| 1 | /* Optimize jump instructions, for GNU compiler. |
| 2 | Copyright (C) 1987, 1988, 1989 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GNU CC. |
| 5 | |
| 6 | GNU CC is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 1, or (at your option) |
| 9 | any later version. |
| 10 | |
| 11 | GNU CC is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with GNU CC; see the file COPYING. If not, write to |
| 18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ |
| 19 | |
| 20 | |
| 21 | /* This is the jump-optimization pass of the compiler. |
| 22 | It is run two or three times: once before cse, sometimes once after cse, |
| 23 | and once after reload (before final). |
| 24 | |
| 25 | jump_optimize deletes unreachable code and labels that are not used. |
| 26 | It also deletes jumps that jump to the following insn, |
| 27 | and simplifies jumps around unconditional jumps and jumps |
| 28 | to unconditional jumps. |
| 29 | |
| 30 | Each CODE_LABEL has a count of the times it is used |
| 31 | stored in the LABEL_NUSES internal field, and each JUMP_INSN |
| 32 | has one label that it refers to stored in the |
| 33 | JUMP_LABEL internal field. With this we can detect labels that |
| 34 | become unused because of the deletion of all the jumps that |
| 35 | formerly used them. The JUMP_LABEL info is sometimes looked |
| 36 | at by later passes. |
| 37 | |
| 38 | Optionally, cross-jumping can be done. Currently it is done |
| 39 | only the last time (when after reload and before final). |
| 40 | In fact, the code for cross-jumping now assumes that register |
| 41 | allocation has been done, since it uses `rtx_renumbered_equal_p'. |
| 42 | |
| 43 | Jump optimization is done after cse when cse's constant-propagation |
| 44 | causes jumps to become unconditional or to be deleted. |
| 45 | |
| 46 | Unreachable loops are not detected here, because the labels |
| 47 | have references and the insns appear reachable from the labels. |
| 48 | find_basic_blocks in flow.c finds and deletes such loops. |
| 49 | |
| 50 | The subroutines delete_insn, redirect_jump, invert_jump, next_real_insn |
| 51 | and prev_real_insn are used from other passes as well. */ |
| 52 | |
| 53 | #include "config.h" |
| 54 | #include "rtl.h" |
| 55 | #include "flags.h" |
| 56 | #include "regs.h" |
| 57 | |
| 58 | /* ??? Eventually must record somehow the labels used by jumps |
| 59 | from nested functions. */ |
| 60 | /* Pre-record the next or previous real insn for each label? |
| 61 | No, this pass is very fast anyway. */ |
| 62 | /* Condense consecutive labels? |
| 63 | This would make life analysis faster, maybe. */ |
| 64 | /* Optimize jump y; x: ... y: jumpif... x? |
| 65 | Don't know if it is worth bothering with. */ |
| 66 | /* Optimize two cases of conditional jump to conditional jump? |
| 67 | This can never delete any instruction or make anything dead, |
| 68 | or even change what is live at any point. |
| 69 | So perhaps let combiner do it. */ |
| 70 | |
| 71 | /* Vector indexed by uid. |
| 72 | For each CODE_LABEL, index by its uid to get first unconditional jump |
| 73 | that jumps to the label. |
| 74 | For each JUMP_INSN, index by its uid to get the next unconditional jump |
| 75 | that jumps to the same label. |
| 76 | Element 0 is the start of a chain of all return insns. |
| 77 | (It is safe to use element 0 because insn uid 0 is not used. */ |
| 78 | |
| 79 | rtx *jump_chain; |
| 80 | |
| 81 | rtx delete_insn (); |
| 82 | void redirect_jump (); |
| 83 | void invert_jump (); |
| 84 | rtx next_real_insn (); |
| 85 | rtx prev_real_insn (); |
| 86 | rtx next_label (); |
| 87 | |
| 88 | static void mark_jump_label (); |
| 89 | static void delete_jump (); |
| 90 | static void squeeze_block_notes (); |
| 91 | void invert_exp (); |
| 92 | static void redirect_exp (); |
| 93 | static rtx follow_jumps (); |
| 94 | static int tension_vector_labels (); |
| 95 | static void find_cross_jump (); |
| 96 | static void do_cross_jump (); |
| 97 | static enum rtx_code reverse_condition (); |
| 98 | static int jump_back_p (); |
| 99 | int condjump_p (); |
| 100 | \f |
| 101 | /* Delete no-op jumps and optimize jumps to jumps |
| 102 | and jumps around jumps. |
| 103 | Delete unused labels and unreachable code. |
| 104 | If CROSS_JUMP is nonzero, detect matching code |
| 105 | before a jump and its destination and unify them. |
| 106 | If NOOP_MOVES is nonzero, also delete no-op move insns. |
| 107 | |
| 108 | If `optimize' is zero, don't change any code, |
| 109 | just determine whether control drops off the end of the function. |
| 110 | This case occurs when we have -W and not -O. |
| 111 | It works because `delete_insn' checks the value of `optimize' |
| 112 | and refrains from actually deleting when that is 0. */ |
| 113 | |
| 114 | void |
| 115 | jump_optimize (f, cross_jump, noop_moves) |
| 116 | rtx f; |
| 117 | { |
| 118 | register rtx insn; |
| 119 | int changed; |
| 120 | int first = 1; |
| 121 | int max_uid = 0; |
| 122 | rtx last_insn; |
| 123 | |
| 124 | /* Initialize LABEL_NUSES and JUMP_LABEL fields. */ |
| 125 | |
| 126 | for (insn = f; insn; insn = NEXT_INSN (insn)) |
| 127 | { |
| 128 | if (GET_CODE (insn) == CODE_LABEL) |
| 129 | LABEL_NUSES (insn) = 0; |
| 130 | if (GET_CODE (insn) == JUMP_INSN) |
| 131 | JUMP_LABEL (insn) = 0; |
| 132 | if (INSN_UID (insn) > max_uid) |
| 133 | max_uid = INSN_UID (insn); |
| 134 | } |
| 135 | |
| 136 | max_uid++; |
| 137 | |
| 138 | jump_chain = (rtx *) alloca (max_uid * sizeof (rtx)); |
| 139 | bzero (jump_chain, max_uid * sizeof (rtx)); |
| 140 | |
| 141 | /* Delete insns following barriers, up to next label. */ |
| 142 | |
| 143 | for (insn = f; insn;) |
| 144 | { |
| 145 | if (GET_CODE (insn) == BARRIER) |
| 146 | { |
| 147 | insn = NEXT_INSN (insn); |
| 148 | while (insn != 0 && GET_CODE (insn) != CODE_LABEL) |
| 149 | { |
| 150 | if (GET_CODE (insn) == NOTE |
| 151 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END) |
| 152 | insn = NEXT_INSN (insn); |
| 153 | else |
| 154 | insn = delete_insn (insn); |
| 155 | } |
| 156 | /* INSN is now the code_label. */ |
| 157 | } |
| 158 | else |
| 159 | insn = NEXT_INSN (insn); |
| 160 | } |
| 161 | |
| 162 | /* Mark the label each jump jumps to. |
| 163 | Combine consecutive labels, and count uses of labels. |
| 164 | |
| 165 | For each label, make a chain (using `jump_chain') |
| 166 | of all the *unconditional* jumps that jump to it; |
| 167 | also make a chain of all returns. */ |
| 168 | |
| 169 | for (insn = f; insn; insn = NEXT_INSN (insn)) |
| 170 | if (GET_CODE (insn) == JUMP_INSN && ! INSN_DELETED_P (insn)) |
| 171 | { |
| 172 | mark_jump_label (PATTERN (insn), insn, cross_jump); |
| 173 | if (JUMP_LABEL (insn) != 0 && simplejump_p (insn)) |
| 174 | { |
| 175 | jump_chain[INSN_UID (insn)] |
| 176 | = jump_chain[INSN_UID (JUMP_LABEL (insn))]; |
| 177 | jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn; |
| 178 | } |
| 179 | if (GET_CODE (PATTERN (insn)) == RETURN) |
| 180 | { |
| 181 | jump_chain[INSN_UID (insn)] = jump_chain[0]; |
| 182 | jump_chain[0] = insn; |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | /* Delete all labels already not referenced. |
| 187 | Also find the last insn. */ |
| 188 | |
| 189 | last_insn = 0; |
| 190 | for (insn = f; insn; ) |
| 191 | { |
| 192 | if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0) |
| 193 | insn = delete_insn (insn); |
| 194 | else |
| 195 | { |
| 196 | last_insn = insn; |
| 197 | insn = NEXT_INSN (insn); |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | if (!optimize) |
| 202 | { |
| 203 | /* See if there is still a NOTE_INSN_FUNCTION_END in this function. |
| 204 | If so record that this function can drop off the end. */ |
| 205 | |
| 206 | insn = last_insn; |
| 207 | { |
| 208 | int n_labels = 1; |
| 209 | while (insn |
| 210 | /* One label can follow the end-note: the return label. */ |
| 211 | && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0) |
| 212 | /* Ordinary insns can follow it if returning a structure. */ |
| 213 | || GET_CODE (insn) == INSN |
| 214 | /* If machine uses explicit RETURN insns, no epilogue, |
| 215 | then one of them follows the note. */ |
| 216 | || (GET_CODE (insn) == JUMP_INSN |
| 217 | && GET_CODE (PATTERN (insn)) == RETURN) |
| 218 | /* Other kinds of notes can follow also. */ |
| 219 | || (GET_CODE (insn) == NOTE |
| 220 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END))) |
| 221 | insn = PREV_INSN (insn); |
| 222 | } |
| 223 | |
| 224 | if (insn && GET_CODE (insn) == NOTE |
| 225 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END |
| 226 | && ! INSN_DELETED_P (insn)) |
| 227 | { |
| 228 | extern int current_function_returns_null; |
| 229 | current_function_returns_null = 1; |
| 230 | } |
| 231 | /* Zero the "deleted" flag of all the "deleted" insns. */ |
| 232 | for (insn = f; insn; insn = NEXT_INSN (insn)) |
| 233 | INSN_DELETED_P (insn) = 0; |
| 234 | return; |
| 235 | } |
| 236 | |
| 237 | if (noop_moves) |
| 238 | for (insn = f; insn; ) |
| 239 | { |
| 240 | register rtx next = NEXT_INSN (insn); |
| 241 | |
| 242 | if (GET_CODE (insn) == INSN) |
| 243 | { |
| 244 | register rtx body = PATTERN (insn); |
| 245 | |
| 246 | #if 0 /* Keep these insns, since they are used for conditional branch |
| 247 | scheduling peepholes on the sparc. */ |
| 248 | #endif |
| 249 | /* Delete insns that existed just to advise flow-analysis. */ |
| 250 | |
| 251 | if (GET_CODE (body) == USE |
| 252 | || GET_CODE (body) == CLOBBER) |
| 253 | delete_insn (insn); |
| 254 | else |
| 255 | |
| 256 | /* Detect and delete no-op move instructions |
| 257 | resulting from not allocating a parameter in a register. */ |
| 258 | |
| 259 | if (GET_CODE (body) == SET |
| 260 | && (SET_DEST (body) == SET_SRC (body) |
| 261 | || (GET_CODE (SET_DEST (body)) == MEM |
| 262 | && GET_CODE (SET_SRC (body)) == MEM |
| 263 | && rtx_equal_p (SET_SRC (body), SET_DEST (body)))) |
| 264 | && ! (GET_CODE (SET_DEST (body)) == MEM |
| 265 | && MEM_VOLATILE_P (SET_DEST (body))) |
| 266 | && ! (GET_CODE (SET_SRC (body)) == MEM |
| 267 | && MEM_VOLATILE_P (SET_SRC (body)))) |
| 268 | delete_insn (insn); |
| 269 | |
| 270 | /* Detect and ignore no-op move instructions |
| 271 | resulting from smart or fortuitous register allocation. */ |
| 272 | |
| 273 | else if (GET_CODE (body) == SET) |
| 274 | { |
| 275 | int sreg = true_regnum (SET_SRC (body)); |
| 276 | int dreg = true_regnum (SET_DEST (body)); |
| 277 | |
| 278 | if (sreg == dreg && sreg >= 0) |
| 279 | delete_insn (insn); |
| 280 | else if (sreg >= 0 && dreg >= 0) |
| 281 | { |
| 282 | rtx tem = find_equiv_reg (0, insn, 0, |
| 283 | sreg, 0, dreg, |
| 284 | GET_MODE (SET_SRC (body))); |
| 285 | |
| 286 | #ifdef PRESERVE_DEATH_INFO_REGNO_P |
| 287 | /* Deleting insn could lose a death-note for SREG or DREG |
| 288 | so don't do it if final needs accurate death-notes. */ |
| 289 | if (! PRESERVE_DEATH_INFO_REGNO_P (sreg) |
| 290 | && ! PRESERVE_DEATH_INFO_REGNO_P (dreg)) |
| 291 | #endif |
| 292 | if (tem != 0 |
| 293 | && GET_MODE (tem) == GET_MODE (SET_DEST (body))) |
| 294 | delete_insn (insn); |
| 295 | } |
| 296 | } |
| 297 | } |
| 298 | insn = next; |
| 299 | } |
| 300 | |
| 301 | /* Now iterate optimizing jumps until nothing changes over one pass. */ |
| 302 | changed = 1; |
| 303 | while (changed) |
| 304 | { |
| 305 | register rtx next; |
| 306 | changed = 0; |
| 307 | |
| 308 | for (insn = f; insn; insn = next) |
| 309 | { |
| 310 | #if 0 |
| 311 | /* If NOT the first iteration, if this is the last jump pass |
| 312 | (just before final), do the special peephole optimizations. |
| 313 | Avoiding the first iteration gives ordinary jump opts |
| 314 | a chance to work before peephole opts. */ |
| 315 | |
| 316 | if (noop_moves && !first && !flag_no_peephole) |
| 317 | if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN) |
| 318 | peephole (insn); |
| 319 | #endif |
| 320 | |
| 321 | /* That could have deleted some insns after INSN, so check now |
| 322 | what the following insn is. */ |
| 323 | |
| 324 | next = NEXT_INSN (insn); |
| 325 | |
| 326 | /* Tension the labels in dispatch tables. */ |
| 327 | |
| 328 | if (GET_CODE (insn) == JUMP_INSN) |
| 329 | { |
| 330 | if (GET_CODE (PATTERN (insn)) == ADDR_VEC) |
| 331 | changed |= tension_vector_labels (PATTERN (insn), 0, noop_moves); |
| 332 | if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) |
| 333 | changed |= tension_vector_labels (PATTERN (insn), 1, noop_moves); |
| 334 | } |
| 335 | |
| 336 | /* Don't allow dropping through into a dispatch table. |
| 337 | That means the dispatch insn itself was deleted, |
| 338 | so delete the table too. */ |
| 339 | |
| 340 | if (GET_CODE (insn) == JUMP_INSN) |
| 341 | { |
| 342 | /* Note: the corresponding job for ADDR_VEC is done |
| 343 | in delete_insn. */ |
| 344 | |
| 345 | /* A vector of offsets is unused if its label |
| 346 | is used only once (i.e., from the vector). */ |
| 347 | if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC |
| 348 | && LABEL_NUSES (XEXP (XEXP (PATTERN (insn), 0), 0)) == 1) |
| 349 | { |
| 350 | /* So delete both label and vector. */ |
| 351 | delete_insn (PREV_INSN (insn)); |
| 352 | delete_insn (insn); |
| 353 | changed = 1; |
| 354 | } |
| 355 | } |
| 356 | |
| 357 | if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn)) |
| 358 | { |
| 359 | register rtx reallabelprev = prev_real_insn (JUMP_LABEL (insn)); |
| 360 | rtx temp; |
| 361 | |
| 362 | /* Detect jump to following insn. */ |
| 363 | if (reallabelprev == insn && condjump_p (insn)) |
| 364 | { |
| 365 | delete_jump (insn); |
| 366 | changed = 1; |
| 367 | } |
| 368 | /* Detect worthless conditional jump. */ |
| 369 | else if ((temp = next_real_insn (insn)) |
| 370 | && GET_CODE (temp) == JUMP_INSN |
| 371 | && condjump_p (insn) |
| 372 | && simplejump_p (temp) |
| 373 | && JUMP_LABEL (insn) == JUMP_LABEL (temp)) |
| 374 | { |
| 375 | delete_jump (insn); |
| 376 | changed = 1; |
| 377 | next = NEXT_INSN (insn); |
| 378 | } |
| 379 | /* A jump to a return becomes a return. */ |
| 380 | else if (simplejump_p (insn) |
| 381 | && (temp = next_real_insn (JUMP_LABEL (insn))) != 0 |
| 382 | && GET_CODE (PATTERN (temp)) == RETURN) |
| 383 | { |
| 384 | PATTERN (insn) = PATTERN (temp); |
| 385 | /* Re-recognize this insn. */ |
| 386 | INSN_CODE (insn) = -1; |
| 387 | } |
| 388 | /* Detect jumping over an unconditional jump. */ |
| 389 | else if (reallabelprev != 0 |
| 390 | && GET_CODE (reallabelprev) == JUMP_INSN |
| 391 | && prev_real_insn (reallabelprev) == insn |
| 392 | && no_labels_between_p (insn, reallabelprev) |
| 393 | && simplejump_p (reallabelprev) |
| 394 | /* Ignore this if INSN is a hairy kind of jump, |
| 395 | since they may not be invertible. |
| 396 | This is conservative; could instead construct |
| 397 | the inverted insn and try recognizing it. */ |
| 398 | && condjump_p (insn)) |
| 399 | { |
| 400 | /* Delete the original unconditional jump (and barrier). */ |
| 401 | /* But don't let its destination go with it. */ |
| 402 | ++LABEL_NUSES (JUMP_LABEL (reallabelprev)); |
| 403 | delete_insn (reallabelprev); |
| 404 | /* Now change the condition, and make it go to the |
| 405 | place the deleted jump went to. |
| 406 | This may cause the label after the deletion to go away. |
| 407 | But now that the unconditional jump and its barrier |
| 408 | are gone, that is ok. */ |
| 409 | invert_jump (insn, JUMP_LABEL (reallabelprev)); |
| 410 | --LABEL_NUSES (JUMP_LABEL (reallabelprev)); |
| 411 | next = insn; |
| 412 | changed = 1; |
| 413 | } |
| 414 | else |
| 415 | { |
| 416 | /* Detect a jump to a jump. */ |
| 417 | { |
| 418 | register rtx nlabel |
| 419 | = follow_jumps (JUMP_LABEL (insn), noop_moves); |
| 420 | if (nlabel != JUMP_LABEL (insn)) |
| 421 | { |
| 422 | redirect_jump (insn, nlabel); |
| 423 | changed = 1; |
| 424 | next = insn; |
| 425 | } |
| 426 | } |
| 427 | |
| 428 | /* Look for if (foo) bar; else break; */ |
| 429 | /* The insns look like this: |
| 430 | insn = condjump label1; |
| 431 | ...range1 (some insns)... |
| 432 | jump label2; |
| 433 | label1: |
| 434 | ...range2 (some insns)... |
| 435 | jump somewhere unconditionally |
| 436 | label2: */ |
| 437 | { |
| 438 | rtx label1 = next_label (insn); |
| 439 | rtx range1end = label1 ? prev_real_insn (label1) : 0; |
| 440 | /* Don't do this optimization on the first round, so that |
| 441 | jump-around-a-jump gets simplified before we ask here |
| 442 | whether a jump is unconditional. */ |
| 443 | if (! first |
| 444 | /* Make sure INSN is something we can invert. */ |
| 445 | && condjump_p (insn) |
| 446 | && JUMP_LABEL (insn) == label1 |
| 447 | && LABEL_NUSES (label1) == 1 |
| 448 | && GET_CODE (range1end) == JUMP_INSN |
| 449 | && simplejump_p (range1end)) |
| 450 | { |
| 451 | rtx label2 = next_label (label1); |
| 452 | rtx range2end = label2 ? prev_real_insn (label2) : 0; |
| 453 | if (range1end != range2end |
| 454 | && JUMP_LABEL (range1end) == label2 |
| 455 | && GET_CODE (range2end) == JUMP_INSN |
| 456 | && GET_CODE (NEXT_INSN (range2end)) == BARRIER) |
| 457 | { |
| 458 | rtx range1beg = next_real_insn (insn); |
| 459 | rtx range2beg = next_real_insn (label1); |
| 460 | rtx range1after, range2after; |
| 461 | rtx range1before, range2before; |
| 462 | |
| 463 | /* Don't move NOTEs for blocks; shift them |
| 464 | outside the ranges, where they'll stay put. */ |
| 465 | squeeze_block_notes (range1beg, range1end); |
| 466 | squeeze_block_notes (range2beg, range2end); |
| 467 | |
| 468 | /* Get current surrounds of the 2 ranges. */ |
| 469 | range1before = PREV_INSN (range1beg); |
| 470 | range2before = PREV_INSN (range2beg); |
| 471 | range1after = NEXT_INSN (range1end); |
| 472 | range2after = NEXT_INSN (range2end); |
| 473 | |
| 474 | /* Splice range2 where range1 was. */ |
| 475 | NEXT_INSN (range1before) = range2beg; |
| 476 | PREV_INSN (range2beg) = range1before; |
| 477 | NEXT_INSN (range2end) = range1after; |
| 478 | PREV_INSN (range1after) = range2end; |
| 479 | /* Splice range1 where range2 was. */ |
| 480 | NEXT_INSN (range2before) = range1beg; |
| 481 | PREV_INSN (range1beg) = range2before; |
| 482 | NEXT_INSN (range1end) = range2after; |
| 483 | PREV_INSN (range2after) = range1end; |
| 484 | /* Invert the jump condition, so we |
| 485 | still execute the same insns in each case. */ |
| 486 | invert_jump (insn, label1); |
| 487 | changed = 1; |
| 488 | continue; |
| 489 | } |
| 490 | } |
| 491 | } |
| 492 | |
| 493 | /* Now that the jump has been tensioned, |
| 494 | try cross jumping: check for identical code |
| 495 | before the jump and before its target label. */ |
| 496 | |
| 497 | /* First, cross jumping of conditional jumps: */ |
| 498 | |
| 499 | if (cross_jump && condjump_p (insn)) |
| 500 | { |
| 501 | rtx newjpos, newlpos; |
| 502 | rtx x = prev_real_insn (JUMP_LABEL (insn)); |
| 503 | |
| 504 | /* A conditional jump may be crossjumped |
| 505 | only if the place it jumps to follows |
| 506 | an opposing jump that comes back here. */ |
| 507 | |
| 508 | if (x != 0 && ! jump_back_p (x, insn)) |
| 509 | /* We have no opposing jump; |
| 510 | cannot cross jump this insn. */ |
| 511 | x = 0; |
| 512 | |
| 513 | newjpos = 0; |
| 514 | /* TARGET is nonzero if it is ok to cross jump |
| 515 | to code before TARGET. If so, see if matches. */ |
| 516 | if (x != 0) |
| 517 | find_cross_jump (insn, x, 2, |
| 518 | &newjpos, &newlpos); |
| 519 | |
| 520 | if (newjpos != 0) |
| 521 | { |
| 522 | do_cross_jump (insn, newjpos, newlpos); |
| 523 | /* Make the old conditional jump |
| 524 | into an unconditional one. */ |
| 525 | SET_SRC (PATTERN (insn)) |
| 526 | = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn)); |
| 527 | emit_barrier_after (insn); |
| 528 | changed = 1; |
| 529 | next = insn; |
| 530 | } |
| 531 | } |
| 532 | |
| 533 | /* Cross jumping of unconditional jumps: |
| 534 | a few differences. */ |
| 535 | |
| 536 | if (cross_jump && simplejump_p (insn)) |
| 537 | { |
| 538 | rtx newjpos, newlpos; |
| 539 | rtx target; |
| 540 | |
| 541 | newjpos = 0; |
| 542 | |
| 543 | /* TARGET is nonzero if it is ok to cross jump |
| 544 | to code before TARGET. If so, see if matches. */ |
| 545 | find_cross_jump (insn, JUMP_LABEL (insn), 1, |
| 546 | &newjpos, &newlpos); |
| 547 | |
| 548 | /* If cannot cross jump to code before the label, |
| 549 | see if we can cross jump to another jump to |
| 550 | the same label. */ |
| 551 | /* Try each other jump to this label. */ |
| 552 | if (INSN_UID (JUMP_LABEL (insn)) < max_uid) |
| 553 | for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))]; |
| 554 | target != 0 && newjpos == 0; |
| 555 | target = jump_chain[INSN_UID (target)]) |
| 556 | if (target != insn |
| 557 | && JUMP_LABEL (target) == JUMP_LABEL (insn) |
| 558 | /* Ignore TARGET if it's deleted. */ |
| 559 | && ! INSN_DELETED_P (target)) |
| 560 | find_cross_jump (insn, target, 2, |
| 561 | &newjpos, &newlpos); |
| 562 | |
| 563 | if (newjpos != 0) |
| 564 | { |
| 565 | do_cross_jump (insn, newjpos, newlpos); |
| 566 | changed = 1; |
| 567 | next = insn; |
| 568 | } |
| 569 | } |
| 570 | } |
| 571 | } |
| 572 | else if (GET_CODE (insn) == JUMP_INSN |
| 573 | && GET_CODE (PATTERN (insn)) == RETURN) |
| 574 | { |
| 575 | /* Return insns all "jump to the same place" |
| 576 | so we can cross-jump between any two of them. */ |
| 577 | if (cross_jump) |
| 578 | { |
| 579 | rtx newjpos, newlpos, target; |
| 580 | |
| 581 | newjpos = 0; |
| 582 | |
| 583 | /* If cannot cross jump to code before the label, |
| 584 | see if we can cross jump to another jump to |
| 585 | the same label. */ |
| 586 | /* Try each other jump to this label. */ |
| 587 | for (target = jump_chain[0]; |
| 588 | target != 0 && newjpos == 0; |
| 589 | target = jump_chain[INSN_UID (target)]) |
| 590 | if (target != insn |
| 591 | && ! INSN_DELETED_P (target) |
| 592 | && GET_CODE (PATTERN (target)) == RETURN) |
| 593 | find_cross_jump (insn, target, 2, |
| 594 | &newjpos, &newlpos); |
| 595 | |
| 596 | if (newjpos != 0) |
| 597 | { |
| 598 | do_cross_jump (insn, newjpos, newlpos); |
| 599 | changed = 1; |
| 600 | next = insn; |
| 601 | } |
| 602 | } |
| 603 | } |
| 604 | |
| 605 | } |
| 606 | |
| 607 | first = 0; |
| 608 | } |
| 609 | |
| 610 | /* See if there is still a NOTE_INSN_FUNCTION_END in this function. |
| 611 | If so, delete it, and record that this function can drop off the end. */ |
| 612 | |
| 613 | insn = last_insn; |
| 614 | { |
| 615 | int n_labels = 1; |
| 616 | while (insn |
| 617 | /* One label can follow the end-note: the return label. */ |
| 618 | && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0) |
| 619 | /* Ordinary insns can follow it if returning a structure. */ |
| 620 | || GET_CODE (insn) == INSN |
| 621 | /* If machine uses explicit RETURN insns, no epilogue, |
| 622 | then one of them follows the note. */ |
| 623 | || (GET_CODE (insn) == JUMP_INSN |
| 624 | && GET_CODE (PATTERN (insn)) == RETURN) |
| 625 | /* Other kinds of notes can follow also. */ |
| 626 | || (GET_CODE (insn) == NOTE |
| 627 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END))) |
| 628 | insn = PREV_INSN (insn); |
| 629 | } |
| 630 | if (insn && GET_CODE (insn) == NOTE |
| 631 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END) |
| 632 | { |
| 633 | extern int current_function_returns_null; |
| 634 | current_function_returns_null = 1; |
| 635 | delete_insn (insn); |
| 636 | } |
| 637 | } |
| 638 | \f |
| 639 | /* Compare the instructions before insn E1 with those before E2. |
| 640 | Assume E1 is a jump that jumps to label E2 |
| 641 | (that is not always true but it might as well be). |
| 642 | Find the longest possible equivalent sequences |
| 643 | and store the first insns of those sequences into *F1 and *F2. |
| 644 | Store zero there if no equivalent preceding instructions are found. |
| 645 | |
| 646 | We give up if we find a label in stream 1. |
| 647 | Actually we could transfer that label into stream 2. */ |
| 648 | |
| 649 | static void |
| 650 | find_cross_jump (e1, e2, minimum, f1, f2) |
| 651 | rtx e1, e2; |
| 652 | int minimum; |
| 653 | rtx *f1, *f2; |
| 654 | { |
| 655 | register rtx i1 = e1, i2 = e2; |
| 656 | register rtx p1, p2; |
| 657 | |
| 658 | rtx last1 = 0, last2 = 0; |
| 659 | rtx afterlast1 = 0, afterlast2 = 0; |
| 660 | |
| 661 | *f1 = 0; |
| 662 | *f2 = 0; |
| 663 | |
| 664 | while (1) |
| 665 | { |
| 666 | i1 = PREV_INSN (i1); |
| 667 | while (i1 && GET_CODE (i1) == NOTE) |
| 668 | i1 = PREV_INSN (i1); |
| 669 | |
| 670 | i2 = PREV_INSN (i2); |
| 671 | while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL)) |
| 672 | i2 = PREV_INSN (i2); |
| 673 | |
| 674 | if (i1 == 0) |
| 675 | break; |
| 676 | |
| 677 | /* Don't allow the range of insns preceding E1 or E2 |
| 678 | to include the other (E2 or E1). */ |
| 679 | if (i2 == e1 || i1 == e2) |
| 680 | break; |
| 681 | |
| 682 | /* If we will get to this code by jumping, those jumps will be |
| 683 | tensioned to go directly to the new label (before I2), |
| 684 | so this cross-jumping won't cost extra. So reduce the minimum. */ |
| 685 | if (GET_CODE (i1) == CODE_LABEL) |
| 686 | { |
| 687 | --minimum; |
| 688 | break; |
| 689 | } |
| 690 | |
| 691 | if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2)) |
| 692 | break; |
| 693 | |
| 694 | p1 = PATTERN (i1); |
| 695 | p2 = PATTERN (i2); |
| 696 | |
| 697 | if (GET_CODE (p1) != GET_CODE (p2) |
| 698 | || !rtx_renumbered_equal_p (p1, p2)) |
| 699 | { |
| 700 | /* Insns fail to match; cross jumping is limited to the following |
| 701 | insns. */ |
| 702 | |
| 703 | /* Don't allow the insn after a compare to be shared by cross-jumping |
| 704 | unless the compare is also shared. |
| 705 | Here, if either of these non-matching insns is a compare, |
| 706 | exclude the following insn from possible cross-jumping. */ |
| 707 | if (sets_cc0_p (p1) || sets_cc0_p (p2)) |
| 708 | last1 = afterlast1, last2 = afterlast2, ++minimum; |
| 709 | |
| 710 | /* If cross-jumping here will feed a jump-around-jump optimization, |
| 711 | this jump won't cost extra, so reduce the minimum. */ |
| 712 | if (GET_CODE (i1) == JUMP_INSN |
| 713 | && JUMP_LABEL (i1) |
| 714 | && prev_real_insn (JUMP_LABEL (i1)) == e1) |
| 715 | --minimum; |
| 716 | break; |
| 717 | } |
| 718 | |
| 719 | if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER) |
| 720 | { |
| 721 | /* Ok, this insn is potentially includable in a cross-jump here. */ |
| 722 | afterlast1 = last1, afterlast2 = last2; |
| 723 | last1 = i1, last2 = i2, --minimum; |
| 724 | } |
| 725 | } |
| 726 | |
| 727 | if (minimum <= 0 && last1 != 0) |
| 728 | *f1 = last1, *f2 = last2; |
| 729 | } |
| 730 | |
| 731 | static void |
| 732 | do_cross_jump (insn, newjpos, newlpos) |
| 733 | rtx insn, newjpos, newlpos; |
| 734 | { |
| 735 | register rtx label; |
| 736 | /* Find an existing label at this point |
| 737 | or make a new one if there is none. */ |
| 738 | label = PREV_INSN (newlpos); |
| 739 | while (label && GET_CODE (label) == NOTE) |
| 740 | label = PREV_INSN (label); |
| 741 | |
| 742 | if (label == 0 || GET_CODE (label) != CODE_LABEL) |
| 743 | { |
| 744 | label = gen_label_rtx (); |
| 745 | emit_label_after (label, PREV_INSN (newlpos)); |
| 746 | LABEL_NUSES (label) = 0; |
| 747 | } |
| 748 | /* Make the same jump insn jump to the new point. */ |
| 749 | if (GET_CODE (PATTERN (insn)) == RETURN) |
| 750 | { |
| 751 | extern rtx gen_jump (); |
| 752 | PATTERN (insn) = gen_jump (label); |
| 753 | INSN_CODE (insn) = -1; |
| 754 | JUMP_LABEL (insn) = label; |
| 755 | LABEL_NUSES (label)++; |
| 756 | } |
| 757 | else |
| 758 | redirect_jump (insn, label); |
| 759 | /* Delete the matching insns before the jump. */ |
| 760 | newjpos = PREV_INSN (newjpos); |
| 761 | while (NEXT_INSN (newjpos) != insn) |
| 762 | /* Don't delete line numbers. */ |
| 763 | if (GET_CODE (NEXT_INSN (newjpos)) != NOTE) |
| 764 | delete_insn (NEXT_INSN (newjpos)); |
| 765 | else |
| 766 | newjpos = NEXT_INSN (newjpos); |
| 767 | } |
| 768 | \f |
| 769 | /* Move all block-beg and block-end notes between START and END |
| 770 | out before START. Assume neither START nor END is such a note. */ |
| 771 | |
| 772 | static void |
| 773 | squeeze_block_notes (start, end) |
| 774 | rtx start, end; |
| 775 | { |
| 776 | rtx insn; |
| 777 | rtx next; |
| 778 | |
| 779 | for (insn = start; insn != end; insn = next) |
| 780 | { |
| 781 | next = NEXT_INSN (insn); |
| 782 | if (GET_CODE (insn) == NOTE |
| 783 | && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END |
| 784 | || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)) |
| 785 | { |
| 786 | rtx prev = PREV_INSN (insn); |
| 787 | PREV_INSN (insn) = PREV_INSN (start); |
| 788 | NEXT_INSN (insn) = start; |
| 789 | NEXT_INSN (PREV_INSN (insn)) = insn; |
| 790 | PREV_INSN (NEXT_INSN (insn)) = insn; |
| 791 | NEXT_INSN (prev) = next; |
| 792 | PREV_INSN (next) = prev; |
| 793 | } |
| 794 | } |
| 795 | } |
| 796 | |
| 797 | /* Return 1 if INSN is a jump that jumps to right after TARGET |
| 798 | only on the condition that TARGET itself would drop through. |
| 799 | Assumes that TARGET is a conditional jump. */ |
| 800 | |
| 801 | static int |
| 802 | jump_back_p (insn, target) |
| 803 | rtx insn, target; |
| 804 | { |
| 805 | rtx cinsn, ctarget, prev; |
| 806 | enum rtx_code codei, codet; |
| 807 | |
| 808 | if (simplejump_p (insn) || ! condjump_p (insn) |
| 809 | || simplejump_p (target)) |
| 810 | return 0; |
| 811 | if (target != prev_real_insn (JUMP_LABEL (insn))) |
| 812 | return 0; |
| 813 | |
| 814 | /* Verify that the condition code was based on a fixed-point computation. |
| 815 | Using reverse_condition is invalid for IEEE floating point with nans. */ |
| 816 | prev = prev_real_insn (insn); |
| 817 | if (! (prev != 0 |
| 818 | && GET_CODE (prev) == INSN |
| 819 | && GET_CODE (PATTERN (prev)) == SET |
| 820 | && SET_DEST (PATTERN (prev)) == cc0_rtx |
| 821 | && (GET_MODE_CLASS (GET_MODE (SET_SRC (PATTERN (prev)))) == MODE_INT |
| 822 | || (GET_CODE (SET_SRC (PATTERN (prev))) == COMPARE |
| 823 | && (GET_MODE_CLASS (GET_MODE (XEXP (SET_SRC (PATTERN (prev)), 0))) |
| 824 | == MODE_INT))))) |
| 825 | return 0; |
| 826 | |
| 827 | cinsn = XEXP (SET_SRC (PATTERN (insn)), 0); |
| 828 | ctarget = XEXP (SET_SRC (PATTERN (target)), 0); |
| 829 | |
| 830 | codei = GET_CODE (cinsn); |
| 831 | codet = GET_CODE (ctarget); |
| 832 | if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx) |
| 833 | |
| 834 | codei = reverse_condition (codei); |
| 835 | if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx) |
| 836 | codet = reverse_condition (codet); |
| 837 | return (codei == codet |
| 838 | && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0)) |
| 839 | && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1))); |
| 840 | } |
| 841 | |
| 842 | /* Given an rtx-code for a comparison, return the code |
| 843 | for the negated comparison. |
| 844 | WATCH OUT! reverse_condition is not safe to use on a jump |
| 845 | that might be acting on the results of an IEEE floating point comparison, |
| 846 | because of the special treatment of non-signaling nans in comparisons. */ |
| 847 | |
| 848 | static enum rtx_code |
| 849 | reverse_condition (code) |
| 850 | enum rtx_code code; |
| 851 | { |
| 852 | switch (code) |
| 853 | { |
| 854 | case EQ: |
| 855 | return NE; |
| 856 | |
| 857 | case NE: |
| 858 | return EQ; |
| 859 | |
| 860 | case GT: |
| 861 | return LE; |
| 862 | |
| 863 | case GE: |
| 864 | return LT; |
| 865 | |
| 866 | case LT: |
| 867 | return GE; |
| 868 | |
| 869 | case LE: |
| 870 | return GT; |
| 871 | |
| 872 | case GTU: |
| 873 | return LEU; |
| 874 | |
| 875 | case GEU: |
| 876 | return LTU; |
| 877 | |
| 878 | case LTU: |
| 879 | return GEU; |
| 880 | |
| 881 | case LEU: |
| 882 | return GTU; |
| 883 | |
| 884 | default: |
| 885 | abort (); |
| 886 | return UNKNOWN; |
| 887 | } |
| 888 | } |
| 889 | \f |
| 890 | /* Return 1 if INSN is an unconditional jump and nothing else. */ |
| 891 | |
| 892 | int |
| 893 | simplejump_p (insn) |
| 894 | rtx insn; |
| 895 | { |
| 896 | register rtx x = PATTERN (insn); |
| 897 | if (GET_CODE (x) != SET) |
| 898 | return 0; |
| 899 | if (GET_CODE (SET_DEST (x)) != PC) |
| 900 | return 0; |
| 901 | if (GET_CODE (SET_SRC (x)) != LABEL_REF) |
| 902 | return 0; |
| 903 | return 1; |
| 904 | } |
| 905 | |
| 906 | /* Return nonzero if INSN is a (possibly) conditional jump |
| 907 | and nothing more. */ |
| 908 | |
| 909 | int |
| 910 | condjump_p (insn) |
| 911 | rtx insn; |
| 912 | { |
| 913 | register rtx x = PATTERN (insn); |
| 914 | if (GET_CODE (x) != SET) |
| 915 | return 0; |
| 916 | if (GET_CODE (SET_DEST (x)) != PC) |
| 917 | return 0; |
| 918 | if (GET_CODE (SET_SRC (x)) == LABEL_REF) |
| 919 | return 1; |
| 920 | if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE) |
| 921 | return 0; |
| 922 | if (XEXP (SET_SRC (x), 2) == pc_rtx |
| 923 | && GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF) |
| 924 | return 1; |
| 925 | if (XEXP (SET_SRC (x), 1) == pc_rtx |
| 926 | && GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF) |
| 927 | return 1; |
| 928 | return 0; |
| 929 | } |
| 930 | |
| 931 | /* Return 1 if X is an RTX that does nothing but set the condition codes |
| 932 | and CLOBBER or USE registers. |
| 933 | Return -1 if X does explicitly set the condition codes, |
| 934 | but also does other things. */ |
| 935 | |
| 936 | int |
| 937 | sets_cc0_p (x) |
| 938 | rtx x; |
| 939 | { |
| 940 | if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx) |
| 941 | return 1; |
| 942 | if (GET_CODE (x) == PARALLEL) |
| 943 | { |
| 944 | int i; |
| 945 | int sets_cc0 = 0; |
| 946 | int other_things = 0; |
| 947 | for (i = XVECLEN (x, 0) - 1; i >= 0; i--) |
| 948 | { |
| 949 | if (GET_CODE (XVECEXP (x, 0, i)) == SET |
| 950 | && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx) |
| 951 | sets_cc0 = 1; |
| 952 | else if (GET_CODE (XVECEXP (x, 0, i)) == SET) |
| 953 | other_things = 1; |
| 954 | } |
| 955 | return ! sets_cc0 ? 0 : other_things ? -1 : 1; |
| 956 | } |
| 957 | return 0; |
| 958 | } |
| 959 | |
| 960 | /* Return 1 if in between BEG and END there is no CODE_LABEL insn. */ |
| 961 | |
| 962 | int |
| 963 | no_labels_between_p (beg, end) |
| 964 | rtx beg, end; |
| 965 | { |
| 966 | register rtx p; |
| 967 | for (p = beg; p != end; p = NEXT_INSN (p)) |
| 968 | if (GET_CODE (p) == CODE_LABEL) |
| 969 | return 0; |
| 970 | return 1; |
| 971 | } |
| 972 | \f |
| 973 | /* Return the last INSN, CALL_INSN or JUMP_INSN before LABEL; |
| 974 | or 0, if there is none. */ |
| 975 | |
| 976 | rtx |
| 977 | prev_real_insn (label) |
| 978 | rtx label; |
| 979 | { |
| 980 | register rtx insn = PREV_INSN (label); |
| 981 | register RTX_CODE code; |
| 982 | |
| 983 | while (1) |
| 984 | { |
| 985 | if (insn == 0) |
| 986 | return 0; |
| 987 | code = GET_CODE (insn); |
| 988 | if (code == INSN || code == CALL_INSN || code == JUMP_INSN) |
| 989 | break; |
| 990 | insn = PREV_INSN (insn); |
| 991 | } |
| 992 | |
| 993 | return insn; |
| 994 | } |
| 995 | |
| 996 | /* Return the next INSN, CALL_INSN or JUMP_INSN after LABEL; |
| 997 | or 0, if there is none. */ |
| 998 | |
| 999 | rtx |
| 1000 | next_real_insn (label) |
| 1001 | rtx label; |
| 1002 | { |
| 1003 | register rtx insn = NEXT_INSN (label); |
| 1004 | register RTX_CODE code; |
| 1005 | |
| 1006 | while (1) |
| 1007 | { |
| 1008 | if (insn == 0) |
| 1009 | return insn; |
| 1010 | code = GET_CODE (insn); |
| 1011 | if (code == INSN || code == CALL_INSN || code == JUMP_INSN) |
| 1012 | break; |
| 1013 | insn = NEXT_INSN (insn); |
| 1014 | } |
| 1015 | |
| 1016 | return insn; |
| 1017 | } |
| 1018 | |
| 1019 | /* Return the next CODE_LABEL after the insn INSN, or 0 if there is none. */ |
| 1020 | |
| 1021 | rtx |
| 1022 | next_label (insn) |
| 1023 | rtx insn; |
| 1024 | { |
| 1025 | do insn = NEXT_INSN (insn); |
| 1026 | while (insn != 0 && GET_CODE (insn) != CODE_LABEL); |
| 1027 | return insn; |
| 1028 | } |
| 1029 | \f |
| 1030 | /* Follow any unconditional jump at LABEL; |
| 1031 | return the ultimate label reached by any such chain of jumps. |
| 1032 | If LABEL is not followed by a jump, return LABEL. |
| 1033 | If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */ |
| 1034 | |
| 1035 | static rtx |
| 1036 | follow_jumps (label, ignore_loops) |
| 1037 | rtx label; |
| 1038 | int ignore_loops; |
| 1039 | { |
| 1040 | register rtx insn; |
| 1041 | register rtx next; |
| 1042 | register rtx value = label; |
| 1043 | register int depth; |
| 1044 | |
| 1045 | for (depth = 0; |
| 1046 | (depth < 10 |
| 1047 | && (insn = next_real_insn (value)) != 0 |
| 1048 | && GET_CODE (insn) == JUMP_INSN |
| 1049 | && JUMP_LABEL (insn) != 0 |
| 1050 | && (next = NEXT_INSN (insn)) |
| 1051 | && GET_CODE (next) == BARRIER); |
| 1052 | depth++) |
| 1053 | { |
| 1054 | /* Don't chain through the insn that jumps into a loop |
| 1055 | from outside the loop, |
| 1056 | since that would create multiple loop entry jumps |
| 1057 | and prevent loop optimization. */ |
| 1058 | rtx tem; |
| 1059 | if (!ignore_loops) |
| 1060 | for (tem = value; tem != insn; tem = NEXT_INSN (tem)) |
| 1061 | if (GET_CODE (tem) == NOTE |
| 1062 | && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG) |
| 1063 | return value; |
| 1064 | |
| 1065 | /* If we have found a cycle, make the insn jump to itself. */ |
| 1066 | if (JUMP_LABEL (insn) == label) |
| 1067 | break; |
| 1068 | value = JUMP_LABEL (insn); |
| 1069 | } |
| 1070 | return value; |
| 1071 | } |
| 1072 | |
| 1073 | /* Assuming that field IDX of X is a vector of label_refs, |
| 1074 | replace each of them by the ultimate label reached by it. |
| 1075 | Return nonzero if a change is made. |
| 1076 | If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */ |
| 1077 | |
| 1078 | static int |
| 1079 | tension_vector_labels (x, idx, ignore_loops) |
| 1080 | register rtx x; |
| 1081 | register int idx; |
| 1082 | int ignore_loops; |
| 1083 | { |
| 1084 | int changed = 0; |
| 1085 | register int i; |
| 1086 | for (i = XVECLEN (x, idx) - 1; i >= 0; i--) |
| 1087 | { |
| 1088 | register rtx olabel = XEXP (XVECEXP (x, idx, i), 0); |
| 1089 | register rtx nlabel = follow_jumps (olabel, ignore_loops); |
| 1090 | if (nlabel != olabel) |
| 1091 | { |
| 1092 | XEXP (XVECEXP (x, idx, i), 0) = nlabel; |
| 1093 | ++LABEL_NUSES (nlabel); |
| 1094 | if (--LABEL_NUSES (olabel) == 0) |
| 1095 | delete_insn (olabel); |
| 1096 | changed = 1; |
| 1097 | } |
| 1098 | } |
| 1099 | return changed; |
| 1100 | } |
| 1101 | \f |
| 1102 | /* Find all CODE_LABELs referred to in X, |
| 1103 | and increment their use counts. |
| 1104 | Also store one of them in JUMP_LABEL (INSN) if INSN is nonzero. |
| 1105 | Also, when there are consecutive labels, |
| 1106 | canonicalize on the last of them. |
| 1107 | |
| 1108 | Note that two labels separated by a loop-beginning note |
| 1109 | must be kept distinct if we have not yet done loop-optimization, |
| 1110 | because the gap between them is where loop-optimize |
| 1111 | will want to move invariant code to. CROSS_JUMP tells us |
| 1112 | that loop-optimization is done with. */ |
| 1113 | |
| 1114 | static void |
| 1115 | mark_jump_label (x, insn, cross_jump) |
| 1116 | register rtx x; |
| 1117 | rtx insn; |
| 1118 | int cross_jump; |
| 1119 | { |
| 1120 | register RTX_CODE code = GET_CODE (x); |
| 1121 | register int i; |
| 1122 | register char *fmt; |
| 1123 | |
| 1124 | if (code == LABEL_REF) |
| 1125 | { |
| 1126 | register rtx label = XEXP (x, 0); |
| 1127 | register rtx next; |
| 1128 | if (GET_CODE (label) != CODE_LABEL) |
| 1129 | return; |
| 1130 | /* If there are other labels following this one, |
| 1131 | replace it with the last of the consecutive labels. */ |
| 1132 | for (next = NEXT_INSN (label); next; next = NEXT_INSN (next)) |
| 1133 | { |
| 1134 | if (GET_CODE (next) == CODE_LABEL) |
| 1135 | label = next; |
| 1136 | else if (GET_CODE (next) != NOTE |
| 1137 | || NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG |
| 1138 | || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END) |
| 1139 | break; |
| 1140 | } |
| 1141 | XEXP (x, 0) = label; |
| 1142 | ++LABEL_NUSES (label); |
| 1143 | if (insn) |
| 1144 | JUMP_LABEL (insn) = label; |
| 1145 | return; |
| 1146 | } |
| 1147 | |
| 1148 | /* Do walk the labels in a vector, |
| 1149 | but don't set its JUMP_LABEL. */ |
| 1150 | if (code == ADDR_VEC || code == ADDR_DIFF_VEC) |
| 1151 | insn = 0; |
| 1152 | |
| 1153 | fmt = GET_RTX_FORMAT (code); |
| 1154 | for (i = GET_RTX_LENGTH (code); i >= 0; i--) |
| 1155 | { |
| 1156 | if (fmt[i] == 'e') |
| 1157 | mark_jump_label (XEXP (x, i), insn, cross_jump); |
| 1158 | else if (fmt[i] == 'E') |
| 1159 | { |
| 1160 | register int j; |
| 1161 | for (j = 0; j < XVECLEN (x, i); j++) |
| 1162 | mark_jump_label (XVECEXP (x, i, j), insn, cross_jump); |
| 1163 | } |
| 1164 | } |
| 1165 | } |
| 1166 | \f |
| 1167 | /* If all INSN does is set the pc, delete it, |
| 1168 | and delete the insn that set the condition codes for it |
| 1169 | if that's what the previous thing was. */ |
| 1170 | |
| 1171 | static void |
| 1172 | delete_jump (insn) |
| 1173 | rtx insn; |
| 1174 | { |
| 1175 | register rtx x = PATTERN (insn); |
| 1176 | register rtx prev; |
| 1177 | |
| 1178 | if (GET_CODE (x) == SET |
| 1179 | && GET_CODE (SET_DEST (x)) == PC) |
| 1180 | { |
| 1181 | prev = PREV_INSN (insn); |
| 1182 | delete_insn (insn); |
| 1183 | /* We assume that at this stage |
| 1184 | CC's are always set explicitly |
| 1185 | and always immediately before the jump that |
| 1186 | will use them. So if the previous insn |
| 1187 | exists to set the CC's, delete it |
| 1188 | (unless it performs auto-increments, etc.). */ |
| 1189 | while (prev && GET_CODE (prev) == NOTE) |
| 1190 | prev = PREV_INSN (prev); |
| 1191 | if (prev && GET_CODE (prev) == INSN |
| 1192 | && sets_cc0_p (PATTERN (prev)) > 0 |
| 1193 | && !find_reg_note (prev, REG_INC, 0)) |
| 1194 | delete_insn (prev); |
| 1195 | } |
| 1196 | } |
| 1197 | \f |
| 1198 | /* Delete insn INSN from the chain of insns and update label ref counts. |
| 1199 | May delete some following insns as a consequence; may even delete |
| 1200 | a label elsewhere and insns that follow it. |
| 1201 | |
| 1202 | Returns the first insn after INSN that was not deleted. */ |
| 1203 | |
| 1204 | rtx |
| 1205 | delete_insn (insn) |
| 1206 | register rtx insn; |
| 1207 | { |
| 1208 | register rtx next = NEXT_INSN (insn); |
| 1209 | register rtx prev = PREV_INSN (insn); |
| 1210 | |
| 1211 | while (next && INSN_DELETED_P (next)) |
| 1212 | next = NEXT_INSN (next); |
| 1213 | |
| 1214 | /* This insn is already deleted => return first following nondeleted. */ |
| 1215 | if (INSN_DELETED_P (insn)) |
| 1216 | return next; |
| 1217 | |
| 1218 | /* Mark this insn as deleted. */ |
| 1219 | |
| 1220 | INSN_DELETED_P (insn) = 1; |
| 1221 | |
| 1222 | /* If instruction is followed by a barrier, |
| 1223 | delete the barrier too. */ |
| 1224 | |
| 1225 | if (next != 0 && GET_CODE (next) == BARRIER) |
| 1226 | { |
| 1227 | INSN_DELETED_P (next) = 1; |
| 1228 | next = NEXT_INSN (next); |
| 1229 | } |
| 1230 | |
| 1231 | /* Patch out INSN (and the barrier if any) */ |
| 1232 | |
| 1233 | if (optimize) |
| 1234 | { |
| 1235 | if (prev) |
| 1236 | NEXT_INSN (prev) = next; |
| 1237 | |
| 1238 | if (next) |
| 1239 | PREV_INSN (next)= prev; |
| 1240 | |
| 1241 | if (prev && NEXT_INSN (prev) == 0) |
| 1242 | set_last_insn (prev); |
| 1243 | } |
| 1244 | |
| 1245 | /* If deleting a jump, decrement the count of the label, |
| 1246 | and delete the label if it is now unused. */ |
| 1247 | |
| 1248 | if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn)) |
| 1249 | if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0) |
| 1250 | { |
| 1251 | /* This can delete NEXT or PREV, |
| 1252 | either directly if NEXT is JUMP_LABEL (INSN), |
| 1253 | or indirectly through more levels of jumps. */ |
| 1254 | delete_insn (JUMP_LABEL (insn)); |
| 1255 | /* I feel a little doubtful about this loop, |
| 1256 | but I see no clean and sure alternative way |
| 1257 | to find the first insn after INSN that is not now deleted. |
| 1258 | I hope this works. */ |
| 1259 | while (next && INSN_DELETED_P (next)) |
| 1260 | next = NEXT_INSN (next); |
| 1261 | return next; |
| 1262 | } |
| 1263 | |
| 1264 | while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE)) |
| 1265 | prev = PREV_INSN (prev); |
| 1266 | |
| 1267 | /* If INSN was a label and a dispatch table follows it, |
| 1268 | delete the dispatch table. The tablejump must have gone already. |
| 1269 | It isn't useful to fall through into a table. */ |
| 1270 | |
| 1271 | if (GET_CODE (insn) == CODE_LABEL |
| 1272 | && NEXT_INSN (insn) != 0 |
| 1273 | && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN |
| 1274 | && GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC) |
| 1275 | next = delete_insn (NEXT_INSN (insn)); |
| 1276 | |
| 1277 | /* If INSN was a label, delete insns following it if now unreachable. */ |
| 1278 | |
| 1279 | if (GET_CODE (insn) == CODE_LABEL && prev |
| 1280 | && GET_CODE (prev) == BARRIER) |
| 1281 | { |
| 1282 | register RTX_CODE code; |
| 1283 | while (next != 0 |
| 1284 | && ((code = GET_CODE (next)) == INSN |
| 1285 | || code == JUMP_INSN || code == CALL_INSN |
| 1286 | || code == NOTE)) |
| 1287 | { |
| 1288 | if (code == NOTE |
| 1289 | && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END) |
| 1290 | next = NEXT_INSN (next); |
| 1291 | else |
| 1292 | /* Note: if this deletes a jump, it can cause more |
| 1293 | deletion of unreachable code, after a different label. |
| 1294 | As long as the value from this recursive call is correct, |
| 1295 | this invocation functions correctly. */ |
| 1296 | next = delete_insn (next); |
| 1297 | } |
| 1298 | } |
| 1299 | |
| 1300 | return next; |
| 1301 | } |
| 1302 | |
| 1303 | /* Advance from INSN till reaching something not deleted |
| 1304 | then return that. May return INSN itself. */ |
| 1305 | |
| 1306 | rtx |
| 1307 | next_nondeleted_insn (insn) |
| 1308 | rtx insn; |
| 1309 | { |
| 1310 | while (INSN_DELETED_P (insn)) |
| 1311 | insn = NEXT_INSN (insn); |
| 1312 | return insn; |
| 1313 | } |
| 1314 | \f |
| 1315 | /* Delete a range of insns from FROM to TO, inclusive. |
| 1316 | This is for the sake of peephole optimization, so assume |
| 1317 | that whatever these insns do will still be done by a new |
| 1318 | peephole insn that will replace them. */ |
| 1319 | |
| 1320 | void |
| 1321 | delete_for_peephole (from, to) |
| 1322 | register rtx from, to; |
| 1323 | { |
| 1324 | register rtx insn = from; |
| 1325 | |
| 1326 | while (1) |
| 1327 | { |
| 1328 | register rtx next = NEXT_INSN (insn); |
| 1329 | register rtx prev = PREV_INSN (insn); |
| 1330 | |
| 1331 | if (GET_CODE (insn) != NOTE) |
| 1332 | { |
| 1333 | INSN_DELETED_P (insn) = 1; |
| 1334 | |
| 1335 | /* Patch this insn out of the chain. */ |
| 1336 | /* We don't do this all at once, because we |
| 1337 | must preserve all NOTEs. */ |
| 1338 | if (prev) |
| 1339 | NEXT_INSN (prev) = next; |
| 1340 | |
| 1341 | if (next) |
| 1342 | PREV_INSN (next) = prev; |
| 1343 | } |
| 1344 | |
| 1345 | if (insn == to) |
| 1346 | break; |
| 1347 | insn = next; |
| 1348 | } |
| 1349 | |
| 1350 | /* Note that if TO is an unconditional jump |
| 1351 | we *do not* delete the BARRIER that follows, |
| 1352 | since the peephole that replaces this sequence |
| 1353 | is also an unconditional jump in that case. */ |
| 1354 | } |
| 1355 | \f |
| 1356 | /* Invert the condition of the jump JUMP, and make it jump |
| 1357 | to label NLABEL instead of where it jumps now. */ |
| 1358 | |
| 1359 | void |
| 1360 | invert_jump (jump, nlabel) |
| 1361 | rtx jump, nlabel; |
| 1362 | { |
| 1363 | register rtx olabel = JUMP_LABEL (jump); |
| 1364 | invert_exp (PATTERN (jump), olabel, nlabel); |
| 1365 | JUMP_LABEL (jump) = nlabel; |
| 1366 | ++LABEL_NUSES (nlabel); |
| 1367 | INSN_CODE (jump) = -1; |
| 1368 | |
| 1369 | if (--LABEL_NUSES (olabel) == 0) |
| 1370 | delete_insn (olabel); |
| 1371 | } |
| 1372 | |
| 1373 | /* Invert the jump condition of rtx X, |
| 1374 | and replace OLABEL with NLABEL throughout. |
| 1375 | This is used in do_jump as well as in this file. */ |
| 1376 | |
| 1377 | void |
| 1378 | invert_exp (x, olabel, nlabel) |
| 1379 | rtx x; |
| 1380 | rtx olabel, nlabel; |
| 1381 | { |
| 1382 | register RTX_CODE code; |
| 1383 | register int i; |
| 1384 | register char *fmt; |
| 1385 | |
| 1386 | if (x == 0) |
| 1387 | return; |
| 1388 | |
| 1389 | code = GET_CODE (x); |
| 1390 | if (code == IF_THEN_ELSE) |
| 1391 | { |
| 1392 | /* Inverting the jump condition of an IF_THEN_ELSE |
| 1393 | means exchanging the THEN-part with the ELSE-part. */ |
| 1394 | register rtx tem = XEXP (x, 1); |
| 1395 | XEXP (x, 1) = XEXP (x, 2); |
| 1396 | XEXP (x, 2) = tem; |
| 1397 | } |
| 1398 | |
| 1399 | if (code == LABEL_REF) |
| 1400 | { |
| 1401 | if (XEXP (x, 0) == olabel) |
| 1402 | XEXP (x, 0) = nlabel; |
| 1403 | return; |
| 1404 | } |
| 1405 | |
| 1406 | fmt = GET_RTX_FORMAT (code); |
| 1407 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) |
| 1408 | { |
| 1409 | if (fmt[i] == 'e') |
| 1410 | invert_exp (XEXP (x, i), olabel, nlabel); |
| 1411 | if (fmt[i] == 'E') |
| 1412 | { |
| 1413 | register int j; |
| 1414 | for (j = 0; j < XVECLEN (x, i); j++) |
| 1415 | invert_exp (XVECEXP (x, i, j), olabel, nlabel); |
| 1416 | } |
| 1417 | } |
| 1418 | } |
| 1419 | \f |
| 1420 | /* Make jump JUMP jump to label NLABEL instead of where it jumps now. |
| 1421 | If the old jump target label is unused as a result, |
| 1422 | it and the code following it may be deleted. */ |
| 1423 | |
| 1424 | void |
| 1425 | redirect_jump (jump, nlabel) |
| 1426 | rtx jump, nlabel; |
| 1427 | { |
| 1428 | register rtx olabel = JUMP_LABEL (jump); |
| 1429 | |
| 1430 | if (nlabel == olabel) |
| 1431 | return; |
| 1432 | |
| 1433 | redirect_exp (PATTERN (jump), olabel, nlabel); |
| 1434 | JUMP_LABEL (jump) = nlabel; |
| 1435 | ++LABEL_NUSES (nlabel); |
| 1436 | INSN_CODE (jump) = -1; |
| 1437 | |
| 1438 | if (--LABEL_NUSES (olabel) == 0) |
| 1439 | delete_insn (olabel); |
| 1440 | } |
| 1441 | |
| 1442 | /* Throughout the rtx X, |
| 1443 | alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). */ |
| 1444 | |
| 1445 | static void |
| 1446 | redirect_exp (x, olabel, nlabel) |
| 1447 | rtx x; |
| 1448 | rtx olabel, nlabel; |
| 1449 | { |
| 1450 | register RTX_CODE code = GET_CODE (x); |
| 1451 | register int i; |
| 1452 | register char *fmt; |
| 1453 | |
| 1454 | if (code == LABEL_REF) |
| 1455 | { |
| 1456 | if (XEXP (x, 0) == olabel) |
| 1457 | XEXP (x, 0) = nlabel; |
| 1458 | return; |
| 1459 | } |
| 1460 | |
| 1461 | fmt = GET_RTX_FORMAT (code); |
| 1462 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) |
| 1463 | { |
| 1464 | if (fmt[i] == 'e') |
| 1465 | redirect_exp (XEXP (x, i), olabel, nlabel); |
| 1466 | if (fmt[i] == 'E') |
| 1467 | { |
| 1468 | register int j; |
| 1469 | for (j = 0; j < XVECLEN (x, i); j++) |
| 1470 | redirect_exp (XVECEXP (x, i, j), olabel, nlabel); |
| 1471 | } |
| 1472 | } |
| 1473 | } |
| 1474 | \f |
| 1475 | /* Like rtx_equal_p except that it considers two REGs as equal |
| 1476 | if they renumber to the same value. */ |
| 1477 | |
| 1478 | int |
| 1479 | rtx_renumbered_equal_p (x, y) |
| 1480 | rtx x, y; |
| 1481 | { |
| 1482 | register int i; |
| 1483 | register RTX_CODE code = GET_CODE (x); |
| 1484 | register char *fmt; |
| 1485 | |
| 1486 | if (x == y) |
| 1487 | return 1; |
| 1488 | if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG)) |
| 1489 | && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG |
| 1490 | && GET_CODE (SUBREG_REG (y)) == REG))) |
| 1491 | { |
| 1492 | register int j; |
| 1493 | |
| 1494 | if (GET_MODE (x) != GET_MODE (y)) |
| 1495 | return 0; |
| 1496 | |
| 1497 | if (code == SUBREG) |
| 1498 | { |
| 1499 | i = REGNO (SUBREG_REG (x)); |
| 1500 | if (reg_renumber[i] >= 0) |
| 1501 | i = reg_renumber[i]; |
| 1502 | i += SUBREG_WORD (x); |
| 1503 | } |
| 1504 | else |
| 1505 | { |
| 1506 | i = REGNO (x); |
| 1507 | if (reg_renumber[i] >= 0) |
| 1508 | i = reg_renumber[i]; |
| 1509 | } |
| 1510 | if (GET_CODE (y) == SUBREG) |
| 1511 | { |
| 1512 | j = REGNO (SUBREG_REG (y)); |
| 1513 | if (reg_renumber[j] >= 0) |
| 1514 | j = reg_renumber[j]; |
| 1515 | j += SUBREG_WORD (y); |
| 1516 | } |
| 1517 | else |
| 1518 | { |
| 1519 | j = REGNO (y); |
| 1520 | if (reg_renumber[j] >= 0) |
| 1521 | j = reg_renumber[j]; |
| 1522 | } |
| 1523 | return i == j; |
| 1524 | } |
| 1525 | /* Now we have disposed of all the cases |
| 1526 | in which different rtx codes can match. */ |
| 1527 | if (code != GET_CODE (y)) |
| 1528 | return 0; |
| 1529 | switch (code) |
| 1530 | { |
| 1531 | case PC: |
| 1532 | case CC0: |
| 1533 | case ADDR_VEC: |
| 1534 | case ADDR_DIFF_VEC: |
| 1535 | return 0; |
| 1536 | |
| 1537 | case CONST_INT: |
| 1538 | return XINT (x, 0) == XINT (y, 0); |
| 1539 | |
| 1540 | case LABEL_REF: |
| 1541 | /* Two label-refs are equivalent if they point at labels |
| 1542 | in the same position in the instruction stream. */ |
| 1543 | return (next_real_insn (XEXP (x, 0)) |
| 1544 | == next_real_insn (XEXP (y, 0))); |
| 1545 | |
| 1546 | case SYMBOL_REF: |
| 1547 | return XSTR (x, 0) == XSTR (y, 0); |
| 1548 | } |
| 1549 | |
| 1550 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ |
| 1551 | |
| 1552 | if (GET_MODE (x) != GET_MODE (y)) |
| 1553 | return 0; |
| 1554 | |
| 1555 | /* Compare the elements. If any pair of corresponding elements |
| 1556 | fail to match, return 0 for the whole things. */ |
| 1557 | |
| 1558 | fmt = GET_RTX_FORMAT (code); |
| 1559 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) |
| 1560 | { |
| 1561 | register int j; |
| 1562 | switch (fmt[i]) |
| 1563 | { |
| 1564 | case 'i': |
| 1565 | if (XINT (x, i) != XINT (y, i)) |
| 1566 | return 0; |
| 1567 | break; |
| 1568 | |
| 1569 | case 's': |
| 1570 | if (strcmp (XSTR (x, i), XSTR (y, i))) |
| 1571 | return 0; |
| 1572 | break; |
| 1573 | |
| 1574 | case 'e': |
| 1575 | if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i))) |
| 1576 | return 0; |
| 1577 | break; |
| 1578 | |
| 1579 | case '0': |
| 1580 | break; |
| 1581 | |
| 1582 | case 'E': |
| 1583 | if (XVECLEN (x, i) != XVECLEN (y, i)) |
| 1584 | return 0; |
| 1585 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) |
| 1586 | if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j))) |
| 1587 | return 0; |
| 1588 | break; |
| 1589 | |
| 1590 | default: |
| 1591 | abort (); |
| 1592 | } |
| 1593 | } |
| 1594 | return 1; |
| 1595 | } |
| 1596 | \f |
| 1597 | /* If X is a hard register or equivalent to one or a subregister of one, |
| 1598 | return the hard register number. Otherwise, return -1. |
| 1599 | Any rtx is valid for X. */ |
| 1600 | |
| 1601 | int |
| 1602 | true_regnum (x) |
| 1603 | rtx x; |
| 1604 | { |
| 1605 | if (GET_CODE (x) == REG) |
| 1606 | { |
| 1607 | if (REGNO (x) >= FIRST_PSEUDO_REGISTER) |
| 1608 | return reg_renumber[REGNO (x)]; |
| 1609 | return REGNO (x); |
| 1610 | } |
| 1611 | if (GET_CODE (x) == SUBREG) |
| 1612 | { |
| 1613 | int base = true_regnum (SUBREG_REG (x)); |
| 1614 | if (base >= 0 && base < FIRST_PSEUDO_REGISTER) |
| 1615 | return SUBREG_WORD (x) + base; |
| 1616 | } |
| 1617 | return -1; |
| 1618 | } |