Mercurial > hg > CbC > CbC_gcc
annotate gcc/cfgbuild.c @ 67:f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
| author | nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Tue, 22 Mar 2011 17:18:12 +0900 |
| parents | b7f97abdc517 |
| children | 04ced10e8804 |
| rev | line source |
|---|---|
| 0 | 1 /* Control flow graph building code for GNU compiler. |
| 2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, | |
|
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3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010 |
| 0 | 4 Free Software Foundation, Inc. |
| 5 | |
| 6 This file is part of GCC. | |
| 7 | |
| 8 GCC is free software; you can redistribute it and/or modify it under | |
| 9 the terms of the GNU General Public License as published by the Free | |
| 10 Software Foundation; either version 3, or (at your option) any later | |
| 11 version. | |
| 12 | |
| 13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
| 14 WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 16 for more details. | |
| 17 | |
| 18 You should have received a copy of the GNU General Public License | |
| 19 along with GCC; see the file COPYING3. If not see | |
| 20 <http://www.gnu.org/licenses/>. */ | |
| 21 | |
| 22 | |
| 23 #include "config.h" | |
| 24 #include "system.h" | |
| 25 #include "coretypes.h" | |
| 26 #include "tm.h" | |
| 27 #include "tree.h" | |
| 28 #include "rtl.h" | |
| 29 #include "hard-reg-set.h" | |
| 30 #include "basic-block.h" | |
| 31 #include "regs.h" | |
| 32 #include "flags.h" | |
| 33 #include "output.h" | |
| 34 #include "function.h" | |
| 35 #include "except.h" | |
|
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36 #include "expr.h" |
|
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37 #include "diagnostic-core.h" |
| 0 | 38 #include "timevar.h" |
|
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39 #include "sbitmap.h" |
| 0 | 40 |
| 41 static void make_edges (basic_block, basic_block, int); | |
| 42 static void make_label_edge (sbitmap, basic_block, rtx, int); | |
| 43 static void find_bb_boundaries (basic_block); | |
| 44 static void compute_outgoing_frequencies (basic_block); | |
| 45 | |
| 46 /* Return true if insn is something that should be contained inside basic | |
| 47 block. */ | |
| 48 | |
| 49 bool | |
| 50 inside_basic_block_p (const_rtx insn) | |
| 51 { | |
| 52 switch (GET_CODE (insn)) | |
| 53 { | |
| 54 case CODE_LABEL: | |
| 55 /* Avoid creating of basic block for jumptables. */ | |
| 56 return (NEXT_INSN (insn) == 0 | |
| 57 || !JUMP_P (NEXT_INSN (insn)) | |
| 58 || (GET_CODE (PATTERN (NEXT_INSN (insn))) != ADDR_VEC | |
| 59 && GET_CODE (PATTERN (NEXT_INSN (insn))) != ADDR_DIFF_VEC)); | |
| 60 | |
| 61 case JUMP_INSN: | |
| 62 return (GET_CODE (PATTERN (insn)) != ADDR_VEC | |
| 63 && GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC); | |
| 64 | |
| 65 case CALL_INSN: | |
| 66 case INSN: | |
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67 case DEBUG_INSN: |
| 0 | 68 return true; |
| 69 | |
| 70 case BARRIER: | |
| 71 case NOTE: | |
| 72 return false; | |
| 73 | |
| 74 default: | |
| 75 gcc_unreachable (); | |
| 76 } | |
| 77 } | |
| 78 | |
| 79 /* Return true if INSN may cause control flow transfer, so it should be last in | |
| 80 the basic block. */ | |
| 81 | |
| 82 bool | |
| 83 control_flow_insn_p (const_rtx insn) | |
| 84 { | |
| 85 switch (GET_CODE (insn)) | |
| 86 { | |
| 87 case NOTE: | |
| 88 case CODE_LABEL: | |
|
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89 case DEBUG_INSN: |
| 0 | 90 return false; |
| 91 | |
| 92 case JUMP_INSN: | |
| 93 /* Jump insn always causes control transfer except for tablejumps. */ | |
| 94 return (GET_CODE (PATTERN (insn)) != ADDR_VEC | |
| 95 && GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC); | |
| 96 | |
| 97 case CALL_INSN: | |
| 98 /* Noreturn and sibling call instructions terminate the basic blocks | |
| 99 (but only if they happen unconditionally). */ | |
| 100 if ((SIBLING_CALL_P (insn) | |
| 101 || find_reg_note (insn, REG_NORETURN, 0)) | |
| 102 && GET_CODE (PATTERN (insn)) != COND_EXEC) | |
| 103 return true; | |
|
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104 |
| 0 | 105 /* Call insn may return to the nonlocal goto handler. */ |
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106 if (can_nonlocal_goto (insn)) |
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107 return true; |
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108 break; |
| 0 | 109 |
| 110 case INSN: | |
| 111 /* Treat trap instructions like noreturn calls (same provision). */ | |
| 112 if (GET_CODE (PATTERN (insn)) == TRAP_IF | |
| 113 && XEXP (PATTERN (insn), 0) == const1_rtx) | |
| 114 return true; | |
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115 if (!cfun->can_throw_non_call_exceptions) |
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116 return false; |
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117 break; |
| 0 | 118 |
| 119 case BARRIER: | |
| 120 /* It is nonsense to reach barrier when looking for the | |
| 121 end of basic block, but before dead code is eliminated | |
| 122 this may happen. */ | |
| 123 return false; | |
| 124 | |
| 125 default: | |
| 126 gcc_unreachable (); | |
| 127 } | |
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128 |
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129 return can_throw_internal (insn); |
| 0 | 130 } |
| 131 | |
| 132 | |
| 133 /* Create an edge between two basic blocks. FLAGS are auxiliary information | |
| 134 about the edge that is accumulated between calls. */ | |
| 135 | |
| 136 /* Create an edge from a basic block to a label. */ | |
| 137 | |
| 138 static void | |
| 139 make_label_edge (sbitmap edge_cache, basic_block src, rtx label, int flags) | |
| 140 { | |
| 141 gcc_assert (LABEL_P (label)); | |
| 142 | |
| 143 /* If the label was never emitted, this insn is junk, but avoid a | |
| 144 crash trying to refer to BLOCK_FOR_INSN (label). This can happen | |
| 145 as a result of a syntax error and a diagnostic has already been | |
| 146 printed. */ | |
| 147 | |
| 148 if (INSN_UID (label) == 0) | |
| 149 return; | |
| 150 | |
| 151 cached_make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags); | |
| 152 } | |
| 153 | |
| 154 /* Create the edges generated by INSN in REGION. */ | |
| 155 | |
| 156 void | |
| 157 rtl_make_eh_edge (sbitmap edge_cache, basic_block src, rtx insn) | |
| 158 { | |
|
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159 eh_landing_pad lp = get_eh_landing_pad_from_rtx (insn); |
| 0 | 160 |
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161 if (lp) |
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162 { |
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163 rtx label = lp->landing_pad; |
| 0 | 164 |
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165 /* During initial rtl generation, use the post_landing_pad. */ |
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166 if (label == NULL) |
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167 { |
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168 gcc_assert (lp->post_landing_pad); |
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169 label = label_rtx (lp->post_landing_pad); |
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170 } |
| 0 | 171 |
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172 make_label_edge (edge_cache, src, label, |
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173 EDGE_ABNORMAL | EDGE_EH |
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174 | (CALL_P (insn) ? EDGE_ABNORMAL_CALL : 0)); |
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175 } |
| 0 | 176 } |
| 177 | |
| 178 /* States of basic block as seen by find_many_sub_basic_blocks. */ | |
| 179 enum state { | |
| 180 /* Basic blocks created via split_block belong to this state. | |
| 181 make_edges will examine these basic blocks to see if we need to | |
| 182 create edges going out of them. */ | |
| 183 BLOCK_NEW = 0, | |
| 184 | |
| 185 /* Basic blocks that do not need examining belong to this state. | |
| 186 These blocks will be left intact. In particular, make_edges will | |
| 187 not create edges going out of these basic blocks. */ | |
| 188 BLOCK_ORIGINAL, | |
| 189 | |
| 190 /* Basic blocks that may need splitting (due to a label appearing in | |
| 191 the middle, etc) belong to this state. After splitting them, | |
| 192 make_edges will create edges going out of them as needed. */ | |
| 193 BLOCK_TO_SPLIT | |
| 194 }; | |
| 195 | |
| 196 #define STATE(BB) (enum state) ((size_t) (BB)->aux) | |
| 197 #define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE)) | |
| 198 | |
| 199 /* Used internally by purge_dead_tablejump_edges, ORed into state. */ | |
| 200 #define BLOCK_USED_BY_TABLEJUMP 32 | |
| 201 #define FULL_STATE(BB) ((size_t) (BB)->aux) | |
| 202 | |
| 203 /* Identify the edges going out of basic blocks between MIN and MAX, | |
| 204 inclusive, that have their states set to BLOCK_NEW or | |
| 205 BLOCK_TO_SPLIT. | |
| 206 | |
| 207 UPDATE_P should be nonzero if we are updating CFG and zero if we | |
| 208 are building CFG from scratch. */ | |
| 209 | |
| 210 static void | |
| 211 make_edges (basic_block min, basic_block max, int update_p) | |
| 212 { | |
| 213 basic_block bb; | |
| 214 sbitmap edge_cache = NULL; | |
| 215 | |
| 216 /* Heavy use of computed goto in machine-generated code can lead to | |
| 217 nearly fully-connected CFGs. In that case we spend a significant | |
| 218 amount of time searching the edge lists for duplicates. */ | |
| 219 if (forced_labels || cfun->cfg->max_jumptable_ents > 100) | |
| 220 edge_cache = sbitmap_alloc (last_basic_block); | |
| 221 | |
| 222 /* By nature of the way these get numbered, ENTRY_BLOCK_PTR->next_bb block | |
| 223 is always the entry. */ | |
| 224 if (min == ENTRY_BLOCK_PTR->next_bb) | |
| 225 make_edge (ENTRY_BLOCK_PTR, min, EDGE_FALLTHRU); | |
| 226 | |
| 227 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb) | |
| 228 { | |
| 229 rtx insn, x; | |
| 230 enum rtx_code code; | |
| 231 edge e; | |
| 232 edge_iterator ei; | |
| 233 | |
| 234 if (STATE (bb) == BLOCK_ORIGINAL) | |
| 235 continue; | |
| 236 | |
| 237 /* If we have an edge cache, cache edges going out of BB. */ | |
| 238 if (edge_cache) | |
| 239 { | |
| 240 sbitmap_zero (edge_cache); | |
| 241 if (update_p) | |
| 242 { | |
| 243 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 244 if (e->dest != EXIT_BLOCK_PTR) | |
| 245 SET_BIT (edge_cache, e->dest->index); | |
| 246 } | |
| 247 } | |
| 248 | |
| 249 if (LABEL_P (BB_HEAD (bb)) | |
| 250 && LABEL_ALT_ENTRY_P (BB_HEAD (bb))) | |
| 251 cached_make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0); | |
| 252 | |
| 253 /* Examine the last instruction of the block, and discover the | |
| 254 ways we can leave the block. */ | |
| 255 | |
| 256 insn = BB_END (bb); | |
| 257 code = GET_CODE (insn); | |
| 258 | |
| 259 /* A branch. */ | |
| 260 if (code == JUMP_INSN) | |
| 261 { | |
| 262 rtx tmp; | |
| 263 | |
| 264 /* Recognize a non-local goto as a branch outside the | |
| 265 current function. */ | |
|
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266 if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX)) |
| 0 | 267 ; |
| 268 | |
| 269 /* Recognize a tablejump and do the right thing. */ | |
| 270 else if (tablejump_p (insn, NULL, &tmp)) | |
| 271 { | |
| 272 rtvec vec; | |
| 273 int j; | |
| 274 | |
| 275 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC) | |
| 276 vec = XVEC (PATTERN (tmp), 0); | |
| 277 else | |
| 278 vec = XVEC (PATTERN (tmp), 1); | |
| 279 | |
| 280 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) | |
| 281 make_label_edge (edge_cache, bb, | |
| 282 XEXP (RTVEC_ELT (vec, j), 0), 0); | |
| 283 | |
| 284 /* Some targets (eg, ARM) emit a conditional jump that also | |
| 285 contains the out-of-range target. Scan for these and | |
| 286 add an edge if necessary. */ | |
| 287 if ((tmp = single_set (insn)) != NULL | |
| 288 && SET_DEST (tmp) == pc_rtx | |
| 289 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE | |
| 290 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF) | |
| 291 make_label_edge (edge_cache, bb, | |
| 292 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0); | |
| 293 } | |
| 294 | |
| 295 /* If this is a computed jump, then mark it as reaching | |
| 296 everything on the forced_labels list. */ | |
| 297 else if (computed_jump_p (insn)) | |
| 298 { | |
| 299 for (x = forced_labels; x; x = XEXP (x, 1)) | |
| 300 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL); | |
| 301 } | |
| 302 | |
| 303 /* Returns create an exit out. */ | |
| 304 else if (returnjump_p (insn)) | |
| 305 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0); | |
| 306 | |
|
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307 /* Recognize asm goto and do the right thing. */ |
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308 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL) |
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309 { |
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310 int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp); |
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311 for (i = 0; i < n; ++i) |
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312 make_label_edge (edge_cache, bb, |
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313 XEXP (ASM_OPERANDS_LABEL (tmp, i), 0), 0); |
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314 } |
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315 |
| 0 | 316 /* Otherwise, we have a plain conditional or unconditional jump. */ |
| 317 else | |
| 318 { | |
| 319 gcc_assert (JUMP_LABEL (insn)); | |
| 320 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0); | |
| 321 } | |
| 322 } | |
| 323 | |
| 324 /* If this is a sibling call insn, then this is in effect a combined call | |
| 325 and return, and so we need an edge to the exit block. No need to | |
| 326 worry about EH edges, since we wouldn't have created the sibling call | |
| 327 in the first place. */ | |
| 328 if (code == CALL_INSN && SIBLING_CALL_P (insn)) | |
| 329 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR, | |
| 330 EDGE_SIBCALL | EDGE_ABNORMAL); | |
| 331 | |
| 332 /* If this is a CALL_INSN, then mark it as reaching the active EH | |
| 333 handler for this CALL_INSN. If we're handling non-call | |
| 334 exceptions then any insn can reach any of the active handlers. | |
| 335 Also mark the CALL_INSN as reaching any nonlocal goto handler. */ | |
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336 else if (code == CALL_INSN || cfun->can_throw_non_call_exceptions) |
| 0 | 337 { |
| 338 /* Add any appropriate EH edges. */ | |
| 339 rtl_make_eh_edge (edge_cache, bb, insn); | |
| 340 | |
| 341 if (code == CALL_INSN && nonlocal_goto_handler_labels) | |
| 342 { | |
| 343 /* ??? This could be made smarter: in some cases it's possible | |
| 344 to tell that certain calls will not do a nonlocal goto. | |
| 345 For example, if the nested functions that do the nonlocal | |
| 346 gotos do not have their addresses taken, then only calls to | |
| 347 those functions or to other nested functions that use them | |
| 348 could possibly do nonlocal gotos. */ | |
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349 if (can_nonlocal_goto (insn)) |
| 0 | 350 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1)) |
| 351 make_label_edge (edge_cache, bb, XEXP (x, 0), | |
| 352 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL); | |
| 353 } | |
| 354 } | |
| 355 | |
| 356 /* Find out if we can drop through to the next block. */ | |
| 357 insn = NEXT_INSN (insn); | |
| 358 e = find_edge (bb, EXIT_BLOCK_PTR); | |
| 359 if (e && e->flags & EDGE_FALLTHRU) | |
| 360 insn = NULL; | |
| 361 | |
| 362 while (insn | |
| 363 && NOTE_P (insn) | |
| 364 && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK) | |
| 365 insn = NEXT_INSN (insn); | |
| 366 | |
| 367 if (!insn) | |
| 368 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU); | |
| 369 else if (bb->next_bb != EXIT_BLOCK_PTR) | |
| 370 { | |
| 371 if (insn == BB_HEAD (bb->next_bb)) | |
| 372 cached_make_edge (edge_cache, bb, bb->next_bb, EDGE_FALLTHRU); | |
| 373 } | |
| 374 } | |
| 375 | |
| 376 if (edge_cache) | |
| 377 sbitmap_vector_free (edge_cache); | |
| 378 } | |
| 379 | |
| 380 static void | |
| 381 mark_tablejump_edge (rtx label) | |
| 382 { | |
| 383 basic_block bb; | |
| 384 | |
| 385 gcc_assert (LABEL_P (label)); | |
| 386 /* See comment in make_label_edge. */ | |
| 387 if (INSN_UID (label) == 0) | |
| 388 return; | |
| 389 bb = BLOCK_FOR_INSN (label); | |
| 390 SET_STATE (bb, FULL_STATE (bb) | BLOCK_USED_BY_TABLEJUMP); | |
| 391 } | |
| 392 | |
| 393 static void | |
| 394 purge_dead_tablejump_edges (basic_block bb, rtx table) | |
| 395 { | |
| 396 rtx insn = BB_END (bb), tmp; | |
| 397 rtvec vec; | |
| 398 int j; | |
| 399 edge_iterator ei; | |
| 400 edge e; | |
| 401 | |
| 402 if (GET_CODE (PATTERN (table)) == ADDR_VEC) | |
| 403 vec = XVEC (PATTERN (table), 0); | |
| 404 else | |
| 405 vec = XVEC (PATTERN (table), 1); | |
| 406 | |
| 407 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) | |
| 408 mark_tablejump_edge (XEXP (RTVEC_ELT (vec, j), 0)); | |
| 409 | |
| 410 /* Some targets (eg, ARM) emit a conditional jump that also | |
| 411 contains the out-of-range target. Scan for these and | |
| 412 add an edge if necessary. */ | |
| 413 if ((tmp = single_set (insn)) != NULL | |
| 414 && SET_DEST (tmp) == pc_rtx | |
| 415 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE | |
| 416 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF) | |
| 417 mark_tablejump_edge (XEXP (XEXP (SET_SRC (tmp), 2), 0)); | |
| 418 | |
| 419 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) | |
| 420 { | |
| 421 if (FULL_STATE (e->dest) & BLOCK_USED_BY_TABLEJUMP) | |
| 422 SET_STATE (e->dest, FULL_STATE (e->dest) | |
| 423 & ~(size_t) BLOCK_USED_BY_TABLEJUMP); | |
| 424 else if (!(e->flags & (EDGE_ABNORMAL | EDGE_EH))) | |
| 425 { | |
| 426 remove_edge (e); | |
| 427 continue; | |
| 428 } | |
| 429 ei_next (&ei); | |
| 430 } | |
| 431 } | |
| 432 | |
| 433 /* Scan basic block BB for possible BB boundaries inside the block | |
| 434 and create new basic blocks in the progress. */ | |
| 435 | |
| 436 static void | |
| 437 find_bb_boundaries (basic_block bb) | |
| 438 { | |
| 439 basic_block orig_bb = bb; | |
| 440 rtx insn = BB_HEAD (bb); | |
| 441 rtx end = BB_END (bb), x; | |
| 442 rtx table; | |
| 443 rtx flow_transfer_insn = NULL_RTX; | |
| 444 edge fallthru = NULL; | |
| 445 | |
| 446 if (insn == BB_END (bb)) | |
| 447 return; | |
| 448 | |
| 449 if (LABEL_P (insn)) | |
| 450 insn = NEXT_INSN (insn); | |
| 451 | |
| 452 /* Scan insn chain and try to find new basic block boundaries. */ | |
| 453 while (1) | |
| 454 { | |
| 455 enum rtx_code code = GET_CODE (insn); | |
| 456 | |
|
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457 /* In case we've previously seen an insn that effects a control |
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458 flow transfer, split the block. */ |
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459 if ((flow_transfer_insn || code == CODE_LABEL) |
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460 && inside_basic_block_p (insn)) |
| 0 | 461 { |
| 462 fallthru = split_block (bb, PREV_INSN (insn)); | |
| 463 if (flow_transfer_insn) | |
| 464 { | |
| 465 BB_END (bb) = flow_transfer_insn; | |
| 466 | |
| 467 /* Clean up the bb field for the insns between the blocks. */ | |
| 468 for (x = NEXT_INSN (flow_transfer_insn); | |
| 469 x != BB_HEAD (fallthru->dest); | |
| 470 x = NEXT_INSN (x)) | |
| 471 if (!BARRIER_P (x)) | |
| 472 set_block_for_insn (x, NULL); | |
| 473 } | |
| 474 | |
| 475 bb = fallthru->dest; | |
| 476 remove_edge (fallthru); | |
| 477 flow_transfer_insn = NULL_RTX; | |
|
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478 if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn)) |
| 0 | 479 make_edge (ENTRY_BLOCK_PTR, bb, 0); |
| 480 } | |
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481 else if (code == BARRIER) |
| 0 | 482 { |
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483 /* __builtin_unreachable () may cause a barrier to be emitted in |
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484 the middle of a BB. We need to split it in the same manner as |
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485 if the barrier were preceded by a control_flow_insn_p insn. */ |
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486 if (!flow_transfer_insn) |
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487 flow_transfer_insn = prev_nonnote_insn_bb (insn); |
| 0 | 488 } |
| 489 | |
| 490 if (control_flow_insn_p (insn)) | |
| 491 flow_transfer_insn = insn; | |
| 492 if (insn == end) | |
| 493 break; | |
| 494 insn = NEXT_INSN (insn); | |
| 495 } | |
| 496 | |
| 497 /* In case expander replaced normal insn by sequence terminating by | |
| 498 return and barrier, or possibly other sequence not behaving like | |
| 499 ordinary jump, we need to take care and move basic block boundary. */ | |
| 500 if (flow_transfer_insn) | |
| 501 { | |
| 502 BB_END (bb) = flow_transfer_insn; | |
| 503 | |
| 504 /* Clean up the bb field for the insns that do not belong to BB. */ | |
| 505 x = flow_transfer_insn; | |
| 506 while (x != end) | |
| 507 { | |
| 508 x = NEXT_INSN (x); | |
| 509 if (!BARRIER_P (x)) | |
| 510 set_block_for_insn (x, NULL); | |
| 511 } | |
| 512 } | |
| 513 | |
| 514 /* We've possibly replaced the conditional jump by conditional jump | |
| 515 followed by cleanup at fallthru edge, so the outgoing edges may | |
| 516 be dead. */ | |
| 517 purge_dead_edges (bb); | |
| 518 | |
| 519 /* purge_dead_edges doesn't handle tablejump's, but if we have split the | |
| 520 basic block, we might need to kill some edges. */ | |
| 521 if (bb != orig_bb && tablejump_p (BB_END (bb), NULL, &table)) | |
| 522 purge_dead_tablejump_edges (bb, table); | |
| 523 } | |
| 524 | |
| 525 /* Assume that frequency of basic block B is known. Compute frequencies | |
| 526 and probabilities of outgoing edges. */ | |
| 527 | |
| 528 static void | |
| 529 compute_outgoing_frequencies (basic_block b) | |
| 530 { | |
| 531 edge e, f; | |
| 532 edge_iterator ei; | |
| 533 | |
| 534 if (EDGE_COUNT (b->succs) == 2) | |
| 535 { | |
| 536 rtx note = find_reg_note (BB_END (b), REG_BR_PROB, NULL); | |
| 537 int probability; | |
| 538 | |
| 539 if (note) | |
| 540 { | |
| 541 probability = INTVAL (XEXP (note, 0)); | |
| 542 e = BRANCH_EDGE (b); | |
| 543 e->probability = probability; | |
| 544 e->count = ((b->count * probability + REG_BR_PROB_BASE / 2) | |
| 545 / REG_BR_PROB_BASE); | |
| 546 f = FALLTHRU_EDGE (b); | |
| 547 f->probability = REG_BR_PROB_BASE - probability; | |
| 548 f->count = b->count - e->count; | |
| 549 return; | |
| 550 } | |
| 551 } | |
| 552 | |
| 553 if (single_succ_p (b)) | |
| 554 { | |
| 555 e = single_succ_edge (b); | |
| 556 e->probability = REG_BR_PROB_BASE; | |
| 557 e->count = b->count; | |
| 558 return; | |
| 559 } | |
| 560 guess_outgoing_edge_probabilities (b); | |
| 561 if (b->count) | |
| 562 FOR_EACH_EDGE (e, ei, b->succs) | |
| 563 e->count = ((b->count * e->probability + REG_BR_PROB_BASE / 2) | |
| 564 / REG_BR_PROB_BASE); | |
| 565 } | |
| 566 | |
| 567 /* Assume that some pass has inserted labels or control flow | |
| 568 instructions within a basic block. Split basic blocks as needed | |
| 569 and create edges. */ | |
| 570 | |
| 571 void | |
| 572 find_many_sub_basic_blocks (sbitmap blocks) | |
| 573 { | |
| 574 basic_block bb, min, max; | |
| 575 | |
| 576 FOR_EACH_BB (bb) | |
| 577 SET_STATE (bb, | |
| 578 TEST_BIT (blocks, bb->index) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL); | |
| 579 | |
| 580 FOR_EACH_BB (bb) | |
| 581 if (STATE (bb) == BLOCK_TO_SPLIT) | |
| 582 find_bb_boundaries (bb); | |
| 583 | |
| 584 FOR_EACH_BB (bb) | |
| 585 if (STATE (bb) != BLOCK_ORIGINAL) | |
| 586 break; | |
| 587 | |
| 588 min = max = bb; | |
| 589 for (; bb != EXIT_BLOCK_PTR; bb = bb->next_bb) | |
| 590 if (STATE (bb) != BLOCK_ORIGINAL) | |
| 591 max = bb; | |
| 592 | |
| 593 /* Now re-scan and wire in all edges. This expect simple (conditional) | |
| 594 jumps at the end of each new basic blocks. */ | |
| 595 make_edges (min, max, 1); | |
| 596 | |
| 597 /* Update branch probabilities. Expect only (un)conditional jumps | |
| 598 to be created with only the forward edges. */ | |
| 599 if (profile_status != PROFILE_ABSENT) | |
| 600 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb) | |
| 601 { | |
| 602 edge e; | |
| 603 edge_iterator ei; | |
| 604 | |
| 605 if (STATE (bb) == BLOCK_ORIGINAL) | |
| 606 continue; | |
| 607 if (STATE (bb) == BLOCK_NEW) | |
| 608 { | |
| 609 bb->count = 0; | |
| 610 bb->frequency = 0; | |
| 611 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 612 { | |
| 613 bb->count += e->count; | |
| 614 bb->frequency += EDGE_FREQUENCY (e); | |
| 615 } | |
| 616 } | |
| 617 | |
| 618 compute_outgoing_frequencies (bb); | |
| 619 } | |
| 620 | |
| 621 FOR_EACH_BB (bb) | |
| 622 SET_STATE (bb, 0); | |
| 623 } |