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62b180e1 | 1 | /* SSA Jump Threading |
fbd26352 | 2 | Copyright (C) 2005-2019 Free Software Foundation, Inc. |
62b180e1 | 3 | Contributed by Jeff Law <law@redhat.com> |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
8c4c00c1 | 9 | the Free Software Foundation; either version 3, or (at your option) |
62b180e1 | 10 | any later version. |
11 | ||
12 | GCC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ | |
62b180e1 | 20 | |
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
9ef16211 | 24 | #include "backend.h" |
62b180e1 | 25 | #include "tree.h" |
9ef16211 | 26 | #include "gimple.h" |
7c29e30e | 27 | #include "predict.h" |
9ef16211 | 28 | #include "ssa.h" |
b20a8bb4 | 29 | #include "fold-const.h" |
94ea8568 | 30 | #include "cfgloop.h" |
dcf1a1ec | 31 | #include "gimple-iterator.h" |
073c1fd5 | 32 | #include "tree-cfg.h" |
0c5b289a | 33 | #include "tree-ssa-threadupdate.h" |
62b180e1 | 34 | #include "params.h" |
545372c5 | 35 | #include "tree-ssa-scopedtables.h" |
424a4a92 | 36 | #include "tree-ssa-threadedge.h" |
9f4680b7 | 37 | #include "tree-ssa-dom.h" |
1603b4dc | 38 | #include "gimple-fold.h" |
2abf3c4a | 39 | #include "cfganal.h" |
4b69806c | 40 | #include "alloc-pool.h" |
41 | #include "vr-values.h" | |
42 | #include "gimple-ssa-evrp-analyze.h" | |
62b180e1 | 43 | |
44 | /* To avoid code explosion due to jump threading, we limit the | |
45 | number of statements we are going to copy. This variable | |
46 | holds the number of statements currently seen that we'll have | |
47 | to copy as part of the jump threading process. */ | |
48 | static int stmt_count; | |
49 | ||
f003f9fd | 50 | /* Array to record value-handles per SSA_NAME. */ |
f1f41a6c | 51 | vec<tree> ssa_name_values; |
f003f9fd | 52 | |
be244ef5 | 53 | typedef tree (pfn_simplify) (gimple *, gimple *, |
54 | class avail_exprs_stack *, | |
55 | basic_block); | |
a8a97533 | 56 | |
f003f9fd | 57 | /* Set the value for the SSA name NAME to VALUE. */ |
58 | ||
59 | void | |
60 | set_ssa_name_value (tree name, tree value) | |
61 | { | |
f1f41a6c | 62 | if (SSA_NAME_VERSION (name) >= ssa_name_values.length ()) |
63 | ssa_name_values.safe_grow_cleared (SSA_NAME_VERSION (name) + 1); | |
f5faab84 | 64 | if (value && TREE_OVERFLOW_P (value)) |
65 | value = drop_tree_overflow (value); | |
f1f41a6c | 66 | ssa_name_values[SSA_NAME_VERSION (name)] = value; |
f003f9fd | 67 | } |
68 | ||
69 | /* Initialize the per SSA_NAME value-handles array. Returns it. */ | |
70 | void | |
71 | threadedge_initialize_values (void) | |
72 | { | |
f1f41a6c | 73 | gcc_assert (!ssa_name_values.exists ()); |
74 | ssa_name_values.create (num_ssa_names); | |
f003f9fd | 75 | } |
76 | ||
77 | /* Free the per SSA_NAME value-handle array. */ | |
78 | void | |
79 | threadedge_finalize_values (void) | |
80 | { | |
f1f41a6c | 81 | ssa_name_values.release (); |
f003f9fd | 82 | } |
83 | ||
62b180e1 | 84 | /* Return TRUE if we may be able to thread an incoming edge into |
85 | BB to an outgoing edge from BB. Return FALSE otherwise. */ | |
86 | ||
87 | bool | |
88 | potentially_threadable_block (basic_block bb) | |
89 | { | |
75a70cf9 | 90 | gimple_stmt_iterator gsi; |
62b180e1 | 91 | |
849b1089 | 92 | /* Special case. We can get blocks that are forwarders, but are |
93 | not optimized away because they forward from outside a loop | |
94 | to the loop header. We want to thread through them as we can | |
1c71d7c1 | 95 | sometimes thread to the loop exit, which is obviously profitable. |
849b1089 | 96 | the interesting case here is when the block has PHIs. */ |
97 | if (gsi_end_p (gsi_start_nondebug_bb (bb)) | |
98 | && !gsi_end_p (gsi_start_phis (bb))) | |
99 | return true; | |
1c71d7c1 | 100 | |
62b180e1 | 101 | /* If BB has a single successor or a single predecessor, then |
102 | there is no threading opportunity. */ | |
103 | if (single_succ_p (bb) || single_pred_p (bb)) | |
104 | return false; | |
105 | ||
106 | /* If BB does not end with a conditional, switch or computed goto, | |
107 | then there is no threading opportunity. */ | |
75a70cf9 | 108 | gsi = gsi_last_bb (bb); |
109 | if (gsi_end_p (gsi) | |
110 | || ! gsi_stmt (gsi) | |
111 | || (gimple_code (gsi_stmt (gsi)) != GIMPLE_COND | |
112 | && gimple_code (gsi_stmt (gsi)) != GIMPLE_GOTO | |
113 | && gimple_code (gsi_stmt (gsi)) != GIMPLE_SWITCH)) | |
62b180e1 | 114 | return false; |
115 | ||
116 | return true; | |
117 | } | |
118 | ||
62b180e1 | 119 | /* Record temporary equivalences created by PHIs at the target of the |
4b69806c | 120 | edge E. Record unwind information for the equivalences into |
121 | CONST_AND_COPIES and EVRP_RANGE_DATA. | |
62b180e1 | 122 | |
123 | If a PHI which prevents threading is encountered, then return FALSE | |
4b69806c | 124 | indicating we should not thread this edge, else return TRUE. */ |
62b180e1 | 125 | |
126 | static bool | |
4b69806c | 127 | record_temporary_equivalences_from_phis (edge e, |
128 | const_and_copies *const_and_copies, | |
129 | evrp_range_analyzer *evrp_range_analyzer) | |
62b180e1 | 130 | { |
1a91d914 | 131 | gphi_iterator gsi; |
62b180e1 | 132 | |
133 | /* Each PHI creates a temporary equivalence, record them. | |
134 | These are context sensitive equivalences and will be removed | |
135 | later. */ | |
75a70cf9 | 136 | for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) |
62b180e1 | 137 | { |
1a91d914 | 138 | gphi *phi = gsi.phi (); |
62b180e1 | 139 | tree src = PHI_ARG_DEF_FROM_EDGE (phi, e); |
75a70cf9 | 140 | tree dst = gimple_phi_result (phi); |
62b180e1 | 141 | |
48e1416a | 142 | /* If the desired argument is not the same as this PHI's result |
f4d3c071 | 143 | and it is set by a PHI in E->dest, then we cannot thread |
62b180e1 | 144 | through E->dest. */ |
145 | if (src != dst | |
146 | && TREE_CODE (src) == SSA_NAME | |
75a70cf9 | 147 | && gimple_code (SSA_NAME_DEF_STMT (src)) == GIMPLE_PHI |
148 | && gimple_bb (SSA_NAME_DEF_STMT (src)) == e->dest) | |
62b180e1 | 149 | return false; |
150 | ||
151 | /* We consider any non-virtual PHI as a statement since it | |
152 | count result in a constant assignment or copy operation. */ | |
7c782c9b | 153 | if (!virtual_operand_p (dst)) |
62b180e1 | 154 | stmt_count++; |
155 | ||
545372c5 | 156 | const_and_copies->record_const_or_copy (dst, src); |
4b69806c | 157 | |
158 | /* Also update the value range associated with DST, using | |
2638400f | 159 | the range from SRC. |
160 | ||
161 | Note that even if SRC is a constant we need to set a suitable | |
162 | output range so that VR_UNDEFINED ranges do not leak through. */ | |
163 | if (evrp_range_analyzer) | |
4b69806c | 164 | { |
2638400f | 165 | /* Get an empty new VR we can pass to update_value_range and save |
166 | away in the VR stack. */ | |
167 | vr_values *vr_values = evrp_range_analyzer->get_vr_values (); | |
168 | value_range *new_vr = vr_values->allocate_value_range (); | |
48625f58 | 169 | new (new_vr) value_range (); |
2638400f | 170 | |
171 | /* There are three cases to consider: | |
172 | ||
173 | First if SRC is an SSA_NAME, then we can copy the value | |
174 | range from SRC into NEW_VR. | |
175 | ||
176 | Second if SRC is an INTEGER_CST, then we can just wet | |
177 | NEW_VR to a singleton range. | |
178 | ||
179 | Otherwise set NEW_VR to varying. This may be overly | |
180 | conservative. */ | |
181 | if (TREE_CODE (src) == SSA_NAME) | |
be44111e | 182 | new_vr->deep_copy (vr_values->get_value_range (src)); |
2638400f | 183 | else if (TREE_CODE (src) == INTEGER_CST) |
48625f58 | 184 | new_vr->set (src); |
2638400f | 185 | else |
d8f890de | 186 | new_vr->set_varying (TREE_TYPE (src)); |
2638400f | 187 | |
188 | /* This is a temporary range for DST, so push it. */ | |
189 | evrp_range_analyzer->push_value_range (dst, new_vr); | |
4b69806c | 190 | } |
62b180e1 | 191 | } |
192 | return true; | |
193 | } | |
194 | ||
1603b4dc | 195 | /* Valueize hook for gimple_fold_stmt_to_constant_1. */ |
75a70cf9 | 196 | |
197 | static tree | |
1603b4dc | 198 | threadedge_valueize (tree t) |
75a70cf9 | 199 | { |
1603b4dc | 200 | if (TREE_CODE (t) == SSA_NAME) |
75a70cf9 | 201 | { |
1603b4dc | 202 | tree tem = SSA_NAME_VALUE (t); |
203 | if (tem) | |
204 | return tem; | |
75a70cf9 | 205 | } |
1603b4dc | 206 | return t; |
75a70cf9 | 207 | } |
208 | ||
62b180e1 | 209 | /* Try to simplify each statement in E->dest, ultimately leading to |
210 | a simplification of the COND_EXPR at the end of E->dest. | |
211 | ||
212 | Record unwind information for temporary equivalences onto STACK. | |
213 | ||
214 | Use SIMPLIFY (a pointer to a callback function) to further simplify | |
48e1416a | 215 | statements using pass specific information. |
62b180e1 | 216 | |
217 | We might consider marking just those statements which ultimately | |
218 | feed the COND_EXPR. It's not clear if the overhead of bookkeeping | |
219 | would be recovered by trying to simplify fewer statements. | |
220 | ||
221 | If we are able to simplify a statement into the form | |
222 | SSA_NAME = (SSA_NAME | gimple invariant), then we can record | |
75a70cf9 | 223 | a context sensitive equivalence which may help us simplify |
62b180e1 | 224 | later statements in E->dest. */ |
225 | ||
42acab1c | 226 | static gimple * |
62b180e1 | 227 | record_temporary_equivalences_from_stmts_at_dest (edge e, |
a8a97533 | 228 | const_and_copies *const_and_copies, |
229 | avail_exprs_stack *avail_exprs_stack, | |
4b69806c | 230 | evrp_range_analyzer *evrp_range_analyzer, |
694a1a82 | 231 | pfn_simplify simplify) |
62b180e1 | 232 | { |
42acab1c | 233 | gimple *stmt = NULL; |
75a70cf9 | 234 | gimple_stmt_iterator gsi; |
62b180e1 | 235 | int max_stmt_count; |
236 | ||
237 | max_stmt_count = PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS); | |
238 | ||
239 | /* Walk through each statement in the block recording equivalences | |
240 | we discover. Note any equivalences we discover are context | |
241 | sensitive (ie, are dependent on traversing E) and must be unwound | |
242 | when we're finished processing E. */ | |
75a70cf9 | 243 | for (gsi = gsi_start_bb (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) |
62b180e1 | 244 | { |
245 | tree cached_lhs = NULL; | |
246 | ||
75a70cf9 | 247 | stmt = gsi_stmt (gsi); |
62b180e1 | 248 | |
249 | /* Ignore empty statements and labels. */ | |
9845d120 | 250 | if (gimple_code (stmt) == GIMPLE_NOP |
251 | || gimple_code (stmt) == GIMPLE_LABEL | |
252 | || is_gimple_debug (stmt)) | |
62b180e1 | 253 | continue; |
254 | ||
62b180e1 | 255 | /* If the statement has volatile operands, then we assume we |
f4d3c071 | 256 | cannot thread through this block. This is overly |
62b180e1 | 257 | conservative in some ways. */ |
1a91d914 | 258 | if (gimple_code (stmt) == GIMPLE_ASM |
259 | && gimple_asm_volatile_p (as_a <gasm *> (stmt))) | |
62b180e1 | 260 | return NULL; |
261 | ||
f4d3c071 | 262 | /* If the statement is a unique builtin, we cannot thread |
6c5c88f6 | 263 | through here. */ |
264 | if (gimple_code (stmt) == GIMPLE_CALL | |
265 | && gimple_call_internal_p (stmt) | |
266 | && gimple_call_internal_unique_p (stmt)) | |
267 | return NULL; | |
268 | ||
62b180e1 | 269 | /* If duplicating this block is going to cause too much code |
270 | expansion, then do not thread through this block. */ | |
271 | stmt_count++; | |
272 | if (stmt_count > max_stmt_count) | |
a8855004 | 273 | { |
274 | /* If any of the stmts in the PATH's dests are going to be | |
275 | killed due to threading, grow the max count | |
276 | accordingly. */ | |
277 | if (max_stmt_count | |
278 | == PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS)) | |
279 | { | |
280 | max_stmt_count += estimate_threading_killed_stmts (e->dest); | |
281 | if (dump_file) | |
282 | fprintf (dump_file, "threading bb %i up to %i stmts\n", | |
283 | e->dest->index, max_stmt_count); | |
284 | } | |
285 | /* If we're still past the limit, we're done. */ | |
286 | if (stmt_count > max_stmt_count) | |
287 | return NULL; | |
288 | } | |
62b180e1 | 289 | |
4b69806c | 290 | /* These are temporary ranges, do nto reflect them back into |
291 | the global range data. */ | |
292 | if (evrp_range_analyzer) | |
293 | evrp_range_analyzer->record_ranges_from_stmt (stmt, true); | |
294 | ||
75a70cf9 | 295 | /* If this is not a statement that sets an SSA_NAME to a new |
62b180e1 | 296 | value, then do not try to simplify this statement as it will |
297 | not simplify in any way that is helpful for jump threading. */ | |
75a70cf9 | 298 | if ((gimple_code (stmt) != GIMPLE_ASSIGN |
299 | || TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME) | |
300 | && (gimple_code (stmt) != GIMPLE_CALL | |
301 | || gimple_call_lhs (stmt) == NULL_TREE | |
302 | || TREE_CODE (gimple_call_lhs (stmt)) != SSA_NAME)) | |
694a1a82 | 303 | continue; |
62b180e1 | 304 | |
55c10931 | 305 | /* The result of __builtin_object_size depends on all the arguments |
306 | of a phi node. Temporarily using only one edge produces invalid | |
307 | results. For example | |
308 | ||
309 | if (x < 6) | |
310 | goto l; | |
311 | else | |
312 | goto l; | |
313 | ||
314 | l: | |
315 | r = PHI <&w[2].a[1](2), &a.a[6](3)> | |
316 | __builtin_object_size (r, 0) | |
317 | ||
318 | The result of __builtin_object_size is defined to be the maximum of | |
319 | remaining bytes. If we use only one edge on the phi, the result will | |
99e2edfd | 320 | change to be the remaining bytes for the corresponding phi argument. |
321 | ||
322 | Similarly for __builtin_constant_p: | |
323 | ||
324 | r = PHI <1(2), 2(3)> | |
325 | __builtin_constant_p (r) | |
326 | ||
327 | Both PHI arguments are constant, but x ? 1 : 2 is still not | |
328 | constant. */ | |
55c10931 | 329 | |
75a70cf9 | 330 | if (is_gimple_call (stmt)) |
55c10931 | 331 | { |
75a70cf9 | 332 | tree fndecl = gimple_call_fndecl (stmt); |
99e2edfd | 333 | if (fndecl |
50b8400c | 334 | && fndecl_built_in_p (fndecl, BUILT_IN_NORMAL) |
99e2edfd | 335 | && (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_OBJECT_SIZE |
336 | || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P)) | |
694a1a82 | 337 | continue; |
55c10931 | 338 | } |
339 | ||
62b180e1 | 340 | /* At this point we have a statement which assigns an RHS to an |
341 | SSA_VAR on the LHS. We want to try and simplify this statement | |
342 | to expose more context sensitive equivalences which in turn may | |
48e1416a | 343 | allow us to simplify the condition at the end of the loop. |
62b180e1 | 344 | |
345 | Handle simple copy operations as well as implied copies from | |
346 | ASSERT_EXPRs. */ | |
75a70cf9 | 347 | if (gimple_assign_single_p (stmt) |
348 | && TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME) | |
349 | cached_lhs = gimple_assign_rhs1 (stmt); | |
350 | else if (gimple_assign_single_p (stmt) | |
351 | && TREE_CODE (gimple_assign_rhs1 (stmt)) == ASSERT_EXPR) | |
352 | cached_lhs = TREE_OPERAND (gimple_assign_rhs1 (stmt), 0); | |
62b180e1 | 353 | else |
354 | { | |
355 | /* A statement that is not a trivial copy or ASSERT_EXPR. | |
1603b4dc | 356 | Try to fold the new expression. Inserting the |
75a70cf9 | 357 | expression into the hash table is unlikely to help. */ |
1603b4dc | 358 | /* ??? The DOM callback below can be changed to setting |
359 | the mprts_hook around the call to thread_across_edge, | |
360 | avoiding the use substitution. The VRP hook should be | |
361 | changed to properly valueize operands itself using | |
362 | SSA_NAME_VALUE in addition to its own lattice. */ | |
363 | cached_lhs = gimple_fold_stmt_to_constant_1 (stmt, | |
364 | threadedge_valueize); | |
fc7572a0 | 365 | if (NUM_SSA_OPERANDS (stmt, SSA_OP_ALL_USES) != 0 |
366 | && (!cached_lhs | |
367 | || (TREE_CODE (cached_lhs) != SSA_NAME | |
368 | && !is_gimple_min_invariant (cached_lhs)))) | |
1603b4dc | 369 | { |
370 | /* We're going to temporarily copy propagate the operands | |
371 | and see if that allows us to simplify this statement. */ | |
372 | tree *copy; | |
373 | ssa_op_iter iter; | |
374 | use_operand_p use_p; | |
375 | unsigned int num, i = 0; | |
376 | ||
377 | num = NUM_SSA_OPERANDS (stmt, SSA_OP_ALL_USES); | |
378 | copy = XALLOCAVEC (tree, num); | |
379 | ||
380 | /* Make a copy of the uses & vuses into USES_COPY, then cprop into | |
381 | the operands. */ | |
382 | FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES) | |
383 | { | |
384 | tree tmp = NULL; | |
385 | tree use = USE_FROM_PTR (use_p); | |
386 | ||
387 | copy[i++] = use; | |
388 | if (TREE_CODE (use) == SSA_NAME) | |
389 | tmp = SSA_NAME_VALUE (use); | |
390 | if (tmp) | |
391 | SET_USE (use_p, tmp); | |
392 | } | |
48e1416a | 393 | |
be244ef5 | 394 | cached_lhs = (*simplify) (stmt, stmt, avail_exprs_stack, e->src); |
62b180e1 | 395 | |
1603b4dc | 396 | /* Restore the statement's original uses/defs. */ |
397 | i = 0; | |
398 | FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES) | |
399 | SET_USE (use_p, copy[i++]); | |
400 | } | |
62b180e1 | 401 | } |
402 | ||
403 | /* Record the context sensitive equivalence if we were able | |
694a1a82 | 404 | to simplify this statement. */ |
62b180e1 | 405 | if (cached_lhs |
406 | && (TREE_CODE (cached_lhs) == SSA_NAME | |
407 | || is_gimple_min_invariant (cached_lhs))) | |
9964a983 | 408 | const_and_copies->record_const_or_copy (gimple_get_lhs (stmt), |
409 | cached_lhs); | |
62b180e1 | 410 | } |
411 | return stmt; | |
412 | } | |
413 | ||
46f37836 | 414 | static tree simplify_control_stmt_condition_1 (edge, gimple *, |
415 | class avail_exprs_stack *, | |
416 | tree, enum tree_code, tree, | |
be244ef5 | 417 | gcond *, pfn_simplify, |
46f37836 | 418 | unsigned); |
419 | ||
62b180e1 | 420 | /* Simplify the control statement at the end of the block E->dest. |
421 | ||
75a70cf9 | 422 | To avoid allocating memory unnecessarily, a scratch GIMPLE_COND |
62b180e1 | 423 | is available to use/clobber in DUMMY_COND. |
424 | ||
425 | Use SIMPLIFY (a pointer to a callback function) to further simplify | |
426 | a condition using pass specific information. | |
427 | ||
428 | Return the simplified condition or NULL if simplification could | |
2abf3c4a | 429 | not be performed. When simplifying a GIMPLE_SWITCH, we may return |
430 | the CASE_LABEL_EXPR that will be taken. | |
a8a97533 | 431 | |
432 | The available expression table is referenced via AVAIL_EXPRS_STACK. */ | |
62b180e1 | 433 | |
434 | static tree | |
435 | simplify_control_stmt_condition (edge e, | |
42acab1c | 436 | gimple *stmt, |
a8a97533 | 437 | class avail_exprs_stack *avail_exprs_stack, |
1a91d914 | 438 | gcond *dummy_cond, |
be244ef5 | 439 | pfn_simplify simplify) |
62b180e1 | 440 | { |
441 | tree cond, cached_lhs; | |
75a70cf9 | 442 | enum gimple_code code = gimple_code (stmt); |
62b180e1 | 443 | |
444 | /* For comparisons, we have to update both operands, then try | |
445 | to simplify the comparison. */ | |
75a70cf9 | 446 | if (code == GIMPLE_COND) |
62b180e1 | 447 | { |
448 | tree op0, op1; | |
449 | enum tree_code cond_code; | |
450 | ||
75a70cf9 | 451 | op0 = gimple_cond_lhs (stmt); |
452 | op1 = gimple_cond_rhs (stmt); | |
453 | cond_code = gimple_cond_code (stmt); | |
62b180e1 | 454 | |
455 | /* Get the current value of both operands. */ | |
456 | if (TREE_CODE (op0) == SSA_NAME) | |
457 | { | |
1cda6e06 | 458 | for (int i = 0; i < 2; i++) |
459 | { | |
460 | if (TREE_CODE (op0) == SSA_NAME | |
461 | && SSA_NAME_VALUE (op0)) | |
462 | op0 = SSA_NAME_VALUE (op0); | |
463 | else | |
464 | break; | |
465 | } | |
62b180e1 | 466 | } |
467 | ||
468 | if (TREE_CODE (op1) == SSA_NAME) | |
469 | { | |
1cda6e06 | 470 | for (int i = 0; i < 2; i++) |
471 | { | |
472 | if (TREE_CODE (op1) == SSA_NAME | |
473 | && SSA_NAME_VALUE (op1)) | |
474 | op1 = SSA_NAME_VALUE (op1); | |
475 | else | |
476 | break; | |
477 | } | |
62b180e1 | 478 | } |
479 | ||
46f37836 | 480 | const unsigned recursion_limit = 4; |
62b180e1 | 481 | |
46f37836 | 482 | cached_lhs |
483 | = simplify_control_stmt_condition_1 (e, stmt, avail_exprs_stack, | |
484 | op0, cond_code, op1, | |
485 | dummy_cond, simplify, | |
46f37836 | 486 | recursion_limit); |
75a70cf9 | 487 | |
f08943b6 | 488 | /* If we were testing an integer/pointer against a constant, then |
489 | we can use the FSM code to trace the value of the SSA_NAME. If | |
490 | a value is found, then the condition will collapse to a constant. | |
491 | ||
492 | Return the SSA_NAME we want to trace back rather than the full | |
493 | expression and give the FSM threader a chance to find its value. */ | |
494 | if (cached_lhs == NULL) | |
7729459f | 495 | { |
496 | /* Recover the original operands. They may have been simplified | |
497 | using context sensitive equivalences. Those context sensitive | |
498 | equivalences may not be valid on paths found by the FSM optimizer. */ | |
499 | tree op0 = gimple_cond_lhs (stmt); | |
500 | tree op1 = gimple_cond_rhs (stmt); | |
501 | ||
f08943b6 | 502 | if ((INTEGRAL_TYPE_P (TREE_TYPE (op0)) |
503 | || POINTER_TYPE_P (TREE_TYPE (op0))) | |
7729459f | 504 | && TREE_CODE (op0) == SSA_NAME |
f08943b6 | 505 | && TREE_CODE (op1) == INTEGER_CST) |
7729459f | 506 | return op0; |
507 | } | |
508 | ||
75a70cf9 | 509 | return cached_lhs; |
62b180e1 | 510 | } |
511 | ||
75a70cf9 | 512 | if (code == GIMPLE_SWITCH) |
1a91d914 | 513 | cond = gimple_switch_index (as_a <gswitch *> (stmt)); |
75a70cf9 | 514 | else if (code == GIMPLE_GOTO) |
515 | cond = gimple_goto_dest (stmt); | |
516 | else | |
517 | gcc_unreachable (); | |
518 | ||
62b180e1 | 519 | /* We can have conditionals which just test the state of a variable |
520 | rather than use a relational operator. These are simpler to handle. */ | |
75a70cf9 | 521 | if (TREE_CODE (cond) == SSA_NAME) |
62b180e1 | 522 | { |
ded1c768 | 523 | tree original_lhs = cond; |
62b180e1 | 524 | cached_lhs = cond; |
525 | ||
75a70cf9 | 526 | /* Get the variable's current value from the equivalence chains. |
2a5af6bf | 527 | |
528 | It is possible to get loops in the SSA_NAME_VALUE chains | |
529 | (consider threading the backedge of a loop where we have | |
580efa23 | 530 | a loop invariant SSA_NAME used in the condition). */ |
1cda6e06 | 531 | if (cached_lhs) |
532 | { | |
533 | for (int i = 0; i < 2; i++) | |
534 | { | |
535 | if (TREE_CODE (cached_lhs) == SSA_NAME | |
536 | && SSA_NAME_VALUE (cached_lhs)) | |
537 | cached_lhs = SSA_NAME_VALUE (cached_lhs); | |
538 | else | |
539 | break; | |
540 | } | |
541 | } | |
62b180e1 | 542 | |
62b180e1 | 543 | /* If we haven't simplified to an invariant yet, then use the |
544 | pass specific callback to try and simplify it further. */ | |
545 | if (cached_lhs && ! is_gimple_min_invariant (cached_lhs)) | |
2abf3c4a | 546 | { |
be244ef5 | 547 | if (code == GIMPLE_SWITCH) |
2abf3c4a | 548 | { |
be244ef5 | 549 | /* Replace the index operand of the GIMPLE_SWITCH with any LHS |
550 | we found before handing off to VRP. If simplification is | |
551 | possible, the simplified value will be a CASE_LABEL_EXPR of | |
552 | the label that is proven to be taken. */ | |
2abf3c4a | 553 | gswitch *dummy_switch = as_a<gswitch *> (gimple_copy (stmt)); |
554 | gimple_switch_set_index (dummy_switch, cached_lhs); | |
be244ef5 | 555 | cached_lhs = (*simplify) (dummy_switch, stmt, |
556 | avail_exprs_stack, e->src); | |
2abf3c4a | 557 | ggc_free (dummy_switch); |
558 | } | |
559 | else | |
be244ef5 | 560 | cached_lhs = (*simplify) (stmt, stmt, avail_exprs_stack, e->src); |
2abf3c4a | 561 | } |
ded1c768 | 562 | |
563 | /* We couldn't find an invariant. But, callers of this | |
564 | function may be able to do something useful with the | |
565 | unmodified destination. */ | |
566 | if (!cached_lhs) | |
567 | cached_lhs = original_lhs; | |
62b180e1 | 568 | } |
569 | else | |
570 | cached_lhs = NULL; | |
571 | ||
572 | return cached_lhs; | |
573 | } | |
574 | ||
46f37836 | 575 | /* Recursive helper for simplify_control_stmt_condition. */ |
576 | ||
577 | static tree | |
578 | simplify_control_stmt_condition_1 (edge e, | |
579 | gimple *stmt, | |
580 | class avail_exprs_stack *avail_exprs_stack, | |
581 | tree op0, | |
582 | enum tree_code cond_code, | |
583 | tree op1, | |
584 | gcond *dummy_cond, | |
585 | pfn_simplify simplify, | |
46f37836 | 586 | unsigned limit) |
587 | { | |
588 | if (limit == 0) | |
589 | return NULL_TREE; | |
590 | ||
591 | /* We may need to canonicalize the comparison. For | |
592 | example, op0 might be a constant while op1 is an | |
593 | SSA_NAME. Failure to canonicalize will cause us to | |
594 | miss threading opportunities. */ | |
48baf518 | 595 | if (tree_swap_operands_p (op0, op1)) |
46f37836 | 596 | { |
597 | cond_code = swap_tree_comparison (cond_code); | |
598 | std::swap (op0, op1); | |
599 | } | |
600 | ||
601 | /* If the condition has the form (A & B) CMP 0 or (A | B) CMP 0 then | |
602 | recurse into the LHS to see if there is a dominating ASSERT_EXPR | |
603 | of A or of B that makes this condition always true or always false | |
604 | along the edge E. */ | |
be244ef5 | 605 | if ((cond_code == EQ_EXPR || cond_code == NE_EXPR) |
46f37836 | 606 | && TREE_CODE (op0) == SSA_NAME |
607 | && integer_zerop (op1)) | |
608 | { | |
609 | gimple *def_stmt = SSA_NAME_DEF_STMT (op0); | |
610 | if (gimple_code (def_stmt) != GIMPLE_ASSIGN) | |
611 | ; | |
612 | else if (gimple_assign_rhs_code (def_stmt) == BIT_AND_EXPR | |
613 | || gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR) | |
614 | { | |
615 | enum tree_code rhs_code = gimple_assign_rhs_code (def_stmt); | |
616 | const tree rhs1 = gimple_assign_rhs1 (def_stmt); | |
617 | const tree rhs2 = gimple_assign_rhs2 (def_stmt); | |
46f37836 | 618 | |
619 | /* Is A != 0 ? */ | |
620 | const tree res1 | |
621 | = simplify_control_stmt_condition_1 (e, def_stmt, avail_exprs_stack, | |
622 | rhs1, NE_EXPR, op1, | |
623 | dummy_cond, simplify, | |
46f37836 | 624 | limit - 1); |
625 | if (res1 == NULL_TREE) | |
626 | ; | |
627 | else if (rhs_code == BIT_AND_EXPR && integer_zerop (res1)) | |
628 | { | |
629 | /* If A == 0 then (A & B) != 0 is always false. */ | |
630 | if (cond_code == NE_EXPR) | |
31e02373 | 631 | return boolean_false_node; |
46f37836 | 632 | /* If A == 0 then (A & B) == 0 is always true. */ |
633 | if (cond_code == EQ_EXPR) | |
31e02373 | 634 | return boolean_true_node; |
46f37836 | 635 | } |
636 | else if (rhs_code == BIT_IOR_EXPR && integer_nonzerop (res1)) | |
637 | { | |
638 | /* If A != 0 then (A | B) != 0 is always true. */ | |
639 | if (cond_code == NE_EXPR) | |
31e02373 | 640 | return boolean_true_node; |
46f37836 | 641 | /* If A != 0 then (A | B) == 0 is always false. */ |
642 | if (cond_code == EQ_EXPR) | |
31e02373 | 643 | return boolean_false_node; |
46f37836 | 644 | } |
645 | ||
646 | /* Is B != 0 ? */ | |
647 | const tree res2 | |
648 | = simplify_control_stmt_condition_1 (e, def_stmt, avail_exprs_stack, | |
649 | rhs2, NE_EXPR, op1, | |
650 | dummy_cond, simplify, | |
46f37836 | 651 | limit - 1); |
652 | if (res2 == NULL_TREE) | |
653 | ; | |
654 | else if (rhs_code == BIT_AND_EXPR && integer_zerop (res2)) | |
655 | { | |
656 | /* If B == 0 then (A & B) != 0 is always false. */ | |
657 | if (cond_code == NE_EXPR) | |
31e02373 | 658 | return boolean_false_node; |
46f37836 | 659 | /* If B == 0 then (A & B) == 0 is always true. */ |
660 | if (cond_code == EQ_EXPR) | |
31e02373 | 661 | return boolean_true_node; |
46f37836 | 662 | } |
663 | else if (rhs_code == BIT_IOR_EXPR && integer_nonzerop (res2)) | |
664 | { | |
665 | /* If B != 0 then (A | B) != 0 is always true. */ | |
666 | if (cond_code == NE_EXPR) | |
31e02373 | 667 | return boolean_true_node; |
46f37836 | 668 | /* If B != 0 then (A | B) == 0 is always false. */ |
669 | if (cond_code == EQ_EXPR) | |
31e02373 | 670 | return boolean_false_node; |
46f37836 | 671 | } |
672 | ||
673 | if (res1 != NULL_TREE && res2 != NULL_TREE) | |
674 | { | |
675 | if (rhs_code == BIT_AND_EXPR | |
676 | && TYPE_PRECISION (TREE_TYPE (op0)) == 1 | |
677 | && integer_nonzerop (res1) | |
678 | && integer_nonzerop (res2)) | |
679 | { | |
680 | /* If A != 0 and B != 0 then (bool)(A & B) != 0 is true. */ | |
681 | if (cond_code == NE_EXPR) | |
31e02373 | 682 | return boolean_true_node; |
46f37836 | 683 | /* If A != 0 and B != 0 then (bool)(A & B) == 0 is false. */ |
684 | if (cond_code == EQ_EXPR) | |
31e02373 | 685 | return boolean_false_node; |
46f37836 | 686 | } |
687 | ||
688 | if (rhs_code == BIT_IOR_EXPR | |
689 | && integer_zerop (res1) | |
690 | && integer_zerop (res2)) | |
691 | { | |
692 | /* If A == 0 and B == 0 then (A | B) != 0 is false. */ | |
693 | if (cond_code == NE_EXPR) | |
31e02373 | 694 | return boolean_false_node; |
46f37836 | 695 | /* If A == 0 and B == 0 then (A | B) == 0 is true. */ |
696 | if (cond_code == EQ_EXPR) | |
31e02373 | 697 | return boolean_true_node; |
46f37836 | 698 | } |
699 | } | |
700 | } | |
701 | /* Handle (A CMP B) CMP 0. */ | |
702 | else if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) | |
703 | == tcc_comparison) | |
704 | { | |
705 | tree rhs1 = gimple_assign_rhs1 (def_stmt); | |
706 | tree rhs2 = gimple_assign_rhs2 (def_stmt); | |
707 | ||
708 | tree_code new_cond = gimple_assign_rhs_code (def_stmt); | |
709 | if (cond_code == EQ_EXPR) | |
710 | new_cond = invert_tree_comparison (new_cond, false); | |
711 | ||
712 | tree res | |
713 | = simplify_control_stmt_condition_1 (e, def_stmt, avail_exprs_stack, | |
714 | rhs1, new_cond, rhs2, | |
715 | dummy_cond, simplify, | |
46f37836 | 716 | limit - 1); |
717 | if (res != NULL_TREE && is_gimple_min_invariant (res)) | |
718 | return res; | |
719 | } | |
720 | } | |
721 | ||
46f37836 | 722 | gimple_cond_set_code (dummy_cond, cond_code); |
723 | gimple_cond_set_lhs (dummy_cond, op0); | |
724 | gimple_cond_set_rhs (dummy_cond, op1); | |
725 | ||
726 | /* We absolutely do not care about any type conversions | |
727 | we only care about a zero/nonzero value. */ | |
728 | fold_defer_overflow_warnings (); | |
729 | ||
730 | tree res = fold_binary (cond_code, boolean_type_node, op0, op1); | |
731 | if (res) | |
732 | while (CONVERT_EXPR_P (res)) | |
733 | res = TREE_OPERAND (res, 0); | |
734 | ||
735 | fold_undefer_overflow_warnings ((res && is_gimple_min_invariant (res)), | |
736 | stmt, WARN_STRICT_OVERFLOW_CONDITIONAL); | |
737 | ||
738 | /* If we have not simplified the condition down to an invariant, | |
739 | then use the pass specific callback to simplify the condition. */ | |
740 | if (!res | |
741 | || !is_gimple_min_invariant (res)) | |
be244ef5 | 742 | res = (*simplify) (dummy_cond, stmt, avail_exprs_stack, e->src); |
46f37836 | 743 | |
744 | return res; | |
745 | } | |
746 | ||
1ea5fe8f | 747 | /* Copy debug stmts from DEST's chain of single predecessors up to |
748 | SRC, so that we don't lose the bindings as PHI nodes are introduced | |
749 | when DEST gains new predecessors. */ | |
80ed2d81 | 750 | void |
1ea5fe8f | 751 | propagate_threaded_block_debug_into (basic_block dest, basic_block src) |
752 | { | |
c64f38bf | 753 | if (!MAY_HAVE_DEBUG_BIND_STMTS) |
1ea5fe8f | 754 | return; |
755 | ||
756 | if (!single_pred_p (dest)) | |
757 | return; | |
758 | ||
759 | gcc_checking_assert (dest != src); | |
760 | ||
761 | gimple_stmt_iterator gsi = gsi_after_labels (dest); | |
9f27dbc3 | 762 | int i = 0; |
763 | const int alloc_count = 16; // ?? Should this be a PARAM? | |
1ea5fe8f | 764 | |
9f27dbc3 | 765 | /* Estimate the number of debug vars overridden in the beginning of |
766 | DEST, to tell how many we're going to need to begin with. */ | |
1ea5fe8f | 767 | for (gimple_stmt_iterator si = gsi; |
9f27dbc3 | 768 | i * 4 <= alloc_count * 3 && !gsi_end_p (si); gsi_next (&si)) |
769 | { | |
42acab1c | 770 | gimple *stmt = gsi_stmt (si); |
9f27dbc3 | 771 | if (!is_gimple_debug (stmt)) |
772 | break; | |
90567983 | 773 | if (gimple_debug_nonbind_marker_p (stmt)) |
774 | continue; | |
9f27dbc3 | 775 | i++; |
776 | } | |
777 | ||
4997014d | 778 | auto_vec<tree, alloc_count> fewvars; |
431205b7 | 779 | hash_set<tree> *vars = NULL; |
9f27dbc3 | 780 | |
781 | /* If we're already starting with 3/4 of alloc_count, go for a | |
431205b7 | 782 | hash_set, otherwise start with an unordered stack-allocated |
9f27dbc3 | 783 | VEC. */ |
784 | if (i * 4 > alloc_count * 3) | |
431205b7 | 785 | vars = new hash_set<tree>; |
9f27dbc3 | 786 | |
787 | /* Now go through the initial debug stmts in DEST again, this time | |
788 | actually inserting in VARS or FEWVARS. Don't bother checking for | |
789 | duplicates in FEWVARS. */ | |
790 | for (gimple_stmt_iterator si = gsi; !gsi_end_p (si); gsi_next (&si)) | |
1ea5fe8f | 791 | { |
42acab1c | 792 | gimple *stmt = gsi_stmt (si); |
1ea5fe8f | 793 | if (!is_gimple_debug (stmt)) |
794 | break; | |
795 | ||
796 | tree var; | |
797 | ||
798 | if (gimple_debug_bind_p (stmt)) | |
799 | var = gimple_debug_bind_get_var (stmt); | |
800 | else if (gimple_debug_source_bind_p (stmt)) | |
801 | var = gimple_debug_source_bind_get_var (stmt); | |
90567983 | 802 | else if (gimple_debug_nonbind_marker_p (stmt)) |
803 | continue; | |
1ea5fe8f | 804 | else |
805 | gcc_unreachable (); | |
806 | ||
9f27dbc3 | 807 | if (vars) |
431205b7 | 808 | vars->add (var); |
9f27dbc3 | 809 | else |
f1f41a6c | 810 | fewvars.quick_push (var); |
1ea5fe8f | 811 | } |
812 | ||
813 | basic_block bb = dest; | |
814 | ||
815 | do | |
816 | { | |
817 | bb = single_pred (bb); | |
818 | for (gimple_stmt_iterator si = gsi_last_bb (bb); | |
819 | !gsi_end_p (si); gsi_prev (&si)) | |
820 | { | |
42acab1c | 821 | gimple *stmt = gsi_stmt (si); |
1ea5fe8f | 822 | if (!is_gimple_debug (stmt)) |
823 | continue; | |
824 | ||
825 | tree var; | |
826 | ||
827 | if (gimple_debug_bind_p (stmt)) | |
828 | var = gimple_debug_bind_get_var (stmt); | |
829 | else if (gimple_debug_source_bind_p (stmt)) | |
830 | var = gimple_debug_source_bind_get_var (stmt); | |
90567983 | 831 | else if (gimple_debug_nonbind_marker_p (stmt)) |
832 | continue; | |
1ea5fe8f | 833 | else |
834 | gcc_unreachable (); | |
835 | ||
90567983 | 836 | /* Discard debug bind overlaps. Unlike stmts from src, |
1ea5fe8f | 837 | copied into a new block that will precede BB, debug bind |
838 | stmts in bypassed BBs may actually be discarded if | |
90567983 | 839 | they're overwritten by subsequent debug bind stmts. We |
840 | want to copy binds for all modified variables, so that we | |
841 | retain a bind to the shared def if there is one, or to a | |
842 | newly introduced PHI node if there is one. Our bind will | |
843 | end up reset if the value is dead, but that implies the | |
844 | variable couldn't have survived, so it's fine. We are | |
845 | not actually running the code that performed the binds at | |
846 | this point, we're just adding binds so that they survive | |
847 | the new confluence, so markers should not be copied. */ | |
431205b7 | 848 | if (vars && vars->add (var)) |
1ea5fe8f | 849 | continue; |
9f27dbc3 | 850 | else if (!vars) |
851 | { | |
f1f41a6c | 852 | int i = fewvars.length (); |
9f27dbc3 | 853 | while (i--) |
f1f41a6c | 854 | if (fewvars[i] == var) |
9f27dbc3 | 855 | break; |
856 | if (i >= 0) | |
857 | continue; | |
90567983 | 858 | else if (fewvars.length () < (unsigned) alloc_count) |
f1f41a6c | 859 | fewvars.quick_push (var); |
9f27dbc3 | 860 | else |
861 | { | |
431205b7 | 862 | vars = new hash_set<tree>; |
9f27dbc3 | 863 | for (i = 0; i < alloc_count; i++) |
431205b7 | 864 | vars->add (fewvars[i]); |
f1f41a6c | 865 | fewvars.release (); |
431205b7 | 866 | vars->add (var); |
9f27dbc3 | 867 | } |
868 | } | |
1ea5fe8f | 869 | |
870 | stmt = gimple_copy (stmt); | |
871 | /* ??? Should we drop the location of the copy to denote | |
872 | they're artificial bindings? */ | |
873 | gsi_insert_before (&gsi, stmt, GSI_NEW_STMT); | |
874 | } | |
875 | } | |
876 | while (bb != src && single_pred_p (bb)); | |
877 | ||
9f27dbc3 | 878 | if (vars) |
431205b7 | 879 | delete vars; |
f1f41a6c | 880 | else if (fewvars.exists ()) |
881 | fewvars.release (); | |
1ea5fe8f | 882 | } |
883 | ||
afdb7338 | 884 | /* See if TAKEN_EDGE->dest is a threadable block with no side effecs (ie, it |
885 | need not be duplicated as part of the CFG/SSA updating process). | |
886 | ||
887 | If it is threadable, add it to PATH and VISITED and recurse, ultimately | |
888 | returning TRUE from the toplevel call. Otherwise do nothing and | |
889 | return false. | |
890 | ||
be244ef5 | 891 | DUMMY_COND, SIMPLIFY are used to try and simplify the condition at the |
892 | end of TAKEN_EDGE->dest. | |
a8a97533 | 893 | |
894 | The available expression table is referenced via AVAIL_EXPRS_STACK. */ | |
895 | ||
afdb7338 | 896 | static bool |
897 | thread_around_empty_blocks (edge taken_edge, | |
1a91d914 | 898 | gcond *dummy_cond, |
a8a97533 | 899 | class avail_exprs_stack *avail_exprs_stack, |
a8a97533 | 900 | pfn_simplify simplify, |
afdb7338 | 901 | bitmap visited, |
a1965220 | 902 | vec<jump_thread_edge *> *path) |
42b013bc | 903 | { |
904 | basic_block bb = taken_edge->dest; | |
905 | gimple_stmt_iterator gsi; | |
42acab1c | 906 | gimple *stmt; |
42b013bc | 907 | tree cond; |
908 | ||
afdb7338 | 909 | /* The key property of these blocks is that they need not be duplicated |
f4d3c071 | 910 | when threading. Thus they cannot have visible side effects such |
afdb7338 | 911 | as PHI nodes. */ |
42b013bc | 912 | if (!gsi_end_p (gsi_start_phis (bb))) |
e2b72d6c | 913 | return false; |
42b013bc | 914 | |
915 | /* Skip over DEBUG statements at the start of the block. */ | |
916 | gsi = gsi_start_nondebug_bb (bb); | |
917 | ||
afdb7338 | 918 | /* If the block has no statements, but does have a single successor, then |
f7deb33d | 919 | it's just a forwarding block and we can thread through it trivially. |
bb66e2d1 | 920 | |
921 | However, note that just threading through empty blocks with single | |
922 | successors is not inherently profitable. For the jump thread to | |
923 | be profitable, we must avoid a runtime conditional. | |
924 | ||
925 | By taking the return value from the recursive call, we get the | |
926 | desired effect of returning TRUE when we found a profitable jump | |
f7deb33d | 927 | threading opportunity and FALSE otherwise. |
bb66e2d1 | 928 | |
929 | This is particularly important when this routine is called after | |
930 | processing a joiner block. Returning TRUE too aggressively in | |
931 | that case results in pointless duplication of the joiner block. */ | |
42b013bc | 932 | if (gsi_end_p (gsi)) |
afdb7338 | 933 | { |
934 | if (single_succ_p (bb)) | |
935 | { | |
936 | taken_edge = single_succ_edge (bb); | |
a1965220 | 937 | |
938 | if ((taken_edge->flags & EDGE_DFS_BACK) != 0) | |
939 | return false; | |
940 | ||
f3980d64 | 941 | if (!bitmap_bit_p (visited, taken_edge->dest->index)) |
afdb7338 | 942 | { |
0c5b289a | 943 | jump_thread_edge *x |
944 | = new jump_thread_edge (taken_edge, EDGE_NO_COPY_SRC_BLOCK); | |
945 | path->safe_push (x); | |
afdb7338 | 946 | bitmap_set_bit (visited, taken_edge->dest->index); |
bb66e2d1 | 947 | return thread_around_empty_blocks (taken_edge, |
948 | dummy_cond, | |
a8a97533 | 949 | avail_exprs_stack, |
bb66e2d1 | 950 | simplify, |
951 | visited, | |
a1965220 | 952 | path); |
afdb7338 | 953 | } |
954 | } | |
bb66e2d1 | 955 | |
956 | /* We have a block with no statements, but multiple successors? */ | |
afdb7338 | 957 | return false; |
958 | } | |
42b013bc | 959 | |
afdb7338 | 960 | /* The only real statements this block can have are a control |
961 | flow altering statement. Anything else stops the thread. */ | |
42b013bc | 962 | stmt = gsi_stmt (gsi); |
963 | if (gimple_code (stmt) != GIMPLE_COND | |
964 | && gimple_code (stmt) != GIMPLE_GOTO | |
965 | && gimple_code (stmt) != GIMPLE_SWITCH) | |
afdb7338 | 966 | return false; |
42b013bc | 967 | |
968 | /* Extract and simplify the condition. */ | |
a8a97533 | 969 | cond = simplify_control_stmt_condition (taken_edge, stmt, |
970 | avail_exprs_stack, dummy_cond, | |
be244ef5 | 971 | simplify); |
42b013bc | 972 | |
973 | /* If the condition can be statically computed and we have not already | |
974 | visited the destination edge, then add the taken edge to our thread | |
975 | path. */ | |
2abf3c4a | 976 | if (cond != NULL_TREE |
977 | && (is_gimple_min_invariant (cond) | |
978 | || TREE_CODE (cond) == CASE_LABEL_EXPR)) | |
42b013bc | 979 | { |
2abf3c4a | 980 | if (TREE_CODE (cond) == CASE_LABEL_EXPR) |
0fb4f2ce | 981 | taken_edge = find_edge (bb, label_to_block (cfun, CASE_LABEL (cond))); |
2abf3c4a | 982 | else |
983 | taken_edge = find_taken_edge (bb, cond); | |
42b013bc | 984 | |
a932d4bc | 985 | if (!taken_edge |
986 | || (taken_edge->flags & EDGE_DFS_BACK) != 0) | |
a1965220 | 987 | return false; |
988 | ||
42b013bc | 989 | if (bitmap_bit_p (visited, taken_edge->dest->index)) |
afdb7338 | 990 | return false; |
42b013bc | 991 | bitmap_set_bit (visited, taken_edge->dest->index); |
0c5b289a | 992 | |
993 | jump_thread_edge *x | |
994 | = new jump_thread_edge (taken_edge, EDGE_NO_COPY_SRC_BLOCK); | |
995 | path->safe_push (x); | |
996 | ||
afdb7338 | 997 | thread_around_empty_blocks (taken_edge, |
998 | dummy_cond, | |
a8a97533 | 999 | avail_exprs_stack, |
afdb7338 | 1000 | simplify, |
1001 | visited, | |
a1965220 | 1002 | path); |
afdb7338 | 1003 | return true; |
42b013bc | 1004 | } |
f7deb33d | 1005 | |
afdb7338 | 1006 | return false; |
42b013bc | 1007 | } |
f7deb33d | 1008 | |
62b180e1 | 1009 | /* We are exiting E->src, see if E->dest ends with a conditional |
48e1416a | 1010 | jump which has a known value when reached via E. |
62b180e1 | 1011 | |
f7deb33d | 1012 | E->dest can have arbitrary side effects which, if threading is |
1013 | successful, will be maintained. | |
1014 | ||
62b180e1 | 1015 | Special care is necessary if E is a back edge in the CFG as we |
1016 | may have already recorded equivalences for E->dest into our | |
1017 | various tables, including the result of the conditional at | |
1018 | the end of E->dest. Threading opportunities are severely | |
1019 | limited in that case to avoid short-circuiting the loop | |
1020 | incorrectly. | |
1021 | ||
d8a0d6b8 | 1022 | DUMMY_COND is a shared cond_expr used by condition simplification as scratch, |
1023 | to avoid allocating memory. | |
48e1416a | 1024 | |
d8a0d6b8 | 1025 | STACK is used to undo temporary equivalences created during the walk of |
1026 | E->dest. | |
1027 | ||
f7deb33d | 1028 | SIMPLIFY is a pass-specific function used to simplify statements. |
62b180e1 | 1029 | |
f7deb33d | 1030 | Our caller is responsible for restoring the state of the expression |
80ede13b | 1031 | and const_and_copies stacks. |
62b180e1 | 1032 | |
80ede13b | 1033 | Positive return value is success. Zero return value is failure, but |
1034 | the block can still be duplicated as a joiner in a jump thread path, | |
1035 | negative indicates the block should not be duplicated and thus is not | |
1036 | suitable for a joiner in a jump threading path. */ | |
1037 | ||
1038 | static int | |
f7deb33d | 1039 | thread_through_normal_block (edge e, |
1a91d914 | 1040 | gcond *dummy_cond, |
545372c5 | 1041 | const_and_copies *const_and_copies, |
a8a97533 | 1042 | avail_exprs_stack *avail_exprs_stack, |
4b69806c | 1043 | evrp_range_analyzer *evrp_range_analyzer, |
a8a97533 | 1044 | pfn_simplify simplify, |
4bc0f16e | 1045 | vec<jump_thread_edge *> *path, |
a1965220 | 1046 | bitmap visited) |
f7deb33d | 1047 | { |
9f4680b7 | 1048 | /* We want to record any equivalences created by traversing E. */ |
be244ef5 | 1049 | record_temporary_equivalences (e, const_and_copies, avail_exprs_stack); |
9f4680b7 | 1050 | |
2e920d0f | 1051 | /* PHIs create temporary equivalences. |
1052 | Note that if we found a PHI that made the block non-threadable, then | |
1053 | we need to bubble that up to our caller in the same manner we do | |
1054 | when we prematurely stop processing statements below. */ | |
4b69806c | 1055 | if (!record_temporary_equivalences_from_phis (e, const_and_copies, |
1056 | evrp_range_analyzer)) | |
2e920d0f | 1057 | return -1; |
62b180e1 | 1058 | |
1059 | /* Now walk each statement recording any context sensitive | |
1060 | temporary equivalences we can detect. */ | |
42acab1c | 1061 | gimple *stmt |
9964a983 | 1062 | = record_temporary_equivalences_from_stmts_at_dest (e, const_and_copies, |
a8a97533 | 1063 | avail_exprs_stack, |
4b69806c | 1064 | evrp_range_analyzer, |
694a1a82 | 1065 | simplify); |
80ede13b | 1066 | |
849b1089 | 1067 | /* There's two reasons STMT might be null, and distinguishing |
1068 | between them is important. | |
80ede13b | 1069 | |
849b1089 | 1070 | First the block may not have had any statements. For example, it |
1071 | might have some PHIs and unconditionally transfer control elsewhere. | |
1072 | Such blocks are suitable for jump threading, particularly as a | |
1073 | joiner block. | |
bb1779ad | 1074 | |
849b1089 | 1075 | The second reason would be if we did not process all the statements |
1076 | in the block (because there were too many to make duplicating the | |
1077 | block profitable. If we did not look at all the statements, then | |
1078 | we may not have invalidated everything needing invalidation. Thus | |
1079 | we must signal to our caller that this block is not suitable for | |
1080 | use as a joiner in a threading path. */ | |
1081 | if (!stmt) | |
1082 | { | |
1083 | /* First case. The statement simply doesn't have any instructions, but | |
1084 | does have PHIs. */ | |
1085 | if (gsi_end_p (gsi_start_nondebug_bb (e->dest)) | |
1086 | && !gsi_end_p (gsi_start_phis (e->dest))) | |
1087 | return 0; | |
1088 | ||
1089 | /* Second case. */ | |
1090 | return -1; | |
1091 | } | |
1c71d7c1 | 1092 | |
62b180e1 | 1093 | /* If we stopped at a COND_EXPR or SWITCH_EXPR, see if we know which arm |
1094 | will be taken. */ | |
75a70cf9 | 1095 | if (gimple_code (stmt) == GIMPLE_COND |
1096 | || gimple_code (stmt) == GIMPLE_GOTO | |
1097 | || gimple_code (stmt) == GIMPLE_SWITCH) | |
62b180e1 | 1098 | { |
1099 | tree cond; | |
1100 | ||
1101 | /* Extract and simplify the condition. */ | |
a8a97533 | 1102 | cond = simplify_control_stmt_condition (e, stmt, avail_exprs_stack, |
be244ef5 | 1103 | dummy_cond, simplify); |
62b180e1 | 1104 | |
ded1c768 | 1105 | if (!cond) |
1106 | return 0; | |
1107 | ||
2abf3c4a | 1108 | if (is_gimple_min_invariant (cond) |
1109 | || TREE_CODE (cond) == CASE_LABEL_EXPR) | |
62b180e1 | 1110 | { |
2abf3c4a | 1111 | edge taken_edge; |
1112 | if (TREE_CODE (cond) == CASE_LABEL_EXPR) | |
1113 | taken_edge = find_edge (e->dest, | |
0fb4f2ce | 1114 | label_to_block (cfun, CASE_LABEL (cond))); |
2abf3c4a | 1115 | else |
1116 | taken_edge = find_taken_edge (e->dest, cond); | |
1117 | ||
62b180e1 | 1118 | basic_block dest = (taken_edge ? taken_edge->dest : NULL); |
1119 | ||
afdb7338 | 1120 | /* DEST could be NULL for a computed jump to an absolute |
1121 | address. */ | |
f3980d64 | 1122 | if (dest == NULL |
1123 | || dest == e->dest | |
a1965220 | 1124 | || (taken_edge->flags & EDGE_DFS_BACK) != 0 |
f3980d64 | 1125 | || bitmap_bit_p (visited, dest->index)) |
80ede13b | 1126 | return 0; |
62b180e1 | 1127 | |
85309e9d | 1128 | /* Only push the EDGE_START_JUMP_THREAD marker if this is |
1129 | first edge on the path. */ | |
1130 | if (path->length () == 0) | |
1131 | { | |
1132 | jump_thread_edge *x | |
1133 | = new jump_thread_edge (e, EDGE_START_JUMP_THREAD); | |
1134 | path->safe_push (x); | |
85309e9d | 1135 | } |
0c5b289a | 1136 | |
85309e9d | 1137 | jump_thread_edge *x |
1138 | = new jump_thread_edge (taken_edge, EDGE_COPY_SRC_BLOCK); | |
f2981b08 | 1139 | path->safe_push (x); |
631d940c | 1140 | |
afdb7338 | 1141 | /* See if we can thread through DEST as well, this helps capture |
1142 | secondary effects of threading without having to re-run DOM or | |
1c71d7c1 | 1143 | VRP. |
c294418d | 1144 | |
1145 | We don't want to thread back to a block we have already | |
1146 | visited. This may be overly conservative. */ | |
1147 | bitmap_set_bit (visited, dest->index); | |
1148 | bitmap_set_bit (visited, e->dest->index); | |
1149 | thread_around_empty_blocks (taken_edge, | |
1150 | dummy_cond, | |
a8a97533 | 1151 | avail_exprs_stack, |
c294418d | 1152 | simplify, |
1153 | visited, | |
a1965220 | 1154 | path); |
80ede13b | 1155 | return 1; |
62b180e1 | 1156 | } |
1157 | } | |
80ede13b | 1158 | return 0; |
f7deb33d | 1159 | } |
1160 | ||
0a6c3056 | 1161 | /* There are basic blocks look like: |
1162 | <P0> | |
1163 | p0 = a CMP b ; or p0 = (INT) (a CMP b) | |
1164 | goto <X>; | |
1165 | ||
1166 | <P1> | |
1167 | p1 = c CMP d | |
1168 | goto <X>; | |
1169 | ||
1170 | <X> | |
1171 | # phi = PHI <p0 (P0), p1 (P1)> | |
1172 | if (phi != 0) goto <Y>; else goto <Z>; | |
1173 | ||
1174 | Then, edge (P0,X) or (P1,X) could be marked as EDGE_START_JUMP_THREAD | |
1175 | And edge (X,Y), (X,Z) is EDGE_COPY_SRC_JOINER_BLOCK | |
1176 | ||
1177 | Return true if E is (P0,X) or (P1,X) */ | |
1178 | ||
1179 | bool | |
1180 | edge_forwards_cmp_to_conditional_jump_through_empty_bb_p (edge e) | |
1181 | { | |
1182 | /* See if there is only one stmt which is gcond. */ | |
1183 | gcond *gs; | |
1184 | if (!(gs = safe_dyn_cast<gcond *> (last_and_only_stmt (e->dest)))) | |
1185 | return false; | |
1186 | ||
1187 | /* See if gcond's cond is "(phi !=/== 0/1)" in the basic block. */ | |
1188 | tree cond = gimple_cond_lhs (gs); | |
1189 | enum tree_code code = gimple_cond_code (gs); | |
1190 | tree rhs = gimple_cond_rhs (gs); | |
1191 | if (TREE_CODE (cond) != SSA_NAME | |
1192 | || (code != NE_EXPR && code != EQ_EXPR) | |
1193 | || (!integer_onep (rhs) && !integer_zerop (rhs))) | |
1194 | return false; | |
1195 | gphi *phi = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (cond)); | |
1196 | if (phi == NULL || gimple_bb (phi) != e->dest) | |
1197 | return false; | |
1198 | ||
1199 | /* Check if phi's incoming value is CMP. */ | |
1200 | gassign *def; | |
1201 | tree value = PHI_ARG_DEF_FROM_EDGE (phi, e); | |
1202 | if (TREE_CODE (value) != SSA_NAME | |
1203 | || !has_single_use (value) | |
1204 | || !(def = dyn_cast <gassign *> (SSA_NAME_DEF_STMT (value)))) | |
1205 | return false; | |
1206 | ||
1207 | /* Or if it is (INT) (a CMP b). */ | |
1208 | if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def))) | |
1209 | { | |
1210 | value = gimple_assign_rhs1 (def); | |
1211 | if (TREE_CODE (value) != SSA_NAME | |
1212 | || !has_single_use (value) | |
1213 | || !(def = dyn_cast<gassign *> (SSA_NAME_DEF_STMT (value)))) | |
1214 | return false; | |
1215 | } | |
1216 | ||
1217 | if (TREE_CODE_CLASS (gimple_assign_rhs_code (def)) != tcc_comparison) | |
1218 | return false; | |
1219 | ||
1220 | return true; | |
1221 | } | |
1222 | ||
f7deb33d | 1223 | /* We are exiting E->src, see if E->dest ends with a conditional |
1224 | jump which has a known value when reached via E. | |
1225 | ||
f7deb33d | 1226 | DUMMY_COND is a shared cond_expr used by condition simplification as scratch, |
1227 | to avoid allocating memory. | |
1228 | ||
a8a97533 | 1229 | CONST_AND_COPIES is used to undo temporary equivalences created during the |
1230 | walk of E->dest. | |
1231 | ||
1232 | The available expression table is referenced vai AVAIL_EXPRS_STACK. | |
f7deb33d | 1233 | |
1234 | SIMPLIFY is a pass-specific function used to simplify statements. */ | |
1235 | ||
57ee6051 | 1236 | static void |
1a91d914 | 1237 | thread_across_edge (gcond *dummy_cond, |
f7deb33d | 1238 | edge e, |
a8a97533 | 1239 | class const_and_copies *const_and_copies, |
1240 | class avail_exprs_stack *avail_exprs_stack, | |
4b69806c | 1241 | class evrp_range_analyzer *evrp_range_analyzer, |
57ee6051 | 1242 | pfn_simplify simplify) |
f7deb33d | 1243 | { |
4bc0f16e | 1244 | bitmap visited = BITMAP_ALLOC (NULL); |
1245 | ||
57ee6051 | 1246 | const_and_copies->push_marker (); |
1247 | avail_exprs_stack->push_marker (); | |
4b69806c | 1248 | if (evrp_range_analyzer) |
1249 | evrp_range_analyzer->push_marker (); | |
57ee6051 | 1250 | |
f7deb33d | 1251 | stmt_count = 0; |
1252 | ||
1253 | vec<jump_thread_edge *> *path = new vec<jump_thread_edge *> (); | |
4bc0f16e | 1254 | bitmap_clear (visited); |
1255 | bitmap_set_bit (visited, e->src->index); | |
1256 | bitmap_set_bit (visited, e->dest->index); | |
a1965220 | 1257 | |
1258 | int threaded; | |
1259 | if ((e->flags & EDGE_DFS_BACK) == 0) | |
1260 | threaded = thread_through_normal_block (e, dummy_cond, | |
a1965220 | 1261 | const_and_copies, |
1262 | avail_exprs_stack, | |
4b69806c | 1263 | evrp_range_analyzer, |
a1965220 | 1264 | simplify, path, |
1265 | visited); | |
1266 | else | |
1267 | threaded = 0; | |
1268 | ||
80ede13b | 1269 | if (threaded > 0) |
f7deb33d | 1270 | { |
1271 | propagate_threaded_block_debug_into (path->last ()->e->dest, | |
1272 | e->dest); | |
545372c5 | 1273 | const_and_copies->pop_to_marker (); |
57ee6051 | 1274 | avail_exprs_stack->pop_to_marker (); |
4b69806c | 1275 | if (evrp_range_analyzer) |
1276 | evrp_range_analyzer->pop_to_marker (); | |
4bc0f16e | 1277 | BITMAP_FREE (visited); |
f7deb33d | 1278 | register_jump_thread (path); |
1279 | return; | |
1280 | } | |
1281 | else | |
1282 | { | |
80ede13b | 1283 | /* Negative and zero return values indicate no threading was possible, |
1284 | thus there should be no edges on the thread path and no need to walk | |
1285 | through the vector entries. */ | |
f7deb33d | 1286 | gcc_assert (path->length () == 0); |
1287 | path->release (); | |
9b5a88db | 1288 | delete path; |
80ede13b | 1289 | |
1290 | /* A negative status indicates the target block was deemed too big to | |
1291 | duplicate. Just quit now rather than trying to use the block as | |
1292 | a joiner in a jump threading path. | |
1293 | ||
1294 | This prevents unnecessary code growth, but more importantly if we | |
1295 | do not look at all the statements in the block, then we may have | |
1296 | missed some invalidations if we had traversed a backedge! */ | |
1297 | if (threaded < 0) | |
1298 | { | |
1299 | BITMAP_FREE (visited); | |
545372c5 | 1300 | const_and_copies->pop_to_marker (); |
57ee6051 | 1301 | avail_exprs_stack->pop_to_marker (); |
4b69806c | 1302 | if (evrp_range_analyzer) |
1303 | evrp_range_analyzer->pop_to_marker (); | |
80ede13b | 1304 | return; |
1305 | } | |
f7deb33d | 1306 | } |
62b180e1 | 1307 | |
da81e0c5 | 1308 | /* We were unable to determine what out edge from E->dest is taken. However, |
1309 | we might still be able to thread through successors of E->dest. This | |
1310 | often occurs when E->dest is a joiner block which then fans back out | |
1311 | based on redundant tests. | |
1312 | ||
1313 | If so, we'll copy E->dest and redirect the appropriate predecessor to | |
1314 | the copy. Within the copy of E->dest, we'll thread one or more edges | |
1315 | to points deeper in the CFG. | |
1316 | ||
1317 | This is a stopgap until we have a more structured approach to path | |
1318 | isolation. */ | |
1319 | { | |
afdb7338 | 1320 | edge taken_edge; |
da81e0c5 | 1321 | edge_iterator ei; |
6da68a0a | 1322 | bool found; |
da81e0c5 | 1323 | |
ed4feca1 | 1324 | /* If E->dest has abnormal outgoing edges, then there's no guarantee |
1325 | we can safely redirect any of the edges. Just punt those cases. */ | |
1326 | FOR_EACH_EDGE (taken_edge, ei, e->dest->succs) | |
1327 | if (taken_edge->flags & EDGE_ABNORMAL) | |
1328 | { | |
545372c5 | 1329 | const_and_copies->pop_to_marker (); |
57ee6051 | 1330 | avail_exprs_stack->pop_to_marker (); |
4b69806c | 1331 | if (evrp_range_analyzer) |
1332 | evrp_range_analyzer->pop_to_marker (); | |
ed4feca1 | 1333 | BITMAP_FREE (visited); |
1334 | return; | |
1335 | } | |
1336 | ||
da81e0c5 | 1337 | /* Look at each successor of E->dest to see if we can thread through it. */ |
1338 | FOR_EACH_EDGE (taken_edge, ei, e->dest->succs) | |
1339 | { | |
a1965220 | 1340 | if ((e->flags & EDGE_DFS_BACK) != 0 |
1341 | || (taken_edge->flags & EDGE_DFS_BACK) != 0) | |
372172fe | 1342 | continue; |
a1965220 | 1343 | |
1a1e103f | 1344 | /* Push a fresh marker so we can unwind the equivalences created |
1345 | for each of E->dest's successors. */ | |
545372c5 | 1346 | const_and_copies->push_marker (); |
57ee6051 | 1347 | avail_exprs_stack->push_marker (); |
4b69806c | 1348 | if (evrp_range_analyzer) |
1349 | evrp_range_analyzer->push_marker (); | |
1c71d7c1 | 1350 | |
da81e0c5 | 1351 | /* Avoid threading to any block we have already visited. */ |
1352 | bitmap_clear (visited); | |
baec912e | 1353 | bitmap_set_bit (visited, e->src->index); |
da81e0c5 | 1354 | bitmap_set_bit (visited, e->dest->index); |
baec912e | 1355 | bitmap_set_bit (visited, taken_edge->dest->index); |
f2981b08 | 1356 | vec<jump_thread_edge *> *path = new vec<jump_thread_edge *> (); |
da81e0c5 | 1357 | |
1358 | /* Record whether or not we were able to thread through a successor | |
1359 | of E->dest. */ | |
0c5b289a | 1360 | jump_thread_edge *x = new jump_thread_edge (e, EDGE_START_JUMP_THREAD); |
f2981b08 | 1361 | path->safe_push (x); |
0c5b289a | 1362 | |
1363 | x = new jump_thread_edge (taken_edge, EDGE_COPY_SRC_JOINER_BLOCK); | |
f2981b08 | 1364 | path->safe_push (x); |
c294418d | 1365 | found = thread_around_empty_blocks (taken_edge, |
1366 | dummy_cond, | |
a8a97533 | 1367 | avail_exprs_stack, |
c294418d | 1368 | simplify, |
1369 | visited, | |
a1965220 | 1370 | path); |
c294418d | 1371 | |
1372 | if (!found) | |
559685be | 1373 | found = thread_through_normal_block (path->last ()->e, dummy_cond, |
a8a97533 | 1374 | const_and_copies, |
1375 | avail_exprs_stack, | |
4b69806c | 1376 | evrp_range_analyzer, |
a8a97533 | 1377 | simplify, path, |
a1965220 | 1378 | visited) > 0; |
559685be | 1379 | |
da81e0c5 | 1380 | /* If we were able to thread through a successor of E->dest, then |
1381 | record the jump threading opportunity. */ | |
0a6c3056 | 1382 | if (found |
1383 | || edge_forwards_cmp_to_conditional_jump_through_empty_bb_p (e)) | |
da81e0c5 | 1384 | { |
0a6c3056 | 1385 | if (taken_edge->dest != path->last ()->e->dest) |
1386 | propagate_threaded_block_debug_into (path->last ()->e->dest, | |
1387 | taken_edge->dest); | |
0c5b289a | 1388 | register_jump_thread (path); |
da81e0c5 | 1389 | } |
f2981b08 | 1390 | else |
372172fe | 1391 | delete_jump_thread_path (path); |
1a1e103f | 1392 | |
1393 | /* And unwind the equivalence table. */ | |
4b69806c | 1394 | if (evrp_range_analyzer) |
1395 | evrp_range_analyzer->pop_to_marker (); | |
57ee6051 | 1396 | avail_exprs_stack->pop_to_marker (); |
545372c5 | 1397 | const_and_copies->pop_to_marker (); |
da81e0c5 | 1398 | } |
1399 | BITMAP_FREE (visited); | |
1400 | } | |
1401 | ||
4b69806c | 1402 | if (evrp_range_analyzer) |
1403 | evrp_range_analyzer->pop_to_marker (); | |
545372c5 | 1404 | const_and_copies->pop_to_marker (); |
57ee6051 | 1405 | avail_exprs_stack->pop_to_marker (); |
1406 | } | |
1407 | ||
1408 | /* Examine the outgoing edges from BB and conditionally | |
1409 | try to thread them. | |
1410 | ||
1411 | DUMMY_COND is a shared cond_expr used by condition simplification as scratch, | |
1412 | to avoid allocating memory. | |
1413 | ||
1414 | CONST_AND_COPIES is used to undo temporary equivalences created during the | |
1415 | walk of E->dest. | |
1416 | ||
1417 | The available expression table is referenced vai AVAIL_EXPRS_STACK. | |
1418 | ||
1419 | SIMPLIFY is a pass-specific function used to simplify statements. */ | |
1420 | ||
1421 | void | |
1422 | thread_outgoing_edges (basic_block bb, gcond *dummy_cond, | |
1423 | class const_and_copies *const_and_copies, | |
1424 | class avail_exprs_stack *avail_exprs_stack, | |
4b69806c | 1425 | class evrp_range_analyzer *evrp_range_analyzer, |
57ee6051 | 1426 | tree (*simplify) (gimple *, gimple *, |
1427 | class avail_exprs_stack *, | |
1428 | basic_block)) | |
1429 | { | |
1430 | int flags = (EDGE_IGNORE | EDGE_COMPLEX | EDGE_ABNORMAL); | |
1431 | gimple *last; | |
1432 | ||
1433 | /* If we have an outgoing edge to a block with multiple incoming and | |
1434 | outgoing edges, then we may be able to thread the edge, i.e., we | |
1435 | may be able to statically determine which of the outgoing edges | |
1436 | will be traversed when the incoming edge from BB is traversed. */ | |
1437 | if (single_succ_p (bb) | |
1438 | && (single_succ_edge (bb)->flags & flags) == 0 | |
1439 | && potentially_threadable_block (single_succ (bb))) | |
1440 | { | |
1441 | thread_across_edge (dummy_cond, single_succ_edge (bb), | |
1442 | const_and_copies, avail_exprs_stack, | |
4b69806c | 1443 | evrp_range_analyzer, simplify); |
57ee6051 | 1444 | } |
1445 | else if ((last = last_stmt (bb)) | |
1446 | && gimple_code (last) == GIMPLE_COND | |
1447 | && EDGE_COUNT (bb->succs) == 2 | |
1448 | && (EDGE_SUCC (bb, 0)->flags & flags) == 0 | |
1449 | && (EDGE_SUCC (bb, 1)->flags & flags) == 0) | |
1450 | { | |
1451 | edge true_edge, false_edge; | |
1452 | ||
1453 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
1454 | ||
1455 | /* Only try to thread the edge if it reaches a target block with | |
1456 | more than one predecessor and more than one successor. */ | |
1457 | if (potentially_threadable_block (true_edge->dest)) | |
1458 | thread_across_edge (dummy_cond, true_edge, | |
4b69806c | 1459 | const_and_copies, avail_exprs_stack, |
1460 | evrp_range_analyzer, simplify); | |
57ee6051 | 1461 | |
1462 | /* Similarly for the ELSE arm. */ | |
1463 | if (potentially_threadable_block (false_edge->dest)) | |
1464 | thread_across_edge (dummy_cond, false_edge, | |
4b69806c | 1465 | const_and_copies, avail_exprs_stack, |
1466 | evrp_range_analyzer, simplify); | |
57ee6051 | 1467 | } |
62b180e1 | 1468 | } |