]>
Commit | Line | Data |
---|---|---|
4ee9c684 | 1 | /* SSA Dominator optimizations for trees |
3d3c2244 | 2 | Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, |
3 | 2011, 2012 Free Software Foundation, Inc. | |
4ee9c684 | 4 | Contributed by Diego Novillo <dnovillo@redhat.com> |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
8c4c00c1 | 10 | the Free Software Foundation; either version 3, or (at your option) |
4ee9c684 | 11 | any later version. |
12 | ||
13 | GCC is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 19 | along with GCC; see the file COPYING3. If not see |
20 | <http://www.gnu.org/licenses/>. */ | |
4ee9c684 | 21 | |
22 | #include "config.h" | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "tm.h" | |
26 | #include "tree.h" | |
27 | #include "flags.h" | |
4ee9c684 | 28 | #include "tm_p.h" |
4ee9c684 | 29 | #include "basic-block.h" |
388d1fc1 | 30 | #include "cfgloop.h" |
4ee9c684 | 31 | #include "function.h" |
ce084dfc | 32 | #include "gimple-pretty-print.h" |
4ee9c684 | 33 | #include "tree-flow.h" |
34 | #include "domwalk.h" | |
4ee9c684 | 35 | #include "tree-pass.h" |
7d564439 | 36 | #include "tree-ssa-propagate.h" |
4ee9c684 | 37 | #include "langhooks.h" |
cf024d22 | 38 | #include "params.h" |
4ee9c684 | 39 | |
40 | /* This file implements optimizations on the dominator tree. */ | |
41 | ||
75a70cf9 | 42 | /* Representation of a "naked" right-hand-side expression, to be used |
43 | in recording available expressions in the expression hash table. */ | |
44 | ||
45 | enum expr_kind | |
46 | { | |
47 | EXPR_SINGLE, | |
48 | EXPR_UNARY, | |
49 | EXPR_BINARY, | |
00f4f705 | 50 | EXPR_TERNARY, |
889ef038 | 51 | EXPR_CALL, |
52 | EXPR_PHI | |
75a70cf9 | 53 | }; |
54 | ||
55 | struct hashable_expr | |
56 | { | |
57 | tree type; | |
58 | enum expr_kind kind; | |
59 | union { | |
60 | struct { tree rhs; } single; | |
61 | struct { enum tree_code op; tree opnd; } unary; | |
00f4f705 | 62 | struct { enum tree_code op; tree opnd0, opnd1; } binary; |
63 | struct { enum tree_code op; tree opnd0, opnd1, opnd2; } ternary; | |
fb049fba | 64 | struct { gimple fn_from; bool pure; size_t nargs; tree *args; } call; |
889ef038 | 65 | struct { size_t nargs; tree *args; } phi; |
75a70cf9 | 66 | } ops; |
67 | }; | |
68 | ||
69 | /* Structure for recording known values of a conditional expression | |
70 | at the exits from its block. */ | |
71 | ||
7aab1427 | 72 | typedef struct cond_equivalence_s |
75a70cf9 | 73 | { |
74 | struct hashable_expr cond; | |
75 | tree value; | |
7aab1427 | 76 | } cond_equivalence; |
77 | ||
2f0993e7 | 78 | |
79 | /* Structure for recording edge equivalences as well as any pending | |
80 | edge redirections during the dominator optimizer. | |
81 | ||
82 | Computing and storing the edge equivalences instead of creating | |
83 | them on-demand can save significant amounts of time, particularly | |
48e1416a | 84 | for pathological cases involving switch statements. |
2f0993e7 | 85 | |
86 | These structures live for a single iteration of the dominator | |
87 | optimizer in the edge's AUX field. At the end of an iteration we | |
88 | free each of these structures and update the AUX field to point | |
89 | to any requested redirection target (the code for updating the | |
90 | CFG and SSA graph for edge redirection expects redirection edge | |
91 | targets to be in the AUX field for each edge. */ | |
92 | ||
93 | struct edge_info | |
94 | { | |
95 | /* If this edge creates a simple equivalence, the LHS and RHS of | |
96 | the equivalence will be stored here. */ | |
97 | tree lhs; | |
98 | tree rhs; | |
99 | ||
100 | /* Traversing an edge may also indicate one or more particular conditions | |
7aab1427 | 101 | are true or false. */ |
f1f41a6c | 102 | vec<cond_equivalence> cond_equivalences; |
2f0993e7 | 103 | }; |
104 | ||
4ee9c684 | 105 | /* Hash table with expressions made available during the renaming process. |
106 | When an assignment of the form X_i = EXPR is found, the statement is | |
107 | stored in this table. If the same expression EXPR is later found on the | |
108 | RHS of another statement, it is replaced with X_i (thus performing | |
109 | global redundancy elimination). Similarly as we pass through conditionals | |
110 | we record the conditional itself as having either a true or false value | |
111 | in this table. */ | |
112 | static htab_t avail_exprs; | |
113 | ||
9c629f0e | 114 | /* Stack of available expressions in AVAIL_EXPRs. Each block pushes any |
115 | expressions it enters into the hash table along with a marker entry | |
73645111 | 116 | (null). When we finish processing the block, we pop off entries and |
9c629f0e | 117 | remove the expressions from the global hash table until we hit the |
118 | marker. */ | |
75a70cf9 | 119 | typedef struct expr_hash_elt * expr_hash_elt_t; |
75a70cf9 | 120 | |
f1f41a6c | 121 | static vec<expr_hash_elt_t> avail_exprs_stack; |
9c629f0e | 122 | |
75a70cf9 | 123 | /* Structure for entries in the expression hash table. */ |
a8046f60 | 124 | |
4ee9c684 | 125 | struct expr_hash_elt |
126 | { | |
127 | /* The value (lhs) of this expression. */ | |
128 | tree lhs; | |
129 | ||
130 | /* The expression (rhs) we want to record. */ | |
75a70cf9 | 131 | struct hashable_expr expr; |
4ee9c684 | 132 | |
b66731e8 | 133 | /* The stmt pointer if this element corresponds to a statement. */ |
75a70cf9 | 134 | gimple stmt; |
4ee9c684 | 135 | |
75a70cf9 | 136 | /* The hash value for RHS. */ |
4ee9c684 | 137 | hashval_t hash; |
75a70cf9 | 138 | |
139 | /* A unique stamp, typically the address of the hash | |
140 | element itself, used in removing entries from the table. */ | |
141 | struct expr_hash_elt *stamp; | |
4ee9c684 | 142 | }; |
143 | ||
da43203c | 144 | /* Stack of dest,src pairs that need to be restored during finalization. |
145 | ||
146 | A NULL entry is used to mark the end of pairs which need to be | |
147 | restored during finalization of this block. */ | |
f1f41a6c | 148 | static vec<tree> const_and_copies_stack; |
da43203c | 149 | |
4ee9c684 | 150 | /* Track whether or not we have changed the control flow graph. */ |
151 | static bool cfg_altered; | |
152 | ||
35c15734 | 153 | /* Bitmap of blocks that have had EH statements cleaned. We should |
0870fd6e | 154 | remove their dead edges eventually. */ |
35c15734 | 155 | static bitmap need_eh_cleanup; |
156 | ||
4ee9c684 | 157 | /* Statistics for dominator optimizations. */ |
158 | struct opt_stats_d | |
159 | { | |
160 | long num_stmts; | |
161 | long num_exprs_considered; | |
162 | long num_re; | |
88dbf20f | 163 | long num_const_prop; |
164 | long num_copy_prop; | |
4ee9c684 | 165 | }; |
166 | ||
d0d897b6 | 167 | static struct opt_stats_d opt_stats; |
168 | ||
4ee9c684 | 169 | /* Local functions. */ |
6bf320fb | 170 | static void optimize_stmt (basic_block, gimple_stmt_iterator); |
75a70cf9 | 171 | static tree lookup_avail_expr (gimple, bool); |
4ee9c684 | 172 | static hashval_t avail_expr_hash (const void *); |
23ace16d | 173 | static hashval_t real_avail_expr_hash (const void *); |
4ee9c684 | 174 | static int avail_expr_eq (const void *, const void *); |
175 | static void htab_statistics (FILE *, htab_t); | |
7aab1427 | 176 | static void record_cond (cond_equivalence *); |
da43203c | 177 | static void record_const_or_copy (tree, tree); |
178 | static void record_equality (tree, tree); | |
2f0993e7 | 179 | static void record_equivalences_from_phis (basic_block); |
180 | static void record_equivalences_from_incoming_edge (basic_block); | |
e08ff65a | 181 | static void eliminate_redundant_computations (gimple_stmt_iterator *); |
75a70cf9 | 182 | static void record_equivalences_from_stmt (gimple, int); |
62b180e1 | 183 | static void dom_thread_across_edge (struct dom_walk_data *, edge); |
6bf320fb | 184 | static void dom_opt_leave_block (struct dom_walk_data *, basic_block); |
185 | static void dom_opt_enter_block (struct dom_walk_data *, basic_block); | |
9c629f0e | 186 | static void remove_local_expressions_from_table (void); |
da43203c | 187 | static void restore_vars_to_original_value (void); |
c0735efa | 188 | static edge single_incoming_edge_ignoring_loop_edges (basic_block); |
4ee9c684 | 189 | |
88dbf20f | 190 | |
75a70cf9 | 191 | /* Given a statement STMT, initialize the hash table element pointed to |
192 | by ELEMENT. */ | |
193 | ||
194 | static void | |
195 | initialize_hash_element (gimple stmt, tree lhs, | |
196 | struct expr_hash_elt *element) | |
197 | { | |
198 | enum gimple_code code = gimple_code (stmt); | |
199 | struct hashable_expr *expr = &element->expr; | |
200 | ||
201 | if (code == GIMPLE_ASSIGN) | |
202 | { | |
203 | enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
204 | ||
75a70cf9 | 205 | switch (get_gimple_rhs_class (subcode)) |
206 | { | |
207 | case GIMPLE_SINGLE_RHS: | |
00f4f705 | 208 | expr->kind = EXPR_SINGLE; |
6140195d | 209 | expr->type = TREE_TYPE (gimple_assign_rhs1 (stmt)); |
00f4f705 | 210 | expr->ops.single.rhs = gimple_assign_rhs1 (stmt); |
211 | break; | |
75a70cf9 | 212 | case GIMPLE_UNARY_RHS: |
00f4f705 | 213 | expr->kind = EXPR_UNARY; |
75a70cf9 | 214 | expr->type = TREE_TYPE (gimple_assign_lhs (stmt)); |
00f4f705 | 215 | expr->ops.unary.op = subcode; |
216 | expr->ops.unary.opnd = gimple_assign_rhs1 (stmt); | |
217 | break; | |
75a70cf9 | 218 | case GIMPLE_BINARY_RHS: |
00f4f705 | 219 | expr->kind = EXPR_BINARY; |
75a70cf9 | 220 | expr->type = TREE_TYPE (gimple_assign_lhs (stmt)); |
00f4f705 | 221 | expr->ops.binary.op = subcode; |
222 | expr->ops.binary.opnd0 = gimple_assign_rhs1 (stmt); | |
223 | expr->ops.binary.opnd1 = gimple_assign_rhs2 (stmt); | |
224 | break; | |
225 | case GIMPLE_TERNARY_RHS: | |
226 | expr->kind = EXPR_TERNARY; | |
227 | expr->type = TREE_TYPE (gimple_assign_lhs (stmt)); | |
228 | expr->ops.ternary.op = subcode; | |
229 | expr->ops.ternary.opnd0 = gimple_assign_rhs1 (stmt); | |
230 | expr->ops.ternary.opnd1 = gimple_assign_rhs2 (stmt); | |
231 | expr->ops.ternary.opnd2 = gimple_assign_rhs3 (stmt); | |
232 | break; | |
75a70cf9 | 233 | default: |
234 | gcc_unreachable (); | |
235 | } | |
236 | } | |
237 | else if (code == GIMPLE_COND) | |
238 | { | |
239 | expr->type = boolean_type_node; | |
240 | expr->kind = EXPR_BINARY; | |
241 | expr->ops.binary.op = gimple_cond_code (stmt); | |
242 | expr->ops.binary.opnd0 = gimple_cond_lhs (stmt); | |
243 | expr->ops.binary.opnd1 = gimple_cond_rhs (stmt); | |
244 | } | |
245 | else if (code == GIMPLE_CALL) | |
246 | { | |
247 | size_t nargs = gimple_call_num_args (stmt); | |
248 | size_t i; | |
249 | ||
250 | gcc_assert (gimple_call_lhs (stmt)); | |
251 | ||
252 | expr->type = TREE_TYPE (gimple_call_lhs (stmt)); | |
253 | expr->kind = EXPR_CALL; | |
fb049fba | 254 | expr->ops.call.fn_from = stmt; |
75a70cf9 | 255 | |
256 | if (gimple_call_flags (stmt) & (ECF_CONST | ECF_PURE)) | |
257 | expr->ops.call.pure = true; | |
48e1416a | 258 | else |
75a70cf9 | 259 | expr->ops.call.pure = false; |
260 | ||
261 | expr->ops.call.nargs = nargs; | |
889ef038 | 262 | expr->ops.call.args = XCNEWVEC (tree, nargs); |
75a70cf9 | 263 | for (i = 0; i < nargs; i++) |
264 | expr->ops.call.args[i] = gimple_call_arg (stmt, i); | |
265 | } | |
266 | else if (code == GIMPLE_SWITCH) | |
267 | { | |
268 | expr->type = TREE_TYPE (gimple_switch_index (stmt)); | |
269 | expr->kind = EXPR_SINGLE; | |
270 | expr->ops.single.rhs = gimple_switch_index (stmt); | |
271 | } | |
272 | else if (code == GIMPLE_GOTO) | |
273 | { | |
274 | expr->type = TREE_TYPE (gimple_goto_dest (stmt)); | |
275 | expr->kind = EXPR_SINGLE; | |
276 | expr->ops.single.rhs = gimple_goto_dest (stmt); | |
277 | } | |
889ef038 | 278 | else if (code == GIMPLE_PHI) |
279 | { | |
280 | size_t nargs = gimple_phi_num_args (stmt); | |
281 | size_t i; | |
282 | ||
283 | expr->type = TREE_TYPE (gimple_phi_result (stmt)); | |
284 | expr->kind = EXPR_PHI; | |
285 | expr->ops.phi.nargs = nargs; | |
286 | expr->ops.phi.args = XCNEWVEC (tree, nargs); | |
287 | ||
288 | for (i = 0; i < nargs; i++) | |
289 | expr->ops.phi.args[i] = gimple_phi_arg_def (stmt, i); | |
290 | } | |
75a70cf9 | 291 | else |
292 | gcc_unreachable (); | |
293 | ||
294 | element->lhs = lhs; | |
295 | element->stmt = stmt; | |
296 | element->hash = avail_expr_hash (element); | |
297 | element->stamp = element; | |
298 | } | |
299 | ||
300 | /* Given a conditional expression COND as a tree, initialize | |
301 | a hashable_expr expression EXPR. The conditional must be a | |
302 | comparison or logical negation. A constant or a variable is | |
303 | not permitted. */ | |
304 | ||
305 | static void | |
306 | initialize_expr_from_cond (tree cond, struct hashable_expr *expr) | |
307 | { | |
308 | expr->type = boolean_type_node; | |
48e1416a | 309 | |
75a70cf9 | 310 | if (COMPARISON_CLASS_P (cond)) |
311 | { | |
312 | expr->kind = EXPR_BINARY; | |
313 | expr->ops.binary.op = TREE_CODE (cond); | |
314 | expr->ops.binary.opnd0 = TREE_OPERAND (cond, 0); | |
315 | expr->ops.binary.opnd1 = TREE_OPERAND (cond, 1); | |
316 | } | |
317 | else if (TREE_CODE (cond) == TRUTH_NOT_EXPR) | |
318 | { | |
319 | expr->kind = EXPR_UNARY; | |
320 | expr->ops.unary.op = TRUTH_NOT_EXPR; | |
321 | expr->ops.unary.opnd = TREE_OPERAND (cond, 0); | |
322 | } | |
323 | else | |
324 | gcc_unreachable (); | |
325 | } | |
326 | ||
327 | /* Given a hashable_expr expression EXPR and an LHS, | |
328 | initialize the hash table element pointed to by ELEMENT. */ | |
329 | ||
330 | static void | |
331 | initialize_hash_element_from_expr (struct hashable_expr *expr, | |
332 | tree lhs, | |
333 | struct expr_hash_elt *element) | |
334 | { | |
335 | element->expr = *expr; | |
336 | element->lhs = lhs; | |
337 | element->stmt = NULL; | |
338 | element->hash = avail_expr_hash (element); | |
339 | element->stamp = element; | |
340 | } | |
341 | ||
342 | /* Compare two hashable_expr structures for equivalence. | |
343 | They are considered equivalent when the the expressions | |
344 | they denote must necessarily be equal. The logic is intended | |
345 | to follow that of operand_equal_p in fold-const.c */ | |
346 | ||
347 | static bool | |
348 | hashable_expr_equal_p (const struct hashable_expr *expr0, | |
349 | const struct hashable_expr *expr1) | |
350 | { | |
351 | tree type0 = expr0->type; | |
352 | tree type1 = expr1->type; | |
353 | ||
354 | /* If either type is NULL, there is nothing to check. */ | |
355 | if ((type0 == NULL_TREE) ^ (type1 == NULL_TREE)) | |
356 | return false; | |
357 | ||
358 | /* If both types don't have the same signedness, precision, and mode, | |
359 | then we can't consider them equal. */ | |
360 | if (type0 != type1 | |
361 | && (TREE_CODE (type0) == ERROR_MARK | |
362 | || TREE_CODE (type1) == ERROR_MARK | |
363 | || TYPE_UNSIGNED (type0) != TYPE_UNSIGNED (type1) | |
364 | || TYPE_PRECISION (type0) != TYPE_PRECISION (type1) | |
365 | || TYPE_MODE (type0) != TYPE_MODE (type1))) | |
366 | return false; | |
367 | ||
368 | if (expr0->kind != expr1->kind) | |
369 | return false; | |
370 | ||
371 | switch (expr0->kind) | |
372 | { | |
373 | case EXPR_SINGLE: | |
374 | return operand_equal_p (expr0->ops.single.rhs, | |
375 | expr1->ops.single.rhs, 0); | |
376 | ||
377 | case EXPR_UNARY: | |
378 | if (expr0->ops.unary.op != expr1->ops.unary.op) | |
379 | return false; | |
380 | ||
d9659041 | 381 | if ((CONVERT_EXPR_CODE_P (expr0->ops.unary.op) |
75a70cf9 | 382 | || expr0->ops.unary.op == NON_LVALUE_EXPR) |
383 | && TYPE_UNSIGNED (expr0->type) != TYPE_UNSIGNED (expr1->type)) | |
384 | return false; | |
385 | ||
386 | return operand_equal_p (expr0->ops.unary.opnd, | |
387 | expr1->ops.unary.opnd, 0); | |
388 | ||
389 | case EXPR_BINARY: | |
00f4f705 | 390 | if (expr0->ops.binary.op != expr1->ops.binary.op) |
391 | return false; | |
392 | ||
393 | if (operand_equal_p (expr0->ops.binary.opnd0, | |
394 | expr1->ops.binary.opnd0, 0) | |
395 | && operand_equal_p (expr0->ops.binary.opnd1, | |
396 | expr1->ops.binary.opnd1, 0)) | |
397 | return true; | |
398 | ||
399 | /* For commutative ops, allow the other order. */ | |
400 | return (commutative_tree_code (expr0->ops.binary.op) | |
401 | && operand_equal_p (expr0->ops.binary.opnd0, | |
402 | expr1->ops.binary.opnd1, 0) | |
403 | && operand_equal_p (expr0->ops.binary.opnd1, | |
404 | expr1->ops.binary.opnd0, 0)); | |
405 | ||
406 | case EXPR_TERNARY: | |
407 | if (expr0->ops.ternary.op != expr1->ops.ternary.op | |
408 | || !operand_equal_p (expr0->ops.ternary.opnd2, | |
409 | expr1->ops.ternary.opnd2, 0)) | |
410 | return false; | |
411 | ||
412 | if (operand_equal_p (expr0->ops.ternary.opnd0, | |
413 | expr1->ops.ternary.opnd0, 0) | |
414 | && operand_equal_p (expr0->ops.ternary.opnd1, | |
415 | expr1->ops.ternary.opnd1, 0)) | |
416 | return true; | |
417 | ||
418 | /* For commutative ops, allow the other order. */ | |
419 | return (commutative_ternary_tree_code (expr0->ops.ternary.op) | |
420 | && operand_equal_p (expr0->ops.ternary.opnd0, | |
421 | expr1->ops.ternary.opnd1, 0) | |
422 | && operand_equal_p (expr0->ops.ternary.opnd1, | |
423 | expr1->ops.ternary.opnd0, 0)); | |
75a70cf9 | 424 | |
425 | case EXPR_CALL: | |
426 | { | |
427 | size_t i; | |
428 | ||
429 | /* If the calls are to different functions, then they | |
430 | clearly cannot be equal. */ | |
fb049fba | 431 | if (!gimple_call_same_target_p (expr0->ops.call.fn_from, |
432 | expr1->ops.call.fn_from)) | |
75a70cf9 | 433 | return false; |
434 | ||
435 | if (! expr0->ops.call.pure) | |
436 | return false; | |
437 | ||
438 | if (expr0->ops.call.nargs != expr1->ops.call.nargs) | |
439 | return false; | |
440 | ||
441 | for (i = 0; i < expr0->ops.call.nargs; i++) | |
442 | if (! operand_equal_p (expr0->ops.call.args[i], | |
443 | expr1->ops.call.args[i], 0)) | |
444 | return false; | |
445 | ||
446 | return true; | |
447 | } | |
48e1416a | 448 | |
889ef038 | 449 | case EXPR_PHI: |
450 | { | |
451 | size_t i; | |
452 | ||
453 | if (expr0->ops.phi.nargs != expr1->ops.phi.nargs) | |
454 | return false; | |
455 | ||
456 | for (i = 0; i < expr0->ops.phi.nargs; i++) | |
457 | if (! operand_equal_p (expr0->ops.phi.args[i], | |
458 | expr1->ops.phi.args[i], 0)) | |
459 | return false; | |
460 | ||
461 | return true; | |
462 | } | |
463 | ||
75a70cf9 | 464 | default: |
465 | gcc_unreachable (); | |
466 | } | |
467 | } | |
468 | ||
469 | /* Compute a hash value for a hashable_expr value EXPR and a | |
470 | previously accumulated hash value VAL. If two hashable_expr | |
471 | values compare equal with hashable_expr_equal_p, they must | |
472 | hash to the same value, given an identical value of VAL. | |
473 | The logic is intended to follow iterative_hash_expr in tree.c. */ | |
474 | ||
475 | static hashval_t | |
476 | iterative_hash_hashable_expr (const struct hashable_expr *expr, hashval_t val) | |
477 | { | |
478 | switch (expr->kind) | |
479 | { | |
480 | case EXPR_SINGLE: | |
481 | val = iterative_hash_expr (expr->ops.single.rhs, val); | |
482 | break; | |
483 | ||
484 | case EXPR_UNARY: | |
485 | val = iterative_hash_object (expr->ops.unary.op, val); | |
486 | ||
487 | /* Make sure to include signedness in the hash computation. | |
488 | Don't hash the type, that can lead to having nodes which | |
489 | compare equal according to operand_equal_p, but which | |
490 | have different hash codes. */ | |
d9659041 | 491 | if (CONVERT_EXPR_CODE_P (expr->ops.unary.op) |
75a70cf9 | 492 | || expr->ops.unary.op == NON_LVALUE_EXPR) |
493 | val += TYPE_UNSIGNED (expr->type); | |
494 | ||
495 | val = iterative_hash_expr (expr->ops.unary.opnd, val); | |
496 | break; | |
497 | ||
498 | case EXPR_BINARY: | |
499 | val = iterative_hash_object (expr->ops.binary.op, val); | |
500 | if (commutative_tree_code (expr->ops.binary.op)) | |
00f4f705 | 501 | val = iterative_hash_exprs_commutative (expr->ops.binary.opnd0, |
502 | expr->ops.binary.opnd1, val); | |
75a70cf9 | 503 | else |
504 | { | |
505 | val = iterative_hash_expr (expr->ops.binary.opnd0, val); | |
506 | val = iterative_hash_expr (expr->ops.binary.opnd1, val); | |
507 | } | |
508 | break; | |
509 | ||
00f4f705 | 510 | case EXPR_TERNARY: |
511 | val = iterative_hash_object (expr->ops.ternary.op, val); | |
512 | if (commutative_ternary_tree_code (expr->ops.ternary.op)) | |
513 | val = iterative_hash_exprs_commutative (expr->ops.ternary.opnd0, | |
514 | expr->ops.ternary.opnd1, val); | |
515 | else | |
516 | { | |
517 | val = iterative_hash_expr (expr->ops.ternary.opnd0, val); | |
518 | val = iterative_hash_expr (expr->ops.ternary.opnd1, val); | |
519 | } | |
520 | val = iterative_hash_expr (expr->ops.ternary.opnd2, val); | |
521 | break; | |
522 | ||
75a70cf9 | 523 | case EXPR_CALL: |
524 | { | |
525 | size_t i; | |
526 | enum tree_code code = CALL_EXPR; | |
fb049fba | 527 | gimple fn_from; |
75a70cf9 | 528 | |
529 | val = iterative_hash_object (code, val); | |
fb049fba | 530 | fn_from = expr->ops.call.fn_from; |
531 | if (gimple_call_internal_p (fn_from)) | |
532 | val = iterative_hash_hashval_t | |
533 | ((hashval_t) gimple_call_internal_fn (fn_from), val); | |
534 | else | |
535 | val = iterative_hash_expr (gimple_call_fn (fn_from), val); | |
75a70cf9 | 536 | for (i = 0; i < expr->ops.call.nargs; i++) |
537 | val = iterative_hash_expr (expr->ops.call.args[i], val); | |
538 | } | |
539 | break; | |
48e1416a | 540 | |
889ef038 | 541 | case EXPR_PHI: |
542 | { | |
543 | size_t i; | |
544 | ||
545 | for (i = 0; i < expr->ops.phi.nargs; i++) | |
546 | val = iterative_hash_expr (expr->ops.phi.args[i], val); | |
547 | } | |
548 | break; | |
549 | ||
75a70cf9 | 550 | default: |
551 | gcc_unreachable (); | |
552 | } | |
553 | ||
554 | return val; | |
555 | } | |
556 | ||
557 | /* Print a diagnostic dump of an expression hash table entry. */ | |
558 | ||
559 | static void | |
560 | print_expr_hash_elt (FILE * stream, const struct expr_hash_elt *element) | |
561 | { | |
562 | if (element->stmt) | |
563 | fprintf (stream, "STMT "); | |
564 | else | |
565 | fprintf (stream, "COND "); | |
566 | ||
567 | if (element->lhs) | |
568 | { | |
569 | print_generic_expr (stream, element->lhs, 0); | |
570 | fprintf (stream, " = "); | |
571 | } | |
48e1416a | 572 | |
75a70cf9 | 573 | switch (element->expr.kind) |
574 | { | |
575 | case EXPR_SINGLE: | |
576 | print_generic_expr (stream, element->expr.ops.single.rhs, 0); | |
577 | break; | |
578 | ||
579 | case EXPR_UNARY: | |
580 | fprintf (stream, "%s ", tree_code_name[element->expr.ops.unary.op]); | |
581 | print_generic_expr (stream, element->expr.ops.unary.opnd, 0); | |
582 | break; | |
583 | ||
584 | case EXPR_BINARY: | |
585 | print_generic_expr (stream, element->expr.ops.binary.opnd0, 0); | |
586 | fprintf (stream, " %s ", tree_code_name[element->expr.ops.binary.op]); | |
587 | print_generic_expr (stream, element->expr.ops.binary.opnd1, 0); | |
588 | break; | |
589 | ||
00f4f705 | 590 | case EXPR_TERNARY: |
591 | fprintf (stream, " %s <", tree_code_name[element->expr.ops.ternary.op]); | |
592 | print_generic_expr (stream, element->expr.ops.ternary.opnd0, 0); | |
593 | fputs (", ", stream); | |
594 | print_generic_expr (stream, element->expr.ops.ternary.opnd1, 0); | |
595 | fputs (", ", stream); | |
596 | print_generic_expr (stream, element->expr.ops.ternary.opnd2, 0); | |
597 | fputs (">", stream); | |
598 | break; | |
599 | ||
75a70cf9 | 600 | case EXPR_CALL: |
601 | { | |
602 | size_t i; | |
603 | size_t nargs = element->expr.ops.call.nargs; | |
fb049fba | 604 | gimple fn_from; |
605 | ||
606 | fn_from = element->expr.ops.call.fn_from; | |
607 | if (gimple_call_internal_p (fn_from)) | |
608 | fputs (internal_fn_name (gimple_call_internal_fn (fn_from)), | |
609 | stream); | |
610 | else | |
611 | print_generic_expr (stream, gimple_call_fn (fn_from), 0); | |
75a70cf9 | 612 | fprintf (stream, " ("); |
613 | for (i = 0; i < nargs; i++) | |
614 | { | |
615 | print_generic_expr (stream, element->expr.ops.call.args[i], 0); | |
616 | if (i + 1 < nargs) | |
617 | fprintf (stream, ", "); | |
618 | } | |
619 | fprintf (stream, ")"); | |
620 | } | |
621 | break; | |
889ef038 | 622 | |
623 | case EXPR_PHI: | |
624 | { | |
625 | size_t i; | |
626 | size_t nargs = element->expr.ops.phi.nargs; | |
627 | ||
628 | fprintf (stream, "PHI <"); | |
629 | for (i = 0; i < nargs; i++) | |
630 | { | |
631 | print_generic_expr (stream, element->expr.ops.phi.args[i], 0); | |
632 | if (i + 1 < nargs) | |
633 | fprintf (stream, ", "); | |
634 | } | |
635 | fprintf (stream, ">"); | |
636 | } | |
637 | break; | |
75a70cf9 | 638 | } |
639 | fprintf (stream, "\n"); | |
640 | ||
641 | if (element->stmt) | |
642 | { | |
643 | fprintf (stream, " "); | |
644 | print_gimple_stmt (stream, element->stmt, 0, 0); | |
645 | } | |
646 | } | |
647 | ||
78d53e33 | 648 | /* Delete variable sized pieces of the expr_hash_elt ELEMENT. */ |
75a70cf9 | 649 | |
650 | static void | |
78d53e33 | 651 | free_expr_hash_elt_contents (struct expr_hash_elt *element) |
75a70cf9 | 652 | { |
75a70cf9 | 653 | if (element->expr.kind == EXPR_CALL) |
654 | free (element->expr.ops.call.args); | |
78d53e33 | 655 | else if (element->expr.kind == EXPR_PHI) |
889ef038 | 656 | free (element->expr.ops.phi.args); |
78d53e33 | 657 | } |
658 | ||
659 | /* Delete an expr_hash_elt and reclaim its storage. */ | |
889ef038 | 660 | |
78d53e33 | 661 | static void |
662 | free_expr_hash_elt (void *elt) | |
663 | { | |
664 | struct expr_hash_elt *element = ((struct expr_hash_elt *)elt); | |
665 | free_expr_hash_elt_contents (element); | |
75a70cf9 | 666 | free (element); |
667 | } | |
668 | ||
2f0993e7 | 669 | /* Allocate an EDGE_INFO for edge E and attach it to E. |
670 | Return the new EDGE_INFO structure. */ | |
671 | ||
672 | static struct edge_info * | |
673 | allocate_edge_info (edge e) | |
674 | { | |
675 | struct edge_info *edge_info; | |
676 | ||
945865c5 | 677 | edge_info = XCNEW (struct edge_info); |
2f0993e7 | 678 | |
679 | e->aux = edge_info; | |
680 | return edge_info; | |
681 | } | |
682 | ||
683 | /* Free all EDGE_INFO structures associated with edges in the CFG. | |
640e9781 | 684 | If a particular edge can be threaded, copy the redirection |
2f0993e7 | 685 | target from the EDGE_INFO structure into the edge's AUX field |
686 | as required by code to update the CFG and SSA graph for | |
687 | jump threading. */ | |
688 | ||
689 | static void | |
690 | free_all_edge_infos (void) | |
691 | { | |
692 | basic_block bb; | |
693 | edge_iterator ei; | |
694 | edge e; | |
695 | ||
696 | FOR_EACH_BB (bb) | |
697 | { | |
698 | FOR_EACH_EDGE (e, ei, bb->preds) | |
699 | { | |
945865c5 | 700 | struct edge_info *edge_info = (struct edge_info *) e->aux; |
2f0993e7 | 701 | |
702 | if (edge_info) | |
703 | { | |
f1f41a6c | 704 | edge_info->cond_equivalences.release (); |
2f0993e7 | 705 | free (edge_info); |
3cebc9d2 | 706 | e->aux = NULL; |
2f0993e7 | 707 | } |
708 | } | |
709 | } | |
710 | } | |
711 | ||
48e1416a | 712 | /* Jump threading, redundancy elimination and const/copy propagation. |
4ee9c684 | 713 | |
4ee9c684 | 714 | This pass may expose new symbols that need to be renamed into SSA. For |
715 | every new symbol exposed, its corresponding bit will be set in | |
591c2a30 | 716 | VARS_TO_RENAME. */ |
4ee9c684 | 717 | |
2a1990e9 | 718 | static unsigned int |
4ee9c684 | 719 | tree_ssa_dominator_optimize (void) |
720 | { | |
4ee9c684 | 721 | struct dom_walk_data walk_data; |
4ee9c684 | 722 | |
03ec6c0e | 723 | memset (&opt_stats, 0, sizeof (opt_stats)); |
724 | ||
4ee9c684 | 725 | /* Create our hash tables. */ |
75a70cf9 | 726 | avail_exprs = htab_create (1024, real_avail_expr_hash, avail_expr_eq, free_expr_hash_elt); |
f1f41a6c | 727 | avail_exprs_stack.create (20); |
728 | const_and_copies_stack.create (20); | |
27335ffd | 729 | need_eh_cleanup = BITMAP_ALLOC (NULL); |
4ee9c684 | 730 | |
731 | /* Setup callbacks for the generic dominator tree walker. */ | |
4ee9c684 | 732 | walk_data.dom_direction = CDI_DOMINATORS; |
180d0339 | 733 | walk_data.initialize_block_local_data = NULL; |
6bf320fb | 734 | walk_data.before_dom_children = dom_opt_enter_block; |
735 | walk_data.after_dom_children = dom_opt_leave_block; | |
4ee9c684 | 736 | /* Right now we only attach a dummy COND_EXPR to the global data pointer. |
737 | When we attach more stuff we'll need to fill this out with a real | |
738 | structure. */ | |
739 | walk_data.global_data = NULL; | |
180d0339 | 740 | walk_data.block_local_data_size = 0; |
4ee9c684 | 741 | |
742 | /* Now initialize the dominator walker. */ | |
743 | init_walk_dominator_tree (&walk_data); | |
744 | ||
4ee9c684 | 745 | calculate_dominance_info (CDI_DOMINATORS); |
9a17dd7d | 746 | cfg_altered = false; |
4ee9c684 | 747 | |
7e0311ae | 748 | /* We need to know loop structures in order to avoid destroying them |
749 | in jump threading. Note that we still can e.g. thread through loop | |
750 | headers to an exit edge, or through loop header to the loop body, assuming | |
751 | that we update the loop info. */ | |
752 | loop_optimizer_init (LOOPS_HAVE_SIMPLE_LATCHES); | |
388d1fc1 | 753 | |
f003f9fd | 754 | /* Initialize the value-handle array. */ |
755 | threadedge_initialize_values (); | |
756 | ||
62b180e1 | 757 | /* We need accurate information regarding back edges in the CFG |
f0b5f617 | 758 | for jump threading; this may include back edges that are not part of |
7e0311ae | 759 | a single loop. */ |
62b180e1 | 760 | mark_dfs_back_edges (); |
48e1416a | 761 | |
62b180e1 | 762 | /* Recursively walk the dominator tree optimizing statements. */ |
763 | walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); | |
4ee9c684 | 764 | |
62b180e1 | 765 | { |
75a70cf9 | 766 | gimple_stmt_iterator gsi; |
62b180e1 | 767 | basic_block bb; |
768 | FOR_EACH_BB (bb) | |
07eeb468 | 769 | { |
770 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
75a70cf9 | 771 | update_stmt_if_modified (gsi_stmt (gsi)); |
22aa74c4 | 772 | } |
62b180e1 | 773 | } |
0638045e | 774 | |
62b180e1 | 775 | /* If we exposed any new variables, go ahead and put them into |
776 | SSA form now, before we handle jump threading. This simplifies | |
777 | interactions between rewriting of _DECL nodes into SSA form | |
778 | and rewriting SSA_NAME nodes into SSA form after block | |
779 | duplication and CFG manipulation. */ | |
780 | update_ssa (TODO_update_ssa); | |
388d1fc1 | 781 | |
62b180e1 | 782 | free_all_edge_infos (); |
388d1fc1 | 783 | |
62b180e1 | 784 | /* Thread jumps, creating duplicate blocks as needed. */ |
7e0311ae | 785 | cfg_altered |= thread_through_all_blocks (first_pass_instance); |
4ee9c684 | 786 | |
9a17dd7d | 787 | if (cfg_altered) |
788 | free_dominance_info (CDI_DOMINATORS); | |
789 | ||
62b180e1 | 790 | /* Removal of statements may make some EH edges dead. Purge |
791 | such edges from the CFG as needed. */ | |
792 | if (!bitmap_empty_p (need_eh_cleanup)) | |
793 | { | |
5ec0139d | 794 | unsigned i; |
795 | bitmap_iterator bi; | |
796 | ||
797 | /* Jump threading may have created forwarder blocks from blocks | |
798 | needing EH cleanup; the new successor of these blocks, which | |
3d3c2244 | 799 | has inherited from the original block, needs the cleanup. |
800 | Don't clear bits in the bitmap, as that can break the bitmap | |
801 | iterator. */ | |
5ec0139d | 802 | EXECUTE_IF_SET_IN_BITMAP (need_eh_cleanup, 0, i, bi) |
803 | { | |
804 | basic_block bb = BASIC_BLOCK (i); | |
3d3c2244 | 805 | if (bb == NULL) |
806 | continue; | |
807 | while (single_succ_p (bb) | |
808 | && (single_succ_edge (bb)->flags & EDGE_EH) == 0) | |
809 | bb = single_succ (bb); | |
810 | if (bb == EXIT_BLOCK_PTR) | |
811 | continue; | |
812 | if ((unsigned) bb->index != i) | |
813 | bitmap_set_bit (need_eh_cleanup, bb->index); | |
5ec0139d | 814 | } |
815 | ||
75a70cf9 | 816 | gimple_purge_all_dead_eh_edges (need_eh_cleanup); |
53c5d9d4 | 817 | bitmap_clear (need_eh_cleanup); |
62b180e1 | 818 | } |
4ee9c684 | 819 | |
581f8050 | 820 | statistics_counter_event (cfun, "Redundant expressions eliminated", |
821 | opt_stats.num_re); | |
822 | statistics_counter_event (cfun, "Constants propagated", | |
823 | opt_stats.num_const_prop); | |
824 | statistics_counter_event (cfun, "Copies propagated", | |
825 | opt_stats.num_copy_prop); | |
826 | ||
4ee9c684 | 827 | /* Debugging dumps. */ |
828 | if (dump_file && (dump_flags & TDF_STATS)) | |
829 | dump_dominator_optimization_stats (dump_file); | |
830 | ||
7e0311ae | 831 | loop_optimizer_finalize (); |
832 | ||
62b180e1 | 833 | /* Delete our main hashtable. */ |
4ee9c684 | 834 | htab_delete (avail_exprs); |
4ee9c684 | 835 | |
836 | /* And finalize the dominator walker. */ | |
837 | fini_walk_dominator_tree (&walk_data); | |
a8ddfbad | 838 | |
8dbf774a | 839 | /* Free asserted bitmaps and stacks. */ |
27335ffd | 840 | BITMAP_FREE (need_eh_cleanup); |
48e1416a | 841 | |
f1f41a6c | 842 | avail_exprs_stack.release (); |
843 | const_and_copies_stack.release (); | |
48e1416a | 844 | |
f003f9fd | 845 | /* Free the value-handle array. */ |
846 | threadedge_finalize_values (); | |
f1f41a6c | 847 | ssa_name_values.release (); |
f003f9fd | 848 | |
2a1990e9 | 849 | return 0; |
4ee9c684 | 850 | } |
851 | ||
852 | static bool | |
853 | gate_dominator (void) | |
854 | { | |
855 | return flag_tree_dom != 0; | |
856 | } | |
857 | ||
48e1416a | 858 | struct gimple_opt_pass pass_dominator = |
4ee9c684 | 859 | { |
20099e35 | 860 | { |
861 | GIMPLE_PASS, | |
4ee9c684 | 862 | "dom", /* name */ |
c7875731 | 863 | OPTGROUP_NONE, /* optinfo_flags */ |
4ee9c684 | 864 | gate_dominator, /* gate */ |
865 | tree_ssa_dominator_optimize, /* execute */ | |
866 | NULL, /* sub */ | |
867 | NULL, /* next */ | |
868 | 0, /* static_pass_number */ | |
869 | TV_TREE_SSA_DOMINATOR_OPTS, /* tv_id */ | |
2f8eb909 | 870 | PROP_cfg | PROP_ssa, /* properties_required */ |
4ee9c684 | 871 | 0, /* properties_provided */ |
b6246c40 | 872 | 0, /* properties_destroyed */ |
4ee9c684 | 873 | 0, /* todo_flags_start */ |
a2676c4f | 874 | TODO_cleanup_cfg |
88dbf20f | 875 | | TODO_update_ssa |
a2676c4f | 876 | | TODO_verify_ssa |
771e2890 | 877 | | TODO_verify_flow /* todo_flags_finish */ |
20099e35 | 878 | } |
4ee9c684 | 879 | }; |
880 | ||
881 | ||
75a70cf9 | 882 | /* Given a conditional statement CONDSTMT, convert the |
883 | condition to a canonical form. */ | |
54aceb26 | 884 | |
885 | static void | |
75a70cf9 | 886 | canonicalize_comparison (gimple condstmt) |
54aceb26 | 887 | { |
54aceb26 | 888 | tree op0; |
889 | tree op1; | |
75a70cf9 | 890 | enum tree_code code; |
54aceb26 | 891 | |
75a70cf9 | 892 | gcc_assert (gimple_code (condstmt) == GIMPLE_COND); |
54aceb26 | 893 | |
75a70cf9 | 894 | op0 = gimple_cond_lhs (condstmt); |
895 | op1 = gimple_cond_rhs (condstmt); | |
896 | ||
897 | code = gimple_cond_code (condstmt); | |
54aceb26 | 898 | |
899 | /* If it would be profitable to swap the operands, then do so to | |
900 | canonicalize the statement, enabling better optimization. | |
901 | ||
902 | By placing canonicalization of such expressions here we | |
903 | transparently keep statements in canonical form, even | |
904 | when the statement is modified. */ | |
905 | if (tree_swap_operands_p (op0, op1, false)) | |
906 | { | |
907 | /* For relationals we need to swap the operands | |
908 | and change the code. */ | |
909 | if (code == LT_EXPR | |
910 | || code == GT_EXPR | |
911 | || code == LE_EXPR | |
912 | || code == GE_EXPR) | |
913 | { | |
75a70cf9 | 914 | code = swap_tree_comparison (code); |
915 | ||
916 | gimple_cond_set_code (condstmt, code); | |
917 | gimple_cond_set_lhs (condstmt, op1); | |
918 | gimple_cond_set_rhs (condstmt, op0); | |
919 | ||
920 | update_stmt (condstmt); | |
54aceb26 | 921 | } |
922 | } | |
923 | } | |
4ee9c684 | 924 | |
4ee9c684 | 925 | /* Initialize local stacks for this optimizer and record equivalences |
926 | upon entry to BB. Equivalences can come from the edge traversed to | |
927 | reach BB or they may come from PHI nodes at the start of BB. */ | |
928 | ||
4ee9c684 | 929 | /* Remove all the expressions in LOCALS from TABLE, stopping when there are |
930 | LIMIT entries left in LOCALs. */ | |
931 | ||
932 | static void | |
9c629f0e | 933 | remove_local_expressions_from_table (void) |
4ee9c684 | 934 | { |
4ee9c684 | 935 | /* Remove all the expressions made available in this block. */ |
f1f41a6c | 936 | while (avail_exprs_stack.length () > 0) |
4ee9c684 | 937 | { |
f1f41a6c | 938 | expr_hash_elt_t victim = avail_exprs_stack.pop (); |
04c3b49f | 939 | void **slot; |
9c629f0e | 940 | |
75a70cf9 | 941 | if (victim == NULL) |
9c629f0e | 942 | break; |
4ee9c684 | 943 | |
75a70cf9 | 944 | /* This must precede the actual removal from the hash table, |
945 | as ELEMENT and the table entry may share a call argument | |
946 | vector which will be freed during removal. */ | |
947 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
948 | { | |
949 | fprintf (dump_file, "<<<< "); | |
04c3b49f | 950 | print_expr_hash_elt (dump_file, victim); |
75a70cf9 | 951 | } |
952 | ||
04c3b49f | 953 | slot = htab_find_slot_with_hash (avail_exprs, |
954 | victim, victim->hash, NO_INSERT); | |
955 | gcc_assert (slot && *slot == (void *) victim); | |
956 | htab_clear_slot (avail_exprs, slot); | |
4ee9c684 | 957 | } |
958 | } | |
959 | ||
da43203c | 960 | /* Use the source/dest pairs in CONST_AND_COPIES_STACK to restore |
961 | CONST_AND_COPIES to its original state, stopping when we hit a | |
962 | NULL marker. */ | |
4ee9c684 | 963 | |
964 | static void | |
da43203c | 965 | restore_vars_to_original_value (void) |
4ee9c684 | 966 | { |
f1f41a6c | 967 | while (const_and_copies_stack.length () > 0) |
4ee9c684 | 968 | { |
969 | tree prev_value, dest; | |
970 | ||
f1f41a6c | 971 | dest = const_and_copies_stack.pop (); |
4ee9c684 | 972 | |
da43203c | 973 | if (dest == NULL) |
974 | break; | |
975 | ||
75a70cf9 | 976 | if (dump_file && (dump_flags & TDF_DETAILS)) |
977 | { | |
978 | fprintf (dump_file, "<<<< COPY "); | |
979 | print_generic_expr (dump_file, dest, 0); | |
980 | fprintf (dump_file, " = "); | |
981 | print_generic_expr (dump_file, SSA_NAME_VALUE (dest), 0); | |
982 | fprintf (dump_file, "\n"); | |
983 | } | |
984 | ||
f1f41a6c | 985 | prev_value = const_and_copies_stack.pop (); |
f003f9fd | 986 | set_ssa_name_value (dest, prev_value); |
4ee9c684 | 987 | } |
988 | } | |
989 | ||
62b180e1 | 990 | /* A trivial wrapper so that we can present the generic jump |
991 | threading code with a simple API for simplifying statements. */ | |
992 | static tree | |
75a70cf9 | 993 | simplify_stmt_for_jump_threading (gimple stmt, |
994 | gimple within_stmt ATTRIBUTE_UNUSED) | |
62b180e1 | 995 | { |
996 | return lookup_avail_expr (stmt, false); | |
997 | } | |
998 | ||
999 | /* Wrapper for common code to attempt to thread an edge. For example, | |
1000 | it handles lazily building the dummy condition and the bookkeeping | |
1001 | when jump threading is successful. */ | |
1002 | ||
1003 | static void | |
1004 | dom_thread_across_edge (struct dom_walk_data *walk_data, edge e) | |
1005 | { | |
62b180e1 | 1006 | if (! walk_data->global_data) |
75a70cf9 | 1007 | { |
1008 | gimple dummy_cond = | |
1009 | gimple_build_cond (NE_EXPR, | |
1010 | integer_zero_node, integer_zero_node, | |
1011 | NULL, NULL); | |
1012 | walk_data->global_data = dummy_cond; | |
1013 | } | |
62b180e1 | 1014 | |
75a70cf9 | 1015 | thread_across_edge ((gimple) walk_data->global_data, e, false, |
62b180e1 | 1016 | &const_and_copies_stack, |
1017 | simplify_stmt_for_jump_threading); | |
1018 | } | |
1019 | ||
4ee9c684 | 1020 | /* PHI nodes can create equivalences too. |
1021 | ||
1022 | Ignoring any alternatives which are the same as the result, if | |
1023 | all the alternatives are equal, then the PHI node creates an | |
8dbf774a | 1024 | equivalence. */ |
6e9a4371 | 1025 | |
4ee9c684 | 1026 | static void |
2f0993e7 | 1027 | record_equivalences_from_phis (basic_block bb) |
4ee9c684 | 1028 | { |
75a70cf9 | 1029 | gimple_stmt_iterator gsi; |
48e1416a | 1030 | |
75a70cf9 | 1031 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
4ee9c684 | 1032 | { |
75a70cf9 | 1033 | gimple phi = gsi_stmt (gsi); |
1034 | ||
1035 | tree lhs = gimple_phi_result (phi); | |
4ee9c684 | 1036 | tree rhs = NULL; |
75a70cf9 | 1037 | size_t i; |
4ee9c684 | 1038 | |
75a70cf9 | 1039 | for (i = 0; i < gimple_phi_num_args (phi); i++) |
4ee9c684 | 1040 | { |
75a70cf9 | 1041 | tree t = gimple_phi_arg_def (phi, i); |
4ee9c684 | 1042 | |
2fb4af30 | 1043 | /* Ignore alternatives which are the same as our LHS. Since |
1044 | LHS is a PHI_RESULT, it is known to be a SSA_NAME, so we | |
1045 | can simply compare pointers. */ | |
fcf57fc2 | 1046 | if (lhs == t) |
92527855 | 1047 | continue; |
1048 | ||
1049 | /* If we have not processed an alternative yet, then set | |
1050 | RHS to this alternative. */ | |
1051 | if (rhs == NULL) | |
1052 | rhs = t; | |
1053 | /* If we have processed an alternative (stored in RHS), then | |
1054 | see if it is equal to this one. If it isn't, then stop | |
1055 | the search. */ | |
1056 | else if (! operand_equal_for_phi_arg_p (rhs, t)) | |
4ee9c684 | 1057 | break; |
1058 | } | |
1059 | ||
1060 | /* If we had no interesting alternatives, then all the RHS alternatives | |
1061 | must have been the same as LHS. */ | |
1062 | if (!rhs) | |
1063 | rhs = lhs; | |
1064 | ||
1065 | /* If we managed to iterate through each PHI alternative without | |
1066 | breaking out of the loop, then we have a PHI which may create | |
1067 | a useful equivalence. We do not need to record unwind data for | |
1068 | this, since this is a true assignment and not an equivalence | |
365db11e | 1069 | inferred from a comparison. All uses of this ssa name are dominated |
4ee9c684 | 1070 | by this assignment, so unwinding just costs time and space. */ |
75a70cf9 | 1071 | if (i == gimple_phi_num_args (phi) && may_propagate_copy (lhs, rhs)) |
f003f9fd | 1072 | set_ssa_name_value (lhs, rhs); |
4ee9c684 | 1073 | } |
1074 | } | |
1075 | ||
c0735efa | 1076 | /* Ignoring loop backedges, if BB has precisely one incoming edge then |
1077 | return that edge. Otherwise return NULL. */ | |
1078 | static edge | |
1079 | single_incoming_edge_ignoring_loop_edges (basic_block bb) | |
1080 | { | |
1081 | edge retval = NULL; | |
1082 | edge e; | |
cd665a06 | 1083 | edge_iterator ei; |
c0735efa | 1084 | |
cd665a06 | 1085 | FOR_EACH_EDGE (e, ei, bb->preds) |
c0735efa | 1086 | { |
1087 | /* A loop back edge can be identified by the destination of | |
1088 | the edge dominating the source of the edge. */ | |
1089 | if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) | |
1090 | continue; | |
1091 | ||
1092 | /* If we have already seen a non-loop edge, then we must have | |
1093 | multiple incoming non-loop edges and thus we return NULL. */ | |
1094 | if (retval) | |
1095 | return NULL; | |
1096 | ||
1097 | /* This is the first non-loop incoming edge we have found. Record | |
1098 | it. */ | |
1099 | retval = e; | |
1100 | } | |
1101 | ||
1102 | return retval; | |
1103 | } | |
1104 | ||
4ee9c684 | 1105 | /* Record any equivalences created by the incoming edge to BB. If BB |
1106 | has more than one incoming edge, then no equivalence is created. */ | |
1107 | ||
1108 | static void | |
2f0993e7 | 1109 | record_equivalences_from_incoming_edge (basic_block bb) |
4ee9c684 | 1110 | { |
2f0993e7 | 1111 | edge e; |
4ee9c684 | 1112 | basic_block parent; |
2f0993e7 | 1113 | struct edge_info *edge_info; |
4ee9c684 | 1114 | |
0975351b | 1115 | /* If our parent block ended with a control statement, then we may be |
4ee9c684 | 1116 | able to record some equivalences based on which outgoing edge from |
1117 | the parent was followed. */ | |
1118 | parent = get_immediate_dominator (CDI_DOMINATORS, bb); | |
4ee9c684 | 1119 | |
2f0993e7 | 1120 | e = single_incoming_edge_ignoring_loop_edges (bb); |
4ee9c684 | 1121 | |
2f0993e7 | 1122 | /* If we had a single incoming edge from our parent block, then enter |
1123 | any data associated with the edge into our tables. */ | |
1124 | if (e && e->src == parent) | |
4ee9c684 | 1125 | { |
2f0993e7 | 1126 | unsigned int i; |
4ee9c684 | 1127 | |
945865c5 | 1128 | edge_info = (struct edge_info *) e->aux; |
4ee9c684 | 1129 | |
2f0993e7 | 1130 | if (edge_info) |
4ee9c684 | 1131 | { |
2f0993e7 | 1132 | tree lhs = edge_info->lhs; |
1133 | tree rhs = edge_info->rhs; | |
7aab1427 | 1134 | cond_equivalence *eq; |
2f0993e7 | 1135 | |
1136 | if (lhs) | |
1137 | record_equality (lhs, rhs); | |
1138 | ||
f1f41a6c | 1139 | for (i = 0; edge_info->cond_equivalences.iterate (i, &eq); ++i) |
7aab1427 | 1140 | record_cond (eq); |
4ee9c684 | 1141 | } |
1142 | } | |
4ee9c684 | 1143 | } |
1144 | ||
1145 | /* Dump SSA statistics on FILE. */ | |
1146 | ||
1147 | void | |
1148 | dump_dominator_optimization_stats (FILE *file) | |
1149 | { | |
4ee9c684 | 1150 | fprintf (file, "Total number of statements: %6ld\n\n", |
1151 | opt_stats.num_stmts); | |
1152 | fprintf (file, "Exprs considered for dominator optimizations: %6ld\n", | |
1153 | opt_stats.num_exprs_considered); | |
1154 | ||
4ee9c684 | 1155 | fprintf (file, "\nHash table statistics:\n"); |
1156 | ||
1157 | fprintf (file, " avail_exprs: "); | |
1158 | htab_statistics (file, avail_exprs); | |
1159 | } | |
1160 | ||
1161 | ||
1162 | /* Dump SSA statistics on stderr. */ | |
1163 | ||
4b987fac | 1164 | DEBUG_FUNCTION void |
4ee9c684 | 1165 | debug_dominator_optimization_stats (void) |
1166 | { | |
1167 | dump_dominator_optimization_stats (stderr); | |
1168 | } | |
1169 | ||
1170 | ||
1171 | /* Dump statistics for the hash table HTAB. */ | |
1172 | ||
1173 | static void | |
1174 | htab_statistics (FILE *file, htab_t htab) | |
1175 | { | |
1176 | fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n", | |
1177 | (long) htab_size (htab), | |
1178 | (long) htab_elements (htab), | |
1179 | htab_collisions (htab)); | |
1180 | } | |
1181 | ||
75a70cf9 | 1182 | |
1183 | /* Enter condition equivalence into the expression hash table. | |
1184 | This indicates that a conditional expression has a known | |
1185 | boolean value. */ | |
4ee9c684 | 1186 | |
1187 | static void | |
7aab1427 | 1188 | record_cond (cond_equivalence *p) |
4ee9c684 | 1189 | { |
945865c5 | 1190 | struct expr_hash_elt *element = XCNEW (struct expr_hash_elt); |
4ee9c684 | 1191 | void **slot; |
1192 | ||
75a70cf9 | 1193 | initialize_hash_element_from_expr (&p->cond, p->value, element); |
4ee9c684 | 1194 | |
1195 | slot = htab_find_slot_with_hash (avail_exprs, (void *)element, | |
67c4f309 | 1196 | element->hash, INSERT); |
4ee9c684 | 1197 | if (*slot == NULL) |
1198 | { | |
1199 | *slot = (void *) element; | |
75a70cf9 | 1200 | |
1201 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1202 | { | |
1203 | fprintf (dump_file, "1>>> "); | |
1204 | print_expr_hash_elt (dump_file, element); | |
1205 | } | |
1206 | ||
f1f41a6c | 1207 | avail_exprs_stack.safe_push (element); |
4ee9c684 | 1208 | } |
1209 | else | |
78d53e33 | 1210 | free_expr_hash_elt (element); |
4ee9c684 | 1211 | } |
1212 | ||
75a70cf9 | 1213 | /* Build a cond_equivalence record indicating that the comparison |
7aab1427 | 1214 | CODE holds between operands OP0 and OP1 and push it to **P. */ |
48e1416a | 1215 | |
2f0993e7 | 1216 | static void |
75a70cf9 | 1217 | build_and_record_new_cond (enum tree_code code, |
1218 | tree op0, tree op1, | |
f1f41a6c | 1219 | vec<cond_equivalence> *p) |
2f0993e7 | 1220 | { |
7aab1427 | 1221 | cond_equivalence c; |
1222 | struct hashable_expr *cond = &c.cond; | |
75a70cf9 | 1223 | |
1224 | gcc_assert (TREE_CODE_CLASS (code) == tcc_comparison); | |
1225 | ||
1226 | cond->type = boolean_type_node; | |
1227 | cond->kind = EXPR_BINARY; | |
1228 | cond->ops.binary.op = code; | |
1229 | cond->ops.binary.opnd0 = op0; | |
1230 | cond->ops.binary.opnd1 = op1; | |
1231 | ||
7aab1427 | 1232 | c.value = boolean_true_node; |
f1f41a6c | 1233 | p->safe_push (c); |
2f0993e7 | 1234 | } |
1235 | ||
1236 | /* Record that COND is true and INVERTED is false into the edge information | |
1237 | structure. Also record that any conditions dominated by COND are true | |
1238 | as well. | |
043d0665 | 1239 | |
1240 | For example, if a < b is true, then a <= b must also be true. */ | |
1241 | ||
1242 | static void | |
2f0993e7 | 1243 | record_conditions (struct edge_info *edge_info, tree cond, tree inverted) |
043d0665 | 1244 | { |
2f0993e7 | 1245 | tree op0, op1; |
7aab1427 | 1246 | cond_equivalence c; |
2f0993e7 | 1247 | |
1248 | if (!COMPARISON_CLASS_P (cond)) | |
1249 | return; | |
1250 | ||
1251 | op0 = TREE_OPERAND (cond, 0); | |
1252 | op1 = TREE_OPERAND (cond, 1); | |
1253 | ||
043d0665 | 1254 | switch (TREE_CODE (cond)) |
1255 | { | |
1256 | case LT_EXPR: | |
043d0665 | 1257 | case GT_EXPR: |
c4124729 | 1258 | if (FLOAT_TYPE_P (TREE_TYPE (op0))) |
1259 | { | |
c4124729 | 1260 | build_and_record_new_cond (ORDERED_EXPR, op0, op1, |
7aab1427 | 1261 | &edge_info->cond_equivalences); |
c4124729 | 1262 | build_and_record_new_cond (LTGT_EXPR, op0, op1, |
7aab1427 | 1263 | &edge_info->cond_equivalences); |
c4124729 | 1264 | } |
1265 | ||
2f0993e7 | 1266 | build_and_record_new_cond ((TREE_CODE (cond) == LT_EXPR |
1267 | ? LE_EXPR : GE_EXPR), | |
7aab1427 | 1268 | op0, op1, &edge_info->cond_equivalences); |
2f0993e7 | 1269 | build_and_record_new_cond (NE_EXPR, op0, op1, |
7aab1427 | 1270 | &edge_info->cond_equivalences); |
043d0665 | 1271 | break; |
1272 | ||
1273 | case GE_EXPR: | |
1274 | case LE_EXPR: | |
c4124729 | 1275 | if (FLOAT_TYPE_P (TREE_TYPE (op0))) |
1276 | { | |
c4124729 | 1277 | build_and_record_new_cond (ORDERED_EXPR, op0, op1, |
7aab1427 | 1278 | &edge_info->cond_equivalences); |
c4124729 | 1279 | } |
043d0665 | 1280 | break; |
1281 | ||
1282 | case EQ_EXPR: | |
c4124729 | 1283 | if (FLOAT_TYPE_P (TREE_TYPE (op0))) |
1284 | { | |
c4124729 | 1285 | build_and_record_new_cond (ORDERED_EXPR, op0, op1, |
7aab1427 | 1286 | &edge_info->cond_equivalences); |
c4124729 | 1287 | } |
2f0993e7 | 1288 | build_and_record_new_cond (LE_EXPR, op0, op1, |
7aab1427 | 1289 | &edge_info->cond_equivalences); |
2f0993e7 | 1290 | build_and_record_new_cond (GE_EXPR, op0, op1, |
7aab1427 | 1291 | &edge_info->cond_equivalences); |
043d0665 | 1292 | break; |
1293 | ||
1294 | case UNORDERED_EXPR: | |
2f0993e7 | 1295 | build_and_record_new_cond (NE_EXPR, op0, op1, |
7aab1427 | 1296 | &edge_info->cond_equivalences); |
2f0993e7 | 1297 | build_and_record_new_cond (UNLE_EXPR, op0, op1, |
7aab1427 | 1298 | &edge_info->cond_equivalences); |
2f0993e7 | 1299 | build_and_record_new_cond (UNGE_EXPR, op0, op1, |
7aab1427 | 1300 | &edge_info->cond_equivalences); |
2f0993e7 | 1301 | build_and_record_new_cond (UNEQ_EXPR, op0, op1, |
7aab1427 | 1302 | &edge_info->cond_equivalences); |
2f0993e7 | 1303 | build_and_record_new_cond (UNLT_EXPR, op0, op1, |
7aab1427 | 1304 | &edge_info->cond_equivalences); |
2f0993e7 | 1305 | build_and_record_new_cond (UNGT_EXPR, op0, op1, |
7aab1427 | 1306 | &edge_info->cond_equivalences); |
043d0665 | 1307 | break; |
1308 | ||
1309 | case UNLT_EXPR: | |
043d0665 | 1310 | case UNGT_EXPR: |
2f0993e7 | 1311 | build_and_record_new_cond ((TREE_CODE (cond) == UNLT_EXPR |
1312 | ? UNLE_EXPR : UNGE_EXPR), | |
7aab1427 | 1313 | op0, op1, &edge_info->cond_equivalences); |
2f0993e7 | 1314 | build_and_record_new_cond (NE_EXPR, op0, op1, |
7aab1427 | 1315 | &edge_info->cond_equivalences); |
043d0665 | 1316 | break; |
1317 | ||
1318 | case UNEQ_EXPR: | |
2f0993e7 | 1319 | build_and_record_new_cond (UNLE_EXPR, op0, op1, |
7aab1427 | 1320 | &edge_info->cond_equivalences); |
2f0993e7 | 1321 | build_and_record_new_cond (UNGE_EXPR, op0, op1, |
7aab1427 | 1322 | &edge_info->cond_equivalences); |
043d0665 | 1323 | break; |
1324 | ||
1325 | case LTGT_EXPR: | |
2f0993e7 | 1326 | build_and_record_new_cond (NE_EXPR, op0, op1, |
7aab1427 | 1327 | &edge_info->cond_equivalences); |
2f0993e7 | 1328 | build_and_record_new_cond (ORDERED_EXPR, op0, op1, |
7aab1427 | 1329 | &edge_info->cond_equivalences); |
2f0993e7 | 1330 | break; |
043d0665 | 1331 | |
1332 | default: | |
1333 | break; | |
1334 | } | |
2f0993e7 | 1335 | |
1336 | /* Now store the original true and false conditions into the first | |
1337 | two slots. */ | |
7aab1427 | 1338 | initialize_expr_from_cond (cond, &c.cond); |
1339 | c.value = boolean_true_node; | |
f1f41a6c | 1340 | edge_info->cond_equivalences.safe_push (c); |
75a70cf9 | 1341 | |
1342 | /* It is possible for INVERTED to be the negation of a comparison, | |
1343 | and not a valid RHS or GIMPLE_COND condition. This happens because | |
1344 | invert_truthvalue may return such an expression when asked to invert | |
1345 | a floating-point comparison. These comparisons are not assumed to | |
1346 | obey the trichotomy law. */ | |
7aab1427 | 1347 | initialize_expr_from_cond (inverted, &c.cond); |
1348 | c.value = boolean_false_node; | |
f1f41a6c | 1349 | edge_info->cond_equivalences.safe_push (c); |
043d0665 | 1350 | } |
1351 | ||
4ee9c684 | 1352 | /* A helper function for record_const_or_copy and record_equality. |
1353 | Do the work of recording the value and undo info. */ | |
1354 | ||
1355 | static void | |
da43203c | 1356 | record_const_or_copy_1 (tree x, tree y, tree prev_x) |
4ee9c684 | 1357 | { |
f003f9fd | 1358 | set_ssa_name_value (x, y); |
4ee9c684 | 1359 | |
75a70cf9 | 1360 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1361 | { | |
1362 | fprintf (dump_file, "0>>> COPY "); | |
1363 | print_generic_expr (dump_file, x, 0); | |
1364 | fprintf (dump_file, " = "); | |
1365 | print_generic_expr (dump_file, y, 0); | |
1366 | fprintf (dump_file, "\n"); | |
1367 | } | |
1368 | ||
f1f41a6c | 1369 | const_and_copies_stack.reserve (2); |
1370 | const_and_copies_stack.quick_push (prev_x); | |
1371 | const_and_copies_stack.quick_push (x); | |
4ee9c684 | 1372 | } |
1373 | ||
ba4c299c | 1374 | /* Return the loop depth of the basic block of the defining statement of X. |
1375 | This number should not be treated as absolutely correct because the loop | |
1376 | information may not be completely up-to-date when dom runs. However, it | |
1377 | will be relatively correct, and as more passes are taught to keep loop info | |
1378 | up to date, the result will become more and more accurate. */ | |
1379 | ||
88dbf20f | 1380 | int |
ba4c299c | 1381 | loop_depth_of_name (tree x) |
1382 | { | |
75a70cf9 | 1383 | gimple defstmt; |
ba4c299c | 1384 | basic_block defbb; |
1385 | ||
1386 | /* If it's not an SSA_NAME, we have no clue where the definition is. */ | |
1387 | if (TREE_CODE (x) != SSA_NAME) | |
1388 | return 0; | |
1389 | ||
1390 | /* Otherwise return the loop depth of the defining statement's bb. | |
1391 | Note that there may not actually be a bb for this statement, if the | |
1392 | ssa_name is live on entry. */ | |
1393 | defstmt = SSA_NAME_DEF_STMT (x); | |
75a70cf9 | 1394 | defbb = gimple_bb (defstmt); |
ba4c299c | 1395 | if (!defbb) |
1396 | return 0; | |
1397 | ||
6b42039a | 1398 | return bb_loop_depth (defbb); |
ba4c299c | 1399 | } |
1400 | ||
4ee9c684 | 1401 | /* Record that X is equal to Y in const_and_copies. Record undo |
f0458177 | 1402 | information in the block-local vector. */ |
4ee9c684 | 1403 | |
1404 | static void | |
da43203c | 1405 | record_const_or_copy (tree x, tree y) |
4ee9c684 | 1406 | { |
4c7a0518 | 1407 | tree prev_x = SSA_NAME_VALUE (x); |
4ee9c684 | 1408 | |
75a70cf9 | 1409 | gcc_assert (TREE_CODE (x) == SSA_NAME); |
1410 | ||
4ee9c684 | 1411 | if (TREE_CODE (y) == SSA_NAME) |
1412 | { | |
4c7a0518 | 1413 | tree tmp = SSA_NAME_VALUE (y); |
4ee9c684 | 1414 | if (tmp) |
1415 | y = tmp; | |
1416 | } | |
1417 | ||
da43203c | 1418 | record_const_or_copy_1 (x, y, prev_x); |
4ee9c684 | 1419 | } |
1420 | ||
1421 | /* Similarly, but assume that X and Y are the two operands of an EQ_EXPR. | |
1422 | This constrains the cases in which we may treat this as assignment. */ | |
1423 | ||
1424 | static void | |
da43203c | 1425 | record_equality (tree x, tree y) |
4ee9c684 | 1426 | { |
1427 | tree prev_x = NULL, prev_y = NULL; | |
1428 | ||
1429 | if (TREE_CODE (x) == SSA_NAME) | |
4c7a0518 | 1430 | prev_x = SSA_NAME_VALUE (x); |
4ee9c684 | 1431 | if (TREE_CODE (y) == SSA_NAME) |
4c7a0518 | 1432 | prev_y = SSA_NAME_VALUE (y); |
4ee9c684 | 1433 | |
ba4c299c | 1434 | /* If one of the previous values is invariant, or invariant in more loops |
1435 | (by depth), then use that. | |
4ee9c684 | 1436 | Otherwise it doesn't matter which value we choose, just so |
1437 | long as we canonicalize on one value. */ | |
71d9af81 | 1438 | if (is_gimple_min_invariant (y)) |
4ee9c684 | 1439 | ; |
71d9af81 | 1440 | else if (is_gimple_min_invariant (x) |
1441 | || (loop_depth_of_name (x) <= loop_depth_of_name (y))) | |
4ee9c684 | 1442 | prev_x = x, x = y, y = prev_x, prev_x = prev_y; |
71d9af81 | 1443 | else if (prev_x && is_gimple_min_invariant (prev_x)) |
4ee9c684 | 1444 | x = y, y = prev_x, prev_x = prev_y; |
f6c33c78 | 1445 | else if (prev_y) |
4ee9c684 | 1446 | y = prev_y; |
1447 | ||
1448 | /* After the swapping, we must have one SSA_NAME. */ | |
1449 | if (TREE_CODE (x) != SSA_NAME) | |
1450 | return; | |
1451 | ||
1452 | /* For IEEE, -0.0 == 0.0, so we don't necessarily know the sign of a | |
1453 | variable compared against zero. If we're honoring signed zeros, | |
1454 | then we cannot record this value unless we know that the value is | |
365db11e | 1455 | nonzero. */ |
4ee9c684 | 1456 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (x))) |
1457 | && (TREE_CODE (y) != REAL_CST | |
1458 | || REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (y)))) | |
1459 | return; | |
1460 | ||
da43203c | 1461 | record_const_or_copy_1 (x, y, prev_x); |
4ee9c684 | 1462 | } |
1463 | ||
119a0489 | 1464 | /* Returns true when STMT is a simple iv increment. It detects the |
1465 | following situation: | |
48e1416a | 1466 | |
119a0489 | 1467 | i_1 = phi (..., i_2) |
1468 | i_2 = i_1 +/- ... */ | |
1469 | ||
cd22a796 | 1470 | bool |
75a70cf9 | 1471 | simple_iv_increment_p (gimple stmt) |
119a0489 | 1472 | { |
cd22a796 | 1473 | enum tree_code code; |
75a70cf9 | 1474 | tree lhs, preinc; |
1475 | gimple phi; | |
1476 | size_t i; | |
119a0489 | 1477 | |
75a70cf9 | 1478 | if (gimple_code (stmt) != GIMPLE_ASSIGN) |
119a0489 | 1479 | return false; |
1480 | ||
75a70cf9 | 1481 | lhs = gimple_assign_lhs (stmt); |
119a0489 | 1482 | if (TREE_CODE (lhs) != SSA_NAME) |
1483 | return false; | |
1484 | ||
cd22a796 | 1485 | code = gimple_assign_rhs_code (stmt); |
1486 | if (code != PLUS_EXPR | |
1487 | && code != MINUS_EXPR | |
1488 | && code != POINTER_PLUS_EXPR) | |
119a0489 | 1489 | return false; |
1490 | ||
75a70cf9 | 1491 | preinc = gimple_assign_rhs1 (stmt); |
119a0489 | 1492 | if (TREE_CODE (preinc) != SSA_NAME) |
1493 | return false; | |
1494 | ||
1495 | phi = SSA_NAME_DEF_STMT (preinc); | |
75a70cf9 | 1496 | if (gimple_code (phi) != GIMPLE_PHI) |
119a0489 | 1497 | return false; |
1498 | ||
75a70cf9 | 1499 | for (i = 0; i < gimple_phi_num_args (phi); i++) |
1500 | if (gimple_phi_arg_def (phi, i) == lhs) | |
119a0489 | 1501 | return true; |
1502 | ||
1503 | return false; | |
1504 | } | |
1505 | ||
591c2a30 | 1506 | /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current |
48e1416a | 1507 | known value for that SSA_NAME (or NULL if no value is known). |
591c2a30 | 1508 | |
8dbf774a | 1509 | Propagate values from CONST_AND_COPIES into the PHI nodes of the |
1510 | successors of BB. */ | |
591c2a30 | 1511 | |
1512 | static void | |
8dbf774a | 1513 | cprop_into_successor_phis (basic_block bb) |
591c2a30 | 1514 | { |
1515 | edge e; | |
cd665a06 | 1516 | edge_iterator ei; |
591c2a30 | 1517 | |
cd665a06 | 1518 | FOR_EACH_EDGE (e, ei, bb->succs) |
591c2a30 | 1519 | { |
5f50f9bf | 1520 | int indx; |
75a70cf9 | 1521 | gimple_stmt_iterator gsi; |
591c2a30 | 1522 | |
1523 | /* If this is an abnormal edge, then we do not want to copy propagate | |
1524 | into the PHI alternative associated with this edge. */ | |
1525 | if (e->flags & EDGE_ABNORMAL) | |
1526 | continue; | |
1527 | ||
75a70cf9 | 1528 | gsi = gsi_start_phis (e->dest); |
1529 | if (gsi_end_p (gsi)) | |
591c2a30 | 1530 | continue; |
1531 | ||
5f50f9bf | 1532 | indx = e->dest_idx; |
75a70cf9 | 1533 | for ( ; !gsi_end_p (gsi); gsi_next (&gsi)) |
591c2a30 | 1534 | { |
f0d6e81c | 1535 | tree new_val; |
591c2a30 | 1536 | use_operand_p orig_p; |
f0d6e81c | 1537 | tree orig_val; |
75a70cf9 | 1538 | gimple phi = gsi_stmt (gsi); |
591c2a30 | 1539 | |
591c2a30 | 1540 | /* The alternative may be associated with a constant, so verify |
1541 | it is an SSA_NAME before doing anything with it. */ | |
75a70cf9 | 1542 | orig_p = gimple_phi_arg_imm_use_ptr (phi, indx); |
1543 | orig_val = get_use_from_ptr (orig_p); | |
f0d6e81c | 1544 | if (TREE_CODE (orig_val) != SSA_NAME) |
591c2a30 | 1545 | continue; |
1546 | ||
591c2a30 | 1547 | /* If we have *ORIG_P in our constant/copy table, then replace |
1548 | ORIG_P with its value in our constant/copy table. */ | |
f0d6e81c | 1549 | new_val = SSA_NAME_VALUE (orig_val); |
1550 | if (new_val | |
1551 | && new_val != orig_val | |
1552 | && (TREE_CODE (new_val) == SSA_NAME | |
1553 | || is_gimple_min_invariant (new_val)) | |
1554 | && may_propagate_copy (orig_val, new_val)) | |
1555 | propagate_value (orig_p, new_val); | |
591c2a30 | 1556 | } |
1557 | } | |
1558 | } | |
1559 | ||
2f0993e7 | 1560 | /* We have finished optimizing BB, record any information implied by |
1561 | taking a specific outgoing edge from BB. */ | |
1562 | ||
1563 | static void | |
1564 | record_edge_info (basic_block bb) | |
1565 | { | |
75a70cf9 | 1566 | gimple_stmt_iterator gsi = gsi_last_bb (bb); |
2f0993e7 | 1567 | struct edge_info *edge_info; |
1568 | ||
75a70cf9 | 1569 | if (! gsi_end_p (gsi)) |
2f0993e7 | 1570 | { |
75a70cf9 | 1571 | gimple stmt = gsi_stmt (gsi); |
389dd41b | 1572 | location_t loc = gimple_location (stmt); |
2f0993e7 | 1573 | |
75a70cf9 | 1574 | if (gimple_code (stmt) == GIMPLE_SWITCH) |
2f0993e7 | 1575 | { |
75a70cf9 | 1576 | tree index = gimple_switch_index (stmt); |
2f0993e7 | 1577 | |
75a70cf9 | 1578 | if (TREE_CODE (index) == SSA_NAME) |
2f0993e7 | 1579 | { |
75a70cf9 | 1580 | int i; |
1581 | int n_labels = gimple_switch_num_labels (stmt); | |
945865c5 | 1582 | tree *info = XCNEWVEC (tree, last_basic_block); |
2f0993e7 | 1583 | edge e; |
1584 | edge_iterator ei; | |
1585 | ||
1586 | for (i = 0; i < n_labels; i++) | |
1587 | { | |
75a70cf9 | 1588 | tree label = gimple_switch_label (stmt, i); |
2f0993e7 | 1589 | basic_block target_bb = label_to_block (CASE_LABEL (label)); |
2f0993e7 | 1590 | if (CASE_HIGH (label) |
1591 | || !CASE_LOW (label) | |
1592 | || info[target_bb->index]) | |
1593 | info[target_bb->index] = error_mark_node; | |
1594 | else | |
1595 | info[target_bb->index] = label; | |
1596 | } | |
1597 | ||
1598 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1599 | { | |
1600 | basic_block target_bb = e->dest; | |
75a70cf9 | 1601 | tree label = info[target_bb->index]; |
591c2a30 | 1602 | |
75a70cf9 | 1603 | if (label != NULL && label != error_mark_node) |
2f0993e7 | 1604 | { |
389dd41b | 1605 | tree x = fold_convert_loc (loc, TREE_TYPE (index), |
1606 | CASE_LOW (label)); | |
2f0993e7 | 1607 | edge_info = allocate_edge_info (e); |
75a70cf9 | 1608 | edge_info->lhs = index; |
2f0993e7 | 1609 | edge_info->rhs = x; |
1610 | } | |
1611 | } | |
1612 | free (info); | |
1613 | } | |
1614 | } | |
1615 | ||
1616 | /* A COND_EXPR may create equivalences too. */ | |
75a70cf9 | 1617 | if (gimple_code (stmt) == GIMPLE_COND) |
2f0993e7 | 1618 | { |
2f0993e7 | 1619 | edge true_edge; |
1620 | edge false_edge; | |
1621 | ||
75a70cf9 | 1622 | tree op0 = gimple_cond_lhs (stmt); |
1623 | tree op1 = gimple_cond_rhs (stmt); | |
1624 | enum tree_code code = gimple_cond_code (stmt); | |
2f0993e7 | 1625 | |
75a70cf9 | 1626 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); |
2f0993e7 | 1627 | |
75a70cf9 | 1628 | /* Special case comparing booleans against a constant as we |
1629 | know the value of OP0 on both arms of the branch. i.e., we | |
1630 | can record an equivalence for OP0 rather than COND. */ | |
1631 | if ((code == EQ_EXPR || code == NE_EXPR) | |
1632 | && TREE_CODE (op0) == SSA_NAME | |
1633 | && TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE | |
1634 | && is_gimple_min_invariant (op1)) | |
1635 | { | |
1636 | if (code == EQ_EXPR) | |
1637 | { | |
1638 | edge_info = allocate_edge_info (true_edge); | |
1639 | edge_info->lhs = op0; | |
1640 | edge_info->rhs = (integer_zerop (op1) | |
1641 | ? boolean_false_node | |
1642 | : boolean_true_node); | |
1643 | ||
1644 | edge_info = allocate_edge_info (false_edge); | |
1645 | edge_info->lhs = op0; | |
1646 | edge_info->rhs = (integer_zerop (op1) | |
1647 | ? boolean_true_node | |
1648 | : boolean_false_node); | |
1649 | } | |
1650 | else | |
1651 | { | |
1652 | edge_info = allocate_edge_info (true_edge); | |
1653 | edge_info->lhs = op0; | |
1654 | edge_info->rhs = (integer_zerop (op1) | |
1655 | ? boolean_true_node | |
1656 | : boolean_false_node); | |
1657 | ||
1658 | edge_info = allocate_edge_info (false_edge); | |
1659 | edge_info->lhs = op0; | |
1660 | edge_info->rhs = (integer_zerop (op1) | |
1661 | ? boolean_false_node | |
1662 | : boolean_true_node); | |
1663 | } | |
1664 | } | |
1665 | else if (is_gimple_min_invariant (op0) | |
1666 | && (TREE_CODE (op1) == SSA_NAME | |
1667 | || is_gimple_min_invariant (op1))) | |
1668 | { | |
1669 | tree cond = build2 (code, boolean_type_node, op0, op1); | |
389dd41b | 1670 | tree inverted = invert_truthvalue_loc (loc, cond); |
7b56081a | 1671 | bool can_infer_simple_equiv |
1672 | = !(HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op0))) | |
1673 | && real_zerop (op0)); | |
75a70cf9 | 1674 | struct edge_info *edge_info; |
1675 | ||
1676 | edge_info = allocate_edge_info (true_edge); | |
1677 | record_conditions (edge_info, cond, inverted); | |
1678 | ||
7b56081a | 1679 | if (can_infer_simple_equiv && code == EQ_EXPR) |
75a70cf9 | 1680 | { |
1681 | edge_info->lhs = op1; | |
1682 | edge_info->rhs = op0; | |
1683 | } | |
1684 | ||
1685 | edge_info = allocate_edge_info (false_edge); | |
1686 | record_conditions (edge_info, inverted, cond); | |
1687 | ||
7b56081a | 1688 | if (can_infer_simple_equiv && TREE_CODE (inverted) == EQ_EXPR) |
75a70cf9 | 1689 | { |
1690 | edge_info->lhs = op1; | |
1691 | edge_info->rhs = op0; | |
1692 | } | |
1693 | } | |
1694 | ||
1695 | else if (TREE_CODE (op0) == SSA_NAME | |
7b56081a | 1696 | && (TREE_CODE (op1) == SSA_NAME |
1697 | || is_gimple_min_invariant (op1))) | |
75a70cf9 | 1698 | { |
1699 | tree cond = build2 (code, boolean_type_node, op0, op1); | |
389dd41b | 1700 | tree inverted = invert_truthvalue_loc (loc, cond); |
7b56081a | 1701 | bool can_infer_simple_equiv |
1702 | = !(HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op1))) | |
1703 | && (TREE_CODE (op1) == SSA_NAME || real_zerop (op1))); | |
75a70cf9 | 1704 | struct edge_info *edge_info; |
1705 | ||
1706 | edge_info = allocate_edge_info (true_edge); | |
1707 | record_conditions (edge_info, cond, inverted); | |
1708 | ||
7b56081a | 1709 | if (can_infer_simple_equiv && code == EQ_EXPR) |
75a70cf9 | 1710 | { |
1711 | edge_info->lhs = op0; | |
1712 | edge_info->rhs = op1; | |
1713 | } | |
1714 | ||
1715 | edge_info = allocate_edge_info (false_edge); | |
1716 | record_conditions (edge_info, inverted, cond); | |
1717 | ||
7b56081a | 1718 | if (can_infer_simple_equiv && TREE_CODE (inverted) == EQ_EXPR) |
75a70cf9 | 1719 | { |
1720 | edge_info->lhs = op0; | |
1721 | edge_info->rhs = op1; | |
1722 | } | |
1723 | } | |
1724 | } | |
1725 | ||
1726 | /* ??? TRUTH_NOT_EXPR can create an equivalence too. */ | |
2f0993e7 | 1727 | } |
1728 | } | |
1729 | ||
4ee9c684 | 1730 | static void |
6bf320fb | 1731 | dom_opt_enter_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, |
1732 | basic_block bb) | |
4ee9c684 | 1733 | { |
6bf320fb | 1734 | gimple_stmt_iterator gsi; |
1735 | ||
1736 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1737 | fprintf (dump_file, "\n\nOptimizing block #%d\n\n", bb->index); | |
1738 | ||
1739 | /* Push a marker on the stacks of local information so that we know how | |
1740 | far to unwind when we finalize this block. */ | |
f1f41a6c | 1741 | avail_exprs_stack.safe_push (NULL); |
1742 | const_and_copies_stack.safe_push (NULL_TREE); | |
6bf320fb | 1743 | |
1744 | record_equivalences_from_incoming_edge (bb); | |
1745 | ||
1746 | /* PHI nodes can create equivalences too. */ | |
1747 | record_equivalences_from_phis (bb); | |
1748 | ||
889ef038 | 1749 | /* Create equivalences from redundant PHIs. PHIs are only truly |
1750 | redundant when they exist in the same block, so push another | |
1751 | marker and unwind right afterwards. */ | |
f1f41a6c | 1752 | avail_exprs_stack.safe_push (NULL); |
889ef038 | 1753 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
1754 | eliminate_redundant_computations (&gsi); | |
1755 | remove_local_expressions_from_table (); | |
1756 | ||
6bf320fb | 1757 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
1758 | optimize_stmt (bb, gsi); | |
1759 | ||
1760 | /* Now prepare to process dominated blocks. */ | |
2f0993e7 | 1761 | record_edge_info (bb); |
8dbf774a | 1762 | cprop_into_successor_phis (bb); |
4ee9c684 | 1763 | } |
1764 | ||
6bf320fb | 1765 | /* We have finished processing the dominator children of BB, perform |
1766 | any finalization actions in preparation for leaving this node in | |
1767 | the dominator tree. */ | |
1768 | ||
1769 | static void | |
1770 | dom_opt_leave_block (struct dom_walk_data *walk_data, basic_block bb) | |
1771 | { | |
1772 | gimple last; | |
1773 | ||
1774 | /* If we have an outgoing edge to a block with multiple incoming and | |
1775 | outgoing edges, then we may be able to thread the edge, i.e., we | |
1776 | may be able to statically determine which of the outgoing edges | |
1777 | will be traversed when the incoming edge from BB is traversed. */ | |
1778 | if (single_succ_p (bb) | |
1779 | && (single_succ_edge (bb)->flags & EDGE_ABNORMAL) == 0 | |
1780 | && potentially_threadable_block (single_succ (bb))) | |
1781 | { | |
9f396eaf | 1782 | /* Push a marker on the stack, which thread_across_edge expects |
1783 | and will remove. */ | |
f1f41a6c | 1784 | const_and_copies_stack.safe_push (NULL_TREE); |
6bf320fb | 1785 | dom_thread_across_edge (walk_data, single_succ_edge (bb)); |
1786 | } | |
1787 | else if ((last = last_stmt (bb)) | |
1788 | && gimple_code (last) == GIMPLE_COND | |
1789 | && EDGE_COUNT (bb->succs) == 2 | |
1790 | && (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) == 0 | |
1791 | && (EDGE_SUCC (bb, 1)->flags & EDGE_ABNORMAL) == 0) | |
1792 | { | |
1793 | edge true_edge, false_edge; | |
1794 | ||
1795 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
1796 | ||
1797 | /* Only try to thread the edge if it reaches a target block with | |
1798 | more than one predecessor and more than one successor. */ | |
1799 | if (potentially_threadable_block (true_edge->dest)) | |
1800 | { | |
1801 | struct edge_info *edge_info; | |
1802 | unsigned int i; | |
1803 | ||
1804 | /* Push a marker onto the available expression stack so that we | |
1805 | unwind any expressions related to the TRUE arm before processing | |
1806 | the false arm below. */ | |
f1f41a6c | 1807 | avail_exprs_stack.safe_push (NULL); |
1808 | const_and_copies_stack.safe_push (NULL_TREE); | |
6bf320fb | 1809 | |
1810 | edge_info = (struct edge_info *) true_edge->aux; | |
1811 | ||
1812 | /* If we have info associated with this edge, record it into | |
1813 | our equivalence tables. */ | |
1814 | if (edge_info) | |
1815 | { | |
7aab1427 | 1816 | cond_equivalence *eq; |
6bf320fb | 1817 | tree lhs = edge_info->lhs; |
1818 | tree rhs = edge_info->rhs; | |
1819 | ||
1820 | /* If we have a simple NAME = VALUE equivalence, record it. */ | |
1821 | if (lhs && TREE_CODE (lhs) == SSA_NAME) | |
1822 | record_const_or_copy (lhs, rhs); | |
1823 | ||
1824 | /* If we have 0 = COND or 1 = COND equivalences, record them | |
1825 | into our expression hash tables. */ | |
f1f41a6c | 1826 | for (i = 0; edge_info->cond_equivalences.iterate (i, &eq); ++i) |
7aab1427 | 1827 | record_cond (eq); |
6bf320fb | 1828 | } |
1829 | ||
1830 | dom_thread_across_edge (walk_data, true_edge); | |
1831 | ||
1832 | /* And restore the various tables to their state before | |
1833 | we threaded this edge. */ | |
1834 | remove_local_expressions_from_table (); | |
1835 | } | |
1836 | ||
1837 | /* Similarly for the ELSE arm. */ | |
1838 | if (potentially_threadable_block (false_edge->dest)) | |
1839 | { | |
1840 | struct edge_info *edge_info; | |
1841 | unsigned int i; | |
1842 | ||
f1f41a6c | 1843 | const_and_copies_stack.safe_push (NULL_TREE); |
6bf320fb | 1844 | edge_info = (struct edge_info *) false_edge->aux; |
1845 | ||
1846 | /* If we have info associated with this edge, record it into | |
1847 | our equivalence tables. */ | |
1848 | if (edge_info) | |
1849 | { | |
7aab1427 | 1850 | cond_equivalence *eq; |
6bf320fb | 1851 | tree lhs = edge_info->lhs; |
1852 | tree rhs = edge_info->rhs; | |
1853 | ||
1854 | /* If we have a simple NAME = VALUE equivalence, record it. */ | |
1855 | if (lhs && TREE_CODE (lhs) == SSA_NAME) | |
1856 | record_const_or_copy (lhs, rhs); | |
1857 | ||
1858 | /* If we have 0 = COND or 1 = COND equivalences, record them | |
1859 | into our expression hash tables. */ | |
f1f41a6c | 1860 | for (i = 0; edge_info->cond_equivalences.iterate (i, &eq); ++i) |
7aab1427 | 1861 | record_cond (eq); |
6bf320fb | 1862 | } |
1863 | ||
1864 | /* Now thread the edge. */ | |
1865 | dom_thread_across_edge (walk_data, false_edge); | |
1866 | ||
1867 | /* No need to remove local expressions from our tables | |
1868 | or restore vars to their original value as that will | |
1869 | be done immediately below. */ | |
1870 | } | |
1871 | } | |
1872 | ||
1873 | remove_local_expressions_from_table (); | |
1874 | restore_vars_to_original_value (); | |
6bf320fb | 1875 | } |
1876 | ||
4ee9c684 | 1877 | /* Search for redundant computations in STMT. If any are found, then |
1878 | replace them with the variable holding the result of the computation. | |
1879 | ||
1880 | If safe, record this expression into the available expression hash | |
1881 | table. */ | |
1882 | ||
e08ff65a | 1883 | static void |
75a70cf9 | 1884 | eliminate_redundant_computations (gimple_stmt_iterator* gsi) |
4ee9c684 | 1885 | { |
75a70cf9 | 1886 | tree expr_type; |
4ee9c684 | 1887 | tree cached_lhs; |
889ef038 | 1888 | tree def; |
75a70cf9 | 1889 | bool insert = true; |
75a70cf9 | 1890 | bool assigns_var_p = false; |
4ee9c684 | 1891 | |
75a70cf9 | 1892 | gimple stmt = gsi_stmt (*gsi); |
1893 | ||
889ef038 | 1894 | if (gimple_code (stmt) == GIMPLE_PHI) |
1895 | def = gimple_phi_result (stmt); | |
1896 | else | |
1897 | def = gimple_get_lhs (stmt); | |
4ee9c684 | 1898 | |
1899 | /* Certain expressions on the RHS can be optimized away, but can not | |
dac49aa5 | 1900 | themselves be entered into the hash tables. */ |
9d637cc5 | 1901 | if (! def |
4ee9c684 | 1902 | || TREE_CODE (def) != SSA_NAME |
1903 | || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def) | |
dd277d48 | 1904 | || gimple_vdef (stmt) |
119a0489 | 1905 | /* Do not record equivalences for increments of ivs. This would create |
1906 | overlapping live ranges for a very questionable gain. */ | |
1907 | || simple_iv_increment_p (stmt)) | |
4ee9c684 | 1908 | insert = false; |
1909 | ||
1910 | /* Check if the expression has been computed before. */ | |
9c629f0e | 1911 | cached_lhs = lookup_avail_expr (stmt, insert); |
4ee9c684 | 1912 | |
4ee9c684 | 1913 | opt_stats.num_exprs_considered++; |
1914 | ||
75a70cf9 | 1915 | /* Get the type of the expression we are trying to optimize. */ |
1916 | if (is_gimple_assign (stmt)) | |
f6be5aa5 | 1917 | { |
75a70cf9 | 1918 | expr_type = TREE_TYPE (gimple_assign_lhs (stmt)); |
1919 | assigns_var_p = true; | |
f6be5aa5 | 1920 | } |
75a70cf9 | 1921 | else if (gimple_code (stmt) == GIMPLE_COND) |
1922 | expr_type = boolean_type_node; | |
1923 | else if (is_gimple_call (stmt)) | |
f6be5aa5 | 1924 | { |
75a70cf9 | 1925 | gcc_assert (gimple_call_lhs (stmt)); |
1926 | expr_type = TREE_TYPE (gimple_call_lhs (stmt)); | |
1927 | assigns_var_p = true; | |
f6be5aa5 | 1928 | } |
75a70cf9 | 1929 | else if (gimple_code (stmt) == GIMPLE_SWITCH) |
1930 | expr_type = TREE_TYPE (gimple_switch_index (stmt)); | |
889ef038 | 1931 | else if (gimple_code (stmt) == GIMPLE_PHI) |
1932 | /* We can't propagate into a phi, so the logic below doesn't apply. | |
1933 | Instead record an equivalence between the cached LHS and the | |
1934 | PHI result of this statement, provided they are in the same block. | |
1935 | This should be sufficient to kill the redundant phi. */ | |
1936 | { | |
1937 | if (def && cached_lhs) | |
1938 | record_const_or_copy (def, cached_lhs); | |
1939 | return; | |
1940 | } | |
75a70cf9 | 1941 | else |
1942 | gcc_unreachable (); | |
1943 | ||
1944 | if (!cached_lhs) | |
e08ff65a | 1945 | return; |
4ee9c684 | 1946 | |
1947 | /* It is safe to ignore types here since we have already done | |
1948 | type checking in the hashing and equality routines. In fact | |
1949 | type checking here merely gets in the way of constant | |
1950 | propagation. Also, make sure that it is safe to propagate | |
75a70cf9 | 1951 | CACHED_LHS into the expression in STMT. */ |
1952 | if ((TREE_CODE (cached_lhs) != SSA_NAME | |
1953 | && (assigns_var_p | |
1954 | || useless_type_conversion_p (expr_type, TREE_TYPE (cached_lhs)))) | |
1955 | || may_propagate_copy_into_stmt (stmt, cached_lhs)) | |
1956 | { | |
1b4345f7 | 1957 | gcc_checking_assert (TREE_CODE (cached_lhs) == SSA_NAME |
1958 | || is_gimple_min_invariant (cached_lhs)); | |
75a70cf9 | 1959 | |
4ee9c684 | 1960 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1961 | { | |
1962 | fprintf (dump_file, " Replaced redundant expr '"); | |
75a70cf9 | 1963 | print_gimple_expr (dump_file, stmt, 0, dump_flags); |
4ee9c684 | 1964 | fprintf (dump_file, "' with '"); |
1965 | print_generic_expr (dump_file, cached_lhs, dump_flags); | |
75a70cf9 | 1966 | fprintf (dump_file, "'\n"); |
4ee9c684 | 1967 | } |
1968 | ||
1969 | opt_stats.num_re++; | |
48e1416a | 1970 | |
75a70cf9 | 1971 | if (assigns_var_p |
1972 | && !useless_type_conversion_p (expr_type, TREE_TYPE (cached_lhs))) | |
1973 | cached_lhs = fold_convert (expr_type, cached_lhs); | |
4ee9c684 | 1974 | |
75a70cf9 | 1975 | propagate_tree_value_into_stmt (gsi, cached_lhs); |
1976 | ||
1977 | /* Since it is always necessary to mark the result as modified, | |
1978 | perhaps we should move this into propagate_tree_value_into_stmt | |
1979 | itself. */ | |
1980 | gimple_set_modified (gsi_stmt (*gsi), true); | |
1981 | } | |
4ee9c684 | 1982 | } |
1983 | ||
75a70cf9 | 1984 | /* STMT, a GIMPLE_ASSIGN, may create certain equivalences, in either |
4ee9c684 | 1985 | the available expressions table or the const_and_copies table. |
1986 | Detect and record those equivalences. */ | |
75a70cf9 | 1987 | /* We handle only very simple copy equivalences here. The heavy |
1988 | lifing is done by eliminate_redundant_computations. */ | |
4ee9c684 | 1989 | |
1990 | static void | |
75a70cf9 | 1991 | record_equivalences_from_stmt (gimple stmt, int may_optimize_p) |
4ee9c684 | 1992 | { |
75a70cf9 | 1993 | tree lhs; |
1994 | enum tree_code lhs_code; | |
4ee9c684 | 1995 | |
75a70cf9 | 1996 | gcc_assert (is_gimple_assign (stmt)); |
1997 | ||
1998 | lhs = gimple_assign_lhs (stmt); | |
1999 | lhs_code = TREE_CODE (lhs); | |
4ee9c684 | 2000 | |
75a70cf9 | 2001 | if (lhs_code == SSA_NAME |
912886f2 | 2002 | && gimple_assign_single_p (stmt)) |
75a70cf9 | 2003 | { |
2004 | tree rhs = gimple_assign_rhs1 (stmt); | |
48e1416a | 2005 | |
4ee9c684 | 2006 | /* If the RHS of the assignment is a constant or another variable that |
2007 | may be propagated, register it in the CONST_AND_COPIES table. We | |
2008 | do not need to record unwind data for this, since this is a true | |
365db11e | 2009 | assignment and not an equivalence inferred from a comparison. All |
4ee9c684 | 2010 | uses of this ssa name are dominated by this assignment, so unwinding |
2011 | just costs time and space. */ | |
2012 | if (may_optimize_p | |
2013 | && (TREE_CODE (rhs) == SSA_NAME | |
2014 | || is_gimple_min_invariant (rhs))) | |
75a70cf9 | 2015 | { |
2016 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2017 | { | |
2018 | fprintf (dump_file, "==== ASGN "); | |
2019 | print_generic_expr (dump_file, lhs, 0); | |
2020 | fprintf (dump_file, " = "); | |
2021 | print_generic_expr (dump_file, rhs, 0); | |
2022 | fprintf (dump_file, "\n"); | |
2023 | } | |
2024 | ||
f003f9fd | 2025 | set_ssa_name_value (lhs, rhs); |
75a70cf9 | 2026 | } |
4ee9c684 | 2027 | } |
2028 | ||
4ee9c684 | 2029 | /* A memory store, even an aliased store, creates a useful |
2030 | equivalence. By exchanging the LHS and RHS, creating suitable | |
2031 | vops and recording the result in the available expression table, | |
2032 | we may be able to expose more redundant loads. */ | |
75a70cf9 | 2033 | if (!gimple_has_volatile_ops (stmt) |
2034 | && gimple_references_memory_p (stmt) | |
2035 | && gimple_assign_single_p (stmt) | |
2036 | && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME | |
2037 | || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))) | |
4ee9c684 | 2038 | && !is_gimple_reg (lhs)) |
2039 | { | |
75a70cf9 | 2040 | tree rhs = gimple_assign_rhs1 (stmt); |
2041 | gimple new_stmt; | |
4ee9c684 | 2042 | |
e607210a | 2043 | /* Build a new statement with the RHS and LHS exchanged. */ |
75a70cf9 | 2044 | if (TREE_CODE (rhs) == SSA_NAME) |
2045 | { | |
2046 | /* NOTE tuples. The call to gimple_build_assign below replaced | |
2047 | a call to build_gimple_modify_stmt, which did not set the | |
2048 | SSA_NAME_DEF_STMT on the LHS of the assignment. Doing so | |
2049 | may cause an SSA validation failure, as the LHS may be a | |
2050 | default-initialized name and should have no definition. I'm | |
2051 | a bit dubious of this, as the artificial statement that we | |
2052 | generate here may in fact be ill-formed, but it is simply | |
2053 | used as an internal device in this pass, and never becomes | |
2054 | part of the CFG. */ | |
2055 | gimple defstmt = SSA_NAME_DEF_STMT (rhs); | |
2056 | new_stmt = gimple_build_assign (rhs, lhs); | |
2057 | SSA_NAME_DEF_STMT (rhs) = defstmt; | |
2058 | } | |
2059 | else | |
2060 | new_stmt = gimple_build_assign (rhs, lhs); | |
2061 | ||
dd277d48 | 2062 | gimple_set_vuse (new_stmt, gimple_vdef (stmt)); |
4ee9c684 | 2063 | |
e607210a | 2064 | /* Finally enter the statement into the available expression |
2065 | table. */ | |
2066 | lookup_avail_expr (new_stmt, true); | |
4ee9c684 | 2067 | } |
2068 | } | |
2069 | ||
591c2a30 | 2070 | /* Replace *OP_P in STMT with any known equivalent value for *OP_P from |
2071 | CONST_AND_COPIES. */ | |
2072 | ||
e08ff65a | 2073 | static void |
75a70cf9 | 2074 | cprop_operand (gimple stmt, use_operand_p op_p) |
591c2a30 | 2075 | { |
591c2a30 | 2076 | tree val; |
2077 | tree op = USE_FROM_PTR (op_p); | |
2078 | ||
2079 | /* If the operand has a known constant value or it is known to be a | |
2080 | copy of some other variable, use the value or copy stored in | |
2081 | CONST_AND_COPIES. */ | |
4c7a0518 | 2082 | val = SSA_NAME_VALUE (op); |
f6c33c78 | 2083 | if (val && val != op) |
591c2a30 | 2084 | { |
93b4f514 | 2085 | /* Do not replace hard register operands in asm statements. */ |
75a70cf9 | 2086 | if (gimple_code (stmt) == GIMPLE_ASM |
93b4f514 | 2087 | && !may_propagate_copy_into_asm (op)) |
e08ff65a | 2088 | return; |
93b4f514 | 2089 | |
591c2a30 | 2090 | /* Certain operands are not allowed to be copy propagated due |
2091 | to their interaction with exception handling and some GCC | |
2092 | extensions. */ | |
93f3673b | 2093 | if (!may_propagate_copy (op, val)) |
e08ff65a | 2094 | return; |
93f3673b | 2095 | |
2096 | /* Do not propagate addresses that point to volatiles into memory | |
2097 | stmts without volatile operands. */ | |
2098 | if (POINTER_TYPE_P (TREE_TYPE (val)) | |
2099 | && TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (val))) | |
2100 | && gimple_has_mem_ops (stmt) | |
2101 | && !gimple_has_volatile_ops (stmt)) | |
e08ff65a | 2102 | return; |
93f3673b | 2103 | |
652a5bec | 2104 | /* Do not propagate copies if the propagated value is at a deeper loop |
2105 | depth than the propagatee. Otherwise, this may move loop variant | |
2106 | variables outside of their loops and prevent coalescing | |
2107 | opportunities. If the value was loop invariant, it will be hoisted | |
2108 | by LICM and exposed for copy propagation. */ | |
2109 | if (loop_depth_of_name (val) > loop_depth_of_name (op)) | |
e08ff65a | 2110 | return; |
591c2a30 | 2111 | |
09d0041c | 2112 | /* Do not propagate copies into simple IV increment statements. |
2113 | See PR23821 for how this can disturb IV analysis. */ | |
2114 | if (TREE_CODE (val) != INTEGER_CST | |
2115 | && simple_iv_increment_p (stmt)) | |
2116 | return; | |
2117 | ||
591c2a30 | 2118 | /* Dump details. */ |
2119 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2120 | { | |
2121 | fprintf (dump_file, " Replaced '"); | |
2122 | print_generic_expr (dump_file, op, dump_flags); | |
2123 | fprintf (dump_file, "' with %s '", | |
2124 | (TREE_CODE (val) != SSA_NAME ? "constant" : "variable")); | |
2125 | print_generic_expr (dump_file, val, dump_flags); | |
2126 | fprintf (dump_file, "'\n"); | |
2127 | } | |
2128 | ||
88dbf20f | 2129 | if (TREE_CODE (val) != SSA_NAME) |
2130 | opt_stats.num_const_prop++; | |
2131 | else | |
2132 | opt_stats.num_copy_prop++; | |
2133 | ||
591c2a30 | 2134 | propagate_value (op_p, val); |
2135 | ||
2136 | /* And note that we modified this statement. This is now | |
2137 | safe, even if we changed virtual operands since we will | |
2138 | rescan the statement and rewrite its operands again. */ | |
75a70cf9 | 2139 | gimple_set_modified (stmt, true); |
591c2a30 | 2140 | } |
591c2a30 | 2141 | } |
2142 | ||
2143 | /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current | |
48e1416a | 2144 | known value for that SSA_NAME (or NULL if no value is known). |
591c2a30 | 2145 | |
2146 | Propagate values from CONST_AND_COPIES into the uses, vuses and | |
de6ed584 | 2147 | vdef_ops of STMT. */ |
591c2a30 | 2148 | |
e08ff65a | 2149 | static void |
75a70cf9 | 2150 | cprop_into_stmt (gimple stmt) |
591c2a30 | 2151 | { |
43daa21e | 2152 | use_operand_p op_p; |
2153 | ssa_op_iter iter; | |
591c2a30 | 2154 | |
8bf038d5 | 2155 | FOR_EACH_SSA_USE_OPERAND (op_p, stmt, iter, SSA_OP_USE) |
2156 | cprop_operand (stmt, op_p); | |
591c2a30 | 2157 | } |
2158 | ||
5206b159 | 2159 | /* Optimize the statement pointed to by iterator SI. |
48e1416a | 2160 | |
4ee9c684 | 2161 | We try to perform some simplistic global redundancy elimination and |
2162 | constant propagation: | |
2163 | ||
2164 | 1- To detect global redundancy, we keep track of expressions that have | |
2165 | been computed in this block and its dominators. If we find that the | |
2166 | same expression is computed more than once, we eliminate repeated | |
2167 | computations by using the target of the first one. | |
2168 | ||
2169 | 2- Constant values and copy assignments. This is used to do very | |
2170 | simplistic constant and copy propagation. When a constant or copy | |
2171 | assignment is found, we map the value on the RHS of the assignment to | |
2172 | the variable in the LHS in the CONST_AND_COPIES table. */ | |
2173 | ||
2174 | static void | |
6bf320fb | 2175 | optimize_stmt (basic_block bb, gimple_stmt_iterator si) |
4ee9c684 | 2176 | { |
75a70cf9 | 2177 | gimple stmt, old_stmt; |
4ee9c684 | 2178 | bool may_optimize_p; |
c8c258fe | 2179 | bool modified_p = false; |
4ee9c684 | 2180 | |
75a70cf9 | 2181 | old_stmt = stmt = gsi_stmt (si); |
48e1416a | 2182 | |
4ee9c684 | 2183 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2184 | { | |
2185 | fprintf (dump_file, "Optimizing statement "); | |
75a70cf9 | 2186 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
4ee9c684 | 2187 | } |
2188 | ||
8bf038d5 | 2189 | if (gimple_code (stmt) == GIMPLE_COND) |
2190 | canonicalize_comparison (stmt); | |
2191 | ||
2192 | update_stmt_if_modified (stmt); | |
2193 | opt_stats.num_stmts++; | |
2194 | ||
de6ed584 | 2195 | /* Const/copy propagate into USES, VUSES and the RHS of VDEFs. */ |
e08ff65a | 2196 | cprop_into_stmt (stmt); |
4ee9c684 | 2197 | |
2198 | /* If the statement has been modified with constant replacements, | |
2199 | fold its RHS before checking for redundant computations. */ | |
75a70cf9 | 2200 | if (gimple_modified_p (stmt)) |
4ee9c684 | 2201 | { |
75a70cf9 | 2202 | tree rhs = NULL; |
f2fae51f | 2203 | |
4ee9c684 | 2204 | /* Try to fold the statement making sure that STMT is kept |
2205 | up to date. */ | |
75a70cf9 | 2206 | if (fold_stmt (&si)) |
4ee9c684 | 2207 | { |
75a70cf9 | 2208 | stmt = gsi_stmt (si); |
7548e9fe | 2209 | gimple_set_modified (stmt, true); |
4ee9c684 | 2210 | |
2211 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2212 | { | |
2213 | fprintf (dump_file, " Folded to: "); | |
75a70cf9 | 2214 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
4ee9c684 | 2215 | } |
2216 | } | |
2217 | ||
75a70cf9 | 2218 | /* We only need to consider cases that can yield a gimple operand. */ |
2219 | if (gimple_assign_single_p (stmt)) | |
2220 | rhs = gimple_assign_rhs1 (stmt); | |
2221 | else if (gimple_code (stmt) == GIMPLE_GOTO) | |
2222 | rhs = gimple_goto_dest (stmt); | |
2223 | else if (gimple_code (stmt) == GIMPLE_SWITCH) | |
2224 | /* This should never be an ADDR_EXPR. */ | |
2225 | rhs = gimple_switch_index (stmt); | |
2226 | ||
f2fae51f | 2227 | if (rhs && TREE_CODE (rhs) == ADDR_EXPR) |
75a70cf9 | 2228 | recompute_tree_invariant_for_addr_expr (rhs); |
f2fae51f | 2229 | |
c8c258fe | 2230 | /* Indicate that maybe_clean_or_replace_eh_stmt needs to be called, |
2231 | even if fold_stmt updated the stmt already and thus cleared | |
2232 | gimple_modified_p flag on it. */ | |
2233 | modified_p = true; | |
4ee9c684 | 2234 | } |
2235 | ||
2236 | /* Check for redundant computations. Do this optimization only | |
2237 | for assignments that have no volatile ops and conditionals. */ | |
f1960495 | 2238 | may_optimize_p = (!gimple_has_side_effects (stmt) |
2239 | && (is_gimple_assign (stmt) | |
75a70cf9 | 2240 | || (is_gimple_call (stmt) |
f1960495 | 2241 | && gimple_call_lhs (stmt) != NULL_TREE) |
75a70cf9 | 2242 | || gimple_code (stmt) == GIMPLE_COND |
2243 | || gimple_code (stmt) == GIMPLE_SWITCH)); | |
4ee9c684 | 2244 | |
2245 | if (may_optimize_p) | |
75a70cf9 | 2246 | { |
a65c4d64 | 2247 | if (gimple_code (stmt) == GIMPLE_CALL) |
2248 | { | |
2249 | /* Resolve __builtin_constant_p. If it hasn't been | |
2250 | folded to integer_one_node by now, it's fairly | |
2251 | certain that the value simply isn't constant. */ | |
2252 | tree callee = gimple_call_fndecl (stmt); | |
2253 | if (callee | |
2254 | && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL | |
2255 | && DECL_FUNCTION_CODE (callee) == BUILT_IN_CONSTANT_P) | |
2256 | { | |
2257 | propagate_tree_value_into_stmt (&si, integer_zero_node); | |
2258 | stmt = gsi_stmt (si); | |
2259 | } | |
2260 | } | |
04c3b49f | 2261 | |
2262 | update_stmt_if_modified (stmt); | |
2263 | eliminate_redundant_computations (&si); | |
2264 | stmt = gsi_stmt (si); | |
31047158 | 2265 | |
2266 | /* Perform simple redundant store elimination. */ | |
2267 | if (gimple_assign_single_p (stmt) | |
2268 | && TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME) | |
2269 | { | |
2270 | tree lhs = gimple_assign_lhs (stmt); | |
2271 | tree rhs = gimple_assign_rhs1 (stmt); | |
2272 | tree cached_lhs; | |
2273 | gimple new_stmt; | |
2274 | if (TREE_CODE (rhs) == SSA_NAME) | |
2275 | { | |
2276 | tree tem = SSA_NAME_VALUE (rhs); | |
2277 | if (tem) | |
2278 | rhs = tem; | |
2279 | } | |
2280 | /* Build a new statement with the RHS and LHS exchanged. */ | |
2281 | if (TREE_CODE (rhs) == SSA_NAME) | |
2282 | { | |
2283 | gimple defstmt = SSA_NAME_DEF_STMT (rhs); | |
2284 | new_stmt = gimple_build_assign (rhs, lhs); | |
2285 | SSA_NAME_DEF_STMT (rhs) = defstmt; | |
2286 | } | |
2287 | else | |
2288 | new_stmt = gimple_build_assign (rhs, lhs); | |
2289 | gimple_set_vuse (new_stmt, gimple_vuse (stmt)); | |
2290 | cached_lhs = lookup_avail_expr (new_stmt, false); | |
2291 | if (cached_lhs | |
2292 | && rhs == cached_lhs) | |
2293 | { | |
2294 | basic_block bb = gimple_bb (stmt); | |
31047158 | 2295 | unlink_stmt_vdef (stmt); |
13ff78a4 | 2296 | if (gsi_remove (&si, true)) |
31047158 | 2297 | { |
2298 | bitmap_set_bit (need_eh_cleanup, bb->index); | |
2299 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2300 | fprintf (dump_file, " Flagged to clear EH edges.\n"); | |
2301 | } | |
bc8a8451 | 2302 | release_defs (stmt); |
31047158 | 2303 | return; |
2304 | } | |
2305 | } | |
75a70cf9 | 2306 | } |
4ee9c684 | 2307 | |
2308 | /* Record any additional equivalences created by this statement. */ | |
75a70cf9 | 2309 | if (is_gimple_assign (stmt)) |
2310 | record_equivalences_from_stmt (stmt, may_optimize_p); | |
4ee9c684 | 2311 | |
4ee9c684 | 2312 | /* If STMT is a COND_EXPR and it was modified, then we may know |
2313 | where it goes. If that is the case, then mark the CFG as altered. | |
2314 | ||
2315 | This will cause us to later call remove_unreachable_blocks and | |
48e1416a | 2316 | cleanup_tree_cfg when it is safe to do so. It is not safe to |
4ee9c684 | 2317 | clean things up here since removal of edges and such can trigger |
2318 | the removal of PHI nodes, which in turn can release SSA_NAMEs to | |
2319 | the manager. | |
2320 | ||
2321 | That's all fine and good, except that once SSA_NAMEs are released | |
2322 | to the manager, we must not call create_ssa_name until all references | |
2323 | to released SSA_NAMEs have been eliminated. | |
2324 | ||
2325 | All references to the deleted SSA_NAMEs can not be eliminated until | |
2326 | we remove unreachable blocks. | |
2327 | ||
2328 | We can not remove unreachable blocks until after we have completed | |
2329 | any queued jump threading. | |
2330 | ||
2331 | We can not complete any queued jump threads until we have taken | |
2332 | appropriate variables out of SSA form. Taking variables out of | |
2333 | SSA form can call create_ssa_name and thus we lose. | |
2334 | ||
2335 | Ultimately I suspect we're going to need to change the interface | |
2336 | into the SSA_NAME manager. */ | |
c8c258fe | 2337 | if (gimple_modified_p (stmt) || modified_p) |
4ee9c684 | 2338 | { |
2339 | tree val = NULL; | |
48e1416a | 2340 | |
04c3b49f | 2341 | update_stmt_if_modified (stmt); |
4ee9c684 | 2342 | |
75a70cf9 | 2343 | if (gimple_code (stmt) == GIMPLE_COND) |
389dd41b | 2344 | val = fold_binary_loc (gimple_location (stmt), |
2345 | gimple_cond_code (stmt), boolean_type_node, | |
75a70cf9 | 2346 | gimple_cond_lhs (stmt), gimple_cond_rhs (stmt)); |
2347 | else if (gimple_code (stmt) == GIMPLE_SWITCH) | |
2348 | val = gimple_switch_index (stmt); | |
4ee9c684 | 2349 | |
35c15734 | 2350 | if (val && TREE_CODE (val) == INTEGER_CST && find_taken_edge (bb, val)) |
4ee9c684 | 2351 | cfg_altered = true; |
35c15734 | 2352 | |
2353 | /* If we simplified a statement in such a way as to be shown that it | |
2354 | cannot trap, update the eh information and the cfg to match. */ | |
4c27dd45 | 2355 | if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)) |
35c15734 | 2356 | { |
2357 | bitmap_set_bit (need_eh_cleanup, bb->index); | |
2358 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2359 | fprintf (dump_file, " Flagged to clear EH edges.\n"); | |
2360 | } | |
4ee9c684 | 2361 | } |
4ee9c684 | 2362 | } |
2363 | ||
75a70cf9 | 2364 | /* Search for an existing instance of STMT in the AVAIL_EXPRS table. |
2365 | If found, return its LHS. Otherwise insert STMT in the table and | |
2366 | return NULL_TREE. | |
4ee9c684 | 2367 | |
75a70cf9 | 2368 | Also, when an expression is first inserted in the table, it is also |
2369 | is also added to AVAIL_EXPRS_STACK, so that it can be removed when | |
2370 | we finish processing this block and its children. */ | |
4ee9c684 | 2371 | |
2372 | static tree | |
75a70cf9 | 2373 | lookup_avail_expr (gimple stmt, bool insert) |
4ee9c684 | 2374 | { |
2375 | void **slot; | |
2376 | tree lhs; | |
2377 | tree temp; | |
88006128 | 2378 | struct expr_hash_elt element; |
4ee9c684 | 2379 | |
889ef038 | 2380 | /* Get LHS of phi, assignment, or call; else NULL_TREE. */ |
2381 | if (gimple_code (stmt) == GIMPLE_PHI) | |
2382 | lhs = gimple_phi_result (stmt); | |
2383 | else | |
2384 | lhs = gimple_get_lhs (stmt); | |
4ee9c684 | 2385 | |
88006128 | 2386 | initialize_hash_element (stmt, lhs, &element); |
4ee9c684 | 2387 | |
75a70cf9 | 2388 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2389 | { | |
2390 | fprintf (dump_file, "LKUP "); | |
88006128 | 2391 | print_expr_hash_elt (dump_file, &element); |
75a70cf9 | 2392 | } |
2393 | ||
4ee9c684 | 2394 | /* Don't bother remembering constant assignments and copy operations. |
2395 | Constants and copy operations are handled by the constant/copy propagator | |
2396 | in optimize_stmt. */ | |
88006128 | 2397 | if (element.expr.kind == EXPR_SINGLE |
2398 | && (TREE_CODE (element.expr.ops.single.rhs) == SSA_NAME | |
2399 | || is_gimple_min_invariant (element.expr.ops.single.rhs))) | |
2400 | return NULL_TREE; | |
4ee9c684 | 2401 | |
4ee9c684 | 2402 | /* Finally try to find the expression in the main expression hash table. */ |
88006128 | 2403 | slot = htab_find_slot_with_hash (avail_exprs, &element, element.hash, |
4ee9c684 | 2404 | (insert ? INSERT : NO_INSERT)); |
2405 | if (slot == NULL) | |
78d53e33 | 2406 | { |
2407 | free_expr_hash_elt_contents (&element); | |
2408 | return NULL_TREE; | |
2409 | } | |
2410 | else if (*slot == NULL) | |
4ee9c684 | 2411 | { |
88006128 | 2412 | struct expr_hash_elt *element2 = XNEW (struct expr_hash_elt); |
2413 | *element2 = element; | |
2414 | element2->stamp = element2; | |
2415 | *slot = (void *) element2; | |
75a70cf9 | 2416 | |
2417 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2418 | { | |
2419 | fprintf (dump_file, "2>>> "); | |
88006128 | 2420 | print_expr_hash_elt (dump_file, element2); |
75a70cf9 | 2421 | } |
2422 | ||
f1f41a6c | 2423 | avail_exprs_stack.safe_push (element2); |
4ee9c684 | 2424 | return NULL_TREE; |
2425 | } | |
78d53e33 | 2426 | else |
2427 | free_expr_hash_elt_contents (&element); | |
4ee9c684 | 2428 | |
2429 | /* Extract the LHS of the assignment so that it can be used as the current | |
2430 | definition of another variable. */ | |
2431 | lhs = ((struct expr_hash_elt *)*slot)->lhs; | |
2432 | ||
2433 | /* See if the LHS appears in the CONST_AND_COPIES table. If it does, then | |
2434 | use the value from the const_and_copies table. */ | |
2435 | if (TREE_CODE (lhs) == SSA_NAME) | |
2436 | { | |
4c7a0518 | 2437 | temp = SSA_NAME_VALUE (lhs); |
f6c33c78 | 2438 | if (temp) |
4ee9c684 | 2439 | lhs = temp; |
2440 | } | |
2441 | ||
75a70cf9 | 2442 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2443 | { | |
2444 | fprintf (dump_file, "FIND: "); | |
2445 | print_generic_expr (dump_file, lhs, 0); | |
2446 | fprintf (dump_file, "\n"); | |
2447 | } | |
2448 | ||
4ee9c684 | 2449 | return lhs; |
2450 | } | |
2451 | ||
75a70cf9 | 2452 | /* Hashing and equality functions for AVAIL_EXPRS. We compute a value number |
2453 | for expressions using the code of the expression and the SSA numbers of | |
2454 | its operands. */ | |
4ee9c684 | 2455 | |
2456 | static hashval_t | |
2457 | avail_expr_hash (const void *p) | |
2458 | { | |
75a70cf9 | 2459 | gimple stmt = ((const struct expr_hash_elt *)p)->stmt; |
2460 | const struct hashable_expr *expr = &((const struct expr_hash_elt *)p)->expr; | |
b66731e8 | 2461 | tree vuse; |
4ee9c684 | 2462 | hashval_t val = 0; |
4ee9c684 | 2463 | |
75a70cf9 | 2464 | val = iterative_hash_hashable_expr (expr, val); |
4ee9c684 | 2465 | |
2466 | /* If the hash table entry is not associated with a statement, then we | |
2467 | can just hash the expression and not worry about virtual operands | |
2468 | and such. */ | |
75a70cf9 | 2469 | if (!stmt) |
4ee9c684 | 2470 | return val; |
2471 | ||
dd277d48 | 2472 | /* Add the SSA version numbers of the vuse operand. This is important |
4ee9c684 | 2473 | because compound variables like arrays are not renamed in the |
2474 | operands. Rather, the rename is done on the virtual variable | |
2475 | representing all the elements of the array. */ | |
dd277d48 | 2476 | if ((vuse = gimple_vuse (stmt))) |
b66731e8 | 2477 | val = iterative_hash_expr (vuse, val); |
4ee9c684 | 2478 | |
2479 | return val; | |
2480 | } | |
2481 | ||
23ace16d | 2482 | static hashval_t |
2483 | real_avail_expr_hash (const void *p) | |
2484 | { | |
2485 | return ((const struct expr_hash_elt *)p)->hash; | |
2486 | } | |
4ee9c684 | 2487 | |
2488 | static int | |
2489 | avail_expr_eq (const void *p1, const void *p2) | |
2490 | { | |
75a70cf9 | 2491 | gimple stmt1 = ((const struct expr_hash_elt *)p1)->stmt; |
2492 | const struct hashable_expr *expr1 = &((const struct expr_hash_elt *)p1)->expr; | |
2493 | const struct expr_hash_elt *stamp1 = ((const struct expr_hash_elt *)p1)->stamp; | |
2494 | gimple stmt2 = ((const struct expr_hash_elt *)p2)->stmt; | |
2495 | const struct hashable_expr *expr2 = &((const struct expr_hash_elt *)p2)->expr; | |
2496 | const struct expr_hash_elt *stamp2 = ((const struct expr_hash_elt *)p2)->stamp; | |
2497 | ||
2498 | /* This case should apply only when removing entries from the table. */ | |
2499 | if (stamp1 == stamp2) | |
4ee9c684 | 2500 | return true; |
2501 | ||
75a70cf9 | 2502 | /* FIXME tuples: |
2503 | We add stmts to a hash table and them modify them. To detect the case | |
2504 | that we modify a stmt and then search for it, we assume that the hash | |
2505 | is always modified by that change. | |
2506 | We have to fully check why this doesn't happen on trunk or rewrite | |
2507 | this in a more reliable (and easier to understand) way. */ | |
2508 | if (((const struct expr_hash_elt *)p1)->hash | |
2509 | != ((const struct expr_hash_elt *)p2)->hash) | |
4ee9c684 | 2510 | return false; |
2511 | ||
2512 | /* In case of a collision, both RHS have to be identical and have the | |
2513 | same VUSE operands. */ | |
75a70cf9 | 2514 | if (hashable_expr_equal_p (expr1, expr2) |
2515 | && types_compatible_p (expr1->type, expr2->type)) | |
4ee9c684 | 2516 | { |
75a70cf9 | 2517 | /* Note that STMT1 and/or STMT2 may be NULL. */ |
dd277d48 | 2518 | return ((stmt1 ? gimple_vuse (stmt1) : NULL_TREE) |
2519 | == (stmt2 ? gimple_vuse (stmt2) : NULL_TREE)); | |
4ee9c684 | 2520 | } |
2521 | ||
2522 | return false; | |
2523 | } | |
d1d2af7d | 2524 | |
2525 | /* PHI-ONLY copy and constant propagation. This pass is meant to clean | |
2526 | up degenerate PHIs created by or exposed by jump threading. */ | |
2527 | ||
2528 | /* Given PHI, return its RHS if the PHI is a degenerate, otherwise return | |
2529 | NULL. */ | |
2530 | ||
ac9b13de | 2531 | tree |
75a70cf9 | 2532 | degenerate_phi_result (gimple phi) |
d1d2af7d | 2533 | { |
75a70cf9 | 2534 | tree lhs = gimple_phi_result (phi); |
d1d2af7d | 2535 | tree val = NULL; |
75a70cf9 | 2536 | size_t i; |
d1d2af7d | 2537 | |
2538 | /* Ignoring arguments which are the same as LHS, if all the remaining | |
2539 | arguments are the same, then the PHI is a degenerate and has the | |
2540 | value of that common argument. */ | |
75a70cf9 | 2541 | for (i = 0; i < gimple_phi_num_args (phi); i++) |
d1d2af7d | 2542 | { |
75a70cf9 | 2543 | tree arg = gimple_phi_arg_def (phi, i); |
d1d2af7d | 2544 | |
2545 | if (arg == lhs) | |
2546 | continue; | |
4eb376e3 | 2547 | else if (!arg) |
2548 | break; | |
d1d2af7d | 2549 | else if (!val) |
2550 | val = arg; | |
43e54ec3 | 2551 | else if (arg == val) |
2552 | continue; | |
2553 | /* We bring in some of operand_equal_p not only to speed things | |
2554 | up, but also to avoid crashing when dereferencing the type of | |
2555 | a released SSA name. */ | |
4eb376e3 | 2556 | else if (TREE_CODE (val) != TREE_CODE (arg) |
43e54ec3 | 2557 | || TREE_CODE (val) == SSA_NAME |
2558 | || !operand_equal_p (arg, val, 0)) | |
d1d2af7d | 2559 | break; |
2560 | } | |
75a70cf9 | 2561 | return (i == gimple_phi_num_args (phi) ? val : NULL); |
d1d2af7d | 2562 | } |
2563 | ||
75a70cf9 | 2564 | /* Given a statement STMT, which is either a PHI node or an assignment, |
d1d2af7d | 2565 | remove it from the IL. */ |
2566 | ||
2567 | static void | |
75a70cf9 | 2568 | remove_stmt_or_phi (gimple stmt) |
d1d2af7d | 2569 | { |
75a70cf9 | 2570 | gimple_stmt_iterator gsi = gsi_for_stmt (stmt); |
2571 | ||
2572 | if (gimple_code (stmt) == GIMPLE_PHI) | |
2573 | remove_phi_node (&gsi, true); | |
d1d2af7d | 2574 | else |
2575 | { | |
75a70cf9 | 2576 | gsi_remove (&gsi, true); |
2577 | release_defs (stmt); | |
d1d2af7d | 2578 | } |
2579 | } | |
2580 | ||
75a70cf9 | 2581 | /* Given a statement STMT, which is either a PHI node or an assignment, |
d1d2af7d | 2582 | return the "rhs" of the node, in the case of a non-degenerate |
75a70cf9 | 2583 | phi, NULL is returned. */ |
d1d2af7d | 2584 | |
2585 | static tree | |
75a70cf9 | 2586 | get_rhs_or_phi_arg (gimple stmt) |
d1d2af7d | 2587 | { |
75a70cf9 | 2588 | if (gimple_code (stmt) == GIMPLE_PHI) |
2589 | return degenerate_phi_result (stmt); | |
2590 | else if (gimple_assign_single_p (stmt)) | |
2591 | return gimple_assign_rhs1 (stmt); | |
2592 | else | |
2593 | gcc_unreachable (); | |
d1d2af7d | 2594 | } |
2595 | ||
2596 | ||
75a70cf9 | 2597 | /* Given a statement STMT, which is either a PHI node or an assignment, |
d1d2af7d | 2598 | return the "lhs" of the node. */ |
2599 | ||
2600 | static tree | |
75a70cf9 | 2601 | get_lhs_or_phi_result (gimple stmt) |
d1d2af7d | 2602 | { |
75a70cf9 | 2603 | if (gimple_code (stmt) == GIMPLE_PHI) |
2604 | return gimple_phi_result (stmt); | |
2605 | else if (is_gimple_assign (stmt)) | |
2606 | return gimple_assign_lhs (stmt); | |
2607 | else | |
2608 | gcc_unreachable (); | |
d1d2af7d | 2609 | } |
2610 | ||
2611 | /* Propagate RHS into all uses of LHS (when possible). | |
2612 | ||
2613 | RHS and LHS are derived from STMT, which is passed in solely so | |
2614 | that we can remove it if propagation is successful. | |
2615 | ||
2616 | When propagating into a PHI node or into a statement which turns | |
2617 | into a trivial copy or constant initialization, set the | |
2618 | appropriate bit in INTERESTING_NAMEs so that we will visit those | |
2619 | nodes as well in an effort to pick up secondary optimization | |
2620 | opportunities. */ | |
2621 | ||
48e1416a | 2622 | static void |
75a70cf9 | 2623 | propagate_rhs_into_lhs (gimple stmt, tree lhs, tree rhs, bitmap interesting_names) |
d1d2af7d | 2624 | { |
2625 | /* First verify that propagation is valid and isn't going to move a | |
2626 | loop variant variable outside its loop. */ | |
2627 | if (! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs) | |
2628 | && (TREE_CODE (rhs) != SSA_NAME | |
2629 | || ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs)) | |
2630 | && may_propagate_copy (lhs, rhs) | |
2631 | && loop_depth_of_name (lhs) >= loop_depth_of_name (rhs)) | |
2632 | { | |
2633 | use_operand_p use_p; | |
2634 | imm_use_iterator iter; | |
75a70cf9 | 2635 | gimple use_stmt; |
d1d2af7d | 2636 | bool all = true; |
2637 | ||
2638 | /* Dump details. */ | |
2639 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2640 | { | |
2641 | fprintf (dump_file, " Replacing '"); | |
2642 | print_generic_expr (dump_file, lhs, dump_flags); | |
2643 | fprintf (dump_file, "' with %s '", | |
2644 | (TREE_CODE (rhs) != SSA_NAME ? "constant" : "variable")); | |
2645 | print_generic_expr (dump_file, rhs, dump_flags); | |
2646 | fprintf (dump_file, "'\n"); | |
2647 | } | |
2648 | ||
48e1416a | 2649 | /* Walk over every use of LHS and try to replace the use with RHS. |
d1d2af7d | 2650 | At this point the only reason why such a propagation would not |
2651 | be successful would be if the use occurs in an ASM_EXPR. */ | |
09aca5bc | 2652 | FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs) |
d1d2af7d | 2653 | { |
9845d120 | 2654 | /* Leave debug stmts alone. If we succeed in propagating |
2655 | all non-debug uses, we'll drop the DEF, and propagation | |
2656 | into debug stmts will occur then. */ | |
2657 | if (gimple_debug_bind_p (use_stmt)) | |
2658 | continue; | |
48e1416a | 2659 | |
d1d2af7d | 2660 | /* It's not always safe to propagate into an ASM_EXPR. */ |
75a70cf9 | 2661 | if (gimple_code (use_stmt) == GIMPLE_ASM |
2662 | && ! may_propagate_copy_into_asm (lhs)) | |
d1d2af7d | 2663 | { |
2664 | all = false; | |
2665 | continue; | |
2666 | } | |
2667 | ||
ec396ca3 | 2668 | /* It's not ok to propagate into the definition stmt of RHS. |
2669 | <bb 9>: | |
2670 | # prephitmp.12_36 = PHI <g_67.1_6(9)> | |
2671 | g_67.1_6 = prephitmp.12_36; | |
2672 | goto <bb 9>; | |
2673 | While this is strictly all dead code we do not want to | |
2674 | deal with this here. */ | |
2675 | if (TREE_CODE (rhs) == SSA_NAME | |
2676 | && SSA_NAME_DEF_STMT (rhs) == use_stmt) | |
2677 | { | |
2678 | all = false; | |
2679 | continue; | |
2680 | } | |
2681 | ||
d1d2af7d | 2682 | /* Dump details. */ |
2683 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2684 | { | |
2685 | fprintf (dump_file, " Original statement:"); | |
75a70cf9 | 2686 | print_gimple_stmt (dump_file, use_stmt, 0, dump_flags); |
d1d2af7d | 2687 | } |
2688 | ||
d76551d9 | 2689 | /* Propagate the RHS into this use of the LHS. */ |
09aca5bc | 2690 | FOR_EACH_IMM_USE_ON_STMT (use_p, iter) |
2691 | propagate_value (use_p, rhs); | |
d76551d9 | 2692 | |
2693 | /* Special cases to avoid useless calls into the folding | |
2694 | routines, operand scanning, etc. | |
2695 | ||
7ecda5e8 | 2696 | Propagation into a PHI may cause the PHI to become |
d76551d9 | 2697 | a degenerate, so mark the PHI as interesting. No other |
7ecda5e8 | 2698 | actions are necessary. */ |
2699 | if (gimple_code (use_stmt) == GIMPLE_PHI) | |
d76551d9 | 2700 | { |
7ecda5e8 | 2701 | tree result; |
2702 | ||
d76551d9 | 2703 | /* Dump details. */ |
2704 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2705 | { | |
2706 | fprintf (dump_file, " Updated statement:"); | |
75a70cf9 | 2707 | print_gimple_stmt (dump_file, use_stmt, 0, dump_flags); |
d76551d9 | 2708 | } |
2709 | ||
7ecda5e8 | 2710 | result = get_lhs_or_phi_result (use_stmt); |
2711 | bitmap_set_bit (interesting_names, SSA_NAME_VERSION (result)); | |
d76551d9 | 2712 | continue; |
2713 | } | |
2714 | ||
48e1416a | 2715 | /* From this point onward we are propagating into a |
d76551d9 | 2716 | real statement. Folding may (or may not) be possible, |
2717 | we may expose new operands, expose dead EH edges, | |
2718 | etc. */ | |
75a70cf9 | 2719 | /* NOTE tuples. In the tuples world, fold_stmt_inplace |
2720 | cannot fold a call that simplifies to a constant, | |
2721 | because the GIMPLE_CALL must be replaced by a | |
2722 | GIMPLE_ASSIGN, and there is no way to effect such a | |
2723 | transformation in-place. We might want to consider | |
2724 | using the more general fold_stmt here. */ | |
50aacf4c | 2725 | { |
2726 | gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt); | |
2727 | fold_stmt_inplace (&gsi); | |
2728 | } | |
2f067d14 | 2729 | |
2730 | /* Sometimes propagation can expose new operands to the | |
4c5fd53c | 2731 | renamer. */ |
2732 | update_stmt (use_stmt); | |
d1d2af7d | 2733 | |
2734 | /* Dump details. */ | |
2735 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2736 | { | |
2737 | fprintf (dump_file, " Updated statement:"); | |
75a70cf9 | 2738 | print_gimple_stmt (dump_file, use_stmt, 0, dump_flags); |
d1d2af7d | 2739 | } |
2740 | ||
d1d2af7d | 2741 | /* If we replaced a variable index with a constant, then |
2742 | we would need to update the invariant flag for ADDR_EXPRs. */ | |
75a70cf9 | 2743 | if (gimple_assign_single_p (use_stmt) |
2744 | && TREE_CODE (gimple_assign_rhs1 (use_stmt)) == ADDR_EXPR) | |
35cc02b5 | 2745 | recompute_tree_invariant_for_addr_expr |
75a70cf9 | 2746 | (gimple_assign_rhs1 (use_stmt)); |
d1d2af7d | 2747 | |
2748 | /* If we cleaned up EH information from the statement, | |
d65e4929 | 2749 | mark its containing block as needing EH cleanups. */ |
d1d2af7d | 2750 | if (maybe_clean_or_replace_eh_stmt (use_stmt, use_stmt)) |
d65e4929 | 2751 | { |
75a70cf9 | 2752 | bitmap_set_bit (need_eh_cleanup, gimple_bb (use_stmt)->index); |
d65e4929 | 2753 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2754 | fprintf (dump_file, " Flagged to clear EH edges.\n"); | |
2755 | } | |
d1d2af7d | 2756 | |
d76551d9 | 2757 | /* Propagation may expose new trivial copy/constant propagation |
2758 | opportunities. */ | |
75a70cf9 | 2759 | if (gimple_assign_single_p (use_stmt) |
2760 | && TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME | |
2761 | && (TREE_CODE (gimple_assign_rhs1 (use_stmt)) == SSA_NAME | |
2762 | || is_gimple_min_invariant (gimple_assign_rhs1 (use_stmt)))) | |
2763 | { | |
d1d2af7d | 2764 | tree result = get_lhs_or_phi_result (use_stmt); |
2765 | bitmap_set_bit (interesting_names, SSA_NAME_VERSION (result)); | |
2766 | } | |
2767 | ||
2768 | /* Propagation into these nodes may make certain edges in | |
2769 | the CFG unexecutable. We want to identify them as PHI nodes | |
2770 | at the destination of those unexecutable edges may become | |
2771 | degenerates. */ | |
75a70cf9 | 2772 | else if (gimple_code (use_stmt) == GIMPLE_COND |
2773 | || gimple_code (use_stmt) == GIMPLE_SWITCH | |
2774 | || gimple_code (use_stmt) == GIMPLE_GOTO) | |
2775 | { | |
d1d2af7d | 2776 | tree val; |
2777 | ||
75a70cf9 | 2778 | if (gimple_code (use_stmt) == GIMPLE_COND) |
389dd41b | 2779 | val = fold_binary_loc (gimple_location (use_stmt), |
2780 | gimple_cond_code (use_stmt), | |
75a70cf9 | 2781 | boolean_type_node, |
2782 | gimple_cond_lhs (use_stmt), | |
2783 | gimple_cond_rhs (use_stmt)); | |
2784 | else if (gimple_code (use_stmt) == GIMPLE_SWITCH) | |
2785 | val = gimple_switch_index (use_stmt); | |
d1d2af7d | 2786 | else |
75a70cf9 | 2787 | val = gimple_goto_dest (use_stmt); |
d1d2af7d | 2788 | |
75a70cf9 | 2789 | if (val && is_gimple_min_invariant (val)) |
d1d2af7d | 2790 | { |
75a70cf9 | 2791 | basic_block bb = gimple_bb (use_stmt); |
d1d2af7d | 2792 | edge te = find_taken_edge (bb, val); |
2793 | edge_iterator ei; | |
2794 | edge e; | |
75a70cf9 | 2795 | gimple_stmt_iterator gsi, psi; |
d1d2af7d | 2796 | |
2797 | /* Remove all outgoing edges except TE. */ | |
2798 | for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei));) | |
2799 | { | |
2800 | if (e != te) | |
2801 | { | |
d1d2af7d | 2802 | /* Mark all the PHI nodes at the destination of |
2803 | the unexecutable edge as interesting. */ | |
75a70cf9 | 2804 | for (psi = gsi_start_phis (e->dest); |
2805 | !gsi_end_p (psi); | |
2806 | gsi_next (&psi)) | |
2807 | { | |
2808 | gimple phi = gsi_stmt (psi); | |
2809 | ||
2810 | tree result = gimple_phi_result (phi); | |
d1d2af7d | 2811 | int version = SSA_NAME_VERSION (result); |
2812 | ||
2813 | bitmap_set_bit (interesting_names, version); | |
2814 | } | |
2815 | ||
2816 | te->probability += e->probability; | |
2817 | ||
2818 | te->count += e->count; | |
2819 | remove_edge (e); | |
9a17dd7d | 2820 | cfg_altered = true; |
d1d2af7d | 2821 | } |
2822 | else | |
2823 | ei_next (&ei); | |
2824 | } | |
2825 | ||
75a70cf9 | 2826 | gsi = gsi_last_bb (gimple_bb (use_stmt)); |
2827 | gsi_remove (&gsi, true); | |
d1d2af7d | 2828 | |
2829 | /* And fixup the flags on the single remaining edge. */ | |
2830 | te->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); | |
2831 | te->flags &= ~EDGE_ABNORMAL; | |
2832 | te->flags |= EDGE_FALLTHRU; | |
2833 | if (te->probability > REG_BR_PROB_BASE) | |
2834 | te->probability = REG_BR_PROB_BASE; | |
2835 | } | |
2836 | } | |
2837 | } | |
2838 | ||
48e1416a | 2839 | /* Ensure there is nothing else to do. */ |
76e6653a | 2840 | gcc_assert (!all || has_zero_uses (lhs)); |
ea54ad41 | 2841 | |
d1d2af7d | 2842 | /* If we were able to propagate away all uses of LHS, then |
2843 | we can remove STMT. */ | |
2844 | if (all) | |
2845 | remove_stmt_or_phi (stmt); | |
2846 | } | |
2847 | } | |
2848 | ||
75a70cf9 | 2849 | /* STMT is either a PHI node (potentially a degenerate PHI node) or |
d1d2af7d | 2850 | a statement that is a trivial copy or constant initialization. |
2851 | ||
2852 | Attempt to eliminate T by propagating its RHS into all uses of | |
2853 | its LHS. This may in turn set new bits in INTERESTING_NAMES | |
2854 | for nodes we want to revisit later. | |
2855 | ||
2856 | All exit paths should clear INTERESTING_NAMES for the result | |
75a70cf9 | 2857 | of STMT. */ |
d1d2af7d | 2858 | |
2859 | static void | |
75a70cf9 | 2860 | eliminate_const_or_copy (gimple stmt, bitmap interesting_names) |
d1d2af7d | 2861 | { |
75a70cf9 | 2862 | tree lhs = get_lhs_or_phi_result (stmt); |
d1d2af7d | 2863 | tree rhs; |
2864 | int version = SSA_NAME_VERSION (lhs); | |
2865 | ||
2866 | /* If the LHS of this statement or PHI has no uses, then we can | |
2867 | just eliminate it. This can occur if, for example, the PHI | |
2868 | was created by block duplication due to threading and its only | |
2869 | use was in the conditional at the end of the block which was | |
2870 | deleted. */ | |
2871 | if (has_zero_uses (lhs)) | |
2872 | { | |
2873 | bitmap_clear_bit (interesting_names, version); | |
75a70cf9 | 2874 | remove_stmt_or_phi (stmt); |
d1d2af7d | 2875 | return; |
2876 | } | |
2877 | ||
2878 | /* Get the RHS of the assignment or PHI node if the PHI is a | |
2879 | degenerate. */ | |
75a70cf9 | 2880 | rhs = get_rhs_or_phi_arg (stmt); |
d1d2af7d | 2881 | if (!rhs) |
2882 | { | |
2883 | bitmap_clear_bit (interesting_names, version); | |
2884 | return; | |
2885 | } | |
2886 | ||
75a70cf9 | 2887 | propagate_rhs_into_lhs (stmt, lhs, rhs, interesting_names); |
d1d2af7d | 2888 | |
75a70cf9 | 2889 | /* Note that STMT may well have been deleted by now, so do |
d1d2af7d | 2890 | not access it, instead use the saved version # to clear |
2891 | T's entry in the worklist. */ | |
2892 | bitmap_clear_bit (interesting_names, version); | |
2893 | } | |
2894 | ||
2895 | /* The first phase in degenerate PHI elimination. | |
2896 | ||
2897 | Eliminate the degenerate PHIs in BB, then recurse on the | |
2898 | dominator children of BB. */ | |
2899 | ||
2900 | static void | |
2901 | eliminate_degenerate_phis_1 (basic_block bb, bitmap interesting_names) | |
2902 | { | |
75a70cf9 | 2903 | gimple_stmt_iterator gsi; |
d1d2af7d | 2904 | basic_block son; |
2905 | ||
75a70cf9 | 2906 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
d1d2af7d | 2907 | { |
75a70cf9 | 2908 | gimple phi = gsi_stmt (gsi); |
2909 | ||
d1d2af7d | 2910 | eliminate_const_or_copy (phi, interesting_names); |
2911 | } | |
2912 | ||
2913 | /* Recurse into the dominator children of BB. */ | |
2914 | for (son = first_dom_son (CDI_DOMINATORS, bb); | |
2915 | son; | |
2916 | son = next_dom_son (CDI_DOMINATORS, son)) | |
2917 | eliminate_degenerate_phis_1 (son, interesting_names); | |
2918 | } | |
2919 | ||
2920 | ||
2921 | /* A very simple pass to eliminate degenerate PHI nodes from the | |
2922 | IL. This is meant to be fast enough to be able to be run several | |
2923 | times in the optimization pipeline. | |
2924 | ||
2925 | Certain optimizations, particularly those which duplicate blocks | |
2926 | or remove edges from the CFG can create or expose PHIs which are | |
2927 | trivial copies or constant initializations. | |
2928 | ||
2929 | While we could pick up these optimizations in DOM or with the | |
2930 | combination of copy-prop and CCP, those solutions are far too | |
2931 | heavy-weight for our needs. | |
2932 | ||
2933 | This implementation has two phases so that we can efficiently | |
2934 | eliminate the first order degenerate PHIs and second order | |
2935 | degenerate PHIs. | |
2936 | ||
2937 | The first phase performs a dominator walk to identify and eliminate | |
2938 | the vast majority of the degenerate PHIs. When a degenerate PHI | |
2939 | is identified and eliminated any affected statements or PHIs | |
2940 | are put on a worklist. | |
2941 | ||
2942 | The second phase eliminates degenerate PHIs and trivial copies | |
2943 | or constant initializations using the worklist. This is how we | |
2944 | pick up the secondary optimization opportunities with minimal | |
2945 | cost. */ | |
2946 | ||
2947 | static unsigned int | |
2948 | eliminate_degenerate_phis (void) | |
2949 | { | |
2950 | bitmap interesting_names; | |
76af66a6 | 2951 | bitmap interesting_names1; |
d1d2af7d | 2952 | |
d65e4929 | 2953 | /* Bitmap of blocks which need EH information updated. We can not |
2954 | update it on-the-fly as doing so invalidates the dominator tree. */ | |
2955 | need_eh_cleanup = BITMAP_ALLOC (NULL); | |
2956 | ||
d1d2af7d | 2957 | /* INTERESTING_NAMES is effectively our worklist, indexed by |
2958 | SSA_NAME_VERSION. | |
2959 | ||
2960 | A set bit indicates that the statement or PHI node which | |
2961 | defines the SSA_NAME should be (re)examined to determine if | |
4562961a | 2962 | it has become a degenerate PHI or trivial const/copy propagation |
48e1416a | 2963 | opportunity. |
d1d2af7d | 2964 | |
2965 | Experiments have show we generally get better compilation | |
2966 | time behavior with bitmaps rather than sbitmaps. */ | |
2967 | interesting_names = BITMAP_ALLOC (NULL); | |
76af66a6 | 2968 | interesting_names1 = BITMAP_ALLOC (NULL); |
d1d2af7d | 2969 | |
9a17dd7d | 2970 | calculate_dominance_info (CDI_DOMINATORS); |
2971 | cfg_altered = false; | |
2972 | ||
9ca2c29a | 2973 | /* First phase. Eliminate degenerate PHIs via a dominator |
d1d2af7d | 2974 | walk of the CFG. |
2975 | ||
2976 | Experiments have indicated that we generally get better | |
2977 | compile-time behavior by visiting blocks in the first | |
2978 | phase in dominator order. Presumably this is because walking | |
2979 | in dominator order leaves fewer PHIs for later examination | |
2980 | by the worklist phase. */ | |
d1d2af7d | 2981 | eliminate_degenerate_phis_1 (ENTRY_BLOCK_PTR, interesting_names); |
2982 | ||
9ca2c29a | 2983 | /* Second phase. Eliminate second order degenerate PHIs as well |
d1d2af7d | 2984 | as trivial copies or constant initializations identified by |
2985 | the first phase or this phase. Basically we keep iterating | |
2986 | until our set of INTERESTING_NAMEs is empty. */ | |
2987 | while (!bitmap_empty_p (interesting_names)) | |
2988 | { | |
2989 | unsigned int i; | |
2990 | bitmap_iterator bi; | |
2991 | ||
76af66a6 | 2992 | /* EXECUTE_IF_SET_IN_BITMAP does not like its bitmap |
2993 | changed during the loop. Copy it to another bitmap and | |
2994 | use that. */ | |
2995 | bitmap_copy (interesting_names1, interesting_names); | |
2996 | ||
2997 | EXECUTE_IF_SET_IN_BITMAP (interesting_names1, 0, i, bi) | |
d1d2af7d | 2998 | { |
2999 | tree name = ssa_name (i); | |
3000 | ||
3001 | /* Ignore SSA_NAMEs that have been released because | |
3002 | their defining statement was deleted (unreachable). */ | |
3003 | if (name) | |
3004 | eliminate_const_or_copy (SSA_NAME_DEF_STMT (ssa_name (i)), | |
3005 | interesting_names); | |
3006 | } | |
3007 | } | |
d65e4929 | 3008 | |
9a17dd7d | 3009 | if (cfg_altered) |
3010 | free_dominance_info (CDI_DOMINATORS); | |
3011 | ||
d65e4929 | 3012 | /* Propagation of const and copies may make some EH edges dead. Purge |
3013 | such edges from the CFG as needed. */ | |
3014 | if (!bitmap_empty_p (need_eh_cleanup)) | |
3015 | { | |
75a70cf9 | 3016 | gimple_purge_all_dead_eh_edges (need_eh_cleanup); |
d65e4929 | 3017 | BITMAP_FREE (need_eh_cleanup); |
3018 | } | |
d1d2af7d | 3019 | |
3020 | BITMAP_FREE (interesting_names); | |
76af66a6 | 3021 | BITMAP_FREE (interesting_names1); |
d1d2af7d | 3022 | return 0; |
3023 | } | |
3024 | ||
20099e35 | 3025 | struct gimple_opt_pass pass_phi_only_cprop = |
d1d2af7d | 3026 | { |
20099e35 | 3027 | { |
3028 | GIMPLE_PASS, | |
d1d2af7d | 3029 | "phicprop", /* name */ |
c7875731 | 3030 | OPTGROUP_NONE, /* optinfo_flags */ |
d1d2af7d | 3031 | gate_dominator, /* gate */ |
3032 | eliminate_degenerate_phis, /* execute */ | |
3033 | NULL, /* sub */ | |
3034 | NULL, /* next */ | |
3035 | 0, /* static_pass_number */ | |
1ef27f86 | 3036 | TV_TREE_PHI_CPROP, /* tv_id */ |
2f8eb909 | 3037 | PROP_cfg | PROP_ssa, /* properties_required */ |
d1d2af7d | 3038 | 0, /* properties_provided */ |
b6246c40 | 3039 | 0, /* properties_destroyed */ |
d1d2af7d | 3040 | 0, /* todo_flags_start */ |
eb9161e7 | 3041 | TODO_cleanup_cfg |
eb9161e7 | 3042 | | TODO_ggc_collect |
3043 | | TODO_verify_ssa | |
3044 | | TODO_verify_stmts | |
20099e35 | 3045 | | TODO_update_ssa /* todo_flags_finish */ |
3046 | } | |
d1d2af7d | 3047 | }; |