296				 int, enum machine_mode));
297
298/* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
299extern int regno_clobbered_p PROTO((int, rtx));
300
301/* Functions in reload1.c:  */
302
303extern int reloads_conflict		PROTO ((int, int));
304
305int count_occurrences            PROTO((rtx, rtx));
306
307/* Initialize the reload pass once per compilation.  */
308extern void init_reload PROTO((void));
309
310/* The reload pass itself.  */
311extern int reload PROTO((rtx, int, FILE *));
312
313/* Mark the slots in regs_ever_live for the hard regs
314   used by pseudo-reg number REGNO.  */
315extern void mark_home_live PROTO((int));
316
317/* Scan X and replace any eliminable registers (such as fp) with a
318   replacement (such as sp), plus an offset.  */
319extern rtx eliminate_regs PROTO((rtx, enum machine_mode, rtx));
320
321/* Emit code to perform a reload from IN (which may be a reload register) to
322   OUT (which may also be a reload register).  IN or OUT is from operand
323   OPNUM with reload type TYPE.  */
324extern rtx gen_reload PROTO((rtx, rtx, int, enum reload_type));
325
326/* Deallocate the reload register used by reload number R.  */
327extern void deallocate_reload_reg PROTO((int r));
328
329/* Functions in caller-save.c:  */
330
331/* Initialize for caller-save.  */
332extern void init_caller_save PROTO((void));
333
334/* Initialize save areas by showing that we haven't allocated any yet.  */
335extern void init_save_areas PROTO((void));
336
337/* Allocate save areas for any hard registers that might need saving.  */
338extern void setup_save_areas PROTO((void));
339
340/* Find the places where hard regs are live across calls and save them.  */
341extern void save_call_clobbered_regs PROTO((void));
342
343/* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
344extern void cleanup_subreg_operands PROTO ((rtx));
345