jump.c revision 50397
1/* Optimize jump instructions, for GNU compiler. 2 Copyright (C) 1987, 88, 89, 91-97, 1998 Free Software Foundation, Inc. 3 4This file is part of GNU CC. 5 6GNU CC is free software; you can redistribute it and/or modify 7it under the terms of the GNU General Public License as published by 8the Free Software Foundation; either version 2, or (at your option) 9any later version. 10 11GNU CC is distributed in the hope that it will be useful, 12but WITHOUT ANY WARRANTY; without even the implied warranty of 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14GNU General Public License for more details. 15 16You should have received a copy of the GNU General Public License 17along with GNU CC; see the file COPYING. If not, write to 18the Free Software Foundation, 59 Temple Place - Suite 330, 19Boston, MA 02111-1307, USA. */ 20 21 22/* This is the jump-optimization pass of the compiler. 23 It is run two or three times: once before cse, sometimes once after cse, 24 and once after reload (before final). 25 26 jump_optimize deletes unreachable code and labels that are not used. 27 It also deletes jumps that jump to the following insn, 28 and simplifies jumps around unconditional jumps and jumps 29 to unconditional jumps. 30 31 Each CODE_LABEL has a count of the times it is used 32 stored in the LABEL_NUSES internal field, and each JUMP_INSN 33 has one label that it refers to stored in the 34 JUMP_LABEL internal field. With this we can detect labels that 35 become unused because of the deletion of all the jumps that 36 formerly used them. The JUMP_LABEL info is sometimes looked 37 at by later passes. 38 39 Optionally, cross-jumping can be done. Currently it is done 40 only the last time (when after reload and before final). 41 In fact, the code for cross-jumping now assumes that register 42 allocation has been done, since it uses `rtx_renumbered_equal_p'. 43 44 Jump optimization is done after cse when cse's constant-propagation 45 causes jumps to become unconditional or to be deleted. 46 47 Unreachable loops are not detected here, because the labels 48 have references and the insns appear reachable from the labels. 49 find_basic_blocks in flow.c finds and deletes such loops. 50 51 The subroutines delete_insn, redirect_jump, and invert_jump are used 52 from other passes as well. */ 53 54#include "config.h" 55#include "system.h" 56#include "rtl.h" 57#include "flags.h" 58#include "hard-reg-set.h" 59#include "regs.h" 60#include "insn-config.h" 61#include "insn-flags.h" 62#include "insn-attr.h" 63#include "recog.h" 64#include "expr.h" 65#include "real.h" 66#include "except.h" 67#include "toplev.h" 68 69/* ??? Eventually must record somehow the labels used by jumps 70 from nested functions. */ 71/* Pre-record the next or previous real insn for each label? 72 No, this pass is very fast anyway. */ 73/* Condense consecutive labels? 74 This would make life analysis faster, maybe. */ 75/* Optimize jump y; x: ... y: jumpif... x? 76 Don't know if it is worth bothering with. */ 77/* Optimize two cases of conditional jump to conditional jump? 78 This can never delete any instruction or make anything dead, 79 or even change what is live at any point. 80 So perhaps let combiner do it. */ 81 82/* Vector indexed by uid. 83 For each CODE_LABEL, index by its uid to get first unconditional jump 84 that jumps to the label. 85 For each JUMP_INSN, index by its uid to get the next unconditional jump 86 that jumps to the same label. 87 Element 0 is the start of a chain of all return insns. 88 (It is safe to use element 0 because insn uid 0 is not used. */ 89 90static rtx *jump_chain; 91 92/* List of labels referred to from initializers. 93 These can never be deleted. */ 94rtx forced_labels; 95 96/* Maximum index in jump_chain. */ 97 98static int max_jump_chain; 99 100/* Set nonzero by jump_optimize if control can fall through 101 to the end of the function. */ 102int can_reach_end; 103 104/* Indicates whether death notes are significant in cross jump analysis. 105 Normally they are not significant, because of A and B jump to C, 106 and R dies in A, it must die in B. But this might not be true after 107 stack register conversion, and we must compare death notes in that 108 case. */ 109 110static int cross_jump_death_matters = 0; 111 112static int duplicate_loop_exit_test PROTO((rtx)); 113static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *)); 114static void do_cross_jump PROTO((rtx, rtx, rtx)); 115static int jump_back_p PROTO((rtx, rtx)); 116static int tension_vector_labels PROTO((rtx, int)); 117static void mark_jump_label PROTO((rtx, rtx, int)); 118static void delete_computation PROTO((rtx)); 119static void delete_from_jump_chain PROTO((rtx)); 120static int delete_labelref_insn PROTO((rtx, rtx, int)); 121static void mark_modified_reg PROTO((rtx, rtx)); 122static void redirect_tablejump PROTO((rtx, rtx)); 123#ifndef HAVE_cc0 124static rtx find_insert_position PROTO((rtx, rtx)); 125#endif 126 127/* Delete no-op jumps and optimize jumps to jumps 128 and jumps around jumps. 129 Delete unused labels and unreachable code. 130 131 If CROSS_JUMP is 1, detect matching code 132 before a jump and its destination and unify them. 133 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes. 134 135 If NOOP_MOVES is nonzero, delete no-op move insns. 136 137 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately 138 after regscan, and it is safe to use regno_first_uid and regno_last_uid. 139 140 If `optimize' is zero, don't change any code, 141 just determine whether control drops off the end of the function. 142 This case occurs when we have -W and not -O. 143 It works because `delete_insn' checks the value of `optimize' 144 and refrains from actually deleting when that is 0. */ 145 146void 147jump_optimize (f, cross_jump, noop_moves, after_regscan) 148 rtx f; 149 int cross_jump; 150 int noop_moves; 151 int after_regscan; 152{ 153 register rtx insn, next, note; 154 int changed; 155 int old_max_reg; 156 int first = 1; 157 int max_uid = 0; 158 rtx last_insn; 159 160 cross_jump_death_matters = (cross_jump == 2); 161 162 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL 163 notes whose labels don't occur in the insn any more. */ 164 165 for (insn = f; insn; insn = NEXT_INSN (insn)) 166 { 167 if (GET_CODE (insn) == CODE_LABEL) 168 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0); 169 else if (GET_CODE (insn) == JUMP_INSN) 170 JUMP_LABEL (insn) = 0; 171 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN) 172 for (note = REG_NOTES (insn); note; note = next) 173 { 174 next = XEXP (note, 1); 175 if (REG_NOTE_KIND (note) == REG_LABEL 176 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn))) 177 remove_note (insn, note); 178 } 179 180 if (INSN_UID (insn) > max_uid) 181 max_uid = INSN_UID (insn); 182 } 183 184 max_uid++; 185 186 /* If we are performing cross jump optimizations, then initialize 187 tables mapping UIDs to EH regions to avoid incorrect movement 188 of insns from one EH region to another. */ 189 if (flag_exceptions && cross_jump) 190 init_insn_eh_region (f, max_uid); 191 192 /* Delete insns following barriers, up to next label. */ 193 194 for (insn = f; insn;) 195 { 196 if (GET_CODE (insn) == BARRIER) 197 { 198 insn = NEXT_INSN (insn); 199 while (insn != 0 && GET_CODE (insn) != CODE_LABEL) 200 { 201 if (GET_CODE (insn) == NOTE 202 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END) 203 insn = NEXT_INSN (insn); 204 else 205 insn = delete_insn (insn); 206 } 207 /* INSN is now the code_label. */ 208 } 209 else 210 insn = NEXT_INSN (insn); 211 } 212 213 /* Leave some extra room for labels and duplicate exit test insns 214 we make. */ 215 max_jump_chain = max_uid * 14 / 10; 216 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx)); 217 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx)); 218 219 /* Mark the label each jump jumps to. 220 Combine consecutive labels, and count uses of labels. 221 222 For each label, make a chain (using `jump_chain') 223 of all the *unconditional* jumps that jump to it; 224 also make a chain of all returns. */ 225 226 for (insn = f; insn; insn = NEXT_INSN (insn)) 227 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') 228 { 229 mark_jump_label (PATTERN (insn), insn, cross_jump); 230 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN) 231 { 232 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn)) 233 { 234 jump_chain[INSN_UID (insn)] 235 = jump_chain[INSN_UID (JUMP_LABEL (insn))]; 236 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn; 237 } 238 if (GET_CODE (PATTERN (insn)) == RETURN) 239 { 240 jump_chain[INSN_UID (insn)] = jump_chain[0]; 241 jump_chain[0] = insn; 242 } 243 } 244 } 245 246 /* Keep track of labels used from static data; 247 they cannot ever be deleted. */ 248 249 for (insn = forced_labels; insn; insn = XEXP (insn, 1)) 250 LABEL_NUSES (XEXP (insn, 0))++; 251 252 check_exception_handler_labels (); 253 254 /* Keep track of labels used for marking handlers for exception 255 regions; they cannot usually be deleted. */ 256 257 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1)) 258 LABEL_NUSES (XEXP (insn, 0))++; 259 260 exception_optimize (); 261 262 /* Delete all labels already not referenced. 263 Also find the last insn. */ 264 265 last_insn = 0; 266 for (insn = f; insn; ) 267 { 268 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0) 269 insn = delete_insn (insn); 270 else 271 { 272 last_insn = insn; 273 insn = NEXT_INSN (insn); 274 } 275 } 276 277 if (!optimize) 278 { 279 /* See if there is still a NOTE_INSN_FUNCTION_END in this function. 280 If so record that this function can drop off the end. */ 281 282 insn = last_insn; 283 { 284 int n_labels = 1; 285 while (insn 286 /* One label can follow the end-note: the return label. */ 287 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0) 288 /* Ordinary insns can follow it if returning a structure. */ 289 || GET_CODE (insn) == INSN 290 /* If machine uses explicit RETURN insns, no epilogue, 291 then one of them follows the note. */ 292 || (GET_CODE (insn) == JUMP_INSN 293 && GET_CODE (PATTERN (insn)) == RETURN) 294 /* A barrier can follow the return insn. */ 295 || GET_CODE (insn) == BARRIER 296 /* Other kinds of notes can follow also. */ 297 || (GET_CODE (insn) == NOTE 298 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END))) 299 insn = PREV_INSN (insn); 300 } 301 302 /* Report if control can fall through at the end of the function. */ 303 if (insn && GET_CODE (insn) == NOTE 304 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END 305 && ! INSN_DELETED_P (insn)) 306 can_reach_end = 1; 307 308 /* Zero the "deleted" flag of all the "deleted" insns. */ 309 for (insn = f; insn; insn = NEXT_INSN (insn)) 310 INSN_DELETED_P (insn) = 0; 311 312 /* Show that the jump chain is not valid. */ 313 jump_chain = 0; 314 return; 315 } 316 317#ifdef HAVE_return 318 if (HAVE_return) 319 { 320 /* If we fall through to the epilogue, see if we can insert a RETURN insn 321 in front of it. If the machine allows it at this point (we might be 322 after reload for a leaf routine), it will improve optimization for it 323 to be there. */ 324 insn = get_last_insn (); 325 while (insn && GET_CODE (insn) == NOTE) 326 insn = PREV_INSN (insn); 327 328 if (insn && GET_CODE (insn) != BARRIER) 329 { 330 emit_jump_insn (gen_return ()); 331 emit_barrier (); 332 } 333 } 334#endif 335 336 if (noop_moves) 337 for (insn = f; insn; ) 338 { 339 next = NEXT_INSN (insn); 340 341 if (GET_CODE (insn) == INSN) 342 { 343 register rtx body = PATTERN (insn); 344 345/* Combine stack_adjusts with following push_insns. */ 346#ifdef PUSH_ROUNDING 347 if (GET_CODE (body) == SET 348 && SET_DEST (body) == stack_pointer_rtx 349 && GET_CODE (SET_SRC (body)) == PLUS 350 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx 351 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT 352 && INTVAL (XEXP (SET_SRC (body), 1)) > 0) 353 { 354 rtx p; 355 rtx stack_adjust_insn = insn; 356 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1)); 357 int total_pushed = 0; 358 int pushes = 0; 359 360 /* Find all successive push insns. */ 361 p = insn; 362 /* Don't convert more than three pushes; 363 that starts adding too many displaced addresses 364 and the whole thing starts becoming a losing 365 proposition. */ 366 while (pushes < 3) 367 { 368 rtx pbody, dest; 369 p = next_nonnote_insn (p); 370 if (p == 0 || GET_CODE (p) != INSN) 371 break; 372 pbody = PATTERN (p); 373 if (GET_CODE (pbody) != SET) 374 break; 375 dest = SET_DEST (pbody); 376 /* Allow a no-op move between the adjust and the push. */ 377 if (GET_CODE (dest) == REG 378 && GET_CODE (SET_SRC (pbody)) == REG 379 && REGNO (dest) == REGNO (SET_SRC (pbody))) 380 continue; 381 if (! (GET_CODE (dest) == MEM 382 && GET_CODE (XEXP (dest, 0)) == POST_INC 383 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx)) 384 break; 385 pushes++; 386 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody))) 387 > stack_adjust_amount) 388 break; 389 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody))); 390 } 391 392 /* Discard the amount pushed from the stack adjust; 393 maybe eliminate it entirely. */ 394 if (total_pushed >= stack_adjust_amount) 395 { 396 delete_computation (stack_adjust_insn); 397 total_pushed = stack_adjust_amount; 398 } 399 else 400 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1) 401 = GEN_INT (stack_adjust_amount - total_pushed); 402 403 /* Change the appropriate push insns to ordinary stores. */ 404 p = insn; 405 while (total_pushed > 0) 406 { 407 rtx pbody, dest; 408 p = next_nonnote_insn (p); 409 if (GET_CODE (p) != INSN) 410 break; 411 pbody = PATTERN (p); 412 if (GET_CODE (pbody) != SET) 413 break; 414 dest = SET_DEST (pbody); 415 /* Allow a no-op move between the adjust and the push. */ 416 if (GET_CODE (dest) == REG 417 && GET_CODE (SET_SRC (pbody)) == REG 418 && REGNO (dest) == REGNO (SET_SRC (pbody))) 419 continue; 420 if (! (GET_CODE (dest) == MEM 421 && GET_CODE (XEXP (dest, 0)) == POST_INC 422 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx)) 423 break; 424 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody))); 425 /* If this push doesn't fully fit in the space 426 of the stack adjust that we deleted, 427 make another stack adjust here for what we 428 didn't use up. There should be peepholes 429 to recognize the resulting sequence of insns. */ 430 if (total_pushed < 0) 431 { 432 emit_insn_before (gen_add2_insn (stack_pointer_rtx, 433 GEN_INT (- total_pushed)), 434 p); 435 break; 436 } 437 XEXP (dest, 0) 438 = plus_constant (stack_pointer_rtx, total_pushed); 439 } 440 } 441#endif 442 443 /* Detect and delete no-op move instructions 444 resulting from not allocating a parameter in a register. */ 445 446 if (GET_CODE (body) == SET 447 && (SET_DEST (body) == SET_SRC (body) 448 || (GET_CODE (SET_DEST (body)) == MEM 449 && GET_CODE (SET_SRC (body)) == MEM 450 && rtx_equal_p (SET_SRC (body), SET_DEST (body)))) 451 && ! (GET_CODE (SET_DEST (body)) == MEM 452 && MEM_VOLATILE_P (SET_DEST (body))) 453 && ! (GET_CODE (SET_SRC (body)) == MEM 454 && MEM_VOLATILE_P (SET_SRC (body)))) 455 delete_computation (insn); 456 457 /* Detect and ignore no-op move instructions 458 resulting from smart or fortuitous register allocation. */ 459 460 else if (GET_CODE (body) == SET) 461 { 462 int sreg = true_regnum (SET_SRC (body)); 463 int dreg = true_regnum (SET_DEST (body)); 464 465 if (sreg == dreg && sreg >= 0) 466 delete_insn (insn); 467 else if (sreg >= 0 && dreg >= 0) 468 { 469 rtx trial; 470 rtx tem = find_equiv_reg (NULL_RTX, insn, 0, 471 sreg, NULL_PTR, dreg, 472 GET_MODE (SET_SRC (body))); 473 474 if (tem != 0 475 && GET_MODE (tem) == GET_MODE (SET_DEST (body))) 476 { 477 /* DREG may have been the target of a REG_DEAD note in 478 the insn which makes INSN redundant. If so, reorg 479 would still think it is dead. So search for such a 480 note and delete it if we find it. */ 481 if (! find_regno_note (insn, REG_UNUSED, dreg)) 482 for (trial = prev_nonnote_insn (insn); 483 trial && GET_CODE (trial) != CODE_LABEL; 484 trial = prev_nonnote_insn (trial)) 485 if (find_regno_note (trial, REG_DEAD, dreg)) 486 { 487 remove_death (dreg, trial); 488 break; 489 } 490#ifdef PRESERVE_DEATH_INFO_REGNO_P 491 /* Deleting insn could lose a death-note for SREG 492 so don't do it if final needs accurate 493 death-notes. */ 494 if (PRESERVE_DEATH_INFO_REGNO_P (sreg) 495 && (trial = find_regno_note (insn, REG_DEAD, sreg))) 496 { 497 /* Change this into a USE so that we won't emit 498 code for it, but still can keep the note. */ 499 PATTERN (insn) 500 = gen_rtx_USE (VOIDmode, XEXP (trial, 0)); 501 INSN_CODE (insn) = -1; 502 /* Remove all reg notes but the REG_DEAD one. */ 503 REG_NOTES (insn) = trial; 504 XEXP (trial, 1) = NULL_RTX; 505 } 506 else 507#endif 508 delete_insn (insn); 509 } 510 } 511 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body)) 512 && find_equiv_reg (SET_SRC (body), insn, 0, dreg, 513 NULL_PTR, 0, 514 GET_MODE (SET_DEST (body)))) 515 { 516 /* This handles the case where we have two consecutive 517 assignments of the same constant to pseudos that didn't 518 get a hard reg. Each SET from the constant will be 519 converted into a SET of the spill register and an 520 output reload will be made following it. This produces 521 two loads of the same constant into the same spill 522 register. */ 523 524 rtx in_insn = insn; 525 526 /* Look back for a death note for the first reg. 527 If there is one, it is no longer accurate. */ 528 while (in_insn && GET_CODE (in_insn) != CODE_LABEL) 529 { 530 if ((GET_CODE (in_insn) == INSN 531 || GET_CODE (in_insn) == JUMP_INSN) 532 && find_regno_note (in_insn, REG_DEAD, dreg)) 533 { 534 remove_death (dreg, in_insn); 535 break; 536 } 537 in_insn = PREV_INSN (in_insn); 538 } 539 540 /* Delete the second load of the value. */ 541 delete_insn (insn); 542 } 543 } 544 else if (GET_CODE (body) == PARALLEL) 545 { 546 /* If each part is a set between two identical registers or 547 a USE or CLOBBER, delete the insn. */ 548 int i, sreg, dreg; 549 rtx tem; 550 551 for (i = XVECLEN (body, 0) - 1; i >= 0; i--) 552 { 553 tem = XVECEXP (body, 0, i); 554 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER) 555 continue; 556 557 if (GET_CODE (tem) != SET 558 || (sreg = true_regnum (SET_SRC (tem))) < 0 559 || (dreg = true_regnum (SET_DEST (tem))) < 0 560 || dreg != sreg) 561 break; 562 } 563 564 if (i < 0) 565 delete_insn (insn); 566 } 567 /* Also delete insns to store bit fields if they are no-ops. */ 568 /* Not worth the hair to detect this in the big-endian case. */ 569 else if (! BYTES_BIG_ENDIAN 570 && GET_CODE (body) == SET 571 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT 572 && XEXP (SET_DEST (body), 2) == const0_rtx 573 && XEXP (SET_DEST (body), 0) == SET_SRC (body) 574 && ! (GET_CODE (SET_SRC (body)) == MEM 575 && MEM_VOLATILE_P (SET_SRC (body)))) 576 delete_insn (insn); 577 } 578 insn = next; 579 } 580 581 /* If we haven't yet gotten to reload and we have just run regscan, 582 delete any insn that sets a register that isn't used elsewhere. 583 This helps some of the optimizations below by having less insns 584 being jumped around. */ 585 586 if (! reload_completed && after_regscan) 587 for (insn = f; insn; insn = next) 588 { 589 rtx set = single_set (insn); 590 591 next = NEXT_INSN (insn); 592 593 if (set && GET_CODE (SET_DEST (set)) == REG 594 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER 595 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn) 596 /* We use regno_last_note_uid so as not to delete the setting 597 of a reg that's used in notes. A subsequent optimization 598 might arrange to use that reg for real. */ 599 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn) 600 && ! side_effects_p (SET_SRC (set)) 601 && ! find_reg_note (insn, REG_RETVAL, 0)) 602 delete_insn (insn); 603 } 604 605 /* Now iterate optimizing jumps until nothing changes over one pass. */ 606 changed = 1; 607 old_max_reg = max_reg_num (); 608 while (changed) 609 { 610 changed = 0; 611 612 for (insn = f; insn; insn = next) 613 { 614 rtx reallabelprev; 615 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6; 616 rtx nlabel; 617 int this_is_simplejump, this_is_condjump, reversep = 0; 618 int this_is_condjump_in_parallel; 619 620#if 0 621 /* If NOT the first iteration, if this is the last jump pass 622 (just before final), do the special peephole optimizations. 623 Avoiding the first iteration gives ordinary jump opts 624 a chance to work before peephole opts. */ 625 626 if (reload_completed && !first && !flag_no_peephole) 627 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN) 628 peephole (insn); 629#endif 630 631 /* That could have deleted some insns after INSN, so check now 632 what the following insn is. */ 633 634 next = NEXT_INSN (insn); 635 636 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional 637 jump. Try to optimize by duplicating the loop exit test if so. 638 This is only safe immediately after regscan, because it uses 639 the values of regno_first_uid and regno_last_uid. */ 640 if (after_regscan && GET_CODE (insn) == NOTE 641 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG 642 && (temp1 = next_nonnote_insn (insn)) != 0 643 && simplejump_p (temp1)) 644 { 645 temp = PREV_INSN (insn); 646 if (duplicate_loop_exit_test (insn)) 647 { 648 changed = 1; 649 next = NEXT_INSN (temp); 650 continue; 651 } 652 } 653 654 if (GET_CODE (insn) != JUMP_INSN) 655 continue; 656 657 this_is_simplejump = simplejump_p (insn); 658 this_is_condjump = condjump_p (insn); 659 this_is_condjump_in_parallel = condjump_in_parallel_p (insn); 660 661 /* Tension the labels in dispatch tables. */ 662 663 if (GET_CODE (PATTERN (insn)) == ADDR_VEC) 664 changed |= tension_vector_labels (PATTERN (insn), 0); 665 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) 666 changed |= tension_vector_labels (PATTERN (insn), 1); 667 668 /* If a dispatch table always goes to the same place, 669 get rid of it and replace the insn that uses it. */ 670 671 if (GET_CODE (PATTERN (insn)) == ADDR_VEC 672 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) 673 { 674 int i; 675 rtx pat = PATTERN (insn); 676 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC; 677 int len = XVECLEN (pat, diff_vec_p); 678 rtx dispatch = prev_real_insn (insn); 679 680 for (i = 0; i < len; i++) 681 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0) 682 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0)) 683 break; 684 if (i == len 685 && dispatch != 0 686 && GET_CODE (dispatch) == JUMP_INSN 687 && JUMP_LABEL (dispatch) != 0 688 /* Don't mess with a casesi insn. */ 689 && !(GET_CODE (PATTERN (dispatch)) == SET 690 && (GET_CODE (SET_SRC (PATTERN (dispatch))) 691 == IF_THEN_ELSE)) 692 && next_real_insn (JUMP_LABEL (dispatch)) == insn) 693 { 694 redirect_tablejump (dispatch, 695 XEXP (XVECEXP (pat, diff_vec_p, 0), 0)); 696 changed = 1; 697 } 698 } 699 700 reallabelprev = prev_active_insn (JUMP_LABEL (insn)); 701 702 /* If a jump references the end of the function, try to turn 703 it into a RETURN insn, possibly a conditional one. */ 704 if (JUMP_LABEL (insn) 705 && (next_active_insn (JUMP_LABEL (insn)) == 0 706 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn)))) 707 == RETURN)) 708 changed |= redirect_jump (insn, NULL_RTX); 709 710 /* Detect jump to following insn. */ 711 if (reallabelprev == insn && condjump_p (insn)) 712 { 713 next = next_real_insn (JUMP_LABEL (insn)); 714 delete_jump (insn); 715 changed = 1; 716 continue; 717 } 718 719 /* If we have an unconditional jump preceded by a USE, try to put 720 the USE before the target and jump there. This simplifies many 721 of the optimizations below since we don't have to worry about 722 dealing with these USE insns. We only do this if the label 723 being branch to already has the identical USE or if code 724 never falls through to that label. */ 725 726 if (this_is_simplejump 727 && (temp = prev_nonnote_insn (insn)) != 0 728 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE 729 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0 730 && (GET_CODE (temp1) == BARRIER 731 || (GET_CODE (temp1) == INSN 732 && rtx_equal_p (PATTERN (temp), PATTERN (temp1)))) 733 /* Don't do this optimization if we have a loop containing only 734 the USE instruction, and the loop start label has a usage 735 count of 1. This is because we will redo this optimization 736 everytime through the outer loop, and jump opt will never 737 exit. */ 738 && ! ((temp2 = prev_nonnote_insn (temp)) != 0 739 && temp2 == JUMP_LABEL (insn) 740 && LABEL_NUSES (temp2) == 1)) 741 { 742 if (GET_CODE (temp1) == BARRIER) 743 { 744 emit_insn_after (PATTERN (temp), temp1); 745 temp1 = NEXT_INSN (temp1); 746 } 747 748 delete_insn (temp); 749 redirect_jump (insn, get_label_before (temp1)); 750 reallabelprev = prev_real_insn (temp1); 751 changed = 1; 752 } 753 754 /* Simplify if (...) x = a; else x = b; by converting it 755 to x = b; if (...) x = a; 756 if B is sufficiently simple, the test doesn't involve X, 757 and nothing in the test modifies B or X. 758 759 If we have small register classes, we also can't do this if X 760 is a hard register. 761 762 If the "x = b;" insn has any REG_NOTES, we don't do this because 763 of the possibility that we are running after CSE and there is a 764 REG_EQUAL note that is only valid if the branch has already been 765 taken. If we move the insn with the REG_EQUAL note, we may 766 fold the comparison to always be false in a later CSE pass. 767 (We could also delete the REG_NOTES when moving the insn, but it 768 seems simpler to not move it.) An exception is that we can move 769 the insn if the only note is a REG_EQUAL or REG_EQUIV whose 770 value is the same as "b". 771 772 INSN is the branch over the `else' part. 773 774 We set: 775 776 TEMP to the jump insn preceding "x = a;" 777 TEMP1 to X 778 TEMP2 to the insn that sets "x = b;" 779 TEMP3 to the insn that sets "x = a;" 780 TEMP4 to the set of "x = b"; */ 781 782 if (this_is_simplejump 783 && (temp3 = prev_active_insn (insn)) != 0 784 && GET_CODE (temp3) == INSN 785 && (temp4 = single_set (temp3)) != 0 786 && GET_CODE (temp1 = SET_DEST (temp4)) == REG 787 && (! SMALL_REGISTER_CLASSES 788 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER) 789 && (temp2 = next_active_insn (insn)) != 0 790 && GET_CODE (temp2) == INSN 791 && (temp4 = single_set (temp2)) != 0 792 && rtx_equal_p (SET_DEST (temp4), temp1) 793 && ! side_effects_p (SET_SRC (temp4)) 794 && ! may_trap_p (SET_SRC (temp4)) 795 && (REG_NOTES (temp2) == 0 796 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL 797 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV) 798 && XEXP (REG_NOTES (temp2), 1) == 0 799 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0), 800 SET_SRC (temp4)))) 801 && (temp = prev_active_insn (temp3)) != 0 802 && condjump_p (temp) && ! simplejump_p (temp) 803 /* TEMP must skip over the "x = a;" insn */ 804 && prev_real_insn (JUMP_LABEL (temp)) == insn 805 && no_labels_between_p (insn, JUMP_LABEL (temp)) 806 /* There must be no other entries to the "x = b;" insn. */ 807 && no_labels_between_p (JUMP_LABEL (temp), temp2) 808 /* INSN must either branch to the insn after TEMP2 or the insn 809 after TEMP2 must branch to the same place as INSN. */ 810 && (reallabelprev == temp2 811 || ((temp5 = next_active_insn (temp2)) != 0 812 && simplejump_p (temp5) 813 && JUMP_LABEL (temp5) == JUMP_LABEL (insn)))) 814 { 815 /* The test expression, X, may be a complicated test with 816 multiple branches. See if we can find all the uses of 817 the label that TEMP branches to without hitting a CALL_INSN 818 or a jump to somewhere else. */ 819 rtx target = JUMP_LABEL (temp); 820 int nuses = LABEL_NUSES (target); 821 rtx p; 822#ifdef HAVE_cc0 823 rtx q; 824#endif 825 826 /* Set P to the first jump insn that goes around "x = a;". */ 827 for (p = temp; nuses && p; p = prev_nonnote_insn (p)) 828 { 829 if (GET_CODE (p) == JUMP_INSN) 830 { 831 if (condjump_p (p) && ! simplejump_p (p) 832 && JUMP_LABEL (p) == target) 833 { 834 nuses--; 835 if (nuses == 0) 836 break; 837 } 838 else 839 break; 840 } 841 else if (GET_CODE (p) == CALL_INSN) 842 break; 843 } 844 845#ifdef HAVE_cc0 846 /* We cannot insert anything between a set of cc and its use 847 so if P uses cc0, we must back up to the previous insn. */ 848 q = prev_nonnote_insn (p); 849 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i' 850 && sets_cc0_p (PATTERN (q))) 851 p = q; 852#endif 853 854 if (p) 855 p = PREV_INSN (p); 856 857 /* If we found all the uses and there was no data conflict, we 858 can move the assignment unless we can branch into the middle 859 from somewhere. */ 860 if (nuses == 0 && p 861 && no_labels_between_p (p, insn) 862 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3)) 863 && ! reg_set_between_p (temp1, p, temp3) 864 && (GET_CODE (SET_SRC (temp4)) == CONST_INT 865 || ! modified_between_p (SET_SRC (temp4), p, temp2))) 866 { 867 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2); 868 delete_insn (temp2); 869 870 /* Set NEXT to an insn that we know won't go away. */ 871 next = next_active_insn (insn); 872 873 /* Delete the jump around the set. Note that we must do 874 this before we redirect the test jumps so that it won't 875 delete the code immediately following the assignment 876 we moved (which might be a jump). */ 877 878 delete_insn (insn); 879 880 /* We either have two consecutive labels or a jump to 881 a jump, so adjust all the JUMP_INSNs to branch to where 882 INSN branches to. */ 883 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p)) 884 if (GET_CODE (p) == JUMP_INSN) 885 redirect_jump (p, target); 886 887 changed = 1; 888 continue; 889 } 890 } 891 892 /* Simplify if (...) { x = a; goto l; } x = b; by converting it 893 to x = a; if (...) goto l; x = b; 894 if A is sufficiently simple, the test doesn't involve X, 895 and nothing in the test modifies A or X. 896 897 If we have small register classes, we also can't do this if X 898 is a hard register. 899 900 If the "x = a;" insn has any REG_NOTES, we don't do this because 901 of the possibility that we are running after CSE and there is a 902 REG_EQUAL note that is only valid if the branch has already been 903 taken. If we move the insn with the REG_EQUAL note, we may 904 fold the comparison to always be false in a later CSE pass. 905 (We could also delete the REG_NOTES when moving the insn, but it 906 seems simpler to not move it.) An exception is that we can move 907 the insn if the only note is a REG_EQUAL or REG_EQUIV whose 908 value is the same as "a". 909 910 INSN is the goto. 911 912 We set: 913 914 TEMP to the jump insn preceding "x = a;" 915 TEMP1 to X 916 TEMP2 to the insn that sets "x = b;" 917 TEMP3 to the insn that sets "x = a;" 918 TEMP4 to the set of "x = a"; */ 919 920 if (this_is_simplejump 921 && (temp2 = next_active_insn (insn)) != 0 922 && GET_CODE (temp2) == INSN 923 && (temp4 = single_set (temp2)) != 0 924 && GET_CODE (temp1 = SET_DEST (temp4)) == REG 925 && (! SMALL_REGISTER_CLASSES 926 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER) 927 && (temp3 = prev_active_insn (insn)) != 0 928 && GET_CODE (temp3) == INSN 929 && (temp4 = single_set (temp3)) != 0 930 && rtx_equal_p (SET_DEST (temp4), temp1) 931 && ! side_effects_p (SET_SRC (temp4)) 932 && ! may_trap_p (SET_SRC (temp4)) 933 && (REG_NOTES (temp3) == 0 934 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL 935 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV) 936 && XEXP (REG_NOTES (temp3), 1) == 0 937 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0), 938 SET_SRC (temp4)))) 939 && (temp = prev_active_insn (temp3)) != 0 940 && condjump_p (temp) && ! simplejump_p (temp) 941 /* TEMP must skip over the "x = a;" insn */ 942 && prev_real_insn (JUMP_LABEL (temp)) == insn 943 && no_labels_between_p (temp, insn)) 944 { 945 rtx prev_label = JUMP_LABEL (temp); 946 rtx insert_after = prev_nonnote_insn (temp); 947 948#ifdef HAVE_cc0 949 /* We cannot insert anything between a set of cc and its use. */ 950 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i' 951 && sets_cc0_p (PATTERN (insert_after))) 952 insert_after = prev_nonnote_insn (insert_after); 953#endif 954 ++LABEL_NUSES (prev_label); 955 956 if (insert_after 957 && no_labels_between_p (insert_after, temp) 958 && ! reg_referenced_between_p (temp1, insert_after, temp3) 959 && ! reg_referenced_between_p (temp1, temp3, 960 NEXT_INSN (temp2)) 961 && ! reg_set_between_p (temp1, insert_after, temp) 962 && ! modified_between_p (SET_SRC (temp4), insert_after, temp) 963 && invert_jump (temp, JUMP_LABEL (insn))) 964 { 965 emit_insn_after_with_line_notes (PATTERN (temp3), 966 insert_after, temp3); 967 delete_insn (temp3); 968 delete_insn (insn); 969 /* Set NEXT to an insn that we know won't go away. */ 970 next = temp2; 971 changed = 1; 972 } 973 if (prev_label && --LABEL_NUSES (prev_label) == 0) 974 delete_insn (prev_label); 975 if (changed) 976 continue; 977 } 978 979#ifndef HAVE_cc0 980 /* If we have if (...) x = exp; and branches are expensive, 981 EXP is a single insn, does not have any side effects, cannot 982 trap, and is not too costly, convert this to 983 t = exp; if (...) x = t; 984 985 Don't do this when we have CC0 because it is unlikely to help 986 and we'd need to worry about where to place the new insn and 987 the potential for conflicts. We also can't do this when we have 988 notes on the insn for the same reason as above. 989 990 We set: 991 992 TEMP to the "x = exp;" insn. 993 TEMP1 to the single set in the "x = exp;" insn. 994 TEMP2 to "x". */ 995 996 if (! reload_completed 997 && this_is_condjump && ! this_is_simplejump 998 && BRANCH_COST >= 3 999 && (temp = next_nonnote_insn (insn)) != 0 1000 && GET_CODE (temp) == INSN 1001 && REG_NOTES (temp) == 0 1002 && (reallabelprev == temp 1003 || ((temp2 = next_active_insn (temp)) != 0 1004 && simplejump_p (temp2) 1005 && JUMP_LABEL (temp2) == JUMP_LABEL (insn))) 1006 && (temp1 = single_set (temp)) != 0 1007 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG) 1008 && (! SMALL_REGISTER_CLASSES 1009 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER) 1010 && GET_CODE (SET_SRC (temp1)) != REG 1011 && GET_CODE (SET_SRC (temp1)) != SUBREG 1012 && GET_CODE (SET_SRC (temp1)) != CONST_INT 1013 && ! side_effects_p (SET_SRC (temp1)) 1014 && ! may_trap_p (SET_SRC (temp1)) 1015 && rtx_cost (SET_SRC (temp1), SET) < 10) 1016 { 1017 rtx new = gen_reg_rtx (GET_MODE (temp2)); 1018 1019 if ((temp3 = find_insert_position (insn, temp)) 1020 && validate_change (temp, &SET_DEST (temp1), new, 0)) 1021 { 1022 next = emit_insn_after (gen_move_insn (temp2, new), insn); 1023 emit_insn_after_with_line_notes (PATTERN (temp), 1024 PREV_INSN (temp3), temp); 1025 delete_insn (temp); 1026 reallabelprev = prev_active_insn (JUMP_LABEL (insn)); 1027 1028 if (after_regscan) 1029 { 1030 reg_scan_update (temp3, NEXT_INSN (next), old_max_reg); 1031 old_max_reg = max_reg_num (); 1032 } 1033 } 1034 } 1035 1036 /* Similarly, if it takes two insns to compute EXP but they 1037 have the same destination. Here TEMP3 will be the second 1038 insn and TEMP4 the SET from that insn. */ 1039 1040 if (! reload_completed 1041 && this_is_condjump && ! this_is_simplejump 1042 && BRANCH_COST >= 4 1043 && (temp = next_nonnote_insn (insn)) != 0 1044 && GET_CODE (temp) == INSN 1045 && REG_NOTES (temp) == 0 1046 && (temp3 = next_nonnote_insn (temp)) != 0 1047 && GET_CODE (temp3) == INSN 1048 && REG_NOTES (temp3) == 0 1049 && (reallabelprev == temp3 1050 || ((temp2 = next_active_insn (temp3)) != 0 1051 && simplejump_p (temp2) 1052 && JUMP_LABEL (temp2) == JUMP_LABEL (insn))) 1053 && (temp1 = single_set (temp)) != 0 1054 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG) 1055 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT 1056 && (! SMALL_REGISTER_CLASSES 1057 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER) 1058 && ! side_effects_p (SET_SRC (temp1)) 1059 && ! may_trap_p (SET_SRC (temp1)) 1060 && rtx_cost (SET_SRC (temp1), SET) < 10 1061 && (temp4 = single_set (temp3)) != 0 1062 && rtx_equal_p (SET_DEST (temp4), temp2) 1063 && ! side_effects_p (SET_SRC (temp4)) 1064 && ! may_trap_p (SET_SRC (temp4)) 1065 && rtx_cost (SET_SRC (temp4), SET) < 10) 1066 { 1067 rtx new = gen_reg_rtx (GET_MODE (temp2)); 1068 1069 if ((temp5 = find_insert_position (insn, temp)) 1070 && (temp6 = find_insert_position (insn, temp3)) 1071 && validate_change (temp, &SET_DEST (temp1), new, 0)) 1072 { 1073 /* Use the earliest of temp5 and temp6. */ 1074 if (temp5 != insn) 1075 temp6 = temp5; 1076 next = emit_insn_after (gen_move_insn (temp2, new), insn); 1077 emit_insn_after_with_line_notes (PATTERN (temp), 1078 PREV_INSN (temp6), temp); 1079 emit_insn_after_with_line_notes 1080 (replace_rtx (PATTERN (temp3), temp2, new), 1081 PREV_INSN (temp6), temp3); 1082 delete_insn (temp); 1083 delete_insn (temp3); 1084 reallabelprev = prev_active_insn (JUMP_LABEL (insn)); 1085 1086 if (after_regscan) 1087 { 1088 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg); 1089 old_max_reg = max_reg_num (); 1090 } 1091 } 1092 } 1093 1094 /* Finally, handle the case where two insns are used to 1095 compute EXP but a temporary register is used. Here we must 1096 ensure that the temporary register is not used anywhere else. */ 1097 1098 if (! reload_completed 1099 && after_regscan 1100 && this_is_condjump && ! this_is_simplejump 1101 && BRANCH_COST >= 4 1102 && (temp = next_nonnote_insn (insn)) != 0 1103 && GET_CODE (temp) == INSN 1104 && REG_NOTES (temp) == 0 1105 && (temp3 = next_nonnote_insn (temp)) != 0 1106 && GET_CODE (temp3) == INSN 1107 && REG_NOTES (temp3) == 0 1108 && (reallabelprev == temp3 1109 || ((temp2 = next_active_insn (temp3)) != 0 1110 && simplejump_p (temp2) 1111 && JUMP_LABEL (temp2) == JUMP_LABEL (insn))) 1112 && (temp1 = single_set (temp)) != 0 1113 && (temp5 = SET_DEST (temp1), 1114 (GET_CODE (temp5) == REG 1115 || (GET_CODE (temp5) == SUBREG 1116 && (temp5 = SUBREG_REG (temp5), 1117 GET_CODE (temp5) == REG)))) 1118 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER 1119 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp) 1120 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3) 1121 && ! side_effects_p (SET_SRC (temp1)) 1122 && ! may_trap_p (SET_SRC (temp1)) 1123 && rtx_cost (SET_SRC (temp1), SET) < 10 1124 && (temp4 = single_set (temp3)) != 0 1125 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG) 1126 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT 1127 && (! SMALL_REGISTER_CLASSES 1128 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER) 1129 && rtx_equal_p (SET_DEST (temp4), temp2) 1130 && ! side_effects_p (SET_SRC (temp4)) 1131 && ! may_trap_p (SET_SRC (temp4)) 1132 && rtx_cost (SET_SRC (temp4), SET) < 10) 1133 { 1134 rtx new = gen_reg_rtx (GET_MODE (temp2)); 1135 1136 if ((temp5 = find_insert_position (insn, temp)) 1137 && (temp6 = find_insert_position (insn, temp3)) 1138 && validate_change (temp3, &SET_DEST (temp4), new, 0)) 1139 { 1140 /* Use the earliest of temp5 and temp6. */ 1141 if (temp5 != insn) 1142 temp6 = temp5; 1143 next = emit_insn_after (gen_move_insn (temp2, new), insn); 1144 emit_insn_after_with_line_notes (PATTERN (temp), 1145 PREV_INSN (temp6), temp); 1146 emit_insn_after_with_line_notes (PATTERN (temp3), 1147 PREV_INSN (temp6), temp3); 1148 delete_insn (temp); 1149 delete_insn (temp3); 1150 reallabelprev = prev_active_insn (JUMP_LABEL (insn)); 1151 1152 if (after_regscan) 1153 { 1154 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg); 1155 old_max_reg = max_reg_num (); 1156 } 1157 } 1158 } 1159#endif /* HAVE_cc0 */ 1160 1161 /* Try to use a conditional move (if the target has them), or a 1162 store-flag insn. The general case is: 1163 1164 1) x = a; if (...) x = b; and 1165 2) if (...) x = b; 1166 1167 If the jump would be faster, the machine should not have defined 1168 the movcc or scc insns!. These cases are often made by the 1169 previous optimization. 1170 1171 The second case is treated as x = x; if (...) x = b;. 1172 1173 INSN here is the jump around the store. We set: 1174 1175 TEMP to the "x = b;" insn. 1176 TEMP1 to X. 1177 TEMP2 to B. 1178 TEMP3 to A (X in the second case). 1179 TEMP4 to the condition being tested. 1180 TEMP5 to the earliest insn used to find the condition. */ 1181 1182 if (/* We can't do this after reload has completed. */ 1183 ! reload_completed 1184 && this_is_condjump && ! this_is_simplejump 1185 /* Set TEMP to the "x = b;" insn. */ 1186 && (temp = next_nonnote_insn (insn)) != 0 1187 && GET_CODE (temp) == INSN 1188 && GET_CODE (PATTERN (temp)) == SET 1189 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG 1190 && (! SMALL_REGISTER_CLASSES 1191 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER) 1192 && ! side_effects_p (temp2 = SET_SRC (PATTERN (temp))) 1193 && ! may_trap_p (temp2) 1194 /* Allow either form, but prefer the former if both apply. 1195 There is no point in using the old value of TEMP1 if 1196 it is a register, since cse will alias them. It can 1197 lose if the old value were a hard register since CSE 1198 won't replace hard registers. Avoid using TEMP3 if 1199 small register classes and it is a hard register. */ 1200 && (((temp3 = reg_set_last (temp1, insn)) != 0 1201 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG 1202 && REGNO (temp3) < FIRST_PSEUDO_REGISTER)) 1203 /* Make the latter case look like x = x; if (...) x = b; */ 1204 || (temp3 = temp1, 1)) 1205 /* INSN must either branch to the insn after TEMP or the insn 1206 after TEMP must branch to the same place as INSN. */ 1207 && (reallabelprev == temp 1208 || ((temp4 = next_active_insn (temp)) != 0 1209 && simplejump_p (temp4) 1210 && JUMP_LABEL (temp4) == JUMP_LABEL (insn))) 1211 && (temp4 = get_condition (insn, &temp5)) != 0 1212 /* We must be comparing objects whose modes imply the size. 1213 We could handle BLKmode if (1) emit_store_flag could 1214 and (2) we could find the size reliably. */ 1215 && GET_MODE (XEXP (temp4, 0)) != BLKmode 1216 /* Even if branches are cheap, the store_flag optimization 1217 can win when the operation to be performed can be 1218 expressed directly. */ 1219#ifdef HAVE_cc0 1220 /* If the previous insn sets CC0 and something else, we can't 1221 do this since we are going to delete that insn. */ 1222 1223 && ! ((temp6 = prev_nonnote_insn (insn)) != 0 1224 && GET_CODE (temp6) == INSN 1225 && (sets_cc0_p (PATTERN (temp6)) == -1 1226 || (sets_cc0_p (PATTERN (temp6)) == 1 1227 && FIND_REG_INC_NOTE (temp6, NULL_RTX)))) 1228#endif 1229 ) 1230 { 1231#ifdef HAVE_conditional_move 1232 /* First try a conditional move. */ 1233 { 1234 enum rtx_code code = GET_CODE (temp4); 1235 rtx var = temp1; 1236 rtx cond0, cond1, aval, bval; 1237 rtx target; 1238 1239 /* Copy the compared variables into cond0 and cond1, so that 1240 any side effects performed in or after the old comparison, 1241 will not affect our compare which will come later. */ 1242 /* ??? Is it possible to just use the comparison in the jump 1243 insn? After all, we're going to delete it. We'd have 1244 to modify emit_conditional_move to take a comparison rtx 1245 instead or write a new function. */ 1246 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0))); 1247 /* We want the target to be able to simplify comparisons with 1248 zero (and maybe other constants as well), so don't create 1249 pseudos for them. There's no need to either. */ 1250 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT 1251 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE) 1252 cond1 = XEXP (temp4, 1); 1253 else 1254 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1))); 1255 1256 aval = temp3; 1257 bval = temp2; 1258 1259 start_sequence (); 1260 target = emit_conditional_move (var, code, 1261 cond0, cond1, VOIDmode, 1262 aval, bval, GET_MODE (var), 1263 (code == LTU || code == GEU 1264 || code == LEU || code == GTU)); 1265 1266 if (target) 1267 { 1268 rtx seq1,seq2,last; 1269 1270 /* Save the conditional move sequence but don't emit it 1271 yet. On some machines, like the alpha, it is possible 1272 that temp5 == insn, so next generate the sequence that 1273 saves the compared values and then emit both 1274 sequences ensuring seq1 occurs before seq2. */ 1275 seq2 = get_insns (); 1276 end_sequence (); 1277 1278 /* Now that we can't fail, generate the copy insns that 1279 preserve the compared values. */ 1280 start_sequence (); 1281 emit_move_insn (cond0, XEXP (temp4, 0)); 1282 if (cond1 != XEXP (temp4, 1)) 1283 emit_move_insn (cond1, XEXP (temp4, 1)); 1284 seq1 = get_insns (); 1285 end_sequence (); 1286 1287 emit_insns_before (seq1, temp5); 1288 /* Insert conditional move after insn, to be sure that 1289 the jump and a possible compare won't be separated */ 1290 last = emit_insns_after (seq2, insn); 1291 1292 /* ??? We can also delete the insn that sets X to A. 1293 Flow will do it too though. */ 1294 delete_insn (temp); 1295 next = NEXT_INSN (insn); 1296 delete_jump (insn); 1297 1298 if (after_regscan) 1299 { 1300 reg_scan_update (seq1, NEXT_INSN (last), old_max_reg); 1301 old_max_reg = max_reg_num (); 1302 } 1303 1304 changed = 1; 1305 continue; 1306 } 1307 else 1308 end_sequence (); 1309 } 1310#endif 1311 1312 /* That didn't work, try a store-flag insn. 1313 1314 We further divide the cases into: 1315 1316 1) x = a; if (...) x = b; and either A or B is zero, 1317 2) if (...) x = 0; and jumps are expensive, 1318 3) x = a; if (...) x = b; and A and B are constants where all 1319 the set bits in A are also set in B and jumps are expensive, 1320 4) x = a; if (...) x = b; and A and B non-zero, and jumps are 1321 more expensive, and 1322 5) if (...) x = b; if jumps are even more expensive. */ 1323 1324 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT 1325 && ((GET_CODE (temp3) == CONST_INT) 1326 /* Make the latter case look like 1327 x = x; if (...) x = 0; */ 1328 || (temp3 = temp1, 1329 ((BRANCH_COST >= 2 1330 && temp2 == const0_rtx) 1331 || BRANCH_COST >= 3))) 1332 /* If B is zero, OK; if A is zero, can only do (1) if we 1333 can reverse the condition. See if (3) applies possibly 1334 by reversing the condition. Prefer reversing to (4) when 1335 branches are very expensive. */ 1336 && (((BRANCH_COST >= 2 1337 || STORE_FLAG_VALUE == -1 1338 || (STORE_FLAG_VALUE == 1 1339 /* Check that the mask is a power of two, 1340 so that it can probably be generated 1341 with a shift. */ 1342 && GET_CODE (temp3) == CONST_INT 1343 && exact_log2 (INTVAL (temp3)) >= 0)) 1344 && (reversep = 0, temp2 == const0_rtx)) 1345 || ((BRANCH_COST >= 2 1346 || STORE_FLAG_VALUE == -1 1347 || (STORE_FLAG_VALUE == 1 1348 && GET_CODE (temp2) == CONST_INT 1349 && exact_log2 (INTVAL (temp2)) >= 0)) 1350 && temp3 == const0_rtx 1351 && (reversep = can_reverse_comparison_p (temp4, insn))) 1352 || (BRANCH_COST >= 2 1353 && GET_CODE (temp2) == CONST_INT 1354 && GET_CODE (temp3) == CONST_INT 1355 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2) 1356 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3) 1357 && (reversep = can_reverse_comparison_p (temp4, 1358 insn))))) 1359 || BRANCH_COST >= 3) 1360 ) 1361 { 1362 enum rtx_code code = GET_CODE (temp4); 1363 rtx uval, cval, var = temp1; 1364 int normalizep; 1365 rtx target; 1366 1367 /* If necessary, reverse the condition. */ 1368 if (reversep) 1369 code = reverse_condition (code), uval = temp2, cval = temp3; 1370 else 1371 uval = temp3, cval = temp2; 1372 1373 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL 1374 is the constant 1, it is best to just compute the result 1375 directly. If UVAL is constant and STORE_FLAG_VALUE 1376 includes all of its bits, it is best to compute the flag 1377 value unnormalized and `and' it with UVAL. Otherwise, 1378 normalize to -1 and `and' with UVAL. */ 1379 normalizep = (cval != const0_rtx ? -1 1380 : (uval == const1_rtx ? 1 1381 : (GET_CODE (uval) == CONST_INT 1382 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0) 1383 ? 0 : -1)); 1384 1385 /* We will be putting the store-flag insn immediately in 1386 front of the comparison that was originally being done, 1387 so we know all the variables in TEMP4 will be valid. 1388 However, this might be in front of the assignment of 1389 A to VAR. If it is, it would clobber the store-flag 1390 we will be emitting. 1391 1392 Therefore, emit into a temporary which will be copied to 1393 VAR immediately after TEMP. */ 1394 1395 start_sequence (); 1396 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code, 1397 XEXP (temp4, 0), XEXP (temp4, 1), 1398 VOIDmode, 1399 (code == LTU || code == LEU 1400 || code == GEU || code == GTU), 1401 normalizep); 1402 if (target) 1403 { 1404 rtx seq; 1405 rtx before = insn; 1406 1407 seq = get_insns (); 1408 end_sequence (); 1409 1410 /* Put the store-flag insns in front of the first insn 1411 used to compute the condition to ensure that we 1412 use the same values of them as the current 1413 comparison. However, the remainder of the insns we 1414 generate will be placed directly in front of the 1415 jump insn, in case any of the pseudos we use 1416 are modified earlier. */ 1417 1418 emit_insns_before (seq, temp5); 1419 1420 start_sequence (); 1421 1422 /* Both CVAL and UVAL are non-zero. */ 1423 if (cval != const0_rtx && uval != const0_rtx) 1424 { 1425 rtx tem1, tem2; 1426 1427 tem1 = expand_and (uval, target, NULL_RTX); 1428 if (GET_CODE (cval) == CONST_INT 1429 && GET_CODE (uval) == CONST_INT 1430 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval)) 1431 tem2 = cval; 1432 else 1433 { 1434 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab, 1435 target, NULL_RTX, 0); 1436 tem2 = expand_and (cval, tem2, 1437 (GET_CODE (tem2) == REG 1438 ? tem2 : 0)); 1439 } 1440 1441 /* If we usually make new pseudos, do so here. This 1442 turns out to help machines that have conditional 1443 move insns. */ 1444 /* ??? Conditional moves have already been handled. 1445 This may be obsolete. */ 1446 1447 if (flag_expensive_optimizations) 1448 target = 0; 1449 1450 target = expand_binop (GET_MODE (var), ior_optab, 1451 tem1, tem2, target, 1452 1, OPTAB_WIDEN); 1453 } 1454 else if (normalizep != 1) 1455 { 1456 /* We know that either CVAL or UVAL is zero. If 1457 UVAL is zero, negate TARGET and `and' with CVAL. 1458 Otherwise, `and' with UVAL. */ 1459 if (uval == const0_rtx) 1460 { 1461 target = expand_unop (GET_MODE (var), one_cmpl_optab, 1462 target, NULL_RTX, 0); 1463 uval = cval; 1464 } 1465 1466 target = expand_and (uval, target, 1467 (GET_CODE (target) == REG 1468 && ! preserve_subexpressions_p () 1469 ? target : NULL_RTX)); 1470 } 1471 1472 emit_move_insn (var, target); 1473 seq = get_insns (); 1474 end_sequence (); 1475#ifdef HAVE_cc0 1476 /* If INSN uses CC0, we must not separate it from the 1477 insn that sets cc0. */ 1478 if (reg_mentioned_p (cc0_rtx, PATTERN (before))) 1479 before = prev_nonnote_insn (before); 1480#endif 1481 emit_insns_before (seq, before); 1482 1483 delete_insn (temp); 1484 next = NEXT_INSN (insn); 1485 delete_jump (insn); 1486 1487 if (after_regscan) 1488 { 1489 reg_scan_update (seq, NEXT_INSN (next), old_max_reg); 1490 old_max_reg = max_reg_num (); 1491 } 1492 1493 changed = 1; 1494 continue; 1495 } 1496 else 1497 end_sequence (); 1498 } 1499 } 1500 1501 /* If branches are expensive, convert 1502 if (foo) bar++; to bar += (foo != 0); 1503 and similarly for "bar--;" 1504 1505 INSN is the conditional branch around the arithmetic. We set: 1506 1507 TEMP is the arithmetic insn. 1508 TEMP1 is the SET doing the arithmetic. 1509 TEMP2 is the operand being incremented or decremented. 1510 TEMP3 to the condition being tested. 1511 TEMP4 to the earliest insn used to find the condition. */ 1512 1513 if ((BRANCH_COST >= 2 1514#ifdef HAVE_incscc 1515 || HAVE_incscc 1516#endif 1517#ifdef HAVE_decscc 1518 || HAVE_decscc 1519#endif 1520 ) 1521 && ! reload_completed 1522 && this_is_condjump && ! this_is_simplejump 1523 && (temp = next_nonnote_insn (insn)) != 0 1524 && (temp1 = single_set (temp)) != 0 1525 && (temp2 = SET_DEST (temp1), 1526 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT) 1527 && GET_CODE (SET_SRC (temp1)) == PLUS 1528 && (XEXP (SET_SRC (temp1), 1) == const1_rtx 1529 || XEXP (SET_SRC (temp1), 1) == constm1_rtx) 1530 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0)) 1531 && ! side_effects_p (temp2) 1532 && ! may_trap_p (temp2) 1533 /* INSN must either branch to the insn after TEMP or the insn 1534 after TEMP must branch to the same place as INSN. */ 1535 && (reallabelprev == temp 1536 || ((temp3 = next_active_insn (temp)) != 0 1537 && simplejump_p (temp3) 1538 && JUMP_LABEL (temp3) == JUMP_LABEL (insn))) 1539 && (temp3 = get_condition (insn, &temp4)) != 0 1540 /* We must be comparing objects whose modes imply the size. 1541 We could handle BLKmode if (1) emit_store_flag could 1542 and (2) we could find the size reliably. */ 1543 && GET_MODE (XEXP (temp3, 0)) != BLKmode 1544 && can_reverse_comparison_p (temp3, insn)) 1545 { 1546 rtx temp6, target = 0, seq, init_insn = 0, init = temp2; 1547 enum rtx_code code = reverse_condition (GET_CODE (temp3)); 1548 1549 start_sequence (); 1550 1551 /* It must be the case that TEMP2 is not modified in the range 1552 [TEMP4, INSN). The one exception we make is if the insn 1553 before INSN sets TEMP2 to something which is also unchanged 1554 in that range. In that case, we can move the initialization 1555 into our sequence. */ 1556 1557 if ((temp5 = prev_active_insn (insn)) != 0 1558 && no_labels_between_p (temp5, insn) 1559 && GET_CODE (temp5) == INSN 1560 && (temp6 = single_set (temp5)) != 0 1561 && rtx_equal_p (temp2, SET_DEST (temp6)) 1562 && (CONSTANT_P (SET_SRC (temp6)) 1563 || GET_CODE (SET_SRC (temp6)) == REG 1564 || GET_CODE (SET_SRC (temp6)) == SUBREG)) 1565 { 1566 emit_insn (PATTERN (temp5)); 1567 init_insn = temp5; 1568 init = SET_SRC (temp6); 1569 } 1570 1571 if (CONSTANT_P (init) 1572 || ! reg_set_between_p (init, PREV_INSN (temp4), insn)) 1573 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code, 1574 XEXP (temp3, 0), XEXP (temp3, 1), 1575 VOIDmode, 1576 (code == LTU || code == LEU 1577 || code == GTU || code == GEU), 1); 1578 1579 /* If we can do the store-flag, do the addition or 1580 subtraction. */ 1581 1582 if (target) 1583 target = expand_binop (GET_MODE (temp2), 1584 (XEXP (SET_SRC (temp1), 1) == const1_rtx 1585 ? add_optab : sub_optab), 1586 temp2, target, temp2, 0, OPTAB_WIDEN); 1587 1588 if (target != 0) 1589 { 1590 /* Put the result back in temp2 in case it isn't already. 1591 Then replace the jump, possible a CC0-setting insn in 1592 front of the jump, and TEMP, with the sequence we have 1593 made. */ 1594 1595 if (target != temp2) 1596 emit_move_insn (temp2, target); 1597 1598 seq = get_insns (); 1599 end_sequence (); 1600 1601 emit_insns_before (seq, temp4); 1602 delete_insn (temp); 1603 1604 if (init_insn) 1605 delete_insn (init_insn); 1606 1607 next = NEXT_INSN (insn); 1608#ifdef HAVE_cc0 1609 delete_insn (prev_nonnote_insn (insn)); 1610#endif 1611 delete_insn (insn); 1612 1613 if (after_regscan) 1614 { 1615 reg_scan_update (seq, NEXT_INSN (next), old_max_reg); 1616 old_max_reg = max_reg_num (); 1617 } 1618 1619 changed = 1; 1620 continue; 1621 } 1622 else 1623 end_sequence (); 1624 } 1625 1626 /* Simplify if (...) x = 1; else {...} if (x) ... 1627 We recognize this case scanning backwards as well. 1628 1629 TEMP is the assignment to x; 1630 TEMP1 is the label at the head of the second if. */ 1631 /* ?? This should call get_condition to find the values being 1632 compared, instead of looking for a COMPARE insn when HAVE_cc0 1633 is not defined. This would allow it to work on the m88k. */ 1634 /* ?? This optimization is only safe before cse is run if HAVE_cc0 1635 is not defined and the condition is tested by a separate compare 1636 insn. This is because the code below assumes that the result 1637 of the compare dies in the following branch. 1638 1639 Not only that, but there might be other insns between the 1640 compare and branch whose results are live. Those insns need 1641 to be executed. 1642 1643 A way to fix this is to move the insns at JUMP_LABEL (insn) 1644 to before INSN. If we are running before flow, they will 1645 be deleted if they aren't needed. But this doesn't work 1646 well after flow. 1647 1648 This is really a special-case of jump threading, anyway. The 1649 right thing to do is to replace this and jump threading with 1650 much simpler code in cse. 1651 1652 This code has been turned off in the non-cc0 case in the 1653 meantime. */ 1654 1655#ifdef HAVE_cc0 1656 else if (this_is_simplejump 1657 /* Safe to skip USE and CLOBBER insns here 1658 since they will not be deleted. */ 1659 && (temp = prev_active_insn (insn)) 1660 && no_labels_between_p (temp, insn) 1661 && GET_CODE (temp) == INSN 1662 && GET_CODE (PATTERN (temp)) == SET 1663 && GET_CODE (SET_DEST (PATTERN (temp))) == REG 1664 && CONSTANT_P (SET_SRC (PATTERN (temp))) 1665 && (temp1 = next_active_insn (JUMP_LABEL (insn))) 1666 /* If we find that the next value tested is `x' 1667 (TEMP1 is the insn where this happens), win. */ 1668 && GET_CODE (temp1) == INSN 1669 && GET_CODE (PATTERN (temp1)) == SET 1670#ifdef HAVE_cc0 1671 /* Does temp1 `tst' the value of x? */ 1672 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp)) 1673 && SET_DEST (PATTERN (temp1)) == cc0_rtx 1674 && (temp1 = next_nonnote_insn (temp1)) 1675#else 1676 /* Does temp1 compare the value of x against zero? */ 1677 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE 1678 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx 1679 && (XEXP (SET_SRC (PATTERN (temp1)), 0) 1680 == SET_DEST (PATTERN (temp))) 1681 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG 1682 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1)) 1683#endif 1684 && condjump_p (temp1)) 1685 { 1686 /* Get the if_then_else from the condjump. */ 1687 rtx choice = SET_SRC (PATTERN (temp1)); 1688 if (GET_CODE (choice) == IF_THEN_ELSE) 1689 { 1690 enum rtx_code code = GET_CODE (XEXP (choice, 0)); 1691 rtx val = SET_SRC (PATTERN (temp)); 1692 rtx cond 1693 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))), 1694 val, const0_rtx); 1695 rtx ultimate; 1696 1697 if (cond == const_true_rtx) 1698 ultimate = XEXP (choice, 1); 1699 else if (cond == const0_rtx) 1700 ultimate = XEXP (choice, 2); 1701 else 1702 ultimate = 0; 1703 1704 if (ultimate == pc_rtx) 1705 ultimate = get_label_after (temp1); 1706 else if (ultimate && GET_CODE (ultimate) != RETURN) 1707 ultimate = XEXP (ultimate, 0); 1708 1709 if (ultimate && JUMP_LABEL(insn) != ultimate) 1710 changed |= redirect_jump (insn, ultimate); 1711 } 1712 } 1713#endif 1714 1715#if 0 1716 /* @@ This needs a bit of work before it will be right. 1717 1718 Any type of comparison can be accepted for the first and 1719 second compare. When rewriting the first jump, we must 1720 compute the what conditions can reach label3, and use the 1721 appropriate code. We can not simply reverse/swap the code 1722 of the first jump. In some cases, the second jump must be 1723 rewritten also. 1724 1725 For example, 1726 < == converts to > == 1727 < != converts to == > 1728 etc. 1729 1730 If the code is written to only accept an '==' test for the second 1731 compare, then all that needs to be done is to swap the condition 1732 of the first branch. 1733 1734 It is questionable whether we want this optimization anyways, 1735 since if the user wrote code like this because he/she knew that 1736 the jump to label1 is taken most of the time, then rewriting 1737 this gives slower code. */ 1738 /* @@ This should call get_condition to find the values being 1739 compared, instead of looking for a COMPARE insn when HAVE_cc0 1740 is not defined. This would allow it to work on the m88k. */ 1741 /* @@ This optimization is only safe before cse is run if HAVE_cc0 1742 is not defined and the condition is tested by a separate compare 1743 insn. This is because the code below assumes that the result 1744 of the compare dies in the following branch. */ 1745 1746 /* Simplify test a ~= b 1747 condjump label1; 1748 test a == b 1749 condjump label2; 1750 jump label3; 1751 label1: 1752 1753 rewriting as 1754 test a ~~= b 1755 condjump label3 1756 test a == b 1757 condjump label2 1758 label1: 1759 1760 where ~= is an inequality, e.g. >, and ~~= is the swapped 1761 inequality, e.g. <. 1762 1763 We recognize this case scanning backwards. 1764 1765 TEMP is the conditional jump to `label2'; 1766 TEMP1 is the test for `a == b'; 1767 TEMP2 is the conditional jump to `label1'; 1768 TEMP3 is the test for `a ~= b'. */ 1769 else if (this_is_simplejump 1770 && (temp = prev_active_insn (insn)) 1771 && no_labels_between_p (temp, insn) 1772 && condjump_p (temp) 1773 && (temp1 = prev_active_insn (temp)) 1774 && no_labels_between_p (temp1, temp) 1775 && GET_CODE (temp1) == INSN 1776 && GET_CODE (PATTERN (temp1)) == SET 1777#ifdef HAVE_cc0 1778 && sets_cc0_p (PATTERN (temp1)) == 1 1779#else 1780 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE 1781 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG 1782 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1)) 1783#endif 1784 && (temp2 = prev_active_insn (temp1)) 1785 && no_labels_between_p (temp2, temp1) 1786 && condjump_p (temp2) 1787 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn)) 1788 && (temp3 = prev_active_insn (temp2)) 1789 && no_labels_between_p (temp3, temp2) 1790 && GET_CODE (PATTERN (temp3)) == SET 1791 && rtx_equal_p (SET_DEST (PATTERN (temp3)), 1792 SET_DEST (PATTERN (temp1))) 1793 && rtx_equal_p (SET_SRC (PATTERN (temp1)), 1794 SET_SRC (PATTERN (temp3))) 1795 && ! inequality_comparisons_p (PATTERN (temp)) 1796 && inequality_comparisons_p (PATTERN (temp2))) 1797 { 1798 rtx fallthrough_label = JUMP_LABEL (temp2); 1799 1800 ++LABEL_NUSES (fallthrough_label); 1801 if (swap_jump (temp2, JUMP_LABEL (insn))) 1802 { 1803 delete_insn (insn); 1804 changed = 1; 1805 } 1806 1807 if (--LABEL_NUSES (fallthrough_label) == 0) 1808 delete_insn (fallthrough_label); 1809 } 1810#endif 1811 /* Simplify if (...) {... x = 1;} if (x) ... 1812 1813 We recognize this case backwards. 1814 1815 TEMP is the test of `x'; 1816 TEMP1 is the assignment to `x' at the end of the 1817 previous statement. */ 1818 /* @@ This should call get_condition to find the values being 1819 compared, instead of looking for a COMPARE insn when HAVE_cc0 1820 is not defined. This would allow it to work on the m88k. */ 1821 /* @@ This optimization is only safe before cse is run if HAVE_cc0 1822 is not defined and the condition is tested by a separate compare 1823 insn. This is because the code below assumes that the result 1824 of the compare dies in the following branch. */ 1825 1826 /* ??? This has to be turned off. The problem is that the 1827 unconditional jump might indirectly end up branching to the 1828 label between TEMP1 and TEMP. We can't detect this, in general, 1829 since it may become a jump to there after further optimizations. 1830 If that jump is done, it will be deleted, so we will retry 1831 this optimization in the next pass, thus an infinite loop. 1832 1833 The present code prevents this by putting the jump after the 1834 label, but this is not logically correct. */ 1835#if 0 1836 else if (this_is_condjump 1837 /* Safe to skip USE and CLOBBER insns here 1838 since they will not be deleted. */ 1839 && (temp = prev_active_insn (insn)) 1840 && no_labels_between_p (temp, insn) 1841 && GET_CODE (temp) == INSN 1842 && GET_CODE (PATTERN (temp)) == SET 1843#ifdef HAVE_cc0 1844 && sets_cc0_p (PATTERN (temp)) == 1 1845 && GET_CODE (SET_SRC (PATTERN (temp))) == REG 1846#else 1847 /* Temp must be a compare insn, we can not accept a register 1848 to register move here, since it may not be simply a 1849 tst insn. */ 1850 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE 1851 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx 1852 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG 1853 && GET_CODE (SET_DEST (PATTERN (temp))) == REG 1854 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp) 1855#endif 1856 /* May skip USE or CLOBBER insns here 1857 for checking for opportunity, since we 1858 take care of them later. */ 1859 && (temp1 = prev_active_insn (temp)) 1860 && GET_CODE (temp1) == INSN 1861 && GET_CODE (PATTERN (temp1)) == SET 1862#ifdef HAVE_cc0 1863 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1)) 1864#else 1865 && (XEXP (SET_SRC (PATTERN (temp)), 0) 1866 == SET_DEST (PATTERN (temp1))) 1867#endif 1868 && CONSTANT_P (SET_SRC (PATTERN (temp1))) 1869 /* If this isn't true, cse will do the job. */ 1870 && ! no_labels_between_p (temp1, temp)) 1871 { 1872 /* Get the if_then_else from the condjump. */ 1873 rtx choice = SET_SRC (PATTERN (insn)); 1874 if (GET_CODE (choice) == IF_THEN_ELSE 1875 && (GET_CODE (XEXP (choice, 0)) == EQ 1876 || GET_CODE (XEXP (choice, 0)) == NE)) 1877 { 1878 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE); 1879 rtx last_insn; 1880 rtx ultimate; 1881 rtx p; 1882 1883 /* Get the place that condjump will jump to 1884 if it is reached from here. */ 1885 if ((SET_SRC (PATTERN (temp1)) != const0_rtx) 1886 == want_nonzero) 1887 ultimate = XEXP (choice, 1); 1888 else 1889 ultimate = XEXP (choice, 2); 1890 /* Get it as a CODE_LABEL. */ 1891 if (ultimate == pc_rtx) 1892 ultimate = get_label_after (insn); 1893 else 1894 /* Get the label out of the LABEL_REF. */ 1895 ultimate = XEXP (ultimate, 0); 1896 1897 /* Insert the jump immediately before TEMP, specifically 1898 after the label that is between TEMP1 and TEMP. */ 1899 last_insn = PREV_INSN (temp); 1900 1901 /* If we would be branching to the next insn, the jump 1902 would immediately be deleted and the re-inserted in 1903 a subsequent pass over the code. So don't do anything 1904 in that case. */ 1905 if (next_active_insn (last_insn) 1906 != next_active_insn (ultimate)) 1907 { 1908 emit_barrier_after (last_insn); 1909 p = emit_jump_insn_after (gen_jump (ultimate), 1910 last_insn); 1911 JUMP_LABEL (p) = ultimate; 1912 ++LABEL_NUSES (ultimate); 1913 if (INSN_UID (ultimate) < max_jump_chain 1914 && INSN_CODE (p) < max_jump_chain) 1915 { 1916 jump_chain[INSN_UID (p)] 1917 = jump_chain[INSN_UID (ultimate)]; 1918 jump_chain[INSN_UID (ultimate)] = p; 1919 } 1920 changed = 1; 1921 continue; 1922 } 1923 } 1924 } 1925#endif 1926 /* Detect a conditional jump going to the same place 1927 as an immediately following unconditional jump. */ 1928 else if (this_is_condjump 1929 && (temp = next_active_insn (insn)) != 0 1930 && simplejump_p (temp) 1931 && (next_active_insn (JUMP_LABEL (insn)) 1932 == next_active_insn (JUMP_LABEL (temp)))) 1933 { 1934 rtx tem = temp; 1935 1936 /* ??? Optional. Disables some optimizations, but makes 1937 gcov output more accurate with -O. */ 1938 if (flag_test_coverage && !reload_completed) 1939 for (tem = insn; tem != temp; tem = NEXT_INSN (tem)) 1940 if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0) 1941 break; 1942 1943 if (tem == temp) 1944 { 1945 delete_jump (insn); 1946 changed = 1; 1947 continue; 1948 } 1949 } 1950#ifdef HAVE_trap 1951 /* Detect a conditional jump jumping over an unconditional trap. */ 1952 else if (HAVE_trap 1953 && this_is_condjump && ! this_is_simplejump 1954 && reallabelprev != 0 1955 && GET_CODE (reallabelprev) == INSN 1956 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF 1957 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx 1958 && prev_active_insn (reallabelprev) == insn 1959 && no_labels_between_p (insn, reallabelprev) 1960 && (temp2 = get_condition (insn, &temp4)) 1961 && can_reverse_comparison_p (temp2, insn)) 1962 { 1963 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)), 1964 XEXP (temp2, 0), XEXP (temp2, 1), 1965 TRAP_CODE (PATTERN (reallabelprev))); 1966 1967 if (new) 1968 { 1969 emit_insn_before (new, temp4); 1970 delete_insn (reallabelprev); 1971 delete_jump (insn); 1972 changed = 1; 1973 continue; 1974 } 1975 } 1976 /* Detect a jump jumping to an unconditional trap. */ 1977 else if (HAVE_trap && this_is_condjump 1978 && (temp = next_active_insn (JUMP_LABEL (insn))) 1979 && GET_CODE (temp) == INSN 1980 && GET_CODE (PATTERN (temp)) == TRAP_IF 1981 && (this_is_simplejump 1982 || (temp2 = get_condition (insn, &temp4)))) 1983 { 1984 rtx tc = TRAP_CONDITION (PATTERN (temp)); 1985 1986 if (tc == const_true_rtx 1987 || (! this_is_simplejump && rtx_equal_p (temp2, tc))) 1988 { 1989 rtx new; 1990 /* Replace an unconditional jump to a trap with a trap. */ 1991 if (this_is_simplejump) 1992 { 1993 emit_barrier_after (emit_insn_before (gen_trap (), insn)); 1994 delete_jump (insn); 1995 changed = 1; 1996 continue; 1997 } 1998 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0), 1999 XEXP (temp2, 1), 2000 TRAP_CODE (PATTERN (temp))); 2001 if (new) 2002 { 2003 emit_insn_before (new, temp4); 2004 delete_jump (insn); 2005 changed = 1; 2006 continue; 2007 } 2008 } 2009 /* If the trap condition and jump condition are mutually 2010 exclusive, redirect the jump to the following insn. */ 2011 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<' 2012 && ! this_is_simplejump 2013 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc) 2014 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0)) 2015 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1)) 2016 && redirect_jump (insn, get_label_after (temp))) 2017 { 2018 changed = 1; 2019 continue; 2020 } 2021 } 2022#endif 2023 2024 /* Detect a conditional jump jumping over an unconditional jump. */ 2025 2026 else if ((this_is_condjump || this_is_condjump_in_parallel) 2027 && ! this_is_simplejump 2028 && reallabelprev != 0 2029 && GET_CODE (reallabelprev) == JUMP_INSN 2030 && prev_active_insn (reallabelprev) == insn 2031 && no_labels_between_p (insn, reallabelprev) 2032 && simplejump_p (reallabelprev)) 2033 { 2034 /* When we invert the unconditional jump, we will be 2035 decrementing the usage count of its old label. 2036 Make sure that we don't delete it now because that 2037 might cause the following code to be deleted. */ 2038 rtx prev_uses = prev_nonnote_insn (reallabelprev); 2039 rtx prev_label = JUMP_LABEL (insn); 2040 2041 if (prev_label) 2042 ++LABEL_NUSES (prev_label); 2043 2044 if (invert_jump (insn, JUMP_LABEL (reallabelprev))) 2045 { 2046 /* It is very likely that if there are USE insns before 2047 this jump, they hold REG_DEAD notes. These REG_DEAD 2048 notes are no longer valid due to this optimization, 2049 and will cause the life-analysis that following passes 2050 (notably delayed-branch scheduling) to think that 2051 these registers are dead when they are not. 2052 2053 To prevent this trouble, we just remove the USE insns 2054 from the insn chain. */ 2055 2056 while (prev_uses && GET_CODE (prev_uses) == INSN 2057 && GET_CODE (PATTERN (prev_uses)) == USE) 2058 { 2059 rtx useless = prev_uses; 2060 prev_uses = prev_nonnote_insn (prev_uses); 2061 delete_insn (useless); 2062 } 2063 2064 delete_insn (reallabelprev); 2065 next = insn; 2066 changed = 1; 2067 } 2068 2069 /* We can now safely delete the label if it is unreferenced 2070 since the delete_insn above has deleted the BARRIER. */ 2071 if (prev_label && --LABEL_NUSES (prev_label) == 0) 2072 delete_insn (prev_label); 2073 continue; 2074 } 2075 else 2076 { 2077 /* Detect a jump to a jump. */ 2078 2079 nlabel = follow_jumps (JUMP_LABEL (insn)); 2080 if (nlabel != JUMP_LABEL (insn) 2081 && redirect_jump (insn, nlabel)) 2082 { 2083 changed = 1; 2084 next = insn; 2085 } 2086 2087 /* Look for if (foo) bar; else break; */ 2088 /* The insns look like this: 2089 insn = condjump label1; 2090 ...range1 (some insns)... 2091 jump label2; 2092 label1: 2093 ...range2 (some insns)... 2094 jump somewhere unconditionally 2095 label2: */ 2096 { 2097 rtx label1 = next_label (insn); 2098 rtx range1end = label1 ? prev_active_insn (label1) : 0; 2099 /* Don't do this optimization on the first round, so that 2100 jump-around-a-jump gets simplified before we ask here 2101 whether a jump is unconditional. 2102 2103 Also don't do it when we are called after reload since 2104 it will confuse reorg. */ 2105 if (! first 2106 && (reload_completed ? ! flag_delayed_branch : 1) 2107 /* Make sure INSN is something we can invert. */ 2108 && condjump_p (insn) 2109 && label1 != 0 2110 && JUMP_LABEL (insn) == label1 2111 && LABEL_NUSES (label1) == 1 2112 && GET_CODE (range1end) == JUMP_INSN 2113 && simplejump_p (range1end)) 2114 { 2115 rtx label2 = next_label (label1); 2116 rtx range2end = label2 ? prev_active_insn (label2) : 0; 2117 if (range1end != range2end 2118 && JUMP_LABEL (range1end) == label2 2119 && GET_CODE (range2end) == JUMP_INSN 2120 && GET_CODE (NEXT_INSN (range2end)) == BARRIER 2121 /* Invert the jump condition, so we 2122 still execute the same insns in each case. */ 2123 && invert_jump (insn, label1)) 2124 { 2125 rtx range1beg = next_active_insn (insn); 2126 rtx range2beg = next_active_insn (label1); 2127 rtx range1after, range2after; 2128 rtx range1before, range2before; 2129 rtx rangenext; 2130 2131 /* Include in each range any notes before it, to be 2132 sure that we get the line number note if any, even 2133 if there are other notes here. */ 2134 while (PREV_INSN (range1beg) 2135 && GET_CODE (PREV_INSN (range1beg)) == NOTE) 2136 range1beg = PREV_INSN (range1beg); 2137 2138 while (PREV_INSN (range2beg) 2139 && GET_CODE (PREV_INSN (range2beg)) == NOTE) 2140 range2beg = PREV_INSN (range2beg); 2141 2142 /* Don't move NOTEs for blocks or loops; shift them 2143 outside the ranges, where they'll stay put. */ 2144 range1beg = squeeze_notes (range1beg, range1end); 2145 range2beg = squeeze_notes (range2beg, range2end); 2146 2147 /* Get current surrounds of the 2 ranges. */ 2148 range1before = PREV_INSN (range1beg); 2149 range2before = PREV_INSN (range2beg); 2150 range1after = NEXT_INSN (range1end); 2151 range2after = NEXT_INSN (range2end); 2152 2153 /* Splice range2 where range1 was. */ 2154 NEXT_INSN (range1before) = range2beg; 2155 PREV_INSN (range2beg) = range1before; 2156 NEXT_INSN (range2end) = range1after; 2157 PREV_INSN (range1after) = range2end; 2158 /* Splice range1 where range2 was. */ 2159 NEXT_INSN (range2before) = range1beg; 2160 PREV_INSN (range1beg) = range2before; 2161 NEXT_INSN (range1end) = range2after; 2162 PREV_INSN (range2after) = range1end; 2163 2164 /* Check for a loop end note between the end of 2165 range2, and the next code label. If there is one, 2166 then what we have really seen is 2167 if (foo) break; end_of_loop; 2168 and moved the break sequence outside the loop. 2169 We must move the LOOP_END note to where the 2170 loop really ends now, or we will confuse loop 2171 optimization. Stop if we find a LOOP_BEG note 2172 first, since we don't want to move the LOOP_END 2173 note in that case. */ 2174 for (;range2after != label2; range2after = rangenext) 2175 { 2176 rangenext = NEXT_INSN (range2after); 2177 if (GET_CODE (range2after) == NOTE) 2178 { 2179 if (NOTE_LINE_NUMBER (range2after) 2180 == NOTE_INSN_LOOP_END) 2181 { 2182 NEXT_INSN (PREV_INSN (range2after)) 2183 = rangenext; 2184 PREV_INSN (rangenext) 2185 = PREV_INSN (range2after); 2186 PREV_INSN (range2after) 2187 = PREV_INSN (range1beg); 2188 NEXT_INSN (range2after) = range1beg; 2189 NEXT_INSN (PREV_INSN (range1beg)) 2190 = range2after; 2191 PREV_INSN (range1beg) = range2after; 2192 } 2193 else if (NOTE_LINE_NUMBER (range2after) 2194 == NOTE_INSN_LOOP_BEG) 2195 break; 2196 } 2197 } 2198 changed = 1; 2199 continue; 2200 } 2201 } 2202 } 2203 2204 /* Now that the jump has been tensioned, 2205 try cross jumping: check for identical code 2206 before the jump and before its target label. */ 2207 2208 /* First, cross jumping of conditional jumps: */ 2209 2210 if (cross_jump && condjump_p (insn)) 2211 { 2212 rtx newjpos, newlpos; 2213 rtx x = prev_real_insn (JUMP_LABEL (insn)); 2214 2215 /* A conditional jump may be crossjumped 2216 only if the place it jumps to follows 2217 an opposing jump that comes back here. */ 2218 2219 if (x != 0 && ! jump_back_p (x, insn)) 2220 /* We have no opposing jump; 2221 cannot cross jump this insn. */ 2222 x = 0; 2223 2224 newjpos = 0; 2225 /* TARGET is nonzero if it is ok to cross jump 2226 to code before TARGET. If so, see if matches. */ 2227 if (x != 0) 2228 find_cross_jump (insn, x, 2, 2229 &newjpos, &newlpos); 2230 2231 if (newjpos != 0) 2232 { 2233 do_cross_jump (insn, newjpos, newlpos); 2234 /* Make the old conditional jump 2235 into an unconditional one. */ 2236 SET_SRC (PATTERN (insn)) 2237 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn)); 2238 INSN_CODE (insn) = -1; 2239 emit_barrier_after (insn); 2240 /* Add to jump_chain unless this is a new label 2241 whose UID is too large. */ 2242 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain) 2243 { 2244 jump_chain[INSN_UID (insn)] 2245 = jump_chain[INSN_UID (JUMP_LABEL (insn))]; 2246 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn; 2247 } 2248 changed = 1; 2249 next = insn; 2250 } 2251 } 2252 2253 /* Cross jumping of unconditional jumps: 2254 a few differences. */ 2255 2256 if (cross_jump && simplejump_p (insn)) 2257 { 2258 rtx newjpos, newlpos; 2259 rtx target; 2260 2261 newjpos = 0; 2262 2263 /* TARGET is nonzero if it is ok to cross jump 2264 to code before TARGET. If so, see if matches. */ 2265 find_cross_jump (insn, JUMP_LABEL (insn), 1, 2266 &newjpos, &newlpos); 2267 2268 /* If cannot cross jump to code before the label, 2269 see if we can cross jump to another jump to 2270 the same label. */ 2271 /* Try each other jump to this label. */ 2272 if (INSN_UID (JUMP_LABEL (insn)) < max_uid) 2273 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))]; 2274 target != 0 && newjpos == 0; 2275 target = jump_chain[INSN_UID (target)]) 2276 if (target != insn 2277 && JUMP_LABEL (target) == JUMP_LABEL (insn) 2278 /* Ignore TARGET if it's deleted. */ 2279 && ! INSN_DELETED_P (target)) 2280 find_cross_jump (insn, target, 2, 2281 &newjpos, &newlpos); 2282 2283 if (newjpos != 0) 2284 { 2285 do_cross_jump (insn, newjpos, newlpos); 2286 changed = 1; 2287 next = insn; 2288 } 2289 } 2290 2291 /* This code was dead in the previous jump.c! */ 2292 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN) 2293 { 2294 /* Return insns all "jump to the same place" 2295 so we can cross-jump between any two of them. */ 2296 2297 rtx newjpos, newlpos, target; 2298 2299 newjpos = 0; 2300 2301 /* If cannot cross jump to code before the label, 2302 see if we can cross jump to another jump to 2303 the same label. */ 2304 /* Try each other jump to this label. */ 2305 for (target = jump_chain[0]; 2306 target != 0 && newjpos == 0; 2307 target = jump_chain[INSN_UID (target)]) 2308 if (target != insn 2309 && ! INSN_DELETED_P (target) 2310 && GET_CODE (PATTERN (target)) == RETURN) 2311 find_cross_jump (insn, target, 2, 2312 &newjpos, &newlpos); 2313 2314 if (newjpos != 0) 2315 { 2316 do_cross_jump (insn, newjpos, newlpos); 2317 changed = 1; 2318 next = insn; 2319 } 2320 } 2321 } 2322 } 2323 2324 first = 0; 2325 } 2326 2327 /* Delete extraneous line number notes. 2328 Note that two consecutive notes for different lines are not really 2329 extraneous. There should be some indication where that line belonged, 2330 even if it became empty. */ 2331 2332 { 2333 rtx last_note = 0; 2334 2335 for (insn = f; insn; insn = NEXT_INSN (insn)) 2336 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0) 2337 { 2338 /* Delete this note if it is identical to previous note. */ 2339 if (last_note 2340 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note) 2341 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note)) 2342 { 2343 delete_insn (insn); 2344 continue; 2345 } 2346 2347 last_note = insn; 2348 } 2349 } 2350 2351#ifdef HAVE_return 2352 if (HAVE_return) 2353 { 2354 /* If we fall through to the epilogue, see if we can insert a RETURN insn 2355 in front of it. If the machine allows it at this point (we might be 2356 after reload for a leaf routine), it will improve optimization for it 2357 to be there. We do this both here and at the start of this pass since 2358 the RETURN might have been deleted by some of our optimizations. */ 2359 insn = get_last_insn (); 2360 while (insn && GET_CODE (insn) == NOTE) 2361 insn = PREV_INSN (insn); 2362 2363 if (insn && GET_CODE (insn) != BARRIER) 2364 { 2365 emit_jump_insn (gen_return ()); 2366 emit_barrier (); 2367 } 2368 } 2369#endif 2370 2371 /* See if there is still a NOTE_INSN_FUNCTION_END in this function. 2372 If so, delete it, and record that this function can drop off the end. */ 2373 2374 insn = last_insn; 2375 { 2376 int n_labels = 1; 2377 while (insn 2378 /* One label can follow the end-note: the return label. */ 2379 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0) 2380 /* Ordinary insns can follow it if returning a structure. */ 2381 || GET_CODE (insn) == INSN 2382 /* If machine uses explicit RETURN insns, no epilogue, 2383 then one of them follows the note. */ 2384 || (GET_CODE (insn) == JUMP_INSN 2385 && GET_CODE (PATTERN (insn)) == RETURN) 2386 /* A barrier can follow the return insn. */ 2387 || GET_CODE (insn) == BARRIER 2388 /* Other kinds of notes can follow also. */ 2389 || (GET_CODE (insn) == NOTE 2390 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END))) 2391 insn = PREV_INSN (insn); 2392 } 2393 2394 /* Report if control can fall through at the end of the function. */ 2395 if (insn && GET_CODE (insn) == NOTE 2396 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END) 2397 { 2398 can_reach_end = 1; 2399 delete_insn (insn); 2400 } 2401 2402 /* Show JUMP_CHAIN no longer valid. */ 2403 jump_chain = 0; 2404} 2405 2406/* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional 2407 jump. Assume that this unconditional jump is to the exit test code. If 2408 the code is sufficiently simple, make a copy of it before INSN, 2409 followed by a jump to the exit of the loop. Then delete the unconditional 2410 jump after INSN. 2411 2412 Return 1 if we made the change, else 0. 2413 2414 This is only safe immediately after a regscan pass because it uses the 2415 values of regno_first_uid and regno_last_uid. */ 2416 2417static int 2418duplicate_loop_exit_test (loop_start) 2419 rtx loop_start; 2420{ 2421 rtx insn, set, reg, p, link; 2422 rtx copy = 0; 2423 int num_insns = 0; 2424 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start))); 2425 rtx lastexit; 2426 int max_reg = max_reg_num (); 2427 rtx *reg_map = 0; 2428 2429 /* Scan the exit code. We do not perform this optimization if any insn: 2430 2431 is a CALL_INSN 2432 is a CODE_LABEL 2433 has a REG_RETVAL or REG_LIBCALL note (hard to adjust) 2434 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop 2435 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes 2436 are not valid 2437 2438 2439 We also do not do this if we find an insn with ASM_OPERANDS. While 2440 this restriction should not be necessary, copying an insn with 2441 ASM_OPERANDS can confuse asm_noperands in some cases. 2442 2443 Also, don't do this if the exit code is more than 20 insns. */ 2444 2445 for (insn = exitcode; 2446 insn 2447 && ! (GET_CODE (insn) == NOTE 2448 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END); 2449 insn = NEXT_INSN (insn)) 2450 { 2451 switch (GET_CODE (insn)) 2452 { 2453 case CODE_LABEL: 2454 case CALL_INSN: 2455 return 0; 2456 case NOTE: 2457 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is 2458 a jump immediately after the loop start that branches outside 2459 the loop but within an outer loop, near the exit test. 2460 If we copied this exit test and created a phony 2461 NOTE_INSN_LOOP_VTOP, this could make instructions immediately 2462 before the exit test look like these could be safely moved 2463 out of the loop even if they actually may be never executed. 2464 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */ 2465 2466 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG 2467 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT) 2468 return 0; 2469 2470 if (optimize < 2 2471 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG 2472 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)) 2473 /* If we were to duplicate this code, we would not move 2474 the BLOCK notes, and so debugging the moved code would 2475 be difficult. Thus, we only move the code with -O2 or 2476 higher. */ 2477 return 0; 2478 2479 break; 2480 case JUMP_INSN: 2481 case INSN: 2482 if (++num_insns > 20 2483 || find_reg_note (insn, REG_RETVAL, NULL_RTX) 2484 || find_reg_note (insn, REG_LIBCALL, NULL_RTX) 2485 || asm_noperands (PATTERN (insn)) > 0) 2486 return 0; 2487 break; 2488 default: 2489 break; 2490 } 2491 } 2492 2493 /* Unless INSN is zero, we can do the optimization. */ 2494 if (insn == 0) 2495 return 0; 2496 2497 lastexit = insn; 2498 2499 /* See if any insn sets a register only used in the loop exit code and 2500 not a user variable. If so, replace it with a new register. */ 2501 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn)) 2502 if (GET_CODE (insn) == INSN 2503 && (set = single_set (insn)) != 0 2504 && ((reg = SET_DEST (set), GET_CODE (reg) == REG) 2505 || (GET_CODE (reg) == SUBREG 2506 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG))) 2507 && REGNO (reg) >= FIRST_PSEUDO_REGISTER 2508 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn)) 2509 { 2510 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p)) 2511 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p)) 2512 break; 2513 2514 if (p != lastexit) 2515 { 2516 /* We can do the replacement. Allocate reg_map if this is the 2517 first replacement we found. */ 2518 if (reg_map == 0) 2519 { 2520 reg_map = (rtx *) alloca (max_reg * sizeof (rtx)); 2521 bzero ((char *) reg_map, max_reg * sizeof (rtx)); 2522 } 2523 2524 REG_LOOP_TEST_P (reg) = 1; 2525 2526 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg)); 2527 } 2528 } 2529 2530 /* Now copy each insn. */ 2531 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn)) 2532 switch (GET_CODE (insn)) 2533 { 2534 case BARRIER: 2535 copy = emit_barrier_before (loop_start); 2536 break; 2537 case NOTE: 2538 /* Only copy line-number notes. */ 2539 if (NOTE_LINE_NUMBER (insn) >= 0) 2540 { 2541 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start); 2542 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn); 2543 } 2544 break; 2545 2546 case INSN: 2547 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start); 2548 if (reg_map) 2549 replace_regs (PATTERN (copy), reg_map, max_reg, 1); 2550 2551 mark_jump_label (PATTERN (copy), copy, 0); 2552 2553 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will 2554 make them. */ 2555 for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) 2556 if (REG_NOTE_KIND (link) != REG_LABEL) 2557 REG_NOTES (copy) 2558 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link), 2559 XEXP (link, 0), 2560 REG_NOTES (copy))); 2561 if (reg_map && REG_NOTES (copy)) 2562 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1); 2563 break; 2564 2565 case JUMP_INSN: 2566 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start); 2567 if (reg_map) 2568 replace_regs (PATTERN (copy), reg_map, max_reg, 1); 2569 mark_jump_label (PATTERN (copy), copy, 0); 2570 if (REG_NOTES (insn)) 2571 { 2572 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn)); 2573 if (reg_map) 2574 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1); 2575 } 2576 2577 /* If this is a simple jump, add it to the jump chain. */ 2578 2579 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy) 2580 && simplejump_p (copy)) 2581 { 2582 jump_chain[INSN_UID (copy)] 2583 = jump_chain[INSN_UID (JUMP_LABEL (copy))]; 2584 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy; 2585 } 2586 break; 2587 2588 default: 2589 abort (); 2590 } 2591 2592 /* Now clean up by emitting a jump to the end label and deleting the jump 2593 at the start of the loop. */ 2594 if (! copy || GET_CODE (copy) != BARRIER) 2595 { 2596 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)), 2597 loop_start); 2598 mark_jump_label (PATTERN (copy), copy, 0); 2599 if (INSN_UID (copy) < max_jump_chain 2600 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain) 2601 { 2602 jump_chain[INSN_UID (copy)] 2603 = jump_chain[INSN_UID (JUMP_LABEL (copy))]; 2604 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy; 2605 } 2606 emit_barrier_before (loop_start); 2607 } 2608 2609 /* Mark the exit code as the virtual top of the converted loop. */ 2610 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode); 2611 2612 delete_insn (next_nonnote_insn (loop_start)); 2613 2614 return 1; 2615} 2616 2617/* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and 2618 loop-end notes between START and END out before START. Assume that 2619 END is not such a note. START may be such a note. Returns the value 2620 of the new starting insn, which may be different if the original start 2621 was such a note. */ 2622 2623rtx 2624squeeze_notes (start, end) 2625 rtx start, end; 2626{ 2627 rtx insn; 2628 rtx next; 2629 2630 for (insn = start; insn != end; insn = next) 2631 { 2632 next = NEXT_INSN (insn); 2633 if (GET_CODE (insn) == NOTE 2634 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END 2635 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG 2636 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG 2637 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END 2638 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT 2639 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP)) 2640 { 2641 if (insn == start) 2642 start = next; 2643 else 2644 { 2645 rtx prev = PREV_INSN (insn); 2646 PREV_INSN (insn) = PREV_INSN (start); 2647 NEXT_INSN (insn) = start; 2648 NEXT_INSN (PREV_INSN (insn)) = insn; 2649 PREV_INSN (NEXT_INSN (insn)) = insn; 2650 NEXT_INSN (prev) = next; 2651 PREV_INSN (next) = prev; 2652 } 2653 } 2654 } 2655 2656 return start; 2657} 2658 2659/* Compare the instructions before insn E1 with those before E2 2660 to find an opportunity for cross jumping. 2661 (This means detecting identical sequences of insns followed by 2662 jumps to the same place, or followed by a label and a jump 2663 to that label, and replacing one with a jump to the other.) 2664 2665 Assume E1 is a jump that jumps to label E2 2666 (that is not always true but it might as well be). 2667 Find the longest possible equivalent sequences 2668 and store the first insns of those sequences into *F1 and *F2. 2669 Store zero there if no equivalent preceding instructions are found. 2670 2671 We give up if we find a label in stream 1. 2672 Actually we could transfer that label into stream 2. */ 2673 2674static void 2675find_cross_jump (e1, e2, minimum, f1, f2) 2676 rtx e1, e2; 2677 int minimum; 2678 rtx *f1, *f2; 2679{ 2680 register rtx i1 = e1, i2 = e2; 2681 register rtx p1, p2; 2682 int lose = 0; 2683 2684 rtx last1 = 0, last2 = 0; 2685 rtx afterlast1 = 0, afterlast2 = 0; 2686 2687 *f1 = 0; 2688 *f2 = 0; 2689 2690 while (1) 2691 { 2692 i1 = prev_nonnote_insn (i1); 2693 2694 i2 = PREV_INSN (i2); 2695 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL)) 2696 i2 = PREV_INSN (i2); 2697 2698 if (i1 == 0) 2699 break; 2700 2701 /* Don't allow the range of insns preceding E1 or E2 2702 to include the other (E2 or E1). */ 2703 if (i2 == e1 || i1 == e2) 2704 break; 2705 2706 /* If we will get to this code by jumping, those jumps will be 2707 tensioned to go directly to the new label (before I2), 2708 so this cross-jumping won't cost extra. So reduce the minimum. */ 2709 if (GET_CODE (i1) == CODE_LABEL) 2710 { 2711 --minimum; 2712 break; 2713 } 2714 2715 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2)) 2716 break; 2717 2718 /* Avoid moving insns across EH regions. 2719 2720 ??? This is only necessary if i1 or i2 can throw an exception. */ 2721 if (flag_exceptions 2722 && !in_same_eh_region (i1, i2)) 2723 break; 2724 2725 p1 = PATTERN (i1); 2726 p2 = PATTERN (i2); 2727 2728 /* If this is a CALL_INSN, compare register usage information. 2729 If we don't check this on stack register machines, the two 2730 CALL_INSNs might be merged leaving reg-stack.c with mismatching 2731 numbers of stack registers in the same basic block. 2732 If we don't check this on machines with delay slots, a delay slot may 2733 be filled that clobbers a parameter expected by the subroutine. 2734 2735 ??? We take the simple route for now and assume that if they're 2736 equal, they were constructed identically. */ 2737 2738 if (GET_CODE (i1) == CALL_INSN 2739 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), 2740 CALL_INSN_FUNCTION_USAGE (i2))) 2741 lose = 1; 2742 2743#ifdef STACK_REGS 2744 /* If cross_jump_death_matters is not 0, the insn's mode 2745 indicates whether or not the insn contains any stack-like 2746 regs. */ 2747 2748 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode) 2749 { 2750 /* If register stack conversion has already been done, then 2751 death notes must also be compared before it is certain that 2752 the two instruction streams match. */ 2753 2754 rtx note; 2755 HARD_REG_SET i1_regset, i2_regset; 2756 2757 CLEAR_HARD_REG_SET (i1_regset); 2758 CLEAR_HARD_REG_SET (i2_regset); 2759 2760 for (note = REG_NOTES (i1); note; note = XEXP (note, 1)) 2761 if (REG_NOTE_KIND (note) == REG_DEAD 2762 && STACK_REG_P (XEXP (note, 0))) 2763 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0))); 2764 2765 for (note = REG_NOTES (i2); note; note = XEXP (note, 1)) 2766 if (REG_NOTE_KIND (note) == REG_DEAD 2767 && STACK_REG_P (XEXP (note, 0))) 2768 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0))); 2769 2770 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done); 2771 2772 lose = 1; 2773 2774 done: 2775 ; 2776 } 2777#endif 2778 2779 /* Don't allow old-style asm or volatile extended asms to be accepted 2780 for cross jumping purposes. It is conceptually correct to allow 2781 them, since cross-jumping preserves the dynamic instruction order 2782 even though it is changing the static instruction order. However, 2783 if an asm is being used to emit an assembler pseudo-op, such as 2784 the MIPS `.set reorder' pseudo-op, then the static instruction order 2785 matters and it must be preserved. */ 2786 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT 2787 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1)) 2788 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2))) 2789 lose = 1; 2790 2791 if (lose || GET_CODE (p1) != GET_CODE (p2) 2792 || ! rtx_renumbered_equal_p (p1, p2)) 2793 { 2794 /* The following code helps take care of G++ cleanups. */ 2795 rtx equiv1; 2796 rtx equiv2; 2797 2798 if (!lose && GET_CODE (p1) == GET_CODE (p2) 2799 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0 2800 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0) 2801 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0 2802 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0) 2803 /* If the equivalences are not to a constant, they may 2804 reference pseudos that no longer exist, so we can't 2805 use them. */ 2806 && CONSTANT_P (XEXP (equiv1, 0)) 2807 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))) 2808 { 2809 rtx s1 = single_set (i1); 2810 rtx s2 = single_set (i2); 2811 if (s1 != 0 && s2 != 0 2812 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2))) 2813 { 2814 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1); 2815 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1); 2816 if (! rtx_renumbered_equal_p (p1, p2)) 2817 cancel_changes (0); 2818 else if (apply_change_group ()) 2819 goto win; 2820 } 2821 } 2822 2823 /* Insns fail to match; cross jumping is limited to the following 2824 insns. */ 2825 2826#ifdef HAVE_cc0 2827 /* Don't allow the insn after a compare to be shared by 2828 cross-jumping unless the compare is also shared. 2829 Here, if either of these non-matching insns is a compare, 2830 exclude the following insn from possible cross-jumping. */ 2831 if (sets_cc0_p (p1) || sets_cc0_p (p2)) 2832 last1 = afterlast1, last2 = afterlast2, ++minimum; 2833#endif 2834 2835 /* If cross-jumping here will feed a jump-around-jump 2836 optimization, this jump won't cost extra, so reduce 2837 the minimum. */ 2838 if (GET_CODE (i1) == JUMP_INSN 2839 && JUMP_LABEL (i1) 2840 && prev_real_insn (JUMP_LABEL (i1)) == e1) 2841 --minimum; 2842 break; 2843 } 2844 2845 win: 2846 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER) 2847 { 2848 /* Ok, this insn is potentially includable in a cross-jump here. */ 2849 afterlast1 = last1, afterlast2 = last2; 2850 last1 = i1, last2 = i2, --minimum; 2851 } 2852 } 2853 2854 if (minimum <= 0 && last1 != 0 && last1 != e1) 2855 *f1 = last1, *f2 = last2; 2856} 2857 2858static void 2859do_cross_jump (insn, newjpos, newlpos) 2860 rtx insn, newjpos, newlpos; 2861{ 2862 /* Find an existing label at this point 2863 or make a new one if there is none. */ 2864 register rtx label = get_label_before (newlpos); 2865 2866 /* Make the same jump insn jump to the new point. */ 2867 if (GET_CODE (PATTERN (insn)) == RETURN) 2868 { 2869 /* Remove from jump chain of returns. */ 2870 delete_from_jump_chain (insn); 2871 /* Change the insn. */ 2872 PATTERN (insn) = gen_jump (label); 2873 INSN_CODE (insn) = -1; 2874 JUMP_LABEL (insn) = label; 2875 LABEL_NUSES (label)++; 2876 /* Add to new the jump chain. */ 2877 if (INSN_UID (label) < max_jump_chain 2878 && INSN_UID (insn) < max_jump_chain) 2879 { 2880 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)]; 2881 jump_chain[INSN_UID (label)] = insn; 2882 } 2883 } 2884 else 2885 redirect_jump (insn, label); 2886 2887 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL 2888 or REG_EQUIV note in the NEWLPOS stream that isn't also present in 2889 the NEWJPOS stream. */ 2890 2891 while (newjpos != insn) 2892 { 2893 rtx lnote; 2894 2895 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1)) 2896 if ((REG_NOTE_KIND (lnote) == REG_EQUAL 2897 || REG_NOTE_KIND (lnote) == REG_EQUIV) 2898 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0)) 2899 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0))) 2900 remove_note (newlpos, lnote); 2901 2902 delete_insn (newjpos); 2903 newjpos = next_real_insn (newjpos); 2904 newlpos = next_real_insn (newlpos); 2905 } 2906} 2907 2908/* Return the label before INSN, or put a new label there. */ 2909 2910rtx 2911get_label_before (insn) 2912 rtx insn; 2913{ 2914 rtx label; 2915 2916 /* Find an existing label at this point 2917 or make a new one if there is none. */ 2918 label = prev_nonnote_insn (insn); 2919 2920 if (label == 0 || GET_CODE (label) != CODE_LABEL) 2921 { 2922 rtx prev = PREV_INSN (insn); 2923 2924 label = gen_label_rtx (); 2925 emit_label_after (label, prev); 2926 LABEL_NUSES (label) = 0; 2927 } 2928 return label; 2929} 2930 2931/* Return the label after INSN, or put a new label there. */ 2932 2933rtx 2934get_label_after (insn) 2935 rtx insn; 2936{ 2937 rtx label; 2938 2939 /* Find an existing label at this point 2940 or make a new one if there is none. */ 2941 label = next_nonnote_insn (insn); 2942 2943 if (label == 0 || GET_CODE (label) != CODE_LABEL) 2944 { 2945 label = gen_label_rtx (); 2946 emit_label_after (label, insn); 2947 LABEL_NUSES (label) = 0; 2948 } 2949 return label; 2950} 2951 2952/* Return 1 if INSN is a jump that jumps to right after TARGET 2953 only on the condition that TARGET itself would drop through. 2954 Assumes that TARGET is a conditional jump. */ 2955 2956static int 2957jump_back_p (insn, target) 2958 rtx insn, target; 2959{ 2960 rtx cinsn, ctarget; 2961 enum rtx_code codei, codet; 2962 2963 if (simplejump_p (insn) || ! condjump_p (insn) 2964 || simplejump_p (target) 2965 || target != prev_real_insn (JUMP_LABEL (insn))) 2966 return 0; 2967 2968 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0); 2969 ctarget = XEXP (SET_SRC (PATTERN (target)), 0); 2970 2971 codei = GET_CODE (cinsn); 2972 codet = GET_CODE (ctarget); 2973 2974 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx) 2975 { 2976 if (! can_reverse_comparison_p (cinsn, insn)) 2977 return 0; 2978 codei = reverse_condition (codei); 2979 } 2980 2981 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx) 2982 { 2983 if (! can_reverse_comparison_p (ctarget, target)) 2984 return 0; 2985 codet = reverse_condition (codet); 2986 } 2987 2988 return (codei == codet 2989 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0)) 2990 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1))); 2991} 2992 2993/* Given a comparison, COMPARISON, inside a conditional jump insn, INSN, 2994 return non-zero if it is safe to reverse this comparison. It is if our 2995 floating-point is not IEEE, if this is an NE or EQ comparison, or if 2996 this is known to be an integer comparison. */ 2997 2998int 2999can_reverse_comparison_p (comparison, insn) 3000 rtx comparison; 3001 rtx insn; 3002{ 3003 rtx arg0; 3004 3005 /* If this is not actually a comparison, we can't reverse it. */ 3006 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<') 3007 return 0; 3008 3009 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT 3010 /* If this is an NE comparison, it is safe to reverse it to an EQ 3011 comparison and vice versa, even for floating point. If no operands 3012 are NaNs, the reversal is valid. If some operand is a NaN, EQ is 3013 always false and NE is always true, so the reversal is also valid. */ 3014 || flag_fast_math 3015 || GET_CODE (comparison) == NE 3016 || GET_CODE (comparison) == EQ) 3017 return 1; 3018 3019 arg0 = XEXP (comparison, 0); 3020 3021 /* Make sure ARG0 is one of the actual objects being compared. If we 3022 can't do this, we can't be sure the comparison can be reversed. 3023 3024 Handle cc0 and a MODE_CC register. */ 3025 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC) 3026#ifdef HAVE_cc0 3027 || arg0 == cc0_rtx 3028#endif 3029 ) 3030 { 3031 rtx prev = prev_nonnote_insn (insn); 3032 rtx set = single_set (prev); 3033 3034 if (set == 0 || SET_DEST (set) != arg0) 3035 return 0; 3036 3037 arg0 = SET_SRC (set); 3038 3039 if (GET_CODE (arg0) == COMPARE) 3040 arg0 = XEXP (arg0, 0); 3041 } 3042 3043 /* We can reverse this if ARG0 is a CONST_INT or if its mode is 3044 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */ 3045 return (GET_CODE (arg0) == CONST_INT 3046 || (GET_MODE (arg0) != VOIDmode 3047 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC 3048 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT)); 3049} 3050 3051/* Given an rtx-code for a comparison, return the code 3052 for the negated comparison. 3053 WATCH OUT! reverse_condition is not safe to use on a jump 3054 that might be acting on the results of an IEEE floating point comparison, 3055 because of the special treatment of non-signaling nans in comparisons. 3056 Use can_reverse_comparison_p to be sure. */ 3057 3058enum rtx_code 3059reverse_condition (code) 3060 enum rtx_code code; 3061{ 3062 switch (code) 3063 { 3064 case EQ: 3065 return NE; 3066 3067 case NE: 3068 return EQ; 3069 3070 case GT: 3071 return LE; 3072 3073 case GE: 3074 return LT; 3075 3076 case LT: 3077 return GE; 3078 3079 case LE: 3080 return GT; 3081 3082 case GTU: 3083 return LEU; 3084 3085 case GEU: 3086 return LTU; 3087 3088 case LTU: 3089 return GEU; 3090 3091 case LEU: 3092 return GTU; 3093 3094 default: 3095 abort (); 3096 return UNKNOWN; 3097 } 3098} 3099 3100/* Similar, but return the code when two operands of a comparison are swapped. 3101 This IS safe for IEEE floating-point. */ 3102 3103enum rtx_code 3104swap_condition (code) 3105 enum rtx_code code; 3106{ 3107 switch (code) 3108 { 3109 case EQ: 3110 case NE: 3111 return code; 3112 3113 case GT: 3114 return LT; 3115 3116 case GE: 3117 return LE; 3118 3119 case LT: 3120 return GT; 3121 3122 case LE: 3123 return GE; 3124 3125 case GTU: 3126 return LTU; 3127 3128 case GEU: 3129 return LEU; 3130 3131 case LTU: 3132 return GTU; 3133 3134 case LEU: 3135 return GEU; 3136 3137 default: 3138 abort (); 3139 return UNKNOWN; 3140 } 3141} 3142 3143/* Given a comparison CODE, return the corresponding unsigned comparison. 3144 If CODE is an equality comparison or already an unsigned comparison, 3145 CODE is returned. */ 3146 3147enum rtx_code 3148unsigned_condition (code) 3149 enum rtx_code code; 3150{ 3151 switch (code) 3152 { 3153 case EQ: 3154 case NE: 3155 case GTU: 3156 case GEU: 3157 case LTU: 3158 case LEU: 3159 return code; 3160 3161 case GT: 3162 return GTU; 3163 3164 case GE: 3165 return GEU; 3166 3167 case LT: 3168 return LTU; 3169 3170 case LE: 3171 return LEU; 3172 3173 default: 3174 abort (); 3175 } 3176} 3177 3178/* Similarly, return the signed version of a comparison. */ 3179 3180enum rtx_code 3181signed_condition (code) 3182 enum rtx_code code; 3183{ 3184 switch (code) 3185 { 3186 case EQ: 3187 case NE: 3188 case GT: 3189 case GE: 3190 case LT: 3191 case LE: 3192 return code; 3193 3194 case GTU: 3195 return GT; 3196 3197 case GEU: 3198 return GE; 3199 3200 case LTU: 3201 return LT; 3202 3203 case LEU: 3204 return LE; 3205 3206 default: 3207 abort (); 3208 } 3209} 3210 3211/* Return non-zero if CODE1 is more strict than CODE2, i.e., if the 3212 truth of CODE1 implies the truth of CODE2. */ 3213 3214int 3215comparison_dominates_p (code1, code2) 3216 enum rtx_code code1, code2; 3217{ 3218 if (code1 == code2) 3219 return 1; 3220 3221 switch (code1) 3222 { 3223 case EQ: 3224 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU) 3225 return 1; 3226 break; 3227 3228 case LT: 3229 if (code2 == LE || code2 == NE) 3230 return 1; 3231 break; 3232 3233 case GT: 3234 if (code2 == GE || code2 == NE) 3235 return 1; 3236 break; 3237 3238 case LTU: 3239 if (code2 == LEU || code2 == NE) 3240 return 1; 3241 break; 3242 3243 case GTU: 3244 if (code2 == GEU || code2 == NE) 3245 return 1; 3246 break; 3247 3248 default: 3249 break; 3250 } 3251 3252 return 0; 3253} 3254 3255/* Return 1 if INSN is an unconditional jump and nothing else. */ 3256 3257int 3258simplejump_p (insn) 3259 rtx insn; 3260{ 3261 return (GET_CODE (insn) == JUMP_INSN 3262 && GET_CODE (PATTERN (insn)) == SET 3263 && GET_CODE (SET_DEST (PATTERN (insn))) == PC 3264 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF); 3265} 3266 3267/* Return nonzero if INSN is a (possibly) conditional jump 3268 and nothing more. */ 3269 3270int 3271condjump_p (insn) 3272 rtx insn; 3273{ 3274 register rtx x = PATTERN (insn); 3275 if (GET_CODE (x) != SET) 3276 return 0; 3277 if (GET_CODE (SET_DEST (x)) != PC) 3278 return 0; 3279 if (GET_CODE (SET_SRC (x)) == LABEL_REF) 3280 return 1; 3281 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE) 3282 return 0; 3283 if (XEXP (SET_SRC (x), 2) == pc_rtx 3284 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF 3285 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN)) 3286 return 1; 3287 if (XEXP (SET_SRC (x), 1) == pc_rtx 3288 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF 3289 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN)) 3290 return 1; 3291 return 0; 3292} 3293 3294/* Return nonzero if INSN is a (possibly) conditional jump 3295 and nothing more. */ 3296 3297int 3298condjump_in_parallel_p (insn) 3299 rtx insn; 3300{ 3301 register rtx x = PATTERN (insn); 3302 3303 if (GET_CODE (x) != PARALLEL) 3304 return 0; 3305 else 3306 x = XVECEXP (x, 0, 0); 3307 3308 if (GET_CODE (x) != SET) 3309 return 0; 3310 if (GET_CODE (SET_DEST (x)) != PC) 3311 return 0; 3312 if (GET_CODE (SET_SRC (x)) == LABEL_REF) 3313 return 1; 3314 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE) 3315 return 0; 3316 if (XEXP (SET_SRC (x), 2) == pc_rtx 3317 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF 3318 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN)) 3319 return 1; 3320 if (XEXP (SET_SRC (x), 1) == pc_rtx 3321 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF 3322 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN)) 3323 return 1; 3324 return 0; 3325} 3326 3327/* Return 1 if X is an RTX that does nothing but set the condition codes 3328 and CLOBBER or USE registers. 3329 Return -1 if X does explicitly set the condition codes, 3330 but also does other things. */ 3331 3332int 3333sets_cc0_p (x) 3334 rtx x; 3335{ 3336#ifdef HAVE_cc0 3337 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx) 3338 return 1; 3339 if (GET_CODE (x) == PARALLEL) 3340 { 3341 int i; 3342 int sets_cc0 = 0; 3343 int other_things = 0; 3344 for (i = XVECLEN (x, 0) - 1; i >= 0; i--) 3345 { 3346 if (GET_CODE (XVECEXP (x, 0, i)) == SET 3347 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx) 3348 sets_cc0 = 1; 3349 else if (GET_CODE (XVECEXP (x, 0, i)) == SET) 3350 other_things = 1; 3351 } 3352 return ! sets_cc0 ? 0 : other_things ? -1 : 1; 3353 } 3354 return 0; 3355#else 3356 abort (); 3357#endif 3358} 3359 3360/* Follow any unconditional jump at LABEL; 3361 return the ultimate label reached by any such chain of jumps. 3362 If LABEL is not followed by a jump, return LABEL. 3363 If the chain loops or we can't find end, return LABEL, 3364 since that tells caller to avoid changing the insn. 3365 3366 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or 3367 a USE or CLOBBER. */ 3368 3369rtx 3370follow_jumps (label) 3371 rtx label; 3372{ 3373 register rtx insn; 3374 register rtx next; 3375 register rtx value = label; 3376 register int depth; 3377 3378 for (depth = 0; 3379 (depth < 10 3380 && (insn = next_active_insn (value)) != 0 3381 && GET_CODE (insn) == JUMP_INSN 3382 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn)) 3383 || GET_CODE (PATTERN (insn)) == RETURN) 3384 && (next = NEXT_INSN (insn)) 3385 && GET_CODE (next) == BARRIER); 3386 depth++) 3387 { 3388 /* Don't chain through the insn that jumps into a loop 3389 from outside the loop, 3390 since that would create multiple loop entry jumps 3391 and prevent loop optimization. */ 3392 rtx tem; 3393 if (!reload_completed) 3394 for (tem = value; tem != insn; tem = NEXT_INSN (tem)) 3395 if (GET_CODE (tem) == NOTE 3396 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG 3397 /* ??? Optional. Disables some optimizations, but makes 3398 gcov output more accurate with -O. */ 3399 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0))) 3400 return value; 3401 3402 /* If we have found a cycle, make the insn jump to itself. */ 3403 if (JUMP_LABEL (insn) == label) 3404 return label; 3405 3406 tem = next_active_insn (JUMP_LABEL (insn)); 3407 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC 3408 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC)) 3409 break; 3410 3411 value = JUMP_LABEL (insn); 3412 } 3413 if (depth == 10) 3414 return label; 3415 return value; 3416} 3417 3418/* Assuming that field IDX of X is a vector of label_refs, 3419 replace each of them by the ultimate label reached by it. 3420 Return nonzero if a change is made. 3421 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */ 3422 3423static int 3424tension_vector_labels (x, idx) 3425 register rtx x; 3426 register int idx; 3427{ 3428 int changed = 0; 3429 register int i; 3430 for (i = XVECLEN (x, idx) - 1; i >= 0; i--) 3431 { 3432 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0); 3433 register rtx nlabel = follow_jumps (olabel); 3434 if (nlabel && nlabel != olabel) 3435 { 3436 XEXP (XVECEXP (x, idx, i), 0) = nlabel; 3437 ++LABEL_NUSES (nlabel); 3438 if (--LABEL_NUSES (olabel) == 0) 3439 delete_insn (olabel); 3440 changed = 1; 3441 } 3442 } 3443 return changed; 3444} 3445 3446/* Find all CODE_LABELs referred to in X, and increment their use counts. 3447 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced 3448 in INSN, then store one of them in JUMP_LABEL (INSN). 3449 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL 3450 referenced in INSN, add a REG_LABEL note containing that label to INSN. 3451 Also, when there are consecutive labels, canonicalize on the last of them. 3452 3453 Note that two labels separated by a loop-beginning note 3454 must be kept distinct if we have not yet done loop-optimization, 3455 because the gap between them is where loop-optimize 3456 will want to move invariant code to. CROSS_JUMP tells us 3457 that loop-optimization is done with. 3458 3459 Once reload has completed (CROSS_JUMP non-zero), we need not consider 3460 two labels distinct if they are separated by only USE or CLOBBER insns. */ 3461 3462static void 3463mark_jump_label (x, insn, cross_jump) 3464 register rtx x; 3465 rtx insn; 3466 int cross_jump; 3467{ 3468 register RTX_CODE code = GET_CODE (x); 3469 register int i; 3470 register char *fmt; 3471 3472 switch (code) 3473 { 3474 case PC: 3475 case CC0: 3476 case REG: 3477 case SUBREG: 3478 case CONST_INT: 3479 case SYMBOL_REF: 3480 case CONST_DOUBLE: 3481 case CLOBBER: 3482 case CALL: 3483 return; 3484 3485 case MEM: 3486 /* If this is a constant-pool reference, see if it is a label. */ 3487 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF 3488 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0))) 3489 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump); 3490 break; 3491 3492 case LABEL_REF: 3493 { 3494 rtx label = XEXP (x, 0); 3495 rtx olabel = label; 3496 rtx note; 3497 rtx next; 3498 3499 if (GET_CODE (label) != CODE_LABEL) 3500 abort (); 3501 3502 /* Ignore references to labels of containing functions. */ 3503 if (LABEL_REF_NONLOCAL_P (x)) 3504 break; 3505 3506 /* If there are other labels following this one, 3507 replace it with the last of the consecutive labels. */ 3508 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next)) 3509 { 3510 if (GET_CODE (next) == CODE_LABEL) 3511 label = next; 3512 else if (cross_jump && GET_CODE (next) == INSN 3513 && (GET_CODE (PATTERN (next)) == USE 3514 || GET_CODE (PATTERN (next)) == CLOBBER)) 3515 continue; 3516 else if (GET_CODE (next) != NOTE) 3517 break; 3518 else if (! cross_jump 3519 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG 3520 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END 3521 /* ??? Optional. Disables some optimizations, but 3522 makes gcov output more accurate with -O. */ 3523 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0))) 3524 break; 3525 } 3526 3527 XEXP (x, 0) = label; 3528 if (! insn || ! INSN_DELETED_P (insn)) 3529 ++LABEL_NUSES (label); 3530 3531 if (insn) 3532 { 3533 if (GET_CODE (insn) == JUMP_INSN) 3534 JUMP_LABEL (insn) = label; 3535 3536 /* If we've changed OLABEL and we had a REG_LABEL note 3537 for it, update it as well. */ 3538 else if (label != olabel 3539 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0) 3540 XEXP (note, 0) = label; 3541 3542 /* Otherwise, add a REG_LABEL note for LABEL unless there already 3543 is one. */ 3544 else if (! find_reg_note (insn, REG_LABEL, label)) 3545 { 3546 /* This code used to ignore labels which refered to dispatch 3547 tables to avoid flow.c generating worse code. 3548 3549 However, in the presense of global optimizations like 3550 gcse which call find_basic_blocks without calling 3551 life_analysis, not recording such labels will lead 3552 to compiler aborts because of inconsistencies in the 3553 flow graph. So we go ahead and record the label. 3554 3555 It may also be the case that the optimization argument 3556 is no longer valid because of the more accurate cfg 3557 we build in find_basic_blocks -- it no longer pessimizes 3558 code when it finds a REG_LABEL note. */ 3559 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label, 3560 REG_NOTES (insn)); 3561 } 3562 } 3563 return; 3564 } 3565 3566 /* Do walk the labels in a vector, but not the first operand of an 3567 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */ 3568 case ADDR_VEC: 3569 case ADDR_DIFF_VEC: 3570 if (! INSN_DELETED_P (insn)) 3571 { 3572 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0; 3573 3574 for (i = 0; i < XVECLEN (x, eltnum); i++) 3575 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump); 3576 } 3577 return; 3578 3579 default: 3580 break; 3581 } 3582 3583 fmt = GET_RTX_FORMAT (code); 3584 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 3585 { 3586 if (fmt[i] == 'e') 3587 mark_jump_label (XEXP (x, i), insn, cross_jump); 3588 else if (fmt[i] == 'E') 3589 { 3590 register int j; 3591 for (j = 0; j < XVECLEN (x, i); j++) 3592 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump); 3593 } 3594 } 3595} 3596 3597/* If all INSN does is set the pc, delete it, 3598 and delete the insn that set the condition codes for it 3599 if that's what the previous thing was. */ 3600 3601void 3602delete_jump (insn) 3603 rtx insn; 3604{ 3605 register rtx set = single_set (insn); 3606 3607 if (set && GET_CODE (SET_DEST (set)) == PC) 3608 delete_computation (insn); 3609} 3610 3611/* Delete INSN and recursively delete insns that compute values used only 3612 by INSN. This uses the REG_DEAD notes computed during flow analysis. 3613 If we are running before flow.c, we need do nothing since flow.c will 3614 delete dead code. We also can't know if the registers being used are 3615 dead or not at this point. 3616 3617 Otherwise, look at all our REG_DEAD notes. If a previous insn does 3618 nothing other than set a register that dies in this insn, we can delete 3619 that insn as well. 3620 3621 On machines with CC0, if CC0 is used in this insn, we may be able to 3622 delete the insn that set it. */ 3623 3624static void 3625delete_computation (insn) 3626 rtx insn; 3627{ 3628 rtx note, next; 3629 3630#ifdef HAVE_cc0 3631 if (reg_referenced_p (cc0_rtx, PATTERN (insn))) 3632 { 3633 rtx prev = prev_nonnote_insn (insn); 3634 /* We assume that at this stage 3635 CC's are always set explicitly 3636 and always immediately before the jump that 3637 will use them. So if the previous insn 3638 exists to set the CC's, delete it 3639 (unless it performs auto-increments, etc.). */ 3640 if (prev && GET_CODE (prev) == INSN 3641 && sets_cc0_p (PATTERN (prev))) 3642 { 3643 if (sets_cc0_p (PATTERN (prev)) > 0 3644 && !FIND_REG_INC_NOTE (prev, NULL_RTX)) 3645 delete_computation (prev); 3646 else 3647 /* Otherwise, show that cc0 won't be used. */ 3648 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED, 3649 cc0_rtx, REG_NOTES (prev)); 3650 } 3651 } 3652#endif 3653 3654#ifdef INSN_SCHEDULING 3655 /* ?!? The schedulers do not keep REG_DEAD notes accurate after 3656 reload has completed. The schedulers need to be fixed. Until 3657 they are, we must not rely on the death notes here. */ 3658 if (reload_completed && flag_schedule_insns_after_reload) 3659 { 3660 delete_insn (insn); 3661 return; 3662 } 3663#endif 3664 3665 for (note = REG_NOTES (insn); note; note = next) 3666 { 3667 rtx our_prev; 3668 3669 next = XEXP (note, 1); 3670 3671 if (REG_NOTE_KIND (note) != REG_DEAD 3672 /* Verify that the REG_NOTE is legitimate. */ 3673 || GET_CODE (XEXP (note, 0)) != REG) 3674 continue; 3675 3676 for (our_prev = prev_nonnote_insn (insn); 3677 our_prev && GET_CODE (our_prev) == INSN; 3678 our_prev = prev_nonnote_insn (our_prev)) 3679 { 3680 /* If we reach a SEQUENCE, it is too complex to try to 3681 do anything with it, so give up. */ 3682 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE) 3683 break; 3684 3685 if (GET_CODE (PATTERN (our_prev)) == USE 3686 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN) 3687 /* reorg creates USEs that look like this. We leave them 3688 alone because reorg needs them for its own purposes. */ 3689 break; 3690 3691 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev))) 3692 { 3693 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX)) 3694 break; 3695 3696 if (GET_CODE (PATTERN (our_prev)) == PARALLEL) 3697 { 3698 /* If we find a SET of something else, we can't 3699 delete the insn. */ 3700 3701 int i; 3702 3703 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++) 3704 { 3705 rtx part = XVECEXP (PATTERN (our_prev), 0, i); 3706 3707 if (GET_CODE (part) == SET 3708 && SET_DEST (part) != XEXP (note, 0)) 3709 break; 3710 } 3711 3712 if (i == XVECLEN (PATTERN (our_prev), 0)) 3713 delete_computation (our_prev); 3714 } 3715 else if (GET_CODE (PATTERN (our_prev)) == SET 3716 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0)) 3717 delete_computation (our_prev); 3718 3719 break; 3720 } 3721 3722 /* If OUR_PREV references the register that dies here, it is an 3723 additional use. Hence any prior SET isn't dead. However, this 3724 insn becomes the new place for the REG_DEAD note. */ 3725 if (reg_overlap_mentioned_p (XEXP (note, 0), 3726 PATTERN (our_prev))) 3727 { 3728 XEXP (note, 1) = REG_NOTES (our_prev); 3729 REG_NOTES (our_prev) = note; 3730 break; 3731 } 3732 } 3733 } 3734 3735 delete_insn (insn); 3736} 3737 3738/* Delete insn INSN from the chain of insns and update label ref counts. 3739 May delete some following insns as a consequence; may even delete 3740 a label elsewhere and insns that follow it. 3741 3742 Returns the first insn after INSN that was not deleted. */ 3743 3744rtx 3745delete_insn (insn) 3746 register rtx insn; 3747{ 3748 register rtx next = NEXT_INSN (insn); 3749 register rtx prev = PREV_INSN (insn); 3750 register int was_code_label = (GET_CODE (insn) == CODE_LABEL); 3751 register int dont_really_delete = 0; 3752 3753 while (next && INSN_DELETED_P (next)) 3754 next = NEXT_INSN (next); 3755 3756 /* This insn is already deleted => return first following nondeleted. */ 3757 if (INSN_DELETED_P (insn)) 3758 return next; 3759 3760 /* Don't delete user-declared labels. Convert them to special NOTEs 3761 instead. */ 3762 if (was_code_label && LABEL_NAME (insn) != 0 3763 && optimize && ! dont_really_delete) 3764 { 3765 PUT_CODE (insn, NOTE); 3766 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL; 3767 NOTE_SOURCE_FILE (insn) = 0; 3768 dont_really_delete = 1; 3769 } 3770 else 3771 /* Mark this insn as deleted. */ 3772 INSN_DELETED_P (insn) = 1; 3773 3774 /* If this is an unconditional jump, delete it from the jump chain. */ 3775 if (simplejump_p (insn)) 3776 delete_from_jump_chain (insn); 3777 3778 /* If instruction is followed by a barrier, 3779 delete the barrier too. */ 3780 3781 if (next != 0 && GET_CODE (next) == BARRIER) 3782 { 3783 INSN_DELETED_P (next) = 1; 3784 next = NEXT_INSN (next); 3785 } 3786 3787 /* Patch out INSN (and the barrier if any) */ 3788 3789 if (optimize && ! dont_really_delete) 3790 { 3791 if (prev) 3792 { 3793 NEXT_INSN (prev) = next; 3794 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE) 3795 NEXT_INSN (XVECEXP (PATTERN (prev), 0, 3796 XVECLEN (PATTERN (prev), 0) - 1)) = next; 3797 } 3798 3799 if (next) 3800 { 3801 PREV_INSN (next) = prev; 3802 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE) 3803 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev; 3804 } 3805 3806 if (prev && NEXT_INSN (prev) == 0) 3807 set_last_insn (prev); 3808 } 3809 3810 /* If deleting a jump, decrement the count of the label, 3811 and delete the label if it is now unused. */ 3812 3813 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn)) 3814 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0) 3815 { 3816 /* This can delete NEXT or PREV, 3817 either directly if NEXT is JUMP_LABEL (INSN), 3818 or indirectly through more levels of jumps. */ 3819 delete_insn (JUMP_LABEL (insn)); 3820 /* I feel a little doubtful about this loop, 3821 but I see no clean and sure alternative way 3822 to find the first insn after INSN that is not now deleted. 3823 I hope this works. */ 3824 while (next && INSN_DELETED_P (next)) 3825 next = NEXT_INSN (next); 3826 return next; 3827 } 3828 3829 /* Likewise if we're deleting a dispatch table. */ 3830 3831 if (GET_CODE (insn) == JUMP_INSN 3832 && (GET_CODE (PATTERN (insn)) == ADDR_VEC 3833 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)) 3834 { 3835 rtx pat = PATTERN (insn); 3836 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC; 3837 int len = XVECLEN (pat, diff_vec_p); 3838 3839 for (i = 0; i < len; i++) 3840 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0) 3841 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0)); 3842 while (next && INSN_DELETED_P (next)) 3843 next = NEXT_INSN (next); 3844 return next; 3845 } 3846 3847 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE)) 3848 prev = PREV_INSN (prev); 3849 3850 /* If INSN was a label and a dispatch table follows it, 3851 delete the dispatch table. The tablejump must have gone already. 3852 It isn't useful to fall through into a table. */ 3853 3854 if (was_code_label 3855 && NEXT_INSN (insn) != 0 3856 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN 3857 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC 3858 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC)) 3859 next = delete_insn (NEXT_INSN (insn)); 3860 3861 /* If INSN was a label, delete insns following it if now unreachable. */ 3862 3863 if (was_code_label && prev && GET_CODE (prev) == BARRIER) 3864 { 3865 register RTX_CODE code; 3866 while (next != 0 3867 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i' 3868 || code == NOTE || code == BARRIER 3869 || (code == CODE_LABEL && INSN_DELETED_P (next)))) 3870 { 3871 if (code == NOTE 3872 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END) 3873 next = NEXT_INSN (next); 3874 /* Keep going past other deleted labels to delete what follows. */ 3875 else if (code == CODE_LABEL && INSN_DELETED_P (next)) 3876 next = NEXT_INSN (next); 3877 else 3878 /* Note: if this deletes a jump, it can cause more 3879 deletion of unreachable code, after a different label. 3880 As long as the value from this recursive call is correct, 3881 this invocation functions correctly. */ 3882 next = delete_insn (next); 3883 } 3884 } 3885 3886 return next; 3887} 3888 3889/* Advance from INSN till reaching something not deleted 3890 then return that. May return INSN itself. */ 3891 3892rtx 3893next_nondeleted_insn (insn) 3894 rtx insn; 3895{ 3896 while (INSN_DELETED_P (insn)) 3897 insn = NEXT_INSN (insn); 3898 return insn; 3899} 3900 3901/* Delete a range of insns from FROM to TO, inclusive. 3902 This is for the sake of peephole optimization, so assume 3903 that whatever these insns do will still be done by a new 3904 peephole insn that will replace them. */ 3905 3906void 3907delete_for_peephole (from, to) 3908 register rtx from, to; 3909{ 3910 register rtx insn = from; 3911 3912 while (1) 3913 { 3914 register rtx next = NEXT_INSN (insn); 3915 register rtx prev = PREV_INSN (insn); 3916 3917 if (GET_CODE (insn) != NOTE) 3918 { 3919 INSN_DELETED_P (insn) = 1; 3920 3921 /* Patch this insn out of the chain. */ 3922 /* We don't do this all at once, because we 3923 must preserve all NOTEs. */ 3924 if (prev) 3925 NEXT_INSN (prev) = next; 3926 3927 if (next) 3928 PREV_INSN (next) = prev; 3929 } 3930 3931 if (insn == to) 3932 break; 3933 insn = next; 3934 } 3935 3936 /* Note that if TO is an unconditional jump 3937 we *do not* delete the BARRIER that follows, 3938 since the peephole that replaces this sequence 3939 is also an unconditional jump in that case. */ 3940} 3941 3942/* Invert the condition of the jump JUMP, and make it jump 3943 to label NLABEL instead of where it jumps now. */ 3944 3945int 3946invert_jump (jump, nlabel) 3947 rtx jump, nlabel; 3948{ 3949 /* We have to either invert the condition and change the label or 3950 do neither. Either operation could fail. We first try to invert 3951 the jump. If that succeeds, we try changing the label. If that fails, 3952 we invert the jump back to what it was. */ 3953 3954 if (! invert_exp (PATTERN (jump), jump)) 3955 return 0; 3956 3957 if (redirect_jump (jump, nlabel)) 3958 { 3959 if (flag_branch_probabilities) 3960 { 3961 rtx note = find_reg_note (jump, REG_BR_PROB, 0); 3962 3963 /* An inverted jump means that a probability taken becomes a 3964 probability not taken. Subtract the branch probability from the 3965 probability base to convert it back to a taken probability. 3966 (We don't flip the probability on a branch that's never taken. */ 3967 if (note && XINT (XEXP (note, 0), 0) >= 0) 3968 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0); 3969 } 3970 3971 return 1; 3972 } 3973 3974 if (! invert_exp (PATTERN (jump), jump)) 3975 /* This should just be putting it back the way it was. */ 3976 abort (); 3977 3978 return 0; 3979} 3980 3981/* Invert the jump condition of rtx X contained in jump insn, INSN. 3982 3983 Return 1 if we can do so, 0 if we cannot find a way to do so that 3984 matches a pattern. */ 3985 3986int 3987invert_exp (x, insn) 3988 rtx x; 3989 rtx insn; 3990{ 3991 register RTX_CODE code; 3992 register int i; 3993 register char *fmt; 3994 3995 code = GET_CODE (x); 3996 3997 if (code == IF_THEN_ELSE) 3998 { 3999 register rtx comp = XEXP (x, 0); 4000 register rtx tem; 4001 4002 /* We can do this in two ways: The preferable way, which can only 4003 be done if this is not an integer comparison, is to reverse 4004 the comparison code. Otherwise, swap the THEN-part and ELSE-part 4005 of the IF_THEN_ELSE. If we can't do either, fail. */ 4006 4007 if (can_reverse_comparison_p (comp, insn) 4008 && validate_change (insn, &XEXP (x, 0), 4009 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)), 4010 GET_MODE (comp), XEXP (comp, 0), 4011 XEXP (comp, 1)), 0)) 4012 return 1; 4013 4014 tem = XEXP (x, 1); 4015 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1); 4016 validate_change (insn, &XEXP (x, 2), tem, 1); 4017 return apply_change_group (); 4018 } 4019 4020 fmt = GET_RTX_FORMAT (code); 4021 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 4022 { 4023 if (fmt[i] == 'e') 4024 if (! invert_exp (XEXP (x, i), insn)) 4025 return 0; 4026 if (fmt[i] == 'E') 4027 { 4028 register int j; 4029 for (j = 0; j < XVECLEN (x, i); j++) 4030 if (!invert_exp (XVECEXP (x, i, j), insn)) 4031 return 0; 4032 } 4033 } 4034 4035 return 1; 4036} 4037 4038/* Make jump JUMP jump to label NLABEL instead of where it jumps now. 4039 If the old jump target label is unused as a result, 4040 it and the code following it may be deleted. 4041 4042 If NLABEL is zero, we are to turn the jump into a (possibly conditional) 4043 RETURN insn. 4044 4045 The return value will be 1 if the change was made, 0 if it wasn't (this 4046 can only occur for NLABEL == 0). */ 4047 4048int 4049redirect_jump (jump, nlabel) 4050 rtx jump, nlabel; 4051{ 4052 register rtx olabel = JUMP_LABEL (jump); 4053 4054 if (nlabel == olabel) 4055 return 1; 4056 4057 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump)) 4058 return 0; 4059 4060 /* If this is an unconditional branch, delete it from the jump_chain of 4061 OLABEL and add it to the jump_chain of NLABEL (assuming both labels 4062 have UID's in range and JUMP_CHAIN is valid). */ 4063 if (jump_chain && (simplejump_p (jump) 4064 || GET_CODE (PATTERN (jump)) == RETURN)) 4065 { 4066 int label_index = nlabel ? INSN_UID (nlabel) : 0; 4067 4068 delete_from_jump_chain (jump); 4069 if (label_index < max_jump_chain 4070 && INSN_UID (jump) < max_jump_chain) 4071 { 4072 jump_chain[INSN_UID (jump)] = jump_chain[label_index]; 4073 jump_chain[label_index] = jump; 4074 } 4075 } 4076 4077 JUMP_LABEL (jump) = nlabel; 4078 if (nlabel) 4079 ++LABEL_NUSES (nlabel); 4080 4081 if (olabel && --LABEL_NUSES (olabel) == 0) 4082 delete_insn (olabel); 4083 4084 return 1; 4085} 4086 4087/* Delete the instruction JUMP from any jump chain it might be on. */ 4088 4089static void 4090delete_from_jump_chain (jump) 4091 rtx jump; 4092{ 4093 int index; 4094 rtx olabel = JUMP_LABEL (jump); 4095 4096 /* Handle unconditional jumps. */ 4097 if (jump_chain && olabel != 0 4098 && INSN_UID (olabel) < max_jump_chain 4099 && simplejump_p (jump)) 4100 index = INSN_UID (olabel); 4101 /* Handle return insns. */ 4102 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN) 4103 index = 0; 4104 else return; 4105 4106 if (jump_chain[index] == jump) 4107 jump_chain[index] = jump_chain[INSN_UID (jump)]; 4108 else 4109 { 4110 rtx insn; 4111 4112 for (insn = jump_chain[index]; 4113 insn != 0; 4114 insn = jump_chain[INSN_UID (insn)]) 4115 if (jump_chain[INSN_UID (insn)] == jump) 4116 { 4117 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)]; 4118 break; 4119 } 4120 } 4121} 4122 4123/* If NLABEL is nonzero, throughout the rtx at LOC, 4124 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is 4125 zero, alter (RETURN) to (LABEL_REF NLABEL). 4126 4127 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check 4128 validity with validate_change. Convert (set (pc) (label_ref olabel)) 4129 to (return). 4130 4131 Return 0 if we found a change we would like to make but it is invalid. 4132 Otherwise, return 1. */ 4133 4134int 4135redirect_exp (loc, olabel, nlabel, insn) 4136 rtx *loc; 4137 rtx olabel, nlabel; 4138 rtx insn; 4139{ 4140 register rtx x = *loc; 4141 register RTX_CODE code = GET_CODE (x); 4142 register int i; 4143 register char *fmt; 4144 4145 if (code == LABEL_REF) 4146 { 4147 if (XEXP (x, 0) == olabel) 4148 { 4149 if (nlabel) 4150 XEXP (x, 0) = nlabel; 4151 else 4152 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0); 4153 return 1; 4154 } 4155 } 4156 else if (code == RETURN && olabel == 0) 4157 { 4158 x = gen_rtx_LABEL_REF (VOIDmode, nlabel); 4159 if (loc == &PATTERN (insn)) 4160 x = gen_rtx_SET (VOIDmode, pc_rtx, x); 4161 return validate_change (insn, loc, x, 0); 4162 } 4163 4164 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx 4165 && GET_CODE (SET_SRC (x)) == LABEL_REF 4166 && XEXP (SET_SRC (x), 0) == olabel) 4167 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0); 4168 4169 fmt = GET_RTX_FORMAT (code); 4170 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 4171 { 4172 if (fmt[i] == 'e') 4173 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn)) 4174 return 0; 4175 if (fmt[i] == 'E') 4176 { 4177 register int j; 4178 for (j = 0; j < XVECLEN (x, i); j++) 4179 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn)) 4180 return 0; 4181 } 4182 } 4183 4184 return 1; 4185} 4186 4187/* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump. 4188 4189 If the old jump target label (before the dispatch table) becomes unused, 4190 it and the dispatch table may be deleted. In that case, find the insn 4191 before the jump references that label and delete it and logical successors 4192 too. */ 4193 4194static void 4195redirect_tablejump (jump, nlabel) 4196 rtx jump, nlabel; 4197{ 4198 register rtx olabel = JUMP_LABEL (jump); 4199 4200 /* Add this jump to the jump_chain of NLABEL. */ 4201 if (jump_chain && INSN_UID (nlabel) < max_jump_chain 4202 && INSN_UID (jump) < max_jump_chain) 4203 { 4204 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)]; 4205 jump_chain[INSN_UID (nlabel)] = jump; 4206 } 4207 4208 PATTERN (jump) = gen_jump (nlabel); 4209 JUMP_LABEL (jump) = nlabel; 4210 ++LABEL_NUSES (nlabel); 4211 INSN_CODE (jump) = -1; 4212 4213 if (--LABEL_NUSES (olabel) == 0) 4214 { 4215 delete_labelref_insn (jump, olabel, 0); 4216 delete_insn (olabel); 4217 } 4218} 4219 4220/* Find the insn referencing LABEL that is a logical predecessor of INSN. 4221 If we found one, delete it and then delete this insn if DELETE_THIS is 4222 non-zero. Return non-zero if INSN or a predecessor references LABEL. */ 4223 4224static int 4225delete_labelref_insn (insn, label, delete_this) 4226 rtx insn, label; 4227 int delete_this; 4228{ 4229 int deleted = 0; 4230 rtx link; 4231 4232 if (GET_CODE (insn) != NOTE 4233 && reg_mentioned_p (label, PATTERN (insn))) 4234 { 4235 if (delete_this) 4236 { 4237 delete_insn (insn); 4238 deleted = 1; 4239 } 4240 else 4241 return 1; 4242 } 4243 4244 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1)) 4245 if (delete_labelref_insn (XEXP (link, 0), label, 1)) 4246 { 4247 if (delete_this) 4248 { 4249 delete_insn (insn); 4250 deleted = 1; 4251 } 4252 else 4253 return 1; 4254 } 4255 4256 return deleted; 4257} 4258 4259/* Like rtx_equal_p except that it considers two REGs as equal 4260 if they renumber to the same value and considers two commutative 4261 operations to be the same if the order of the operands has been 4262 reversed. */ 4263 4264int 4265rtx_renumbered_equal_p (x, y) 4266 rtx x, y; 4267{ 4268 register int i; 4269 register RTX_CODE code = GET_CODE (x); 4270 register char *fmt; 4271 4272 if (x == y) 4273 return 1; 4274 4275 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG)) 4276 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG 4277 && GET_CODE (SUBREG_REG (y)) == REG))) 4278 { 4279 int reg_x = -1, reg_y = -1; 4280 int word_x = 0, word_y = 0; 4281 4282 if (GET_MODE (x) != GET_MODE (y)) 4283 return 0; 4284 4285 /* If we haven't done any renumbering, don't 4286 make any assumptions. */ 4287 if (reg_renumber == 0) 4288 return rtx_equal_p (x, y); 4289 4290 if (code == SUBREG) 4291 { 4292 reg_x = REGNO (SUBREG_REG (x)); 4293 word_x = SUBREG_WORD (x); 4294 4295 if (reg_renumber[reg_x] >= 0) 4296 { 4297 reg_x = reg_renumber[reg_x] + word_x; 4298 word_x = 0; 4299 } 4300 } 4301 4302 else 4303 { 4304 reg_x = REGNO (x); 4305 if (reg_renumber[reg_x] >= 0) 4306 reg_x = reg_renumber[reg_x]; 4307 } 4308 4309 if (GET_CODE (y) == SUBREG) 4310 { 4311 reg_y = REGNO (SUBREG_REG (y)); 4312 word_y = SUBREG_WORD (y); 4313 4314 if (reg_renumber[reg_y] >= 0) 4315 { 4316 reg_y = reg_renumber[reg_y]; 4317 word_y = 0; 4318 } 4319 } 4320 4321 else 4322 { 4323 reg_y = REGNO (y); 4324 if (reg_renumber[reg_y] >= 0) 4325 reg_y = reg_renumber[reg_y]; 4326 } 4327 4328 return reg_x >= 0 && reg_x == reg_y && word_x == word_y; 4329 } 4330 4331 /* Now we have disposed of all the cases 4332 in which different rtx codes can match. */ 4333 if (code != GET_CODE (y)) 4334 return 0; 4335 4336 switch (code) 4337 { 4338 case PC: 4339 case CC0: 4340 case ADDR_VEC: 4341 case ADDR_DIFF_VEC: 4342 return 0; 4343 4344 case CONST_INT: 4345 return INTVAL (x) == INTVAL (y); 4346 4347 case LABEL_REF: 4348 /* We can't assume nonlocal labels have their following insns yet. */ 4349 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y)) 4350 return XEXP (x, 0) == XEXP (y, 0); 4351 4352 /* Two label-refs are equivalent if they point at labels 4353 in the same position in the instruction stream. */ 4354 return (next_real_insn (XEXP (x, 0)) 4355 == next_real_insn (XEXP (y, 0))); 4356 4357 case SYMBOL_REF: 4358 return XSTR (x, 0) == XSTR (y, 0); 4359 4360 case CODE_LABEL: 4361 /* If we didn't match EQ equality above, they aren't the same. */ 4362 return 0; 4363 4364 default: 4365 break; 4366 } 4367 4368 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ 4369 4370 if (GET_MODE (x) != GET_MODE (y)) 4371 return 0; 4372 4373 /* For commutative operations, the RTX match if the operand match in any 4374 order. Also handle the simple binary and unary cases without a loop. */ 4375 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c') 4376 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0)) 4377 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1))) 4378 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1)) 4379 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0)))); 4380 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2') 4381 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0)) 4382 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1))); 4383 else if (GET_RTX_CLASS (code) == '1') 4384 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0)); 4385 4386 /* Compare the elements. If any pair of corresponding elements 4387 fail to match, return 0 for the whole things. */ 4388 4389 fmt = GET_RTX_FORMAT (code); 4390 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 4391 { 4392 register int j; 4393 switch (fmt[i]) 4394 { 4395 case 'w': 4396 if (XWINT (x, i) != XWINT (y, i)) 4397 return 0; 4398 break; 4399 4400 case 'i': 4401 if (XINT (x, i) != XINT (y, i)) 4402 return 0; 4403 break; 4404 4405 case 's': 4406 if (strcmp (XSTR (x, i), XSTR (y, i))) 4407 return 0; 4408 break; 4409 4410 case 'e': 4411 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i))) 4412 return 0; 4413 break; 4414 4415 case 'u': 4416 if (XEXP (x, i) != XEXP (y, i)) 4417 return 0; 4418 /* fall through. */ 4419 case '0': 4420 break; 4421 4422 case 'E': 4423 if (XVECLEN (x, i) != XVECLEN (y, i)) 4424 return 0; 4425 for (j = XVECLEN (x, i) - 1; j >= 0; j--) 4426 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j))) 4427 return 0; 4428 break; 4429 4430 default: 4431 abort (); 4432 } 4433 } 4434 return 1; 4435} 4436 4437/* If X is a hard register or equivalent to one or a subregister of one, 4438 return the hard register number. If X is a pseudo register that was not 4439 assigned a hard register, return the pseudo register number. Otherwise, 4440 return -1. Any rtx is valid for X. */ 4441 4442int 4443true_regnum (x) 4444 rtx x; 4445{ 4446 if (GET_CODE (x) == REG) 4447 { 4448 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0) 4449 return reg_renumber[REGNO (x)]; 4450 return REGNO (x); 4451 } 4452 if (GET_CODE (x) == SUBREG) 4453 { 4454 int base = true_regnum (SUBREG_REG (x)); 4455 if (base >= 0 && base < FIRST_PSEUDO_REGISTER) 4456 return SUBREG_WORD (x) + base; 4457 } 4458 return -1; 4459} 4460 4461/* Optimize code of the form: 4462 4463 for (x = a[i]; x; ...) 4464 ... 4465 for (x = a[i]; x; ...) 4466 ... 4467 foo: 4468 4469 Loop optimize will change the above code into 4470 4471 if (x = a[i]) 4472 for (;;) 4473 { ...; if (! (x = ...)) break; } 4474 if (x = a[i]) 4475 for (;;) 4476 { ...; if (! (x = ...)) break; } 4477 foo: 4478 4479 In general, if the first test fails, the program can branch 4480 directly to `foo' and skip the second try which is doomed to fail. 4481 We run this after loop optimization and before flow analysis. */ 4482 4483/* When comparing the insn patterns, we track the fact that different 4484 pseudo-register numbers may have been used in each computation. 4485 The following array stores an equivalence -- same_regs[I] == J means 4486 that pseudo register I was used in the first set of tests in a context 4487 where J was used in the second set. We also count the number of such 4488 pending equivalences. If nonzero, the expressions really aren't the 4489 same. */ 4490 4491static int *same_regs; 4492 4493static int num_same_regs; 4494 4495/* Track any registers modified between the target of the first jump and 4496 the second jump. They never compare equal. */ 4497 4498static char *modified_regs; 4499 4500/* Record if memory was modified. */ 4501 4502static int modified_mem; 4503 4504/* Called via note_stores on each insn between the target of the first 4505 branch and the second branch. It marks any changed registers. */ 4506 4507static void 4508mark_modified_reg (dest, x) 4509 rtx dest; 4510 rtx x ATTRIBUTE_UNUSED; 4511{ 4512 int regno, i; 4513 4514 if (GET_CODE (dest) == SUBREG) 4515 dest = SUBREG_REG (dest); 4516 4517 if (GET_CODE (dest) == MEM) 4518 modified_mem = 1; 4519 4520 if (GET_CODE (dest) != REG) 4521 return; 4522 4523 regno = REGNO (dest); 4524 if (regno >= FIRST_PSEUDO_REGISTER) 4525 modified_regs[regno] = 1; 4526 else 4527 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++) 4528 modified_regs[regno + i] = 1; 4529} 4530 4531/* F is the first insn in the chain of insns. */ 4532 4533void 4534thread_jumps (f, max_reg, flag_before_loop) 4535 rtx f; 4536 int max_reg; 4537 int flag_before_loop; 4538{ 4539 /* Basic algorithm is to find a conditional branch, 4540 the label it may branch to, and the branch after 4541 that label. If the two branches test the same condition, 4542 walk back from both branch paths until the insn patterns 4543 differ, or code labels are hit. If we make it back to 4544 the target of the first branch, then we know that the first branch 4545 will either always succeed or always fail depending on the relative 4546 senses of the two branches. So adjust the first branch accordingly 4547 in this case. */ 4548 4549 rtx label, b1, b2, t1, t2; 4550 enum rtx_code code1, code2; 4551 rtx b1op0, b1op1, b2op0, b2op1; 4552 int changed = 1; 4553 int i; 4554 int *all_reset; 4555 4556 /* Allocate register tables and quick-reset table. */ 4557 modified_regs = (char *) alloca (max_reg * sizeof (char)); 4558 same_regs = (int *) alloca (max_reg * sizeof (int)); 4559 all_reset = (int *) alloca (max_reg * sizeof (int)); 4560 for (i = 0; i < max_reg; i++) 4561 all_reset[i] = -1; 4562 4563 while (changed) 4564 { 4565 changed = 0; 4566 4567 for (b1 = f; b1; b1 = NEXT_INSN (b1)) 4568 { 4569 /* Get to a candidate branch insn. */ 4570 if (GET_CODE (b1) != JUMP_INSN 4571 || ! condjump_p (b1) || simplejump_p (b1) 4572 || JUMP_LABEL (b1) == 0) 4573 continue; 4574 4575 bzero (modified_regs, max_reg * sizeof (char)); 4576 modified_mem = 0; 4577 4578 bcopy ((char *) all_reset, (char *) same_regs, 4579 max_reg * sizeof (int)); 4580 num_same_regs = 0; 4581 4582 label = JUMP_LABEL (b1); 4583 4584 /* Look for a branch after the target. Record any registers and 4585 memory modified between the target and the branch. Stop when we 4586 get to a label since we can't know what was changed there. */ 4587 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2)) 4588 { 4589 if (GET_CODE (b2) == CODE_LABEL) 4590 break; 4591 4592 else if (GET_CODE (b2) == JUMP_INSN) 4593 { 4594 /* If this is an unconditional jump and is the only use of 4595 its target label, we can follow it. */ 4596 if (simplejump_p (b2) 4597 && JUMP_LABEL (b2) != 0 4598 && LABEL_NUSES (JUMP_LABEL (b2)) == 1) 4599 { 4600 b2 = JUMP_LABEL (b2); 4601 continue; 4602 } 4603 else 4604 break; 4605 } 4606 4607 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN) 4608 continue; 4609 4610 if (GET_CODE (b2) == CALL_INSN) 4611 { 4612 modified_mem = 1; 4613 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 4614 if (call_used_regs[i] && ! fixed_regs[i] 4615 && i != STACK_POINTER_REGNUM 4616 && i != FRAME_POINTER_REGNUM 4617 && i != HARD_FRAME_POINTER_REGNUM 4618 && i != ARG_POINTER_REGNUM) 4619 modified_regs[i] = 1; 4620 } 4621 4622 note_stores (PATTERN (b2), mark_modified_reg); 4623 } 4624 4625 /* Check the next candidate branch insn from the label 4626 of the first. */ 4627 if (b2 == 0 4628 || GET_CODE (b2) != JUMP_INSN 4629 || b2 == b1 4630 || ! condjump_p (b2) 4631 || simplejump_p (b2)) 4632 continue; 4633 4634 /* Get the comparison codes and operands, reversing the 4635 codes if appropriate. If we don't have comparison codes, 4636 we can't do anything. */ 4637 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0); 4638 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1); 4639 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0)); 4640 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx) 4641 code1 = reverse_condition (code1); 4642 4643 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0); 4644 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1); 4645 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0)); 4646 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx) 4647 code2 = reverse_condition (code2); 4648 4649 /* If they test the same things and knowing that B1 branches 4650 tells us whether or not B2 branches, check if we 4651 can thread the branch. */ 4652 if (rtx_equal_for_thread_p (b1op0, b2op0, b2) 4653 && rtx_equal_for_thread_p (b1op1, b2op1, b2) 4654 && (comparison_dominates_p (code1, code2) 4655 || (comparison_dominates_p (code1, reverse_condition (code2)) 4656 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)), 4657 0), 4658 b1)))) 4659 { 4660 t1 = prev_nonnote_insn (b1); 4661 t2 = prev_nonnote_insn (b2); 4662 4663 while (t1 != 0 && t2 != 0) 4664 { 4665 if (t2 == label) 4666 { 4667 /* We have reached the target of the first branch. 4668 If there are no pending register equivalents, 4669 we know that this branch will either always 4670 succeed (if the senses of the two branches are 4671 the same) or always fail (if not). */ 4672 rtx new_label; 4673 4674 if (num_same_regs != 0) 4675 break; 4676 4677 if (comparison_dominates_p (code1, code2)) 4678 new_label = JUMP_LABEL (b2); 4679 else 4680 new_label = get_label_after (b2); 4681 4682 if (JUMP_LABEL (b1) != new_label) 4683 { 4684 rtx prev = PREV_INSN (new_label); 4685 4686 if (flag_before_loop 4687 && GET_CODE (prev) == NOTE 4688 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG) 4689 { 4690 /* Don't thread to the loop label. If a loop 4691 label is reused, loop optimization will 4692 be disabled for that loop. */ 4693 new_label = gen_label_rtx (); 4694 emit_label_after (new_label, PREV_INSN (prev)); 4695 } 4696 changed |= redirect_jump (b1, new_label); 4697 } 4698 break; 4699 } 4700 4701 /* If either of these is not a normal insn (it might be 4702 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs 4703 have already been skipped above.) Similarly, fail 4704 if the insns are different. */ 4705 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN 4706 || recog_memoized (t1) != recog_memoized (t2) 4707 || ! rtx_equal_for_thread_p (PATTERN (t1), 4708 PATTERN (t2), t2)) 4709 break; 4710 4711 t1 = prev_nonnote_insn (t1); 4712 t2 = prev_nonnote_insn (t2); 4713 } 4714 } 4715 } 4716 } 4717} 4718 4719/* This is like RTX_EQUAL_P except that it knows about our handling of 4720 possibly equivalent registers and knows to consider volatile and 4721 modified objects as not equal. 4722 4723 YINSN is the insn containing Y. */ 4724 4725int 4726rtx_equal_for_thread_p (x, y, yinsn) 4727 rtx x, y; 4728 rtx yinsn; 4729{ 4730 register int i; 4731 register int j; 4732 register enum rtx_code code; 4733 register char *fmt; 4734 4735 code = GET_CODE (x); 4736 /* Rtx's of different codes cannot be equal. */ 4737 if (code != GET_CODE (y)) 4738 return 0; 4739 4740 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. 4741 (REG:SI x) and (REG:HI x) are NOT equivalent. */ 4742 4743 if (GET_MODE (x) != GET_MODE (y)) 4744 return 0; 4745 4746 /* For floating-point, consider everything unequal. This is a bit 4747 pessimistic, but this pass would only rarely do anything for FP 4748 anyway. */ 4749 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT 4750 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math) 4751 return 0; 4752 4753 /* For commutative operations, the RTX match if the operand match in any 4754 order. Also handle the simple binary and unary cases without a loop. */ 4755 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c') 4756 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn) 4757 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn)) 4758 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn) 4759 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn))); 4760 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2') 4761 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn) 4762 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn)); 4763 else if (GET_RTX_CLASS (code) == '1') 4764 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn); 4765 4766 /* Handle special-cases first. */ 4767 switch (code) 4768 { 4769 case REG: 4770 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)]) 4771 return 1; 4772 4773 /* If neither is user variable or hard register, check for possible 4774 equivalence. */ 4775 if (REG_USERVAR_P (x) || REG_USERVAR_P (y) 4776 || REGNO (x) < FIRST_PSEUDO_REGISTER 4777 || REGNO (y) < FIRST_PSEUDO_REGISTER) 4778 return 0; 4779 4780 if (same_regs[REGNO (x)] == -1) 4781 { 4782 same_regs[REGNO (x)] = REGNO (y); 4783 num_same_regs++; 4784 4785 /* If this is the first time we are seeing a register on the `Y' 4786 side, see if it is the last use. If not, we can't thread the 4787 jump, so mark it as not equivalent. */ 4788 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn)) 4789 return 0; 4790 4791 return 1; 4792 } 4793 else 4794 return (same_regs[REGNO (x)] == REGNO (y)); 4795 4796 break; 4797 4798 case MEM: 4799 /* If memory modified or either volatile, not equivalent. 4800 Else, check address. */ 4801 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y)) 4802 return 0; 4803 4804 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn); 4805 4806 case ASM_INPUT: 4807 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y)) 4808 return 0; 4809 4810 break; 4811 4812 case SET: 4813 /* Cancel a pending `same_regs' if setting equivalenced registers. 4814 Then process source. */ 4815 if (GET_CODE (SET_DEST (x)) == REG 4816 && GET_CODE (SET_DEST (y)) == REG) 4817 { 4818 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y))) 4819 { 4820 same_regs[REGNO (SET_DEST (x))] = -1; 4821 num_same_regs--; 4822 } 4823 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y))) 4824 return 0; 4825 } 4826 else 4827 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0) 4828 return 0; 4829 4830 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn); 4831 4832 case LABEL_REF: 4833 return XEXP (x, 0) == XEXP (y, 0); 4834 4835 case SYMBOL_REF: 4836 return XSTR (x, 0) == XSTR (y, 0); 4837 4838 default: 4839 break; 4840 } 4841 4842 if (x == y) 4843 return 1; 4844 4845 fmt = GET_RTX_FORMAT (code); 4846 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 4847 { 4848 switch (fmt[i]) 4849 { 4850 case 'w': 4851 if (XWINT (x, i) != XWINT (y, i)) 4852 return 0; 4853 break; 4854 4855 case 'n': 4856 case 'i': 4857 if (XINT (x, i) != XINT (y, i)) 4858 return 0; 4859 break; 4860 4861 case 'V': 4862 case 'E': 4863 /* Two vectors must have the same length. */ 4864 if (XVECLEN (x, i) != XVECLEN (y, i)) 4865 return 0; 4866 4867 /* And the corresponding elements must match. */ 4868 for (j = 0; j < XVECLEN (x, i); j++) 4869 if (rtx_equal_for_thread_p (XVECEXP (x, i, j), 4870 XVECEXP (y, i, j), yinsn) == 0) 4871 return 0; 4872 break; 4873 4874 case 'e': 4875 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0) 4876 return 0; 4877 break; 4878 4879 case 'S': 4880 case 's': 4881 if (strcmp (XSTR (x, i), XSTR (y, i))) 4882 return 0; 4883 break; 4884 4885 case 'u': 4886 /* These are just backpointers, so they don't matter. */ 4887 break; 4888 4889 case '0': 4890 break; 4891 4892 /* It is believed that rtx's at this level will never 4893 contain anything but integers and other rtx's, 4894 except for within LABEL_REFs and SYMBOL_REFs. */ 4895 default: 4896 abort (); 4897 } 4898 } 4899 return 1; 4900} 4901 4902 4903#ifndef HAVE_cc0 4904/* Return the insn that NEW can be safely inserted in front of starting at 4905 the jump insn INSN. Return 0 if it is not safe to do this jump 4906 optimization. Note that NEW must contain a single set. */ 4907 4908static rtx 4909find_insert_position (insn, new) 4910 rtx insn; 4911 rtx new; 4912{ 4913 int i; 4914 rtx prev; 4915 4916 /* If NEW does not clobber, it is safe to insert NEW before INSN. */ 4917 if (GET_CODE (PATTERN (new)) != PARALLEL) 4918 return insn; 4919 4920 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--) 4921 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER 4922 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0), 4923 insn)) 4924 break; 4925 4926 if (i < 0) 4927 return insn; 4928 4929 /* There is a good chance that the previous insn PREV sets the thing 4930 being clobbered (often the CC in a hard reg). If PREV does not 4931 use what NEW sets, we can insert NEW before PREV. */ 4932 4933 prev = prev_active_insn (insn); 4934 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--) 4935 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER 4936 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0), 4937 insn) 4938 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0), 4939 prev)) 4940 return 0; 4941 4942 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev; 4943} 4944#endif /* !HAVE_cc0 */ 4945