flow.c revision 102780
1/* Data flow analysis for GNU compiler. 2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 3 1999, 2000, 2001 Free Software Foundation, Inc. 4 5This file is part of GCC. 6 7GCC is free software; you can redistribute it and/or modify it under 8the terms of the GNU General Public License as published by the Free 9Software Foundation; either version 2, or (at your option) any later 10version. 11 12GCC is distributed in the hope that it will be useful, but WITHOUT ANY 13WARRANTY; without even the implied warranty of MERCHANTABILITY or 14FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15for more details. 16 17You should have received a copy of the GNU General Public License 18along with GCC; see the file COPYING. If not, write to the Free 19Software Foundation, 59 Temple Place - Suite 330, Boston, MA 2002111-1307, USA. */ 21 22/* This file contains the data flow analysis pass of the compiler. It 23 computes data flow information which tells combine_instructions 24 which insns to consider combining and controls register allocation. 25 26 Additional data flow information that is too bulky to record is 27 generated during the analysis, and is used at that time to create 28 autoincrement and autodecrement addressing. 29 30 The first step is dividing the function into basic blocks. 31 find_basic_blocks does this. Then life_analysis determines 32 where each register is live and where it is dead. 33 34 ** find_basic_blocks ** 35 36 find_basic_blocks divides the current function's rtl into basic 37 blocks and constructs the CFG. The blocks are recorded in the 38 basic_block_info array; the CFG exists in the edge structures 39 referenced by the blocks. 40 41 find_basic_blocks also finds any unreachable loops and deletes them. 42 43 ** life_analysis ** 44 45 life_analysis is called immediately after find_basic_blocks. 46 It uses the basic block information to determine where each 47 hard or pseudo register is live. 48 49 ** live-register info ** 50 51 The information about where each register is live is in two parts: 52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start. 53 54 basic_block->global_live_at_start has an element for each basic 55 block, and the element is a bit-vector with a bit for each hard or 56 pseudo register. The bit is 1 if the register is live at the 57 beginning of the basic block. 58 59 Two types of elements can be added to an insn's REG_NOTES. 60 A REG_DEAD note is added to an insn's REG_NOTES for any register 61 that meets both of two conditions: The value in the register is not 62 needed in subsequent insns and the insn does not replace the value in 63 the register (in the case of multi-word hard registers, the value in 64 each register must be replaced by the insn to avoid a REG_DEAD note). 65 66 In the vast majority of cases, an object in a REG_DEAD note will be 67 used somewhere in the insn. The (rare) exception to this is if an 68 insn uses a multi-word hard register and only some of the registers are 69 needed in subsequent insns. In that case, REG_DEAD notes will be 70 provided for those hard registers that are not subsequently needed. 71 Partial REG_DEAD notes of this type do not occur when an insn sets 72 only some of the hard registers used in such a multi-word operand; 73 omitting REG_DEAD notes for objects stored in an insn is optional and 74 the desire to do so does not justify the complexity of the partial 75 REG_DEAD notes. 76 77 REG_UNUSED notes are added for each register that is set by the insn 78 but is unused subsequently (if every register set by the insn is unused 79 and the insn does not reference memory or have some other side-effect, 80 the insn is deleted instead). If only part of a multi-word hard 81 register is used in a subsequent insn, REG_UNUSED notes are made for 82 the parts that will not be used. 83 84 To determine which registers are live after any insn, one can 85 start from the beginning of the basic block and scan insns, noting 86 which registers are set by each insn and which die there. 87 88 ** Other actions of life_analysis ** 89 90 life_analysis sets up the LOG_LINKS fields of insns because the 91 information needed to do so is readily available. 92 93 life_analysis deletes insns whose only effect is to store a value 94 that is never used. 95 96 life_analysis notices cases where a reference to a register as 97 a memory address can be combined with a preceding or following 98 incrementation or decrementation of the register. The separate 99 instruction to increment or decrement is deleted and the address 100 is changed to a POST_INC or similar rtx. 101 102 Each time an incrementing or decrementing address is created, 103 a REG_INC element is added to the insn's REG_NOTES list. 104 105 life_analysis fills in certain vectors containing information about 106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH, 107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK. 108 109 life_analysis sets current_function_sp_is_unchanging if the function 110 doesn't modify the stack pointer. */ 111 112/* TODO: 113 114 Split out from life_analysis: 115 - local property discovery (bb->local_live, bb->local_set) 116 - global property computation 117 - log links creation 118 - pre/post modify transformation 119*/ 120 121#include "config.h" 122#include "system.h" 123#include "tree.h" 124#include "rtl.h" 125#include "tm_p.h" 126#include "hard-reg-set.h" 127#include "basic-block.h" 128#include "insn-config.h" 129#include "regs.h" 130#include "flags.h" 131#include "output.h" 132#include "function.h" 133#include "except.h" 134#include "toplev.h" 135#include "recog.h" 136#include "expr.h" 137#include "ssa.h" 138#include "timevar.h" 139 140#include "obstack.h" 141#include "splay-tree.h" 142 143#define obstack_chunk_alloc xmalloc 144#define obstack_chunk_free free 145 146/* EXIT_IGNORE_STACK should be nonzero if, when returning from a function, 147 the stack pointer does not matter. The value is tested only in 148 functions that have frame pointers. 149 No definition is equivalent to always zero. */ 150#ifndef EXIT_IGNORE_STACK 151#define EXIT_IGNORE_STACK 0 152#endif 153 154#ifndef HAVE_epilogue 155#define HAVE_epilogue 0 156#endif 157#ifndef HAVE_prologue 158#define HAVE_prologue 0 159#endif 160#ifndef HAVE_sibcall_epilogue 161#define HAVE_sibcall_epilogue 0 162#endif 163 164#ifndef LOCAL_REGNO 165#define LOCAL_REGNO(REGNO) 0 166#endif 167#ifndef EPILOGUE_USES 168#define EPILOGUE_USES(REGNO) 0 169#endif 170#ifndef EH_USES 171#define EH_USES(REGNO) 0 172#endif 173 174#ifdef HAVE_conditional_execution 175#ifndef REVERSE_CONDEXEC_PREDICATES_P 176#define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y)) 177#endif 178#endif 179 180/* Nonzero if the second flow pass has completed. */ 181int flow2_completed; 182 183/* Maximum register number used in this function, plus one. */ 184 185int max_regno; 186 187/* Indexed by n, giving various register information */ 188 189varray_type reg_n_info; 190 191/* Size of a regset for the current function, 192 in (1) bytes and (2) elements. */ 193 194int regset_bytes; 195int regset_size; 196 197/* Regset of regs live when calls to `setjmp'-like functions happen. */ 198/* ??? Does this exist only for the setjmp-clobbered warning message? */ 199 200regset regs_live_at_setjmp; 201 202/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers 203 that have to go in the same hard reg. 204 The first two regs in the list are a pair, and the next two 205 are another pair, etc. */ 206rtx regs_may_share; 207 208/* Callback that determines if it's ok for a function to have no 209 noreturn attribute. */ 210int (*lang_missing_noreturn_ok_p) PARAMS ((tree)); 211 212/* Set of registers that may be eliminable. These are handled specially 213 in updating regs_ever_live. */ 214 215static HARD_REG_SET elim_reg_set; 216 217/* Holds information for tracking conditional register life information. */ 218struct reg_cond_life_info 219{ 220 /* A boolean expression of conditions under which a register is dead. */ 221 rtx condition; 222 /* Conditions under which a register is dead at the basic block end. */ 223 rtx orig_condition; 224 225 /* A boolean expression of conditions under which a register has been 226 stored into. */ 227 rtx stores; 228 229 /* ??? Could store mask of bytes that are dead, so that we could finally 230 track lifetimes of multi-word registers accessed via subregs. */ 231}; 232 233/* For use in communicating between propagate_block and its subroutines. 234 Holds all information needed to compute life and def-use information. */ 235 236struct propagate_block_info 237{ 238 /* The basic block we're considering. */ 239 basic_block bb; 240 241 /* Bit N is set if register N is conditionally or unconditionally live. */ 242 regset reg_live; 243 244 /* Bit N is set if register N is set this insn. */ 245 regset new_set; 246 247 /* Element N is the next insn that uses (hard or pseudo) register N 248 within the current basic block; or zero, if there is no such insn. */ 249 rtx *reg_next_use; 250 251 /* Contains a list of all the MEMs we are tracking for dead store 252 elimination. */ 253 rtx mem_set_list; 254 255 /* If non-null, record the set of registers set unconditionally in the 256 basic block. */ 257 regset local_set; 258 259 /* If non-null, record the set of registers set conditionally in the 260 basic block. */ 261 regset cond_local_set; 262 263#ifdef HAVE_conditional_execution 264 /* Indexed by register number, holds a reg_cond_life_info for each 265 register that is not unconditionally live or dead. */ 266 splay_tree reg_cond_dead; 267 268 /* Bit N is set if register N is in an expression in reg_cond_dead. */ 269 regset reg_cond_reg; 270#endif 271 272 /* The length of mem_set_list. */ 273 int mem_set_list_len; 274 275 /* Non-zero if the value of CC0 is live. */ 276 int cc0_live; 277 278 /* Flags controling the set of information propagate_block collects. */ 279 int flags; 280}; 281 282/* Maximum length of pbi->mem_set_list before we start dropping 283 new elements on the floor. */ 284#define MAX_MEM_SET_LIST_LEN 100 285 286/* Forward declarations */ 287static int verify_wide_reg_1 PARAMS ((rtx *, void *)); 288static void verify_wide_reg PARAMS ((int, basic_block)); 289static void verify_local_live_at_start PARAMS ((regset, basic_block)); 290static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *)); 291static void notice_stack_pointer_modification PARAMS ((rtx)); 292static void mark_reg PARAMS ((rtx, void *)); 293static void mark_regs_live_at_end PARAMS ((regset)); 294static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *)); 295static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int)); 296static void propagate_block_delete_insn PARAMS ((basic_block, rtx)); 297static rtx propagate_block_delete_libcall PARAMS ((rtx, rtx)); 298static int insn_dead_p PARAMS ((struct propagate_block_info *, 299 rtx, int, rtx)); 300static int libcall_dead_p PARAMS ((struct propagate_block_info *, 301 rtx, rtx)); 302static void mark_set_regs PARAMS ((struct propagate_block_info *, 303 rtx, rtx)); 304static void mark_set_1 PARAMS ((struct propagate_block_info *, 305 enum rtx_code, rtx, rtx, 306 rtx, int)); 307static int find_regno_partial PARAMS ((rtx *, void *)); 308 309#ifdef HAVE_conditional_execution 310static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *, 311 int, rtx)); 312static void free_reg_cond_life_info PARAMS ((splay_tree_value)); 313static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *)); 314static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *, 315 int)); 316static rtx elim_reg_cond PARAMS ((rtx, unsigned int)); 317static rtx ior_reg_cond PARAMS ((rtx, rtx, int)); 318static rtx not_reg_cond PARAMS ((rtx)); 319static rtx and_reg_cond PARAMS ((rtx, rtx, int)); 320#endif 321#ifdef AUTO_INC_DEC 322static void attempt_auto_inc PARAMS ((struct propagate_block_info *, 323 rtx, rtx, rtx, rtx, rtx)); 324static void find_auto_inc PARAMS ((struct propagate_block_info *, 325 rtx, rtx)); 326static int try_pre_increment_1 PARAMS ((struct propagate_block_info *, 327 rtx)); 328static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT)); 329#endif 330static void mark_used_reg PARAMS ((struct propagate_block_info *, 331 rtx, rtx, rtx)); 332static void mark_used_regs PARAMS ((struct propagate_block_info *, 333 rtx, rtx, rtx)); 334void dump_flow_info PARAMS ((FILE *)); 335void debug_flow_info PARAMS ((void)); 336static void add_to_mem_set_list PARAMS ((struct propagate_block_info *, 337 rtx)); 338static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *, 339 rtx)); 340static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *, 341 rtx)); 342static void delete_dead_jumptables PARAMS ((void)); 343static void clear_log_links PARAMS ((sbitmap)); 344 345 346void 347check_function_return_warnings () 348{ 349 if (warn_missing_noreturn 350 && !TREE_THIS_VOLATILE (cfun->decl) 351 && EXIT_BLOCK_PTR->pred == NULL 352 && (lang_missing_noreturn_ok_p 353 && !lang_missing_noreturn_ok_p (cfun->decl))) 354 warning ("function might be possible candidate for attribute `noreturn'"); 355 356 /* If we have a path to EXIT, then we do return. */ 357 if (TREE_THIS_VOLATILE (cfun->decl) 358 && EXIT_BLOCK_PTR->pred != NULL) 359 warning ("`noreturn' function does return"); 360 361 /* If the clobber_return_insn appears in some basic block, then we 362 do reach the end without returning a value. */ 363 else if (warn_return_type 364 && cfun->x_clobber_return_insn != NULL 365 && EXIT_BLOCK_PTR->pred != NULL) 366 { 367 int max_uid = get_max_uid (); 368 369 /* If clobber_return_insn was excised by jump1, then renumber_insns 370 can make max_uid smaller than the number still recorded in our rtx. 371 That's fine, since this is a quick way of verifying that the insn 372 is no longer in the chain. */ 373 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid) 374 { 375 /* Recompute insn->block mapping, since the initial mapping is 376 set before we delete unreachable blocks. */ 377 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL) 378 warning ("control reaches end of non-void function"); 379 } 380 } 381} 382 383/* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK 384 note associated with the BLOCK. */ 385 386rtx 387first_insn_after_basic_block_note (block) 388 basic_block block; 389{ 390 rtx insn; 391 392 /* Get the first instruction in the block. */ 393 insn = block->head; 394 395 if (insn == NULL_RTX) 396 return NULL_RTX; 397 if (GET_CODE (insn) == CODE_LABEL) 398 insn = NEXT_INSN (insn); 399 if (!NOTE_INSN_BASIC_BLOCK_P (insn)) 400 abort (); 401 402 return NEXT_INSN (insn); 403} 404 405/* Perform data flow analysis. 406 F is the first insn of the function; FLAGS is a set of PROP_* flags 407 to be used in accumulating flow info. */ 408 409void 410life_analysis (f, file, flags) 411 rtx f; 412 FILE *file; 413 int flags; 414{ 415#ifdef ELIMINABLE_REGS 416 int i; 417 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS; 418#endif 419 420 /* Record which registers will be eliminated. We use this in 421 mark_used_regs. */ 422 423 CLEAR_HARD_REG_SET (elim_reg_set); 424 425#ifdef ELIMINABLE_REGS 426 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++) 427 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from); 428#else 429 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM); 430#endif 431 432 if (! optimize) 433 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES); 434 435 /* The post-reload life analysis have (on a global basis) the same 436 registers live as was computed by reload itself. elimination 437 Otherwise offsets and such may be incorrect. 438 439 Reload will make some registers as live even though they do not 440 appear in the rtl. 441 442 We don't want to create new auto-incs after reload, since they 443 are unlikely to be useful and can cause problems with shared 444 stack slots. */ 445 if (reload_completed) 446 flags &= ~(PROP_REG_INFO | PROP_AUTOINC); 447 448 /* We want alias analysis information for local dead store elimination. */ 449 if (optimize && (flags & PROP_SCAN_DEAD_CODE)) 450 init_alias_analysis (); 451 452 /* Always remove no-op moves. Do this before other processing so 453 that we don't have to keep re-scanning them. */ 454 delete_noop_moves (f); 455 purge_all_dead_edges (false); 456 457 /* Some targets can emit simpler epilogues if they know that sp was 458 not ever modified during the function. After reload, of course, 459 we've already emitted the epilogue so there's no sense searching. */ 460 if (! reload_completed) 461 notice_stack_pointer_modification (f); 462 463 /* Allocate and zero out data structures that will record the 464 data from lifetime analysis. */ 465 allocate_reg_life_data (); 466 allocate_bb_life_data (); 467 468 /* Find the set of registers live on function exit. */ 469 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start); 470 471 /* "Update" life info from zero. It'd be nice to begin the 472 relaxation with just the exit and noreturn blocks, but that set 473 is not immediately handy. */ 474 475 if (flags & PROP_REG_INFO) 476 memset (regs_ever_live, 0, sizeof (regs_ever_live)); 477 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags); 478 479 /* Clean up. */ 480 if (optimize && (flags & PROP_SCAN_DEAD_CODE)) 481 end_alias_analysis (); 482 483 if (file) 484 dump_flow_info (file); 485 486 free_basic_block_vars (1); 487 488#ifdef ENABLE_CHECKING 489 { 490 rtx insn; 491 492 /* Search for any REG_LABEL notes which reference deleted labels. */ 493 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) 494 { 495 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX); 496 497 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL) 498 abort (); 499 } 500 } 501#endif 502 /* Removing dead insns should've made jumptables really dead. */ 503 delete_dead_jumptables (); 504} 505 506/* A subroutine of verify_wide_reg, called through for_each_rtx. 507 Search for REGNO. If found, return 2 if it is not wider than 508 word_mode. */ 509 510static int 511verify_wide_reg_1 (px, pregno) 512 rtx *px; 513 void *pregno; 514{ 515 rtx x = *px; 516 unsigned int regno = *(int *) pregno; 517 518 if (GET_CODE (x) == REG && REGNO (x) == regno) 519 { 520 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD) 521 return 2; 522 return 1; 523 } 524 return 0; 525} 526 527/* A subroutine of verify_local_live_at_start. Search through insns 528 of BB looking for register REGNO. */ 529 530static void 531verify_wide_reg (regno, bb) 532 int regno; 533 basic_block bb; 534{ 535 rtx head = bb->head, end = bb->end; 536 537 while (1) 538 { 539 if (INSN_P (head)) 540 { 541 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no); 542 if (r == 1) 543 return; 544 if (r == 2) 545 break; 546 } 547 if (head == end) 548 break; 549 head = NEXT_INSN (head); 550 } 551 552 if (rtl_dump_file) 553 { 554 fprintf (rtl_dump_file, "Register %d died unexpectedly.\n", regno); 555 dump_bb (bb, rtl_dump_file); 556 } 557 abort (); 558} 559 560/* A subroutine of update_life_info. Verify that there are no untoward 561 changes in live_at_start during a local update. */ 562 563static void 564verify_local_live_at_start (new_live_at_start, bb) 565 regset new_live_at_start; 566 basic_block bb; 567{ 568 if (reload_completed) 569 { 570 /* After reload, there are no pseudos, nor subregs of multi-word 571 registers. The regsets should exactly match. */ 572 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start)) 573 { 574 if (rtl_dump_file) 575 { 576 fprintf (rtl_dump_file, 577 "live_at_start mismatch in bb %d, aborting\nNew:\n", 578 bb->index); 579 debug_bitmap_file (rtl_dump_file, new_live_at_start); 580 fputs ("Old:\n", rtl_dump_file); 581 dump_bb (bb, rtl_dump_file); 582 } 583 abort (); 584 } 585 } 586 else 587 { 588 int i; 589 590 /* Find the set of changed registers. */ 591 XOR_REG_SET (new_live_at_start, bb->global_live_at_start); 592 593 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i, 594 { 595 /* No registers should die. */ 596 if (REGNO_REG_SET_P (bb->global_live_at_start, i)) 597 { 598 if (rtl_dump_file) 599 { 600 fprintf (rtl_dump_file, 601 "Register %d died unexpectedly.\n", i); 602 dump_bb (bb, rtl_dump_file); 603 } 604 abort (); 605 } 606 607 /* Verify that the now-live register is wider than word_mode. */ 608 verify_wide_reg (i, bb); 609 }); 610 } 611} 612 613/* Updates life information starting with the basic blocks set in BLOCKS. 614 If BLOCKS is null, consider it to be the universal set. 615 616 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing, 617 we are only expecting local modifications to basic blocks. If we find 618 extra registers live at the beginning of a block, then we either killed 619 useful data, or we have a broken split that wants data not provided. 620 If we find registers removed from live_at_start, that means we have 621 a broken peephole that is killing a register it shouldn't. 622 623 ??? This is not true in one situation -- when a pre-reload splitter 624 generates subregs of a multi-word pseudo, current life analysis will 625 lose the kill. So we _can_ have a pseudo go live. How irritating. 626 627 Including PROP_REG_INFO does not properly refresh regs_ever_live 628 unless the caller resets it to zero. */ 629 630void 631update_life_info (blocks, extent, prop_flags) 632 sbitmap blocks; 633 enum update_life_extent extent; 634 int prop_flags; 635{ 636 regset tmp; 637 regset_head tmp_head; 638 int i; 639 int stabilized_prop_flags = prop_flags; 640 641 tmp = INITIALIZE_REG_SET (tmp_head); 642 643 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks) 644 ? TV_LIFE_UPDATE : TV_LIFE); 645 646 /* Changes to the CFG are only allowed when 647 doing a global update for the entire CFG. */ 648 if ((prop_flags & PROP_ALLOW_CFG_CHANGES) 649 && (extent == UPDATE_LIFE_LOCAL || blocks)) 650 abort (); 651 652 /* Clear log links in case we are asked to (re)compute them. */ 653 if (prop_flags & PROP_LOG_LINKS) 654 clear_log_links (blocks); 655 656 /* For a global update, we go through the relaxation process again. */ 657 if (extent != UPDATE_LIFE_LOCAL) 658 { 659 for ( ; ; ) 660 { 661 int changed = 0; 662 663 calculate_global_regs_live (blocks, blocks, 664 prop_flags & (PROP_SCAN_DEAD_CODE 665 | PROP_ALLOW_CFG_CHANGES)); 666 667 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES)) 668 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES)) 669 break; 670 671 /* Removing dead code may allow the CFG to be simplified which 672 in turn may allow for further dead code detection / removal. */ 673 for (i = n_basic_blocks - 1; i >= 0; --i) 674 { 675 basic_block bb = BASIC_BLOCK (i); 676 677 COPY_REG_SET (tmp, bb->global_live_at_end); 678 changed |= propagate_block (bb, tmp, NULL, NULL, 679 prop_flags & (PROP_SCAN_DEAD_CODE 680 | PROP_KILL_DEAD_CODE)); 681 } 682 683 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to 684 subsequent propagate_block calls, since removing or acting as 685 removing dead code can affect global register liveness, which 686 is supposed to be finalized for this call after this loop. */ 687 stabilized_prop_flags 688 &= ~(PROP_SCAN_DEAD_CODE | PROP_KILL_DEAD_CODE); 689 690 if (! changed) 691 break; 692 693 /* We repeat regardless of what cleanup_cfg says. If there were 694 instructions deleted above, that might have been only a 695 partial improvement (see MAX_MEM_SET_LIST_LEN usage). 696 Further improvement may be possible. */ 697 cleanup_cfg (CLEANUP_EXPENSIVE); 698 } 699 700 /* If asked, remove notes from the blocks we'll update. */ 701 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES) 702 count_or_remove_death_notes (blocks, 1); 703 } 704 705 if (blocks) 706 { 707 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i, 708 { 709 basic_block bb = BASIC_BLOCK (i); 710 711 COPY_REG_SET (tmp, bb->global_live_at_end); 712 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags); 713 714 if (extent == UPDATE_LIFE_LOCAL) 715 verify_local_live_at_start (tmp, bb); 716 }); 717 } 718 else 719 { 720 for (i = n_basic_blocks - 1; i >= 0; --i) 721 { 722 basic_block bb = BASIC_BLOCK (i); 723 724 COPY_REG_SET (tmp, bb->global_live_at_end); 725 726 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags); 727 728 if (extent == UPDATE_LIFE_LOCAL) 729 verify_local_live_at_start (tmp, bb); 730 } 731 } 732 733 FREE_REG_SET (tmp); 734 735 if (prop_flags & PROP_REG_INFO) 736 { 737 /* The only pseudos that are live at the beginning of the function 738 are those that were not set anywhere in the function. local-alloc 739 doesn't know how to handle these correctly, so mark them as not 740 local to any one basic block. */ 741 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end, 742 FIRST_PSEUDO_REGISTER, i, 743 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; }); 744 745 /* We have a problem with any pseudoreg that lives across the setjmp. 746 ANSI says that if a user variable does not change in value between 747 the setjmp and the longjmp, then the longjmp preserves it. This 748 includes longjmp from a place where the pseudo appears dead. 749 (In principle, the value still exists if it is in scope.) 750 If the pseudo goes in a hard reg, some other value may occupy 751 that hard reg where this pseudo is dead, thus clobbering the pseudo. 752 Conclusion: such a pseudo must not go in a hard reg. */ 753 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp, 754 FIRST_PSEUDO_REGISTER, i, 755 { 756 if (regno_reg_rtx[i] != 0) 757 { 758 REG_LIVE_LENGTH (i) = -1; 759 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN; 760 } 761 }); 762 } 763 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks) 764 ? TV_LIFE_UPDATE : TV_LIFE); 765} 766 767/* Free the variables allocated by find_basic_blocks. 768 769 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */ 770 771void 772free_basic_block_vars (keep_head_end_p) 773 int keep_head_end_p; 774{ 775 if (! keep_head_end_p) 776 { 777 if (basic_block_info) 778 { 779 clear_edges (); 780 VARRAY_FREE (basic_block_info); 781 } 782 n_basic_blocks = 0; 783 784 ENTRY_BLOCK_PTR->aux = NULL; 785 ENTRY_BLOCK_PTR->global_live_at_end = NULL; 786 EXIT_BLOCK_PTR->aux = NULL; 787 EXIT_BLOCK_PTR->global_live_at_start = NULL; 788 } 789} 790 791/* Delete any insns that copy a register to itself. */ 792 793void 794delete_noop_moves (f) 795 rtx f ATTRIBUTE_UNUSED; 796{ 797 int i; 798 rtx insn, next; 799 basic_block bb; 800 801 for (i = 0; i < n_basic_blocks; i++) 802 { 803 bb = BASIC_BLOCK (i); 804 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next) 805 { 806 next = NEXT_INSN (insn); 807 if (INSN_P (insn) && noop_move_p (insn)) 808 { 809 rtx note; 810 811 /* If we're about to remove the first insn of a libcall 812 then move the libcall note to the next real insn and 813 update the retval note. */ 814 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX)) 815 && XEXP (note, 0) != insn) 816 { 817 rtx new_libcall_insn = next_real_insn (insn); 818 rtx retval_note = find_reg_note (XEXP (note, 0), 819 REG_RETVAL, NULL_RTX); 820 REG_NOTES (new_libcall_insn) 821 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0), 822 REG_NOTES (new_libcall_insn)); 823 XEXP (retval_note, 0) = new_libcall_insn; 824 } 825 826 /* Do not call delete_insn here since that may change 827 the basic block boundaries which upsets some callers. */ 828 PUT_CODE (insn, NOTE); 829 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED; 830 NOTE_SOURCE_FILE (insn) = 0; 831 } 832 } 833 } 834} 835 836/* Delete any jump tables never referenced. We can't delete them at the 837 time of removing tablejump insn as they are referenced by the preceding 838 insns computing the destination, so we delay deleting and garbagecollect 839 them once life information is computed. */ 840static void 841delete_dead_jumptables () 842{ 843 rtx insn, next; 844 for (insn = get_insns (); insn; insn = next) 845 { 846 next = NEXT_INSN (insn); 847 if (GET_CODE (insn) == CODE_LABEL 848 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn) 849 && GET_CODE (next) == JUMP_INSN 850 && (GET_CODE (PATTERN (next)) == ADDR_VEC 851 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) 852 { 853 if (rtl_dump_file) 854 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn)); 855 delete_insn (NEXT_INSN (insn)); 856 delete_insn (insn); 857 next = NEXT_INSN (next); 858 } 859 } 860} 861 862/* Determine if the stack pointer is constant over the life of the function. 863 Only useful before prologues have been emitted. */ 864 865static void 866notice_stack_pointer_modification_1 (x, pat, data) 867 rtx x; 868 rtx pat ATTRIBUTE_UNUSED; 869 void *data ATTRIBUTE_UNUSED; 870{ 871 if (x == stack_pointer_rtx 872 /* The stack pointer is only modified indirectly as the result 873 of a push until later in flow. See the comments in rtl.texi 874 regarding Embedded Side-Effects on Addresses. */ 875 || (GET_CODE (x) == MEM 876 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a' 877 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx)) 878 current_function_sp_is_unchanging = 0; 879} 880 881static void 882notice_stack_pointer_modification (f) 883 rtx f; 884{ 885 rtx insn; 886 887 /* Assume that the stack pointer is unchanging if alloca hasn't 888 been used. */ 889 current_function_sp_is_unchanging = !current_function_calls_alloca; 890 if (! current_function_sp_is_unchanging) 891 return; 892 893 for (insn = f; insn; insn = NEXT_INSN (insn)) 894 { 895 if (INSN_P (insn)) 896 { 897 /* Check if insn modifies the stack pointer. */ 898 note_stores (PATTERN (insn), notice_stack_pointer_modification_1, 899 NULL); 900 if (! current_function_sp_is_unchanging) 901 return; 902 } 903 } 904} 905 906/* Mark a register in SET. Hard registers in large modes get all 907 of their component registers set as well. */ 908 909static void 910mark_reg (reg, xset) 911 rtx reg; 912 void *xset; 913{ 914 regset set = (regset) xset; 915 int regno = REGNO (reg); 916 917 if (GET_MODE (reg) == BLKmode) 918 abort (); 919 920 SET_REGNO_REG_SET (set, regno); 921 if (regno < FIRST_PSEUDO_REGISTER) 922 { 923 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); 924 while (--n > 0) 925 SET_REGNO_REG_SET (set, regno + n); 926 } 927} 928 929/* Mark those regs which are needed at the end of the function as live 930 at the end of the last basic block. */ 931 932static void 933mark_regs_live_at_end (set) 934 regset set; 935{ 936 unsigned int i; 937 938 /* If exiting needs the right stack value, consider the stack pointer 939 live at the end of the function. */ 940 if ((HAVE_epilogue && reload_completed) 941 || ! EXIT_IGNORE_STACK 942 || (! FRAME_POINTER_REQUIRED 943 && ! current_function_calls_alloca 944 && flag_omit_frame_pointer) 945 || current_function_sp_is_unchanging) 946 { 947 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM); 948 } 949 950 /* Mark the frame pointer if needed at the end of the function. If 951 we end up eliminating it, it will be removed from the live list 952 of each basic block by reload. */ 953 954 if (! reload_completed || frame_pointer_needed) 955 { 956 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM); 957#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 958 /* If they are different, also mark the hard frame pointer as live. */ 959 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM)) 960 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM); 961#endif 962 } 963 964#ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED 965 /* Many architectures have a GP register even without flag_pic. 966 Assume the pic register is not in use, or will be handled by 967 other means, if it is not fixed. */ 968 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM 969 && fixed_regs[PIC_OFFSET_TABLE_REGNUM]) 970 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM); 971#endif 972 973 /* Mark all global registers, and all registers used by the epilogue 974 as being live at the end of the function since they may be 975 referenced by our caller. */ 976 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 977 if (global_regs[i] || EPILOGUE_USES (i)) 978 SET_REGNO_REG_SET (set, i); 979 980 if (HAVE_epilogue && reload_completed) 981 { 982 /* Mark all call-saved registers that we actually used. */ 983 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 984 if (regs_ever_live[i] && ! LOCAL_REGNO (i) 985 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) 986 SET_REGNO_REG_SET (set, i); 987 } 988 989#ifdef EH_RETURN_DATA_REGNO 990 /* Mark the registers that will contain data for the handler. */ 991 if (reload_completed && current_function_calls_eh_return) 992 for (i = 0; ; ++i) 993 { 994 unsigned regno = EH_RETURN_DATA_REGNO(i); 995 if (regno == INVALID_REGNUM) 996 break; 997 SET_REGNO_REG_SET (set, regno); 998 } 999#endif 1000#ifdef EH_RETURN_STACKADJ_RTX 1001 if ((! HAVE_epilogue || ! reload_completed) 1002 && current_function_calls_eh_return) 1003 { 1004 rtx tmp = EH_RETURN_STACKADJ_RTX; 1005 if (tmp && REG_P (tmp)) 1006 mark_reg (tmp, set); 1007 } 1008#endif 1009#ifdef EH_RETURN_HANDLER_RTX 1010 if ((! HAVE_epilogue || ! reload_completed) 1011 && current_function_calls_eh_return) 1012 { 1013 rtx tmp = EH_RETURN_HANDLER_RTX; 1014 if (tmp && REG_P (tmp)) 1015 mark_reg (tmp, set); 1016 } 1017#endif 1018 1019 /* Mark function return value. */ 1020 diddle_return_value (mark_reg, set); 1021} 1022 1023/* Callback function for for_each_successor_phi. DATA is a regset. 1024 Sets the SRC_REGNO, the regno of the phi alternative for phi node 1025 INSN, in the regset. */ 1026 1027static int 1028set_phi_alternative_reg (insn, dest_regno, src_regno, data) 1029 rtx insn ATTRIBUTE_UNUSED; 1030 int dest_regno ATTRIBUTE_UNUSED; 1031 int src_regno; 1032 void *data; 1033{ 1034 regset live = (regset) data; 1035 SET_REGNO_REG_SET (live, src_regno); 1036 return 0; 1037} 1038 1039/* Propagate global life info around the graph of basic blocks. Begin 1040 considering blocks with their corresponding bit set in BLOCKS_IN. 1041 If BLOCKS_IN is null, consider it the universal set. 1042 1043 BLOCKS_OUT is set for every block that was changed. */ 1044 1045static void 1046calculate_global_regs_live (blocks_in, blocks_out, flags) 1047 sbitmap blocks_in, blocks_out; 1048 int flags; 1049{ 1050 basic_block *queue, *qhead, *qtail, *qend; 1051 regset tmp, new_live_at_end, call_used; 1052 regset_head tmp_head, call_used_head; 1053 regset_head new_live_at_end_head; 1054 int i; 1055 1056 tmp = INITIALIZE_REG_SET (tmp_head); 1057 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head); 1058 call_used = INITIALIZE_REG_SET (call_used_head); 1059 1060 /* Inconveniently, this is only readily available in hard reg set form. */ 1061 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) 1062 if (call_used_regs[i]) 1063 SET_REGNO_REG_SET (call_used, i); 1064 1065 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one 1066 because the `head == tail' style test for an empty queue doesn't 1067 work with a full queue. */ 1068 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue)); 1069 qtail = queue; 1070 qhead = qend = queue + n_basic_blocks + 2; 1071 1072 /* Queue the blocks set in the initial mask. Do this in reverse block 1073 number order so that we are more likely for the first round to do 1074 useful work. We use AUX non-null to flag that the block is queued. */ 1075 if (blocks_in) 1076 { 1077 /* Clear out the garbage that might be hanging out in bb->aux. */ 1078 for (i = n_basic_blocks - 1; i >= 0; --i) 1079 BASIC_BLOCK (i)->aux = NULL; 1080 1081 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i, 1082 { 1083 basic_block bb = BASIC_BLOCK (i); 1084 *--qhead = bb; 1085 bb->aux = bb; 1086 }); 1087 } 1088 else 1089 { 1090 for (i = 0; i < n_basic_blocks; ++i) 1091 { 1092 basic_block bb = BASIC_BLOCK (i); 1093 *--qhead = bb; 1094 bb->aux = bb; 1095 } 1096 } 1097 1098 /* We clean aux when we remove the initially-enqueued bbs, but we 1099 don't enqueue ENTRY and EXIT initially, so clean them upfront and 1100 unconditionally. */ 1101 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL; 1102 1103 if (blocks_out) 1104 sbitmap_zero (blocks_out); 1105 1106 /* We work through the queue until there are no more blocks. What 1107 is live at the end of this block is precisely the union of what 1108 is live at the beginning of all its successors. So, we set its 1109 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field 1110 for its successors. Then, we compute GLOBAL_LIVE_AT_START for 1111 this block by walking through the instructions in this block in 1112 reverse order and updating as we go. If that changed 1113 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the 1114 queue; they will now need to recalculate GLOBAL_LIVE_AT_END. 1115 1116 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START 1117 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it 1118 must either be live at the end of the block, or used within the 1119 block. In the latter case, it will certainly never disappear 1120 from GLOBAL_LIVE_AT_START. In the former case, the register 1121 could go away only if it disappeared from GLOBAL_LIVE_AT_START 1122 for one of the successor blocks. By induction, that cannot 1123 occur. */ 1124 while (qhead != qtail) 1125 { 1126 int rescan, changed; 1127 basic_block bb; 1128 edge e; 1129 1130 bb = *qhead++; 1131 if (qhead == qend) 1132 qhead = queue; 1133 bb->aux = NULL; 1134 1135 /* Begin by propagating live_at_start from the successor blocks. */ 1136 CLEAR_REG_SET (new_live_at_end); 1137 1138 if (bb->succ) 1139 for (e = bb->succ; e; e = e->succ_next) 1140 { 1141 basic_block sb = e->dest; 1142 1143 /* Call-clobbered registers die across exception and 1144 call edges. */ 1145 /* ??? Abnormal call edges ignored for the moment, as this gets 1146 confused by sibling call edges, which crashes reg-stack. */ 1147 if (e->flags & EDGE_EH) 1148 { 1149 bitmap_operation (tmp, sb->global_live_at_start, 1150 call_used, BITMAP_AND_COMPL); 1151 IOR_REG_SET (new_live_at_end, tmp); 1152 } 1153 else 1154 IOR_REG_SET (new_live_at_end, sb->global_live_at_start); 1155 1156 /* If a target saves one register in another (instead of on 1157 the stack) the save register will need to be live for EH. */ 1158 if (e->flags & EDGE_EH) 1159 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1160 if (EH_USES (i)) 1161 SET_REGNO_REG_SET (new_live_at_end, i); 1162 } 1163 else 1164 { 1165 /* This might be a noreturn function that throws. And 1166 even if it isn't, getting the unwind info right helps 1167 debugging. */ 1168 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1169 if (EH_USES (i)) 1170 SET_REGNO_REG_SET (new_live_at_end, i); 1171 } 1172 1173 /* The all-important stack pointer must always be live. */ 1174 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM); 1175 1176 /* Before reload, there are a few registers that must be forced 1177 live everywhere -- which might not already be the case for 1178 blocks within infinite loops. */ 1179 if (! reload_completed) 1180 { 1181 /* Any reference to any pseudo before reload is a potential 1182 reference of the frame pointer. */ 1183 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM); 1184 1185#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 1186 /* Pseudos with argument area equivalences may require 1187 reloading via the argument pointer. */ 1188 if (fixed_regs[ARG_POINTER_REGNUM]) 1189 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM); 1190#endif 1191 1192 /* Any constant, or pseudo with constant equivalences, may 1193 require reloading from memory using the pic register. */ 1194 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM 1195 && fixed_regs[PIC_OFFSET_TABLE_REGNUM]) 1196 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM); 1197 } 1198 1199 /* Regs used in phi nodes are not included in 1200 global_live_at_start, since they are live only along a 1201 particular edge. Set those regs that are live because of a 1202 phi node alternative corresponding to this particular block. */ 1203 if (in_ssa_form) 1204 for_each_successor_phi (bb, &set_phi_alternative_reg, 1205 new_live_at_end); 1206 1207 if (bb == ENTRY_BLOCK_PTR) 1208 { 1209 COPY_REG_SET (bb->global_live_at_end, new_live_at_end); 1210 continue; 1211 } 1212 1213 /* On our first pass through this block, we'll go ahead and continue. 1214 Recognize first pass by local_set NULL. On subsequent passes, we 1215 get to skip out early if live_at_end wouldn't have changed. */ 1216 1217 if (bb->local_set == NULL) 1218 { 1219 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1220 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1221 rescan = 1; 1222 } 1223 else 1224 { 1225 /* If any bits were removed from live_at_end, we'll have to 1226 rescan the block. This wouldn't be necessary if we had 1227 precalculated local_live, however with PROP_SCAN_DEAD_CODE 1228 local_live is really dependent on live_at_end. */ 1229 CLEAR_REG_SET (tmp); 1230 rescan = bitmap_operation (tmp, bb->global_live_at_end, 1231 new_live_at_end, BITMAP_AND_COMPL); 1232 1233 if (! rescan) 1234 { 1235 /* If any of the registers in the new live_at_end set are 1236 conditionally set in this basic block, we must rescan. 1237 This is because conditional lifetimes at the end of the 1238 block do not just take the live_at_end set into account, 1239 but also the liveness at the start of each successor 1240 block. We can miss changes in those sets if we only 1241 compare the new live_at_end against the previous one. */ 1242 CLEAR_REG_SET (tmp); 1243 rescan = bitmap_operation (tmp, new_live_at_end, 1244 bb->cond_local_set, BITMAP_AND); 1245 } 1246 1247 if (! rescan) 1248 { 1249 /* Find the set of changed bits. Take this opportunity 1250 to notice that this set is empty and early out. */ 1251 CLEAR_REG_SET (tmp); 1252 changed = bitmap_operation (tmp, bb->global_live_at_end, 1253 new_live_at_end, BITMAP_XOR); 1254 if (! changed) 1255 continue; 1256 1257 /* If any of the changed bits overlap with local_set, 1258 we'll have to rescan the block. Detect overlap by 1259 the AND with ~local_set turning off bits. */ 1260 rescan = bitmap_operation (tmp, tmp, bb->local_set, 1261 BITMAP_AND_COMPL); 1262 } 1263 } 1264 1265 /* Let our caller know that BB changed enough to require its 1266 death notes updated. */ 1267 if (blocks_out) 1268 SET_BIT (blocks_out, bb->index); 1269 1270 if (! rescan) 1271 { 1272 /* Add to live_at_start the set of all registers in 1273 new_live_at_end that aren't in the old live_at_end. */ 1274 1275 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end, 1276 BITMAP_AND_COMPL); 1277 COPY_REG_SET (bb->global_live_at_end, new_live_at_end); 1278 1279 changed = bitmap_operation (bb->global_live_at_start, 1280 bb->global_live_at_start, 1281 tmp, BITMAP_IOR); 1282 if (! changed) 1283 continue; 1284 } 1285 else 1286 { 1287 COPY_REG_SET (bb->global_live_at_end, new_live_at_end); 1288 1289 /* Rescan the block insn by insn to turn (a copy of) live_at_end 1290 into live_at_start. */ 1291 propagate_block (bb, new_live_at_end, bb->local_set, 1292 bb->cond_local_set, flags); 1293 1294 /* If live_at start didn't change, no need to go farther. */ 1295 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end)) 1296 continue; 1297 1298 COPY_REG_SET (bb->global_live_at_start, new_live_at_end); 1299 } 1300 1301 /* Queue all predecessors of BB so that we may re-examine 1302 their live_at_end. */ 1303 for (e = bb->pred; e; e = e->pred_next) 1304 { 1305 basic_block pb = e->src; 1306 if (pb->aux == NULL) 1307 { 1308 *qtail++ = pb; 1309 if (qtail == qend) 1310 qtail = queue; 1311 pb->aux = pb; 1312 } 1313 } 1314 } 1315 1316 FREE_REG_SET (tmp); 1317 FREE_REG_SET (new_live_at_end); 1318 FREE_REG_SET (call_used); 1319 1320 if (blocks_out) 1321 { 1322 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i, 1323 { 1324 basic_block bb = BASIC_BLOCK (i); 1325 FREE_REG_SET (bb->local_set); 1326 FREE_REG_SET (bb->cond_local_set); 1327 }); 1328 } 1329 else 1330 { 1331 for (i = n_basic_blocks - 1; i >= 0; --i) 1332 { 1333 basic_block bb = BASIC_BLOCK (i); 1334 FREE_REG_SET (bb->local_set); 1335 FREE_REG_SET (bb->cond_local_set); 1336 } 1337 } 1338 1339 free (queue); 1340} 1341 1342 1343/* This structure is used to pass parameters to an from the 1344 the function find_regno_partial(). It is used to pass in the 1345 register number we are looking, as well as to return any rtx 1346 we find. */ 1347 1348typedef struct { 1349 unsigned regno_to_find; 1350 rtx retval; 1351} find_regno_partial_param; 1352 1353 1354/* Find the rtx for the reg numbers specified in 'data' if it is 1355 part of an expression which only uses part of the register. Return 1356 it in the structure passed in. */ 1357static int 1358find_regno_partial (ptr, data) 1359 rtx *ptr; 1360 void *data; 1361{ 1362 find_regno_partial_param *param = (find_regno_partial_param *)data; 1363 unsigned reg = param->regno_to_find; 1364 param->retval = NULL_RTX; 1365 1366 if (*ptr == NULL_RTX) 1367 return 0; 1368 1369 switch (GET_CODE (*ptr)) 1370 { 1371 case ZERO_EXTRACT: 1372 case SIGN_EXTRACT: 1373 case STRICT_LOW_PART: 1374 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg) 1375 { 1376 param->retval = XEXP (*ptr, 0); 1377 return 1; 1378 } 1379 break; 1380 1381 case SUBREG: 1382 if (GET_CODE (SUBREG_REG (*ptr)) == REG 1383 && REGNO (SUBREG_REG (*ptr)) == reg) 1384 { 1385 param->retval = SUBREG_REG (*ptr); 1386 return 1; 1387 } 1388 break; 1389 1390 default: 1391 break; 1392 } 1393 1394 return 0; 1395} 1396 1397/* Process all immediate successors of the entry block looking for pseudo 1398 registers which are live on entry. Find all of those whose first 1399 instance is a partial register reference of some kind, and initialize 1400 them to 0 after the entry block. This will prevent bit sets within 1401 registers whose value is unknown, and may contain some kind of sticky 1402 bits we don't want. */ 1403 1404int 1405initialize_uninitialized_subregs () 1406{ 1407 rtx insn; 1408 edge e; 1409 int reg, did_something = 0; 1410 find_regno_partial_param param; 1411 1412 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) 1413 { 1414 basic_block bb = e->dest; 1415 regset map = bb->global_live_at_start; 1416 EXECUTE_IF_SET_IN_REG_SET (map, 1417 FIRST_PSEUDO_REGISTER, reg, 1418 { 1419 int uid = REGNO_FIRST_UID (reg); 1420 rtx i; 1421 1422 /* Find an insn which mentions the register we are looking for. 1423 Its preferable to have an instance of the register's rtl since 1424 there may be various flags set which we need to duplicate. 1425 If we can't find it, its probably an automatic whose initial 1426 value doesn't matter, or hopefully something we don't care about. */ 1427 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i)) 1428 ; 1429 if (i != NULL_RTX) 1430 { 1431 /* Found the insn, now get the REG rtx, if we can. */ 1432 param.regno_to_find = reg; 1433 for_each_rtx (&i, find_regno_partial, ¶m); 1434 if (param.retval != NULL_RTX) 1435 { 1436 insn = gen_move_insn (param.retval, 1437 CONST0_RTX (GET_MODE (param.retval))); 1438 insert_insn_on_edge (insn, e); 1439 did_something = 1; 1440 } 1441 } 1442 }); 1443 } 1444 1445 if (did_something) 1446 commit_edge_insertions (); 1447 return did_something; 1448} 1449 1450 1451/* Subroutines of life analysis. */ 1452 1453/* Allocate the permanent data structures that represent the results 1454 of life analysis. Not static since used also for stupid life analysis. */ 1455 1456void 1457allocate_bb_life_data () 1458{ 1459 int i; 1460 1461 for (i = 0; i < n_basic_blocks; i++) 1462 { 1463 basic_block bb = BASIC_BLOCK (i); 1464 1465 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1466 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1467 } 1468 1469 ENTRY_BLOCK_PTR->global_live_at_end 1470 = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1471 EXIT_BLOCK_PTR->global_live_at_start 1472 = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1473 1474 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1475} 1476 1477void 1478allocate_reg_life_data () 1479{ 1480 int i; 1481 1482 max_regno = max_reg_num (); 1483 1484 /* Recalculate the register space, in case it has grown. Old style 1485 vector oriented regsets would set regset_{size,bytes} here also. */ 1486 allocate_reg_info (max_regno, FALSE, FALSE); 1487 1488 /* Reset all the data we'll collect in propagate_block and its 1489 subroutines. */ 1490 for (i = 0; i < max_regno; i++) 1491 { 1492 REG_N_SETS (i) = 0; 1493 REG_N_REFS (i) = 0; 1494 REG_N_DEATHS (i) = 0; 1495 REG_N_CALLS_CROSSED (i) = 0; 1496 REG_LIVE_LENGTH (i) = 0; 1497 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN; 1498 } 1499} 1500 1501/* Delete dead instructions for propagate_block. */ 1502 1503static void 1504propagate_block_delete_insn (bb, insn) 1505 basic_block bb; 1506 rtx insn; 1507{ 1508 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX); 1509 bool purge = false; 1510 1511 /* If the insn referred to a label, and that label was attached to 1512 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's 1513 pretty much mandatory to delete it, because the ADDR_VEC may be 1514 referencing labels that no longer exist. 1515 1516 INSN may reference a deleted label, particularly when a jump 1517 table has been optimized into a direct jump. There's no 1518 real good way to fix up the reference to the deleted label 1519 when the label is deleted, so we just allow it here. 1520 1521 After dead code elimination is complete, we do search for 1522 any REG_LABEL notes which reference deleted labels as a 1523 sanity check. */ 1524 1525 if (inote && GET_CODE (inote) == CODE_LABEL) 1526 { 1527 rtx label = XEXP (inote, 0); 1528 rtx next; 1529 1530 /* The label may be forced if it has been put in the constant 1531 pool. If that is the only use we must discard the table 1532 jump following it, but not the label itself. */ 1533 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label) 1534 && (next = next_nonnote_insn (label)) != NULL 1535 && GET_CODE (next) == JUMP_INSN 1536 && (GET_CODE (PATTERN (next)) == ADDR_VEC 1537 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) 1538 { 1539 rtx pat = PATTERN (next); 1540 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC; 1541 int len = XVECLEN (pat, diff_vec_p); 1542 int i; 1543 1544 for (i = 0; i < len; i++) 1545 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--; 1546 1547 delete_insn (next); 1548 } 1549 } 1550 1551 if (bb->end == insn) 1552 purge = true; 1553 delete_insn (insn); 1554 if (purge) 1555 purge_dead_edges (bb); 1556} 1557 1558/* Delete dead libcalls for propagate_block. Return the insn 1559 before the libcall. */ 1560 1561static rtx 1562propagate_block_delete_libcall ( insn, note) 1563 rtx insn, note; 1564{ 1565 rtx first = XEXP (note, 0); 1566 rtx before = PREV_INSN (first); 1567 1568 delete_insn_chain (first, insn); 1569 return before; 1570} 1571 1572/* Update the life-status of regs for one insn. Return the previous insn. */ 1573 1574rtx 1575propagate_one_insn (pbi, insn) 1576 struct propagate_block_info *pbi; 1577 rtx insn; 1578{ 1579 rtx prev = PREV_INSN (insn); 1580 int flags = pbi->flags; 1581 int insn_is_dead = 0; 1582 int libcall_is_dead = 0; 1583 rtx note; 1584 int i; 1585 1586 if (! INSN_P (insn)) 1587 return prev; 1588 1589 note = find_reg_note (insn, REG_RETVAL, NULL_RTX); 1590 if (flags & PROP_SCAN_DEAD_CODE) 1591 { 1592 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn)); 1593 libcall_is_dead = (insn_is_dead && note != 0 1594 && libcall_dead_p (pbi, note, insn)); 1595 } 1596 1597 /* If an instruction consists of just dead store(s) on final pass, 1598 delete it. */ 1599 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead) 1600 { 1601 /* If we're trying to delete a prologue or epilogue instruction 1602 that isn't flagged as possibly being dead, something is wrong. 1603 But if we are keeping the stack pointer depressed, we might well 1604 be deleting insns that are used to compute the amount to update 1605 it by, so they are fine. */ 1606 if (reload_completed 1607 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE 1608 && (TYPE_RETURNS_STACK_DEPRESSED 1609 (TREE_TYPE (current_function_decl)))) 1610 && (((HAVE_epilogue || HAVE_prologue) 1611 && prologue_epilogue_contains (insn)) 1612 || (HAVE_sibcall_epilogue 1613 && sibcall_epilogue_contains (insn))) 1614 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0) 1615 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn); 1616 1617 /* Record sets. Do this even for dead instructions, since they 1618 would have killed the values if they hadn't been deleted. */ 1619 mark_set_regs (pbi, PATTERN (insn), insn); 1620 1621 /* CC0 is now known to be dead. Either this insn used it, 1622 in which case it doesn't anymore, or clobbered it, 1623 so the next insn can't use it. */ 1624 pbi->cc0_live = 0; 1625 1626 if (libcall_is_dead) 1627 prev = propagate_block_delete_libcall ( insn, note); 1628 else 1629 { 1630 1631 /* If INSN contains a RETVAL note and is dead, but the libcall 1632 as a whole is not dead, then we want to remove INSN, but 1633 not the whole libcall sequence. 1634 1635 However, we need to also remove the dangling REG_LIBCALL 1636 note so that we do not have mis-matched LIBCALL/RETVAL 1637 notes. In theory we could find a new location for the 1638 REG_RETVAL note, but it hardly seems worth the effort. 1639 1640 NOTE at this point will be the RETVAL note if it exists. */ 1641 if (note) 1642 { 1643 rtx libcall_note; 1644 1645 libcall_note 1646 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX); 1647 remove_note (XEXP (note, 0), libcall_note); 1648 } 1649 1650 /* Similarly if INSN contains a LIBCALL note, remove the 1651 dangling REG_RETVAL note. */ 1652 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX); 1653 if (note) 1654 { 1655 rtx retval_note; 1656 1657 retval_note 1658 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX); 1659 remove_note (XEXP (note, 0), retval_note); 1660 } 1661 1662 /* Now delete INSN. */ 1663 propagate_block_delete_insn (pbi->bb, insn); 1664 } 1665 1666 return prev; 1667 } 1668 1669 /* See if this is an increment or decrement that can be merged into 1670 a following memory address. */ 1671#ifdef AUTO_INC_DEC 1672 { 1673 rtx x = single_set (insn); 1674 1675 /* Does this instruction increment or decrement a register? */ 1676 if ((flags & PROP_AUTOINC) 1677 && x != 0 1678 && GET_CODE (SET_DEST (x)) == REG 1679 && (GET_CODE (SET_SRC (x)) == PLUS 1680 || GET_CODE (SET_SRC (x)) == MINUS) 1681 && XEXP (SET_SRC (x), 0) == SET_DEST (x) 1682 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT 1683 /* Ok, look for a following memory ref we can combine with. 1684 If one is found, change the memory ref to a PRE_INC 1685 or PRE_DEC, cancel this insn, and return 1. 1686 Return 0 if nothing has been done. */ 1687 && try_pre_increment_1 (pbi, insn)) 1688 return prev; 1689 } 1690#endif /* AUTO_INC_DEC */ 1691 1692 CLEAR_REG_SET (pbi->new_set); 1693 1694 /* If this is not the final pass, and this insn is copying the value of 1695 a library call and it's dead, don't scan the insns that perform the 1696 library call, so that the call's arguments are not marked live. */ 1697 if (libcall_is_dead) 1698 { 1699 /* Record the death of the dest reg. */ 1700 mark_set_regs (pbi, PATTERN (insn), insn); 1701 1702 insn = XEXP (note, 0); 1703 return PREV_INSN (insn); 1704 } 1705 else if (GET_CODE (PATTERN (insn)) == SET 1706 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx 1707 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS 1708 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx 1709 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT) 1710 /* We have an insn to pop a constant amount off the stack. 1711 (Such insns use PLUS regardless of the direction of the stack, 1712 and any insn to adjust the stack by a constant is always a pop.) 1713 These insns, if not dead stores, have no effect on life. */ 1714 ; 1715 else 1716 { 1717 rtx note; 1718 /* Any regs live at the time of a call instruction must not go 1719 in a register clobbered by calls. Find all regs now live and 1720 record this for them. */ 1721 1722 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO)) 1723 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, 1724 { REG_N_CALLS_CROSSED (i)++; }); 1725 1726 /* Record sets. Do this even for dead instructions, since they 1727 would have killed the values if they hadn't been deleted. */ 1728 mark_set_regs (pbi, PATTERN (insn), insn); 1729 1730 if (GET_CODE (insn) == CALL_INSN) 1731 { 1732 int i; 1733 rtx note, cond; 1734 1735 cond = NULL_RTX; 1736 if (GET_CODE (PATTERN (insn)) == COND_EXEC) 1737 cond = COND_EXEC_TEST (PATTERN (insn)); 1738 1739 /* Non-constant calls clobber memory. */ 1740 if (! CONST_OR_PURE_CALL_P (insn)) 1741 { 1742 free_EXPR_LIST_list (&pbi->mem_set_list); 1743 pbi->mem_set_list_len = 0; 1744 } 1745 1746 /* There may be extra registers to be clobbered. */ 1747 for (note = CALL_INSN_FUNCTION_USAGE (insn); 1748 note; 1749 note = XEXP (note, 1)) 1750 if (GET_CODE (XEXP (note, 0)) == CLOBBER) 1751 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0), 1752 cond, insn, pbi->flags); 1753 1754 /* Calls change all call-used and global registers. */ 1755 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1756 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) 1757 { 1758 /* We do not want REG_UNUSED notes for these registers. */ 1759 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i), 1760 cond, insn, 1761 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO)); 1762 } 1763 } 1764 1765 /* If an insn doesn't use CC0, it becomes dead since we assume 1766 that every insn clobbers it. So show it dead here; 1767 mark_used_regs will set it live if it is referenced. */ 1768 pbi->cc0_live = 0; 1769 1770 /* Record uses. */ 1771 if (! insn_is_dead) 1772 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn); 1773 if ((flags & PROP_EQUAL_NOTES) 1774 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX)) 1775 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)))) 1776 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn); 1777 1778 /* Sometimes we may have inserted something before INSN (such as a move) 1779 when we make an auto-inc. So ensure we will scan those insns. */ 1780#ifdef AUTO_INC_DEC 1781 prev = PREV_INSN (insn); 1782#endif 1783 1784 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN) 1785 { 1786 int i; 1787 rtx note, cond; 1788 1789 cond = NULL_RTX; 1790 if (GET_CODE (PATTERN (insn)) == COND_EXEC) 1791 cond = COND_EXEC_TEST (PATTERN (insn)); 1792 1793 /* Calls use their arguments. */ 1794 for (note = CALL_INSN_FUNCTION_USAGE (insn); 1795 note; 1796 note = XEXP (note, 1)) 1797 if (GET_CODE (XEXP (note, 0)) == USE) 1798 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), 1799 cond, insn); 1800 1801 /* The stack ptr is used (honorarily) by a CALL insn. */ 1802 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM); 1803 1804 /* Calls may also reference any of the global registers, 1805 so they are made live. */ 1806 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1807 if (global_regs[i]) 1808 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i), 1809 cond, insn); 1810 } 1811 } 1812 1813 /* On final pass, update counts of how many insns in which each reg 1814 is live. */ 1815 if (flags & PROP_REG_INFO) 1816 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, 1817 { REG_LIVE_LENGTH (i)++; }); 1818 1819 return prev; 1820} 1821 1822/* Initialize a propagate_block_info struct for public consumption. 1823 Note that the structure itself is opaque to this file, but that 1824 the user can use the regsets provided here. */ 1825 1826struct propagate_block_info * 1827init_propagate_block_info (bb, live, local_set, cond_local_set, flags) 1828 basic_block bb; 1829 regset live, local_set, cond_local_set; 1830 int flags; 1831{ 1832 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi)); 1833 1834 pbi->bb = bb; 1835 pbi->reg_live = live; 1836 pbi->mem_set_list = NULL_RTX; 1837 pbi->mem_set_list_len = 0; 1838 pbi->local_set = local_set; 1839 pbi->cond_local_set = cond_local_set; 1840 pbi->cc0_live = 0; 1841 pbi->flags = flags; 1842 1843 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 1844 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx)); 1845 else 1846 pbi->reg_next_use = NULL; 1847 1848 pbi->new_set = BITMAP_XMALLOC (); 1849 1850#ifdef HAVE_conditional_execution 1851 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL, 1852 free_reg_cond_life_info); 1853 pbi->reg_cond_reg = BITMAP_XMALLOC (); 1854 1855 /* If this block ends in a conditional branch, for each register live 1856 from one side of the branch and not the other, record the register 1857 as conditionally dead. */ 1858 if (GET_CODE (bb->end) == JUMP_INSN 1859 && any_condjump_p (bb->end)) 1860 { 1861 regset_head diff_head; 1862 regset diff = INITIALIZE_REG_SET (diff_head); 1863 basic_block bb_true, bb_false; 1864 rtx cond_true, cond_false, set_src; 1865 int i; 1866 1867 /* Identify the successor blocks. */ 1868 bb_true = bb->succ->dest; 1869 if (bb->succ->succ_next != NULL) 1870 { 1871 bb_false = bb->succ->succ_next->dest; 1872 1873 if (bb->succ->flags & EDGE_FALLTHRU) 1874 { 1875 basic_block t = bb_false; 1876 bb_false = bb_true; 1877 bb_true = t; 1878 } 1879 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU)) 1880 abort (); 1881 } 1882 else 1883 { 1884 /* This can happen with a conditional jump to the next insn. */ 1885 if (JUMP_LABEL (bb->end) != bb_true->head) 1886 abort (); 1887 1888 /* Simplest way to do nothing. */ 1889 bb_false = bb_true; 1890 } 1891 1892 /* Extract the condition from the branch. */ 1893 set_src = SET_SRC (pc_set (bb->end)); 1894 cond_true = XEXP (set_src, 0); 1895 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)), 1896 GET_MODE (cond_true), XEXP (cond_true, 0), 1897 XEXP (cond_true, 1)); 1898 if (GET_CODE (XEXP (set_src, 1)) == PC) 1899 { 1900 rtx t = cond_false; 1901 cond_false = cond_true; 1902 cond_true = t; 1903 } 1904 1905 /* Compute which register lead different lives in the successors. */ 1906 if (bitmap_operation (diff, bb_true->global_live_at_start, 1907 bb_false->global_live_at_start, BITMAP_XOR)) 1908 { 1909 rtx reg = XEXP (cond_true, 0); 1910 1911 if (GET_CODE (reg) == SUBREG) 1912 reg = SUBREG_REG (reg); 1913 1914 if (GET_CODE (reg) != REG) 1915 abort (); 1916 1917 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg)); 1918 1919 /* For each such register, mark it conditionally dead. */ 1920 EXECUTE_IF_SET_IN_REG_SET 1921 (diff, 0, i, 1922 { 1923 struct reg_cond_life_info *rcli; 1924 rtx cond; 1925 1926 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli)); 1927 1928 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i)) 1929 cond = cond_false; 1930 else 1931 cond = cond_true; 1932 rcli->condition = cond; 1933 rcli->stores = const0_rtx; 1934 rcli->orig_condition = cond; 1935 1936 splay_tree_insert (pbi->reg_cond_dead, i, 1937 (splay_tree_value) rcli); 1938 }); 1939 } 1940 1941 FREE_REG_SET (diff); 1942 } 1943#endif 1944 1945 /* If this block has no successors, any stores to the frame that aren't 1946 used later in the block are dead. So make a pass over the block 1947 recording any such that are made and show them dead at the end. We do 1948 a very conservative and simple job here. */ 1949 if (optimize 1950 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE 1951 && (TYPE_RETURNS_STACK_DEPRESSED 1952 (TREE_TYPE (current_function_decl)))) 1953 && (flags & PROP_SCAN_DEAD_CODE) 1954 && (bb->succ == NULL 1955 || (bb->succ->succ_next == NULL 1956 && bb->succ->dest == EXIT_BLOCK_PTR 1957 && ! current_function_calls_eh_return))) 1958 { 1959 rtx insn, set; 1960 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn)) 1961 if (GET_CODE (insn) == INSN 1962 && (set = single_set (insn)) 1963 && GET_CODE (SET_DEST (set)) == MEM) 1964 { 1965 rtx mem = SET_DEST (set); 1966 rtx canon_mem = canon_rtx (mem); 1967 1968 /* This optimization is performed by faking a store to the 1969 memory at the end of the block. This doesn't work for 1970 unchanging memories because multiple stores to unchanging 1971 memory is illegal and alias analysis doesn't consider it. */ 1972 if (RTX_UNCHANGING_P (canon_mem)) 1973 continue; 1974 1975 if (XEXP (canon_mem, 0) == frame_pointer_rtx 1976 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS 1977 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx 1978 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT)) 1979 add_to_mem_set_list (pbi, canon_mem); 1980 } 1981 } 1982 1983 return pbi; 1984} 1985 1986/* Release a propagate_block_info struct. */ 1987 1988void 1989free_propagate_block_info (pbi) 1990 struct propagate_block_info *pbi; 1991{ 1992 free_EXPR_LIST_list (&pbi->mem_set_list); 1993 1994 BITMAP_XFREE (pbi->new_set); 1995 1996#ifdef HAVE_conditional_execution 1997 splay_tree_delete (pbi->reg_cond_dead); 1998 BITMAP_XFREE (pbi->reg_cond_reg); 1999#endif 2000 2001 if (pbi->reg_next_use) 2002 free (pbi->reg_next_use); 2003 2004 free (pbi); 2005} 2006 2007/* Compute the registers live at the beginning of a basic block BB from 2008 those live at the end. 2009 2010 When called, REG_LIVE contains those live at the end. On return, it 2011 contains those live at the beginning. 2012 2013 LOCAL_SET, if non-null, will be set with all registers killed 2014 unconditionally by this basic block. 2015 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers 2016 killed conditionally by this basic block. If there is any unconditional 2017 set of a register, then the corresponding bit will be set in LOCAL_SET 2018 and cleared in COND_LOCAL_SET. 2019 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this 2020 case, the resulting set will be equal to the union of the two sets that 2021 would otherwise be computed. 2022 2023 Return non-zero if an INSN is deleted (i.e. by dead code removal). */ 2024 2025int 2026propagate_block (bb, live, local_set, cond_local_set, flags) 2027 basic_block bb; 2028 regset live; 2029 regset local_set; 2030 regset cond_local_set; 2031 int flags; 2032{ 2033 struct propagate_block_info *pbi; 2034 rtx insn, prev; 2035 int changed; 2036 2037 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags); 2038 2039 if (flags & PROP_REG_INFO) 2040 { 2041 int i; 2042 2043 /* Process the regs live at the end of the block. 2044 Mark them as not local to any one basic block. */ 2045 EXECUTE_IF_SET_IN_REG_SET (live, 0, i, 2046 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; }); 2047 } 2048 2049 /* Scan the block an insn at a time from end to beginning. */ 2050 2051 changed = 0; 2052 for (insn = bb->end;; insn = prev) 2053 { 2054 /* If this is a call to `setjmp' et al, warn if any 2055 non-volatile datum is live. */ 2056 if ((flags & PROP_REG_INFO) 2057 && GET_CODE (insn) == CALL_INSN 2058 && find_reg_note (insn, REG_SETJMP, NULL)) 2059 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live); 2060 2061 prev = propagate_one_insn (pbi, insn); 2062 changed |= NEXT_INSN (prev) != insn; 2063 2064 if (insn == bb->head) 2065 break; 2066 } 2067 2068 free_propagate_block_info (pbi); 2069 2070 return changed; 2071} 2072 2073/* Return 1 if X (the body of an insn, or part of it) is just dead stores 2074 (SET expressions whose destinations are registers dead after the insn). 2075 NEEDED is the regset that says which regs are alive after the insn. 2076 2077 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. 2078 2079 If X is the entire body of an insn, NOTES contains the reg notes 2080 pertaining to the insn. */ 2081 2082static int 2083insn_dead_p (pbi, x, call_ok, notes) 2084 struct propagate_block_info *pbi; 2085 rtx x; 2086 int call_ok; 2087 rtx notes ATTRIBUTE_UNUSED; 2088{ 2089 enum rtx_code code = GET_CODE (x); 2090 2091#ifdef AUTO_INC_DEC 2092 /* As flow is invoked after combine, we must take existing AUTO_INC 2093 expressions into account. */ 2094 for (; notes; notes = XEXP (notes, 1)) 2095 { 2096 if (REG_NOTE_KIND (notes) == REG_INC) 2097 { 2098 int regno = REGNO (XEXP (notes, 0)); 2099 2100 /* Don't delete insns to set global regs. */ 2101 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) 2102 || REGNO_REG_SET_P (pbi->reg_live, regno)) 2103 return 0; 2104 } 2105 } 2106#endif 2107 2108 /* If setting something that's a reg or part of one, 2109 see if that register's altered value will be live. */ 2110 2111 if (code == SET) 2112 { 2113 rtx r = SET_DEST (x); 2114 2115#ifdef HAVE_cc0 2116 if (GET_CODE (r) == CC0) 2117 return ! pbi->cc0_live; 2118#endif 2119 2120 /* A SET that is a subroutine call cannot be dead. */ 2121 if (GET_CODE (SET_SRC (x)) == CALL) 2122 { 2123 if (! call_ok) 2124 return 0; 2125 } 2126 2127 /* Don't eliminate loads from volatile memory or volatile asms. */ 2128 else if (volatile_refs_p (SET_SRC (x))) 2129 return 0; 2130 2131 if (GET_CODE (r) == MEM) 2132 { 2133 rtx temp, canon_r; 2134 2135 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode) 2136 return 0; 2137 2138 canon_r = canon_rtx (r); 2139 2140 /* Walk the set of memory locations we are currently tracking 2141 and see if one is an identical match to this memory location. 2142 If so, this memory write is dead (remember, we're walking 2143 backwards from the end of the block to the start). Since 2144 rtx_equal_p does not check the alias set or flags, we also 2145 must have the potential for them to conflict (anti_dependence). */ 2146 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1)) 2147 if (anti_dependence (r, XEXP (temp, 0))) 2148 { 2149 rtx mem = XEXP (temp, 0); 2150 2151 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0)) 2152 && (GET_MODE_SIZE (GET_MODE (canon_r)) 2153 <= GET_MODE_SIZE (GET_MODE (mem)))) 2154 return 1; 2155 2156#ifdef AUTO_INC_DEC 2157 /* Check if memory reference matches an auto increment. Only 2158 post increment/decrement or modify are valid. */ 2159 if (GET_MODE (mem) == GET_MODE (r) 2160 && (GET_CODE (XEXP (mem, 0)) == POST_DEC 2161 || GET_CODE (XEXP (mem, 0)) == POST_INC 2162 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY) 2163 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r) 2164 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0))) 2165 return 1; 2166#endif 2167 } 2168 } 2169 else 2170 { 2171 while (GET_CODE (r) == SUBREG 2172 || GET_CODE (r) == STRICT_LOW_PART 2173 || GET_CODE (r) == ZERO_EXTRACT) 2174 r = XEXP (r, 0); 2175 2176 if (GET_CODE (r) == REG) 2177 { 2178 int regno = REGNO (r); 2179 2180 /* Obvious. */ 2181 if (REGNO_REG_SET_P (pbi->reg_live, regno)) 2182 return 0; 2183 2184 /* If this is a hard register, verify that subsequent 2185 words are not needed. */ 2186 if (regno < FIRST_PSEUDO_REGISTER) 2187 { 2188 int n = HARD_REGNO_NREGS (regno, GET_MODE (r)); 2189 2190 while (--n > 0) 2191 if (REGNO_REG_SET_P (pbi->reg_live, regno+n)) 2192 return 0; 2193 } 2194 2195 /* Don't delete insns to set global regs. */ 2196 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) 2197 return 0; 2198 2199 /* Make sure insns to set the stack pointer aren't deleted. */ 2200 if (regno == STACK_POINTER_REGNUM) 2201 return 0; 2202 2203 /* ??? These bits might be redundant with the force live bits 2204 in calculate_global_regs_live. We would delete from 2205 sequential sets; whether this actually affects real code 2206 for anything but the stack pointer I don't know. */ 2207 /* Make sure insns to set the frame pointer aren't deleted. */ 2208 if (regno == FRAME_POINTER_REGNUM 2209 && (! reload_completed || frame_pointer_needed)) 2210 return 0; 2211#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 2212 if (regno == HARD_FRAME_POINTER_REGNUM 2213 && (! reload_completed || frame_pointer_needed)) 2214 return 0; 2215#endif 2216 2217#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 2218 /* Make sure insns to set arg pointer are never deleted 2219 (if the arg pointer isn't fixed, there will be a USE 2220 for it, so we can treat it normally). */ 2221 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) 2222 return 0; 2223#endif 2224 2225 /* Otherwise, the set is dead. */ 2226 return 1; 2227 } 2228 } 2229 } 2230 2231 /* If performing several activities, insn is dead if each activity 2232 is individually dead. Also, CLOBBERs and USEs can be ignored; a 2233 CLOBBER or USE that's inside a PARALLEL doesn't make the insn 2234 worth keeping. */ 2235 else if (code == PARALLEL) 2236 { 2237 int i = XVECLEN (x, 0); 2238 2239 for (i--; i >= 0; i--) 2240 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER 2241 && GET_CODE (XVECEXP (x, 0, i)) != USE 2242 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX)) 2243 return 0; 2244 2245 return 1; 2246 } 2247 2248 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That 2249 is not necessarily true for hard registers. */ 2250 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG 2251 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER 2252 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0)))) 2253 return 1; 2254 2255 /* We do not check other CLOBBER or USE here. An insn consisting of just 2256 a CLOBBER or just a USE should not be deleted. */ 2257 return 0; 2258} 2259 2260/* If INSN is the last insn in a libcall, and assuming INSN is dead, 2261 return 1 if the entire library call is dead. 2262 This is true if INSN copies a register (hard or pseudo) 2263 and if the hard return reg of the call insn is dead. 2264 (The caller should have tested the destination of the SET inside 2265 INSN already for death.) 2266 2267 If this insn doesn't just copy a register, then we don't 2268 have an ordinary libcall. In that case, cse could not have 2269 managed to substitute the source for the dest later on, 2270 so we can assume the libcall is dead. 2271 2272 PBI is the block info giving pseudoregs live before this insn. 2273 NOTE is the REG_RETVAL note of the insn. */ 2274 2275static int 2276libcall_dead_p (pbi, note, insn) 2277 struct propagate_block_info *pbi; 2278 rtx note; 2279 rtx insn; 2280{ 2281 rtx x = single_set (insn); 2282 2283 if (x) 2284 { 2285 rtx r = SET_SRC (x); 2286 2287 if (GET_CODE (r) == REG) 2288 { 2289 rtx call = XEXP (note, 0); 2290 rtx call_pat; 2291 int i; 2292 2293 /* Find the call insn. */ 2294 while (call != insn && GET_CODE (call) != CALL_INSN) 2295 call = NEXT_INSN (call); 2296 2297 /* If there is none, do nothing special, 2298 since ordinary death handling can understand these insns. */ 2299 if (call == insn) 2300 return 0; 2301 2302 /* See if the hard reg holding the value is dead. 2303 If this is a PARALLEL, find the call within it. */ 2304 call_pat = PATTERN (call); 2305 if (GET_CODE (call_pat) == PARALLEL) 2306 { 2307 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--) 2308 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET 2309 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL) 2310 break; 2311 2312 /* This may be a library call that is returning a value 2313 via invisible pointer. Do nothing special, since 2314 ordinary death handling can understand these insns. */ 2315 if (i < 0) 2316 return 0; 2317 2318 call_pat = XVECEXP (call_pat, 0, i); 2319 } 2320 2321 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call)); 2322 } 2323 } 2324 return 1; 2325} 2326 2327/* Return 1 if register REGNO was used before it was set, i.e. if it is 2328 live at function entry. Don't count global register variables, variables 2329 in registers that can be used for function arg passing, or variables in 2330 fixed hard registers. */ 2331 2332int 2333regno_uninitialized (regno) 2334 unsigned int regno; 2335{ 2336 if (n_basic_blocks == 0 2337 || (regno < FIRST_PSEUDO_REGISTER 2338 && (global_regs[regno] 2339 || fixed_regs[regno] 2340 || FUNCTION_ARG_REGNO_P (regno)))) 2341 return 0; 2342 2343 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno); 2344} 2345 2346/* 1 if register REGNO was alive at a place where `setjmp' was called 2347 and was set more than once or is an argument. 2348 Such regs may be clobbered by `longjmp'. */ 2349 2350int 2351regno_clobbered_at_setjmp (regno) 2352 int regno; 2353{ 2354 if (n_basic_blocks == 0) 2355 return 0; 2356 2357 return ((REG_N_SETS (regno) > 1 2358 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno)) 2359 && REGNO_REG_SET_P (regs_live_at_setjmp, regno)); 2360} 2361 2362/* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the 2363 maximal list size; look for overlaps in mode and select the largest. */ 2364static void 2365add_to_mem_set_list (pbi, mem) 2366 struct propagate_block_info *pbi; 2367 rtx mem; 2368{ 2369 rtx i; 2370 2371 /* We don't know how large a BLKmode store is, so we must not 2372 take them into consideration. */ 2373 if (GET_MODE (mem) == BLKmode) 2374 return; 2375 2376 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1)) 2377 { 2378 rtx e = XEXP (i, 0); 2379 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0))) 2380 { 2381 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e))) 2382 { 2383#ifdef AUTO_INC_DEC 2384 /* If we must store a copy of the mem, we can just modify 2385 the mode of the stored copy. */ 2386 if (pbi->flags & PROP_AUTOINC) 2387 PUT_MODE (e, GET_MODE (mem)); 2388 else 2389#endif 2390 XEXP (i, 0) = mem; 2391 } 2392 return; 2393 } 2394 } 2395 2396 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN) 2397 { 2398#ifdef AUTO_INC_DEC 2399 /* Store a copy of mem, otherwise the address may be 2400 scrogged by find_auto_inc. */ 2401 if (pbi->flags & PROP_AUTOINC) 2402 mem = shallow_copy_rtx (mem); 2403#endif 2404 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list); 2405 pbi->mem_set_list_len++; 2406 } 2407} 2408 2409/* INSN references memory, possibly using autoincrement addressing modes. 2410 Find any entries on the mem_set_list that need to be invalidated due 2411 to an address change. */ 2412 2413static void 2414invalidate_mems_from_autoinc (pbi, insn) 2415 struct propagate_block_info *pbi; 2416 rtx insn; 2417{ 2418 rtx note = REG_NOTES (insn); 2419 for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) 2420 if (REG_NOTE_KIND (note) == REG_INC) 2421 invalidate_mems_from_set (pbi, XEXP (note, 0)); 2422} 2423 2424/* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */ 2425 2426static void 2427invalidate_mems_from_set (pbi, exp) 2428 struct propagate_block_info *pbi; 2429 rtx exp; 2430{ 2431 rtx temp = pbi->mem_set_list; 2432 rtx prev = NULL_RTX; 2433 rtx next; 2434 2435 while (temp) 2436 { 2437 next = XEXP (temp, 1); 2438 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0))) 2439 { 2440 /* Splice this entry out of the list. */ 2441 if (prev) 2442 XEXP (prev, 1) = next; 2443 else 2444 pbi->mem_set_list = next; 2445 free_EXPR_LIST_node (temp); 2446 pbi->mem_set_list_len--; 2447 } 2448 else 2449 prev = temp; 2450 temp = next; 2451 } 2452} 2453 2454/* Process the registers that are set within X. Their bits are set to 2455 1 in the regset DEAD, because they are dead prior to this insn. 2456 2457 If INSN is nonzero, it is the insn being processed. 2458 2459 FLAGS is the set of operations to perform. */ 2460 2461static void 2462mark_set_regs (pbi, x, insn) 2463 struct propagate_block_info *pbi; 2464 rtx x, insn; 2465{ 2466 rtx cond = NULL_RTX; 2467 rtx link; 2468 enum rtx_code code; 2469 2470 if (insn) 2471 for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) 2472 { 2473 if (REG_NOTE_KIND (link) == REG_INC) 2474 mark_set_1 (pbi, SET, XEXP (link, 0), 2475 (GET_CODE (x) == COND_EXEC 2476 ? COND_EXEC_TEST (x) : NULL_RTX), 2477 insn, pbi->flags); 2478 } 2479 retry: 2480 switch (code = GET_CODE (x)) 2481 { 2482 case SET: 2483 case CLOBBER: 2484 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags); 2485 return; 2486 2487 case COND_EXEC: 2488 cond = COND_EXEC_TEST (x); 2489 x = COND_EXEC_CODE (x); 2490 goto retry; 2491 2492 case PARALLEL: 2493 { 2494 int i; 2495 2496 for (i = XVECLEN (x, 0) - 1; i >= 0; i--) 2497 { 2498 rtx sub = XVECEXP (x, 0, i); 2499 switch (code = GET_CODE (sub)) 2500 { 2501 case COND_EXEC: 2502 if (cond != NULL_RTX) 2503 abort (); 2504 2505 cond = COND_EXEC_TEST (sub); 2506 sub = COND_EXEC_CODE (sub); 2507 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER) 2508 break; 2509 /* Fall through. */ 2510 2511 case SET: 2512 case CLOBBER: 2513 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags); 2514 break; 2515 2516 default: 2517 break; 2518 } 2519 } 2520 break; 2521 } 2522 2523 default: 2524 break; 2525 } 2526} 2527 2528/* Process a single set, which appears in INSN. REG (which may not 2529 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is 2530 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC). 2531 If the set is conditional (because it appear in a COND_EXEC), COND 2532 will be the condition. */ 2533 2534static void 2535mark_set_1 (pbi, code, reg, cond, insn, flags) 2536 struct propagate_block_info *pbi; 2537 enum rtx_code code; 2538 rtx reg, cond, insn; 2539 int flags; 2540{ 2541 int regno_first = -1, regno_last = -1; 2542 unsigned long not_dead = 0; 2543 int i; 2544 2545 /* Modifying just one hardware register of a multi-reg value or just a 2546 byte field of a register does not mean the value from before this insn 2547 is now dead. Of course, if it was dead after it's unused now. */ 2548 2549 switch (GET_CODE (reg)) 2550 { 2551 case PARALLEL: 2552 /* Some targets place small structures in registers for return values of 2553 functions. We have to detect this case specially here to get correct 2554 flow information. */ 2555 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--) 2556 if (XEXP (XVECEXP (reg, 0, i), 0) != 0) 2557 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn, 2558 flags); 2559 return; 2560 2561 case ZERO_EXTRACT: 2562 case SIGN_EXTRACT: 2563 case STRICT_LOW_PART: 2564 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */ 2565 do 2566 reg = XEXP (reg, 0); 2567 while (GET_CODE (reg) == SUBREG 2568 || GET_CODE (reg) == ZERO_EXTRACT 2569 || GET_CODE (reg) == SIGN_EXTRACT 2570 || GET_CODE (reg) == STRICT_LOW_PART); 2571 if (GET_CODE (reg) == MEM) 2572 break; 2573 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg)); 2574 /* Fall through. */ 2575 2576 case REG: 2577 regno_last = regno_first = REGNO (reg); 2578 if (regno_first < FIRST_PSEUDO_REGISTER) 2579 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1; 2580 break; 2581 2582 case SUBREG: 2583 if (GET_CODE (SUBREG_REG (reg)) == REG) 2584 { 2585 enum machine_mode outer_mode = GET_MODE (reg); 2586 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg)); 2587 2588 /* Identify the range of registers affected. This is moderately 2589 tricky for hard registers. See alter_subreg. */ 2590 2591 regno_last = regno_first = REGNO (SUBREG_REG (reg)); 2592 if (regno_first < FIRST_PSEUDO_REGISTER) 2593 { 2594 regno_first += subreg_regno_offset (regno_first, inner_mode, 2595 SUBREG_BYTE (reg), 2596 outer_mode); 2597 regno_last = (regno_first 2598 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1); 2599 2600 /* Since we've just adjusted the register number ranges, make 2601 sure REG matches. Otherwise some_was_live will be clear 2602 when it shouldn't have been, and we'll create incorrect 2603 REG_UNUSED notes. */ 2604 reg = gen_rtx_REG (outer_mode, regno_first); 2605 } 2606 else 2607 { 2608 /* If the number of words in the subreg is less than the number 2609 of words in the full register, we have a well-defined partial 2610 set. Otherwise the high bits are undefined. 2611 2612 This is only really applicable to pseudos, since we just took 2613 care of multi-word hard registers. */ 2614 if (((GET_MODE_SIZE (outer_mode) 2615 + UNITS_PER_WORD - 1) / UNITS_PER_WORD) 2616 < ((GET_MODE_SIZE (inner_mode) 2617 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)) 2618 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, 2619 regno_first); 2620 2621 reg = SUBREG_REG (reg); 2622 } 2623 } 2624 else 2625 reg = SUBREG_REG (reg); 2626 break; 2627 2628 default: 2629 break; 2630 } 2631 2632 /* If this set is a MEM, then it kills any aliased writes. 2633 If this set is a REG, then it kills any MEMs which use the reg. */ 2634 if (optimize && (flags & PROP_SCAN_DEAD_CODE)) 2635 { 2636 if (GET_CODE (reg) == REG) 2637 invalidate_mems_from_set (pbi, reg); 2638 2639 /* If the memory reference had embedded side effects (autoincrement 2640 address modes. Then we may need to kill some entries on the 2641 memory set list. */ 2642 if (insn && GET_CODE (reg) == MEM) 2643 invalidate_mems_from_autoinc (pbi, insn); 2644 2645 if (GET_CODE (reg) == MEM && ! side_effects_p (reg) 2646 /* ??? With more effort we could track conditional memory life. */ 2647 && ! cond 2648 /* There are no REG_INC notes for SP, so we can't assume we'll see 2649 everything that invalidates it. To be safe, don't eliminate any 2650 stores though SP; none of them should be redundant anyway. */ 2651 && ! reg_mentioned_p (stack_pointer_rtx, reg)) 2652 add_to_mem_set_list (pbi, canon_rtx (reg)); 2653 } 2654 2655 if (GET_CODE (reg) == REG 2656 && ! (regno_first == FRAME_POINTER_REGNUM 2657 && (! reload_completed || frame_pointer_needed)) 2658#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 2659 && ! (regno_first == HARD_FRAME_POINTER_REGNUM 2660 && (! reload_completed || frame_pointer_needed)) 2661#endif 2662#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 2663 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first]) 2664#endif 2665 ) 2666 { 2667 int some_was_live = 0, some_was_dead = 0; 2668 2669 for (i = regno_first; i <= regno_last; ++i) 2670 { 2671 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i); 2672 if (pbi->local_set) 2673 { 2674 /* Order of the set operation matters here since both 2675 sets may be the same. */ 2676 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i); 2677 if (cond != NULL_RTX 2678 && ! REGNO_REG_SET_P (pbi->local_set, i)) 2679 SET_REGNO_REG_SET (pbi->cond_local_set, i); 2680 else 2681 SET_REGNO_REG_SET (pbi->local_set, i); 2682 } 2683 if (code != CLOBBER) 2684 SET_REGNO_REG_SET (pbi->new_set, i); 2685 2686 some_was_live |= needed_regno; 2687 some_was_dead |= ! needed_regno; 2688 } 2689 2690#ifdef HAVE_conditional_execution 2691 /* Consider conditional death in deciding that the register needs 2692 a death note. */ 2693 if (some_was_live && ! not_dead 2694 /* The stack pointer is never dead. Well, not strictly true, 2695 but it's very difficult to tell from here. Hopefully 2696 combine_stack_adjustments will fix up the most egregious 2697 errors. */ 2698 && regno_first != STACK_POINTER_REGNUM) 2699 { 2700 for (i = regno_first; i <= regno_last; ++i) 2701 if (! mark_regno_cond_dead (pbi, i, cond)) 2702 not_dead |= ((unsigned long) 1) << (i - regno_first); 2703 } 2704#endif 2705 2706 /* Additional data to record if this is the final pass. */ 2707 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO 2708 | PROP_DEATH_NOTES | PROP_AUTOINC)) 2709 { 2710 rtx y; 2711 int blocknum = pbi->bb->index; 2712 2713 y = NULL_RTX; 2714 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 2715 { 2716 y = pbi->reg_next_use[regno_first]; 2717 2718 /* The next use is no longer next, since a store intervenes. */ 2719 for (i = regno_first; i <= regno_last; ++i) 2720 pbi->reg_next_use[i] = 0; 2721 } 2722 2723 if (flags & PROP_REG_INFO) 2724 { 2725 for (i = regno_first; i <= regno_last; ++i) 2726 { 2727 /* Count (weighted) references, stores, etc. This counts a 2728 register twice if it is modified, but that is correct. */ 2729 REG_N_SETS (i) += 1; 2730 REG_N_REFS (i) += 1; 2731 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb); 2732 2733 /* The insns where a reg is live are normally counted 2734 elsewhere, but we want the count to include the insn 2735 where the reg is set, and the normal counting mechanism 2736 would not count it. */ 2737 REG_LIVE_LENGTH (i) += 1; 2738 } 2739 2740 /* If this is a hard reg, record this function uses the reg. */ 2741 if (regno_first < FIRST_PSEUDO_REGISTER) 2742 { 2743 for (i = regno_first; i <= regno_last; i++) 2744 regs_ever_live[i] = 1; 2745 } 2746 else 2747 { 2748 /* Keep track of which basic blocks each reg appears in. */ 2749 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN) 2750 REG_BASIC_BLOCK (regno_first) = blocknum; 2751 else if (REG_BASIC_BLOCK (regno_first) != blocknum) 2752 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL; 2753 } 2754 } 2755 2756 if (! some_was_dead) 2757 { 2758 if (flags & PROP_LOG_LINKS) 2759 { 2760 /* Make a logical link from the next following insn 2761 that uses this register, back to this insn. 2762 The following insns have already been processed. 2763 2764 We don't build a LOG_LINK for hard registers containing 2765 in ASM_OPERANDs. If these registers get replaced, 2766 we might wind up changing the semantics of the insn, 2767 even if reload can make what appear to be valid 2768 assignments later. */ 2769 if (y && (BLOCK_NUM (y) == blocknum) 2770 && (regno_first >= FIRST_PSEUDO_REGISTER 2771 || asm_noperands (PATTERN (y)) < 0)) 2772 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y)); 2773 } 2774 } 2775 else if (not_dead) 2776 ; 2777 else if (! some_was_live) 2778 { 2779 if (flags & PROP_REG_INFO) 2780 REG_N_DEATHS (regno_first) += 1; 2781 2782 if (flags & PROP_DEATH_NOTES) 2783 { 2784 /* Note that dead stores have already been deleted 2785 when possible. If we get here, we have found a 2786 dead store that cannot be eliminated (because the 2787 same insn does something useful). Indicate this 2788 by marking the reg being set as dying here. */ 2789 REG_NOTES (insn) 2790 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn)); 2791 } 2792 } 2793 else 2794 { 2795 if (flags & PROP_DEATH_NOTES) 2796 { 2797 /* This is a case where we have a multi-word hard register 2798 and some, but not all, of the words of the register are 2799 needed in subsequent insns. Write REG_UNUSED notes 2800 for those parts that were not needed. This case should 2801 be rare. */ 2802 2803 for (i = regno_first; i <= regno_last; ++i) 2804 if (! REGNO_REG_SET_P (pbi->reg_live, i)) 2805 REG_NOTES (insn) 2806 = alloc_EXPR_LIST (REG_UNUSED, 2807 gen_rtx_REG (reg_raw_mode[i], i), 2808 REG_NOTES (insn)); 2809 } 2810 } 2811 } 2812 2813 /* Mark the register as being dead. */ 2814 if (some_was_live 2815 /* The stack pointer is never dead. Well, not strictly true, 2816 but it's very difficult to tell from here. Hopefully 2817 combine_stack_adjustments will fix up the most egregious 2818 errors. */ 2819 && regno_first != STACK_POINTER_REGNUM) 2820 { 2821 for (i = regno_first; i <= regno_last; ++i) 2822 if (!(not_dead & (((unsigned long) 1) << (i - regno_first)))) 2823 CLEAR_REGNO_REG_SET (pbi->reg_live, i); 2824 } 2825 } 2826 else if (GET_CODE (reg) == REG) 2827 { 2828 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 2829 pbi->reg_next_use[regno_first] = 0; 2830 } 2831 2832 /* If this is the last pass and this is a SCRATCH, show it will be dying 2833 here and count it. */ 2834 else if (GET_CODE (reg) == SCRATCH) 2835 { 2836 if (flags & PROP_DEATH_NOTES) 2837 REG_NOTES (insn) 2838 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn)); 2839 } 2840} 2841 2842#ifdef HAVE_conditional_execution 2843/* Mark REGNO conditionally dead. 2844 Return true if the register is now unconditionally dead. */ 2845 2846static int 2847mark_regno_cond_dead (pbi, regno, cond) 2848 struct propagate_block_info *pbi; 2849 int regno; 2850 rtx cond; 2851{ 2852 /* If this is a store to a predicate register, the value of the 2853 predicate is changing, we don't know that the predicate as seen 2854 before is the same as that seen after. Flush all dependent 2855 conditions from reg_cond_dead. This will make all such 2856 conditionally live registers unconditionally live. */ 2857 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno)) 2858 flush_reg_cond_reg (pbi, regno); 2859 2860 /* If this is an unconditional store, remove any conditional 2861 life that may have existed. */ 2862 if (cond == NULL_RTX) 2863 splay_tree_remove (pbi->reg_cond_dead, regno); 2864 else 2865 { 2866 splay_tree_node node; 2867 struct reg_cond_life_info *rcli; 2868 rtx ncond; 2869 2870 /* Otherwise this is a conditional set. Record that fact. 2871 It may have been conditionally used, or there may be a 2872 subsequent set with a complimentary condition. */ 2873 2874 node = splay_tree_lookup (pbi->reg_cond_dead, regno); 2875 if (node == NULL) 2876 { 2877 /* The register was unconditionally live previously. 2878 Record the current condition as the condition under 2879 which it is dead. */ 2880 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli)); 2881 rcli->condition = cond; 2882 rcli->stores = cond; 2883 rcli->orig_condition = const0_rtx; 2884 splay_tree_insert (pbi->reg_cond_dead, regno, 2885 (splay_tree_value) rcli); 2886 2887 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); 2888 2889 /* Not unconditionally dead. */ 2890 return 0; 2891 } 2892 else 2893 { 2894 /* The register was conditionally live previously. 2895 Add the new condition to the old. */ 2896 rcli = (struct reg_cond_life_info *) node->value; 2897 ncond = rcli->condition; 2898 ncond = ior_reg_cond (ncond, cond, 1); 2899 if (rcli->stores == const0_rtx) 2900 rcli->stores = cond; 2901 else if (rcli->stores != const1_rtx) 2902 rcli->stores = ior_reg_cond (rcli->stores, cond, 1); 2903 2904 /* If the register is now unconditionally dead, remove the entry 2905 in the splay_tree. A register is unconditionally dead if the 2906 dead condition ncond is true. A register is also unconditionally 2907 dead if the sum of all conditional stores is an unconditional 2908 store (stores is true), and the dead condition is identically the 2909 same as the original dead condition initialized at the end of 2910 the block. This is a pointer compare, not an rtx_equal_p 2911 compare. */ 2912 if (ncond == const1_rtx 2913 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx)) 2914 splay_tree_remove (pbi->reg_cond_dead, regno); 2915 else 2916 { 2917 rcli->condition = ncond; 2918 2919 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); 2920 2921 /* Not unconditionally dead. */ 2922 return 0; 2923 } 2924 } 2925 } 2926 2927 return 1; 2928} 2929 2930/* Called from splay_tree_delete for pbi->reg_cond_life. */ 2931 2932static void 2933free_reg_cond_life_info (value) 2934 splay_tree_value value; 2935{ 2936 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value; 2937 free (rcli); 2938} 2939 2940/* Helper function for flush_reg_cond_reg. */ 2941 2942static int 2943flush_reg_cond_reg_1 (node, data) 2944 splay_tree_node node; 2945 void *data; 2946{ 2947 struct reg_cond_life_info *rcli; 2948 int *xdata = (int *) data; 2949 unsigned int regno = xdata[0]; 2950 2951 /* Don't need to search if last flushed value was farther on in 2952 the in-order traversal. */ 2953 if (xdata[1] >= (int) node->key) 2954 return 0; 2955 2956 /* Splice out portions of the expression that refer to regno. */ 2957 rcli = (struct reg_cond_life_info *) node->value; 2958 rcli->condition = elim_reg_cond (rcli->condition, regno); 2959 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx) 2960 rcli->stores = elim_reg_cond (rcli->stores, regno); 2961 2962 /* If the entire condition is now false, signal the node to be removed. */ 2963 if (rcli->condition == const0_rtx) 2964 { 2965 xdata[1] = node->key; 2966 return -1; 2967 } 2968 else if (rcli->condition == const1_rtx) 2969 abort (); 2970 2971 return 0; 2972} 2973 2974/* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */ 2975 2976static void 2977flush_reg_cond_reg (pbi, regno) 2978 struct propagate_block_info *pbi; 2979 int regno; 2980{ 2981 int pair[2]; 2982 2983 pair[0] = regno; 2984 pair[1] = -1; 2985 while (splay_tree_foreach (pbi->reg_cond_dead, 2986 flush_reg_cond_reg_1, pair) == -1) 2987 splay_tree_remove (pbi->reg_cond_dead, pair[1]); 2988 2989 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno); 2990} 2991 2992/* Logical arithmetic on predicate conditions. IOR, NOT and AND. 2993 For ior/and, the ADD flag determines whether we want to add the new 2994 condition X to the old one unconditionally. If it is zero, we will 2995 only return a new expression if X allows us to simplify part of 2996 OLD, otherwise we return NULL to the caller. 2997 If ADD is nonzero, we will return a new condition in all cases. The 2998 toplevel caller of one of these functions should always pass 1 for 2999 ADD. */ 3000 3001static rtx 3002ior_reg_cond (old, x, add) 3003 rtx old, x; 3004 int add; 3005{ 3006 rtx op0, op1; 3007 3008 if (GET_RTX_CLASS (GET_CODE (old)) == '<') 3009 { 3010 if (GET_RTX_CLASS (GET_CODE (x)) == '<' 3011 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old)) 3012 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3013 return const1_rtx; 3014 if (GET_CODE (x) == GET_CODE (old) 3015 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3016 return old; 3017 if (! add) 3018 return NULL; 3019 return gen_rtx_IOR (0, old, x); 3020 } 3021 3022 switch (GET_CODE (old)) 3023 { 3024 case IOR: 3025 op0 = ior_reg_cond (XEXP (old, 0), x, 0); 3026 op1 = ior_reg_cond (XEXP (old, 1), x, 0); 3027 if (op0 != NULL || op1 != NULL) 3028 { 3029 if (op0 == const0_rtx) 3030 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x); 3031 if (op1 == const0_rtx) 3032 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x); 3033 if (op0 == const1_rtx || op1 == const1_rtx) 3034 return const1_rtx; 3035 if (op0 == NULL) 3036 op0 = gen_rtx_IOR (0, XEXP (old, 0), x); 3037 else if (rtx_equal_p (x, op0)) 3038 /* (x | A) | x ~ (x | A). */ 3039 return old; 3040 if (op1 == NULL) 3041 op1 = gen_rtx_IOR (0, XEXP (old, 1), x); 3042 else if (rtx_equal_p (x, op1)) 3043 /* (A | x) | x ~ (A | x). */ 3044 return old; 3045 return gen_rtx_IOR (0, op0, op1); 3046 } 3047 if (! add) 3048 return NULL; 3049 return gen_rtx_IOR (0, old, x); 3050 3051 case AND: 3052 op0 = ior_reg_cond (XEXP (old, 0), x, 0); 3053 op1 = ior_reg_cond (XEXP (old, 1), x, 0); 3054 if (op0 != NULL || op1 != NULL) 3055 { 3056 if (op0 == const1_rtx) 3057 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x); 3058 if (op1 == const1_rtx) 3059 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x); 3060 if (op0 == const0_rtx || op1 == const0_rtx) 3061 return const0_rtx; 3062 if (op0 == NULL) 3063 op0 = gen_rtx_IOR (0, XEXP (old, 0), x); 3064 else if (rtx_equal_p (x, op0)) 3065 /* (x & A) | x ~ x. */ 3066 return op0; 3067 if (op1 == NULL) 3068 op1 = gen_rtx_IOR (0, XEXP (old, 1), x); 3069 else if (rtx_equal_p (x, op1)) 3070 /* (A & x) | x ~ x. */ 3071 return op1; 3072 return gen_rtx_AND (0, op0, op1); 3073 } 3074 if (! add) 3075 return NULL; 3076 return gen_rtx_IOR (0, old, x); 3077 3078 case NOT: 3079 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0); 3080 if (op0 != NULL) 3081 return not_reg_cond (op0); 3082 if (! add) 3083 return NULL; 3084 return gen_rtx_IOR (0, old, x); 3085 3086 default: 3087 abort (); 3088 } 3089} 3090 3091static rtx 3092not_reg_cond (x) 3093 rtx x; 3094{ 3095 enum rtx_code x_code; 3096 3097 if (x == const0_rtx) 3098 return const1_rtx; 3099 else if (x == const1_rtx) 3100 return const0_rtx; 3101 x_code = GET_CODE (x); 3102 if (x_code == NOT) 3103 return XEXP (x, 0); 3104 if (GET_RTX_CLASS (x_code) == '<' 3105 && GET_CODE (XEXP (x, 0)) == REG) 3106 { 3107 if (XEXP (x, 1) != const0_rtx) 3108 abort (); 3109 3110 return gen_rtx_fmt_ee (reverse_condition (x_code), 3111 VOIDmode, XEXP (x, 0), const0_rtx); 3112 } 3113 return gen_rtx_NOT (0, x); 3114} 3115 3116static rtx 3117and_reg_cond (old, x, add) 3118 rtx old, x; 3119 int add; 3120{ 3121 rtx op0, op1; 3122 3123 if (GET_RTX_CLASS (GET_CODE (old)) == '<') 3124 { 3125 if (GET_RTX_CLASS (GET_CODE (x)) == '<' 3126 && GET_CODE (x) == reverse_condition (GET_CODE (old)) 3127 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3128 return const0_rtx; 3129 if (GET_CODE (x) == GET_CODE (old) 3130 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3131 return old; 3132 if (! add) 3133 return NULL; 3134 return gen_rtx_AND (0, old, x); 3135 } 3136 3137 switch (GET_CODE (old)) 3138 { 3139 case IOR: 3140 op0 = and_reg_cond (XEXP (old, 0), x, 0); 3141 op1 = and_reg_cond (XEXP (old, 1), x, 0); 3142 if (op0 != NULL || op1 != NULL) 3143 { 3144 if (op0 == const0_rtx) 3145 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x); 3146 if (op1 == const0_rtx) 3147 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x); 3148 if (op0 == const1_rtx || op1 == const1_rtx) 3149 return const1_rtx; 3150 if (op0 == NULL) 3151 op0 = gen_rtx_AND (0, XEXP (old, 0), x); 3152 else if (rtx_equal_p (x, op0)) 3153 /* (x | A) & x ~ x. */ 3154 return op0; 3155 if (op1 == NULL) 3156 op1 = gen_rtx_AND (0, XEXP (old, 1), x); 3157 else if (rtx_equal_p (x, op1)) 3158 /* (A | x) & x ~ x. */ 3159 return op1; 3160 return gen_rtx_IOR (0, op0, op1); 3161 } 3162 if (! add) 3163 return NULL; 3164 return gen_rtx_AND (0, old, x); 3165 3166 case AND: 3167 op0 = and_reg_cond (XEXP (old, 0), x, 0); 3168 op1 = and_reg_cond (XEXP (old, 1), x, 0); 3169 if (op0 != NULL || op1 != NULL) 3170 { 3171 if (op0 == const1_rtx) 3172 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x); 3173 if (op1 == const1_rtx) 3174 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x); 3175 if (op0 == const0_rtx || op1 == const0_rtx) 3176 return const0_rtx; 3177 if (op0 == NULL) 3178 op0 = gen_rtx_AND (0, XEXP (old, 0), x); 3179 else if (rtx_equal_p (x, op0)) 3180 /* (x & A) & x ~ (x & A). */ 3181 return old; 3182 if (op1 == NULL) 3183 op1 = gen_rtx_AND (0, XEXP (old, 1), x); 3184 else if (rtx_equal_p (x, op1)) 3185 /* (A & x) & x ~ (A & x). */ 3186 return old; 3187 return gen_rtx_AND (0, op0, op1); 3188 } 3189 if (! add) 3190 return NULL; 3191 return gen_rtx_AND (0, old, x); 3192 3193 case NOT: 3194 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0); 3195 if (op0 != NULL) 3196 return not_reg_cond (op0); 3197 if (! add) 3198 return NULL; 3199 return gen_rtx_AND (0, old, x); 3200 3201 default: 3202 abort (); 3203 } 3204} 3205 3206/* Given a condition X, remove references to reg REGNO and return the 3207 new condition. The removal will be done so that all conditions 3208 involving REGNO are considered to evaluate to false. This function 3209 is used when the value of REGNO changes. */ 3210 3211static rtx 3212elim_reg_cond (x, regno) 3213 rtx x; 3214 unsigned int regno; 3215{ 3216 rtx op0, op1; 3217 3218 if (GET_RTX_CLASS (GET_CODE (x)) == '<') 3219 { 3220 if (REGNO (XEXP (x, 0)) == regno) 3221 return const0_rtx; 3222 return x; 3223 } 3224 3225 switch (GET_CODE (x)) 3226 { 3227 case AND: 3228 op0 = elim_reg_cond (XEXP (x, 0), regno); 3229 op1 = elim_reg_cond (XEXP (x, 1), regno); 3230 if (op0 == const0_rtx || op1 == const0_rtx) 3231 return const0_rtx; 3232 if (op0 == const1_rtx) 3233 return op1; 3234 if (op1 == const1_rtx) 3235 return op0; 3236 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1)) 3237 return x; 3238 return gen_rtx_AND (0, op0, op1); 3239 3240 case IOR: 3241 op0 = elim_reg_cond (XEXP (x, 0), regno); 3242 op1 = elim_reg_cond (XEXP (x, 1), regno); 3243 if (op0 == const1_rtx || op1 == const1_rtx) 3244 return const1_rtx; 3245 if (op0 == const0_rtx) 3246 return op1; 3247 if (op1 == const0_rtx) 3248 return op0; 3249 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1)) 3250 return x; 3251 return gen_rtx_IOR (0, op0, op1); 3252 3253 case NOT: 3254 op0 = elim_reg_cond (XEXP (x, 0), regno); 3255 if (op0 == const0_rtx) 3256 return const1_rtx; 3257 if (op0 == const1_rtx) 3258 return const0_rtx; 3259 if (op0 != XEXP (x, 0)) 3260 return not_reg_cond (op0); 3261 return x; 3262 3263 default: 3264 abort (); 3265 } 3266} 3267#endif /* HAVE_conditional_execution */ 3268 3269#ifdef AUTO_INC_DEC 3270 3271/* Try to substitute the auto-inc expression INC as the address inside 3272 MEM which occurs in INSN. Currently, the address of MEM is an expression 3273 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn 3274 that has a single set whose source is a PLUS of INCR_REG and something 3275 else. */ 3276 3277static void 3278attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg) 3279 struct propagate_block_info *pbi; 3280 rtx inc, insn, mem, incr, incr_reg; 3281{ 3282 int regno = REGNO (incr_reg); 3283 rtx set = single_set (incr); 3284 rtx q = SET_DEST (set); 3285 rtx y = SET_SRC (set); 3286 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1; 3287 3288 /* Make sure this reg appears only once in this insn. */ 3289 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1) 3290 return; 3291 3292 if (dead_or_set_p (incr, incr_reg) 3293 /* Mustn't autoinc an eliminable register. */ 3294 && (regno >= FIRST_PSEUDO_REGISTER 3295 || ! TEST_HARD_REG_BIT (elim_reg_set, regno))) 3296 { 3297 /* This is the simple case. Try to make the auto-inc. If 3298 we can't, we are done. Otherwise, we will do any 3299 needed updates below. */ 3300 if (! validate_change (insn, &XEXP (mem, 0), inc, 0)) 3301 return; 3302 } 3303 else if (GET_CODE (q) == REG 3304 /* PREV_INSN used here to check the semi-open interval 3305 [insn,incr). */ 3306 && ! reg_used_between_p (q, PREV_INSN (insn), incr) 3307 /* We must also check for sets of q as q may be 3308 a call clobbered hard register and there may 3309 be a call between PREV_INSN (insn) and incr. */ 3310 && ! reg_set_between_p (q, PREV_INSN (insn), incr)) 3311 { 3312 /* We have *p followed sometime later by q = p+size. 3313 Both p and q must be live afterward, 3314 and q is not used between INSN and its assignment. 3315 Change it to q = p, ...*q..., q = q+size. 3316 Then fall into the usual case. */ 3317 rtx insns, temp; 3318 3319 start_sequence (); 3320 emit_move_insn (q, incr_reg); 3321 insns = get_insns (); 3322 end_sequence (); 3323 3324 /* If we can't make the auto-inc, or can't make the 3325 replacement into Y, exit. There's no point in making 3326 the change below if we can't do the auto-inc and doing 3327 so is not correct in the pre-inc case. */ 3328 3329 XEXP (inc, 0) = q; 3330 validate_change (insn, &XEXP (mem, 0), inc, 1); 3331 validate_change (incr, &XEXP (y, opnum), q, 1); 3332 if (! apply_change_group ()) 3333 return; 3334 3335 /* We now know we'll be doing this change, so emit the 3336 new insn(s) and do the updates. */ 3337 emit_insns_before (insns, insn); 3338 3339 if (pbi->bb->head == insn) 3340 pbi->bb->head = insns; 3341 3342 /* INCR will become a NOTE and INSN won't contain a 3343 use of INCR_REG. If a use of INCR_REG was just placed in 3344 the insn before INSN, make that the next use. 3345 Otherwise, invalidate it. */ 3346 if (GET_CODE (PREV_INSN (insn)) == INSN 3347 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET 3348 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg) 3349 pbi->reg_next_use[regno] = PREV_INSN (insn); 3350 else 3351 pbi->reg_next_use[regno] = 0; 3352 3353 incr_reg = q; 3354 regno = REGNO (q); 3355 3356 /* REGNO is now used in INCR which is below INSN, but 3357 it previously wasn't live here. If we don't mark 3358 it as live, we'll put a REG_DEAD note for it 3359 on this insn, which is incorrect. */ 3360 SET_REGNO_REG_SET (pbi->reg_live, regno); 3361 3362 /* If there are any calls between INSN and INCR, show 3363 that REGNO now crosses them. */ 3364 for (temp = insn; temp != incr; temp = NEXT_INSN (temp)) 3365 if (GET_CODE (temp) == CALL_INSN) 3366 REG_N_CALLS_CROSSED (regno)++; 3367 3368 /* Invalidate alias info for Q since we just changed its value. */ 3369 clear_reg_alias_info (q); 3370 } 3371 else 3372 return; 3373 3374 /* If we haven't returned, it means we were able to make the 3375 auto-inc, so update the status. First, record that this insn 3376 has an implicit side effect. */ 3377 3378 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn)); 3379 3380 /* Modify the old increment-insn to simply copy 3381 the already-incremented value of our register. */ 3382 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0)) 3383 abort (); 3384 3385 /* If that makes it a no-op (copying the register into itself) delete 3386 it so it won't appear to be a "use" and a "set" of this 3387 register. */ 3388 if (REGNO (SET_DEST (set)) == REGNO (incr_reg)) 3389 { 3390 /* If the original source was dead, it's dead now. */ 3391 rtx note; 3392 3393 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX) 3394 { 3395 remove_note (incr, note); 3396 if (XEXP (note, 0) != incr_reg) 3397 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0))); 3398 } 3399 3400 PUT_CODE (incr, NOTE); 3401 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED; 3402 NOTE_SOURCE_FILE (incr) = 0; 3403 } 3404 3405 if (regno >= FIRST_PSEUDO_REGISTER) 3406 { 3407 /* Count an extra reference to the reg. When a reg is 3408 incremented, spilling it is worse, so we want to make 3409 that less likely. */ 3410 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb); 3411 3412 /* Count the increment as a setting of the register, 3413 even though it isn't a SET in rtl. */ 3414 REG_N_SETS (regno)++; 3415 } 3416} 3417 3418/* X is a MEM found in INSN. See if we can convert it into an auto-increment 3419 reference. */ 3420 3421static void 3422find_auto_inc (pbi, x, insn) 3423 struct propagate_block_info *pbi; 3424 rtx x; 3425 rtx insn; 3426{ 3427 rtx addr = XEXP (x, 0); 3428 HOST_WIDE_INT offset = 0; 3429 rtx set, y, incr, inc_val; 3430 int regno; 3431 int size = GET_MODE_SIZE (GET_MODE (x)); 3432 3433 if (GET_CODE (insn) == JUMP_INSN) 3434 return; 3435 3436 /* Here we detect use of an index register which might be good for 3437 postincrement, postdecrement, preincrement, or predecrement. */ 3438 3439 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT) 3440 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0); 3441 3442 if (GET_CODE (addr) != REG) 3443 return; 3444 3445 regno = REGNO (addr); 3446 3447 /* Is the next use an increment that might make auto-increment? */ 3448 incr = pbi->reg_next_use[regno]; 3449 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn)) 3450 return; 3451 set = single_set (incr); 3452 if (set == 0 || GET_CODE (set) != SET) 3453 return; 3454 y = SET_SRC (set); 3455 3456 if (GET_CODE (y) != PLUS) 3457 return; 3458 3459 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr)) 3460 inc_val = XEXP (y, 1); 3461 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr)) 3462 inc_val = XEXP (y, 0); 3463 else 3464 return; 3465 3466 if (GET_CODE (inc_val) == CONST_INT) 3467 { 3468 if (HAVE_POST_INCREMENT 3469 && (INTVAL (inc_val) == size && offset == 0)) 3470 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x, 3471 incr, addr); 3472 else if (HAVE_POST_DECREMENT 3473 && (INTVAL (inc_val) == -size && offset == 0)) 3474 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x, 3475 incr, addr); 3476 else if (HAVE_PRE_INCREMENT 3477 && (INTVAL (inc_val) == size && offset == size)) 3478 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x, 3479 incr, addr); 3480 else if (HAVE_PRE_DECREMENT 3481 && (INTVAL (inc_val) == -size && offset == -size)) 3482 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x, 3483 incr, addr); 3484 else if (HAVE_POST_MODIFY_DISP && offset == 0) 3485 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr, 3486 gen_rtx_PLUS (Pmode, 3487 addr, 3488 inc_val)), 3489 insn, x, incr, addr); 3490 } 3491 else if (GET_CODE (inc_val) == REG 3492 && ! reg_set_between_p (inc_val, PREV_INSN (insn), 3493 NEXT_INSN (incr))) 3494 3495 { 3496 if (HAVE_POST_MODIFY_REG && offset == 0) 3497 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr, 3498 gen_rtx_PLUS (Pmode, 3499 addr, 3500 inc_val)), 3501 insn, x, incr, addr); 3502 } 3503} 3504 3505#endif /* AUTO_INC_DEC */ 3506 3507static void 3508mark_used_reg (pbi, reg, cond, insn) 3509 struct propagate_block_info *pbi; 3510 rtx reg; 3511 rtx cond ATTRIBUTE_UNUSED; 3512 rtx insn; 3513{ 3514 unsigned int regno_first, regno_last, i; 3515 int some_was_live, some_was_dead, some_not_set; 3516 3517 regno_last = regno_first = REGNO (reg); 3518 if (regno_first < FIRST_PSEUDO_REGISTER) 3519 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1; 3520 3521 /* Find out if any of this register is live after this instruction. */ 3522 some_was_live = some_was_dead = 0; 3523 for (i = regno_first; i <= regno_last; ++i) 3524 { 3525 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i); 3526 some_was_live |= needed_regno; 3527 some_was_dead |= ! needed_regno; 3528 } 3529 3530 /* Find out if any of the register was set this insn. */ 3531 some_not_set = 0; 3532 for (i = regno_first; i <= regno_last; ++i) 3533 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i); 3534 3535 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 3536 { 3537 /* Record where each reg is used, so when the reg is set we know 3538 the next insn that uses it. */ 3539 pbi->reg_next_use[regno_first] = insn; 3540 } 3541 3542 if (pbi->flags & PROP_REG_INFO) 3543 { 3544 if (regno_first < FIRST_PSEUDO_REGISTER) 3545 { 3546 /* If this is a register we are going to try to eliminate, 3547 don't mark it live here. If we are successful in 3548 eliminating it, it need not be live unless it is used for 3549 pseudos, in which case it will have been set live when it 3550 was allocated to the pseudos. If the register will not 3551 be eliminated, reload will set it live at that point. 3552 3553 Otherwise, record that this function uses this register. */ 3554 /* ??? The PPC backend tries to "eliminate" on the pic 3555 register to itself. This should be fixed. In the mean 3556 time, hack around it. */ 3557 3558 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first) 3559 && (regno_first == FRAME_POINTER_REGNUM 3560 || regno_first == ARG_POINTER_REGNUM))) 3561 for (i = regno_first; i <= regno_last; ++i) 3562 regs_ever_live[i] = 1; 3563 } 3564 else 3565 { 3566 /* Keep track of which basic block each reg appears in. */ 3567 3568 int blocknum = pbi->bb->index; 3569 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN) 3570 REG_BASIC_BLOCK (regno_first) = blocknum; 3571 else if (REG_BASIC_BLOCK (regno_first) != blocknum) 3572 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL; 3573 3574 /* Count (weighted) number of uses of each reg. */ 3575 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb); 3576 REG_N_REFS (regno_first)++; 3577 } 3578 } 3579 3580 /* Record and count the insns in which a reg dies. If it is used in 3581 this insn and was dead below the insn then it dies in this insn. 3582 If it was set in this insn, we do not make a REG_DEAD note; 3583 likewise if we already made such a note. */ 3584 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO)) 3585 && some_was_dead 3586 && some_not_set) 3587 { 3588 /* Check for the case where the register dying partially 3589 overlaps the register set by this insn. */ 3590 if (regno_first != regno_last) 3591 for (i = regno_first; i <= regno_last; ++i) 3592 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i); 3593 3594 /* If none of the words in X is needed, make a REG_DEAD note. 3595 Otherwise, we must make partial REG_DEAD notes. */ 3596 if (! some_was_live) 3597 { 3598 if ((pbi->flags & PROP_DEATH_NOTES) 3599 && ! find_regno_note (insn, REG_DEAD, regno_first)) 3600 REG_NOTES (insn) 3601 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn)); 3602 3603 if (pbi->flags & PROP_REG_INFO) 3604 REG_N_DEATHS (regno_first)++; 3605 } 3606 else 3607 { 3608 /* Don't make a REG_DEAD note for a part of a register 3609 that is set in the insn. */ 3610 for (i = regno_first; i <= regno_last; ++i) 3611 if (! REGNO_REG_SET_P (pbi->reg_live, i) 3612 && ! dead_or_set_regno_p (insn, i)) 3613 REG_NOTES (insn) 3614 = alloc_EXPR_LIST (REG_DEAD, 3615 gen_rtx_REG (reg_raw_mode[i], i), 3616 REG_NOTES (insn)); 3617 } 3618 } 3619 3620 /* Mark the register as being live. */ 3621 for (i = regno_first; i <= regno_last; ++i) 3622 { 3623#ifdef HAVE_conditional_execution 3624 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i); 3625#endif 3626 3627 SET_REGNO_REG_SET (pbi->reg_live, i); 3628 3629#ifdef HAVE_conditional_execution 3630 /* If this is a conditional use, record that fact. If it is later 3631 conditionally set, we'll know to kill the register. */ 3632 if (cond != NULL_RTX) 3633 { 3634 splay_tree_node node; 3635 struct reg_cond_life_info *rcli; 3636 rtx ncond; 3637 3638 if (this_was_live) 3639 { 3640 node = splay_tree_lookup (pbi->reg_cond_dead, i); 3641 if (node == NULL) 3642 { 3643 /* The register was unconditionally live previously. 3644 No need to do anything. */ 3645 } 3646 else 3647 { 3648 /* The register was conditionally live previously. 3649 Subtract the new life cond from the old death cond. */ 3650 rcli = (struct reg_cond_life_info *) node->value; 3651 ncond = rcli->condition; 3652 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1); 3653 3654 /* If the register is now unconditionally live, 3655 remove the entry in the splay_tree. */ 3656 if (ncond == const0_rtx) 3657 splay_tree_remove (pbi->reg_cond_dead, i); 3658 else 3659 { 3660 rcli->condition = ncond; 3661 SET_REGNO_REG_SET (pbi->reg_cond_reg, 3662 REGNO (XEXP (cond, 0))); 3663 } 3664 } 3665 } 3666 else 3667 { 3668 /* The register was not previously live at all. Record 3669 the condition under which it is still dead. */ 3670 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli)); 3671 rcli->condition = not_reg_cond (cond); 3672 rcli->stores = const0_rtx; 3673 rcli->orig_condition = const0_rtx; 3674 splay_tree_insert (pbi->reg_cond_dead, i, 3675 (splay_tree_value) rcli); 3676 3677 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); 3678 } 3679 } 3680 else if (this_was_live) 3681 { 3682 /* The register may have been conditionally live previously, but 3683 is now unconditionally live. Remove it from the conditionally 3684 dead list, so that a conditional set won't cause us to think 3685 it dead. */ 3686 splay_tree_remove (pbi->reg_cond_dead, i); 3687 } 3688#endif 3689 } 3690} 3691 3692/* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses. 3693 This is done assuming the registers needed from X are those that 3694 have 1-bits in PBI->REG_LIVE. 3695 3696 INSN is the containing instruction. If INSN is dead, this function 3697 is not called. */ 3698 3699static void 3700mark_used_regs (pbi, x, cond, insn) 3701 struct propagate_block_info *pbi; 3702 rtx x, cond, insn; 3703{ 3704 RTX_CODE code; 3705 int regno; 3706 int flags = pbi->flags; 3707 3708 retry: 3709 if (!x) 3710 return; 3711 code = GET_CODE (x); 3712 switch (code) 3713 { 3714 case LABEL_REF: 3715 case SYMBOL_REF: 3716 case CONST_INT: 3717 case CONST: 3718 case CONST_DOUBLE: 3719 case CONST_VECTOR: 3720 case PC: 3721 case ADDR_VEC: 3722 case ADDR_DIFF_VEC: 3723 return; 3724 3725#ifdef HAVE_cc0 3726 case CC0: 3727 pbi->cc0_live = 1; 3728 return; 3729#endif 3730 3731 case CLOBBER: 3732 /* If we are clobbering a MEM, mark any registers inside the address 3733 as being used. */ 3734 if (GET_CODE (XEXP (x, 0)) == MEM) 3735 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn); 3736 return; 3737 3738 case MEM: 3739 /* Don't bother watching stores to mems if this is not the 3740 final pass. We'll not be deleting dead stores this round. */ 3741 if (optimize && (flags & PROP_SCAN_DEAD_CODE)) 3742 { 3743 /* Invalidate the data for the last MEM stored, but only if MEM is 3744 something that can be stored into. */ 3745 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF 3746 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0))) 3747 /* Needn't clear the memory set list. */ 3748 ; 3749 else 3750 { 3751 rtx temp = pbi->mem_set_list; 3752 rtx prev = NULL_RTX; 3753 rtx next; 3754 3755 while (temp) 3756 { 3757 next = XEXP (temp, 1); 3758 if (anti_dependence (XEXP (temp, 0), x)) 3759 { 3760 /* Splice temp out of the list. */ 3761 if (prev) 3762 XEXP (prev, 1) = next; 3763 else 3764 pbi->mem_set_list = next; 3765 free_EXPR_LIST_node (temp); 3766 pbi->mem_set_list_len--; 3767 } 3768 else 3769 prev = temp; 3770 temp = next; 3771 } 3772 } 3773 3774 /* If the memory reference had embedded side effects (autoincrement 3775 address modes. Then we may need to kill some entries on the 3776 memory set list. */ 3777 if (insn) 3778 invalidate_mems_from_autoinc (pbi, insn); 3779 } 3780 3781#ifdef AUTO_INC_DEC 3782 if (flags & PROP_AUTOINC) 3783 find_auto_inc (pbi, x, insn); 3784#endif 3785 break; 3786 3787 case SUBREG: 3788#ifdef CLASS_CANNOT_CHANGE_MODE 3789 if (GET_CODE (SUBREG_REG (x)) == REG 3790 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER 3791 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x), 3792 GET_MODE (SUBREG_REG (x)))) 3793 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1; 3794#endif 3795 3796 /* While we're here, optimize this case. */ 3797 x = SUBREG_REG (x); 3798 if (GET_CODE (x) != REG) 3799 goto retry; 3800 /* Fall through. */ 3801 3802 case REG: 3803 /* See a register other than being set => mark it as needed. */ 3804 mark_used_reg (pbi, x, cond, insn); 3805 return; 3806 3807 case SET: 3808 { 3809 rtx testreg = SET_DEST (x); 3810 int mark_dest = 0; 3811 3812 /* If storing into MEM, don't show it as being used. But do 3813 show the address as being used. */ 3814 if (GET_CODE (testreg) == MEM) 3815 { 3816#ifdef AUTO_INC_DEC 3817 if (flags & PROP_AUTOINC) 3818 find_auto_inc (pbi, testreg, insn); 3819#endif 3820 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn); 3821 mark_used_regs (pbi, SET_SRC (x), cond, insn); 3822 return; 3823 } 3824 3825 /* Storing in STRICT_LOW_PART is like storing in a reg 3826 in that this SET might be dead, so ignore it in TESTREG. 3827 but in some other ways it is like using the reg. 3828 3829 Storing in a SUBREG or a bit field is like storing the entire 3830 register in that if the register's value is not used 3831 then this SET is not needed. */ 3832 while (GET_CODE (testreg) == STRICT_LOW_PART 3833 || GET_CODE (testreg) == ZERO_EXTRACT 3834 || GET_CODE (testreg) == SIGN_EXTRACT 3835 || GET_CODE (testreg) == SUBREG) 3836 { 3837#ifdef CLASS_CANNOT_CHANGE_MODE 3838 if (GET_CODE (testreg) == SUBREG 3839 && GET_CODE (SUBREG_REG (testreg)) == REG 3840 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER 3841 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)), 3842 GET_MODE (testreg))) 3843 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1; 3844#endif 3845 3846 /* Modifying a single register in an alternate mode 3847 does not use any of the old value. But these other 3848 ways of storing in a register do use the old value. */ 3849 if (GET_CODE (testreg) == SUBREG 3850 && !((REG_BYTES (SUBREG_REG (testreg)) 3851 + UNITS_PER_WORD - 1) / UNITS_PER_WORD 3852 > (REG_BYTES (testreg) 3853 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)) 3854 ; 3855 else 3856 mark_dest = 1; 3857 3858 testreg = XEXP (testreg, 0); 3859 } 3860 3861 /* If this is a store into a register or group of registers, 3862 recursively scan the value being stored. */ 3863 3864 if ((GET_CODE (testreg) == PARALLEL 3865 && GET_MODE (testreg) == BLKmode) 3866 || (GET_CODE (testreg) == REG 3867 && (regno = REGNO (testreg), 3868 ! (regno == FRAME_POINTER_REGNUM 3869 && (! reload_completed || frame_pointer_needed))) 3870#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 3871 && ! (regno == HARD_FRAME_POINTER_REGNUM 3872 && (! reload_completed || frame_pointer_needed)) 3873#endif 3874#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 3875 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) 3876#endif 3877 )) 3878 { 3879 if (mark_dest) 3880 mark_used_regs (pbi, SET_DEST (x), cond, insn); 3881 mark_used_regs (pbi, SET_SRC (x), cond, insn); 3882 return; 3883 } 3884 } 3885 break; 3886 3887 case ASM_OPERANDS: 3888 case UNSPEC_VOLATILE: 3889 case TRAP_IF: 3890 case ASM_INPUT: 3891 { 3892 /* Traditional and volatile asm instructions must be considered to use 3893 and clobber all hard registers, all pseudo-registers and all of 3894 memory. So must TRAP_IF and UNSPEC_VOLATILE operations. 3895 3896 Consider for instance a volatile asm that changes the fpu rounding 3897 mode. An insn should not be moved across this even if it only uses 3898 pseudo-regs because it might give an incorrectly rounded result. 3899 3900 ?!? Unfortunately, marking all hard registers as live causes massive 3901 problems for the register allocator and marking all pseudos as live 3902 creates mountains of uninitialized variable warnings. 3903 3904 So for now, just clear the memory set list and mark any regs 3905 we can find in ASM_OPERANDS as used. */ 3906 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x)) 3907 { 3908 free_EXPR_LIST_list (&pbi->mem_set_list); 3909 pbi->mem_set_list_len = 0; 3910 } 3911 3912 /* For all ASM_OPERANDS, we must traverse the vector of input operands. 3913 We can not just fall through here since then we would be confused 3914 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate 3915 traditional asms unlike their normal usage. */ 3916 if (code == ASM_OPERANDS) 3917 { 3918 int j; 3919 3920 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++) 3921 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn); 3922 } 3923 break; 3924 } 3925 3926 case COND_EXEC: 3927 if (cond != NULL_RTX) 3928 abort (); 3929 3930 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn); 3931 3932 cond = COND_EXEC_TEST (x); 3933 x = COND_EXEC_CODE (x); 3934 goto retry; 3935 3936 case PHI: 3937 /* We _do_not_ want to scan operands of phi nodes. Operands of 3938 a phi function are evaluated only when control reaches this 3939 block along a particular edge. Therefore, regs that appear 3940 as arguments to phi should not be added to the global live at 3941 start. */ 3942 return; 3943 3944 default: 3945 break; 3946 } 3947 3948 /* Recursively scan the operands of this expression. */ 3949 3950 { 3951 const char * const fmt = GET_RTX_FORMAT (code); 3952 int i; 3953 3954 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 3955 { 3956 if (fmt[i] == 'e') 3957 { 3958 /* Tail recursive case: save a function call level. */ 3959 if (i == 0) 3960 { 3961 x = XEXP (x, 0); 3962 goto retry; 3963 } 3964 mark_used_regs (pbi, XEXP (x, i), cond, insn); 3965 } 3966 else if (fmt[i] == 'E') 3967 { 3968 int j; 3969 for (j = 0; j < XVECLEN (x, i); j++) 3970 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn); 3971 } 3972 } 3973 } 3974} 3975 3976#ifdef AUTO_INC_DEC 3977 3978static int 3979try_pre_increment_1 (pbi, insn) 3980 struct propagate_block_info *pbi; 3981 rtx insn; 3982{ 3983 /* Find the next use of this reg. If in same basic block, 3984 make it do pre-increment or pre-decrement if appropriate. */ 3985 rtx x = single_set (insn); 3986 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1) 3987 * INTVAL (XEXP (SET_SRC (x), 1))); 3988 int regno = REGNO (SET_DEST (x)); 3989 rtx y = pbi->reg_next_use[regno]; 3990 if (y != 0 3991 && SET_DEST (x) != stack_pointer_rtx 3992 && BLOCK_NUM (y) == BLOCK_NUM (insn) 3993 /* Don't do this if the reg dies, or gets set in y; a standard addressing 3994 mode would be better. */ 3995 && ! dead_or_set_p (y, SET_DEST (x)) 3996 && try_pre_increment (y, SET_DEST (x), amount)) 3997 { 3998 /* We have found a suitable auto-increment and already changed 3999 insn Y to do it. So flush this increment instruction. */ 4000 propagate_block_delete_insn (pbi->bb, insn); 4001 4002 /* Count a reference to this reg for the increment insn we are 4003 deleting. When a reg is incremented, spilling it is worse, 4004 so we want to make that less likely. */ 4005 if (regno >= FIRST_PSEUDO_REGISTER) 4006 { 4007 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb); 4008 REG_N_SETS (regno)++; 4009 } 4010 4011 /* Flush any remembered memories depending on the value of 4012 the incremented register. */ 4013 invalidate_mems_from_set (pbi, SET_DEST (x)); 4014 4015 return 1; 4016 } 4017 return 0; 4018} 4019 4020/* Try to change INSN so that it does pre-increment or pre-decrement 4021 addressing on register REG in order to add AMOUNT to REG. 4022 AMOUNT is negative for pre-decrement. 4023 Returns 1 if the change could be made. 4024 This checks all about the validity of the result of modifying INSN. */ 4025 4026static int 4027try_pre_increment (insn, reg, amount) 4028 rtx insn, reg; 4029 HOST_WIDE_INT amount; 4030{ 4031 rtx use; 4032 4033 /* Nonzero if we can try to make a pre-increment or pre-decrement. 4034 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */ 4035 int pre_ok = 0; 4036 /* Nonzero if we can try to make a post-increment or post-decrement. 4037 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,... 4038 It is possible for both PRE_OK and POST_OK to be nonzero if the machine 4039 supports both pre-inc and post-inc, or both pre-dec and post-dec. */ 4040 int post_ok = 0; 4041 4042 /* Nonzero if the opportunity actually requires post-inc or post-dec. */ 4043 int do_post = 0; 4044 4045 /* From the sign of increment, see which possibilities are conceivable 4046 on this target machine. */ 4047 if (HAVE_PRE_INCREMENT && amount > 0) 4048 pre_ok = 1; 4049 if (HAVE_POST_INCREMENT && amount > 0) 4050 post_ok = 1; 4051 4052 if (HAVE_PRE_DECREMENT && amount < 0) 4053 pre_ok = 1; 4054 if (HAVE_POST_DECREMENT && amount < 0) 4055 post_ok = 1; 4056 4057 if (! (pre_ok || post_ok)) 4058 return 0; 4059 4060 /* It is not safe to add a side effect to a jump insn 4061 because if the incremented register is spilled and must be reloaded 4062 there would be no way to store the incremented value back in memory. */ 4063 4064 if (GET_CODE (insn) == JUMP_INSN) 4065 return 0; 4066 4067 use = 0; 4068 if (pre_ok) 4069 use = find_use_as_address (PATTERN (insn), reg, 0); 4070 if (post_ok && (use == 0 || use == (rtx) (size_t) 1)) 4071 { 4072 use = find_use_as_address (PATTERN (insn), reg, -amount); 4073 do_post = 1; 4074 } 4075 4076 if (use == 0 || use == (rtx) (size_t) 1) 4077 return 0; 4078 4079 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount)) 4080 return 0; 4081 4082 /* See if this combination of instruction and addressing mode exists. */ 4083 if (! validate_change (insn, &XEXP (use, 0), 4084 gen_rtx_fmt_e (amount > 0 4085 ? (do_post ? POST_INC : PRE_INC) 4086 : (do_post ? POST_DEC : PRE_DEC), 4087 Pmode, reg), 0)) 4088 return 0; 4089 4090 /* Record that this insn now has an implicit side effect on X. */ 4091 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn)); 4092 return 1; 4093} 4094 4095#endif /* AUTO_INC_DEC */ 4096 4097/* Find the place in the rtx X where REG is used as a memory address. 4098 Return the MEM rtx that so uses it. 4099 If PLUSCONST is nonzero, search instead for a memory address equivalent to 4100 (plus REG (const_int PLUSCONST)). 4101 4102 If such an address does not appear, return 0. 4103 If REG appears more than once, or is used other than in such an address, 4104 return (rtx) 1. */ 4105 4106rtx 4107find_use_as_address (x, reg, plusconst) 4108 rtx x; 4109 rtx reg; 4110 HOST_WIDE_INT plusconst; 4111{ 4112 enum rtx_code code = GET_CODE (x); 4113 const char * const fmt = GET_RTX_FORMAT (code); 4114 int i; 4115 rtx value = 0; 4116 rtx tem; 4117 4118 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0) 4119 return x; 4120 4121 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS 4122 && XEXP (XEXP (x, 0), 0) == reg 4123 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT 4124 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst) 4125 return x; 4126 4127 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT) 4128 { 4129 /* If REG occurs inside a MEM used in a bit-field reference, 4130 that is unacceptable. */ 4131 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0) 4132 return (rtx) (size_t) 1; 4133 } 4134 4135 if (x == reg) 4136 return (rtx) (size_t) 1; 4137 4138 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 4139 { 4140 if (fmt[i] == 'e') 4141 { 4142 tem = find_use_as_address (XEXP (x, i), reg, plusconst); 4143 if (value == 0) 4144 value = tem; 4145 else if (tem != 0) 4146 return (rtx) (size_t) 1; 4147 } 4148 else if (fmt[i] == 'E') 4149 { 4150 int j; 4151 for (j = XVECLEN (x, i) - 1; j >= 0; j--) 4152 { 4153 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst); 4154 if (value == 0) 4155 value = tem; 4156 else if (tem != 0) 4157 return (rtx) (size_t) 1; 4158 } 4159 } 4160 } 4161 4162 return value; 4163} 4164 4165/* Write information about registers and basic blocks into FILE. 4166 This is part of making a debugging dump. */ 4167 4168void 4169dump_regset (r, outf) 4170 regset r; 4171 FILE *outf; 4172{ 4173 int i; 4174 if (r == NULL) 4175 { 4176 fputs (" (nil)", outf); 4177 return; 4178 } 4179 4180 EXECUTE_IF_SET_IN_REG_SET (r, 0, i, 4181 { 4182 fprintf (outf, " %d", i); 4183 if (i < FIRST_PSEUDO_REGISTER) 4184 fprintf (outf, " [%s]", 4185 reg_names[i]); 4186 }); 4187} 4188 4189/* Print a human-reaable representation of R on the standard error 4190 stream. This function is designed to be used from within the 4191 debugger. */ 4192 4193void 4194debug_regset (r) 4195 regset r; 4196{ 4197 dump_regset (r, stderr); 4198 putc ('\n', stderr); 4199} 4200 4201/* Recompute register set/reference counts immediately prior to register 4202 allocation. 4203 4204 This avoids problems with set/reference counts changing to/from values 4205 which have special meanings to the register allocators. 4206 4207 Additionally, the reference counts are the primary component used by the 4208 register allocators to prioritize pseudos for allocation to hard regs. 4209 More accurate reference counts generally lead to better register allocation. 4210 4211 F is the first insn to be scanned. 4212 4213 LOOP_STEP denotes how much loop_depth should be incremented per 4214 loop nesting level in order to increase the ref count more for 4215 references in a loop. 4216 4217 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and 4218 possibly other information which is used by the register allocators. */ 4219 4220void 4221recompute_reg_usage (f, loop_step) 4222 rtx f ATTRIBUTE_UNUSED; 4223 int loop_step ATTRIBUTE_UNUSED; 4224{ 4225 allocate_reg_life_data (); 4226 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO); 4227} 4228 4229/* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of 4230 blocks. If BLOCKS is NULL, assume the universal set. Returns a count 4231 of the number of registers that died. */ 4232 4233int 4234count_or_remove_death_notes (blocks, kill) 4235 sbitmap blocks; 4236 int kill; 4237{ 4238 int i, count = 0; 4239 4240 for (i = n_basic_blocks - 1; i >= 0; --i) 4241 { 4242 basic_block bb; 4243 rtx insn; 4244 4245 if (blocks && ! TEST_BIT (blocks, i)) 4246 continue; 4247 4248 bb = BASIC_BLOCK (i); 4249 4250 for (insn = bb->head;; insn = NEXT_INSN (insn)) 4251 { 4252 if (INSN_P (insn)) 4253 { 4254 rtx *pprev = ®_NOTES (insn); 4255 rtx link = *pprev; 4256 4257 while (link) 4258 { 4259 switch (REG_NOTE_KIND (link)) 4260 { 4261 case REG_DEAD: 4262 if (GET_CODE (XEXP (link, 0)) == REG) 4263 { 4264 rtx reg = XEXP (link, 0); 4265 int n; 4266 4267 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER) 4268 n = 1; 4269 else 4270 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg)); 4271 count += n; 4272 } 4273 /* Fall through. */ 4274 4275 case REG_UNUSED: 4276 if (kill) 4277 { 4278 rtx next = XEXP (link, 1); 4279 free_EXPR_LIST_node (link); 4280 *pprev = link = next; 4281 break; 4282 } 4283 /* Fall through. */ 4284 4285 default: 4286 pprev = &XEXP (link, 1); 4287 link = *pprev; 4288 break; 4289 } 4290 } 4291 } 4292 4293 if (insn == bb->end) 4294 break; 4295 } 4296 } 4297 4298 return count; 4299} 4300/* Clear LOG_LINKS fields of insns in a selected blocks or whole chain 4301 if blocks is NULL. */ 4302 4303static void 4304clear_log_links (blocks) 4305 sbitmap blocks; 4306{ 4307 rtx insn; 4308 int i; 4309 4310 if (!blocks) 4311 { 4312 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) 4313 if (INSN_P (insn)) 4314 free_INSN_LIST_list (&LOG_LINKS (insn)); 4315 } 4316 else 4317 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i, 4318 { 4319 basic_block bb = BASIC_BLOCK (i); 4320 4321 for (insn = bb->head; insn != NEXT_INSN (bb->end); 4322 insn = NEXT_INSN (insn)) 4323 if (INSN_P (insn)) 4324 free_INSN_LIST_list (&LOG_LINKS (insn)); 4325 }); 4326} 4327 4328/* Given a register bitmap, turn on the bits in a HARD_REG_SET that 4329 correspond to the hard registers, if any, set in that map. This 4330 could be done far more efficiently by having all sorts of special-cases 4331 with moving single words, but probably isn't worth the trouble. */ 4332 4333void 4334reg_set_to_hard_reg_set (to, from) 4335 HARD_REG_SET *to; 4336 bitmap from; 4337{ 4338 int i; 4339 4340 EXECUTE_IF_SET_IN_BITMAP 4341 (from, 0, i, 4342 { 4343 if (i >= FIRST_PSEUDO_REGISTER) 4344 return; 4345 SET_HARD_REG_BIT (*to, i); 4346 }); 4347} 4348