1 /* Copy propagation on hard registers for the GNU compiler. 2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 3 2010 Free Software Foundation, Inc. 4 5 This file is part of GCC. 6 7 GCC is free software; you can redistribute it and/or modify it 8 under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3, or (at your option) 10 any later version. 11 12 GCC is distributed in the hope that it will be useful, but WITHOUT 13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public 15 License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with GCC; see the file COPYING3. If not see 19 <http://www.gnu.org/licenses/>. */ 20 21 #include "config.h" 22 #include "system.h" 23 #include "coretypes.h" 24 #include "tm.h" 25 #include "rtl.h" 26 #include "tm_p.h" 27 #include "insn-config.h" 28 #include "regs.h" 29 #include "addresses.h" 30 #include "hard-reg-set.h" 31 #include "basic-block.h" 32 #include "reload.h" 33 #include "output.h" 34 #include "function.h" 35 #include "recog.h" 36 #include "flags.h" 37 #include "diagnostic-core.h" 38 #include "obstack.h" 39 #include "timevar.h" 40 #include "tree-pass.h" 41 #include "df.h" 42 43 /* The following code does forward propagation of hard register copies. 44 The object is to eliminate as many dependencies as possible, so that 45 we have the most scheduling freedom. As a side effect, we also clean 46 up some silly register allocation decisions made by reload. This 47 code may be obsoleted by a new register allocator. */ 48 49 /* DEBUG_INSNs aren't changed right away, as doing so might extend the 50 lifetime of a register and get the DEBUG_INSN subsequently reset. 51 So they are queued instead, and updated only when the register is 52 used in some subsequent real insn before it is set. */ 53 struct queued_debug_insn_change 54 { 55 struct queued_debug_insn_change *next; 56 rtx insn; 57 rtx *loc; 58 rtx new_rtx; 59 }; 60 61 /* For each register, we have a list of registers that contain the same 62 value. The OLDEST_REGNO field points to the head of the list, and 63 the NEXT_REGNO field runs through the list. The MODE field indicates 64 what mode the data is known to be in; this field is VOIDmode when the 65 register is not known to contain valid data. */ 66 67 struct value_data_entry 68 { 69 enum machine_mode mode; 70 unsigned int oldest_regno; 71 unsigned int next_regno; 72 struct queued_debug_insn_change *debug_insn_changes; 73 }; 74 75 struct value_data 76 { 77 struct value_data_entry e[FIRST_PSEUDO_REGISTER]; 78 unsigned int max_value_regs; 79 unsigned int n_debug_insn_changes; 80 }; 81 82 static alloc_pool debug_insn_changes_pool; 83 84 static void kill_value_one_regno (unsigned, struct value_data *); 85 static void kill_value_regno (unsigned, unsigned, struct value_data *); 86 static void kill_value (rtx, struct value_data *); 87 static void set_value_regno (unsigned, enum machine_mode, struct value_data *); 88 static void init_value_data (struct value_data *); 89 static void kill_clobbered_value (rtx, const_rtx, void *); 90 static void kill_set_value (rtx, const_rtx, void *); 91 static int kill_autoinc_value (rtx *, void *); 92 static void copy_value (rtx, rtx, struct value_data *); 93 static bool mode_change_ok (enum machine_mode, enum machine_mode, 94 unsigned int); 95 static rtx maybe_mode_change (enum machine_mode, enum machine_mode, 96 enum machine_mode, unsigned int, unsigned int); 97 static rtx find_oldest_value_reg (enum reg_class, rtx, struct value_data *); 98 static bool replace_oldest_value_reg (rtx *, enum reg_class, rtx, 99 struct value_data *); 100 static bool replace_oldest_value_addr (rtx *, enum reg_class, 101 enum machine_mode, addr_space_t, rtx, 102 struct value_data *); 103 static bool replace_oldest_value_mem (rtx, rtx, struct value_data *); 104 static bool copyprop_hardreg_forward_1 (basic_block, struct value_data *); 105 extern void debug_value_data (struct value_data *); 106 #ifdef ENABLE_CHECKING 107 static void validate_value_data (struct value_data *); 108 #endif 109 110 /* Free all queued updates for DEBUG_INSNs that change some reg to 111 register REGNO. */ 112 113 static void 114 free_debug_insn_changes (struct value_data *vd, unsigned int regno) 115 { 116 struct queued_debug_insn_change *cur, *next; 117 for (cur = vd->e[regno].debug_insn_changes; cur; cur = next) 118 { 119 next = cur->next; 120 --vd->n_debug_insn_changes; 121 pool_free (debug_insn_changes_pool, cur); 122 } 123 vd->e[regno].debug_insn_changes = NULL; 124 } 125 126 /* Kill register REGNO. This involves removing it from any value 127 lists, and resetting the value mode to VOIDmode. This is only a 128 helper function; it does not handle any hard registers overlapping 129 with REGNO. */ 130 131 static void 132 kill_value_one_regno (unsigned int regno, struct value_data *vd) 133 { 134 unsigned int i, next; 135 136 if (vd->e[regno].oldest_regno != regno) 137 { 138 for (i = vd->e[regno].oldest_regno; 139 vd->e[i].next_regno != regno; 140 i = vd->e[i].next_regno) 141 continue; 142 vd->e[i].next_regno = vd->e[regno].next_regno; 143 } 144 else if ((next = vd->e[regno].next_regno) != INVALID_REGNUM) 145 { 146 for (i = next; i != INVALID_REGNUM; i = vd->e[i].next_regno) 147 vd->e[i].oldest_regno = next; 148 } 149 150 vd->e[regno].mode = VOIDmode; 151 vd->e[regno].oldest_regno = regno; 152 vd->e[regno].next_regno = INVALID_REGNUM; 153 if (vd->e[regno].debug_insn_changes) 154 free_debug_insn_changes (vd, regno); 155 156 #ifdef ENABLE_CHECKING 157 validate_value_data (vd); 158 #endif 159 } 160 161 /* Kill the value in register REGNO for NREGS, and any other registers 162 whose values overlap. */ 163 164 static void 165 kill_value_regno (unsigned int regno, unsigned int nregs, 166 struct value_data *vd) 167 { 168 unsigned int j; 169 170 /* Kill the value we're told to kill. */ 171 for (j = 0; j < nregs; ++j) 172 kill_value_one_regno (regno + j, vd); 173 174 /* Kill everything that overlapped what we're told to kill. */ 175 if (regno < vd->max_value_regs) 176 j = 0; 177 else 178 j = regno - vd->max_value_regs; 179 for (; j < regno; ++j) 180 { 181 unsigned int i, n; 182 if (vd->e[j].mode == VOIDmode) 183 continue; 184 n = hard_regno_nregs[j][vd->e[j].mode]; 185 if (j + n > regno) 186 for (i = 0; i < n; ++i) 187 kill_value_one_regno (j + i, vd); 188 } 189 } 190 191 /* Kill X. This is a convenience function wrapping kill_value_regno 192 so that we mind the mode the register is in. */ 193 194 static void 195 kill_value (rtx x, struct value_data *vd) 196 { 197 rtx orig_rtx = x; 198 199 if (GET_CODE (x) == SUBREG) 200 { 201 x = simplify_subreg (GET_MODE (x), SUBREG_REG (x), 202 GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x)); 203 if (x == NULL_RTX) 204 x = SUBREG_REG (orig_rtx); 205 } 206 if (REG_P (x)) 207 { 208 unsigned int regno = REGNO (x); 209 unsigned int n = hard_regno_nregs[regno][GET_MODE (x)]; 210 211 kill_value_regno (regno, n, vd); 212 } 213 } 214 215 /* Remember that REGNO is valid in MODE. */ 216 217 static void 218 set_value_regno (unsigned int regno, enum machine_mode mode, 219 struct value_data *vd) 220 { 221 unsigned int nregs; 222 223 vd->e[regno].mode = mode; 224 225 nregs = hard_regno_nregs[regno][mode]; 226 if (nregs > vd->max_value_regs) 227 vd->max_value_regs = nregs; 228 } 229 230 /* Initialize VD such that there are no known relationships between regs. */ 231 232 static void 233 init_value_data (struct value_data *vd) 234 { 235 int i; 236 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) 237 { 238 vd->e[i].mode = VOIDmode; 239 vd->e[i].oldest_regno = i; 240 vd->e[i].next_regno = INVALID_REGNUM; 241 vd->e[i].debug_insn_changes = NULL; 242 } 243 vd->max_value_regs = 0; 244 vd->n_debug_insn_changes = 0; 245 } 246 247 /* Called through note_stores. If X is clobbered, kill its value. */ 248 249 static void 250 kill_clobbered_value (rtx x, const_rtx set, void *data) 251 { 252 struct value_data *const vd = (struct value_data *) data; 253 if (GET_CODE (set) == CLOBBER) 254 kill_value (x, vd); 255 } 256 257 /* Called through note_stores. If X is set, not clobbered, kill its 258 current value and install it as the root of its own value list. */ 259 260 static void 261 kill_set_value (rtx x, const_rtx set, void *data) 262 { 263 struct value_data *const vd = (struct value_data *) data; 264 if (GET_CODE (set) != CLOBBER) 265 { 266 kill_value (x, vd); 267 if (REG_P (x)) 268 set_value_regno (REGNO (x), GET_MODE (x), vd); 269 } 270 } 271 272 /* Called through for_each_rtx. Kill any register used as the base of an 273 auto-increment expression, and install that register as the root of its 274 own value list. */ 275 276 static int 277 kill_autoinc_value (rtx *px, void *data) 278 { 279 rtx x = *px; 280 struct value_data *const vd = (struct value_data *) data; 281 282 if (GET_RTX_CLASS (GET_CODE (x)) == RTX_AUTOINC) 283 { 284 x = XEXP (x, 0); 285 kill_value (x, vd); 286 set_value_regno (REGNO (x), GET_MODE (x), vd); 287 return -1; 288 } 289 290 return 0; 291 } 292 293 /* Assert that SRC has been copied to DEST. Adjust the data structures 294 to reflect that SRC contains an older copy of the shared value. */ 295 296 static void 297 copy_value (rtx dest, rtx src, struct value_data *vd) 298 { 299 unsigned int dr = REGNO (dest); 300 unsigned int sr = REGNO (src); 301 unsigned int dn, sn; 302 unsigned int i; 303 304 /* ??? At present, it's possible to see noop sets. It'd be nice if 305 this were cleaned up beforehand... */ 306 if (sr == dr) 307 return; 308 309 /* Do not propagate copies to the stack pointer, as that can leave 310 memory accesses with no scheduling dependency on the stack update. */ 311 if (dr == STACK_POINTER_REGNUM) 312 return; 313 314 /* Likewise with the frame pointer, if we're using one. */ 315 if (frame_pointer_needed && dr == HARD_FRAME_POINTER_REGNUM) 316 return; 317 318 /* Do not propagate copies to fixed or global registers, patterns 319 can be relying to see particular fixed register or users can 320 expect the chosen global register in asm. */ 321 if (fixed_regs[dr] || global_regs[dr]) 322 return; 323 324 /* If SRC and DEST overlap, don't record anything. */ 325 dn = hard_regno_nregs[dr][GET_MODE (dest)]; 326 sn = hard_regno_nregs[sr][GET_MODE (dest)]; 327 if ((dr > sr && dr < sr + sn) 328 || (sr > dr && sr < dr + dn)) 329 return; 330 331 /* If SRC had no assigned mode (i.e. we didn't know it was live) 332 assign it now and assume the value came from an input argument 333 or somesuch. */ 334 if (vd->e[sr].mode == VOIDmode) 335 set_value_regno (sr, vd->e[dr].mode, vd); 336 337 /* If we are narrowing the input to a smaller number of hard regs, 338 and it is in big endian, we are really extracting a high part. 339 Since we generally associate a low part of a value with the value itself, 340 we must not do the same for the high part. 341 Note we can still get low parts for the same mode combination through 342 a two-step copy involving differently sized hard regs. 343 Assume hard regs fr* are 32 bits bits each, while r* are 64 bits each: 344 (set (reg:DI r0) (reg:DI fr0)) 345 (set (reg:SI fr2) (reg:SI r0)) 346 loads the low part of (reg:DI fr0) - i.e. fr1 - into fr2, while: 347 (set (reg:SI fr2) (reg:SI fr0)) 348 loads the high part of (reg:DI fr0) into fr2. 349 350 We can't properly represent the latter case in our tables, so don't 351 record anything then. */ 352 else if (sn < (unsigned int) hard_regno_nregs[sr][vd->e[sr].mode] 353 && (GET_MODE_SIZE (vd->e[sr].mode) > UNITS_PER_WORD 354 ? WORDS_BIG_ENDIAN : BYTES_BIG_ENDIAN)) 355 return; 356 357 /* If SRC had been assigned a mode narrower than the copy, we can't 358 link DEST into the chain, because not all of the pieces of the 359 copy came from oldest_regno. */ 360 else if (sn > (unsigned int) hard_regno_nregs[sr][vd->e[sr].mode]) 361 return; 362 363 /* Link DR at the end of the value chain used by SR. */ 364 365 vd->e[dr].oldest_regno = vd->e[sr].oldest_regno; 366 367 for (i = sr; vd->e[i].next_regno != INVALID_REGNUM; i = vd->e[i].next_regno) 368 continue; 369 vd->e[i].next_regno = dr; 370 371 #ifdef ENABLE_CHECKING 372 validate_value_data (vd); 373 #endif 374 } 375 376 /* Return true if a mode change from ORIG to NEW is allowed for REGNO. */ 377 378 static bool 379 mode_change_ok (enum machine_mode orig_mode, enum machine_mode new_mode, 380 unsigned int regno ATTRIBUTE_UNUSED) 381 { 382 if (GET_MODE_SIZE (orig_mode) < GET_MODE_SIZE (new_mode)) 383 return false; 384 385 #ifdef CANNOT_CHANGE_MODE_CLASS 386 return !REG_CANNOT_CHANGE_MODE_P (regno, orig_mode, new_mode); 387 #endif 388 389 return true; 390 } 391 392 /* Register REGNO was originally set in ORIG_MODE. It - or a copy of it - 393 was copied in COPY_MODE to COPY_REGNO, and then COPY_REGNO was accessed 394 in NEW_MODE. 395 Return a NEW_MODE rtx for REGNO if that's OK, otherwise return NULL_RTX. */ 396 397 static rtx 398 maybe_mode_change (enum machine_mode orig_mode, enum machine_mode copy_mode, 399 enum machine_mode new_mode, unsigned int regno, 400 unsigned int copy_regno ATTRIBUTE_UNUSED) 401 { 402 if (GET_MODE_SIZE (copy_mode) < GET_MODE_SIZE (orig_mode) 403 && GET_MODE_SIZE (copy_mode) < GET_MODE_SIZE (new_mode)) 404 return NULL_RTX; 405 406 if (orig_mode == new_mode) 407 return gen_rtx_raw_REG (new_mode, regno); 408 else if (mode_change_ok (orig_mode, new_mode, regno)) 409 { 410 int copy_nregs = hard_regno_nregs[copy_regno][copy_mode]; 411 int use_nregs = hard_regno_nregs[copy_regno][new_mode]; 412 int copy_offset 413 = GET_MODE_SIZE (copy_mode) / copy_nregs * (copy_nregs - use_nregs); 414 int offset 415 = GET_MODE_SIZE (orig_mode) - GET_MODE_SIZE (new_mode) - copy_offset; 416 int byteoffset = offset % UNITS_PER_WORD; 417 int wordoffset = offset - byteoffset; 418 419 offset = ((WORDS_BIG_ENDIAN ? wordoffset : 0) 420 + (BYTES_BIG_ENDIAN ? byteoffset : 0)); 421 regno += subreg_regno_offset (regno, orig_mode, offset, new_mode); 422 if (HARD_REGNO_MODE_OK (regno, new_mode)) 423 return gen_rtx_raw_REG (new_mode, regno); 424 } 425 return NULL_RTX; 426 } 427 428 /* Find the oldest copy of the value contained in REGNO that is in 429 register class CL and has mode MODE. If found, return an rtx 430 of that oldest register, otherwise return NULL. */ 431 432 static rtx 433 find_oldest_value_reg (enum reg_class cl, rtx reg, struct value_data *vd) 434 { 435 unsigned int regno = REGNO (reg); 436 enum machine_mode mode = GET_MODE (reg); 437 unsigned int i; 438 439 /* If we are accessing REG in some mode other that what we set it in, 440 make sure that the replacement is valid. In particular, consider 441 (set (reg:DI r11) (...)) 442 (set (reg:SI r9) (reg:SI r11)) 443 (set (reg:SI r10) (...)) 444 (set (...) (reg:DI r9)) 445 Replacing r9 with r11 is invalid. */ 446 if (mode != vd->e[regno].mode) 447 { 448 if (hard_regno_nregs[regno][mode] 449 > hard_regno_nregs[regno][vd->e[regno].mode]) 450 return NULL_RTX; 451 } 452 453 for (i = vd->e[regno].oldest_regno; i != regno; i = vd->e[i].next_regno) 454 { 455 enum machine_mode oldmode = vd->e[i].mode; 456 rtx new_rtx; 457 458 if (!in_hard_reg_set_p (reg_class_contents[cl], mode, i)) 459 continue; 460 461 new_rtx = maybe_mode_change (oldmode, vd->e[regno].mode, mode, i, regno); 462 if (new_rtx) 463 { 464 ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (reg); 465 REG_ATTRS (new_rtx) = REG_ATTRS (reg); 466 REG_POINTER (new_rtx) = REG_POINTER (reg); 467 return new_rtx; 468 } 469 } 470 471 return NULL_RTX; 472 } 473 474 /* If possible, replace the register at *LOC with the oldest register 475 in register class CL. Return true if successfully replaced. */ 476 477 static bool 478 replace_oldest_value_reg (rtx *loc, enum reg_class cl, rtx insn, 479 struct value_data *vd) 480 { 481 rtx new_rtx = find_oldest_value_reg (cl, *loc, vd); 482 if (new_rtx) 483 { 484 if (DEBUG_INSN_P (insn)) 485 { 486 struct queued_debug_insn_change *change; 487 488 if (dump_file) 489 fprintf (dump_file, "debug_insn %u: queued replacing reg %u with %u\n", 490 INSN_UID (insn), REGNO (*loc), REGNO (new_rtx)); 491 492 change = (struct queued_debug_insn_change *) 493 pool_alloc (debug_insn_changes_pool); 494 change->next = vd->e[REGNO (new_rtx)].debug_insn_changes; 495 change->insn = insn; 496 change->loc = loc; 497 change->new_rtx = new_rtx; 498 vd->e[REGNO (new_rtx)].debug_insn_changes = change; 499 ++vd->n_debug_insn_changes; 500 return true; 501 } 502 if (dump_file) 503 fprintf (dump_file, "insn %u: replaced reg %u with %u\n", 504 INSN_UID (insn), REGNO (*loc), REGNO (new_rtx)); 505 506 validate_change (insn, loc, new_rtx, 1); 507 return true; 508 } 509 return false; 510 } 511 512 /* Similar to replace_oldest_value_reg, but *LOC contains an address. 513 Adapted from find_reloads_address_1. CL is INDEX_REG_CLASS or 514 BASE_REG_CLASS depending on how the register is being considered. */ 515 516 static bool 517 replace_oldest_value_addr (rtx *loc, enum reg_class cl, 518 enum machine_mode mode, addr_space_t as, 519 rtx insn, struct value_data *vd) 520 { 521 rtx x = *loc; 522 RTX_CODE code = GET_CODE (x); 523 const char *fmt; 524 int i, j; 525 bool changed = false; 526 527 switch (code) 528 { 529 case PLUS: 530 if (DEBUG_INSN_P (insn)) 531 break; 532 533 { 534 rtx orig_op0 = XEXP (x, 0); 535 rtx orig_op1 = XEXP (x, 1); 536 RTX_CODE code0 = GET_CODE (orig_op0); 537 RTX_CODE code1 = GET_CODE (orig_op1); 538 rtx op0 = orig_op0; 539 rtx op1 = orig_op1; 540 rtx *locI = NULL; 541 rtx *locB = NULL; 542 enum rtx_code index_code = SCRATCH; 543 544 if (GET_CODE (op0) == SUBREG) 545 { 546 op0 = SUBREG_REG (op0); 547 code0 = GET_CODE (op0); 548 } 549 550 if (GET_CODE (op1) == SUBREG) 551 { 552 op1 = SUBREG_REG (op1); 553 code1 = GET_CODE (op1); 554 } 555 556 if (code0 == MULT || code0 == SIGN_EXTEND || code0 == TRUNCATE 557 || code0 == ZERO_EXTEND || code1 == MEM) 558 { 559 locI = &XEXP (x, 0); 560 locB = &XEXP (x, 1); 561 index_code = GET_CODE (*locI); 562 } 563 else if (code1 == MULT || code1 == SIGN_EXTEND || code1 == TRUNCATE 564 || code1 == ZERO_EXTEND || code0 == MEM) 565 { 566 locI = &XEXP (x, 1); 567 locB = &XEXP (x, 0); 568 index_code = GET_CODE (*locI); 569 } 570 else if (code0 == CONST_INT || code0 == CONST 571 || code0 == SYMBOL_REF || code0 == LABEL_REF) 572 { 573 locB = &XEXP (x, 1); 574 index_code = GET_CODE (XEXP (x, 0)); 575 } 576 else if (code1 == CONST_INT || code1 == CONST 577 || code1 == SYMBOL_REF || code1 == LABEL_REF) 578 { 579 locB = &XEXP (x, 0); 580 index_code = GET_CODE (XEXP (x, 1)); 581 } 582 else if (code0 == REG && code1 == REG) 583 { 584 int index_op; 585 unsigned regno0 = REGNO (op0), regno1 = REGNO (op1); 586 587 if (REGNO_OK_FOR_INDEX_P (regno1) 588 && regno_ok_for_base_p (regno0, mode, as, PLUS, REG)) 589 index_op = 1; 590 else if (REGNO_OK_FOR_INDEX_P (regno0) 591 && regno_ok_for_base_p (regno1, mode, as, PLUS, REG)) 592 index_op = 0; 593 else if (regno_ok_for_base_p (regno0, mode, as, PLUS, REG) 594 || REGNO_OK_FOR_INDEX_P (regno1)) 595 index_op = 1; 596 else if (regno_ok_for_base_p (regno1, mode, as, PLUS, REG)) 597 index_op = 0; 598 else 599 index_op = 1; 600 601 locI = &XEXP (x, index_op); 602 locB = &XEXP (x, !index_op); 603 index_code = GET_CODE (*locI); 604 } 605 else if (code0 == REG) 606 { 607 locI = &XEXP (x, 0); 608 locB = &XEXP (x, 1); 609 index_code = GET_CODE (*locI); 610 } 611 else if (code1 == REG) 612 { 613 locI = &XEXP (x, 1); 614 locB = &XEXP (x, 0); 615 index_code = GET_CODE (*locI); 616 } 617 618 if (locI) 619 changed |= replace_oldest_value_addr (locI, INDEX_REG_CLASS, 620 mode, as, insn, vd); 621 if (locB) 622 changed |= replace_oldest_value_addr (locB, 623 base_reg_class (mode, as, PLUS, 624 index_code), 625 mode, as, insn, vd); 626 return changed; 627 } 628 629 case POST_INC: 630 case POST_DEC: 631 case POST_MODIFY: 632 case PRE_INC: 633 case PRE_DEC: 634 case PRE_MODIFY: 635 return false; 636 637 case MEM: 638 return replace_oldest_value_mem (x, insn, vd); 639 640 case REG: 641 return replace_oldest_value_reg (loc, cl, insn, vd); 642 643 default: 644 break; 645 } 646 647 fmt = GET_RTX_FORMAT (code); 648 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) 649 { 650 if (fmt[i] == 'e') 651 changed |= replace_oldest_value_addr (&XEXP (x, i), cl, mode, as, 652 insn, vd); 653 else if (fmt[i] == 'E') 654 for (j = XVECLEN (x, i) - 1; j >= 0; j--) 655 changed |= replace_oldest_value_addr (&XVECEXP (x, i, j), cl, 656 mode, as, insn, vd); 657 } 658 659 return changed; 660 } 661 662 /* Similar to replace_oldest_value_reg, but X contains a memory. */ 663 664 static bool 665 replace_oldest_value_mem (rtx x, rtx insn, struct value_data *vd) 666 { 667 enum reg_class cl; 668 669 if (DEBUG_INSN_P (insn)) 670 cl = ALL_REGS; 671 else 672 cl = base_reg_class (GET_MODE (x), MEM_ADDR_SPACE (x), MEM, SCRATCH); 673 674 return replace_oldest_value_addr (&XEXP (x, 0), cl, 675 GET_MODE (x), MEM_ADDR_SPACE (x), 676 insn, vd); 677 } 678 679 /* Apply all queued updates for DEBUG_INSNs that change some reg to 680 register REGNO. */ 681 682 static void 683 apply_debug_insn_changes (struct value_data *vd, unsigned int regno) 684 { 685 struct queued_debug_insn_change *change; 686 rtx last_insn = vd->e[regno].debug_insn_changes->insn; 687 688 for (change = vd->e[regno].debug_insn_changes; 689 change; 690 change = change->next) 691 { 692 if (last_insn != change->insn) 693 { 694 apply_change_group (); 695 last_insn = change->insn; 696 } 697 validate_change (change->insn, change->loc, change->new_rtx, 1); 698 } 699 apply_change_group (); 700 } 701 702 /* Called via for_each_rtx, for all used registers in a real 703 insn apply DEBUG_INSN changes that change registers to the 704 used register. */ 705 706 static int 707 cprop_find_used_regs_1 (rtx *loc, void *data) 708 { 709 if (REG_P (*loc)) 710 { 711 struct value_data *vd = (struct value_data *) data; 712 if (vd->e[REGNO (*loc)].debug_insn_changes) 713 { 714 apply_debug_insn_changes (vd, REGNO (*loc)); 715 free_debug_insn_changes (vd, REGNO (*loc)); 716 } 717 } 718 return 0; 719 } 720 721 /* Called via note_uses, for all used registers in a real insn 722 apply DEBUG_INSN changes that change registers to the used 723 registers. */ 724 725 static void 726 cprop_find_used_regs (rtx *loc, void *vd) 727 { 728 for_each_rtx (loc, cprop_find_used_regs_1, vd); 729 } 730 731 /* Perform the forward copy propagation on basic block BB. */ 732 733 static bool 734 copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd) 735 { 736 bool anything_changed = false; 737 rtx insn; 738 739 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn)) 740 { 741 int n_ops, i, alt, predicated; 742 bool is_asm, any_replacements; 743 rtx set; 744 rtx link; 745 bool replaced[MAX_RECOG_OPERANDS]; 746 bool changed = false; 747 748 if (!NONDEBUG_INSN_P (insn)) 749 { 750 if (DEBUG_INSN_P (insn)) 751 { 752 rtx loc = INSN_VAR_LOCATION_LOC (insn); 753 if (!VAR_LOC_UNKNOWN_P (loc)) 754 replace_oldest_value_addr (&INSN_VAR_LOCATION_LOC (insn), 755 ALL_REGS, GET_MODE (loc), 756 ADDR_SPACE_GENERIC, insn, vd); 757 } 758 759 if (insn == BB_END (bb)) 760 break; 761 else 762 continue; 763 } 764 765 set = single_set (insn); 766 extract_insn (insn); 767 if (! constrain_operands (1)) 768 fatal_insn_not_found (insn); 769 preprocess_constraints (); 770 alt = which_alternative; 771 n_ops = recog_data.n_operands; 772 is_asm = asm_noperands (PATTERN (insn)) >= 0; 773 774 /* Simplify the code below by rewriting things to reflect 775 matching constraints. Also promote OP_OUT to OP_INOUT 776 in predicated instructions. */ 777 778 predicated = GET_CODE (PATTERN (insn)) == COND_EXEC; 779 for (i = 0; i < n_ops; ++i) 780 { 781 int matches = recog_op_alt[i][alt].matches; 782 if (matches >= 0) 783 recog_op_alt[i][alt].cl = recog_op_alt[matches][alt].cl; 784 if (matches >= 0 || recog_op_alt[i][alt].matched >= 0 785 || (predicated && recog_data.operand_type[i] == OP_OUT)) 786 recog_data.operand_type[i] = OP_INOUT; 787 } 788 789 /* Apply changes to earlier DEBUG_INSNs if possible. */ 790 if (vd->n_debug_insn_changes) 791 note_uses (&PATTERN (insn), cprop_find_used_regs, vd); 792 793 /* For each earlyclobber operand, zap the value data. */ 794 for (i = 0; i < n_ops; i++) 795 if (recog_op_alt[i][alt].earlyclobber) 796 kill_value (recog_data.operand[i], vd); 797 798 /* Within asms, a clobber cannot overlap inputs or outputs. 799 I wouldn't think this were true for regular insns, but 800 scan_rtx treats them like that... */ 801 note_stores (PATTERN (insn), kill_clobbered_value, vd); 802 803 /* Kill all auto-incremented values. */ 804 /* ??? REG_INC is useless, since stack pushes aren't done that way. */ 805 for_each_rtx (&PATTERN (insn), kill_autoinc_value, vd); 806 807 /* Kill all early-clobbered operands. */ 808 for (i = 0; i < n_ops; i++) 809 if (recog_op_alt[i][alt].earlyclobber) 810 kill_value (recog_data.operand[i], vd); 811 812 /* If we have dead sets in the insn, then we need to note these as we 813 would clobbers. */ 814 for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) 815 { 816 if (REG_NOTE_KIND (link) == REG_UNUSED) 817 { 818 kill_value (XEXP (link, 0), vd); 819 /* Furthermore, if the insn looked like a single-set, 820 but the dead store kills the source value of that 821 set, then we can no-longer use the plain move 822 special case below. */ 823 if (set 824 && reg_overlap_mentioned_p (XEXP (link, 0), SET_SRC (set))) 825 set = NULL; 826 } 827 } 828 829 /* Special-case plain move instructions, since we may well 830 be able to do the move from a different register class. */ 831 if (set && REG_P (SET_SRC (set))) 832 { 833 rtx src = SET_SRC (set); 834 unsigned int regno = REGNO (src); 835 enum machine_mode mode = GET_MODE (src); 836 unsigned int i; 837 rtx new_rtx; 838 839 /* If we are accessing SRC in some mode other that what we 840 set it in, make sure that the replacement is valid. */ 841 if (mode != vd->e[regno].mode) 842 { 843 if (hard_regno_nregs[regno][mode] 844 > hard_regno_nregs[regno][vd->e[regno].mode]) 845 goto no_move_special_case; 846 847 /* And likewise, if we are narrowing on big endian the transformation 848 is also invalid. */ 849 if (hard_regno_nregs[regno][mode] 850 < hard_regno_nregs[regno][vd->e[regno].mode] 851 && (GET_MODE_SIZE (vd->e[regno].mode) > UNITS_PER_WORD 852 ? WORDS_BIG_ENDIAN : BYTES_BIG_ENDIAN)) 853 goto no_move_special_case; 854 } 855 856 /* If the destination is also a register, try to find a source 857 register in the same class. */ 858 if (REG_P (SET_DEST (set))) 859 { 860 new_rtx = find_oldest_value_reg (REGNO_REG_CLASS (regno), src, vd); 861 if (new_rtx && validate_change (insn, &SET_SRC (set), new_rtx, 0)) 862 { 863 if (dump_file) 864 fprintf (dump_file, 865 "insn %u: replaced reg %u with %u\n", 866 INSN_UID (insn), regno, REGNO (new_rtx)); 867 changed = true; 868 goto did_replacement; 869 } 870 /* We need to re-extract as validate_change clobbers 871 recog_data. */ 872 extract_insn (insn); 873 if (! constrain_operands (1)) 874 fatal_insn_not_found (insn); 875 preprocess_constraints (); 876 } 877 878 /* Otherwise, try all valid registers and see if its valid. */ 879 for (i = vd->e[regno].oldest_regno; i != regno; 880 i = vd->e[i].next_regno) 881 { 882 new_rtx = maybe_mode_change (vd->e[i].mode, vd->e[regno].mode, 883 mode, i, regno); 884 if (new_rtx != NULL_RTX) 885 { 886 if (validate_change (insn, &SET_SRC (set), new_rtx, 0)) 887 { 888 ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (src); 889 REG_ATTRS (new_rtx) = REG_ATTRS (src); 890 REG_POINTER (new_rtx) = REG_POINTER (src); 891 if (dump_file) 892 fprintf (dump_file, 893 "insn %u: replaced reg %u with %u\n", 894 INSN_UID (insn), regno, REGNO (new_rtx)); 895 changed = true; 896 goto did_replacement; 897 } 898 /* We need to re-extract as validate_change clobbers 899 recog_data. */ 900 extract_insn (insn); 901 if (! constrain_operands (1)) 902 fatal_insn_not_found (insn); 903 preprocess_constraints (); 904 } 905 } 906 } 907 no_move_special_case: 908 909 any_replacements = false; 910 911 /* For each input operand, replace a hard register with the 912 eldest live copy that's in an appropriate register class. */ 913 for (i = 0; i < n_ops; i++) 914 { 915 replaced[i] = false; 916 917 /* Don't scan match_operand here, since we've no reg class 918 information to pass down. Any operands that we could 919 substitute in will be represented elsewhere. */ 920 if (recog_data.constraints[i][0] == '\0') 921 continue; 922 923 /* Don't replace in asms intentionally referencing hard regs. */ 924 if (is_asm && REG_P (recog_data.operand[i]) 925 && (REGNO (recog_data.operand[i]) 926 == ORIGINAL_REGNO (recog_data.operand[i]))) 927 continue; 928 929 if (recog_data.operand_type[i] == OP_IN) 930 { 931 if (recog_op_alt[i][alt].is_address) 932 replaced[i] 933 = replace_oldest_value_addr (recog_data.operand_loc[i], 934 recog_op_alt[i][alt].cl, 935 VOIDmode, ADDR_SPACE_GENERIC, 936 insn, vd); 937 else if (REG_P (recog_data.operand[i])) 938 replaced[i] 939 = replace_oldest_value_reg (recog_data.operand_loc[i], 940 recog_op_alt[i][alt].cl, 941 insn, vd); 942 else if (MEM_P (recog_data.operand[i])) 943 replaced[i] = replace_oldest_value_mem (recog_data.operand[i], 944 insn, vd); 945 } 946 else if (MEM_P (recog_data.operand[i])) 947 replaced[i] = replace_oldest_value_mem (recog_data.operand[i], 948 insn, vd); 949 950 /* If we performed any replacement, update match_dups. */ 951 if (replaced[i]) 952 { 953 int j; 954 rtx new_rtx; 955 956 new_rtx = *recog_data.operand_loc[i]; 957 recog_data.operand[i] = new_rtx; 958 for (j = 0; j < recog_data.n_dups; j++) 959 if (recog_data.dup_num[j] == i) 960 validate_unshare_change (insn, recog_data.dup_loc[j], new_rtx, 1); 961 962 any_replacements = true; 963 } 964 } 965 966 if (any_replacements) 967 { 968 if (! apply_change_group ()) 969 { 970 for (i = 0; i < n_ops; i++) 971 if (replaced[i]) 972 { 973 rtx old = *recog_data.operand_loc[i]; 974 recog_data.operand[i] = old; 975 } 976 977 if (dump_file) 978 fprintf (dump_file, 979 "insn %u: reg replacements not verified\n", 980 INSN_UID (insn)); 981 } 982 else 983 changed = true; 984 } 985 986 did_replacement: 987 if (changed) 988 { 989 anything_changed = true; 990 991 /* If something changed, perhaps further changes to earlier 992 DEBUG_INSNs can be applied. */ 993 if (vd->n_debug_insn_changes) 994 note_uses (&PATTERN (insn), cprop_find_used_regs, vd); 995 } 996 997 /* Clobber call-clobbered registers. */ 998 if (CALL_P (insn)) 999 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) 1000 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)) 1001 kill_value_regno (i, 1, vd); 1002 1003 /* Notice stores. */ 1004 note_stores (PATTERN (insn), kill_set_value, vd); 1005 1006 /* Notice copies. */ 1007 if (set && REG_P (SET_DEST (set)) && REG_P (SET_SRC (set))) 1008 copy_value (SET_DEST (set), SET_SRC (set), vd); 1009 1010 if (insn == BB_END (bb)) 1011 break; 1012 } 1013 1014 return anything_changed; 1015 } 1016 1017 /* Main entry point for the forward copy propagation optimization. */ 1018 1019 static unsigned int 1020 copyprop_hardreg_forward (void) 1021 { 1022 struct value_data *all_vd; 1023 basic_block bb; 1024 sbitmap visited; 1025 bool analyze_called = false; 1026 1027 all_vd = XNEWVEC (struct value_data, last_basic_block); 1028 1029 visited = sbitmap_alloc (last_basic_block); 1030 sbitmap_zero (visited); 1031 1032 if (MAY_HAVE_DEBUG_INSNS) 1033 debug_insn_changes_pool 1034 = create_alloc_pool ("debug insn changes pool", 1035 sizeof (struct queued_debug_insn_change), 256); 1036 1037 FOR_EACH_BB (bb) 1038 { 1039 SET_BIT (visited, bb->index); 1040 1041 /* If a block has a single predecessor, that we've already 1042 processed, begin with the value data that was live at 1043 the end of the predecessor block. */ 1044 /* ??? Ought to use more intelligent queuing of blocks. */ 1045 if (single_pred_p (bb) 1046 && TEST_BIT (visited, single_pred (bb)->index) 1047 && ! (single_pred_edge (bb)->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))) 1048 { 1049 all_vd[bb->index] = all_vd[single_pred (bb)->index]; 1050 if (all_vd[bb->index].n_debug_insn_changes) 1051 { 1052 unsigned int regno; 1053 1054 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) 1055 { 1056 if (all_vd[bb->index].e[regno].debug_insn_changes) 1057 { 1058 all_vd[bb->index].e[regno].debug_insn_changes = NULL; 1059 if (--all_vd[bb->index].n_debug_insn_changes == 0) 1060 break; 1061 } 1062 } 1063 } 1064 } 1065 else 1066 init_value_data (all_vd + bb->index); 1067 1068 copyprop_hardreg_forward_1 (bb, all_vd + bb->index); 1069 } 1070 1071 if (MAY_HAVE_DEBUG_INSNS) 1072 { 1073 FOR_EACH_BB (bb) 1074 if (TEST_BIT (visited, bb->index) 1075 && all_vd[bb->index].n_debug_insn_changes) 1076 { 1077 unsigned int regno; 1078 bitmap live; 1079 1080 if (!analyze_called) 1081 { 1082 df_analyze (); 1083 analyze_called = true; 1084 } 1085 live = df_get_live_out (bb); 1086 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) 1087 if (all_vd[bb->index].e[regno].debug_insn_changes) 1088 { 1089 if (REGNO_REG_SET_P (live, regno)) 1090 apply_debug_insn_changes (all_vd + bb->index, regno); 1091 if (all_vd[bb->index].n_debug_insn_changes == 0) 1092 break; 1093 } 1094 } 1095 1096 free_alloc_pool (debug_insn_changes_pool); 1097 } 1098 1099 sbitmap_free (visited); 1100 free (all_vd); 1101 return 0; 1102 } 1103 1104 /* Dump the value chain data to stderr. */ 1105 1106 DEBUG_FUNCTION void 1107 debug_value_data (struct value_data *vd) 1108 { 1109 HARD_REG_SET set; 1110 unsigned int i, j; 1111 1112 CLEAR_HARD_REG_SET (set); 1113 1114 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) 1115 if (vd->e[i].oldest_regno == i) 1116 { 1117 if (vd->e[i].mode == VOIDmode) 1118 { 1119 if (vd->e[i].next_regno != INVALID_REGNUM) 1120 fprintf (stderr, "[%u] Bad next_regno for empty chain (%u)\n", 1121 i, vd->e[i].next_regno); 1122 continue; 1123 } 1124 1125 SET_HARD_REG_BIT (set, i); 1126 fprintf (stderr, "[%u %s] ", i, GET_MODE_NAME (vd->e[i].mode)); 1127 1128 for (j = vd->e[i].next_regno; 1129 j != INVALID_REGNUM; 1130 j = vd->e[j].next_regno) 1131 { 1132 if (TEST_HARD_REG_BIT (set, j)) 1133 { 1134 fprintf (stderr, "[%u] Loop in regno chain\n", j); 1135 return; 1136 } 1137 1138 if (vd->e[j].oldest_regno != i) 1139 { 1140 fprintf (stderr, "[%u] Bad oldest_regno (%u)\n", 1141 j, vd->e[j].oldest_regno); 1142 return; 1143 } 1144 SET_HARD_REG_BIT (set, j); 1145 fprintf (stderr, "[%u %s] ", j, GET_MODE_NAME (vd->e[j].mode)); 1146 } 1147 fputc ('\n', stderr); 1148 } 1149 1150 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) 1151 if (! TEST_HARD_REG_BIT (set, i) 1152 && (vd->e[i].mode != VOIDmode 1153 || vd->e[i].oldest_regno != i 1154 || vd->e[i].next_regno != INVALID_REGNUM)) 1155 fprintf (stderr, "[%u] Non-empty reg in chain (%s %u %i)\n", 1156 i, GET_MODE_NAME (vd->e[i].mode), vd->e[i].oldest_regno, 1157 vd->e[i].next_regno); 1158 } 1159 1160 #ifdef ENABLE_CHECKING 1161 static void 1162 validate_value_data (struct value_data *vd) 1163 { 1164 HARD_REG_SET set; 1165 unsigned int i, j; 1166 1167 CLEAR_HARD_REG_SET (set); 1168 1169 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) 1170 if (vd->e[i].oldest_regno == i) 1171 { 1172 if (vd->e[i].mode == VOIDmode) 1173 { 1174 if (vd->e[i].next_regno != INVALID_REGNUM) 1175 internal_error ("validate_value_data: [%u] Bad next_regno for empty chain (%u)", 1176 i, vd->e[i].next_regno); 1177 continue; 1178 } 1179 1180 SET_HARD_REG_BIT (set, i); 1181 1182 for (j = vd->e[i].next_regno; 1183 j != INVALID_REGNUM; 1184 j = vd->e[j].next_regno) 1185 { 1186 if (TEST_HARD_REG_BIT (set, j)) 1187 internal_error ("validate_value_data: Loop in regno chain (%u)", 1188 j); 1189 if (vd->e[j].oldest_regno != i) 1190 internal_error ("validate_value_data: [%u] Bad oldest_regno (%u)", 1191 j, vd->e[j].oldest_regno); 1192 1193 SET_HARD_REG_BIT (set, j); 1194 } 1195 } 1196 1197 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) 1198 if (! TEST_HARD_REG_BIT (set, i) 1199 && (vd->e[i].mode != VOIDmode 1200 || vd->e[i].oldest_regno != i 1201 || vd->e[i].next_regno != INVALID_REGNUM)) 1202 internal_error ("validate_value_data: [%u] Non-empty reg in chain (%s %u %i)", 1203 i, GET_MODE_NAME (vd->e[i].mode), vd->e[i].oldest_regno, 1204 vd->e[i].next_regno); 1205 } 1206 #endif 1207 1208 static bool 1209 gate_handle_cprop (void) 1210 { 1211 return (optimize > 0 && (flag_cprop_registers)); 1212 } 1213 1214 1215 struct rtl_opt_pass pass_cprop_hardreg = 1216 { 1217 { 1218 RTL_PASS, 1219 "cprop_hardreg", /* name */ 1220 gate_handle_cprop, /* gate */ 1221 copyprop_hardreg_forward, /* execute */ 1222 NULL, /* sub */ 1223 NULL, /* next */ 1224 0, /* static_pass_number */ 1225 TV_CPROP_REGISTERS, /* tv_id */ 1226 0, /* properties_required */ 1227 0, /* properties_provided */ 1228 0, /* properties_destroyed */ 1229 0, /* todo_flags_start */ 1230 TODO_df_finish 1231 | TODO_verify_rtl_sharing /* todo_flags_finish */ 1232 } 1233 }; 1234