flow.c revision 161651
1/* Data flow analysis for GNU compiler. 2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 3 1999, 2000, 2001, 2002, 2003, 2004 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, REG_N_THROWING_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 "coretypes.h" 124#include "tm.h" 125#include "tree.h" 126#include "rtl.h" 127#include "tm_p.h" 128#include "hard-reg-set.h" 129#include "basic-block.h" 130#include "insn-config.h" 131#include "regs.h" 132#include "flags.h" 133#include "output.h" 134#include "function.h" 135#include "except.h" 136#include "toplev.h" 137#include "recog.h" 138#include "expr.h" 139#include "timevar.h" 140 141#include "obstack.h" 142#include "splay-tree.h" 143 144#ifndef HAVE_epilogue 145#define HAVE_epilogue 0 146#endif 147#ifndef HAVE_prologue 148#define HAVE_prologue 0 149#endif 150#ifndef HAVE_sibcall_epilogue 151#define HAVE_sibcall_epilogue 0 152#endif 153 154#ifndef EPILOGUE_USES 155#define EPILOGUE_USES(REGNO) 0 156#endif 157#ifndef EH_USES 158#define EH_USES(REGNO) 0 159#endif 160 161#ifdef HAVE_conditional_execution 162#ifndef REVERSE_CONDEXEC_PREDICATES_P 163#define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y)) 164#endif 165#endif 166 167/* Nonzero if the second flow pass has completed. */ 168int flow2_completed; 169 170/* Maximum register number used in this function, plus one. */ 171 172int max_regno; 173 174/* Indexed by n, giving various register information */ 175 176varray_type reg_n_info; 177 178/* Size of a regset for the current function, 179 in (1) bytes and (2) elements. */ 180 181int regset_bytes; 182int regset_size; 183 184/* Regset of regs live when calls to `setjmp'-like functions happen. */ 185/* ??? Does this exist only for the setjmp-clobbered warning message? */ 186 187regset regs_live_at_setjmp; 188 189/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers 190 that have to go in the same hard reg. 191 The first two regs in the list are a pair, and the next two 192 are another pair, etc. */ 193rtx regs_may_share; 194 195/* Callback that determines if it's ok for a function to have no 196 noreturn attribute. */ 197int (*lang_missing_noreturn_ok_p) (tree); 198 199/* Set of registers that may be eliminable. These are handled specially 200 in updating regs_ever_live. */ 201 202static HARD_REG_SET elim_reg_set; 203 204/* Holds information for tracking conditional register life information. */ 205struct reg_cond_life_info 206{ 207 /* A boolean expression of conditions under which a register is dead. */ 208 rtx condition; 209 /* Conditions under which a register is dead at the basic block end. */ 210 rtx orig_condition; 211 212 /* A boolean expression of conditions under which a register has been 213 stored into. */ 214 rtx stores; 215 216 /* ??? Could store mask of bytes that are dead, so that we could finally 217 track lifetimes of multi-word registers accessed via subregs. */ 218}; 219 220/* For use in communicating between propagate_block and its subroutines. 221 Holds all information needed to compute life and def-use information. */ 222 223struct propagate_block_info 224{ 225 /* The basic block we're considering. */ 226 basic_block bb; 227 228 /* Bit N is set if register N is conditionally or unconditionally live. */ 229 regset reg_live; 230 231 /* Bit N is set if register N is set this insn. */ 232 regset new_set; 233 234 /* Element N is the next insn that uses (hard or pseudo) register N 235 within the current basic block; or zero, if there is no such insn. */ 236 rtx *reg_next_use; 237 238 /* Contains a list of all the MEMs we are tracking for dead store 239 elimination. */ 240 rtx mem_set_list; 241 242 /* If non-null, record the set of registers set unconditionally in the 243 basic block. */ 244 regset local_set; 245 246 /* If non-null, record the set of registers set conditionally in the 247 basic block. */ 248 regset cond_local_set; 249 250#ifdef HAVE_conditional_execution 251 /* Indexed by register number, holds a reg_cond_life_info for each 252 register that is not unconditionally live or dead. */ 253 splay_tree reg_cond_dead; 254 255 /* Bit N is set if register N is in an expression in reg_cond_dead. */ 256 regset reg_cond_reg; 257#endif 258 259 /* The length of mem_set_list. */ 260 int mem_set_list_len; 261 262 /* Nonzero if the value of CC0 is live. */ 263 int cc0_live; 264 265 /* Flags controlling the set of information propagate_block collects. */ 266 int flags; 267}; 268 269/* Number of dead insns removed. */ 270static int ndead; 271 272/* Maximum length of pbi->mem_set_list before we start dropping 273 new elements on the floor. */ 274#define MAX_MEM_SET_LIST_LEN 100 275 276/* Forward declarations */ 277static int verify_wide_reg_1 (rtx *, void *); 278static void verify_wide_reg (int, basic_block); 279static void verify_local_live_at_start (regset, basic_block); 280static void notice_stack_pointer_modification_1 (rtx, rtx, void *); 281static void notice_stack_pointer_modification (rtx); 282static void mark_reg (rtx, void *); 283static void mark_regs_live_at_end (regset); 284static void calculate_global_regs_live (sbitmap, sbitmap, int); 285static void propagate_block_delete_insn (rtx); 286static rtx propagate_block_delete_libcall (rtx, rtx); 287static int insn_dead_p (struct propagate_block_info *, rtx, int, rtx); 288static int libcall_dead_p (struct propagate_block_info *, rtx, rtx); 289static void mark_set_regs (struct propagate_block_info *, rtx, rtx); 290static void mark_set_1 (struct propagate_block_info *, enum rtx_code, rtx, 291 rtx, rtx, int); 292static int find_regno_partial (rtx *, void *); 293 294#ifdef HAVE_conditional_execution 295static int mark_regno_cond_dead (struct propagate_block_info *, int, rtx); 296static void free_reg_cond_life_info (splay_tree_value); 297static int flush_reg_cond_reg_1 (splay_tree_node, void *); 298static void flush_reg_cond_reg (struct propagate_block_info *, int); 299static rtx elim_reg_cond (rtx, unsigned int); 300static rtx ior_reg_cond (rtx, rtx, int); 301static rtx not_reg_cond (rtx); 302static rtx and_reg_cond (rtx, rtx, int); 303#endif 304#ifdef AUTO_INC_DEC 305static void attempt_auto_inc (struct propagate_block_info *, rtx, rtx, rtx, 306 rtx, rtx); 307static void find_auto_inc (struct propagate_block_info *, rtx, rtx); 308static int try_pre_increment_1 (struct propagate_block_info *, rtx); 309static int try_pre_increment (rtx, rtx, HOST_WIDE_INT); 310#endif 311static void mark_used_reg (struct propagate_block_info *, rtx, rtx, rtx); 312static void mark_used_regs (struct propagate_block_info *, rtx, rtx, rtx); 313void debug_flow_info (void); 314static void add_to_mem_set_list (struct propagate_block_info *, rtx); 315static int invalidate_mems_from_autoinc (rtx *, void *); 316static void invalidate_mems_from_set (struct propagate_block_info *, rtx); 317static void clear_log_links (sbitmap); 318static int count_or_remove_death_notes_bb (basic_block, int); 319 320 321void 322check_function_return_warnings (void) 323{ 324 if (warn_missing_noreturn 325 && !TREE_THIS_VOLATILE (cfun->decl) 326 && EXIT_BLOCK_PTR->pred == NULL 327 && (lang_missing_noreturn_ok_p 328 && !lang_missing_noreturn_ok_p (cfun->decl))) 329 warning ("function might be possible candidate for attribute `noreturn'"); 330 331 /* If we have a path to EXIT, then we do return. */ 332 if (TREE_THIS_VOLATILE (cfun->decl) 333 && EXIT_BLOCK_PTR->pred != NULL) 334 warning ("`noreturn' function does return"); 335 336 /* If the clobber_return_insn appears in some basic block, then we 337 do reach the end without returning a value. */ 338 else if (warn_return_type 339 && cfun->x_clobber_return_insn != NULL 340 && EXIT_BLOCK_PTR->pred != NULL) 341 { 342 int max_uid = get_max_uid (); 343 344 /* If clobber_return_insn was excised by jump1, then renumber_insns 345 can make max_uid smaller than the number still recorded in our rtx. 346 That's fine, since this is a quick way of verifying that the insn 347 is no longer in the chain. */ 348 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid) 349 { 350 rtx insn; 351 352 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) 353 if (insn == cfun->x_clobber_return_insn) 354 { 355 warning ("control reaches end of non-void function"); 356 break; 357 } 358 } 359 } 360} 361 362/* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK 363 note associated with the BLOCK. */ 364 365rtx 366first_insn_after_basic_block_note (basic_block block) 367{ 368 rtx insn; 369 370 /* Get the first instruction in the block. */ 371 insn = BB_HEAD (block); 372 373 if (insn == NULL_RTX) 374 return NULL_RTX; 375 if (GET_CODE (insn) == CODE_LABEL) 376 insn = NEXT_INSN (insn); 377 if (!NOTE_INSN_BASIC_BLOCK_P (insn)) 378 abort (); 379 380 return NEXT_INSN (insn); 381} 382 383/* Perform data flow analysis. 384 F is the first insn of the function; FLAGS is a set of PROP_* flags 385 to be used in accumulating flow info. */ 386 387void 388life_analysis (rtx f, FILE *file, int flags) 389{ 390#ifdef ELIMINABLE_REGS 391 int i; 392 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS; 393#endif 394 395 /* Record which registers will be eliminated. We use this in 396 mark_used_regs. */ 397 398 CLEAR_HARD_REG_SET (elim_reg_set); 399 400#ifdef ELIMINABLE_REGS 401 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++) 402 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from); 403#else 404 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM); 405#endif 406 407 408#ifdef CANNOT_CHANGE_MODE_CLASS 409 if (flags & PROP_REG_INFO) 410 init_subregs_of_mode (); 411#endif 412 413 if (! optimize) 414 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES); 415 416 /* The post-reload life analysis have (on a global basis) the same 417 registers live as was computed by reload itself. elimination 418 Otherwise offsets and such may be incorrect. 419 420 Reload will make some registers as live even though they do not 421 appear in the rtl. 422 423 We don't want to create new auto-incs after reload, since they 424 are unlikely to be useful and can cause problems with shared 425 stack slots. */ 426 if (reload_completed) 427 flags &= ~(PROP_REG_INFO | PROP_AUTOINC); 428 429 /* We want alias analysis information for local dead store elimination. */ 430 if (optimize && (flags & PROP_SCAN_DEAD_STORES)) 431 init_alias_analysis (); 432 433 /* Always remove no-op moves. Do this before other processing so 434 that we don't have to keep re-scanning them. */ 435 delete_noop_moves (f); 436 437 /* Some targets can emit simpler epilogues if they know that sp was 438 not ever modified during the function. After reload, of course, 439 we've already emitted the epilogue so there's no sense searching. */ 440 if (! reload_completed) 441 notice_stack_pointer_modification (f); 442 443 /* Allocate and zero out data structures that will record the 444 data from lifetime analysis. */ 445 allocate_reg_life_data (); 446 allocate_bb_life_data (); 447 448 /* Find the set of registers live on function exit. */ 449 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start); 450 451 /* "Update" life info from zero. It'd be nice to begin the 452 relaxation with just the exit and noreturn blocks, but that set 453 is not immediately handy. */ 454 455 if (flags & PROP_REG_INFO) 456 { 457 memset (regs_ever_live, 0, sizeof (regs_ever_live)); 458 memset (regs_asm_clobbered, 0, sizeof (regs_asm_clobbered)); 459 } 460 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags); 461 462 /* Clean up. */ 463 if (optimize && (flags & PROP_SCAN_DEAD_STORES)) 464 end_alias_analysis (); 465 466 if (file) 467 dump_flow_info (file); 468 469 free_basic_block_vars (1); 470 471 /* Removing dead insns should've made jumptables really dead. */ 472 delete_dead_jumptables (); 473} 474 475/* A subroutine of verify_wide_reg, called through for_each_rtx. 476 Search for REGNO. If found, return 2 if it is not wider than 477 word_mode. */ 478 479static int 480verify_wide_reg_1 (rtx *px, void *pregno) 481{ 482 rtx x = *px; 483 unsigned int regno = *(int *) pregno; 484 485 if (GET_CODE (x) == REG && REGNO (x) == regno) 486 { 487 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD) 488 return 2; 489 return 1; 490 } 491 return 0; 492} 493 494/* A subroutine of verify_local_live_at_start. Search through insns 495 of BB looking for register REGNO. */ 496 497static void 498verify_wide_reg (int regno, basic_block bb) 499{ 500 rtx head = BB_HEAD (bb), end = BB_END (bb); 501 502 while (1) 503 { 504 if (INSN_P (head)) 505 { 506 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no); 507 if (r == 1) 508 return; 509 if (r == 2) 510 break; 511 } 512 if (head == end) 513 break; 514 head = NEXT_INSN (head); 515 } 516 517 if (rtl_dump_file) 518 { 519 fprintf (rtl_dump_file, "Register %d died unexpectedly.\n", regno); 520 dump_bb (bb, rtl_dump_file); 521 } 522 abort (); 523} 524 525/* A subroutine of update_life_info. Verify that there are no untoward 526 changes in live_at_start during a local update. */ 527 528static void 529verify_local_live_at_start (regset new_live_at_start, basic_block bb) 530{ 531 if (reload_completed) 532 { 533 /* After reload, there are no pseudos, nor subregs of multi-word 534 registers. The regsets should exactly match. */ 535 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start)) 536 { 537 if (rtl_dump_file) 538 { 539 fprintf (rtl_dump_file, 540 "live_at_start mismatch in bb %d, aborting\nNew:\n", 541 bb->index); 542 debug_bitmap_file (rtl_dump_file, new_live_at_start); 543 fputs ("Old:\n", rtl_dump_file); 544 dump_bb (bb, rtl_dump_file); 545 } 546 abort (); 547 } 548 } 549 else 550 { 551 int i; 552 553 /* Find the set of changed registers. */ 554 XOR_REG_SET (new_live_at_start, bb->global_live_at_start); 555 556 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i, 557 { 558 /* No registers should die. */ 559 if (REGNO_REG_SET_P (bb->global_live_at_start, i)) 560 { 561 if (rtl_dump_file) 562 { 563 fprintf (rtl_dump_file, 564 "Register %d died unexpectedly.\n", i); 565 dump_bb (bb, rtl_dump_file); 566 } 567 abort (); 568 } 569 570 /* Verify that the now-live register is wider than word_mode. */ 571 verify_wide_reg (i, bb); 572 }); 573 } 574} 575 576/* Updates life information starting with the basic blocks set in BLOCKS. 577 If BLOCKS is null, consider it to be the universal set. 578 579 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing, 580 we are only expecting local modifications to basic blocks. If we find 581 extra registers live at the beginning of a block, then we either killed 582 useful data, or we have a broken split that wants data not provided. 583 If we find registers removed from live_at_start, that means we have 584 a broken peephole that is killing a register it shouldn't. 585 586 ??? This is not true in one situation -- when a pre-reload splitter 587 generates subregs of a multi-word pseudo, current life analysis will 588 lose the kill. So we _can_ have a pseudo go live. How irritating. 589 590 It is also not true when a peephole decides that it doesn't need one 591 or more of the inputs. 592 593 Including PROP_REG_INFO does not properly refresh regs_ever_live 594 unless the caller resets it to zero. */ 595 596int 597update_life_info (sbitmap blocks, enum update_life_extent extent, int prop_flags) 598{ 599 regset tmp; 600 regset_head tmp_head; 601 int i; 602 int stabilized_prop_flags = prop_flags; 603 basic_block bb; 604 605 tmp = INITIALIZE_REG_SET (tmp_head); 606 ndead = 0; 607 608 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks) 609 ? TV_LIFE_UPDATE : TV_LIFE); 610 611 /* Changes to the CFG are only allowed when 612 doing a global update for the entire CFG. */ 613 if ((prop_flags & PROP_ALLOW_CFG_CHANGES) 614 && (extent == UPDATE_LIFE_LOCAL || blocks)) 615 abort (); 616 617 /* For a global update, we go through the relaxation process again. */ 618 if (extent != UPDATE_LIFE_LOCAL) 619 { 620 for ( ; ; ) 621 { 622 int changed = 0; 623 624 calculate_global_regs_live (blocks, blocks, 625 prop_flags & (PROP_SCAN_DEAD_CODE 626 | PROP_SCAN_DEAD_STORES 627 | PROP_ALLOW_CFG_CHANGES)); 628 629 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES)) 630 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES)) 631 break; 632 633 /* Removing dead code may allow the CFG to be simplified which 634 in turn may allow for further dead code detection / removal. */ 635 FOR_EACH_BB_REVERSE (bb) 636 { 637 COPY_REG_SET (tmp, bb->global_live_at_end); 638 changed |= propagate_block (bb, tmp, NULL, NULL, 639 prop_flags & (PROP_SCAN_DEAD_CODE 640 | PROP_SCAN_DEAD_STORES 641 | PROP_KILL_DEAD_CODE)); 642 } 643 644 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to 645 subsequent propagate_block calls, since removing or acting as 646 removing dead code can affect global register liveness, which 647 is supposed to be finalized for this call after this loop. */ 648 stabilized_prop_flags 649 &= ~(PROP_SCAN_DEAD_CODE | PROP_SCAN_DEAD_STORES 650 | PROP_KILL_DEAD_CODE); 651 652 if (! changed) 653 break; 654 655 /* We repeat regardless of what cleanup_cfg says. If there were 656 instructions deleted above, that might have been only a 657 partial improvement (see MAX_MEM_SET_LIST_LEN usage). 658 Further improvement may be possible. */ 659 cleanup_cfg (CLEANUP_EXPENSIVE); 660 661 /* Zap the life information from the last round. If we don't 662 do this, we can wind up with registers that no longer appear 663 in the code being marked live at entry, which twiggs bogus 664 warnings from regno_uninitialized. */ 665 FOR_EACH_BB (bb) 666 { 667 CLEAR_REG_SET (bb->global_live_at_start); 668 CLEAR_REG_SET (bb->global_live_at_end); 669 } 670 } 671 672 /* If asked, remove notes from the blocks we'll update. */ 673 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES) 674 count_or_remove_death_notes (blocks, 1); 675 } 676 677 /* Clear log links in case we are asked to (re)compute them. */ 678 if (prop_flags & PROP_LOG_LINKS) 679 clear_log_links (blocks); 680 681 if (blocks) 682 { 683 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i, 684 { 685 bb = BASIC_BLOCK (i); 686 687 COPY_REG_SET (tmp, bb->global_live_at_end); 688 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags); 689 690 if (extent == UPDATE_LIFE_LOCAL) 691 verify_local_live_at_start (tmp, bb); 692 }); 693 } 694 else 695 { 696 FOR_EACH_BB_REVERSE (bb) 697 { 698 COPY_REG_SET (tmp, bb->global_live_at_end); 699 700 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags); 701 702 if (extent == UPDATE_LIFE_LOCAL) 703 verify_local_live_at_start (tmp, bb); 704 } 705 } 706 707 FREE_REG_SET (tmp); 708 709 if (prop_flags & PROP_REG_INFO) 710 { 711 /* The only pseudos that are live at the beginning of the function 712 are those that were not set anywhere in the function. local-alloc 713 doesn't know how to handle these correctly, so mark them as not 714 local to any one basic block. */ 715 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end, 716 FIRST_PSEUDO_REGISTER, i, 717 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; }); 718 719 /* We have a problem with any pseudoreg that lives across the setjmp. 720 ANSI says that if a user variable does not change in value between 721 the setjmp and the longjmp, then the longjmp preserves it. This 722 includes longjmp from a place where the pseudo appears dead. 723 (In principle, the value still exists if it is in scope.) 724 If the pseudo goes in a hard reg, some other value may occupy 725 that hard reg where this pseudo is dead, thus clobbering the pseudo. 726 Conclusion: such a pseudo must not go in a hard reg. */ 727 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp, 728 FIRST_PSEUDO_REGISTER, i, 729 { 730 if (regno_reg_rtx[i] != 0) 731 { 732 REG_LIVE_LENGTH (i) = -1; 733 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN; 734 } 735 }); 736 } 737 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks) 738 ? TV_LIFE_UPDATE : TV_LIFE); 739 if (ndead && rtl_dump_file) 740 fprintf (rtl_dump_file, "deleted %i dead insns\n", ndead); 741 return ndead; 742} 743 744/* Update life information in all blocks where BB_DIRTY is set. */ 745 746int 747update_life_info_in_dirty_blocks (enum update_life_extent extent, int prop_flags) 748{ 749 sbitmap update_life_blocks = sbitmap_alloc (last_basic_block); 750 int n = 0; 751 basic_block bb; 752 int retval = 0; 753 754 sbitmap_zero (update_life_blocks); 755 FOR_EACH_BB (bb) 756 { 757 if (extent == UPDATE_LIFE_LOCAL) 758 { 759 if (bb->flags & BB_DIRTY) 760 { 761 SET_BIT (update_life_blocks, bb->index); 762 n++; 763 } 764 } 765 else 766 { 767 /* ??? Bootstrap with -march=pentium4 fails to terminate 768 with only a partial life update. */ 769 SET_BIT (update_life_blocks, bb->index); 770 if (bb->flags & BB_DIRTY) 771 n++; 772 } 773 } 774 775 if (n) 776 retval = update_life_info (update_life_blocks, extent, prop_flags); 777 778 sbitmap_free (update_life_blocks); 779 return retval; 780} 781 782/* Free the variables allocated by find_basic_blocks. 783 784 KEEP_HEAD_END_P is nonzero if basic_block_info is not to be freed. */ 785 786void 787free_basic_block_vars (int keep_head_end_p) 788{ 789 if (! keep_head_end_p) 790 { 791 if (basic_block_info) 792 { 793 clear_edges (); 794 VARRAY_FREE (basic_block_info); 795 } 796 n_basic_blocks = 0; 797 last_basic_block = 0; 798 799 ENTRY_BLOCK_PTR->aux = NULL; 800 ENTRY_BLOCK_PTR->global_live_at_end = NULL; 801 EXIT_BLOCK_PTR->aux = NULL; 802 EXIT_BLOCK_PTR->global_live_at_start = NULL; 803 } 804} 805 806/* Delete any insns that copy a register to itself. */ 807 808int 809delete_noop_moves (rtx f ATTRIBUTE_UNUSED) 810{ 811 rtx insn, next; 812 basic_block bb; 813 int nnoops = 0; 814 815 FOR_EACH_BB (bb) 816 { 817 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); insn = next) 818 { 819 next = NEXT_INSN (insn); 820 if (INSN_P (insn) && noop_move_p (insn)) 821 { 822 rtx note; 823 824 /* If we're about to remove the first insn of a libcall 825 then move the libcall note to the next real insn and 826 update the retval note. */ 827 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX)) 828 && XEXP (note, 0) != insn) 829 { 830 rtx new_libcall_insn = next_real_insn (insn); 831 rtx retval_note = find_reg_note (XEXP (note, 0), 832 REG_RETVAL, NULL_RTX); 833 REG_NOTES (new_libcall_insn) 834 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0), 835 REG_NOTES (new_libcall_insn)); 836 XEXP (retval_note, 0) = new_libcall_insn; 837 } 838 839 delete_insn_and_edges (insn); 840 nnoops++; 841 } 842 } 843 } 844 if (nnoops && rtl_dump_file) 845 fprintf (rtl_dump_file, "deleted %i noop moves", nnoops); 846 return nnoops; 847} 848 849/* Delete any jump tables never referenced. We can't delete them at the 850 time of removing tablejump insn as they are referenced by the preceding 851 insns computing the destination, so we delay deleting and garbagecollect 852 them once life information is computed. */ 853void 854delete_dead_jumptables (void) 855{ 856 rtx insn, next; 857 for (insn = get_insns (); insn; insn = next) 858 { 859 next = NEXT_INSN (insn); 860 if (GET_CODE (insn) == CODE_LABEL 861 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn) 862 && GET_CODE (next) == JUMP_INSN 863 && (GET_CODE (PATTERN (next)) == ADDR_VEC 864 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) 865 { 866 if (rtl_dump_file) 867 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn)); 868 delete_insn (NEXT_INSN (insn)); 869 delete_insn (insn); 870 next = NEXT_INSN (next); 871 } 872 } 873} 874 875/* Determine if the stack pointer is constant over the life of the function. 876 Only useful before prologues have been emitted. */ 877 878static void 879notice_stack_pointer_modification_1 (rtx x, rtx pat ATTRIBUTE_UNUSED, 880 void *data ATTRIBUTE_UNUSED) 881{ 882 if (x == stack_pointer_rtx 883 /* The stack pointer is only modified indirectly as the result 884 of a push until later in flow. See the comments in rtl.texi 885 regarding Embedded Side-Effects on Addresses. */ 886 || (GET_CODE (x) == MEM 887 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a' 888 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx)) 889 current_function_sp_is_unchanging = 0; 890} 891 892static void 893notice_stack_pointer_modification (rtx f) 894{ 895 rtx insn; 896 897 /* Assume that the stack pointer is unchanging if alloca hasn't 898 been used. */ 899 current_function_sp_is_unchanging = !current_function_calls_alloca; 900 if (! current_function_sp_is_unchanging) 901 return; 902 903 for (insn = f; insn; insn = NEXT_INSN (insn)) 904 { 905 if (INSN_P (insn)) 906 { 907 /* Check if insn modifies the stack pointer. */ 908 note_stores (PATTERN (insn), notice_stack_pointer_modification_1, 909 NULL); 910 if (! current_function_sp_is_unchanging) 911 return; 912 } 913 } 914} 915 916/* Mark a register in SET. Hard registers in large modes get all 917 of their component registers set as well. */ 918 919static void 920mark_reg (rtx reg, void *xset) 921{ 922 regset set = (regset) xset; 923 int regno = REGNO (reg); 924 925 if (GET_MODE (reg) == BLKmode) 926 abort (); 927 928 SET_REGNO_REG_SET (set, regno); 929 if (regno < FIRST_PSEUDO_REGISTER) 930 { 931 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg)); 932 while (--n > 0) 933 SET_REGNO_REG_SET (set, regno + n); 934 } 935} 936 937/* Mark those regs which are needed at the end of the function as live 938 at the end of the last basic block. */ 939 940static void 941mark_regs_live_at_end (regset set) 942{ 943 unsigned int i; 944 945 /* If exiting needs the right stack value, consider the stack pointer 946 live at the end of the function. */ 947 if ((HAVE_epilogue && epilogue_completed) 948 || ! EXIT_IGNORE_STACK 949 || (! FRAME_POINTER_REQUIRED 950 && ! current_function_calls_alloca 951 && flag_omit_frame_pointer) 952 || current_function_sp_is_unchanging) 953 { 954 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM); 955 } 956 957 /* Mark the frame pointer if needed at the end of the function. If 958 we end up eliminating it, it will be removed from the live list 959 of each basic block by reload. */ 960 961 if (! reload_completed || frame_pointer_needed) 962 { 963 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM); 964#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 965 /* If they are different, also mark the hard frame pointer as live. */ 966 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM)) 967 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM); 968#endif 969 } 970 971#ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED 972 /* Many architectures have a GP register even without flag_pic. 973 Assume the pic register is not in use, or will be handled by 974 other means, if it is not fixed. */ 975 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM 976 && fixed_regs[PIC_OFFSET_TABLE_REGNUM]) 977 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM); 978#endif 979 980 /* Mark all global registers, and all registers used by the epilogue 981 as being live at the end of the function since they may be 982 referenced by our caller. */ 983 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 984 if (global_regs[i] || EPILOGUE_USES (i)) 985 SET_REGNO_REG_SET (set, i); 986 987 if (HAVE_epilogue && epilogue_completed) 988 { 989 /* Mark all call-saved registers that we actually used. */ 990 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 991 if (regs_ever_live[i] && ! LOCAL_REGNO (i) 992 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) 993 SET_REGNO_REG_SET (set, i); 994 } 995 996#ifdef EH_RETURN_DATA_REGNO 997 /* Mark the registers that will contain data for the handler. */ 998 if (reload_completed && current_function_calls_eh_return) 999 for (i = 0; ; ++i) 1000 { 1001 unsigned regno = EH_RETURN_DATA_REGNO(i); 1002 if (regno == INVALID_REGNUM) 1003 break; 1004 SET_REGNO_REG_SET (set, regno); 1005 } 1006#endif 1007#ifdef EH_RETURN_STACKADJ_RTX 1008 if ((! HAVE_epilogue || ! epilogue_completed) 1009 && current_function_calls_eh_return) 1010 { 1011 rtx tmp = EH_RETURN_STACKADJ_RTX; 1012 if (tmp && REG_P (tmp)) 1013 mark_reg (tmp, set); 1014 } 1015#endif 1016#ifdef EH_RETURN_HANDLER_RTX 1017 if ((! HAVE_epilogue || ! epilogue_completed) 1018 && current_function_calls_eh_return) 1019 { 1020 rtx tmp = EH_RETURN_HANDLER_RTX; 1021 if (tmp && REG_P (tmp)) 1022 mark_reg (tmp, set); 1023 } 1024#endif 1025 1026 /* Mark function return value. */ 1027 diddle_return_value (mark_reg, set); 1028} 1029 1030/* Propagate global life info around the graph of basic blocks. Begin 1031 considering blocks with their corresponding bit set in BLOCKS_IN. 1032 If BLOCKS_IN is null, consider it the universal set. 1033 1034 BLOCKS_OUT is set for every block that was changed. */ 1035 1036static void 1037calculate_global_regs_live (sbitmap blocks_in, sbitmap blocks_out, int flags) 1038{ 1039 basic_block *queue, *qhead, *qtail, *qend, bb; 1040 regset tmp, new_live_at_end, invalidated_by_call; 1041 regset_head tmp_head, invalidated_by_call_head; 1042 regset_head new_live_at_end_head; 1043 int i; 1044 1045 /* Some passes used to forget clear aux field of basic block causing 1046 sick behavior here. */ 1047#ifdef ENABLE_CHECKING 1048 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) 1049 if (bb->aux) 1050 abort (); 1051#endif 1052 1053 tmp = INITIALIZE_REG_SET (tmp_head); 1054 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head); 1055 invalidated_by_call = INITIALIZE_REG_SET (invalidated_by_call_head); 1056 1057 /* Inconveniently, this is only readily available in hard reg set form. */ 1058 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) 1059 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) 1060 SET_REGNO_REG_SET (invalidated_by_call, i); 1061 1062 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one 1063 because the `head == tail' style test for an empty queue doesn't 1064 work with a full queue. */ 1065 queue = xmalloc ((n_basic_blocks + 2) * sizeof (*queue)); 1066 qtail = queue; 1067 qhead = qend = queue + n_basic_blocks + 2; 1068 1069 /* Queue the blocks set in the initial mask. Do this in reverse block 1070 number order so that we are more likely for the first round to do 1071 useful work. We use AUX non-null to flag that the block is queued. */ 1072 if (blocks_in) 1073 { 1074 FOR_EACH_BB (bb) 1075 if (TEST_BIT (blocks_in, bb->index)) 1076 { 1077 *--qhead = bb; 1078 bb->aux = bb; 1079 } 1080 } 1081 else 1082 { 1083 FOR_EACH_BB (bb) 1084 { 1085 *--qhead = bb; 1086 bb->aux = bb; 1087 } 1088 } 1089 1090 /* We clean aux when we remove the initially-enqueued bbs, but we 1091 don't enqueue ENTRY and EXIT initially, so clean them upfront and 1092 unconditionally. */ 1093 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL; 1094 1095 if (blocks_out) 1096 sbitmap_zero (blocks_out); 1097 1098 /* We work through the queue until there are no more blocks. What 1099 is live at the end of this block is precisely the union of what 1100 is live at the beginning of all its successors. So, we set its 1101 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field 1102 for its successors. Then, we compute GLOBAL_LIVE_AT_START for 1103 this block by walking through the instructions in this block in 1104 reverse order and updating as we go. If that changed 1105 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the 1106 queue; they will now need to recalculate GLOBAL_LIVE_AT_END. 1107 1108 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START 1109 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it 1110 must either be live at the end of the block, or used within the 1111 block. In the latter case, it will certainly never disappear 1112 from GLOBAL_LIVE_AT_START. In the former case, the register 1113 could go away only if it disappeared from GLOBAL_LIVE_AT_START 1114 for one of the successor blocks. By induction, that cannot 1115 occur. */ 1116 while (qhead != qtail) 1117 { 1118 int rescan, changed; 1119 basic_block bb; 1120 edge e; 1121 1122 bb = *qhead++; 1123 if (qhead == qend) 1124 qhead = queue; 1125 bb->aux = NULL; 1126 1127 /* Begin by propagating live_at_start from the successor blocks. */ 1128 CLEAR_REG_SET (new_live_at_end); 1129 1130 if (bb->succ) 1131 for (e = bb->succ; e; e = e->succ_next) 1132 { 1133 basic_block sb = e->dest; 1134 1135 /* Call-clobbered registers die across exception and 1136 call edges. */ 1137 /* ??? Abnormal call edges ignored for the moment, as this gets 1138 confused by sibling call edges, which crashes reg-stack. */ 1139 if (e->flags & EDGE_EH) 1140 { 1141 bitmap_operation (tmp, sb->global_live_at_start, 1142 invalidated_by_call, BITMAP_AND_COMPL); 1143 IOR_REG_SET (new_live_at_end, tmp); 1144 } 1145 else 1146 IOR_REG_SET (new_live_at_end, sb->global_live_at_start); 1147 1148 /* If a target saves one register in another (instead of on 1149 the stack) the save register will need to be live for EH. */ 1150 if (e->flags & EDGE_EH) 1151 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1152 if (EH_USES (i)) 1153 SET_REGNO_REG_SET (new_live_at_end, i); 1154 } 1155 else 1156 { 1157 /* This might be a noreturn function that throws. And 1158 even if it isn't, getting the unwind info right helps 1159 debugging. */ 1160 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1161 if (EH_USES (i)) 1162 SET_REGNO_REG_SET (new_live_at_end, i); 1163 } 1164 1165 /* The all-important stack pointer must always be live. */ 1166 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM); 1167 1168 /* Before reload, there are a few registers that must be forced 1169 live everywhere -- which might not already be the case for 1170 blocks within infinite loops. */ 1171 if (! reload_completed) 1172 { 1173 /* Any reference to any pseudo before reload is a potential 1174 reference of the frame pointer. */ 1175 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM); 1176 1177#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 1178 /* Pseudos with argument area equivalences may require 1179 reloading via the argument pointer. */ 1180 if (fixed_regs[ARG_POINTER_REGNUM]) 1181 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM); 1182#endif 1183 1184 /* Any constant, or pseudo with constant equivalences, may 1185 require reloading from memory using the pic register. */ 1186 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM 1187 && fixed_regs[PIC_OFFSET_TABLE_REGNUM]) 1188 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM); 1189 } 1190 1191 if (bb == ENTRY_BLOCK_PTR) 1192 { 1193 COPY_REG_SET (bb->global_live_at_end, new_live_at_end); 1194 continue; 1195 } 1196 1197 /* On our first pass through this block, we'll go ahead and continue. 1198 Recognize first pass by local_set NULL. On subsequent passes, we 1199 get to skip out early if live_at_end wouldn't have changed. */ 1200 1201 if (bb->local_set == NULL) 1202 { 1203 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1204 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1205 rescan = 1; 1206 } 1207 else 1208 { 1209 /* If any bits were removed from live_at_end, we'll have to 1210 rescan the block. This wouldn't be necessary if we had 1211 precalculated local_live, however with PROP_SCAN_DEAD_CODE 1212 local_live is really dependent on live_at_end. */ 1213 CLEAR_REG_SET (tmp); 1214 rescan = bitmap_operation (tmp, bb->global_live_at_end, 1215 new_live_at_end, BITMAP_AND_COMPL); 1216 1217 if (! rescan) 1218 { 1219 /* If any of the registers in the new live_at_end set are 1220 conditionally set in this basic block, we must rescan. 1221 This is because conditional lifetimes at the end of the 1222 block do not just take the live_at_end set into account, 1223 but also the liveness at the start of each successor 1224 block. We can miss changes in those sets if we only 1225 compare the new live_at_end against the previous one. */ 1226 CLEAR_REG_SET (tmp); 1227 rescan = bitmap_operation (tmp, new_live_at_end, 1228 bb->cond_local_set, BITMAP_AND); 1229 } 1230 1231 if (! rescan) 1232 { 1233 /* Find the set of changed bits. Take this opportunity 1234 to notice that this set is empty and early out. */ 1235 CLEAR_REG_SET (tmp); 1236 changed = bitmap_operation (tmp, bb->global_live_at_end, 1237 new_live_at_end, BITMAP_XOR); 1238 if (! changed) 1239 continue; 1240 1241 /* If any of the changed bits overlap with local_set, 1242 we'll have to rescan the block. Detect overlap by 1243 the AND with ~local_set turning off bits. */ 1244 rescan = bitmap_operation (tmp, tmp, bb->local_set, 1245 BITMAP_AND_COMPL); 1246 } 1247 } 1248 1249 /* Let our caller know that BB changed enough to require its 1250 death notes updated. */ 1251 if (blocks_out) 1252 SET_BIT (blocks_out, bb->index); 1253 1254 if (! rescan) 1255 { 1256 /* Add to live_at_start the set of all registers in 1257 new_live_at_end that aren't in the old live_at_end. */ 1258 1259 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end, 1260 BITMAP_AND_COMPL); 1261 COPY_REG_SET (bb->global_live_at_end, new_live_at_end); 1262 1263 changed = bitmap_operation (bb->global_live_at_start, 1264 bb->global_live_at_start, 1265 tmp, BITMAP_IOR); 1266 if (! changed) 1267 continue; 1268 } 1269 else 1270 { 1271 COPY_REG_SET (bb->global_live_at_end, new_live_at_end); 1272 1273 /* Rescan the block insn by insn to turn (a copy of) live_at_end 1274 into live_at_start. */ 1275 propagate_block (bb, new_live_at_end, bb->local_set, 1276 bb->cond_local_set, flags); 1277 1278 /* If live_at start didn't change, no need to go farther. */ 1279 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end)) 1280 continue; 1281 1282 COPY_REG_SET (bb->global_live_at_start, new_live_at_end); 1283 } 1284 1285 /* Queue all predecessors of BB so that we may re-examine 1286 their live_at_end. */ 1287 for (e = bb->pred; e; e = e->pred_next) 1288 { 1289 basic_block pb = e->src; 1290 if (pb->aux == NULL) 1291 { 1292 *qtail++ = pb; 1293 if (qtail == qend) 1294 qtail = queue; 1295 pb->aux = pb; 1296 } 1297 } 1298 } 1299 1300 FREE_REG_SET (tmp); 1301 FREE_REG_SET (new_live_at_end); 1302 FREE_REG_SET (invalidated_by_call); 1303 1304 if (blocks_out) 1305 { 1306 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i, 1307 { 1308 basic_block bb = BASIC_BLOCK (i); 1309 FREE_REG_SET (bb->local_set); 1310 FREE_REG_SET (bb->cond_local_set); 1311 }); 1312 } 1313 else 1314 { 1315 FOR_EACH_BB (bb) 1316 { 1317 FREE_REG_SET (bb->local_set); 1318 FREE_REG_SET (bb->cond_local_set); 1319 } 1320 } 1321 1322 free (queue); 1323} 1324 1325 1326/* This structure is used to pass parameters to and from the 1327 the function find_regno_partial(). It is used to pass in the 1328 register number we are looking, as well as to return any rtx 1329 we find. */ 1330 1331typedef struct { 1332 unsigned regno_to_find; 1333 rtx retval; 1334} find_regno_partial_param; 1335 1336 1337/* Find the rtx for the reg numbers specified in 'data' if it is 1338 part of an expression which only uses part of the register. Return 1339 it in the structure passed in. */ 1340static int 1341find_regno_partial (rtx *ptr, void *data) 1342{ 1343 find_regno_partial_param *param = (find_regno_partial_param *)data; 1344 unsigned reg = param->regno_to_find; 1345 param->retval = NULL_RTX; 1346 1347 if (*ptr == NULL_RTX) 1348 return 0; 1349 1350 switch (GET_CODE (*ptr)) 1351 { 1352 case ZERO_EXTRACT: 1353 case SIGN_EXTRACT: 1354 case STRICT_LOW_PART: 1355 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg) 1356 { 1357 param->retval = XEXP (*ptr, 0); 1358 return 1; 1359 } 1360 break; 1361 1362 case SUBREG: 1363 if (GET_CODE (SUBREG_REG (*ptr)) == REG 1364 && REGNO (SUBREG_REG (*ptr)) == reg) 1365 { 1366 param->retval = SUBREG_REG (*ptr); 1367 return 1; 1368 } 1369 break; 1370 1371 default: 1372 break; 1373 } 1374 1375 return 0; 1376} 1377 1378/* Process all immediate successors of the entry block looking for pseudo 1379 registers which are live on entry. Find all of those whose first 1380 instance is a partial register reference of some kind, and initialize 1381 them to 0 after the entry block. This will prevent bit sets within 1382 registers whose value is unknown, and may contain some kind of sticky 1383 bits we don't want. */ 1384 1385int 1386initialize_uninitialized_subregs (void) 1387{ 1388 rtx insn; 1389 edge e; 1390 int reg, did_something = 0; 1391 find_regno_partial_param param; 1392 1393 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) 1394 { 1395 basic_block bb = e->dest; 1396 regset map = bb->global_live_at_start; 1397 EXECUTE_IF_SET_IN_REG_SET (map, 1398 FIRST_PSEUDO_REGISTER, reg, 1399 { 1400 int uid = REGNO_FIRST_UID (reg); 1401 rtx i; 1402 1403 /* Find an insn which mentions the register we are looking for. 1404 Its preferable to have an instance of the register's rtl since 1405 there may be various flags set which we need to duplicate. 1406 If we can't find it, its probably an automatic whose initial 1407 value doesn't matter, or hopefully something we don't care about. */ 1408 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i)) 1409 ; 1410 if (i != NULL_RTX) 1411 { 1412 /* Found the insn, now get the REG rtx, if we can. */ 1413 param.regno_to_find = reg; 1414 for_each_rtx (&i, find_regno_partial, ¶m); 1415 if (param.retval != NULL_RTX) 1416 { 1417 start_sequence (); 1418 emit_move_insn (param.retval, 1419 CONST0_RTX (GET_MODE (param.retval))); 1420 insn = get_insns (); 1421 end_sequence (); 1422 insert_insn_on_edge (insn, e); 1423 did_something = 1; 1424 } 1425 } 1426 }); 1427 } 1428 1429 if (did_something) 1430 commit_edge_insertions (); 1431 return did_something; 1432} 1433 1434 1435/* Subroutines of life analysis. */ 1436 1437/* Allocate the permanent data structures that represent the results 1438 of life analysis. Not static since used also for stupid life analysis. */ 1439 1440void 1441allocate_bb_life_data (void) 1442{ 1443 basic_block bb; 1444 1445 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) 1446 { 1447 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1448 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1449 } 1450 1451 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack); 1452} 1453 1454void 1455allocate_reg_life_data (void) 1456{ 1457 int i; 1458 1459 max_regno = max_reg_num (); 1460 1461 /* Recalculate the register space, in case it has grown. Old style 1462 vector oriented regsets would set regset_{size,bytes} here also. */ 1463 allocate_reg_info (max_regno, FALSE, FALSE); 1464 1465 /* Reset all the data we'll collect in propagate_block and its 1466 subroutines. */ 1467 for (i = 0; i < max_regno; i++) 1468 { 1469 REG_N_SETS (i) = 0; 1470 REG_N_REFS (i) = 0; 1471 REG_N_DEATHS (i) = 0; 1472 REG_N_CALLS_CROSSED (i) = 0; 1473 REG_N_THROWING_CALLS_CROSSED (i) = 0; 1474 REG_LIVE_LENGTH (i) = 0; 1475 REG_FREQ (i) = 0; 1476 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN; 1477 } 1478} 1479 1480/* Delete dead instructions for propagate_block. */ 1481 1482static void 1483propagate_block_delete_insn (rtx insn) 1484{ 1485 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX); 1486 1487 /* If the insn referred to a label, and that label was attached to 1488 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's 1489 pretty much mandatory to delete it, because the ADDR_VEC may be 1490 referencing labels that no longer exist. 1491 1492 INSN may reference a deleted label, particularly when a jump 1493 table has been optimized into a direct jump. There's no 1494 real good way to fix up the reference to the deleted label 1495 when the label is deleted, so we just allow it here. */ 1496 1497 if (inote && GET_CODE (inote) == CODE_LABEL) 1498 { 1499 rtx label = XEXP (inote, 0); 1500 rtx next; 1501 1502 /* The label may be forced if it has been put in the constant 1503 pool. If that is the only use we must discard the table 1504 jump following it, but not the label itself. */ 1505 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label) 1506 && (next = next_nonnote_insn (label)) != NULL 1507 && GET_CODE (next) == JUMP_INSN 1508 && (GET_CODE (PATTERN (next)) == ADDR_VEC 1509 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)) 1510 { 1511 rtx pat = PATTERN (next); 1512 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC; 1513 int len = XVECLEN (pat, diff_vec_p); 1514 int i; 1515 1516 for (i = 0; i < len; i++) 1517 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--; 1518 1519 delete_insn_and_edges (next); 1520 ndead++; 1521 } 1522 } 1523 1524 delete_insn_and_edges (insn); 1525 ndead++; 1526} 1527 1528/* Delete dead libcalls for propagate_block. Return the insn 1529 before the libcall. */ 1530 1531static rtx 1532propagate_block_delete_libcall (rtx insn, rtx note) 1533{ 1534 rtx first = XEXP (note, 0); 1535 rtx before = PREV_INSN (first); 1536 1537 delete_insn_chain_and_edges (first, insn); 1538 ndead++; 1539 return before; 1540} 1541 1542/* Update the life-status of regs for one insn. Return the previous insn. */ 1543 1544rtx 1545propagate_one_insn (struct propagate_block_info *pbi, rtx insn) 1546{ 1547 rtx prev = PREV_INSN (insn); 1548 int flags = pbi->flags; 1549 int insn_is_dead = 0; 1550 int libcall_is_dead = 0; 1551 rtx note; 1552 int i; 1553 1554 if (! INSN_P (insn)) 1555 return prev; 1556 1557 note = find_reg_note (insn, REG_RETVAL, NULL_RTX); 1558 if (flags & PROP_SCAN_DEAD_CODE) 1559 { 1560 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn)); 1561 libcall_is_dead = (insn_is_dead && note != 0 1562 && libcall_dead_p (pbi, note, insn)); 1563 } 1564 1565 /* If an instruction consists of just dead store(s) on final pass, 1566 delete it. */ 1567 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead) 1568 { 1569 /* If we're trying to delete a prologue or epilogue instruction 1570 that isn't flagged as possibly being dead, something is wrong. 1571 But if we are keeping the stack pointer depressed, we might well 1572 be deleting insns that are used to compute the amount to update 1573 it by, so they are fine. */ 1574 if (reload_completed 1575 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE 1576 && (TYPE_RETURNS_STACK_DEPRESSED 1577 (TREE_TYPE (current_function_decl)))) 1578 && (((HAVE_epilogue || HAVE_prologue) 1579 && prologue_epilogue_contains (insn)) 1580 || (HAVE_sibcall_epilogue 1581 && sibcall_epilogue_contains (insn))) 1582 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0) 1583 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn); 1584 1585 /* Record sets. Do this even for dead instructions, since they 1586 would have killed the values if they hadn't been deleted. */ 1587 mark_set_regs (pbi, PATTERN (insn), insn); 1588 1589 /* CC0 is now known to be dead. Either this insn used it, 1590 in which case it doesn't anymore, or clobbered it, 1591 so the next insn can't use it. */ 1592 pbi->cc0_live = 0; 1593 1594 if (libcall_is_dead) 1595 prev = propagate_block_delete_libcall (insn, note); 1596 else 1597 { 1598 1599 /* If INSN contains a RETVAL note and is dead, but the libcall 1600 as a whole is not dead, then we want to remove INSN, but 1601 not the whole libcall sequence. 1602 1603 However, we need to also remove the dangling REG_LIBCALL 1604 note so that we do not have mis-matched LIBCALL/RETVAL 1605 notes. In theory we could find a new location for the 1606 REG_RETVAL note, but it hardly seems worth the effort. 1607 1608 NOTE at this point will be the RETVAL note if it exists. */ 1609 if (note) 1610 { 1611 rtx libcall_note; 1612 1613 libcall_note 1614 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX); 1615 remove_note (XEXP (note, 0), libcall_note); 1616 } 1617 1618 /* Similarly if INSN contains a LIBCALL note, remove the 1619 dangling REG_RETVAL note. */ 1620 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX); 1621 if (note) 1622 { 1623 rtx retval_note; 1624 1625 retval_note 1626 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX); 1627 remove_note (XEXP (note, 0), retval_note); 1628 } 1629 1630 /* Now delete INSN. */ 1631 propagate_block_delete_insn (insn); 1632 } 1633 1634 return prev; 1635 } 1636 1637 /* See if this is an increment or decrement that can be merged into 1638 a following memory address. */ 1639#ifdef AUTO_INC_DEC 1640 { 1641 rtx x = single_set (insn); 1642 1643 /* Does this instruction increment or decrement a register? */ 1644 if ((flags & PROP_AUTOINC) 1645 && x != 0 1646 && GET_CODE (SET_DEST (x)) == REG 1647 && (GET_CODE (SET_SRC (x)) == PLUS 1648 || GET_CODE (SET_SRC (x)) == MINUS) 1649 && XEXP (SET_SRC (x), 0) == SET_DEST (x) 1650 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT 1651 /* Ok, look for a following memory ref we can combine with. 1652 If one is found, change the memory ref to a PRE_INC 1653 or PRE_DEC, cancel this insn, and return 1. 1654 Return 0 if nothing has been done. */ 1655 && try_pre_increment_1 (pbi, insn)) 1656 return prev; 1657 } 1658#endif /* AUTO_INC_DEC */ 1659 1660 CLEAR_REG_SET (pbi->new_set); 1661 1662 /* If this is not the final pass, and this insn is copying the value of 1663 a library call and it's dead, don't scan the insns that perform the 1664 library call, so that the call's arguments are not marked live. */ 1665 if (libcall_is_dead) 1666 { 1667 /* Record the death of the dest reg. */ 1668 mark_set_regs (pbi, PATTERN (insn), insn); 1669 1670 insn = XEXP (note, 0); 1671 return PREV_INSN (insn); 1672 } 1673 else if (GET_CODE (PATTERN (insn)) == SET 1674 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx 1675 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS 1676 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx 1677 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT) 1678 /* We have an insn to pop a constant amount off the stack. 1679 (Such insns use PLUS regardless of the direction of the stack, 1680 and any insn to adjust the stack by a constant is always a pop.) 1681 These insns, if not dead stores, have no effect on life, though 1682 they do have an effect on the memory stores we are tracking. */ 1683 invalidate_mems_from_set (pbi, stack_pointer_rtx); 1684 else 1685 { 1686 rtx note; 1687 /* Any regs live at the time of a call instruction must not go 1688 in a register clobbered by calls. Find all regs now live and 1689 record this for them. */ 1690 1691 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO)) 1692 { 1693 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, 1694 { REG_N_CALLS_CROSSED (i)++; }); 1695 if (can_throw_internal (insn)) 1696 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, 1697 { REG_N_THROWING_CALLS_CROSSED (i)++; }); 1698 } 1699 1700 /* Record sets. Do this even for dead instructions, since they 1701 would have killed the values if they hadn't been deleted. */ 1702 mark_set_regs (pbi, PATTERN (insn), insn); 1703 1704 if (GET_CODE (insn) == CALL_INSN) 1705 { 1706 regset live_at_end; 1707 bool sibcall_p; 1708 rtx note, cond; 1709 int i; 1710 1711 cond = NULL_RTX; 1712 if (GET_CODE (PATTERN (insn)) == COND_EXEC) 1713 cond = COND_EXEC_TEST (PATTERN (insn)); 1714 1715 /* Non-constant calls clobber memory, constant calls do not 1716 clobber memory, though they may clobber outgoing arguments 1717 on the stack. */ 1718 if (! CONST_OR_PURE_CALL_P (insn)) 1719 { 1720 free_EXPR_LIST_list (&pbi->mem_set_list); 1721 pbi->mem_set_list_len = 0; 1722 } 1723 else 1724 invalidate_mems_from_set (pbi, stack_pointer_rtx); 1725 1726 /* There may be extra registers to be clobbered. */ 1727 for (note = CALL_INSN_FUNCTION_USAGE (insn); 1728 note; 1729 note = XEXP (note, 1)) 1730 if (GET_CODE (XEXP (note, 0)) == CLOBBER) 1731 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0), 1732 cond, insn, pbi->flags); 1733 1734 /* Calls change all call-used and global registers; sibcalls do not 1735 clobber anything that must be preserved at end-of-function, 1736 except for return values. */ 1737 1738 sibcall_p = SIBLING_CALL_P (insn); 1739 live_at_end = EXIT_BLOCK_PTR->global_live_at_start; 1740 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1741 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i) 1742 && ! (sibcall_p 1743 && REGNO_REG_SET_P (live_at_end, i) 1744 && ! refers_to_regno_p (i, i+1, 1745 current_function_return_rtx, 1746 (rtx *) 0))) 1747 { 1748 enum rtx_code code = global_regs[i] ? SET : CLOBBER; 1749 /* We do not want REG_UNUSED notes for these registers. */ 1750 mark_set_1 (pbi, code, regno_reg_rtx[i], cond, insn, 1751 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO)); 1752 } 1753 } 1754 1755 /* If an insn doesn't use CC0, it becomes dead since we assume 1756 that every insn clobbers it. So show it dead here; 1757 mark_used_regs will set it live if it is referenced. */ 1758 pbi->cc0_live = 0; 1759 1760 /* Record uses. */ 1761 if (! insn_is_dead) 1762 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn); 1763 if ((flags & PROP_EQUAL_NOTES) 1764 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX)) 1765 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)))) 1766 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn); 1767 1768 /* Sometimes we may have inserted something before INSN (such as a move) 1769 when we make an auto-inc. So ensure we will scan those insns. */ 1770#ifdef AUTO_INC_DEC 1771 prev = PREV_INSN (insn); 1772#endif 1773 1774 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN) 1775 { 1776 int i; 1777 rtx note, cond; 1778 1779 cond = NULL_RTX; 1780 if (GET_CODE (PATTERN (insn)) == COND_EXEC) 1781 cond = COND_EXEC_TEST (PATTERN (insn)); 1782 1783 /* Calls use their arguments, and may clobber memory which 1784 address involves some register. */ 1785 for (note = CALL_INSN_FUNCTION_USAGE (insn); 1786 note; 1787 note = XEXP (note, 1)) 1788 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both 1789 of which mark_used_regs knows how to handle. */ 1790 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn); 1791 1792 /* The stack ptr is used (honorarily) by a CALL insn. */ 1793 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM); 1794 1795 /* Calls may also reference any of the global registers, 1796 so they are made live. */ 1797 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1798 if (global_regs[i]) 1799 mark_used_reg (pbi, regno_reg_rtx[i], cond, insn); 1800 } 1801 } 1802 1803 /* On final pass, update counts of how many insns in which each reg 1804 is live. */ 1805 if (flags & PROP_REG_INFO) 1806 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, 1807 { REG_LIVE_LENGTH (i)++; }); 1808 1809 return prev; 1810} 1811 1812/* Initialize a propagate_block_info struct for public consumption. 1813 Note that the structure itself is opaque to this file, but that 1814 the user can use the regsets provided here. */ 1815 1816struct propagate_block_info * 1817init_propagate_block_info (basic_block bb, regset live, regset local_set, 1818 regset cond_local_set, int flags) 1819{ 1820 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi)); 1821 1822 pbi->bb = bb; 1823 pbi->reg_live = live; 1824 pbi->mem_set_list = NULL_RTX; 1825 pbi->mem_set_list_len = 0; 1826 pbi->local_set = local_set; 1827 pbi->cond_local_set = cond_local_set; 1828 pbi->cc0_live = 0; 1829 pbi->flags = flags; 1830 1831 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 1832 pbi->reg_next_use = xcalloc (max_reg_num (), sizeof (rtx)); 1833 else 1834 pbi->reg_next_use = NULL; 1835 1836 pbi->new_set = BITMAP_XMALLOC (); 1837 1838#ifdef HAVE_conditional_execution 1839 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL, 1840 free_reg_cond_life_info); 1841 pbi->reg_cond_reg = BITMAP_XMALLOC (); 1842 1843 /* If this block ends in a conditional branch, for each register 1844 live from one side of the branch and not the other, record the 1845 register as conditionally dead. */ 1846 if (GET_CODE (BB_END (bb)) == JUMP_INSN 1847 && any_condjump_p (BB_END (bb))) 1848 { 1849 regset_head diff_head; 1850 regset diff = INITIALIZE_REG_SET (diff_head); 1851 basic_block bb_true, bb_false; 1852 int i; 1853 1854 /* Identify the successor blocks. */ 1855 bb_true = bb->succ->dest; 1856 if (bb->succ->succ_next != NULL) 1857 { 1858 bb_false = bb->succ->succ_next->dest; 1859 1860 if (bb->succ->flags & EDGE_FALLTHRU) 1861 { 1862 basic_block t = bb_false; 1863 bb_false = bb_true; 1864 bb_true = t; 1865 } 1866 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU)) 1867 abort (); 1868 } 1869 else 1870 { 1871 /* This can happen with a conditional jump to the next insn. */ 1872 if (JUMP_LABEL (BB_END (bb)) != BB_HEAD (bb_true)) 1873 abort (); 1874 1875 /* Simplest way to do nothing. */ 1876 bb_false = bb_true; 1877 } 1878 1879 /* Compute which register lead different lives in the successors. */ 1880 if (bitmap_operation (diff, bb_true->global_live_at_start, 1881 bb_false->global_live_at_start, BITMAP_XOR)) 1882 { 1883 /* Extract the condition from the branch. */ 1884 rtx set_src = SET_SRC (pc_set (BB_END (bb))); 1885 rtx cond_true = XEXP (set_src, 0); 1886 rtx reg = XEXP (cond_true, 0); 1887 1888 if (GET_CODE (reg) == SUBREG) 1889 reg = SUBREG_REG (reg); 1890 1891 /* We can only track conditional lifetimes if the condition is 1892 in the form of a comparison of a register against zero. 1893 If the condition is more complex than that, then it is safe 1894 not to record any information. */ 1895 if (GET_CODE (reg) == REG 1896 && XEXP (cond_true, 1) == const0_rtx) 1897 { 1898 rtx cond_false 1899 = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)), 1900 GET_MODE (cond_true), XEXP (cond_true, 0), 1901 XEXP (cond_true, 1)); 1902 if (GET_CODE (XEXP (set_src, 1)) == PC) 1903 { 1904 rtx t = cond_false; 1905 cond_false = cond_true; 1906 cond_true = t; 1907 } 1908 1909 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg)); 1910 1911 /* For each such register, mark it conditionally dead. */ 1912 EXECUTE_IF_SET_IN_REG_SET 1913 (diff, 0, i, 1914 { 1915 struct reg_cond_life_info *rcli; 1916 rtx cond; 1917 1918 rcli = xmalloc (sizeof (*rcli)); 1919 1920 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i)) 1921 cond = cond_false; 1922 else 1923 cond = cond_true; 1924 rcli->condition = cond; 1925 rcli->stores = const0_rtx; 1926 rcli->orig_condition = cond; 1927 1928 splay_tree_insert (pbi->reg_cond_dead, i, 1929 (splay_tree_value) rcli); 1930 }); 1931 } 1932 } 1933 1934 FREE_REG_SET (diff); 1935 } 1936#endif 1937 1938 /* If this block has no successors, any stores to the frame that aren't 1939 used later in the block are dead. So make a pass over the block 1940 recording any such that are made and show them dead at the end. We do 1941 a very conservative and simple job here. */ 1942 if (optimize 1943 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE 1944 && (TYPE_RETURNS_STACK_DEPRESSED 1945 (TREE_TYPE (current_function_decl)))) 1946 && (flags & PROP_SCAN_DEAD_STORES) 1947 && (bb->succ == NULL 1948 || (bb->succ->succ_next == NULL 1949 && bb->succ->dest == EXIT_BLOCK_PTR 1950 && ! current_function_calls_eh_return))) 1951 { 1952 rtx insn, set; 1953 for (insn = BB_END (bb); insn != BB_HEAD (bb); insn = PREV_INSN (insn)) 1954 if (GET_CODE (insn) == INSN 1955 && (set = single_set (insn)) 1956 && GET_CODE (SET_DEST (set)) == MEM) 1957 { 1958 rtx mem = SET_DEST (set); 1959 rtx canon_mem = canon_rtx (mem); 1960 1961 if (XEXP (canon_mem, 0) == frame_pointer_rtx 1962 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS 1963 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx 1964 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT)) 1965 add_to_mem_set_list (pbi, canon_mem); 1966 } 1967 } 1968 1969 return pbi; 1970} 1971 1972/* Release a propagate_block_info struct. */ 1973 1974void 1975free_propagate_block_info (struct propagate_block_info *pbi) 1976{ 1977 free_EXPR_LIST_list (&pbi->mem_set_list); 1978 1979 BITMAP_XFREE (pbi->new_set); 1980 1981#ifdef HAVE_conditional_execution 1982 splay_tree_delete (pbi->reg_cond_dead); 1983 BITMAP_XFREE (pbi->reg_cond_reg); 1984#endif 1985 1986 if (pbi->reg_next_use) 1987 free (pbi->reg_next_use); 1988 1989 free (pbi); 1990} 1991 1992/* Compute the registers live at the beginning of a basic block BB from 1993 those live at the end. 1994 1995 When called, REG_LIVE contains those live at the end. On return, it 1996 contains those live at the beginning. 1997 1998 LOCAL_SET, if non-null, will be set with all registers killed 1999 unconditionally by this basic block. 2000 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers 2001 killed conditionally by this basic block. If there is any unconditional 2002 set of a register, then the corresponding bit will be set in LOCAL_SET 2003 and cleared in COND_LOCAL_SET. 2004 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this 2005 case, the resulting set will be equal to the union of the two sets that 2006 would otherwise be computed. 2007 2008 Return nonzero if an INSN is deleted (i.e. by dead code removal). */ 2009 2010int 2011propagate_block (basic_block bb, regset live, regset local_set, 2012 regset cond_local_set, int flags) 2013{ 2014 struct propagate_block_info *pbi; 2015 rtx insn, prev; 2016 int changed; 2017 2018 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags); 2019 2020 if (flags & PROP_REG_INFO) 2021 { 2022 int i; 2023 2024 /* Process the regs live at the end of the block. 2025 Mark them as not local to any one basic block. */ 2026 EXECUTE_IF_SET_IN_REG_SET (live, 0, i, 2027 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; }); 2028 } 2029 2030 /* Scan the block an insn at a time from end to beginning. */ 2031 2032 changed = 0; 2033 for (insn = BB_END (bb); ; insn = prev) 2034 { 2035 /* If this is a call to `setjmp' et al, warn if any 2036 non-volatile datum is live. */ 2037 if ((flags & PROP_REG_INFO) 2038 && GET_CODE (insn) == CALL_INSN 2039 && find_reg_note (insn, REG_SETJMP, NULL)) 2040 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live); 2041 2042 prev = propagate_one_insn (pbi, insn); 2043 if (!prev) 2044 changed |= insn != get_insns (); 2045 else 2046 changed |= NEXT_INSN (prev) != insn; 2047 2048 if (insn == BB_HEAD (bb)) 2049 break; 2050 } 2051 2052 free_propagate_block_info (pbi); 2053 2054 return changed; 2055} 2056 2057/* Return 1 if X (the body of an insn, or part of it) is just dead stores 2058 (SET expressions whose destinations are registers dead after the insn). 2059 NEEDED is the regset that says which regs are alive after the insn. 2060 2061 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL. 2062 2063 If X is the entire body of an insn, NOTES contains the reg notes 2064 pertaining to the insn. */ 2065 2066static int 2067insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok, 2068 rtx notes ATTRIBUTE_UNUSED) 2069{ 2070 enum rtx_code code = GET_CODE (x); 2071 2072 /* Don't eliminate insns that may trap. */ 2073 if (flag_non_call_exceptions && may_trap_p (x)) 2074 return 0; 2075 2076#ifdef AUTO_INC_DEC 2077 /* As flow is invoked after combine, we must take existing AUTO_INC 2078 expressions into account. */ 2079 for (; notes; notes = XEXP (notes, 1)) 2080 { 2081 if (REG_NOTE_KIND (notes) == REG_INC) 2082 { 2083 int regno = REGNO (XEXP (notes, 0)); 2084 2085 /* Don't delete insns to set global regs. */ 2086 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) 2087 || REGNO_REG_SET_P (pbi->reg_live, regno)) 2088 return 0; 2089 } 2090 } 2091#endif 2092 2093 /* If setting something that's a reg or part of one, 2094 see if that register's altered value will be live. */ 2095 2096 if (code == SET) 2097 { 2098 rtx r = SET_DEST (x); 2099 2100#ifdef HAVE_cc0 2101 if (GET_CODE (r) == CC0) 2102 return ! pbi->cc0_live; 2103#endif 2104 2105 /* A SET that is a subroutine call cannot be dead. */ 2106 if (GET_CODE (SET_SRC (x)) == CALL) 2107 { 2108 if (! call_ok) 2109 return 0; 2110 } 2111 2112 /* Don't eliminate loads from volatile memory or volatile asms. */ 2113 else if (volatile_refs_p (SET_SRC (x))) 2114 return 0; 2115 2116 if (GET_CODE (r) == MEM) 2117 { 2118 rtx temp, canon_r; 2119 2120 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode) 2121 return 0; 2122 2123 canon_r = canon_rtx (r); 2124 2125 /* Walk the set of memory locations we are currently tracking 2126 and see if one is an identical match to this memory location. 2127 If so, this memory write is dead (remember, we're walking 2128 backwards from the end of the block to the start). Since 2129 rtx_equal_p does not check the alias set or flags, we also 2130 must have the potential for them to conflict (anti_dependence). */ 2131 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1)) 2132 if (unchanging_anti_dependence (r, XEXP (temp, 0))) 2133 { 2134 rtx mem = XEXP (temp, 0); 2135 2136 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0)) 2137 && (GET_MODE_SIZE (GET_MODE (canon_r)) 2138 <= GET_MODE_SIZE (GET_MODE (mem)))) 2139 return 1; 2140 2141#ifdef AUTO_INC_DEC 2142 /* Check if memory reference matches an auto increment. Only 2143 post increment/decrement or modify are valid. */ 2144 if (GET_MODE (mem) == GET_MODE (r) 2145 && (GET_CODE (XEXP (mem, 0)) == POST_DEC 2146 || GET_CODE (XEXP (mem, 0)) == POST_INC 2147 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY) 2148 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r) 2149 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0))) 2150 return 1; 2151#endif 2152 } 2153 } 2154 else 2155 { 2156 while (GET_CODE (r) == SUBREG 2157 || GET_CODE (r) == STRICT_LOW_PART 2158 || GET_CODE (r) == ZERO_EXTRACT) 2159 r = XEXP (r, 0); 2160 2161 if (GET_CODE (r) == REG) 2162 { 2163 int regno = REGNO (r); 2164 2165 /* Obvious. */ 2166 if (REGNO_REG_SET_P (pbi->reg_live, regno)) 2167 return 0; 2168 2169 /* If this is a hard register, verify that subsequent 2170 words are not needed. */ 2171 if (regno < FIRST_PSEUDO_REGISTER) 2172 { 2173 int n = HARD_REGNO_NREGS (regno, GET_MODE (r)); 2174 2175 while (--n > 0) 2176 if (REGNO_REG_SET_P (pbi->reg_live, regno+n)) 2177 return 0; 2178 } 2179 2180 /* Don't delete insns to set global regs. */ 2181 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) 2182 return 0; 2183 2184 /* Make sure insns to set the stack pointer aren't deleted. */ 2185 if (regno == STACK_POINTER_REGNUM) 2186 return 0; 2187 2188 /* ??? These bits might be redundant with the force live bits 2189 in calculate_global_regs_live. We would delete from 2190 sequential sets; whether this actually affects real code 2191 for anything but the stack pointer I don't know. */ 2192 /* Make sure insns to set the frame pointer aren't deleted. */ 2193 if (regno == FRAME_POINTER_REGNUM 2194 && (! reload_completed || frame_pointer_needed)) 2195 return 0; 2196#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 2197 if (regno == HARD_FRAME_POINTER_REGNUM 2198 && (! reload_completed || frame_pointer_needed)) 2199 return 0; 2200#endif 2201 2202#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 2203 /* Make sure insns to set arg pointer are never deleted 2204 (if the arg pointer isn't fixed, there will be a USE 2205 for it, so we can treat it normally). */ 2206 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) 2207 return 0; 2208#endif 2209 2210 /* Otherwise, the set is dead. */ 2211 return 1; 2212 } 2213 } 2214 } 2215 2216 /* If performing several activities, insn is dead if each activity 2217 is individually dead. Also, CLOBBERs and USEs can be ignored; a 2218 CLOBBER or USE that's inside a PARALLEL doesn't make the insn 2219 worth keeping. */ 2220 else if (code == PARALLEL) 2221 { 2222 int i = XVECLEN (x, 0); 2223 2224 for (i--; i >= 0; i--) 2225 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER 2226 && GET_CODE (XVECEXP (x, 0, i)) != USE 2227 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX)) 2228 return 0; 2229 2230 return 1; 2231 } 2232 2233 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That 2234 is not necessarily true for hard registers until after reload. */ 2235 else if (code == CLOBBER) 2236 { 2237 if (GET_CODE (XEXP (x, 0)) == REG 2238 && (REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER 2239 || reload_completed) 2240 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0)))) 2241 return 1; 2242 } 2243 2244 /* ??? A base USE is a historical relic. It ought not be needed anymore. 2245 Instances where it is still used are either (1) temporary and the USE 2246 escaped the pass, (2) cruft and the USE need not be emitted anymore, 2247 or (3) hiding bugs elsewhere that are not properly representing data 2248 flow. */ 2249 2250 return 0; 2251} 2252 2253/* If INSN is the last insn in a libcall, and assuming INSN is dead, 2254 return 1 if the entire library call is dead. 2255 This is true if INSN copies a register (hard or pseudo) 2256 and if the hard return reg of the call insn is dead. 2257 (The caller should have tested the destination of the SET inside 2258 INSN already for death.) 2259 2260 If this insn doesn't just copy a register, then we don't 2261 have an ordinary libcall. In that case, cse could not have 2262 managed to substitute the source for the dest later on, 2263 so we can assume the libcall is dead. 2264 2265 PBI is the block info giving pseudoregs live before this insn. 2266 NOTE is the REG_RETVAL note of the insn. */ 2267 2268static int 2269libcall_dead_p (struct propagate_block_info *pbi, rtx note, rtx insn) 2270{ 2271 rtx x = single_set (insn); 2272 2273 if (x) 2274 { 2275 rtx r = SET_SRC (x); 2276 2277 if (GET_CODE (r) == REG || GET_CODE (r) == SUBREG) 2278 { 2279 rtx call = XEXP (note, 0); 2280 rtx call_pat; 2281 int i; 2282 2283 /* Find the call insn. */ 2284 while (call != insn && GET_CODE (call) != CALL_INSN) 2285 call = NEXT_INSN (call); 2286 2287 /* If there is none, do nothing special, 2288 since ordinary death handling can understand these insns. */ 2289 if (call == insn) 2290 return 0; 2291 2292 /* See if the hard reg holding the value is dead. 2293 If this is a PARALLEL, find the call within it. */ 2294 call_pat = PATTERN (call); 2295 if (GET_CODE (call_pat) == PARALLEL) 2296 { 2297 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--) 2298 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET 2299 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL) 2300 break; 2301 2302 /* This may be a library call that is returning a value 2303 via invisible pointer. Do nothing special, since 2304 ordinary death handling can understand these insns. */ 2305 if (i < 0) 2306 return 0; 2307 2308 call_pat = XVECEXP (call_pat, 0, i); 2309 } 2310 2311 if (! insn_dead_p (pbi, call_pat, 1, REG_NOTES (call))) 2312 return 0; 2313 2314 while ((insn = PREV_INSN (insn)) != call) 2315 { 2316 if (! INSN_P (insn)) 2317 continue; 2318 if (! insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn))) 2319 return 0; 2320 } 2321 return 1; 2322 } 2323 } 2324 return 0; 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 (unsigned int regno) 2334{ 2335 if (n_basic_blocks == 0 2336 || (regno < FIRST_PSEUDO_REGISTER 2337 && (global_regs[regno] 2338 || fixed_regs[regno] 2339 || FUNCTION_ARG_REGNO_P (regno)))) 2340 return 0; 2341 2342 return REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno); 2343} 2344 2345/* 1 if register REGNO was alive at a place where `setjmp' was called 2346 and was set more than once or is an argument. 2347 Such regs may be clobbered by `longjmp'. */ 2348 2349int 2350regno_clobbered_at_setjmp (int regno) 2351{ 2352 if (n_basic_blocks == 0) 2353 return 0; 2354 2355 return ((REG_N_SETS (regno) > 1 2356 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno)) 2357 && REGNO_REG_SET_P (regs_live_at_setjmp, regno)); 2358} 2359 2360/* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the 2361 maximal list size; look for overlaps in mode and select the largest. */ 2362static void 2363add_to_mem_set_list (struct propagate_block_info *pbi, rtx mem) 2364{ 2365 rtx i; 2366 2367 /* We don't know how large a BLKmode store is, so we must not 2368 take them into consideration. */ 2369 if (GET_MODE (mem) == BLKmode) 2370 return; 2371 2372 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1)) 2373 { 2374 rtx e = XEXP (i, 0); 2375 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0))) 2376 { 2377 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e))) 2378 { 2379#ifdef AUTO_INC_DEC 2380 /* If we must store a copy of the mem, we can just modify 2381 the mode of the stored copy. */ 2382 if (pbi->flags & PROP_AUTOINC) 2383 PUT_MODE (e, GET_MODE (mem)); 2384 else 2385#endif 2386 XEXP (i, 0) = mem; 2387 } 2388 return; 2389 } 2390 } 2391 2392 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN) 2393 { 2394#ifdef AUTO_INC_DEC 2395 /* Store a copy of mem, otherwise the address may be 2396 scrogged by find_auto_inc. */ 2397 if (pbi->flags & PROP_AUTOINC) 2398 mem = shallow_copy_rtx (mem); 2399#endif 2400 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list); 2401 pbi->mem_set_list_len++; 2402 } 2403} 2404 2405/* INSN references memory, possibly using autoincrement addressing modes. 2406 Find any entries on the mem_set_list that need to be invalidated due 2407 to an address change. */ 2408 2409static int 2410invalidate_mems_from_autoinc (rtx *px, void *data) 2411{ 2412 rtx x = *px; 2413 struct propagate_block_info *pbi = data; 2414 2415 if (GET_RTX_CLASS (GET_CODE (x)) == 'a') 2416 { 2417 invalidate_mems_from_set (pbi, XEXP (x, 0)); 2418 return -1; 2419 } 2420 2421 return 0; 2422} 2423 2424/* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */ 2425 2426static void 2427invalidate_mems_from_set (struct propagate_block_info *pbi, rtx exp) 2428{ 2429 rtx temp = pbi->mem_set_list; 2430 rtx prev = NULL_RTX; 2431 rtx next; 2432 2433 while (temp) 2434 { 2435 next = XEXP (temp, 1); 2436 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0))) 2437 { 2438 /* Splice this entry out of the list. */ 2439 if (prev) 2440 XEXP (prev, 1) = next; 2441 else 2442 pbi->mem_set_list = next; 2443 free_EXPR_LIST_node (temp); 2444 pbi->mem_set_list_len--; 2445 } 2446 else 2447 prev = temp; 2448 temp = next; 2449 } 2450} 2451 2452/* Process the registers that are set within X. Their bits are set to 2453 1 in the regset DEAD, because they are dead prior to this insn. 2454 2455 If INSN is nonzero, it is the insn being processed. 2456 2457 FLAGS is the set of operations to perform. */ 2458 2459static void 2460mark_set_regs (struct propagate_block_info *pbi, rtx x, rtx insn) 2461{ 2462 rtx cond = NULL_RTX; 2463 rtx link; 2464 enum rtx_code code; 2465 int flags = pbi->flags; 2466 2467 if (insn) 2468 for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) 2469 { 2470 if (REG_NOTE_KIND (link) == REG_INC) 2471 mark_set_1 (pbi, SET, XEXP (link, 0), 2472 (GET_CODE (x) == COND_EXEC 2473 ? COND_EXEC_TEST (x) : NULL_RTX), 2474 insn, flags); 2475 } 2476 retry: 2477 switch (code = GET_CODE (x)) 2478 { 2479 case SET: 2480 if (GET_CODE (XEXP (x, 1)) == ASM_OPERANDS) 2481 flags |= PROP_ASM_SCAN; 2482 /* Fall through */ 2483 case CLOBBER: 2484 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, 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 /* We must scan forwards. If we have an asm, we need to set 2497 the PROP_ASM_SCAN flag before scanning the clobbers. */ 2498 for (i = 0; i < XVECLEN (x, 0); i++) 2499 { 2500 rtx sub = XVECEXP (x, 0, i); 2501 switch (code = GET_CODE (sub)) 2502 { 2503 case COND_EXEC: 2504 if (cond != NULL_RTX) 2505 abort (); 2506 2507 cond = COND_EXEC_TEST (sub); 2508 sub = COND_EXEC_CODE (sub); 2509 if (GET_CODE (sub) == SET) 2510 goto mark_set; 2511 if (GET_CODE (sub) == CLOBBER) 2512 goto mark_clob; 2513 break; 2514 2515 case SET: 2516 mark_set: 2517 if (GET_CODE (XEXP (sub, 1)) == ASM_OPERANDS) 2518 flags |= PROP_ASM_SCAN; 2519 /* Fall through */ 2520 case CLOBBER: 2521 mark_clob: 2522 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, flags); 2523 break; 2524 2525 case ASM_OPERANDS: 2526 flags |= PROP_ASM_SCAN; 2527 break; 2528 2529 default: 2530 break; 2531 } 2532 } 2533 break; 2534 } 2535 2536 default: 2537 break; 2538 } 2539} 2540 2541/* Process a single set, which appears in INSN. REG (which may not 2542 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is 2543 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC). 2544 If the set is conditional (because it appear in a COND_EXEC), COND 2545 will be the condition. */ 2546 2547static void 2548mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx cond, rtx insn, int flags) 2549{ 2550 int regno_first = -1, regno_last = -1; 2551 unsigned long not_dead = 0; 2552 int i; 2553 2554 /* Modifying just one hardware register of a multi-reg value or just a 2555 byte field of a register does not mean the value from before this insn 2556 is now dead. Of course, if it was dead after it's unused now. */ 2557 2558 switch (GET_CODE (reg)) 2559 { 2560 case PARALLEL: 2561 /* Some targets place small structures in registers for return values of 2562 functions. We have to detect this case specially here to get correct 2563 flow information. */ 2564 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--) 2565 if (XEXP (XVECEXP (reg, 0, i), 0) != 0) 2566 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn, 2567 flags); 2568 return; 2569 2570 case ZERO_EXTRACT: 2571 case SIGN_EXTRACT: 2572 case STRICT_LOW_PART: 2573 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */ 2574 do 2575 reg = XEXP (reg, 0); 2576 while (GET_CODE (reg) == SUBREG 2577 || GET_CODE (reg) == ZERO_EXTRACT 2578 || GET_CODE (reg) == SIGN_EXTRACT 2579 || GET_CODE (reg) == STRICT_LOW_PART); 2580 if (GET_CODE (reg) == MEM) 2581 break; 2582 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg)); 2583 /* Fall through. */ 2584 2585 case REG: 2586 regno_last = regno_first = REGNO (reg); 2587 if (regno_first < FIRST_PSEUDO_REGISTER) 2588 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1; 2589 break; 2590 2591 case SUBREG: 2592 if (GET_CODE (SUBREG_REG (reg)) == REG) 2593 { 2594 enum machine_mode outer_mode = GET_MODE (reg); 2595 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg)); 2596 2597 /* Identify the range of registers affected. This is moderately 2598 tricky for hard registers. See alter_subreg. */ 2599 2600 regno_last = regno_first = REGNO (SUBREG_REG (reg)); 2601 if (regno_first < FIRST_PSEUDO_REGISTER) 2602 { 2603 regno_first += subreg_regno_offset (regno_first, inner_mode, 2604 SUBREG_BYTE (reg), 2605 outer_mode); 2606 regno_last = (regno_first 2607 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1); 2608 2609 /* Since we've just adjusted the register number ranges, make 2610 sure REG matches. Otherwise some_was_live will be clear 2611 when it shouldn't have been, and we'll create incorrect 2612 REG_UNUSED notes. */ 2613 reg = gen_rtx_REG (outer_mode, regno_first); 2614 } 2615 else 2616 { 2617 /* If the number of words in the subreg is less than the number 2618 of words in the full register, we have a well-defined partial 2619 set. Otherwise the high bits are undefined. 2620 2621 This is only really applicable to pseudos, since we just took 2622 care of multi-word hard registers. */ 2623 if (((GET_MODE_SIZE (outer_mode) 2624 + UNITS_PER_WORD - 1) / UNITS_PER_WORD) 2625 < ((GET_MODE_SIZE (inner_mode) 2626 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)) 2627 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, 2628 regno_first); 2629 2630 reg = SUBREG_REG (reg); 2631 } 2632 } 2633 else 2634 reg = SUBREG_REG (reg); 2635 break; 2636 2637 default: 2638 break; 2639 } 2640 2641 /* If this set is a MEM, then it kills any aliased writes. 2642 If this set is a REG, then it kills any MEMs which use the reg. */ 2643 if (optimize && (flags & PROP_SCAN_DEAD_STORES)) 2644 { 2645 if (GET_CODE (reg) == REG) 2646 invalidate_mems_from_set (pbi, reg); 2647 2648 /* If the memory reference had embedded side effects (autoincrement 2649 address modes. Then we may need to kill some entries on the 2650 memory set list. */ 2651 if (insn && GET_CODE (reg) == MEM) 2652 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi); 2653 2654 if (GET_CODE (reg) == MEM && ! side_effects_p (reg) 2655 /* ??? With more effort we could track conditional memory life. */ 2656 && ! cond) 2657 add_to_mem_set_list (pbi, canon_rtx (reg)); 2658 } 2659 2660 if (GET_CODE (reg) == REG 2661 && ! (regno_first == FRAME_POINTER_REGNUM 2662 && (! reload_completed || frame_pointer_needed)) 2663#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 2664 && ! (regno_first == HARD_FRAME_POINTER_REGNUM 2665 && (! reload_completed || frame_pointer_needed)) 2666#endif 2667#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 2668 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first]) 2669#endif 2670 ) 2671 { 2672 int some_was_live = 0, some_was_dead = 0; 2673 2674 for (i = regno_first; i <= regno_last; ++i) 2675 { 2676 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i); 2677 if (pbi->local_set) 2678 { 2679 /* Order of the set operation matters here since both 2680 sets may be the same. */ 2681 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i); 2682 if (cond != NULL_RTX 2683 && ! REGNO_REG_SET_P (pbi->local_set, i)) 2684 SET_REGNO_REG_SET (pbi->cond_local_set, i); 2685 else 2686 SET_REGNO_REG_SET (pbi->local_set, i); 2687 } 2688 if (code != CLOBBER) 2689 SET_REGNO_REG_SET (pbi->new_set, i); 2690 2691 some_was_live |= needed_regno; 2692 some_was_dead |= ! needed_regno; 2693 } 2694 2695#ifdef HAVE_conditional_execution 2696 /* Consider conditional death in deciding that the register needs 2697 a death note. */ 2698 if (some_was_live && ! not_dead 2699 /* The stack pointer is never dead. Well, not strictly true, 2700 but it's very difficult to tell from here. Hopefully 2701 combine_stack_adjustments will fix up the most egregious 2702 errors. */ 2703 && regno_first != STACK_POINTER_REGNUM) 2704 { 2705 for (i = regno_first; i <= regno_last; ++i) 2706 if (! mark_regno_cond_dead (pbi, i, cond)) 2707 not_dead |= ((unsigned long) 1) << (i - regno_first); 2708 } 2709#endif 2710 2711 /* Additional data to record if this is the final pass. */ 2712 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO 2713 | PROP_DEATH_NOTES | PROP_AUTOINC)) 2714 { 2715 rtx y; 2716 int blocknum = pbi->bb->index; 2717 2718 y = NULL_RTX; 2719 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 2720 { 2721 y = pbi->reg_next_use[regno_first]; 2722 2723 /* The next use is no longer next, since a store intervenes. */ 2724 for (i = regno_first; i <= regno_last; ++i) 2725 pbi->reg_next_use[i] = 0; 2726 } 2727 2728 if (flags & PROP_REG_INFO) 2729 { 2730 for (i = regno_first; i <= regno_last; ++i) 2731 { 2732 /* Count (weighted) references, stores, etc. This counts a 2733 register twice if it is modified, but that is correct. */ 2734 REG_N_SETS (i) += 1; 2735 REG_N_REFS (i) += 1; 2736 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb); 2737 2738 /* The insns where a reg is live are normally counted 2739 elsewhere, but we want the count to include the insn 2740 where the reg is set, and the normal counting mechanism 2741 would not count it. */ 2742 REG_LIVE_LENGTH (i) += 1; 2743 } 2744 2745 /* If this is a hard reg, record this function uses the reg. */ 2746 if (regno_first < FIRST_PSEUDO_REGISTER) 2747 { 2748 for (i = regno_first; i <= regno_last; i++) 2749 regs_ever_live[i] = 1; 2750 if (flags & PROP_ASM_SCAN) 2751 for (i = regno_first; i <= regno_last; i++) 2752 regs_asm_clobbered[i] = 1; 2753 } 2754 else 2755 { 2756 /* Keep track of which basic blocks each reg appears in. */ 2757 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN) 2758 REG_BASIC_BLOCK (regno_first) = blocknum; 2759 else if (REG_BASIC_BLOCK (regno_first) != blocknum) 2760 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL; 2761 } 2762 } 2763 2764 if (! some_was_dead) 2765 { 2766 if (flags & PROP_LOG_LINKS) 2767 { 2768 /* Make a logical link from the next following insn 2769 that uses this register, back to this insn. 2770 The following insns have already been processed. 2771 2772 We don't build a LOG_LINK for hard registers containing 2773 in ASM_OPERANDs. If these registers get replaced, 2774 we might wind up changing the semantics of the insn, 2775 even if reload can make what appear to be valid 2776 assignments later. 2777 2778 We don't build a LOG_LINK for global registers to 2779 or from a function call. We don't want to let 2780 combine think that it knows what is going on with 2781 global registers. */ 2782 if (y && (BLOCK_NUM (y) == blocknum) 2783 && (regno_first >= FIRST_PSEUDO_REGISTER 2784 || (asm_noperands (PATTERN (y)) < 0 2785 && ! ((GET_CODE (insn) == CALL_INSN 2786 || GET_CODE (y) == CALL_INSN) 2787 && global_regs[regno_first])))) 2788 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y)); 2789 } 2790 } 2791 else if (not_dead) 2792 ; 2793 else if (! some_was_live) 2794 { 2795 if (flags & PROP_REG_INFO) 2796 REG_N_DEATHS (regno_first) += 1; 2797 2798 if (flags & PROP_DEATH_NOTES) 2799 { 2800 /* Note that dead stores have already been deleted 2801 when possible. If we get here, we have found a 2802 dead store that cannot be eliminated (because the 2803 same insn does something useful). Indicate this 2804 by marking the reg being set as dying here. */ 2805 REG_NOTES (insn) 2806 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn)); 2807 } 2808 } 2809 else 2810 { 2811 if (flags & PROP_DEATH_NOTES) 2812 { 2813 /* This is a case where we have a multi-word hard register 2814 and some, but not all, of the words of the register are 2815 needed in subsequent insns. Write REG_UNUSED notes 2816 for those parts that were not needed. This case should 2817 be rare. */ 2818 2819 for (i = regno_first; i <= regno_last; ++i) 2820 if (! REGNO_REG_SET_P (pbi->reg_live, i)) 2821 REG_NOTES (insn) 2822 = alloc_EXPR_LIST (REG_UNUSED, 2823 regno_reg_rtx[i], 2824 REG_NOTES (insn)); 2825 } 2826 } 2827 } 2828 2829 /* Mark the register as being dead. */ 2830 if (some_was_live 2831 /* The stack pointer is never dead. Well, not strictly true, 2832 but it's very difficult to tell from here. Hopefully 2833 combine_stack_adjustments will fix up the most egregious 2834 errors. */ 2835 && regno_first != STACK_POINTER_REGNUM) 2836 { 2837 for (i = regno_first; i <= regno_last; ++i) 2838 if (!(not_dead & (((unsigned long) 1) << (i - regno_first)))) 2839 CLEAR_REGNO_REG_SET (pbi->reg_live, i); 2840 } 2841 } 2842 else if (GET_CODE (reg) == REG) 2843 { 2844 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 2845 pbi->reg_next_use[regno_first] = 0; 2846 2847 if ((flags & PROP_REG_INFO) != 0 2848 && (flags & PROP_ASM_SCAN) != 0 2849 && regno_first < FIRST_PSEUDO_REGISTER) 2850 { 2851 for (i = regno_first; i <= regno_last; i++) 2852 regs_asm_clobbered[i] = 1; 2853 } 2854 } 2855 2856 /* If this is the last pass and this is a SCRATCH, show it will be dying 2857 here and count it. */ 2858 else if (GET_CODE (reg) == SCRATCH) 2859 { 2860 if (flags & PROP_DEATH_NOTES) 2861 REG_NOTES (insn) 2862 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn)); 2863 } 2864} 2865 2866#ifdef HAVE_conditional_execution 2867/* Mark REGNO conditionally dead. 2868 Return true if the register is now unconditionally dead. */ 2869 2870static int 2871mark_regno_cond_dead (struct propagate_block_info *pbi, int regno, rtx cond) 2872{ 2873 /* If this is a store to a predicate register, the value of the 2874 predicate is changing, we don't know that the predicate as seen 2875 before is the same as that seen after. Flush all dependent 2876 conditions from reg_cond_dead. This will make all such 2877 conditionally live registers unconditionally live. */ 2878 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno)) 2879 flush_reg_cond_reg (pbi, regno); 2880 2881 /* If this is an unconditional store, remove any conditional 2882 life that may have existed. */ 2883 if (cond == NULL_RTX) 2884 splay_tree_remove (pbi->reg_cond_dead, regno); 2885 else 2886 { 2887 splay_tree_node node; 2888 struct reg_cond_life_info *rcli; 2889 rtx ncond; 2890 2891 /* Otherwise this is a conditional set. Record that fact. 2892 It may have been conditionally used, or there may be a 2893 subsequent set with a complimentary condition. */ 2894 2895 node = splay_tree_lookup (pbi->reg_cond_dead, regno); 2896 if (node == NULL) 2897 { 2898 /* The register was unconditionally live previously. 2899 Record the current condition as the condition under 2900 which it is dead. */ 2901 rcli = xmalloc (sizeof (*rcli)); 2902 rcli->condition = cond; 2903 rcli->stores = cond; 2904 rcli->orig_condition = const0_rtx; 2905 splay_tree_insert (pbi->reg_cond_dead, regno, 2906 (splay_tree_value) rcli); 2907 2908 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); 2909 2910 /* Not unconditionally dead. */ 2911 return 0; 2912 } 2913 else 2914 { 2915 /* The register was conditionally live previously. 2916 Add the new condition to the old. */ 2917 rcli = (struct reg_cond_life_info *) node->value; 2918 ncond = rcli->condition; 2919 ncond = ior_reg_cond (ncond, cond, 1); 2920 if (rcli->stores == const0_rtx) 2921 rcli->stores = cond; 2922 else if (rcli->stores != const1_rtx) 2923 rcli->stores = ior_reg_cond (rcli->stores, cond, 1); 2924 2925 /* If the register is now unconditionally dead, remove the entry 2926 in the splay_tree. A register is unconditionally dead if the 2927 dead condition ncond is true. A register is also unconditionally 2928 dead if the sum of all conditional stores is an unconditional 2929 store (stores is true), and the dead condition is identically the 2930 same as the original dead condition initialized at the end of 2931 the block. This is a pointer compare, not an rtx_equal_p 2932 compare. */ 2933 if (ncond == const1_rtx 2934 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx)) 2935 splay_tree_remove (pbi->reg_cond_dead, regno); 2936 else 2937 { 2938 rcli->condition = ncond; 2939 2940 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); 2941 2942 /* Not unconditionally dead. */ 2943 return 0; 2944 } 2945 } 2946 } 2947 2948 return 1; 2949} 2950 2951/* Called from splay_tree_delete for pbi->reg_cond_life. */ 2952 2953static void 2954free_reg_cond_life_info (splay_tree_value value) 2955{ 2956 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value; 2957 free (rcli); 2958} 2959 2960/* Helper function for flush_reg_cond_reg. */ 2961 2962static int 2963flush_reg_cond_reg_1 (splay_tree_node node, void *data) 2964{ 2965 struct reg_cond_life_info *rcli; 2966 int *xdata = (int *) data; 2967 unsigned int regno = xdata[0]; 2968 2969 /* Don't need to search if last flushed value was farther on in 2970 the in-order traversal. */ 2971 if (xdata[1] >= (int) node->key) 2972 return 0; 2973 2974 /* Splice out portions of the expression that refer to regno. */ 2975 rcli = (struct reg_cond_life_info *) node->value; 2976 rcli->condition = elim_reg_cond (rcli->condition, regno); 2977 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx) 2978 rcli->stores = elim_reg_cond (rcli->stores, regno); 2979 2980 /* If the entire condition is now false, signal the node to be removed. */ 2981 if (rcli->condition == const0_rtx) 2982 { 2983 xdata[1] = node->key; 2984 return -1; 2985 } 2986 else if (rcli->condition == const1_rtx) 2987 abort (); 2988 2989 return 0; 2990} 2991 2992/* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */ 2993 2994static void 2995flush_reg_cond_reg (struct propagate_block_info *pbi, int regno) 2996{ 2997 int pair[2]; 2998 2999 pair[0] = regno; 3000 pair[1] = -1; 3001 while (splay_tree_foreach (pbi->reg_cond_dead, 3002 flush_reg_cond_reg_1, pair) == -1) 3003 splay_tree_remove (pbi->reg_cond_dead, pair[1]); 3004 3005 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno); 3006} 3007 3008/* Logical arithmetic on predicate conditions. IOR, NOT and AND. 3009 For ior/and, the ADD flag determines whether we want to add the new 3010 condition X to the old one unconditionally. If it is zero, we will 3011 only return a new expression if X allows us to simplify part of 3012 OLD, otherwise we return NULL to the caller. 3013 If ADD is nonzero, we will return a new condition in all cases. The 3014 toplevel caller of one of these functions should always pass 1 for 3015 ADD. */ 3016 3017static rtx 3018ior_reg_cond (rtx old, rtx x, int add) 3019{ 3020 rtx op0, op1; 3021 3022 if (GET_RTX_CLASS (GET_CODE (old)) == '<') 3023 { 3024 if (GET_RTX_CLASS (GET_CODE (x)) == '<' 3025 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old)) 3026 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3027 return const1_rtx; 3028 if (GET_CODE (x) == GET_CODE (old) 3029 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3030 return old; 3031 if (! add) 3032 return NULL; 3033 return gen_rtx_IOR (0, old, x); 3034 } 3035 3036 switch (GET_CODE (old)) 3037 { 3038 case IOR: 3039 op0 = ior_reg_cond (XEXP (old, 0), x, 0); 3040 op1 = ior_reg_cond (XEXP (old, 1), x, 0); 3041 if (op0 != NULL || op1 != NULL) 3042 { 3043 if (op0 == const0_rtx) 3044 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x); 3045 if (op1 == const0_rtx) 3046 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x); 3047 if (op0 == const1_rtx || op1 == const1_rtx) 3048 return const1_rtx; 3049 if (op0 == NULL) 3050 op0 = gen_rtx_IOR (0, XEXP (old, 0), x); 3051 else if (rtx_equal_p (x, op0)) 3052 /* (x | A) | x ~ (x | A). */ 3053 return old; 3054 if (op1 == NULL) 3055 op1 = gen_rtx_IOR (0, XEXP (old, 1), x); 3056 else if (rtx_equal_p (x, op1)) 3057 /* (A | x) | x ~ (A | x). */ 3058 return old; 3059 return gen_rtx_IOR (0, op0, op1); 3060 } 3061 if (! add) 3062 return NULL; 3063 return gen_rtx_IOR (0, old, x); 3064 3065 case AND: 3066 op0 = ior_reg_cond (XEXP (old, 0), x, 0); 3067 op1 = ior_reg_cond (XEXP (old, 1), x, 0); 3068 if (op0 != NULL || op1 != NULL) 3069 { 3070 if (op0 == const1_rtx) 3071 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x); 3072 if (op1 == const1_rtx) 3073 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x); 3074 if (op0 == const0_rtx || op1 == const0_rtx) 3075 return const0_rtx; 3076 if (op0 == NULL) 3077 op0 = gen_rtx_IOR (0, XEXP (old, 0), x); 3078 else if (rtx_equal_p (x, op0)) 3079 /* (x & A) | x ~ x. */ 3080 return op0; 3081 if (op1 == NULL) 3082 op1 = gen_rtx_IOR (0, XEXP (old, 1), x); 3083 else if (rtx_equal_p (x, op1)) 3084 /* (A & x) | x ~ x. */ 3085 return op1; 3086 return gen_rtx_AND (0, op0, op1); 3087 } 3088 if (! add) 3089 return NULL; 3090 return gen_rtx_IOR (0, old, x); 3091 3092 case NOT: 3093 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0); 3094 if (op0 != NULL) 3095 return not_reg_cond (op0); 3096 if (! add) 3097 return NULL; 3098 return gen_rtx_IOR (0, old, x); 3099 3100 default: 3101 abort (); 3102 } 3103} 3104 3105static rtx 3106not_reg_cond (rtx x) 3107{ 3108 enum rtx_code x_code; 3109 3110 if (x == const0_rtx) 3111 return const1_rtx; 3112 else if (x == const1_rtx) 3113 return const0_rtx; 3114 x_code = GET_CODE (x); 3115 if (x_code == NOT) 3116 return XEXP (x, 0); 3117 if (GET_RTX_CLASS (x_code) == '<' 3118 && GET_CODE (XEXP (x, 0)) == REG) 3119 { 3120 if (XEXP (x, 1) != const0_rtx) 3121 abort (); 3122 3123 return gen_rtx_fmt_ee (reverse_condition (x_code), 3124 VOIDmode, XEXP (x, 0), const0_rtx); 3125 } 3126 return gen_rtx_NOT (0, x); 3127} 3128 3129static rtx 3130and_reg_cond (rtx old, rtx x, int add) 3131{ 3132 rtx op0, op1; 3133 3134 if (GET_RTX_CLASS (GET_CODE (old)) == '<') 3135 { 3136 if (GET_RTX_CLASS (GET_CODE (x)) == '<' 3137 && GET_CODE (x) == reverse_condition (GET_CODE (old)) 3138 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3139 return const0_rtx; 3140 if (GET_CODE (x) == GET_CODE (old) 3141 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0))) 3142 return old; 3143 if (! add) 3144 return NULL; 3145 return gen_rtx_AND (0, old, x); 3146 } 3147 3148 switch (GET_CODE (old)) 3149 { 3150 case IOR: 3151 op0 = and_reg_cond (XEXP (old, 0), x, 0); 3152 op1 = and_reg_cond (XEXP (old, 1), x, 0); 3153 if (op0 != NULL || op1 != NULL) 3154 { 3155 if (op0 == const0_rtx) 3156 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x); 3157 if (op1 == const0_rtx) 3158 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x); 3159 if (op0 == const1_rtx || op1 == const1_rtx) 3160 return const1_rtx; 3161 if (op0 == NULL) 3162 op0 = gen_rtx_AND (0, XEXP (old, 0), x); 3163 else if (rtx_equal_p (x, op0)) 3164 /* (x | A) & x ~ x. */ 3165 return op0; 3166 if (op1 == NULL) 3167 op1 = gen_rtx_AND (0, XEXP (old, 1), x); 3168 else if (rtx_equal_p (x, op1)) 3169 /* (A | x) & x ~ x. */ 3170 return op1; 3171 return gen_rtx_IOR (0, op0, op1); 3172 } 3173 if (! add) 3174 return NULL; 3175 return gen_rtx_AND (0, old, x); 3176 3177 case AND: 3178 op0 = and_reg_cond (XEXP (old, 0), x, 0); 3179 op1 = and_reg_cond (XEXP (old, 1), x, 0); 3180 if (op0 != NULL || op1 != NULL) 3181 { 3182 if (op0 == const1_rtx) 3183 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x); 3184 if (op1 == const1_rtx) 3185 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x); 3186 if (op0 == const0_rtx || op1 == const0_rtx) 3187 return const0_rtx; 3188 if (op0 == NULL) 3189 op0 = gen_rtx_AND (0, XEXP (old, 0), x); 3190 else if (rtx_equal_p (x, op0)) 3191 /* (x & A) & x ~ (x & A). */ 3192 return old; 3193 if (op1 == NULL) 3194 op1 = gen_rtx_AND (0, XEXP (old, 1), x); 3195 else if (rtx_equal_p (x, op1)) 3196 /* (A & x) & x ~ (A & x). */ 3197 return old; 3198 return gen_rtx_AND (0, op0, op1); 3199 } 3200 if (! add) 3201 return NULL; 3202 return gen_rtx_AND (0, old, x); 3203 3204 case NOT: 3205 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0); 3206 if (op0 != NULL) 3207 return not_reg_cond (op0); 3208 if (! add) 3209 return NULL; 3210 return gen_rtx_AND (0, old, x); 3211 3212 default: 3213 abort (); 3214 } 3215} 3216 3217/* Given a condition X, remove references to reg REGNO and return the 3218 new condition. The removal will be done so that all conditions 3219 involving REGNO are considered to evaluate to false. This function 3220 is used when the value of REGNO changes. */ 3221 3222static rtx 3223elim_reg_cond (rtx x, unsigned int regno) 3224{ 3225 rtx op0, op1; 3226 3227 if (GET_RTX_CLASS (GET_CODE (x)) == '<') 3228 { 3229 if (REGNO (XEXP (x, 0)) == regno) 3230 return const0_rtx; 3231 return x; 3232 } 3233 3234 switch (GET_CODE (x)) 3235 { 3236 case AND: 3237 op0 = elim_reg_cond (XEXP (x, 0), regno); 3238 op1 = elim_reg_cond (XEXP (x, 1), regno); 3239 if (op0 == const0_rtx || op1 == const0_rtx) 3240 return const0_rtx; 3241 if (op0 == const1_rtx) 3242 return op1; 3243 if (op1 == const1_rtx) 3244 return op0; 3245 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1)) 3246 return x; 3247 return gen_rtx_AND (0, op0, op1); 3248 3249 case IOR: 3250 op0 = elim_reg_cond (XEXP (x, 0), regno); 3251 op1 = elim_reg_cond (XEXP (x, 1), regno); 3252 if (op0 == const1_rtx || op1 == const1_rtx) 3253 return const1_rtx; 3254 if (op0 == const0_rtx) 3255 return op1; 3256 if (op1 == const0_rtx) 3257 return op0; 3258 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1)) 3259 return x; 3260 return gen_rtx_IOR (0, op0, op1); 3261 3262 case NOT: 3263 op0 = elim_reg_cond (XEXP (x, 0), regno); 3264 if (op0 == const0_rtx) 3265 return const1_rtx; 3266 if (op0 == const1_rtx) 3267 return const0_rtx; 3268 if (op0 != XEXP (x, 0)) 3269 return not_reg_cond (op0); 3270 return x; 3271 3272 default: 3273 abort (); 3274 } 3275} 3276#endif /* HAVE_conditional_execution */ 3277 3278#ifdef AUTO_INC_DEC 3279 3280/* Try to substitute the auto-inc expression INC as the address inside 3281 MEM which occurs in INSN. Currently, the address of MEM is an expression 3282 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn 3283 that has a single set whose source is a PLUS of INCR_REG and something 3284 else. */ 3285 3286static void 3287attempt_auto_inc (struct propagate_block_info *pbi, rtx inc, rtx insn, 3288 rtx mem, rtx incr, rtx incr_reg) 3289{ 3290 int regno = REGNO (incr_reg); 3291 rtx set = single_set (incr); 3292 rtx q = SET_DEST (set); 3293 rtx y = SET_SRC (set); 3294 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1; 3295 3296 /* Make sure this reg appears only once in this insn. */ 3297 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1) 3298 return; 3299 3300 if (dead_or_set_p (incr, incr_reg) 3301 /* Mustn't autoinc an eliminable register. */ 3302 && (regno >= FIRST_PSEUDO_REGISTER 3303 || ! TEST_HARD_REG_BIT (elim_reg_set, regno))) 3304 { 3305 /* This is the simple case. Try to make the auto-inc. If 3306 we can't, we are done. Otherwise, we will do any 3307 needed updates below. */ 3308 if (! validate_change (insn, &XEXP (mem, 0), inc, 0)) 3309 return; 3310 } 3311 else if (GET_CODE (q) == REG 3312 /* PREV_INSN used here to check the semi-open interval 3313 [insn,incr). */ 3314 && ! reg_used_between_p (q, PREV_INSN (insn), incr) 3315 /* We must also check for sets of q as q may be 3316 a call clobbered hard register and there may 3317 be a call between PREV_INSN (insn) and incr. */ 3318 && ! reg_set_between_p (q, PREV_INSN (insn), incr)) 3319 { 3320 /* We have *p followed sometime later by q = p+size. 3321 Both p and q must be live afterward, 3322 and q is not used between INSN and its assignment. 3323 Change it to q = p, ...*q..., q = q+size. 3324 Then fall into the usual case. */ 3325 rtx insns, temp; 3326 3327 start_sequence (); 3328 emit_move_insn (q, incr_reg); 3329 insns = get_insns (); 3330 end_sequence (); 3331 3332 /* If we can't make the auto-inc, or can't make the 3333 replacement into Y, exit. There's no point in making 3334 the change below if we can't do the auto-inc and doing 3335 so is not correct in the pre-inc case. */ 3336 3337 XEXP (inc, 0) = q; 3338 validate_change (insn, &XEXP (mem, 0), inc, 1); 3339 validate_change (incr, &XEXP (y, opnum), q, 1); 3340 if (! apply_change_group ()) 3341 return; 3342 3343 /* We now know we'll be doing this change, so emit the 3344 new insn(s) and do the updates. */ 3345 emit_insn_before (insns, insn); 3346 3347 if (BB_HEAD (pbi->bb) == insn) 3348 BB_HEAD (pbi->bb) = insns; 3349 3350 /* INCR will become a NOTE and INSN won't contain a 3351 use of INCR_REG. If a use of INCR_REG was just placed in 3352 the insn before INSN, make that the next use. 3353 Otherwise, invalidate it. */ 3354 if (GET_CODE (PREV_INSN (insn)) == INSN 3355 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET 3356 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg) 3357 pbi->reg_next_use[regno] = PREV_INSN (insn); 3358 else 3359 pbi->reg_next_use[regno] = 0; 3360 3361 incr_reg = q; 3362 regno = REGNO (q); 3363 3364 /* REGNO is now used in INCR which is below INSN, but 3365 it previously wasn't live here. If we don't mark 3366 it as live, we'll put a REG_DEAD note for it 3367 on this insn, which is incorrect. */ 3368 SET_REGNO_REG_SET (pbi->reg_live, regno); 3369 3370 /* If there are any calls between INSN and INCR, show 3371 that REGNO now crosses them. */ 3372 for (temp = insn; temp != incr; temp = NEXT_INSN (temp)) 3373 if (GET_CODE (temp) == CALL_INSN) 3374 { 3375 REG_N_CALLS_CROSSED (regno)++; 3376 if (can_throw_internal (temp)) 3377 REG_N_THROWING_CALLS_CROSSED (regno)++; 3378 } 3379 3380 /* Invalidate alias info for Q since we just changed its value. */ 3381 clear_reg_alias_info (q); 3382 } 3383 else 3384 return; 3385 3386 /* If we haven't returned, it means we were able to make the 3387 auto-inc, so update the status. First, record that this insn 3388 has an implicit side effect. */ 3389 3390 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn)); 3391 3392 /* Modify the old increment-insn to simply copy 3393 the already-incremented value of our register. */ 3394 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0)) 3395 abort (); 3396 3397 /* If that makes it a no-op (copying the register into itself) delete 3398 it so it won't appear to be a "use" and a "set" of this 3399 register. */ 3400 if (REGNO (SET_DEST (set)) == REGNO (incr_reg)) 3401 { 3402 /* If the original source was dead, it's dead now. */ 3403 rtx note; 3404 3405 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX) 3406 { 3407 remove_note (incr, note); 3408 if (XEXP (note, 0) != incr_reg) 3409 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0))); 3410 } 3411 3412 PUT_CODE (incr, NOTE); 3413 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED; 3414 NOTE_SOURCE_FILE (incr) = 0; 3415 } 3416 3417 if (regno >= FIRST_PSEUDO_REGISTER) 3418 { 3419 /* Count an extra reference to the reg. When a reg is 3420 incremented, spilling it is worse, so we want to make 3421 that less likely. */ 3422 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb); 3423 3424 /* Count the increment as a setting of the register, 3425 even though it isn't a SET in rtl. */ 3426 REG_N_SETS (regno)++; 3427 } 3428} 3429 3430/* X is a MEM found in INSN. See if we can convert it into an auto-increment 3431 reference. */ 3432 3433static void 3434find_auto_inc (struct propagate_block_info *pbi, rtx x, rtx insn) 3435{ 3436 rtx addr = XEXP (x, 0); 3437 HOST_WIDE_INT offset = 0; 3438 rtx set, y, incr, inc_val; 3439 int regno; 3440 int size = GET_MODE_SIZE (GET_MODE (x)); 3441 3442 if (GET_CODE (insn) == JUMP_INSN) 3443 return; 3444 3445 /* Here we detect use of an index register which might be good for 3446 postincrement, postdecrement, preincrement, or predecrement. */ 3447 3448 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT) 3449 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0); 3450 3451 if (GET_CODE (addr) != REG) 3452 return; 3453 3454 regno = REGNO (addr); 3455 3456 /* Is the next use an increment that might make auto-increment? */ 3457 incr = pbi->reg_next_use[regno]; 3458 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn)) 3459 return; 3460 set = single_set (incr); 3461 if (set == 0 || GET_CODE (set) != SET) 3462 return; 3463 y = SET_SRC (set); 3464 3465 if (GET_CODE (y) != PLUS) 3466 return; 3467 3468 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr)) 3469 inc_val = XEXP (y, 1); 3470 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr)) 3471 inc_val = XEXP (y, 0); 3472 else 3473 return; 3474 3475 if (GET_CODE (inc_val) == CONST_INT) 3476 { 3477 if (HAVE_POST_INCREMENT 3478 && (INTVAL (inc_val) == size && offset == 0)) 3479 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x, 3480 incr, addr); 3481 else if (HAVE_POST_DECREMENT 3482 && (INTVAL (inc_val) == -size && offset == 0)) 3483 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x, 3484 incr, addr); 3485 else if (HAVE_PRE_INCREMENT 3486 && (INTVAL (inc_val) == size && offset == size)) 3487 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x, 3488 incr, addr); 3489 else if (HAVE_PRE_DECREMENT 3490 && (INTVAL (inc_val) == -size && offset == -size)) 3491 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x, 3492 incr, addr); 3493 else if (HAVE_POST_MODIFY_DISP && offset == 0) 3494 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr, 3495 gen_rtx_PLUS (Pmode, 3496 addr, 3497 inc_val)), 3498 insn, x, incr, addr); 3499 else if (HAVE_PRE_MODIFY_DISP && offset == INTVAL (inc_val)) 3500 attempt_auto_inc (pbi, gen_rtx_PRE_MODIFY (Pmode, addr, 3501 gen_rtx_PLUS (Pmode, 3502 addr, 3503 inc_val)), 3504 insn, x, incr, addr); 3505 } 3506 else if (GET_CODE (inc_val) == REG 3507 && ! reg_set_between_p (inc_val, PREV_INSN (insn), 3508 NEXT_INSN (incr))) 3509 3510 { 3511 if (HAVE_POST_MODIFY_REG && offset == 0) 3512 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr, 3513 gen_rtx_PLUS (Pmode, 3514 addr, 3515 inc_val)), 3516 insn, x, incr, addr); 3517 } 3518} 3519 3520#endif /* AUTO_INC_DEC */ 3521 3522static void 3523mark_used_reg (struct propagate_block_info *pbi, rtx reg, 3524 rtx cond ATTRIBUTE_UNUSED, rtx insn) 3525{ 3526 unsigned int regno_first, regno_last, i; 3527 int some_was_live, some_was_dead, some_not_set; 3528 3529 regno_last = regno_first = REGNO (reg); 3530 if (regno_first < FIRST_PSEUDO_REGISTER) 3531 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1; 3532 3533 /* Find out if any of this register is live after this instruction. */ 3534 some_was_live = some_was_dead = 0; 3535 for (i = regno_first; i <= regno_last; ++i) 3536 { 3537 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i); 3538 some_was_live |= needed_regno; 3539 some_was_dead |= ! needed_regno; 3540 } 3541 3542 /* Find out if any of the register was set this insn. */ 3543 some_not_set = 0; 3544 for (i = regno_first; i <= regno_last; ++i) 3545 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i); 3546 3547 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC)) 3548 { 3549 /* Record where each reg is used, so when the reg is set we know 3550 the next insn that uses it. */ 3551 pbi->reg_next_use[regno_first] = insn; 3552 } 3553 3554 if (pbi->flags & PROP_REG_INFO) 3555 { 3556 if (regno_first < FIRST_PSEUDO_REGISTER) 3557 { 3558 /* If this is a register we are going to try to eliminate, 3559 don't mark it live here. If we are successful in 3560 eliminating it, it need not be live unless it is used for 3561 pseudos, in which case it will have been set live when it 3562 was allocated to the pseudos. If the register will not 3563 be eliminated, reload will set it live at that point. 3564 3565 Otherwise, record that this function uses this register. */ 3566 /* ??? The PPC backend tries to "eliminate" on the pic 3567 register to itself. This should be fixed. In the mean 3568 time, hack around it. */ 3569 3570 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first) 3571 && (regno_first == FRAME_POINTER_REGNUM 3572 || regno_first == ARG_POINTER_REGNUM))) 3573 for (i = regno_first; i <= regno_last; ++i) 3574 regs_ever_live[i] = 1; 3575 } 3576 else 3577 { 3578 /* Keep track of which basic block each reg appears in. */ 3579 3580 int blocknum = pbi->bb->index; 3581 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN) 3582 REG_BASIC_BLOCK (regno_first) = blocknum; 3583 else if (REG_BASIC_BLOCK (regno_first) != blocknum) 3584 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL; 3585 3586 /* Count (weighted) number of uses of each reg. */ 3587 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb); 3588 REG_N_REFS (regno_first)++; 3589 } 3590 } 3591 3592 /* Record and count the insns in which a reg dies. If it is used in 3593 this insn and was dead below the insn then it dies in this insn. 3594 If it was set in this insn, we do not make a REG_DEAD note; 3595 likewise if we already made such a note. */ 3596 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO)) 3597 && some_was_dead 3598 && some_not_set) 3599 { 3600 /* Check for the case where the register dying partially 3601 overlaps the register set by this insn. */ 3602 if (regno_first != regno_last) 3603 for (i = regno_first; i <= regno_last; ++i) 3604 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i); 3605 3606 /* If none of the words in X is needed, make a REG_DEAD note. 3607 Otherwise, we must make partial REG_DEAD notes. */ 3608 if (! some_was_live) 3609 { 3610 if ((pbi->flags & PROP_DEATH_NOTES) 3611 && ! find_regno_note (insn, REG_DEAD, regno_first)) 3612 REG_NOTES (insn) 3613 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn)); 3614 3615 if (pbi->flags & PROP_REG_INFO) 3616 REG_N_DEATHS (regno_first)++; 3617 } 3618 else 3619 { 3620 /* Don't make a REG_DEAD note for a part of a register 3621 that is set in the insn. */ 3622 for (i = regno_first; i <= regno_last; ++i) 3623 if (! REGNO_REG_SET_P (pbi->reg_live, i) 3624 && ! dead_or_set_regno_p (insn, i)) 3625 REG_NOTES (insn) 3626 = alloc_EXPR_LIST (REG_DEAD, 3627 regno_reg_rtx[i], 3628 REG_NOTES (insn)); 3629 } 3630 } 3631 3632 /* Mark the register as being live. */ 3633 for (i = regno_first; i <= regno_last; ++i) 3634 { 3635#ifdef HAVE_conditional_execution 3636 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i); 3637#endif 3638 3639 SET_REGNO_REG_SET (pbi->reg_live, i); 3640 3641#ifdef HAVE_conditional_execution 3642 /* If this is a conditional use, record that fact. If it is later 3643 conditionally set, we'll know to kill the register. */ 3644 if (cond != NULL_RTX) 3645 { 3646 splay_tree_node node; 3647 struct reg_cond_life_info *rcli; 3648 rtx ncond; 3649 3650 if (this_was_live) 3651 { 3652 node = splay_tree_lookup (pbi->reg_cond_dead, i); 3653 if (node == NULL) 3654 { 3655 /* The register was unconditionally live previously. 3656 No need to do anything. */ 3657 } 3658 else 3659 { 3660 /* The register was conditionally live previously. 3661 Subtract the new life cond from the old death cond. */ 3662 rcli = (struct reg_cond_life_info *) node->value; 3663 ncond = rcli->condition; 3664 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1); 3665 3666 /* If the register is now unconditionally live, 3667 remove the entry in the splay_tree. */ 3668 if (ncond == const0_rtx) 3669 splay_tree_remove (pbi->reg_cond_dead, i); 3670 else 3671 { 3672 rcli->condition = ncond; 3673 SET_REGNO_REG_SET (pbi->reg_cond_reg, 3674 REGNO (XEXP (cond, 0))); 3675 } 3676 } 3677 } 3678 else 3679 { 3680 /* The register was not previously live at all. Record 3681 the condition under which it is still dead. */ 3682 rcli = xmalloc (sizeof (*rcli)); 3683 rcli->condition = not_reg_cond (cond); 3684 rcli->stores = const0_rtx; 3685 rcli->orig_condition = const0_rtx; 3686 splay_tree_insert (pbi->reg_cond_dead, i, 3687 (splay_tree_value) rcli); 3688 3689 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0))); 3690 } 3691 } 3692 else if (this_was_live) 3693 { 3694 /* The register may have been conditionally live previously, but 3695 is now unconditionally live. Remove it from the conditionally 3696 dead list, so that a conditional set won't cause us to think 3697 it dead. */ 3698 splay_tree_remove (pbi->reg_cond_dead, i); 3699 } 3700#endif 3701 } 3702} 3703 3704/* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses. 3705 This is done assuming the registers needed from X are those that 3706 have 1-bits in PBI->REG_LIVE. 3707 3708 INSN is the containing instruction. If INSN is dead, this function 3709 is not called. */ 3710 3711static void 3712mark_used_regs (struct propagate_block_info *pbi, rtx x, rtx cond, rtx insn) 3713{ 3714 RTX_CODE code; 3715 int regno; 3716 int flags = pbi->flags; 3717 3718 retry: 3719 if (!x) 3720 return; 3721 code = GET_CODE (x); 3722 switch (code) 3723 { 3724 case LABEL_REF: 3725 case SYMBOL_REF: 3726 case CONST_INT: 3727 case CONST: 3728 case CONST_DOUBLE: 3729 case CONST_VECTOR: 3730 case PC: 3731 case ADDR_VEC: 3732 case ADDR_DIFF_VEC: 3733 return; 3734 3735#ifdef HAVE_cc0 3736 case CC0: 3737 pbi->cc0_live = 1; 3738 return; 3739#endif 3740 3741 case CLOBBER: 3742 /* If we are clobbering a MEM, mark any registers inside the address 3743 as being used. */ 3744 if (GET_CODE (XEXP (x, 0)) == MEM) 3745 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn); 3746 return; 3747 3748 case MEM: 3749 /* Don't bother watching stores to mems if this is not the 3750 final pass. We'll not be deleting dead stores this round. */ 3751 if (optimize && (flags & PROP_SCAN_DEAD_STORES)) 3752 { 3753 /* Invalidate the data for the last MEM stored, but only if MEM is 3754 something that can be stored into. */ 3755 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF 3756 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0))) 3757 /* Needn't clear the memory set list. */ 3758 ; 3759 else 3760 { 3761 rtx temp = pbi->mem_set_list; 3762 rtx prev = NULL_RTX; 3763 rtx next; 3764 3765 while (temp) 3766 { 3767 next = XEXP (temp, 1); 3768 if (unchanging_anti_dependence (XEXP (temp, 0), x)) 3769 { 3770 /* Splice temp out of the list. */ 3771 if (prev) 3772 XEXP (prev, 1) = next; 3773 else 3774 pbi->mem_set_list = next; 3775 free_EXPR_LIST_node (temp); 3776 pbi->mem_set_list_len--; 3777 } 3778 else 3779 prev = temp; 3780 temp = next; 3781 } 3782 } 3783 3784 /* If the memory reference had embedded side effects (autoincrement 3785 address modes. Then we may need to kill some entries on the 3786 memory set list. */ 3787 if (insn) 3788 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi); 3789 } 3790 3791#ifdef AUTO_INC_DEC 3792 if (flags & PROP_AUTOINC) 3793 find_auto_inc (pbi, x, insn); 3794#endif 3795 break; 3796 3797 case SUBREG: 3798#ifdef CANNOT_CHANGE_MODE_CLASS 3799 if (flags & PROP_REG_INFO) 3800 record_subregs_of_mode (x); 3801#endif 3802 3803 /* While we're here, optimize this case. */ 3804 x = SUBREG_REG (x); 3805 if (GET_CODE (x) != REG) 3806 goto retry; 3807 /* Fall through. */ 3808 3809 case REG: 3810 /* See a register other than being set => mark it as needed. */ 3811 mark_used_reg (pbi, x, cond, insn); 3812 return; 3813 3814 case SET: 3815 { 3816 rtx testreg = SET_DEST (x); 3817 int mark_dest = 0; 3818 3819 /* If storing into MEM, don't show it as being used. But do 3820 show the address as being used. */ 3821 if (GET_CODE (testreg) == MEM) 3822 { 3823#ifdef AUTO_INC_DEC 3824 if (flags & PROP_AUTOINC) 3825 find_auto_inc (pbi, testreg, insn); 3826#endif 3827 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn); 3828 mark_used_regs (pbi, SET_SRC (x), cond, insn); 3829 return; 3830 } 3831 3832 /* Storing in STRICT_LOW_PART is like storing in a reg 3833 in that this SET might be dead, so ignore it in TESTREG. 3834 but in some other ways it is like using the reg. 3835 3836 Storing in a SUBREG or a bit field is like storing the entire 3837 register in that if the register's value is not used 3838 then this SET is not needed. */ 3839 while (GET_CODE (testreg) == STRICT_LOW_PART 3840 || GET_CODE (testreg) == ZERO_EXTRACT 3841 || GET_CODE (testreg) == SIGN_EXTRACT 3842 || GET_CODE (testreg) == SUBREG) 3843 { 3844#ifdef CANNOT_CHANGE_MODE_CLASS 3845 if ((flags & PROP_REG_INFO) && GET_CODE (testreg) == SUBREG) 3846 record_subregs_of_mode (testreg); 3847#endif 3848 3849 /* Modifying a single register in an alternate mode 3850 does not use any of the old value. But these other 3851 ways of storing in a register do use the old value. */ 3852 if (GET_CODE (testreg) == SUBREG 3853 && !((REG_BYTES (SUBREG_REG (testreg)) 3854 + UNITS_PER_WORD - 1) / UNITS_PER_WORD 3855 > (REG_BYTES (testreg) 3856 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)) 3857 ; 3858 else 3859 mark_dest = 1; 3860 3861 testreg = XEXP (testreg, 0); 3862 } 3863 3864 /* If this is a store into a register or group of registers, 3865 recursively scan the value being stored. */ 3866 3867 if ((GET_CODE (testreg) == PARALLEL 3868 && GET_MODE (testreg) == BLKmode) 3869 || (GET_CODE (testreg) == REG 3870 && (regno = REGNO (testreg), 3871 ! (regno == FRAME_POINTER_REGNUM 3872 && (! reload_completed || frame_pointer_needed))) 3873#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM 3874 && ! (regno == HARD_FRAME_POINTER_REGNUM 3875 && (! reload_completed || frame_pointer_needed)) 3876#endif 3877#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM 3878 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno]) 3879#endif 3880 )) 3881 { 3882 if (mark_dest) 3883 mark_used_regs (pbi, SET_DEST (x), cond, insn); 3884 mark_used_regs (pbi, SET_SRC (x), cond, insn); 3885 return; 3886 } 3887 } 3888 break; 3889 3890 case ASM_OPERANDS: 3891 case UNSPEC_VOLATILE: 3892 case TRAP_IF: 3893 case ASM_INPUT: 3894 { 3895 /* Traditional and volatile asm instructions must be considered to use 3896 and clobber all hard registers, all pseudo-registers and all of 3897 memory. So must TRAP_IF and UNSPEC_VOLATILE operations. 3898 3899 Consider for instance a volatile asm that changes the fpu rounding 3900 mode. An insn should not be moved across this even if it only uses 3901 pseudo-regs because it might give an incorrectly rounded result. 3902 3903 ?!? Unfortunately, marking all hard registers as live causes massive 3904 problems for the register allocator and marking all pseudos as live 3905 creates mountains of uninitialized variable warnings. 3906 3907 So for now, just clear the memory set list and mark any regs 3908 we can find in ASM_OPERANDS as used. */ 3909 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x)) 3910 { 3911 free_EXPR_LIST_list (&pbi->mem_set_list); 3912 pbi->mem_set_list_len = 0; 3913 } 3914 3915 /* For all ASM_OPERANDS, we must traverse the vector of input operands. 3916 We can not just fall through here since then we would be confused 3917 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate 3918 traditional asms unlike their normal usage. */ 3919 if (code == ASM_OPERANDS) 3920 { 3921 int j; 3922 3923 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++) 3924 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn); 3925 } 3926 break; 3927 } 3928 3929 case COND_EXEC: 3930 if (cond != NULL_RTX) 3931 abort (); 3932 3933 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn); 3934 3935 cond = COND_EXEC_TEST (x); 3936 x = COND_EXEC_CODE (x); 3937 goto retry; 3938 3939 default: 3940 break; 3941 } 3942 3943 /* Recursively scan the operands of this expression. */ 3944 3945 { 3946 const char * const fmt = GET_RTX_FORMAT (code); 3947 int i; 3948 3949 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 3950 { 3951 if (fmt[i] == 'e') 3952 { 3953 /* Tail recursive case: save a function call level. */ 3954 if (i == 0) 3955 { 3956 x = XEXP (x, 0); 3957 goto retry; 3958 } 3959 mark_used_regs (pbi, XEXP (x, i), cond, insn); 3960 } 3961 else if (fmt[i] == 'E') 3962 { 3963 int j; 3964 for (j = 0; j < XVECLEN (x, i); j++) 3965 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn); 3966 } 3967 } 3968 } 3969} 3970 3971#ifdef AUTO_INC_DEC 3972 3973static int 3974try_pre_increment_1 (struct propagate_block_info *pbi, rtx insn) 3975{ 3976 /* Find the next use of this reg. If in same basic block, 3977 make it do pre-increment or pre-decrement if appropriate. */ 3978 rtx x = single_set (insn); 3979 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1) 3980 * INTVAL (XEXP (SET_SRC (x), 1))); 3981 int regno = REGNO (SET_DEST (x)); 3982 rtx y = pbi->reg_next_use[regno]; 3983 if (y != 0 3984 && SET_DEST (x) != stack_pointer_rtx 3985 && BLOCK_NUM (y) == BLOCK_NUM (insn) 3986 /* Don't do this if the reg dies, or gets set in y; a standard addressing 3987 mode would be better. */ 3988 && ! dead_or_set_p (y, SET_DEST (x)) 3989 && try_pre_increment (y, SET_DEST (x), amount)) 3990 { 3991 /* We have found a suitable auto-increment and already changed 3992 insn Y to do it. So flush this increment instruction. */ 3993 propagate_block_delete_insn (insn); 3994 3995 /* Count a reference to this reg for the increment insn we are 3996 deleting. When a reg is incremented, spilling it is worse, 3997 so we want to make that less likely. */ 3998 if (regno >= FIRST_PSEUDO_REGISTER) 3999 { 4000 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb); 4001 REG_N_SETS (regno)++; 4002 } 4003 4004 /* Flush any remembered memories depending on the value of 4005 the incremented register. */ 4006 invalidate_mems_from_set (pbi, SET_DEST (x)); 4007 4008 return 1; 4009 } 4010 return 0; 4011} 4012 4013/* Try to change INSN so that it does pre-increment or pre-decrement 4014 addressing on register REG in order to add AMOUNT to REG. 4015 AMOUNT is negative for pre-decrement. 4016 Returns 1 if the change could be made. 4017 This checks all about the validity of the result of modifying INSN. */ 4018 4019static int 4020try_pre_increment (rtx insn, rtx reg, HOST_WIDE_INT amount) 4021{ 4022 rtx use; 4023 4024 /* Nonzero if we can try to make a pre-increment or pre-decrement. 4025 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */ 4026 int pre_ok = 0; 4027 /* Nonzero if we can try to make a post-increment or post-decrement. 4028 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,... 4029 It is possible for both PRE_OK and POST_OK to be nonzero if the machine 4030 supports both pre-inc and post-inc, or both pre-dec and post-dec. */ 4031 int post_ok = 0; 4032 4033 /* Nonzero if the opportunity actually requires post-inc or post-dec. */ 4034 int do_post = 0; 4035 4036 /* From the sign of increment, see which possibilities are conceivable 4037 on this target machine. */ 4038 if (HAVE_PRE_INCREMENT && amount > 0) 4039 pre_ok = 1; 4040 if (HAVE_POST_INCREMENT && amount > 0) 4041 post_ok = 1; 4042 4043 if (HAVE_PRE_DECREMENT && amount < 0) 4044 pre_ok = 1; 4045 if (HAVE_POST_DECREMENT && amount < 0) 4046 post_ok = 1; 4047 4048 if (! (pre_ok || post_ok)) 4049 return 0; 4050 4051 /* It is not safe to add a side effect to a jump insn 4052 because if the incremented register is spilled and must be reloaded 4053 there would be no way to store the incremented value back in memory. */ 4054 4055 if (GET_CODE (insn) == JUMP_INSN) 4056 return 0; 4057 4058 use = 0; 4059 if (pre_ok) 4060 use = find_use_as_address (PATTERN (insn), reg, 0); 4061 if (post_ok && (use == 0 || use == (rtx) (size_t) 1)) 4062 { 4063 use = find_use_as_address (PATTERN (insn), reg, -amount); 4064 do_post = 1; 4065 } 4066 4067 if (use == 0 || use == (rtx) (size_t) 1) 4068 return 0; 4069 4070 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount)) 4071 return 0; 4072 4073 /* See if this combination of instruction and addressing mode exists. */ 4074 if (! validate_change (insn, &XEXP (use, 0), 4075 gen_rtx_fmt_e (amount > 0 4076 ? (do_post ? POST_INC : PRE_INC) 4077 : (do_post ? POST_DEC : PRE_DEC), 4078 Pmode, reg), 0)) 4079 return 0; 4080 4081 /* Record that this insn now has an implicit side effect on X. */ 4082 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn)); 4083 return 1; 4084} 4085 4086#endif /* AUTO_INC_DEC */ 4087 4088/* Find the place in the rtx X where REG is used as a memory address. 4089 Return the MEM rtx that so uses it. 4090 If PLUSCONST is nonzero, search instead for a memory address equivalent to 4091 (plus REG (const_int PLUSCONST)). 4092 4093 If such an address does not appear, return 0. 4094 If REG appears more than once, or is used other than in such an address, 4095 return (rtx) 1. */ 4096 4097rtx 4098find_use_as_address (rtx x, rtx reg, HOST_WIDE_INT plusconst) 4099{ 4100 enum rtx_code code = GET_CODE (x); 4101 const char * const fmt = GET_RTX_FORMAT (code); 4102 int i; 4103 rtx value = 0; 4104 rtx tem; 4105 4106 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0) 4107 return x; 4108 4109 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS 4110 && XEXP (XEXP (x, 0), 0) == reg 4111 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT 4112 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst) 4113 return x; 4114 4115 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT) 4116 { 4117 /* If REG occurs inside a MEM used in a bit-field reference, 4118 that is unacceptable. */ 4119 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0) 4120 return (rtx) (size_t) 1; 4121 } 4122 4123 if (x == reg) 4124 return (rtx) (size_t) 1; 4125 4126 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 4127 { 4128 if (fmt[i] == 'e') 4129 { 4130 tem = find_use_as_address (XEXP (x, i), reg, plusconst); 4131 if (value == 0) 4132 value = tem; 4133 else if (tem != 0) 4134 return (rtx) (size_t) 1; 4135 } 4136 else if (fmt[i] == 'E') 4137 { 4138 int j; 4139 for (j = XVECLEN (x, i) - 1; j >= 0; j--) 4140 { 4141 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst); 4142 if (value == 0) 4143 value = tem; 4144 else if (tem != 0) 4145 return (rtx) (size_t) 1; 4146 } 4147 } 4148 } 4149 4150 return value; 4151} 4152 4153/* Write information about registers and basic blocks into FILE. 4154 This is part of making a debugging dump. */ 4155 4156void 4157dump_regset (regset r, FILE *outf) 4158{ 4159 int i; 4160 if (r == NULL) 4161 { 4162 fputs (" (nil)", outf); 4163 return; 4164 } 4165 4166 EXECUTE_IF_SET_IN_REG_SET (r, 0, i, 4167 { 4168 fprintf (outf, " %d", i); 4169 if (i < FIRST_PSEUDO_REGISTER) 4170 fprintf (outf, " [%s]", 4171 reg_names[i]); 4172 }); 4173} 4174 4175/* Print a human-readable representation of R on the standard error 4176 stream. This function is designed to be used from within the 4177 debugger. */ 4178 4179void 4180debug_regset (regset r) 4181{ 4182 dump_regset (r, stderr); 4183 putc ('\n', stderr); 4184} 4185 4186/* Recompute register set/reference counts immediately prior to register 4187 allocation. 4188 4189 This avoids problems with set/reference counts changing to/from values 4190 which have special meanings to the register allocators. 4191 4192 Additionally, the reference counts are the primary component used by the 4193 register allocators to prioritize pseudos for allocation to hard regs. 4194 More accurate reference counts generally lead to better register allocation. 4195 4196 F is the first insn to be scanned. 4197 4198 LOOP_STEP denotes how much loop_depth should be incremented per 4199 loop nesting level in order to increase the ref count more for 4200 references in a loop. 4201 4202 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and 4203 possibly other information which is used by the register allocators. */ 4204 4205void 4206recompute_reg_usage (rtx f ATTRIBUTE_UNUSED, int loop_step ATTRIBUTE_UNUSED) 4207{ 4208 allocate_reg_life_data (); 4209 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO); 4210} 4211 4212/* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of 4213 blocks. If BLOCKS is NULL, assume the universal set. Returns a count 4214 of the number of registers that died. */ 4215 4216int 4217count_or_remove_death_notes (sbitmap blocks, int kill) 4218{ 4219 int count = 0; 4220 int i; 4221 basic_block bb; 4222 4223 4224 /* This used to be a loop over all the blocks with a membership test 4225 inside the loop. That can be amazingly expensive on a large CFG 4226 when only a small number of bits are set in BLOCKs (for example, 4227 the calls from the scheduler typically have very few bits set). 4228 4229 For extra credit, someone should convert BLOCKS to a bitmap rather 4230 than an sbitmap. */ 4231 if (blocks) 4232 { 4233 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i, 4234 { 4235 count += count_or_remove_death_notes_bb (BASIC_BLOCK (i), kill); 4236 }); 4237 } 4238 else 4239 { 4240 FOR_EACH_BB (bb) 4241 { 4242 count += count_or_remove_death_notes_bb (bb, kill); 4243 } 4244 } 4245 4246 return count; 4247} 4248 4249/* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic 4250 block BB. Returns a count of the number of registers that died. */ 4251 4252static int 4253count_or_remove_death_notes_bb (basic_block bb, int kill) 4254{ 4255 int count = 0; 4256 rtx insn; 4257 4258 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn)) 4259 { 4260 if (INSN_P (insn)) 4261 { 4262 rtx *pprev = ®_NOTES (insn); 4263 rtx link = *pprev; 4264 4265 while (link) 4266 { 4267 switch (REG_NOTE_KIND (link)) 4268 { 4269 case REG_DEAD: 4270 if (GET_CODE (XEXP (link, 0)) == REG) 4271 { 4272 rtx reg = XEXP (link, 0); 4273 int n; 4274 4275 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER) 4276 n = 1; 4277 else 4278 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg)); 4279 count += n; 4280 } 4281 4282 /* Fall through. */ 4283 4284 case REG_UNUSED: 4285 if (kill) 4286 { 4287 rtx next = XEXP (link, 1); 4288 free_EXPR_LIST_node (link); 4289 *pprev = link = next; 4290 break; 4291 } 4292 /* Fall through. */ 4293 4294 default: 4295 pprev = &XEXP (link, 1); 4296 link = *pprev; 4297 break; 4298 } 4299 } 4300 } 4301 4302 if (insn == BB_END (bb)) 4303 break; 4304 } 4305 4306 return count; 4307} 4308 4309/* Clear LOG_LINKS fields of insns in a selected blocks or whole chain 4310 if blocks is NULL. */ 4311 4312static void 4313clear_log_links (sbitmap blocks) 4314{ 4315 rtx insn; 4316 int i; 4317 4318 if (!blocks) 4319 { 4320 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) 4321 if (INSN_P (insn)) 4322 free_INSN_LIST_list (&LOG_LINKS (insn)); 4323 } 4324 else 4325 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i, 4326 { 4327 basic_block bb = BASIC_BLOCK (i); 4328 4329 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); 4330 insn = NEXT_INSN (insn)) 4331 if (INSN_P (insn)) 4332 free_INSN_LIST_list (&LOG_LINKS (insn)); 4333 }); 4334} 4335 4336/* Given a register bitmap, turn on the bits in a HARD_REG_SET that 4337 correspond to the hard registers, if any, set in that map. This 4338 could be done far more efficiently by having all sorts of special-cases 4339 with moving single words, but probably isn't worth the trouble. */ 4340 4341void 4342reg_set_to_hard_reg_set (HARD_REG_SET *to, bitmap from) 4343{ 4344 int i; 4345 4346 EXECUTE_IF_SET_IN_BITMAP 4347 (from, 0, i, 4348 { 4349 if (i >= FIRST_PSEUDO_REGISTER) 4350 return; 4351 SET_HARD_REG_BIT (*to, i); 4352 }); 4353} 4354