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6de9cd9a DN |
1 | /* SSA Dominator optimizations for trees |
2 | Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc. | |
3 | Contributed by Diego Novillo <dnovillo@redhat.com> | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING. If not, write to | |
19 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
20 | Boston, MA 02111-1307, USA. */ | |
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" | |
28 | #include "rtl.h" | |
29 | #include "tm_p.h" | |
30 | #include "ggc.h" | |
31 | #include "basic-block.h" | |
32 | #include "output.h" | |
33 | #include "errors.h" | |
34 | #include "expr.h" | |
35 | #include "function.h" | |
36 | #include "diagnostic.h" | |
37 | #include "timevar.h" | |
38 | #include "tree-dump.h" | |
39 | #include "tree-flow.h" | |
40 | #include "domwalk.h" | |
41 | #include "real.h" | |
42 | #include "tree-pass.h" | |
c7f90219 | 43 | #include "tree-ssa-propagate.h" |
6de9cd9a DN |
44 | #include "langhooks.h" |
45 | ||
46 | /* This file implements optimizations on the dominator tree. */ | |
47 | ||
48 | /* Hash table with expressions made available during the renaming process. | |
49 | When an assignment of the form X_i = EXPR is found, the statement is | |
50 | stored in this table. If the same expression EXPR is later found on the | |
51 | RHS of another statement, it is replaced with X_i (thus performing | |
52 | global redundancy elimination). Similarly as we pass through conditionals | |
53 | we record the conditional itself as having either a true or false value | |
54 | in this table. */ | |
55 | static htab_t avail_exprs; | |
56 | ||
48732f23 JL |
57 | /* Stack of available expressions in AVAIL_EXPRs. Each block pushes any |
58 | expressions it enters into the hash table along with a marker entry | |
b3a27618 | 59 | (null). When we finish processing the block, we pop off entries and |
48732f23 JL |
60 | remove the expressions from the global hash table until we hit the |
61 | marker. */ | |
62 | static varray_type avail_exprs_stack; | |
63 | ||
9fae925b JL |
64 | /* Stack of trees used to restore the global currdefs to its original |
65 | state after completing optimization of a block and its dominator children. | |
66 | ||
67 | An SSA_NAME indicates that the current definition of the underlying | |
68 | variable should be set to the given SSA_NAME. | |
69 | ||
70 | A _DECL node indicates that the underlying variable has no current | |
71 | definition. | |
72 | ||
73 | A NULL node is used to mark the last node associated with the | |
74 | current block. */ | |
75 | varray_type block_defs_stack; | |
76 | ||
a6e1aa26 JL |
77 | /* Stack of statements we need to rescan during finalization for newly |
78 | exposed variables. | |
79 | ||
80 | Statement rescanning must occur after the current block's available | |
81 | expressions are removed from AVAIL_EXPRS. Else we may change the | |
82 | hash code for an expression and be unable to find/remove it from | |
83 | AVAIL_EXPRS. */ | |
84 | varray_type stmts_to_rescan; | |
85 | ||
6de9cd9a DN |
86 | /* Structure for entries in the expression hash table. |
87 | ||
88 | This requires more memory for the hash table entries, but allows us | |
89 | to avoid creating silly tree nodes and annotations for conditionals, | |
90 | eliminates 2 global hash tables and two block local varrays. | |
91 | ||
92 | It also allows us to reduce the number of hash table lookups we | |
93 | have to perform in lookup_avail_expr and finally it allows us to | |
94 | significantly reduce the number of calls into the hashing routine | |
95 | itself. */ | |
56b043c8 | 96 | |
6de9cd9a DN |
97 | struct expr_hash_elt |
98 | { | |
99 | /* The value (lhs) of this expression. */ | |
100 | tree lhs; | |
101 | ||
102 | /* The expression (rhs) we want to record. */ | |
103 | tree rhs; | |
104 | ||
105 | /* The annotation if this element corresponds to a statement. */ | |
106 | stmt_ann_t ann; | |
107 | ||
108 | /* The hash value for RHS/ann. */ | |
109 | hashval_t hash; | |
110 | }; | |
111 | ||
b5fefcf6 JL |
112 | /* Stack of dest,src pairs that need to be restored during finalization. |
113 | ||
114 | A NULL entry is used to mark the end of pairs which need to be | |
115 | restored during finalization of this block. */ | |
116 | static varray_type const_and_copies_stack; | |
117 | ||
6de9cd9a DN |
118 | /* Bitmap of SSA_NAMEs known to have a nonzero value, even if we do not |
119 | know their exact value. */ | |
120 | static bitmap nonzero_vars; | |
121 | ||
fdabe5c2 JL |
122 | /* Stack of SSA_NAMEs which need their NONZERO_VARS property cleared |
123 | when the current block is finalized. | |
124 | ||
125 | A NULL entry is used to mark the end of names needing their | |
126 | entry in NONZERO_VARS cleared during finalization of this block. */ | |
127 | static varray_type nonzero_vars_stack; | |
128 | ||
6de9cd9a DN |
129 | /* Track whether or not we have changed the control flow graph. */ |
130 | static bool cfg_altered; | |
131 | ||
1eaba2f2 | 132 | /* Bitmap of blocks that have had EH statements cleaned. We should |
f6fe65dc | 133 | remove their dead edges eventually. */ |
1eaba2f2 RH |
134 | static bitmap need_eh_cleanup; |
135 | ||
6de9cd9a DN |
136 | /* Statistics for dominator optimizations. */ |
137 | struct opt_stats_d | |
138 | { | |
139 | long num_stmts; | |
140 | long num_exprs_considered; | |
141 | long num_re; | |
142 | }; | |
143 | ||
23530866 JL |
144 | static struct opt_stats_d opt_stats; |
145 | ||
6de9cd9a DN |
146 | /* Value range propagation record. Each time we encounter a conditional |
147 | of the form SSA_NAME COND CONST we create a new vrp_element to record | |
148 | how the condition affects the possible values SSA_NAME may have. | |
149 | ||
150 | Each record contains the condition tested (COND), and the the range of | |
151 | values the variable may legitimately have if COND is true. Note the | |
152 | range of values may be a smaller range than COND specifies if we have | |
153 | recorded other ranges for this variable. Each record also contains the | |
154 | block in which the range was recorded for invalidation purposes. | |
155 | ||
156 | Note that the current known range is computed lazily. This allows us | |
157 | to avoid the overhead of computing ranges which are never queried. | |
158 | ||
159 | When we encounter a conditional, we look for records which constrain | |
160 | the SSA_NAME used in the condition. In some cases those records allow | |
161 | us to determine the condition's result at compile time. In other cases | |
162 | they may allow us to simplify the condition. | |
163 | ||
164 | We also use value ranges to do things like transform signed div/mod | |
165 | operations into unsigned div/mod or to simplify ABS_EXPRs. | |
166 | ||
167 | Simple experiments have shown these optimizations to not be all that | |
168 | useful on switch statements (much to my surprise). So switch statement | |
169 | optimizations are not performed. | |
170 | ||
171 | Note carefully we do not propagate information through each statement | |
454ff5cb | 172 | in the block. i.e., if we know variable X has a value defined of |
6de9cd9a DN |
173 | [0, 25] and we encounter Y = X + 1, we do not track a value range |
174 | for Y (which would be [1, 26] if we cared). Similarly we do not | |
175 | constrain values as we encounter narrowing typecasts, etc. */ | |
176 | ||
177 | struct vrp_element | |
178 | { | |
179 | /* The highest and lowest values the variable in COND may contain when | |
180 | COND is true. Note this may not necessarily be the same values | |
181 | tested by COND if the same variable was used in earlier conditionals. | |
182 | ||
183 | Note this is computed lazily and thus can be NULL indicating that | |
184 | the values have not been computed yet. */ | |
185 | tree low; | |
186 | tree high; | |
187 | ||
188 | /* The actual conditional we recorded. This is needed since we compute | |
189 | ranges lazily. */ | |
190 | tree cond; | |
191 | ||
192 | /* The basic block where this record was created. We use this to determine | |
193 | when to remove records. */ | |
194 | basic_block bb; | |
195 | }; | |
196 | ||
23530866 JL |
197 | /* A hash table holding value range records (VRP_ELEMENTs) for a given |
198 | SSA_NAME. We used to use a varray indexed by SSA_NAME_VERSION, but | |
199 | that gets awful wasteful, particularly since the density objects | |
200 | with useful information is very low. */ | |
201 | static htab_t vrp_data; | |
202 | ||
203 | /* An entry in the VRP_DATA hash table. We record the variable and a | |
204 | varray of VRP_ELEMENT records associated with that variable. */ | |
6de9cd9a | 205 | |
23530866 JL |
206 | struct vrp_hash_elt |
207 | { | |
208 | tree var; | |
209 | varray_type records; | |
210 | }; | |
6de9cd9a | 211 | |
fdabe5c2 JL |
212 | /* Array of variables which have their values constrained by operations |
213 | in this basic block. We use this during finalization to know | |
214 | which variables need their VRP data updated. */ | |
6de9cd9a | 215 | |
fdabe5c2 JL |
216 | /* Stack of SSA_NAMEs which had their values constrainted by operations |
217 | in this basic block. During finalization of this block we use this | |
218 | list to determine which variables need their VRP data updated. | |
219 | ||
220 | A NULL entry marks the end of the SSA_NAMEs associated with this block. */ | |
221 | static varray_type vrp_variables_stack; | |
6de9cd9a DN |
222 | |
223 | struct eq_expr_value | |
224 | { | |
225 | tree src; | |
226 | tree dst; | |
227 | }; | |
228 | ||
229 | /* Local functions. */ | |
230 | static void optimize_stmt (struct dom_walk_data *, | |
231 | basic_block bb, | |
232 | block_stmt_iterator); | |
48732f23 | 233 | static tree lookup_avail_expr (tree, bool); |
fdabe5c2 | 234 | static struct eq_expr_value get_eq_expr_value (tree, int, basic_block); |
23530866 JL |
235 | static hashval_t vrp_hash (const void *); |
236 | static int vrp_eq (const void *, const void *); | |
6de9cd9a | 237 | static hashval_t avail_expr_hash (const void *); |
940db2c8 | 238 | static hashval_t real_avail_expr_hash (const void *); |
6de9cd9a DN |
239 | static int avail_expr_eq (const void *, const void *); |
240 | static void htab_statistics (FILE *, htab_t); | |
48732f23 JL |
241 | static void record_cond (tree, tree); |
242 | static void record_dominating_conditions (tree); | |
b5fefcf6 JL |
243 | static void record_const_or_copy (tree, tree); |
244 | static void record_equality (tree, tree); | |
48732f23 | 245 | static tree update_rhs_and_lookup_avail_expr (tree, tree, bool); |
6de9cd9a | 246 | static tree simplify_rhs_and_lookup_avail_expr (struct dom_walk_data *, |
68b9f53b | 247 | tree, int); |
48732f23 JL |
248 | static tree simplify_cond_and_lookup_avail_expr (tree, stmt_ann_t, int); |
249 | static tree simplify_switch_and_lookup_avail_expr (tree, int); | |
6de9cd9a | 250 | static tree find_equivalent_equality_comparison (tree); |
fdabe5c2 | 251 | static void record_range (tree, basic_block); |
6de9cd9a DN |
252 | static bool extract_range_from_cond (tree, tree *, tree *, int *); |
253 | static void record_equivalences_from_phis (struct dom_walk_data *, basic_block); | |
254 | static void record_equivalences_from_incoming_edge (struct dom_walk_data *, | |
255 | basic_block); | |
256 | static bool eliminate_redundant_computations (struct dom_walk_data *, | |
257 | tree, stmt_ann_t); | |
fdabe5c2 | 258 | static void record_equivalences_from_stmt (tree, int, stmt_ann_t); |
6de9cd9a DN |
259 | static void thread_across_edge (struct dom_walk_data *, edge); |
260 | static void dom_opt_finalize_block (struct dom_walk_data *, basic_block); | |
6de9cd9a DN |
261 | static void dom_opt_initialize_block (struct dom_walk_data *, basic_block); |
262 | static void cprop_into_phis (struct dom_walk_data *, basic_block); | |
48732f23 | 263 | static void remove_local_expressions_from_table (void); |
b5fefcf6 | 264 | static void restore_vars_to_original_value (void); |
9fae925b JL |
265 | static void restore_currdefs_to_original_value (void); |
266 | static void register_definitions_for_stmt (tree); | |
28c008bb | 267 | static edge single_incoming_edge_ignoring_loop_edges (basic_block); |
fdabe5c2 | 268 | static void restore_nonzero_vars_to_original_value (void); |
6de9cd9a DN |
269 | |
270 | /* Local version of fold that doesn't introduce cruft. */ | |
271 | ||
272 | static tree | |
273 | local_fold (tree t) | |
274 | { | |
275 | t = fold (t); | |
276 | ||
277 | /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that | |
278 | may have been added by fold, and "useless" type conversions that might | |
279 | now be apparent due to propagation. */ | |
6de9cd9a DN |
280 | STRIP_USELESS_TYPE_CONVERSION (t); |
281 | ||
282 | return t; | |
283 | } | |
284 | ||
6de9cd9a DN |
285 | /* Jump threading, redundancy elimination and const/copy propagation. |
286 | ||
6de9cd9a DN |
287 | This pass may expose new symbols that need to be renamed into SSA. For |
288 | every new symbol exposed, its corresponding bit will be set in | |
ff2ad0f7 | 289 | VARS_TO_RENAME. */ |
6de9cd9a DN |
290 | |
291 | static void | |
292 | tree_ssa_dominator_optimize (void) | |
293 | { | |
6de9cd9a DN |
294 | struct dom_walk_data walk_data; |
295 | unsigned int i; | |
296 | ||
297 | for (i = 0; i < num_referenced_vars; i++) | |
298 | var_ann (referenced_var (i))->current_def = NULL; | |
299 | ||
300 | /* Mark loop edges so we avoid threading across loop boundaries. | |
301 | This may result in transforming natural loop into irreducible | |
302 | region. */ | |
303 | mark_dfs_back_edges (); | |
304 | ||
305 | /* Create our hash tables. */ | |
940db2c8 | 306 | avail_exprs = htab_create (1024, real_avail_expr_hash, avail_expr_eq, free); |
23530866 | 307 | vrp_data = htab_create (ceil_log2 (num_ssa_names), vrp_hash, vrp_eq, free); |
48732f23 | 308 | VARRAY_TREE_INIT (avail_exprs_stack, 20, "Available expression stack"); |
9fae925b | 309 | VARRAY_TREE_INIT (block_defs_stack, 20, "Block DEFS stack"); |
b5fefcf6 | 310 | VARRAY_TREE_INIT (const_and_copies_stack, 20, "Block const_and_copies stack"); |
fdabe5c2 JL |
311 | VARRAY_TREE_INIT (nonzero_vars_stack, 20, "Block nonzero_vars stack"); |
312 | VARRAY_TREE_INIT (vrp_variables_stack, 20, "Block vrp_variables stack"); | |
23530866 | 313 | VARRAY_TREE_INIT (stmts_to_rescan, 20, "Statements to rescan"); |
6de9cd9a | 314 | nonzero_vars = BITMAP_XMALLOC (); |
1eaba2f2 | 315 | need_eh_cleanup = BITMAP_XMALLOC (); |
6de9cd9a DN |
316 | |
317 | /* Setup callbacks for the generic dominator tree walker. */ | |
318 | walk_data.walk_stmts_backward = false; | |
319 | walk_data.dom_direction = CDI_DOMINATORS; | |
fdabe5c2 | 320 | walk_data.initialize_block_local_data = NULL; |
6de9cd9a DN |
321 | walk_data.before_dom_children_before_stmts = dom_opt_initialize_block; |
322 | walk_data.before_dom_children_walk_stmts = optimize_stmt; | |
323 | walk_data.before_dom_children_after_stmts = cprop_into_phis; | |
324 | walk_data.after_dom_children_before_stmts = NULL; | |
325 | walk_data.after_dom_children_walk_stmts = NULL; | |
326 | walk_data.after_dom_children_after_stmts = dom_opt_finalize_block; | |
327 | /* Right now we only attach a dummy COND_EXPR to the global data pointer. | |
328 | When we attach more stuff we'll need to fill this out with a real | |
329 | structure. */ | |
330 | walk_data.global_data = NULL; | |
fdabe5c2 | 331 | walk_data.block_local_data_size = 0; |
6de9cd9a DN |
332 | |
333 | /* Now initialize the dominator walker. */ | |
334 | init_walk_dominator_tree (&walk_data); | |
335 | ||
6de9cd9a DN |
336 | calculate_dominance_info (CDI_DOMINATORS); |
337 | ||
338 | /* If we prove certain blocks are unreachable, then we want to | |
339 | repeat the dominator optimization process as PHI nodes may | |
340 | have turned into copies which allows better propagation of | |
341 | values. So we repeat until we do not identify any new unreachable | |
342 | blocks. */ | |
343 | do | |
344 | { | |
345 | /* Optimize the dominator tree. */ | |
346 | cfg_altered = false; | |
347 | ||
348 | /* Recursively walk the dominator tree optimizing statements. */ | |
349 | walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); | |
350 | ||
56b043c8 JL |
351 | /* If we exposed any new variables, go ahead and put them into |
352 | SSA form now, before we handle jump threading. This simplifies | |
353 | interactions between rewriting of _DECL nodes into SSA form | |
354 | and rewriting SSA_NAME nodes into SSA form after block | |
355 | duplication and CFG manipulation. */ | |
356 | if (bitmap_first_set_bit (vars_to_rename) >= 0) | |
357 | { | |
358 | rewrite_into_ssa (false); | |
359 | bitmap_clear (vars_to_rename); | |
360 | } | |
6de9cd9a | 361 | |
56b043c8 JL |
362 | /* Thread jumps, creating duplicate blocks as needed. */ |
363 | cfg_altered = thread_through_all_blocks (); | |
6de9cd9a | 364 | |
56b043c8 JL |
365 | /* Removal of statements may make some EH edges dead. Purge |
366 | such edges from the CFG as needed. */ | |
1eaba2f2 RH |
367 | if (bitmap_first_set_bit (need_eh_cleanup) >= 0) |
368 | { | |
56b043c8 | 369 | cfg_altered |= tree_purge_all_dead_eh_edges (need_eh_cleanup); |
1eaba2f2 RH |
370 | bitmap_zero (need_eh_cleanup); |
371 | } | |
372 | ||
56b043c8 JL |
373 | free_dominance_info (CDI_DOMINATORS); |
374 | cfg_altered = cleanup_tree_cfg (); | |
375 | calculate_dominance_info (CDI_DOMINATORS); | |
6de9cd9a | 376 | |
56b043c8 | 377 | rewrite_ssa_into_ssa (); |
6de9cd9a | 378 | |
6de9cd9a DN |
379 | /* Reinitialize the various tables. */ |
380 | bitmap_clear (nonzero_vars); | |
381 | htab_empty (avail_exprs); | |
23530866 | 382 | htab_empty (vrp_data); |
6de9cd9a DN |
383 | |
384 | for (i = 0; i < num_referenced_vars; i++) | |
385 | var_ann (referenced_var (i))->current_def = NULL; | |
386 | } | |
387 | while (cfg_altered); | |
388 | ||
6de9cd9a DN |
389 | /* Debugging dumps. */ |
390 | if (dump_file && (dump_flags & TDF_STATS)) | |
391 | dump_dominator_optimization_stats (dump_file); | |
392 | ||
61ada8ae | 393 | /* We emptied the hash table earlier, now delete it completely. */ |
6de9cd9a | 394 | htab_delete (avail_exprs); |
23530866 | 395 | htab_delete (vrp_data); |
6de9cd9a | 396 | |
1ea7e6ad | 397 | /* It is not necessary to clear CURRDEFS, REDIRECTION_EDGES, VRP_DATA, |
6de9cd9a DN |
398 | CONST_AND_COPIES, and NONZERO_VARS as they all get cleared at the bottom |
399 | of the do-while loop above. */ | |
400 | ||
401 | /* And finalize the dominator walker. */ | |
402 | fini_walk_dominator_tree (&walk_data); | |
cfa4cb00 AP |
403 | |
404 | /* Free nonzero_vars. */ | |
405 | BITMAP_XFREE (nonzero_vars); | |
1eaba2f2 | 406 | BITMAP_XFREE (need_eh_cleanup); |
3aecd08b JL |
407 | |
408 | /* Finally, remove everything except invariants in SSA_NAME_VALUE. | |
409 | ||
410 | Long term we will be able to let everything in SSA_NAME_VALUE | |
411 | persist. However, for now, we know this is the safe thing to | |
412 | do. */ | |
413 | for (i = 0; i < num_ssa_names; i++) | |
414 | { | |
415 | tree name = ssa_name (i); | |
416 | tree value; | |
417 | ||
418 | if (!name) | |
419 | continue; | |
420 | ||
421 | value = SSA_NAME_VALUE (name); | |
422 | if (value && !is_gimple_min_invariant (value)) | |
423 | SSA_NAME_VALUE (name) = NULL; | |
424 | } | |
6de9cd9a DN |
425 | } |
426 | ||
427 | static bool | |
428 | gate_dominator (void) | |
429 | { | |
430 | return flag_tree_dom != 0; | |
431 | } | |
432 | ||
433 | struct tree_opt_pass pass_dominator = | |
434 | { | |
435 | "dom", /* name */ | |
436 | gate_dominator, /* gate */ | |
437 | tree_ssa_dominator_optimize, /* execute */ | |
438 | NULL, /* sub */ | |
439 | NULL, /* next */ | |
440 | 0, /* static_pass_number */ | |
441 | TV_TREE_SSA_DOMINATOR_OPTS, /* tv_id */ | |
c1b763fa | 442 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
6de9cd9a DN |
443 | 0, /* properties_provided */ |
444 | 0, /* properties_destroyed */ | |
445 | 0, /* todo_flags_start */ | |
446 | TODO_dump_func | TODO_rename_vars | |
9f8628ba PB |
447 | | TODO_verify_ssa, /* todo_flags_finish */ |
448 | 0 /* letter */ | |
6de9cd9a DN |
449 | }; |
450 | ||
451 | ||
452 | /* We are exiting BB, see if the target block begins with a conditional | |
453 | jump which has a known value when reached via BB. */ | |
454 | ||
455 | static void | |
456 | thread_across_edge (struct dom_walk_data *walk_data, edge e) | |
457 | { | |
6de9cd9a DN |
458 | block_stmt_iterator bsi; |
459 | tree stmt = NULL; | |
460 | tree phi; | |
461 | ||
462 | /* Each PHI creates a temporary equivalence, record them. */ | |
17192884 | 463 | for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a | 464 | { |
d00ad49b | 465 | tree src = PHI_ARG_DEF_FROM_EDGE (phi, e); |
6de9cd9a | 466 | tree dst = PHI_RESULT (phi); |
b5fefcf6 | 467 | record_const_or_copy (dst, src); |
9fae925b | 468 | register_new_def (dst, &block_defs_stack); |
6de9cd9a DN |
469 | } |
470 | ||
471 | for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi)) | |
472 | { | |
473 | tree lhs, cached_lhs; | |
474 | ||
475 | stmt = bsi_stmt (bsi); | |
476 | ||
477 | /* Ignore empty statements and labels. */ | |
478 | if (IS_EMPTY_STMT (stmt) || TREE_CODE (stmt) == LABEL_EXPR) | |
479 | continue; | |
480 | ||
481 | /* If this is not a MODIFY_EXPR which sets an SSA_NAME to a new | |
482 | value, then stop our search here. Ideally when we stop a | |
483 | search we stop on a COND_EXPR or SWITCH_EXPR. */ | |
484 | if (TREE_CODE (stmt) != MODIFY_EXPR | |
485 | || TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME) | |
486 | break; | |
487 | ||
488 | /* At this point we have a statement which assigns an RHS to an | |
489 | SSA_VAR on the LHS. We want to prove that the RHS is already | |
490 | available and that its value is held in the current definition | |
491 | of the LHS -- meaning that this assignment is a NOP when | |
492 | reached via edge E. */ | |
493 | if (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME) | |
494 | cached_lhs = TREE_OPERAND (stmt, 1); | |
495 | else | |
48732f23 | 496 | cached_lhs = lookup_avail_expr (stmt, false); |
6de9cd9a DN |
497 | |
498 | lhs = TREE_OPERAND (stmt, 0); | |
499 | ||
500 | /* This can happen if we thread around to the start of a loop. */ | |
501 | if (lhs == cached_lhs) | |
502 | break; | |
503 | ||
504 | /* If we did not find RHS in the hash table, then try again after | |
505 | temporarily const/copy propagating the operands. */ | |
506 | if (!cached_lhs) | |
507 | { | |
508 | /* Copy the operands. */ | |
509 | stmt_ann_t ann = stmt_ann (stmt); | |
510 | use_optype uses = USE_OPS (ann); | |
511 | vuse_optype vuses = VUSE_OPS (ann); | |
512 | tree *uses_copy = xcalloc (NUM_USES (uses), sizeof (tree)); | |
513 | tree *vuses_copy = xcalloc (NUM_VUSES (vuses), sizeof (tree)); | |
514 | unsigned int i; | |
515 | ||
516 | /* Make a copy of the uses into USES_COPY, then cprop into | |
517 | the use operands. */ | |
518 | for (i = 0; i < NUM_USES (uses); i++) | |
519 | { | |
520 | tree tmp = NULL; | |
521 | ||
522 | uses_copy[i] = USE_OP (uses, i); | |
523 | if (TREE_CODE (USE_OP (uses, i)) == SSA_NAME) | |
3aecd08b JL |
524 | tmp = SSA_NAME_VALUE (USE_OP (uses, i)); |
525 | if (tmp && TREE_CODE (tmp) != VALUE_HANDLE) | |
d00ad49b | 526 | SET_USE_OP (uses, i, tmp); |
6de9cd9a DN |
527 | } |
528 | ||
529 | /* Similarly for virtual uses. */ | |
530 | for (i = 0; i < NUM_VUSES (vuses); i++) | |
531 | { | |
532 | tree tmp = NULL; | |
533 | ||
534 | vuses_copy[i] = VUSE_OP (vuses, i); | |
535 | if (TREE_CODE (VUSE_OP (vuses, i)) == SSA_NAME) | |
3aecd08b JL |
536 | tmp = SSA_NAME_VALUE (VUSE_OP (vuses, i)); |
537 | if (tmp && TREE_CODE (tmp) != VALUE_HANDLE) | |
d00ad49b | 538 | SET_VUSE_OP (vuses, i, tmp); |
6de9cd9a DN |
539 | } |
540 | ||
541 | /* Try to lookup the new expression. */ | |
48732f23 | 542 | cached_lhs = lookup_avail_expr (stmt, false); |
6de9cd9a DN |
543 | |
544 | /* Restore the statement's original uses/defs. */ | |
545 | for (i = 0; i < NUM_USES (uses); i++) | |
d00ad49b | 546 | SET_USE_OP (uses, i, uses_copy[i]); |
6de9cd9a DN |
547 | |
548 | for (i = 0; i < NUM_VUSES (vuses); i++) | |
d00ad49b | 549 | SET_VUSE_OP (vuses, i, vuses_copy[i]); |
6de9cd9a DN |
550 | |
551 | free (uses_copy); | |
552 | free (vuses_copy); | |
553 | ||
554 | /* If we still did not find the expression in the hash table, | |
555 | then we can not ignore this statement. */ | |
556 | if (! cached_lhs) | |
557 | break; | |
558 | } | |
559 | ||
560 | /* If the expression in the hash table was not assigned to an | |
561 | SSA_NAME, then we can not ignore this statement. */ | |
562 | if (TREE_CODE (cached_lhs) != SSA_NAME) | |
563 | break; | |
564 | ||
565 | /* If we have different underlying variables, then we can not | |
566 | ignore this statement. */ | |
567 | if (SSA_NAME_VAR (cached_lhs) != SSA_NAME_VAR (lhs)) | |
568 | break; | |
569 | ||
570 | /* If CACHED_LHS does not represent the current value of the undering | |
571 | variable in CACHED_LHS/LHS, then we can not ignore this statement. */ | |
572 | if (var_ann (SSA_NAME_VAR (lhs))->current_def != cached_lhs) | |
573 | break; | |
574 | ||
575 | /* If we got here, then we can ignore this statement and continue | |
576 | walking through the statements in the block looking for a threadable | |
577 | COND_EXPR. | |
578 | ||
579 | We want to record an equivalence lhs = cache_lhs so that if | |
580 | the result of this statement is used later we can copy propagate | |
581 | suitably. */ | |
b5fefcf6 | 582 | record_const_or_copy (lhs, cached_lhs); |
9fae925b | 583 | register_new_def (lhs, &block_defs_stack); |
6de9cd9a DN |
584 | } |
585 | ||
586 | /* If we stopped at a COND_EXPR or SWITCH_EXPR, then see if we know which | |
587 | arm will be taken. */ | |
588 | if (stmt | |
589 | && (TREE_CODE (stmt) == COND_EXPR | |
590 | || TREE_CODE (stmt) == SWITCH_EXPR)) | |
591 | { | |
592 | tree cond, cached_lhs; | |
593 | edge e1; | |
628f6a4e | 594 | edge_iterator ei; |
6de9cd9a DN |
595 | |
596 | /* Do not forward entry edges into the loop. In the case loop | |
597 | has multiple entry edges we may end up in constructing irreducible | |
598 | region. | |
599 | ??? We may consider forwarding the edges in the case all incoming | |
600 | edges forward to the same destination block. */ | |
601 | if (!e->flags & EDGE_DFS_BACK) | |
602 | { | |
628f6a4e | 603 | FOR_EACH_EDGE (e1, ei, e->dest->preds) |
6de9cd9a DN |
604 | if (e1->flags & EDGE_DFS_BACK) |
605 | break; | |
606 | if (e1) | |
607 | return; | |
608 | } | |
609 | ||
610 | /* Now temporarily cprop the operands and try to find the resulting | |
611 | expression in the hash tables. */ | |
612 | if (TREE_CODE (stmt) == COND_EXPR) | |
613 | cond = COND_EXPR_COND (stmt); | |
614 | else | |
615 | cond = SWITCH_COND (stmt); | |
616 | ||
6615c446 | 617 | if (COMPARISON_CLASS_P (cond)) |
6de9cd9a DN |
618 | { |
619 | tree dummy_cond, op0, op1; | |
620 | enum tree_code cond_code; | |
621 | ||
622 | op0 = TREE_OPERAND (cond, 0); | |
623 | op1 = TREE_OPERAND (cond, 1); | |
624 | cond_code = TREE_CODE (cond); | |
625 | ||
626 | /* Get the current value of both operands. */ | |
627 | if (TREE_CODE (op0) == SSA_NAME) | |
628 | { | |
3aecd08b JL |
629 | tree tmp = SSA_NAME_VALUE (op0); |
630 | if (tmp && TREE_CODE (tmp) != VALUE_HANDLE) | |
6de9cd9a DN |
631 | op0 = tmp; |
632 | } | |
633 | ||
634 | if (TREE_CODE (op1) == SSA_NAME) | |
635 | { | |
3aecd08b JL |
636 | tree tmp = SSA_NAME_VALUE (op1); |
637 | if (tmp && TREE_CODE (tmp) != VALUE_HANDLE) | |
6de9cd9a DN |
638 | op1 = tmp; |
639 | } | |
640 | ||
641 | /* Stuff the operator and operands into our dummy conditional | |
642 | expression, creating the dummy conditional if necessary. */ | |
643 | dummy_cond = walk_data->global_data; | |
644 | if (! dummy_cond) | |
645 | { | |
646 | dummy_cond = build (cond_code, boolean_type_node, op0, op1); | |
647 | dummy_cond = build (COND_EXPR, void_type_node, | |
648 | dummy_cond, NULL, NULL); | |
649 | walk_data->global_data = dummy_cond; | |
650 | } | |
651 | else | |
652 | { | |
653 | TREE_SET_CODE (TREE_OPERAND (dummy_cond, 0), cond_code); | |
654 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 0) = op0; | |
655 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 1) = op1; | |
656 | } | |
657 | ||
658 | /* If the conditional folds to an invariant, then we are done, | |
659 | otherwise look it up in the hash tables. */ | |
660 | cached_lhs = local_fold (COND_EXPR_COND (dummy_cond)); | |
661 | if (! is_gimple_min_invariant (cached_lhs)) | |
48732f23 | 662 | cached_lhs = lookup_avail_expr (dummy_cond, false); |
6de9cd9a DN |
663 | if (!cached_lhs || ! is_gimple_min_invariant (cached_lhs)) |
664 | { | |
6de9cd9a | 665 | cached_lhs = simplify_cond_and_lookup_avail_expr (dummy_cond, |
68b9f53b | 666 | NULL, |
6de9cd9a DN |
667 | false); |
668 | } | |
669 | } | |
670 | /* We can have conditionals which just test the state of a | |
671 | variable rather than use a relational operator. These are | |
672 | simpler to handle. */ | |
673 | else if (TREE_CODE (cond) == SSA_NAME) | |
674 | { | |
675 | cached_lhs = cond; | |
3aecd08b | 676 | cached_lhs = SSA_NAME_VALUE (cached_lhs); |
6de9cd9a DN |
677 | if (cached_lhs && ! is_gimple_min_invariant (cached_lhs)) |
678 | cached_lhs = 0; | |
679 | } | |
680 | else | |
48732f23 | 681 | cached_lhs = lookup_avail_expr (stmt, false); |
6de9cd9a DN |
682 | |
683 | if (cached_lhs) | |
684 | { | |
685 | edge taken_edge = find_taken_edge (e->dest, cached_lhs); | |
686 | basic_block dest = (taken_edge ? taken_edge->dest : NULL); | |
687 | ||
8a78744f | 688 | if (dest == e->dest) |
6de9cd9a DN |
689 | return; |
690 | ||
691 | /* If we have a known destination for the conditional, then | |
692 | we can perform this optimization, which saves at least one | |
693 | conditional jump each time it applies since we get to | |
56b043c8 | 694 | bypass the conditional at our original destination. */ |
6de9cd9a DN |
695 | if (dest) |
696 | { | |
15db5571 JH |
697 | update_bb_profile_for_threading (e->dest, EDGE_FREQUENCY (e), |
698 | e->count, taken_edge); | |
56b043c8 JL |
699 | e->aux = taken_edge; |
700 | bb_ann (e->dest)->incoming_edge_threaded = true; | |
6de9cd9a DN |
701 | } |
702 | } | |
703 | } | |
704 | } | |
705 | ||
706 | ||
6de9cd9a DN |
707 | /* Initialize local stacks for this optimizer and record equivalences |
708 | upon entry to BB. Equivalences can come from the edge traversed to | |
709 | reach BB or they may come from PHI nodes at the start of BB. */ | |
710 | ||
711 | static void | |
712 | dom_opt_initialize_block (struct dom_walk_data *walk_data, basic_block bb) | |
713 | { | |
714 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
715 | fprintf (dump_file, "\n\nOptimizing block #%d\n\n", bb->index); | |
716 | ||
9fae925b JL |
717 | /* Push a marker on the stacks of local information so that we know how |
718 | far to unwind when we finalize this block. */ | |
48732f23 | 719 | VARRAY_PUSH_TREE (avail_exprs_stack, NULL_TREE); |
9fae925b | 720 | VARRAY_PUSH_TREE (block_defs_stack, NULL_TREE); |
b5fefcf6 | 721 | VARRAY_PUSH_TREE (const_and_copies_stack, NULL_TREE); |
fdabe5c2 JL |
722 | VARRAY_PUSH_TREE (nonzero_vars_stack, NULL_TREE); |
723 | VARRAY_PUSH_TREE (vrp_variables_stack, NULL_TREE); | |
48732f23 | 724 | |
6de9cd9a DN |
725 | record_equivalences_from_incoming_edge (walk_data, bb); |
726 | ||
727 | /* PHI nodes can create equivalences too. */ | |
728 | record_equivalences_from_phis (walk_data, bb); | |
729 | } | |
730 | ||
731 | /* Given an expression EXPR (a relational expression or a statement), | |
732 | initialize the hash table element pointed by by ELEMENT. */ | |
733 | ||
734 | static void | |
735 | initialize_hash_element (tree expr, tree lhs, struct expr_hash_elt *element) | |
736 | { | |
737 | /* Hash table elements may be based on conditional expressions or statements. | |
738 | ||
739 | For the former case, we have no annotation and we want to hash the | |
740 | conditional expression. In the latter case we have an annotation and | |
741 | we want to record the expression the statement evaluates. */ | |
6615c446 | 742 | if (COMPARISON_CLASS_P (expr) || TREE_CODE (expr) == TRUTH_NOT_EXPR) |
6de9cd9a DN |
743 | { |
744 | element->ann = NULL; | |
745 | element->rhs = expr; | |
746 | } | |
747 | else if (TREE_CODE (expr) == COND_EXPR) | |
748 | { | |
749 | element->ann = stmt_ann (expr); | |
750 | element->rhs = COND_EXPR_COND (expr); | |
751 | } | |
752 | else if (TREE_CODE (expr) == SWITCH_EXPR) | |
753 | { | |
754 | element->ann = stmt_ann (expr); | |
755 | element->rhs = SWITCH_COND (expr); | |
756 | } | |
757 | else if (TREE_CODE (expr) == RETURN_EXPR && TREE_OPERAND (expr, 0)) | |
758 | { | |
759 | element->ann = stmt_ann (expr); | |
760 | element->rhs = TREE_OPERAND (TREE_OPERAND (expr, 0), 1); | |
761 | } | |
762 | else | |
763 | { | |
764 | element->ann = stmt_ann (expr); | |
765 | element->rhs = TREE_OPERAND (expr, 1); | |
766 | } | |
767 | ||
768 | element->lhs = lhs; | |
769 | element->hash = avail_expr_hash (element); | |
770 | } | |
771 | ||
772 | /* Remove all the expressions in LOCALS from TABLE, stopping when there are | |
773 | LIMIT entries left in LOCALs. */ | |
774 | ||
775 | static void | |
48732f23 | 776 | remove_local_expressions_from_table (void) |
6de9cd9a | 777 | { |
6de9cd9a | 778 | /* Remove all the expressions made available in this block. */ |
48732f23 | 779 | while (VARRAY_ACTIVE_SIZE (avail_exprs_stack) > 0) |
6de9cd9a DN |
780 | { |
781 | struct expr_hash_elt element; | |
48732f23 JL |
782 | tree expr = VARRAY_TOP_TREE (avail_exprs_stack); |
783 | VARRAY_POP (avail_exprs_stack); | |
784 | ||
785 | if (expr == NULL_TREE) | |
786 | break; | |
6de9cd9a DN |
787 | |
788 | initialize_hash_element (expr, NULL, &element); | |
48732f23 | 789 | htab_remove_elt_with_hash (avail_exprs, &element, element.hash); |
6de9cd9a DN |
790 | } |
791 | } | |
792 | ||
793 | /* Use the SSA_NAMES in LOCALS to restore TABLE to its original | |
1ea7e6ad | 794 | state, stopping when there are LIMIT entries left in LOCALs. */ |
6de9cd9a DN |
795 | |
796 | static void | |
76fd4fd7 | 797 | restore_nonzero_vars_to_original_value (void) |
6de9cd9a | 798 | { |
fdabe5c2 | 799 | while (VARRAY_ACTIVE_SIZE (nonzero_vars_stack) > 0) |
6de9cd9a | 800 | { |
fdabe5c2 JL |
801 | tree name = VARRAY_TOP_TREE (nonzero_vars_stack); |
802 | VARRAY_POP (nonzero_vars_stack); | |
803 | ||
804 | if (name == NULL) | |
805 | break; | |
806 | ||
807 | bitmap_clear_bit (nonzero_vars, SSA_NAME_VERSION (name)); | |
6de9cd9a DN |
808 | } |
809 | } | |
810 | ||
b5fefcf6 JL |
811 | /* Use the source/dest pairs in CONST_AND_COPIES_STACK to restore |
812 | CONST_AND_COPIES to its original state, stopping when we hit a | |
813 | NULL marker. */ | |
6de9cd9a DN |
814 | |
815 | static void | |
b5fefcf6 | 816 | restore_vars_to_original_value (void) |
6de9cd9a | 817 | { |
b5fefcf6 | 818 | while (VARRAY_ACTIVE_SIZE (const_and_copies_stack) > 0) |
6de9cd9a DN |
819 | { |
820 | tree prev_value, dest; | |
821 | ||
b5fefcf6 JL |
822 | dest = VARRAY_TOP_TREE (const_and_copies_stack); |
823 | VARRAY_POP (const_and_copies_stack); | |
6de9cd9a | 824 | |
b5fefcf6 JL |
825 | if (dest == NULL) |
826 | break; | |
827 | ||
828 | prev_value = VARRAY_TOP_TREE (const_and_copies_stack); | |
829 | VARRAY_POP (const_and_copies_stack); | |
830 | ||
3aecd08b | 831 | SSA_NAME_VALUE (dest) = prev_value; |
6de9cd9a DN |
832 | } |
833 | } | |
834 | ||
835 | /* Similar to restore_vars_to_original_value, except that it restores | |
836 | CURRDEFS to its original value. */ | |
837 | static void | |
9fae925b | 838 | restore_currdefs_to_original_value (void) |
6de9cd9a | 839 | { |
6de9cd9a | 840 | /* Restore CURRDEFS to its original state. */ |
9fae925b | 841 | while (VARRAY_ACTIVE_SIZE (block_defs_stack) > 0) |
6de9cd9a | 842 | { |
9fae925b | 843 | tree tmp = VARRAY_TOP_TREE (block_defs_stack); |
6de9cd9a DN |
844 | tree saved_def, var; |
845 | ||
9fae925b JL |
846 | VARRAY_POP (block_defs_stack); |
847 | ||
848 | if (tmp == NULL_TREE) | |
849 | break; | |
6de9cd9a DN |
850 | |
851 | /* If we recorded an SSA_NAME, then make the SSA_NAME the current | |
852 | definition of its underlying variable. If we recorded anything | |
853 | else, it must have been an _DECL node and its current reaching | |
854 | definition must have been NULL. */ | |
855 | if (TREE_CODE (tmp) == SSA_NAME) | |
856 | { | |
857 | saved_def = tmp; | |
858 | var = SSA_NAME_VAR (saved_def); | |
859 | } | |
860 | else | |
861 | { | |
862 | saved_def = NULL; | |
863 | var = tmp; | |
864 | } | |
865 | ||
866 | var_ann (var)->current_def = saved_def; | |
867 | } | |
868 | } | |
869 | ||
870 | /* We have finished processing the dominator children of BB, perform | |
871 | any finalization actions in preparation for leaving this node in | |
872 | the dominator tree. */ | |
873 | ||
874 | static void | |
875 | dom_opt_finalize_block (struct dom_walk_data *walk_data, basic_block bb) | |
876 | { | |
6de9cd9a DN |
877 | tree last; |
878 | ||
879 | /* If we are at a leaf node in the dominator graph, see if we can thread | |
880 | the edge from BB through its successor. | |
881 | ||
882 | Do this before we remove entries from our equivalence tables. */ | |
628f6a4e BE |
883 | if (EDGE_COUNT (bb->succs) == 1 |
884 | && (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) == 0 | |
885 | && (get_immediate_dominator (CDI_DOMINATORS, EDGE_SUCC (bb, 0)->dest) != bb | |
886 | || phi_nodes (EDGE_SUCC (bb, 0)->dest))) | |
6de9cd9a DN |
887 | |
888 | { | |
628f6a4e | 889 | thread_across_edge (walk_data, EDGE_SUCC (bb, 0)); |
6de9cd9a DN |
890 | } |
891 | else if ((last = last_stmt (bb)) | |
892 | && TREE_CODE (last) == COND_EXPR | |
6615c446 | 893 | && (COMPARISON_CLASS_P (COND_EXPR_COND (last)) |
6de9cd9a | 894 | || TREE_CODE (COND_EXPR_COND (last)) == SSA_NAME) |
628f6a4e BE |
895 | && EDGE_COUNT (bb->succs) == 2 |
896 | && (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) == 0 | |
897 | && (EDGE_SUCC (bb, 1)->flags & EDGE_ABNORMAL) == 0) | |
6de9cd9a DN |
898 | { |
899 | edge true_edge, false_edge; | |
900 | tree cond, inverted = NULL; | |
901 | enum tree_code cond_code; | |
902 | ||
903 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
904 | ||
905 | cond = COND_EXPR_COND (last); | |
906 | cond_code = TREE_CODE (cond); | |
907 | ||
6615c446 | 908 | if (TREE_CODE_CLASS (cond_code) == tcc_comparison) |
6de9cd9a DN |
909 | inverted = invert_truthvalue (cond); |
910 | ||
911 | /* If the THEN arm is the end of a dominator tree or has PHI nodes, | |
912 | then try to thread through its edge. */ | |
913 | if (get_immediate_dominator (CDI_DOMINATORS, true_edge->dest) != bb | |
914 | || phi_nodes (true_edge->dest)) | |
915 | { | |
48732f23 JL |
916 | /* Push a marker onto the available expression stack so that we |
917 | unwind any expressions related to the TRUE arm before processing | |
918 | the false arm below. */ | |
919 | VARRAY_PUSH_TREE (avail_exprs_stack, NULL_TREE); | |
9fae925b | 920 | VARRAY_PUSH_TREE (block_defs_stack, NULL_TREE); |
b5fefcf6 | 921 | VARRAY_PUSH_TREE (const_and_copies_stack, NULL_TREE); |
48732f23 | 922 | |
6de9cd9a | 923 | /* Record any equivalences created by following this edge. */ |
6615c446 | 924 | if (TREE_CODE_CLASS (cond_code) == tcc_comparison) |
6de9cd9a | 925 | { |
48732f23 JL |
926 | record_cond (cond, boolean_true_node); |
927 | record_dominating_conditions (cond); | |
928 | record_cond (inverted, boolean_false_node); | |
6de9cd9a DN |
929 | } |
930 | else if (cond_code == SSA_NAME) | |
b5fefcf6 | 931 | record_const_or_copy (cond, boolean_true_node); |
6de9cd9a DN |
932 | |
933 | /* Now thread the edge. */ | |
934 | thread_across_edge (walk_data, true_edge); | |
935 | ||
936 | /* And restore the various tables to their state before | |
937 | we threaded this edge. */ | |
48732f23 | 938 | remove_local_expressions_from_table (); |
b5fefcf6 | 939 | restore_vars_to_original_value (); |
9fae925b | 940 | restore_currdefs_to_original_value (); |
6de9cd9a DN |
941 | } |
942 | ||
943 | /* Similarly for the ELSE arm. */ | |
944 | if (get_immediate_dominator (CDI_DOMINATORS, false_edge->dest) != bb | |
945 | || phi_nodes (false_edge->dest)) | |
946 | { | |
947 | /* Record any equivalences created by following this edge. */ | |
6615c446 | 948 | if (TREE_CODE_CLASS (cond_code) == tcc_comparison) |
6de9cd9a | 949 | { |
48732f23 JL |
950 | record_cond (cond, boolean_false_node); |
951 | record_cond (inverted, boolean_true_node); | |
952 | record_dominating_conditions (inverted); | |
6de9cd9a DN |
953 | } |
954 | else if (cond_code == SSA_NAME) | |
b5fefcf6 | 955 | record_const_or_copy (cond, boolean_false_node); |
6de9cd9a DN |
956 | |
957 | thread_across_edge (walk_data, false_edge); | |
958 | ||
959 | /* No need to remove local expressions from our tables | |
960 | or restore vars to their original value as that will | |
961 | be done immediately below. */ | |
962 | } | |
963 | } | |
964 | ||
48732f23 | 965 | remove_local_expressions_from_table (); |
fdabe5c2 | 966 | restore_nonzero_vars_to_original_value (); |
b5fefcf6 | 967 | restore_vars_to_original_value (); |
9fae925b | 968 | restore_currdefs_to_original_value (); |
6de9cd9a DN |
969 | |
970 | /* Remove VRP records associated with this basic block. They are no | |
971 | longer valid. | |
972 | ||
973 | To be efficient, we note which variables have had their values | |
974 | constrained in this block. So walk over each variable in the | |
975 | VRP_VARIABLEs array. */ | |
fdabe5c2 | 976 | while (VARRAY_ACTIVE_SIZE (vrp_variables_stack) > 0) |
6de9cd9a | 977 | { |
fdabe5c2 | 978 | tree var = VARRAY_TOP_TREE (vrp_variables_stack); |
b8545fbf | 979 | struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p; |
23530866 | 980 | void **slot; |
6de9cd9a DN |
981 | |
982 | /* Each variable has a stack of value range records. We want to | |
983 | invalidate those associated with our basic block. So we walk | |
984 | the array backwards popping off records associated with our | |
985 | block. Once we hit a record not associated with our block | |
986 | we are done. */ | |
fdabe5c2 JL |
987 | varray_type var_vrp_records; |
988 | ||
989 | VARRAY_POP (vrp_variables_stack); | |
990 | ||
991 | if (var == NULL) | |
992 | break; | |
6de9cd9a | 993 | |
23530866 JL |
994 | vrp_hash_elt.var = var; |
995 | vrp_hash_elt.records = NULL; | |
996 | ||
997 | slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT); | |
998 | ||
b8545fbf JL |
999 | vrp_hash_elt_p = (struct vrp_hash_elt *) *slot; |
1000 | var_vrp_records = vrp_hash_elt_p->records; | |
1001 | ||
6de9cd9a DN |
1002 | while (VARRAY_ACTIVE_SIZE (var_vrp_records) > 0) |
1003 | { | |
1004 | struct vrp_element *element | |
1005 | = (struct vrp_element *)VARRAY_TOP_GENERIC_PTR (var_vrp_records); | |
1006 | ||
1007 | if (element->bb != bb) | |
1008 | break; | |
1009 | ||
1010 | VARRAY_POP (var_vrp_records); | |
1011 | } | |
6de9cd9a DN |
1012 | } |
1013 | ||
a6e1aa26 JL |
1014 | /* If we queued any statements to rescan in this block, then |
1015 | go ahead and rescan them now. */ | |
1016 | while (VARRAY_ACTIVE_SIZE (stmts_to_rescan) > 0) | |
6de9cd9a | 1017 | { |
a6e1aa26 JL |
1018 | tree stmt = VARRAY_TOP_TREE (stmts_to_rescan); |
1019 | basic_block stmt_bb = bb_for_stmt (stmt); | |
1020 | ||
1021 | if (stmt_bb != bb) | |
1022 | break; | |
1023 | ||
1024 | VARRAY_POP (stmts_to_rescan); | |
6de9cd9a DN |
1025 | mark_new_vars_to_rename (stmt, vars_to_rename); |
1026 | } | |
1027 | } | |
1028 | ||
1029 | /* PHI nodes can create equivalences too. | |
1030 | ||
1031 | Ignoring any alternatives which are the same as the result, if | |
1032 | all the alternatives are equal, then the PHI node creates an | |
dd747311 JL |
1033 | equivalence. |
1034 | ||
1035 | Additionally, if all the PHI alternatives are known to have a nonzero | |
1036 | value, then the result of this PHI is known to have a nonzero value, | |
1037 | even if we do not know its exact value. */ | |
1038 | ||
6de9cd9a | 1039 | static void |
9fae925b JL |
1040 | record_equivalences_from_phis (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, |
1041 | basic_block bb) | |
6de9cd9a | 1042 | { |
6de9cd9a DN |
1043 | tree phi; |
1044 | ||
17192884 | 1045 | for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
1046 | { |
1047 | tree lhs = PHI_RESULT (phi); | |
1048 | tree rhs = NULL; | |
1049 | int i; | |
1050 | ||
1051 | for (i = 0; i < PHI_NUM_ARGS (phi); i++) | |
1052 | { | |
1053 | tree t = PHI_ARG_DEF (phi, i); | |
1054 | ||
1055 | if (TREE_CODE (t) == SSA_NAME || is_gimple_min_invariant (t)) | |
1056 | { | |
1057 | /* Ignore alternatives which are the same as our LHS. */ | |
1058 | if (operand_equal_p (lhs, t, 0)) | |
1059 | continue; | |
1060 | ||
1061 | /* If we have not processed an alternative yet, then set | |
1062 | RHS to this alternative. */ | |
1063 | if (rhs == NULL) | |
1064 | rhs = t; | |
1065 | /* If we have processed an alternative (stored in RHS), then | |
1066 | see if it is equal to this one. If it isn't, then stop | |
1067 | the search. */ | |
1068 | else if (! operand_equal_p (rhs, t, 0)) | |
1069 | break; | |
1070 | } | |
1071 | else | |
1072 | break; | |
1073 | } | |
1074 | ||
1075 | /* If we had no interesting alternatives, then all the RHS alternatives | |
1076 | must have been the same as LHS. */ | |
1077 | if (!rhs) | |
1078 | rhs = lhs; | |
1079 | ||
1080 | /* If we managed to iterate through each PHI alternative without | |
1081 | breaking out of the loop, then we have a PHI which may create | |
1082 | a useful equivalence. We do not need to record unwind data for | |
1083 | this, since this is a true assignment and not an equivalence | |
1ea7e6ad | 1084 | inferred from a comparison. All uses of this ssa name are dominated |
6de9cd9a DN |
1085 | by this assignment, so unwinding just costs time and space. */ |
1086 | if (i == PHI_NUM_ARGS (phi) | |
1087 | && may_propagate_copy (lhs, rhs)) | |
3aecd08b | 1088 | SSA_NAME_VALUE (lhs) = rhs; |
6de9cd9a | 1089 | |
dd747311 JL |
1090 | /* Now see if we know anything about the nonzero property for the |
1091 | result of this PHI. */ | |
1092 | for (i = 0; i < PHI_NUM_ARGS (phi); i++) | |
1093 | { | |
1094 | if (!PHI_ARG_NONZERO (phi, i)) | |
1095 | break; | |
1096 | } | |
1097 | ||
1098 | if (i == PHI_NUM_ARGS (phi)) | |
1099 | bitmap_set_bit (nonzero_vars, SSA_NAME_VERSION (PHI_RESULT (phi))); | |
1100 | ||
9fae925b | 1101 | register_new_def (lhs, &block_defs_stack); |
6de9cd9a DN |
1102 | } |
1103 | } | |
1104 | ||
28c008bb JL |
1105 | /* Ignoring loop backedges, if BB has precisely one incoming edge then |
1106 | return that edge. Otherwise return NULL. */ | |
1107 | static edge | |
1108 | single_incoming_edge_ignoring_loop_edges (basic_block bb) | |
1109 | { | |
1110 | edge retval = NULL; | |
1111 | edge e; | |
628f6a4e | 1112 | edge_iterator ei; |
28c008bb | 1113 | |
628f6a4e | 1114 | FOR_EACH_EDGE (e, ei, bb->preds) |
28c008bb JL |
1115 | { |
1116 | /* A loop back edge can be identified by the destination of | |
1117 | the edge dominating the source of the edge. */ | |
1118 | if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) | |
1119 | continue; | |
1120 | ||
1121 | /* If we have already seen a non-loop edge, then we must have | |
1122 | multiple incoming non-loop edges and thus we return NULL. */ | |
1123 | if (retval) | |
1124 | return NULL; | |
1125 | ||
1126 | /* This is the first non-loop incoming edge we have found. Record | |
1127 | it. */ | |
1128 | retval = e; | |
1129 | } | |
1130 | ||
1131 | return retval; | |
1132 | } | |
1133 | ||
6de9cd9a DN |
1134 | /* Record any equivalences created by the incoming edge to BB. If BB |
1135 | has more than one incoming edge, then no equivalence is created. */ | |
1136 | ||
1137 | static void | |
fdabe5c2 | 1138 | record_equivalences_from_incoming_edge (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, |
6de9cd9a DN |
1139 | basic_block bb) |
1140 | { | |
1141 | int edge_flags; | |
1142 | basic_block parent; | |
1143 | struct eq_expr_value eq_expr_value; | |
1144 | tree parent_block_last_stmt = NULL; | |
6de9cd9a DN |
1145 | |
1146 | /* If our parent block ended with a control statment, then we may be | |
1147 | able to record some equivalences based on which outgoing edge from | |
1148 | the parent was followed. */ | |
1149 | parent = get_immediate_dominator (CDI_DOMINATORS, bb); | |
1150 | if (parent) | |
1151 | { | |
1152 | parent_block_last_stmt = last_stmt (parent); | |
1153 | if (parent_block_last_stmt && !is_ctrl_stmt (parent_block_last_stmt)) | |
1154 | parent_block_last_stmt = NULL; | |
1155 | } | |
1156 | ||
1157 | eq_expr_value.src = NULL; | |
1158 | eq_expr_value.dst = NULL; | |
1159 | ||
28c008bb JL |
1160 | /* If we have a single predecessor (ignoring loop backedges), then extract |
1161 | EDGE_FLAGS from the single incoming edge. Otherwise just return as | |
1162 | there is nothing to do. */ | |
628f6a4e | 1163 | if (EDGE_COUNT (bb->preds) >= 1 |
28c008bb | 1164 | && parent_block_last_stmt) |
6de9cd9a | 1165 | { |
28c008bb JL |
1166 | edge e = single_incoming_edge_ignoring_loop_edges (bb); |
1167 | if (e && bb_for_stmt (parent_block_last_stmt) == e->src) | |
1168 | edge_flags = e->flags; | |
1169 | else | |
1170 | return; | |
6de9cd9a DN |
1171 | } |
1172 | else | |
28c008bb | 1173 | return; |
6de9cd9a DN |
1174 | |
1175 | /* If our parent block ended in a COND_EXPR, add any equivalences | |
1176 | created by the COND_EXPR to the hash table and initialize | |
1177 | EQ_EXPR_VALUE appropriately. | |
1178 | ||
1179 | EQ_EXPR_VALUE is an assignment expression created when BB's immediate | |
1180 | dominator ends in a COND_EXPR statement whose predicate is of the form | |
1181 | 'VAR == VALUE', where VALUE may be another variable or a constant. | |
1182 | This is used to propagate VALUE on the THEN_CLAUSE of that | |
1183 | conditional. This assignment is inserted in CONST_AND_COPIES so that | |
1184 | the copy and constant propagator can find more propagation | |
1185 | opportunities. */ | |
28c008bb | 1186 | if (TREE_CODE (parent_block_last_stmt) == COND_EXPR |
6de9cd9a DN |
1187 | && (edge_flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) |
1188 | eq_expr_value = get_eq_expr_value (parent_block_last_stmt, | |
1189 | (edge_flags & EDGE_TRUE_VALUE) != 0, | |
fdabe5c2 | 1190 | bb); |
1c052514 SB |
1191 | /* Similarly when the parent block ended in a SWITCH_EXPR. |
1192 | We can only know the value of the switch's condition if the dominator | |
1193 | parent is also the only predecessor of this block. */ | |
628f6a4e | 1194 | else if (EDGE_PRED (bb, 0)->src == parent |
6de9cd9a DN |
1195 | && TREE_CODE (parent_block_last_stmt) == SWITCH_EXPR) |
1196 | { | |
1197 | tree switch_cond = SWITCH_COND (parent_block_last_stmt); | |
1198 | ||
1199 | /* If the switch's condition is an SSA variable, then we may | |
1200 | know its value at each of the case labels. */ | |
1201 | if (TREE_CODE (switch_cond) == SSA_NAME) | |
1202 | { | |
1203 | tree switch_vec = SWITCH_LABELS (parent_block_last_stmt); | |
1204 | size_t i, n = TREE_VEC_LENGTH (switch_vec); | |
1205 | int case_count = 0; | |
1206 | tree match_case = NULL_TREE; | |
1207 | ||
1208 | /* Search the case labels for those whose destination is | |
1209 | the current basic block. */ | |
1210 | for (i = 0; i < n; ++i) | |
1211 | { | |
1212 | tree elt = TREE_VEC_ELT (switch_vec, i); | |
1213 | if (label_to_block (CASE_LABEL (elt)) == bb) | |
1214 | { | |
1c052514 | 1215 | if (++case_count > 1 || CASE_HIGH (elt)) |
6de9cd9a DN |
1216 | break; |
1217 | match_case = elt; | |
1218 | } | |
1219 | } | |
1220 | ||
1221 | /* If we encountered precisely one CASE_LABEL_EXPR and it | |
1222 | was not the default case, or a case range, then we know | |
1223 | the exact value of SWITCH_COND which caused us to get to | |
1224 | this block. Record that equivalence in EQ_EXPR_VALUE. */ | |
1225 | if (case_count == 1 | |
1c052514 | 1226 | && match_case |
6de9cd9a DN |
1227 | && CASE_LOW (match_case) |
1228 | && !CASE_HIGH (match_case)) | |
1229 | { | |
1230 | eq_expr_value.dst = switch_cond; | |
e9ea8bd5 RS |
1231 | eq_expr_value.src = fold_convert (TREE_TYPE (switch_cond), |
1232 | CASE_LOW (match_case)); | |
6de9cd9a DN |
1233 | } |
1234 | } | |
1235 | } | |
1236 | ||
1237 | /* If EQ_EXPR_VALUE (VAR == VALUE) is given, register the VALUE as a | |
1238 | new value for VAR, so that occurrences of VAR can be replaced with | |
1239 | VALUE while re-writing the THEN arm of a COND_EXPR. */ | |
1240 | if (eq_expr_value.src && eq_expr_value.dst) | |
b5fefcf6 | 1241 | record_equality (eq_expr_value.dst, eq_expr_value.src); |
6de9cd9a DN |
1242 | } |
1243 | ||
1244 | /* Dump SSA statistics on FILE. */ | |
1245 | ||
1246 | void | |
1247 | dump_dominator_optimization_stats (FILE *file) | |
1248 | { | |
1249 | long n_exprs; | |
1250 | ||
1251 | fprintf (file, "Total number of statements: %6ld\n\n", | |
1252 | opt_stats.num_stmts); | |
1253 | fprintf (file, "Exprs considered for dominator optimizations: %6ld\n", | |
1254 | opt_stats.num_exprs_considered); | |
1255 | ||
1256 | n_exprs = opt_stats.num_exprs_considered; | |
1257 | if (n_exprs == 0) | |
1258 | n_exprs = 1; | |
1259 | ||
1260 | fprintf (file, " Redundant expressions eliminated: %6ld (%.0f%%)\n", | |
1261 | opt_stats.num_re, PERCENT (opt_stats.num_re, | |
1262 | n_exprs)); | |
1263 | ||
1264 | fprintf (file, "\nHash table statistics:\n"); | |
1265 | ||
1266 | fprintf (file, " avail_exprs: "); | |
1267 | htab_statistics (file, avail_exprs); | |
1268 | } | |
1269 | ||
1270 | ||
1271 | /* Dump SSA statistics on stderr. */ | |
1272 | ||
1273 | void | |
1274 | debug_dominator_optimization_stats (void) | |
1275 | { | |
1276 | dump_dominator_optimization_stats (stderr); | |
1277 | } | |
1278 | ||
1279 | ||
1280 | /* Dump statistics for the hash table HTAB. */ | |
1281 | ||
1282 | static void | |
1283 | htab_statistics (FILE *file, htab_t htab) | |
1284 | { | |
1285 | fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n", | |
1286 | (long) htab_size (htab), | |
1287 | (long) htab_elements (htab), | |
1288 | htab_collisions (htab)); | |
1289 | } | |
1290 | ||
1291 | /* Record the fact that VAR has a nonzero value, though we may not know | |
1292 | its exact value. Note that if VAR is already known to have a nonzero | |
1293 | value, then we do nothing. */ | |
1294 | ||
1295 | static void | |
fdabe5c2 | 1296 | record_var_is_nonzero (tree var) |
6de9cd9a DN |
1297 | { |
1298 | int indx = SSA_NAME_VERSION (var); | |
1299 | ||
1300 | if (bitmap_bit_p (nonzero_vars, indx)) | |
1301 | return; | |
1302 | ||
1303 | /* Mark it in the global table. */ | |
1304 | bitmap_set_bit (nonzero_vars, indx); | |
1305 | ||
1306 | /* Record this SSA_NAME so that we can reset the global table | |
1307 | when we leave this block. */ | |
fdabe5c2 | 1308 | VARRAY_PUSH_TREE (nonzero_vars_stack, var); |
6de9cd9a DN |
1309 | } |
1310 | ||
1311 | /* Enter a statement into the true/false expression hash table indicating | |
1312 | that the condition COND has the value VALUE. */ | |
1313 | ||
1314 | static void | |
48732f23 | 1315 | record_cond (tree cond, tree value) |
6de9cd9a DN |
1316 | { |
1317 | struct expr_hash_elt *element = xmalloc (sizeof (struct expr_hash_elt)); | |
1318 | void **slot; | |
1319 | ||
1320 | initialize_hash_element (cond, value, element); | |
1321 | ||
1322 | slot = htab_find_slot_with_hash (avail_exprs, (void *)element, | |
1323 | element->hash, true); | |
1324 | if (*slot == NULL) | |
1325 | { | |
1326 | *slot = (void *) element; | |
48732f23 | 1327 | VARRAY_PUSH_TREE (avail_exprs_stack, cond); |
6de9cd9a DN |
1328 | } |
1329 | else | |
1330 | free (element); | |
1331 | } | |
1332 | ||
d2d8936f JL |
1333 | /* COND is a condition which is known to be true. Record variants of |
1334 | COND which must also be true. | |
1335 | ||
1336 | For example, if a < b is true, then a <= b must also be true. */ | |
1337 | ||
1338 | static void | |
48732f23 | 1339 | record_dominating_conditions (tree cond) |
d2d8936f JL |
1340 | { |
1341 | switch (TREE_CODE (cond)) | |
1342 | { | |
1343 | case LT_EXPR: | |
1344 | record_cond (build2 (LE_EXPR, boolean_type_node, | |
1345 | TREE_OPERAND (cond, 0), | |
1346 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1347 | boolean_true_node); |
d2d8936f JL |
1348 | record_cond (build2 (ORDERED_EXPR, boolean_type_node, |
1349 | TREE_OPERAND (cond, 0), | |
1350 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1351 | boolean_true_node); |
d2d8936f JL |
1352 | record_cond (build2 (NE_EXPR, boolean_type_node, |
1353 | TREE_OPERAND (cond, 0), | |
1354 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1355 | boolean_true_node); |
d2d8936f JL |
1356 | record_cond (build2 (LTGT_EXPR, boolean_type_node, |
1357 | TREE_OPERAND (cond, 0), | |
1358 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1359 | boolean_true_node); |
d2d8936f JL |
1360 | break; |
1361 | ||
1362 | case GT_EXPR: | |
1363 | record_cond (build2 (GE_EXPR, boolean_type_node, | |
1364 | TREE_OPERAND (cond, 0), | |
1365 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1366 | boolean_true_node); |
d2d8936f JL |
1367 | record_cond (build2 (ORDERED_EXPR, boolean_type_node, |
1368 | TREE_OPERAND (cond, 0), | |
1369 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1370 | boolean_true_node); |
d2d8936f JL |
1371 | record_cond (build2 (NE_EXPR, boolean_type_node, |
1372 | TREE_OPERAND (cond, 0), | |
1373 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1374 | boolean_true_node); |
d2d8936f JL |
1375 | record_cond (build2 (LTGT_EXPR, boolean_type_node, |
1376 | TREE_OPERAND (cond, 0), | |
1377 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1378 | boolean_true_node); |
d2d8936f JL |
1379 | break; |
1380 | ||
1381 | case GE_EXPR: | |
1382 | case LE_EXPR: | |
1383 | record_cond (build2 (ORDERED_EXPR, boolean_type_node, | |
1384 | TREE_OPERAND (cond, 0), | |
1385 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1386 | boolean_true_node); |
d2d8936f JL |
1387 | break; |
1388 | ||
1389 | case EQ_EXPR: | |
1390 | record_cond (build2 (ORDERED_EXPR, boolean_type_node, | |
1391 | TREE_OPERAND (cond, 0), | |
1392 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1393 | boolean_true_node); |
d2d8936f JL |
1394 | record_cond (build2 (LE_EXPR, boolean_type_node, |
1395 | TREE_OPERAND (cond, 0), | |
1396 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1397 | boolean_true_node); |
d2d8936f JL |
1398 | record_cond (build2 (GE_EXPR, boolean_type_node, |
1399 | TREE_OPERAND (cond, 0), | |
1400 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1401 | boolean_true_node); |
d2d8936f JL |
1402 | break; |
1403 | ||
1404 | case UNORDERED_EXPR: | |
1405 | record_cond (build2 (NE_EXPR, boolean_type_node, | |
1406 | TREE_OPERAND (cond, 0), | |
1407 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1408 | boolean_true_node); |
d2d8936f JL |
1409 | record_cond (build2 (UNLE_EXPR, boolean_type_node, |
1410 | TREE_OPERAND (cond, 0), | |
1411 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1412 | boolean_true_node); |
d2d8936f JL |
1413 | record_cond (build2 (UNGE_EXPR, boolean_type_node, |
1414 | TREE_OPERAND (cond, 0), | |
1415 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1416 | boolean_true_node); |
d2d8936f JL |
1417 | record_cond (build2 (UNEQ_EXPR, boolean_type_node, |
1418 | TREE_OPERAND (cond, 0), | |
1419 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1420 | boolean_true_node); |
d2d8936f JL |
1421 | record_cond (build2 (UNLT_EXPR, boolean_type_node, |
1422 | TREE_OPERAND (cond, 0), | |
1423 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1424 | boolean_true_node); |
d2d8936f JL |
1425 | record_cond (build2 (UNGT_EXPR, boolean_type_node, |
1426 | TREE_OPERAND (cond, 0), | |
1427 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1428 | boolean_true_node); |
d2d8936f JL |
1429 | break; |
1430 | ||
1431 | case UNLT_EXPR: | |
1432 | record_cond (build2 (UNLE_EXPR, boolean_type_node, | |
1433 | TREE_OPERAND (cond, 0), | |
1434 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1435 | boolean_true_node); |
d2d8936f JL |
1436 | record_cond (build2 (NE_EXPR, boolean_type_node, |
1437 | TREE_OPERAND (cond, 0), | |
1438 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1439 | boolean_true_node); |
d2d8936f JL |
1440 | break; |
1441 | ||
1442 | case UNGT_EXPR: | |
1443 | record_cond (build2 (UNGE_EXPR, boolean_type_node, | |
1444 | TREE_OPERAND (cond, 0), | |
1445 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1446 | boolean_true_node); |
d2d8936f JL |
1447 | record_cond (build2 (NE_EXPR, boolean_type_node, |
1448 | TREE_OPERAND (cond, 0), | |
1449 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1450 | boolean_true_node); |
d2d8936f JL |
1451 | break; |
1452 | ||
1453 | case UNEQ_EXPR: | |
1454 | record_cond (build2 (UNLE_EXPR, boolean_type_node, | |
1455 | TREE_OPERAND (cond, 0), | |
1456 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1457 | boolean_true_node); |
d2d8936f JL |
1458 | record_cond (build2 (UNGE_EXPR, boolean_type_node, |
1459 | TREE_OPERAND (cond, 0), | |
1460 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1461 | boolean_true_node); |
d2d8936f JL |
1462 | break; |
1463 | ||
1464 | case LTGT_EXPR: | |
1465 | record_cond (build2 (NE_EXPR, boolean_type_node, | |
1466 | TREE_OPERAND (cond, 0), | |
1467 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1468 | boolean_true_node); |
d2d8936f JL |
1469 | record_cond (build2 (ORDERED_EXPR, boolean_type_node, |
1470 | TREE_OPERAND (cond, 0), | |
1471 | TREE_OPERAND (cond, 1)), | |
48732f23 | 1472 | boolean_true_node); |
d2d8936f JL |
1473 | |
1474 | default: | |
1475 | break; | |
1476 | } | |
1477 | } | |
1478 | ||
6de9cd9a DN |
1479 | /* A helper function for record_const_or_copy and record_equality. |
1480 | Do the work of recording the value and undo info. */ | |
1481 | ||
1482 | static void | |
b5fefcf6 | 1483 | record_const_or_copy_1 (tree x, tree y, tree prev_x) |
6de9cd9a | 1484 | { |
3aecd08b | 1485 | SSA_NAME_VALUE (x) = y; |
6de9cd9a | 1486 | |
b5fefcf6 JL |
1487 | VARRAY_PUSH_TREE (const_and_copies_stack, prev_x); |
1488 | VARRAY_PUSH_TREE (const_and_copies_stack, x); | |
6de9cd9a DN |
1489 | } |
1490 | ||
1491 | /* Record that X is equal to Y in const_and_copies. Record undo | |
1492 | information in the block-local varray. */ | |
1493 | ||
1494 | static void | |
b5fefcf6 | 1495 | record_const_or_copy (tree x, tree y) |
6de9cd9a | 1496 | { |
3aecd08b | 1497 | tree prev_x = SSA_NAME_VALUE (x); |
6de9cd9a DN |
1498 | |
1499 | if (TREE_CODE (y) == SSA_NAME) | |
1500 | { | |
3aecd08b | 1501 | tree tmp = SSA_NAME_VALUE (y); |
6de9cd9a DN |
1502 | if (tmp) |
1503 | y = tmp; | |
1504 | } | |
1505 | ||
b5fefcf6 | 1506 | record_const_or_copy_1 (x, y, prev_x); |
6de9cd9a DN |
1507 | } |
1508 | ||
1509 | /* Similarly, but assume that X and Y are the two operands of an EQ_EXPR. | |
1510 | This constrains the cases in which we may treat this as assignment. */ | |
1511 | ||
1512 | static void | |
b5fefcf6 | 1513 | record_equality (tree x, tree y) |
6de9cd9a DN |
1514 | { |
1515 | tree prev_x = NULL, prev_y = NULL; | |
1516 | ||
1517 | if (TREE_CODE (x) == SSA_NAME) | |
3aecd08b | 1518 | prev_x = SSA_NAME_VALUE (x); |
6de9cd9a | 1519 | if (TREE_CODE (y) == SSA_NAME) |
3aecd08b | 1520 | prev_y = SSA_NAME_VALUE (y); |
6de9cd9a DN |
1521 | |
1522 | /* If one of the previous values is invariant, then use that. | |
1523 | Otherwise it doesn't matter which value we choose, just so | |
1524 | long as we canonicalize on one value. */ | |
1525 | if (TREE_INVARIANT (y)) | |
1526 | ; | |
1527 | else if (TREE_INVARIANT (x)) | |
1528 | prev_x = x, x = y, y = prev_x, prev_x = prev_y; | |
1529 | else if (prev_x && TREE_INVARIANT (prev_x)) | |
1530 | x = y, y = prev_x, prev_x = prev_y; | |
3aecd08b | 1531 | else if (prev_y && TREE_CODE (prev_y) != VALUE_HANDLE) |
6de9cd9a DN |
1532 | y = prev_y; |
1533 | ||
1534 | /* After the swapping, we must have one SSA_NAME. */ | |
1535 | if (TREE_CODE (x) != SSA_NAME) | |
1536 | return; | |
1537 | ||
1538 | /* For IEEE, -0.0 == 0.0, so we don't necessarily know the sign of a | |
1539 | variable compared against zero. If we're honoring signed zeros, | |
1540 | then we cannot record this value unless we know that the value is | |
1ea7e6ad | 1541 | nonzero. */ |
6de9cd9a DN |
1542 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (x))) |
1543 | && (TREE_CODE (y) != REAL_CST | |
1544 | || REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (y)))) | |
1545 | return; | |
1546 | ||
b5fefcf6 | 1547 | record_const_or_copy_1 (x, y, prev_x); |
6de9cd9a DN |
1548 | } |
1549 | ||
1550 | /* STMT is a MODIFY_EXPR for which we were unable to find RHS in the | |
1551 | hash tables. Try to simplify the RHS using whatever equivalences | |
1552 | we may have recorded. | |
1553 | ||
1554 | If we are able to simplify the RHS, then lookup the simplified form in | |
1555 | the hash table and return the result. Otherwise return NULL. */ | |
1556 | ||
1557 | static tree | |
1558 | simplify_rhs_and_lookup_avail_expr (struct dom_walk_data *walk_data, | |
68b9f53b | 1559 | tree stmt, int insert) |
6de9cd9a DN |
1560 | { |
1561 | tree rhs = TREE_OPERAND (stmt, 1); | |
1562 | enum tree_code rhs_code = TREE_CODE (rhs); | |
1563 | tree result = NULL; | |
6de9cd9a DN |
1564 | |
1565 | /* If we have lhs = ~x, look and see if we earlier had x = ~y. | |
1566 | In which case we can change this statement to be lhs = y. | |
1567 | Which can then be copy propagated. | |
1568 | ||
1569 | Similarly for negation. */ | |
1570 | if ((rhs_code == BIT_NOT_EXPR || rhs_code == NEGATE_EXPR) | |
1571 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME) | |
1572 | { | |
1573 | /* Get the definition statement for our RHS. */ | |
1574 | tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0)); | |
1575 | ||
1576 | /* See if the RHS_DEF_STMT has the same form as our statement. */ | |
1577 | if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR | |
1578 | && TREE_CODE (TREE_OPERAND (rhs_def_stmt, 1)) == rhs_code) | |
1579 | { | |
1580 | tree rhs_def_operand; | |
1581 | ||
1582 | rhs_def_operand = TREE_OPERAND (TREE_OPERAND (rhs_def_stmt, 1), 0); | |
1583 | ||
1584 | /* Verify that RHS_DEF_OPERAND is a suitable SSA variable. */ | |
1585 | if (TREE_CODE (rhs_def_operand) == SSA_NAME | |
1586 | && ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand)) | |
1587 | result = update_rhs_and_lookup_avail_expr (stmt, | |
1588 | rhs_def_operand, | |
6de9cd9a DN |
1589 | insert); |
1590 | } | |
1591 | } | |
1592 | ||
1593 | /* If we have z = (x OP C1), see if we earlier had x = y OP C2. | |
1594 | If OP is associative, create and fold (y OP C2) OP C1 which | |
1595 | should result in (y OP C3), use that as the RHS for the | |
1596 | assignment. Add minus to this, as we handle it specially below. */ | |
1597 | if ((associative_tree_code (rhs_code) || rhs_code == MINUS_EXPR) | |
1598 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME | |
1599 | && is_gimple_min_invariant (TREE_OPERAND (rhs, 1))) | |
1600 | { | |
1601 | tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0)); | |
1602 | ||
1603 | /* See if the RHS_DEF_STMT has the same form as our statement. */ | |
1604 | if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR) | |
1605 | { | |
1606 | tree rhs_def_rhs = TREE_OPERAND (rhs_def_stmt, 1); | |
1607 | enum tree_code rhs_def_code = TREE_CODE (rhs_def_rhs); | |
1608 | ||
1609 | if (rhs_code == rhs_def_code | |
1610 | || (rhs_code == PLUS_EXPR && rhs_def_code == MINUS_EXPR) | |
1611 | || (rhs_code == MINUS_EXPR && rhs_def_code == PLUS_EXPR)) | |
1612 | { | |
1613 | tree def_stmt_op0 = TREE_OPERAND (rhs_def_rhs, 0); | |
1614 | tree def_stmt_op1 = TREE_OPERAND (rhs_def_rhs, 1); | |
1615 | ||
1616 | if (TREE_CODE (def_stmt_op0) == SSA_NAME | |
1617 | && ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def_stmt_op0) | |
1618 | && is_gimple_min_invariant (def_stmt_op1)) | |
1619 | { | |
1620 | tree outer_const = TREE_OPERAND (rhs, 1); | |
1621 | tree type = TREE_TYPE (TREE_OPERAND (stmt, 0)); | |
1622 | tree t; | |
1623 | ||
f05ef422 RH |
1624 | /* If we care about correct floating point results, then |
1625 | don't fold x + c1 - c2. Note that we need to take both | |
1626 | the codes and the signs to figure this out. */ | |
1627 | if (FLOAT_TYPE_P (type) | |
1628 | && !flag_unsafe_math_optimizations | |
1629 | && (rhs_def_code == PLUS_EXPR | |
1630 | || rhs_def_code == MINUS_EXPR)) | |
1631 | { | |
1632 | bool neg = false; | |
1633 | ||
1634 | neg ^= (rhs_code == MINUS_EXPR); | |
1635 | neg ^= (rhs_def_code == MINUS_EXPR); | |
1636 | neg ^= real_isneg (TREE_REAL_CST_PTR (outer_const)); | |
1637 | neg ^= real_isneg (TREE_REAL_CST_PTR (def_stmt_op1)); | |
1638 | ||
1639 | if (neg) | |
1640 | goto dont_fold_assoc; | |
1641 | } | |
1642 | ||
6de9cd9a DN |
1643 | /* Ho hum. So fold will only operate on the outermost |
1644 | thingy that we give it, so we have to build the new | |
1645 | expression in two pieces. This requires that we handle | |
1646 | combinations of plus and minus. */ | |
1647 | if (rhs_def_code != rhs_code) | |
1648 | { | |
1649 | if (rhs_def_code == MINUS_EXPR) | |
1650 | t = build (MINUS_EXPR, type, outer_const, def_stmt_op1); | |
1651 | else | |
1652 | t = build (MINUS_EXPR, type, def_stmt_op1, outer_const); | |
1653 | rhs_code = PLUS_EXPR; | |
1654 | } | |
1655 | else if (rhs_def_code == MINUS_EXPR) | |
1656 | t = build (PLUS_EXPR, type, def_stmt_op1, outer_const); | |
1657 | else | |
1658 | t = build (rhs_def_code, type, def_stmt_op1, outer_const); | |
1659 | t = local_fold (t); | |
1660 | t = build (rhs_code, type, def_stmt_op0, t); | |
1661 | t = local_fold (t); | |
1662 | ||
1663 | /* If the result is a suitable looking gimple expression, | |
1664 | then use it instead of the original for STMT. */ | |
1665 | if (TREE_CODE (t) == SSA_NAME | |
6615c446 | 1666 | || (UNARY_CLASS_P (t) |
6de9cd9a | 1667 | && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME) |
6615c446 | 1668 | || ((BINARY_CLASS_P (t) || COMPARISON_CLASS_P (t)) |
6de9cd9a DN |
1669 | && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME |
1670 | && is_gimple_val (TREE_OPERAND (t, 1)))) | |
48732f23 | 1671 | result = update_rhs_and_lookup_avail_expr (stmt, t, insert); |
6de9cd9a DN |
1672 | } |
1673 | } | |
1674 | } | |
f05ef422 | 1675 | dont_fold_assoc:; |
6de9cd9a DN |
1676 | } |
1677 | ||
1678 | /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR | |
1679 | and BIT_AND_EXPR respectively if the first operand is greater | |
1680 | than zero and the second operand is an exact power of two. */ | |
1681 | if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR) | |
1682 | && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))) | |
1683 | && integer_pow2p (TREE_OPERAND (rhs, 1))) | |
1684 | { | |
1685 | tree val; | |
1686 | tree op = TREE_OPERAND (rhs, 0); | |
1687 | ||
1688 | if (TYPE_UNSIGNED (TREE_TYPE (op))) | |
1689 | { | |
1690 | val = integer_one_node; | |
1691 | } | |
1692 | else | |
1693 | { | |
1694 | tree dummy_cond = walk_data->global_data; | |
1695 | ||
1696 | if (! dummy_cond) | |
1697 | { | |
1698 | dummy_cond = build (GT_EXPR, boolean_type_node, | |
1699 | op, integer_zero_node); | |
1700 | dummy_cond = build (COND_EXPR, void_type_node, | |
1701 | dummy_cond, NULL, NULL); | |
1702 | walk_data->global_data = dummy_cond; | |
1703 | } | |
1704 | else | |
1705 | { | |
1706 | TREE_SET_CODE (TREE_OPERAND (dummy_cond, 0), GT_EXPR); | |
1707 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 0) = op; | |
1708 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 1) | |
1709 | = integer_zero_node; | |
1710 | } | |
48732f23 | 1711 | val = simplify_cond_and_lookup_avail_expr (dummy_cond, NULL, false); |
6de9cd9a DN |
1712 | } |
1713 | ||
1714 | if (val && integer_onep (val)) | |
1715 | { | |
1716 | tree t; | |
1717 | tree op0 = TREE_OPERAND (rhs, 0); | |
1718 | tree op1 = TREE_OPERAND (rhs, 1); | |
1719 | ||
1720 | if (rhs_code == TRUNC_DIV_EXPR) | |
1721 | t = build (RSHIFT_EXPR, TREE_TYPE (op0), op0, | |
7d60be94 | 1722 | build_int_cst (NULL_TREE, tree_log2 (op1))); |
6de9cd9a DN |
1723 | else |
1724 | t = build (BIT_AND_EXPR, TREE_TYPE (op0), op0, | |
1725 | local_fold (build (MINUS_EXPR, TREE_TYPE (op1), | |
1726 | op1, integer_one_node))); | |
1727 | ||
48732f23 | 1728 | result = update_rhs_and_lookup_avail_expr (stmt, t, insert); |
6de9cd9a DN |
1729 | } |
1730 | } | |
1731 | ||
1732 | /* Transform ABS (X) into X or -X as appropriate. */ | |
1733 | if (rhs_code == ABS_EXPR | |
1734 | && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))) | |
1735 | { | |
1736 | tree val; | |
1737 | tree op = TREE_OPERAND (rhs, 0); | |
1738 | tree type = TREE_TYPE (op); | |
1739 | ||
1740 | if (TYPE_UNSIGNED (type)) | |
1741 | { | |
1742 | val = integer_zero_node; | |
1743 | } | |
1744 | else | |
1745 | { | |
1746 | tree dummy_cond = walk_data->global_data; | |
1747 | ||
1748 | if (! dummy_cond) | |
1749 | { | |
14bc8dc2 | 1750 | dummy_cond = build (LE_EXPR, boolean_type_node, |
6de9cd9a DN |
1751 | op, integer_zero_node); |
1752 | dummy_cond = build (COND_EXPR, void_type_node, | |
1753 | dummy_cond, NULL, NULL); | |
1754 | walk_data->global_data = dummy_cond; | |
1755 | } | |
1756 | else | |
1757 | { | |
14bc8dc2 | 1758 | TREE_SET_CODE (TREE_OPERAND (dummy_cond, 0), LE_EXPR); |
6de9cd9a DN |
1759 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 0) = op; |
1760 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 1) | |
5212068f | 1761 | = build_int_cst (type, 0); |
6de9cd9a | 1762 | } |
48732f23 | 1763 | val = simplify_cond_and_lookup_avail_expr (dummy_cond, NULL, false); |
14bc8dc2 JL |
1764 | |
1765 | if (!val) | |
1766 | { | |
1767 | TREE_SET_CODE (TREE_OPERAND (dummy_cond, 0), GE_EXPR); | |
1768 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 0) = op; | |
1769 | TREE_OPERAND (TREE_OPERAND (dummy_cond, 0), 1) | |
5212068f | 1770 | = build_int_cst (type, 0); |
14bc8dc2 JL |
1771 | |
1772 | val = simplify_cond_and_lookup_avail_expr (dummy_cond, | |
14bc8dc2 JL |
1773 | NULL, false); |
1774 | ||
1775 | if (val) | |
1776 | { | |
1777 | if (integer_zerop (val)) | |
1778 | val = integer_one_node; | |
1779 | else if (integer_onep (val)) | |
1780 | val = integer_zero_node; | |
1781 | } | |
1782 | } | |
6de9cd9a DN |
1783 | } |
1784 | ||
1785 | if (val | |
1786 | && (integer_onep (val) || integer_zerop (val))) | |
1787 | { | |
1788 | tree t; | |
1789 | ||
1790 | if (integer_onep (val)) | |
1791 | t = build1 (NEGATE_EXPR, TREE_TYPE (op), op); | |
1792 | else | |
1793 | t = op; | |
1794 | ||
48732f23 | 1795 | result = update_rhs_and_lookup_avail_expr (stmt, t, insert); |
6de9cd9a DN |
1796 | } |
1797 | } | |
1798 | ||
1799 | /* Optimize *"foo" into 'f'. This is done here rather than | |
1800 | in fold to avoid problems with stuff like &*"foo". */ | |
1801 | if (TREE_CODE (rhs) == INDIRECT_REF || TREE_CODE (rhs) == ARRAY_REF) | |
1802 | { | |
1803 | tree t = fold_read_from_constant_string (rhs); | |
1804 | ||
1805 | if (t) | |
48732f23 | 1806 | result = update_rhs_and_lookup_avail_expr (stmt, t, insert); |
6de9cd9a DN |
1807 | } |
1808 | ||
1809 | return result; | |
1810 | } | |
1811 | ||
1812 | /* COND is a condition of the form: | |
1813 | ||
1814 | x == const or x != const | |
1815 | ||
1816 | Look back to x's defining statement and see if x is defined as | |
1817 | ||
1818 | x = (type) y; | |
1819 | ||
1820 | If const is unchanged if we convert it to type, then we can build | |
1821 | the equivalent expression: | |
1822 | ||
1823 | ||
1824 | y == const or y != const | |
1825 | ||
1826 | Which may allow further optimizations. | |
1827 | ||
1828 | Return the equivalent comparison or NULL if no such equivalent comparison | |
1829 | was found. */ | |
1830 | ||
1831 | static tree | |
1832 | find_equivalent_equality_comparison (tree cond) | |
1833 | { | |
1834 | tree op0 = TREE_OPERAND (cond, 0); | |
1835 | tree op1 = TREE_OPERAND (cond, 1); | |
1836 | tree def_stmt = SSA_NAME_DEF_STMT (op0); | |
1837 | ||
1838 | /* OP0 might have been a parameter, so first make sure it | |
1839 | was defined by a MODIFY_EXPR. */ | |
1840 | if (def_stmt && TREE_CODE (def_stmt) == MODIFY_EXPR) | |
1841 | { | |
1842 | tree def_rhs = TREE_OPERAND (def_stmt, 1); | |
1843 | ||
1844 | /* Now make sure the RHS of the MODIFY_EXPR is a typecast. */ | |
1845 | if ((TREE_CODE (def_rhs) == NOP_EXPR | |
1846 | || TREE_CODE (def_rhs) == CONVERT_EXPR) | |
1847 | && TREE_CODE (TREE_OPERAND (def_rhs, 0)) == SSA_NAME) | |
1848 | { | |
1849 | tree def_rhs_inner = TREE_OPERAND (def_rhs, 0); | |
1850 | tree def_rhs_inner_type = TREE_TYPE (def_rhs_inner); | |
1851 | tree new; | |
1852 | ||
1853 | if (TYPE_PRECISION (def_rhs_inner_type) | |
1854 | > TYPE_PRECISION (TREE_TYPE (def_rhs))) | |
1855 | return NULL; | |
1856 | ||
1857 | /* What we want to prove is that if we convert OP1 to | |
1858 | the type of the object inside the NOP_EXPR that the | |
1859 | result is still equivalent to SRC. | |
1860 | ||
1861 | If that is true, the build and return new equivalent | |
1862 | condition which uses the source of the typecast and the | |
1863 | new constant (which has only changed its type). */ | |
1864 | new = build1 (TREE_CODE (def_rhs), def_rhs_inner_type, op1); | |
1865 | new = local_fold (new); | |
1866 | if (is_gimple_val (new) && tree_int_cst_equal (new, op1)) | |
1867 | return build (TREE_CODE (cond), TREE_TYPE (cond), | |
1868 | def_rhs_inner, new); | |
1869 | } | |
1870 | } | |
1871 | return NULL; | |
1872 | } | |
1873 | ||
1874 | /* STMT is a COND_EXPR for which we could not trivially determine its | |
1875 | result. This routine attempts to find equivalent forms of the | |
1876 | condition which we may be able to optimize better. It also | |
1877 | uses simple value range propagation to optimize conditionals. */ | |
1878 | ||
1879 | static tree | |
1880 | simplify_cond_and_lookup_avail_expr (tree stmt, | |
6de9cd9a DN |
1881 | stmt_ann_t ann, |
1882 | int insert) | |
1883 | { | |
1884 | tree cond = COND_EXPR_COND (stmt); | |
1885 | ||
6615c446 | 1886 | if (COMPARISON_CLASS_P (cond)) |
6de9cd9a DN |
1887 | { |
1888 | tree op0 = TREE_OPERAND (cond, 0); | |
1889 | tree op1 = TREE_OPERAND (cond, 1); | |
1890 | ||
1891 | if (TREE_CODE (op0) == SSA_NAME && is_gimple_min_invariant (op1)) | |
1892 | { | |
1893 | int limit; | |
1894 | tree low, high, cond_low, cond_high; | |
1895 | int lowequal, highequal, swapped, no_overlap, subset, cond_inverted; | |
1896 | varray_type vrp_records; | |
1897 | struct vrp_element *element; | |
b8545fbf | 1898 | struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p; |
23530866 | 1899 | void **slot; |
6de9cd9a DN |
1900 | |
1901 | /* First see if we have test of an SSA_NAME against a constant | |
1902 | where the SSA_NAME is defined by an earlier typecast which | |
1903 | is irrelevant when performing tests against the given | |
1904 | constant. */ | |
1905 | if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR) | |
1906 | { | |
1907 | tree new_cond = find_equivalent_equality_comparison (cond); | |
1908 | ||
1909 | if (new_cond) | |
1910 | { | |
1911 | /* Update the statement to use the new equivalent | |
1912 | condition. */ | |
1913 | COND_EXPR_COND (stmt) = new_cond; | |
68b9f53b AM |
1914 | |
1915 | /* If this is not a real stmt, ann will be NULL and we | |
1916 | avoid processing the operands. */ | |
1917 | if (ann) | |
1918 | modify_stmt (stmt); | |
6de9cd9a DN |
1919 | |
1920 | /* Lookup the condition and return its known value if it | |
1921 | exists. */ | |
48732f23 | 1922 | new_cond = lookup_avail_expr (stmt, insert); |
6de9cd9a DN |
1923 | if (new_cond) |
1924 | return new_cond; | |
1925 | ||
1926 | /* The operands have changed, so update op0 and op1. */ | |
1927 | op0 = TREE_OPERAND (cond, 0); | |
1928 | op1 = TREE_OPERAND (cond, 1); | |
1929 | } | |
1930 | } | |
1931 | ||
1932 | /* Consult the value range records for this variable (if they exist) | |
1933 | to see if we can eliminate or simplify this conditional. | |
1934 | ||
1935 | Note two tests are necessary to determine no records exist. | |
1936 | First we have to see if the virtual array exists, if it | |
1937 | exists, then we have to check its active size. | |
1938 | ||
1939 | Also note the vast majority of conditionals are not testing | |
1940 | a variable which has had its range constrained by an earlier | |
1941 | conditional. So this filter avoids a lot of unnecessary work. */ | |
23530866 JL |
1942 | vrp_hash_elt.var = op0; |
1943 | vrp_hash_elt.records = NULL; | |
1944 | slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT); | |
1945 | if (slot == NULL) | |
1946 | return NULL; | |
1947 | ||
b8545fbf JL |
1948 | vrp_hash_elt_p = (struct vrp_hash_elt *) *slot; |
1949 | vrp_records = vrp_hash_elt_p->records; | |
6de9cd9a DN |
1950 | if (vrp_records == NULL) |
1951 | return NULL; | |
1952 | ||
1953 | limit = VARRAY_ACTIVE_SIZE (vrp_records); | |
1954 | ||
1955 | /* If we have no value range records for this variable, or we are | |
1956 | unable to extract a range for this condition, then there is | |
1957 | nothing to do. */ | |
1958 | if (limit == 0 | |
1959 | || ! extract_range_from_cond (cond, &cond_high, | |
1960 | &cond_low, &cond_inverted)) | |
1961 | return NULL; | |
1962 | ||
1963 | /* We really want to avoid unnecessary computations of range | |
1964 | info. So all ranges are computed lazily; this avoids a | |
454ff5cb | 1965 | lot of unnecessary work. i.e., we record the conditional, |
6de9cd9a DN |
1966 | but do not process how it constrains the variable's |
1967 | potential values until we know that processing the condition | |
1968 | could be helpful. | |
1969 | ||
1970 | However, we do not want to have to walk a potentially long | |
1971 | list of ranges, nor do we want to compute a variable's | |
1972 | range more than once for a given path. | |
1973 | ||
1974 | Luckily, each time we encounter a conditional that can not | |
1975 | be otherwise optimized we will end up here and we will | |
1976 | compute the necessary range information for the variable | |
1977 | used in this condition. | |
1978 | ||
1979 | Thus you can conclude that there will never be more than one | |
1980 | conditional associated with a variable which has not been | |
1981 | processed. So we never need to merge more than one new | |
1982 | conditional into the current range. | |
1983 | ||
1984 | These properties also help us avoid unnecessary work. */ | |
1985 | element | |
1986 | = (struct vrp_element *)VARRAY_GENERIC_PTR (vrp_records, limit - 1); | |
1987 | ||
1988 | if (element->high && element->low) | |
1989 | { | |
1990 | /* The last element has been processed, so there is no range | |
1991 | merging to do, we can simply use the high/low values | |
1992 | recorded in the last element. */ | |
1993 | low = element->low; | |
1994 | high = element->high; | |
1995 | } | |
1996 | else | |
1997 | { | |
1998 | tree tmp_high, tmp_low; | |
1999 | int dummy; | |
2000 | ||
2001 | /* The last element has not been processed. Process it now. */ | |
2002 | extract_range_from_cond (element->cond, &tmp_high, | |
2003 | &tmp_low, &dummy); | |
2004 | ||
2005 | /* If this is the only element, then no merging is necessary, | |
2006 | the high/low values from extract_range_from_cond are all | |
2007 | we need. */ | |
2008 | if (limit == 1) | |
2009 | { | |
2010 | low = tmp_low; | |
2011 | high = tmp_high; | |
2012 | } | |
2013 | else | |
2014 | { | |
2015 | /* Get the high/low value from the previous element. */ | |
2016 | struct vrp_element *prev | |
2017 | = (struct vrp_element *)VARRAY_GENERIC_PTR (vrp_records, | |
2018 | limit - 2); | |
2019 | low = prev->low; | |
2020 | high = prev->high; | |
2021 | ||
2022 | /* Merge in this element's range with the range from the | |
2023 | previous element. | |
2024 | ||
2025 | The low value for the merged range is the maximum of | |
2026 | the previous low value and the low value of this record. | |
2027 | ||
2028 | Similarly the high value for the merged range is the | |
2029 | minimum of the previous high value and the high value of | |
2030 | this record. */ | |
2031 | low = (tree_int_cst_compare (low, tmp_low) == 1 | |
2032 | ? low : tmp_low); | |
2033 | high = (tree_int_cst_compare (high, tmp_high) == -1 | |
2034 | ? high : tmp_high); | |
2035 | } | |
2036 | ||
2037 | /* And record the computed range. */ | |
2038 | element->low = low; | |
2039 | element->high = high; | |
2040 | ||
2041 | } | |
2042 | ||
2043 | /* After we have constrained this variable's potential values, | |
2044 | we try to determine the result of the given conditional. | |
2045 | ||
2046 | To simplify later tests, first determine if the current | |
2047 | low value is the same low value as the conditional. | |
2048 | Similarly for the current high value and the high value | |
2049 | for the conditional. */ | |
2050 | lowequal = tree_int_cst_equal (low, cond_low); | |
2051 | highequal = tree_int_cst_equal (high, cond_high); | |
2052 | ||
2053 | if (lowequal && highequal) | |
2054 | return (cond_inverted ? boolean_false_node : boolean_true_node); | |
2055 | ||
2056 | /* To simplify the overlap/subset tests below we may want | |
2057 | to swap the two ranges so that the larger of the two | |
2058 | ranges occurs "first". */ | |
2059 | swapped = 0; | |
2060 | if (tree_int_cst_compare (low, cond_low) == 1 | |
2061 | || (lowequal | |
2062 | && tree_int_cst_compare (cond_high, high) == 1)) | |
2063 | { | |
2064 | tree temp; | |
2065 | ||
2066 | swapped = 1; | |
2067 | temp = low; | |
2068 | low = cond_low; | |
2069 | cond_low = temp; | |
2070 | temp = high; | |
2071 | high = cond_high; | |
2072 | cond_high = temp; | |
2073 | } | |
2074 | ||
2075 | /* Now determine if there is no overlap in the ranges | |
2076 | or if the second range is a subset of the first range. */ | |
2077 | no_overlap = tree_int_cst_lt (high, cond_low); | |
2078 | subset = tree_int_cst_compare (cond_high, high) != 1; | |
2079 | ||
2080 | /* If there was no overlap in the ranges, then this conditional | |
2081 | always has a false value (unless we had to invert this | |
2082 | conditional, in which case it always has a true value). */ | |
2083 | if (no_overlap) | |
2084 | return (cond_inverted ? boolean_true_node : boolean_false_node); | |
2085 | ||
2086 | /* If the current range is a subset of the condition's range, | |
2087 | then this conditional always has a true value (unless we | |
2088 | had to invert this conditional, in which case it always | |
2089 | has a true value). */ | |
2090 | if (subset && swapped) | |
2091 | return (cond_inverted ? boolean_false_node : boolean_true_node); | |
2092 | ||
2093 | /* We were unable to determine the result of the conditional. | |
2094 | However, we may be able to simplify the conditional. First | |
2095 | merge the ranges in the same manner as range merging above. */ | |
2096 | low = tree_int_cst_compare (low, cond_low) == 1 ? low : cond_low; | |
2097 | high = tree_int_cst_compare (high, cond_high) == -1 ? high : cond_high; | |
2098 | ||
2099 | /* If the range has converged to a single point, then turn this | |
2100 | into an equality comparison. */ | |
2101 | if (TREE_CODE (cond) != EQ_EXPR | |
2102 | && TREE_CODE (cond) != NE_EXPR | |
2103 | && tree_int_cst_equal (low, high)) | |
2104 | { | |
2105 | TREE_SET_CODE (cond, EQ_EXPR); | |
2106 | TREE_OPERAND (cond, 1) = high; | |
2107 | } | |
2108 | } | |
2109 | } | |
2110 | return 0; | |
2111 | } | |
2112 | ||
2113 | /* STMT is a SWITCH_EXPR for which we could not trivially determine its | |
2114 | result. This routine attempts to find equivalent forms of the | |
2115 | condition which we may be able to optimize better. */ | |
2116 | ||
2117 | static tree | |
48732f23 | 2118 | simplify_switch_and_lookup_avail_expr (tree stmt, int insert) |
6de9cd9a DN |
2119 | { |
2120 | tree cond = SWITCH_COND (stmt); | |
2121 | tree def, to, ti; | |
2122 | ||
2123 | /* The optimization that we really care about is removing unnecessary | |
2124 | casts. That will let us do much better in propagating the inferred | |
2125 | constant at the switch target. */ | |
2126 | if (TREE_CODE (cond) == SSA_NAME) | |
2127 | { | |
2128 | def = SSA_NAME_DEF_STMT (cond); | |
2129 | if (TREE_CODE (def) == MODIFY_EXPR) | |
2130 | { | |
2131 | def = TREE_OPERAND (def, 1); | |
2132 | if (TREE_CODE (def) == NOP_EXPR) | |
2133 | { | |
d969ee71 RH |
2134 | int need_precision; |
2135 | bool fail; | |
2136 | ||
6de9cd9a | 2137 | def = TREE_OPERAND (def, 0); |
d969ee71 RH |
2138 | |
2139 | #ifdef ENABLE_CHECKING | |
2140 | /* ??? Why was Jeff testing this? We are gimple... */ | |
1e128c5f | 2141 | gcc_assert (is_gimple_val (def)); |
d969ee71 RH |
2142 | #endif |
2143 | ||
6de9cd9a DN |
2144 | to = TREE_TYPE (cond); |
2145 | ti = TREE_TYPE (def); | |
2146 | ||
d969ee71 | 2147 | /* If we have an extension that preserves value, then we |
6de9cd9a | 2148 | can copy the source value into the switch. */ |
d969ee71 RH |
2149 | |
2150 | need_precision = TYPE_PRECISION (ti); | |
2151 | fail = false; | |
2152 | if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti)) | |
2153 | fail = true; | |
2154 | else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti)) | |
2155 | need_precision += 1; | |
2156 | if (TYPE_PRECISION (to) < need_precision) | |
2157 | fail = true; | |
2158 | ||
2159 | if (!fail) | |
6de9cd9a DN |
2160 | { |
2161 | SWITCH_COND (stmt) = def; | |
68b9f53b | 2162 | modify_stmt (stmt); |
6de9cd9a | 2163 | |
48732f23 | 2164 | return lookup_avail_expr (stmt, insert); |
6de9cd9a DN |
2165 | } |
2166 | } | |
2167 | } | |
2168 | } | |
2169 | ||
2170 | return 0; | |
2171 | } | |
2172 | ||
ff2ad0f7 DN |
2173 | |
2174 | /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current | |
2175 | known value for that SSA_NAME (or NULL if no value is known). | |
2176 | ||
2177 | NONZERO_VARS is the set SSA_NAMES known to have a nonzero value, | |
2178 | even if we don't know their precise value. | |
2179 | ||
2180 | Propagate values from CONST_AND_COPIES and NONZERO_VARS into the PHI | |
2181 | nodes of the successors of BB. */ | |
2182 | ||
2183 | static void | |
6f2aec07 | 2184 | cprop_into_successor_phis (basic_block bb, bitmap nonzero_vars) |
ff2ad0f7 DN |
2185 | { |
2186 | edge e; | |
628f6a4e | 2187 | edge_iterator ei; |
ff2ad0f7 DN |
2188 | |
2189 | /* This can get rather expensive if the implementation is naive in | |
2190 | how it finds the phi alternative associated with a particular edge. */ | |
628f6a4e | 2191 | FOR_EACH_EDGE (e, ei, bb->succs) |
ff2ad0f7 DN |
2192 | { |
2193 | tree phi; | |
2194 | int phi_num_args; | |
2195 | int hint; | |
2196 | ||
2197 | /* If this is an abnormal edge, then we do not want to copy propagate | |
2198 | into the PHI alternative associated with this edge. */ | |
2199 | if (e->flags & EDGE_ABNORMAL) | |
2200 | continue; | |
2201 | ||
2202 | phi = phi_nodes (e->dest); | |
2203 | if (! phi) | |
2204 | continue; | |
2205 | ||
2206 | /* There is no guarantee that for any two PHI nodes in a block that | |
2207 | the phi alternative associated with a particular edge will be | |
2208 | at the same index in the phi alternative array. | |
2209 | ||
2210 | However, it is very likely they will be the same. So we keep | |
2211 | track of the index of the alternative where we found the edge in | |
2212 | the previous phi node and check that index first in the next | |
2213 | phi node. If that hint fails, then we actually search all | |
2214 | the entries. */ | |
2215 | phi_num_args = PHI_NUM_ARGS (phi); | |
2216 | hint = phi_num_args; | |
2217 | for ( ; phi; phi = PHI_CHAIN (phi)) | |
2218 | { | |
2219 | int i; | |
2220 | tree new; | |
2221 | use_operand_p orig_p; | |
2222 | tree orig; | |
2223 | ||
2224 | /* If the hint is valid (!= phi_num_args), see if it points | |
2225 | us to the desired phi alternative. */ | |
2226 | if (hint != phi_num_args && PHI_ARG_EDGE (phi, hint) == e) | |
2227 | ; | |
2228 | else | |
2229 | { | |
2230 | /* The hint was either invalid or did not point to the | |
2231 | correct phi alternative. Search all the alternatives | |
2232 | for the correct one. Update the hint. */ | |
2233 | for (i = 0; i < phi_num_args; i++) | |
2234 | if (PHI_ARG_EDGE (phi, i) == e) | |
2235 | break; | |
2236 | hint = i; | |
2237 | } | |
2238 | ||
ff2ad0f7 DN |
2239 | /* If we did not find the proper alternative, then something is |
2240 | horribly wrong. */ | |
1e128c5f | 2241 | gcc_assert (hint != phi_num_args); |
ff2ad0f7 DN |
2242 | |
2243 | /* The alternative may be associated with a constant, so verify | |
2244 | it is an SSA_NAME before doing anything with it. */ | |
2245 | orig_p = PHI_ARG_DEF_PTR (phi, hint); | |
2246 | orig = USE_FROM_PTR (orig_p); | |
2247 | if (TREE_CODE (orig) != SSA_NAME) | |
2248 | continue; | |
2249 | ||
2250 | /* If the alternative is known to have a nonzero value, record | |
2251 | that fact in the PHI node itself for future use. */ | |
2252 | if (bitmap_bit_p (nonzero_vars, SSA_NAME_VERSION (orig))) | |
2253 | PHI_ARG_NONZERO (phi, hint) = true; | |
2254 | ||
2255 | /* If we have *ORIG_P in our constant/copy table, then replace | |
2256 | ORIG_P with its value in our constant/copy table. */ | |
3aecd08b | 2257 | new = SSA_NAME_VALUE (orig); |
ff2ad0f7 DN |
2258 | if (new |
2259 | && (TREE_CODE (new) == SSA_NAME | |
2260 | || is_gimple_min_invariant (new)) | |
2261 | && may_propagate_copy (orig, new)) | |
2262 | { | |
2263 | propagate_value (orig_p, new); | |
2264 | } | |
2265 | } | |
2266 | } | |
2267 | } | |
2268 | ||
2269 | ||
6de9cd9a DN |
2270 | /* Propagate known constants/copies into PHI nodes of BB's successor |
2271 | blocks. */ | |
2272 | ||
2273 | static void | |
2274 | cprop_into_phis (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
2275 | basic_block bb) | |
2276 | { | |
6f2aec07 | 2277 | cprop_into_successor_phis (bb, nonzero_vars); |
6de9cd9a DN |
2278 | } |
2279 | ||
2280 | /* Search for redundant computations in STMT. If any are found, then | |
2281 | replace them with the variable holding the result of the computation. | |
2282 | ||
2283 | If safe, record this expression into the available expression hash | |
2284 | table. */ | |
2285 | ||
2286 | static bool | |
2287 | eliminate_redundant_computations (struct dom_walk_data *walk_data, | |
2288 | tree stmt, stmt_ann_t ann) | |
2289 | { | |
a32b97a2 | 2290 | v_may_def_optype v_may_defs = V_MAY_DEF_OPS (ann); |
6de9cd9a DN |
2291 | tree *expr_p, def = NULL_TREE; |
2292 | bool insert = true; | |
2293 | tree cached_lhs; | |
2294 | bool retval = false; | |
6de9cd9a DN |
2295 | |
2296 | if (TREE_CODE (stmt) == MODIFY_EXPR) | |
2297 | def = TREE_OPERAND (stmt, 0); | |
2298 | ||
2299 | /* Certain expressions on the RHS can be optimized away, but can not | |
2300 | themselves be entered into the hash tables. */ | |
2301 | if (ann->makes_aliased_stores | |
2302 | || ! def | |
2303 | || TREE_CODE (def) != SSA_NAME | |
2304 | || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def) | |
a32b97a2 | 2305 | || NUM_V_MAY_DEFS (v_may_defs) != 0) |
6de9cd9a DN |
2306 | insert = false; |
2307 | ||
2308 | /* Check if the expression has been computed before. */ | |
48732f23 | 2309 | cached_lhs = lookup_avail_expr (stmt, insert); |
6de9cd9a DN |
2310 | |
2311 | /* If this is an assignment and the RHS was not in the hash table, | |
2312 | then try to simplify the RHS and lookup the new RHS in the | |
2313 | hash table. */ | |
2314 | if (! cached_lhs && TREE_CODE (stmt) == MODIFY_EXPR) | |
48732f23 | 2315 | cached_lhs = simplify_rhs_and_lookup_avail_expr (walk_data, stmt, insert); |
6de9cd9a DN |
2316 | /* Similarly if this is a COND_EXPR and we did not find its |
2317 | expression in the hash table, simplify the condition and | |
2318 | try again. */ | |
2319 | else if (! cached_lhs && TREE_CODE (stmt) == COND_EXPR) | |
48732f23 | 2320 | cached_lhs = simplify_cond_and_lookup_avail_expr (stmt, ann, insert); |
6de9cd9a DN |
2321 | /* Similarly for a SWITCH_EXPR. */ |
2322 | else if (!cached_lhs && TREE_CODE (stmt) == SWITCH_EXPR) | |
48732f23 | 2323 | cached_lhs = simplify_switch_and_lookup_avail_expr (stmt, insert); |
6de9cd9a DN |
2324 | |
2325 | opt_stats.num_exprs_considered++; | |
2326 | ||
2327 | /* Get a pointer to the expression we are trying to optimize. */ | |
2328 | if (TREE_CODE (stmt) == COND_EXPR) | |
2329 | expr_p = &COND_EXPR_COND (stmt); | |
2330 | else if (TREE_CODE (stmt) == SWITCH_EXPR) | |
2331 | expr_p = &SWITCH_COND (stmt); | |
2332 | else if (TREE_CODE (stmt) == RETURN_EXPR && TREE_OPERAND (stmt, 0)) | |
2333 | expr_p = &TREE_OPERAND (TREE_OPERAND (stmt, 0), 1); | |
2334 | else | |
2335 | expr_p = &TREE_OPERAND (stmt, 1); | |
2336 | ||
2337 | /* It is safe to ignore types here since we have already done | |
2338 | type checking in the hashing and equality routines. In fact | |
2339 | type checking here merely gets in the way of constant | |
2340 | propagation. Also, make sure that it is safe to propagate | |
2341 | CACHED_LHS into *EXPR_P. */ | |
2342 | if (cached_lhs | |
2343 | && (TREE_CODE (cached_lhs) != SSA_NAME | |
ff2ad0f7 | 2344 | || may_propagate_copy (*expr_p, cached_lhs))) |
6de9cd9a DN |
2345 | { |
2346 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2347 | { | |
2348 | fprintf (dump_file, " Replaced redundant expr '"); | |
2349 | print_generic_expr (dump_file, *expr_p, dump_flags); | |
2350 | fprintf (dump_file, "' with '"); | |
2351 | print_generic_expr (dump_file, cached_lhs, dump_flags); | |
2352 | fprintf (dump_file, "'\n"); | |
2353 | } | |
2354 | ||
2355 | opt_stats.num_re++; | |
2356 | ||
2357 | #if defined ENABLE_CHECKING | |
1e128c5f GB |
2358 | gcc_assert (TREE_CODE (cached_lhs) == SSA_NAME |
2359 | || is_gimple_min_invariant (cached_lhs)); | |
6de9cd9a DN |
2360 | #endif |
2361 | ||
2362 | if (TREE_CODE (cached_lhs) == ADDR_EXPR | |
2363 | || (POINTER_TYPE_P (TREE_TYPE (*expr_p)) | |
2364 | && is_gimple_min_invariant (cached_lhs))) | |
2365 | retval = true; | |
2366 | ||
d00ad49b | 2367 | propagate_tree_value (expr_p, cached_lhs); |
68b9f53b | 2368 | modify_stmt (stmt); |
6de9cd9a DN |
2369 | } |
2370 | return retval; | |
2371 | } | |
2372 | ||
2373 | /* STMT, a MODIFY_EXPR, may create certain equivalences, in either | |
2374 | the available expressions table or the const_and_copies table. | |
2375 | Detect and record those equivalences. */ | |
2376 | ||
2377 | static void | |
2378 | record_equivalences_from_stmt (tree stmt, | |
6de9cd9a DN |
2379 | int may_optimize_p, |
2380 | stmt_ann_t ann) | |
2381 | { | |
2382 | tree lhs = TREE_OPERAND (stmt, 0); | |
2383 | enum tree_code lhs_code = TREE_CODE (lhs); | |
2384 | int i; | |
2385 | ||
2386 | if (lhs_code == SSA_NAME) | |
2387 | { | |
2388 | tree rhs = TREE_OPERAND (stmt, 1); | |
2389 | ||
2390 | /* Strip away any useless type conversions. */ | |
2391 | STRIP_USELESS_TYPE_CONVERSION (rhs); | |
2392 | ||
2393 | /* If the RHS of the assignment is a constant or another variable that | |
2394 | may be propagated, register it in the CONST_AND_COPIES table. We | |
2395 | do not need to record unwind data for this, since this is a true | |
1ea7e6ad | 2396 | assignment and not an equivalence inferred from a comparison. All |
6de9cd9a DN |
2397 | uses of this ssa name are dominated by this assignment, so unwinding |
2398 | just costs time and space. */ | |
2399 | if (may_optimize_p | |
2400 | && (TREE_CODE (rhs) == SSA_NAME | |
2401 | || is_gimple_min_invariant (rhs))) | |
3aecd08b | 2402 | SSA_NAME_VALUE (lhs) = rhs; |
6de9cd9a DN |
2403 | |
2404 | /* alloca never returns zero and the address of a non-weak symbol | |
2405 | is never zero. NOP_EXPRs and CONVERT_EXPRs can be completely | |
2406 | stripped as they do not affect this equivalence. */ | |
2407 | while (TREE_CODE (rhs) == NOP_EXPR | |
2408 | || TREE_CODE (rhs) == CONVERT_EXPR) | |
2409 | rhs = TREE_OPERAND (rhs, 0); | |
2410 | ||
2411 | if (alloca_call_p (rhs) | |
2412 | || (TREE_CODE (rhs) == ADDR_EXPR | |
2413 | && DECL_P (TREE_OPERAND (rhs, 0)) | |
2414 | && ! DECL_WEAK (TREE_OPERAND (rhs, 0)))) | |
fdabe5c2 | 2415 | record_var_is_nonzero (lhs); |
6de9cd9a DN |
2416 | |
2417 | /* IOR of any value with a nonzero value will result in a nonzero | |
2418 | value. Even if we do not know the exact result recording that | |
2419 | the result is nonzero is worth the effort. */ | |
2420 | if (TREE_CODE (rhs) == BIT_IOR_EXPR | |
2421 | && integer_nonzerop (TREE_OPERAND (rhs, 1))) | |
fdabe5c2 | 2422 | record_var_is_nonzero (lhs); |
6de9cd9a DN |
2423 | } |
2424 | ||
2425 | /* Look at both sides for pointer dereferences. If we find one, then | |
2426 | the pointer must be nonnull and we can enter that equivalence into | |
2427 | the hash tables. */ | |
dd747311 JL |
2428 | if (flag_delete_null_pointer_checks) |
2429 | for (i = 0; i < 2; i++) | |
2430 | { | |
2431 | tree t = TREE_OPERAND (stmt, i); | |
2432 | ||
2433 | /* Strip away any COMPONENT_REFs. */ | |
2434 | while (TREE_CODE (t) == COMPONENT_REF) | |
2435 | t = TREE_OPERAND (t, 0); | |
2436 | ||
2437 | /* Now see if this is a pointer dereference. */ | |
7ccf35ed DN |
2438 | if (TREE_CODE (t) == INDIRECT_REF |
2439 | || TREE_CODE (t) == ALIGN_INDIRECT_REF | |
2440 | || TREE_CODE (t) == MISALIGNED_INDIRECT_REF) | |
dd747311 JL |
2441 | { |
2442 | tree op = TREE_OPERAND (t, 0); | |
2443 | ||
2444 | /* If the pointer is a SSA variable, then enter new | |
2445 | equivalences into the hash table. */ | |
2446 | while (TREE_CODE (op) == SSA_NAME) | |
2447 | { | |
2448 | tree def = SSA_NAME_DEF_STMT (op); | |
2449 | ||
fdabe5c2 | 2450 | record_var_is_nonzero (op); |
dd747311 JL |
2451 | |
2452 | /* And walk up the USE-DEF chains noting other SSA_NAMEs | |
2453 | which are known to have a nonzero value. */ | |
2454 | if (def | |
2455 | && TREE_CODE (def) == MODIFY_EXPR | |
2456 | && TREE_CODE (TREE_OPERAND (def, 1)) == NOP_EXPR) | |
2457 | op = TREE_OPERAND (TREE_OPERAND (def, 1), 0); | |
2458 | else | |
2459 | break; | |
2460 | } | |
2461 | } | |
2462 | } | |
6de9cd9a DN |
2463 | |
2464 | /* A memory store, even an aliased store, creates a useful | |
2465 | equivalence. By exchanging the LHS and RHS, creating suitable | |
2466 | vops and recording the result in the available expression table, | |
2467 | we may be able to expose more redundant loads. */ | |
2468 | if (!ann->has_volatile_ops | |
2469 | && (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME | |
2470 | || is_gimple_min_invariant (TREE_OPERAND (stmt, 1))) | |
2471 | && !is_gimple_reg (lhs)) | |
2472 | { | |
2473 | tree rhs = TREE_OPERAND (stmt, 1); | |
2474 | tree new; | |
6de9cd9a DN |
2475 | |
2476 | /* FIXME: If the LHS of the assignment is a bitfield and the RHS | |
2477 | is a constant, we need to adjust the constant to fit into the | |
2478 | type of the LHS. If the LHS is a bitfield and the RHS is not | |
2479 | a constant, then we can not record any equivalences for this | |
2480 | statement since we would need to represent the widening or | |
2481 | narrowing of RHS. This fixes gcc.c-torture/execute/921016-1.c | |
2482 | and should not be necessary if GCC represented bitfields | |
2483 | properly. */ | |
2484 | if (lhs_code == COMPONENT_REF | |
2485 | && DECL_BIT_FIELD (TREE_OPERAND (lhs, 1))) | |
2486 | { | |
2487 | if (TREE_CONSTANT (rhs)) | |
2488 | rhs = widen_bitfield (rhs, TREE_OPERAND (lhs, 1), lhs); | |
2489 | else | |
2490 | rhs = NULL; | |
2491 | ||
2492 | /* If the value overflowed, then we can not use this equivalence. */ | |
2493 | if (rhs && ! is_gimple_min_invariant (rhs)) | |
2494 | rhs = NULL; | |
2495 | } | |
2496 | ||
2497 | if (rhs) | |
2498 | { | |
6de9cd9a DN |
2499 | /* Build a new statement with the RHS and LHS exchanged. */ |
2500 | new = build (MODIFY_EXPR, TREE_TYPE (stmt), rhs, lhs); | |
2501 | ||
1a24f92f | 2502 | create_ssa_artficial_load_stmt (&(ann->operands), new); |
6de9cd9a DN |
2503 | |
2504 | /* Finally enter the statement into the available expression | |
2505 | table. */ | |
48732f23 | 2506 | lookup_avail_expr (new, true); |
6de9cd9a DN |
2507 | } |
2508 | } | |
2509 | } | |
2510 | ||
ff2ad0f7 DN |
2511 | /* Replace *OP_P in STMT with any known equivalent value for *OP_P from |
2512 | CONST_AND_COPIES. */ | |
2513 | ||
2514 | static bool | |
6f2aec07 | 2515 | cprop_operand (tree stmt, use_operand_p op_p) |
ff2ad0f7 DN |
2516 | { |
2517 | bool may_have_exposed_new_symbols = false; | |
2518 | tree val; | |
2519 | tree op = USE_FROM_PTR (op_p); | |
2520 | ||
2521 | /* If the operand has a known constant value or it is known to be a | |
2522 | copy of some other variable, use the value or copy stored in | |
2523 | CONST_AND_COPIES. */ | |
3aecd08b JL |
2524 | val = SSA_NAME_VALUE (op); |
2525 | if (val && TREE_CODE (val) != VALUE_HANDLE) | |
ff2ad0f7 DN |
2526 | { |
2527 | tree op_type, val_type; | |
2528 | ||
2529 | /* Do not change the base variable in the virtual operand | |
2530 | tables. That would make it impossible to reconstruct | |
2531 | the renamed virtual operand if we later modify this | |
2532 | statement. Also only allow the new value to be an SSA_NAME | |
2533 | for propagation into virtual operands. */ | |
2534 | if (!is_gimple_reg (op) | |
2535 | && (get_virtual_var (val) != get_virtual_var (op) | |
2536 | || TREE_CODE (val) != SSA_NAME)) | |
2537 | return false; | |
2538 | ||
2539 | /* Get the toplevel type of each operand. */ | |
2540 | op_type = TREE_TYPE (op); | |
2541 | val_type = TREE_TYPE (val); | |
2542 | ||
2543 | /* While both types are pointers, get the type of the object | |
2544 | pointed to. */ | |
2545 | while (POINTER_TYPE_P (op_type) && POINTER_TYPE_P (val_type)) | |
2546 | { | |
2547 | op_type = TREE_TYPE (op_type); | |
2548 | val_type = TREE_TYPE (val_type); | |
2549 | } | |
2550 | ||
63b88252 RH |
2551 | /* Make sure underlying types match before propagating a constant by |
2552 | converting the constant to the proper type. Note that convert may | |
2553 | return a non-gimple expression, in which case we ignore this | |
2554 | propagation opportunity. */ | |
2555 | if (TREE_CODE (val) != SSA_NAME) | |
ff2ad0f7 | 2556 | { |
63b88252 RH |
2557 | if (!lang_hooks.types_compatible_p (op_type, val_type)) |
2558 | { | |
2559 | val = fold_convert (TREE_TYPE (op), val); | |
2560 | if (!is_gimple_min_invariant (val)) | |
2561 | return false; | |
2562 | } | |
ff2ad0f7 DN |
2563 | } |
2564 | ||
2565 | /* Certain operands are not allowed to be copy propagated due | |
2566 | to their interaction with exception handling and some GCC | |
2567 | extensions. */ | |
63b88252 | 2568 | else if (!may_propagate_copy (op, val)) |
ff2ad0f7 DN |
2569 | return false; |
2570 | ||
2571 | /* Dump details. */ | |
2572 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2573 | { | |
2574 | fprintf (dump_file, " Replaced '"); | |
2575 | print_generic_expr (dump_file, op, dump_flags); | |
2576 | fprintf (dump_file, "' with %s '", | |
2577 | (TREE_CODE (val) != SSA_NAME ? "constant" : "variable")); | |
2578 | print_generic_expr (dump_file, val, dump_flags); | |
2579 | fprintf (dump_file, "'\n"); | |
2580 | } | |
2581 | ||
2582 | /* If VAL is an ADDR_EXPR or a constant of pointer type, note | |
2583 | that we may have exposed a new symbol for SSA renaming. */ | |
2584 | if (TREE_CODE (val) == ADDR_EXPR | |
2585 | || (POINTER_TYPE_P (TREE_TYPE (op)) | |
2586 | && is_gimple_min_invariant (val))) | |
2587 | may_have_exposed_new_symbols = true; | |
2588 | ||
2589 | propagate_value (op_p, val); | |
2590 | ||
2591 | /* And note that we modified this statement. This is now | |
2592 | safe, even if we changed virtual operands since we will | |
2593 | rescan the statement and rewrite its operands again. */ | |
68b9f53b | 2594 | modify_stmt (stmt); |
ff2ad0f7 DN |
2595 | } |
2596 | return may_have_exposed_new_symbols; | |
2597 | } | |
2598 | ||
2599 | /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current | |
2600 | known value for that SSA_NAME (or NULL if no value is known). | |
2601 | ||
2602 | Propagate values from CONST_AND_COPIES into the uses, vuses and | |
2603 | v_may_def_ops of STMT. */ | |
2604 | ||
2605 | static bool | |
6f2aec07 | 2606 | cprop_into_stmt (tree stmt) |
ff2ad0f7 DN |
2607 | { |
2608 | bool may_have_exposed_new_symbols = false; | |
4c124b4c AM |
2609 | use_operand_p op_p; |
2610 | ssa_op_iter iter; | |
c7f90219 | 2611 | tree rhs; |
ff2ad0f7 | 2612 | |
4c124b4c | 2613 | FOR_EACH_SSA_USE_OPERAND (op_p, stmt, iter, SSA_OP_ALL_USES) |
ff2ad0f7 | 2614 | { |
ff2ad0f7 | 2615 | if (TREE_CODE (USE_FROM_PTR (op_p)) == SSA_NAME) |
6f2aec07 | 2616 | may_have_exposed_new_symbols |= cprop_operand (stmt, op_p); |
ff2ad0f7 DN |
2617 | } |
2618 | ||
c7f90219 SB |
2619 | if (may_have_exposed_new_symbols) |
2620 | { | |
2621 | rhs = get_rhs (stmt); | |
2622 | if (rhs && TREE_CODE (rhs) == ADDR_EXPR) | |
2623 | recompute_tree_invarant_for_addr_expr (rhs); | |
2624 | } | |
2625 | ||
ff2ad0f7 DN |
2626 | return may_have_exposed_new_symbols; |
2627 | } | |
2628 | ||
2629 | ||
6de9cd9a DN |
2630 | /* Optimize the statement pointed by iterator SI. |
2631 | ||
2632 | We try to perform some simplistic global redundancy elimination and | |
2633 | constant propagation: | |
2634 | ||
2635 | 1- To detect global redundancy, we keep track of expressions that have | |
2636 | been computed in this block and its dominators. If we find that the | |
2637 | same expression is computed more than once, we eliminate repeated | |
2638 | computations by using the target of the first one. | |
2639 | ||
2640 | 2- Constant values and copy assignments. This is used to do very | |
2641 | simplistic constant and copy propagation. When a constant or copy | |
2642 | assignment is found, we map the value on the RHS of the assignment to | |
2643 | the variable in the LHS in the CONST_AND_COPIES table. */ | |
2644 | ||
2645 | static void | |
1eaba2f2 | 2646 | optimize_stmt (struct dom_walk_data *walk_data, basic_block bb, |
6de9cd9a DN |
2647 | block_stmt_iterator si) |
2648 | { | |
2649 | stmt_ann_t ann; | |
2650 | tree stmt; | |
6de9cd9a DN |
2651 | bool may_optimize_p; |
2652 | bool may_have_exposed_new_symbols = false; | |
6de9cd9a DN |
2653 | |
2654 | stmt = bsi_stmt (si); | |
2655 | ||
2656 | get_stmt_operands (stmt); | |
2657 | ann = stmt_ann (stmt); | |
6de9cd9a DN |
2658 | opt_stats.num_stmts++; |
2659 | may_have_exposed_new_symbols = false; | |
2660 | ||
2661 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2662 | { | |
2663 | fprintf (dump_file, "Optimizing statement "); | |
2664 | print_generic_stmt (dump_file, stmt, TDF_SLIM); | |
2665 | } | |
2666 | ||
a32b97a2 | 2667 | /* Const/copy propagate into USES, VUSES and the RHS of V_MAY_DEFs. */ |
6f2aec07 | 2668 | may_have_exposed_new_symbols = cprop_into_stmt (stmt); |
6de9cd9a DN |
2669 | |
2670 | /* If the statement has been modified with constant replacements, | |
2671 | fold its RHS before checking for redundant computations. */ | |
2672 | if (ann->modified) | |
2673 | { | |
2674 | /* Try to fold the statement making sure that STMT is kept | |
2675 | up to date. */ | |
2676 | if (fold_stmt (bsi_stmt_ptr (si))) | |
2677 | { | |
2678 | stmt = bsi_stmt (si); | |
2679 | ann = stmt_ann (stmt); | |
2680 | ||
2681 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2682 | { | |
2683 | fprintf (dump_file, " Folded to: "); | |
2684 | print_generic_stmt (dump_file, stmt, TDF_SLIM); | |
2685 | } | |
2686 | } | |
2687 | ||
2688 | /* Constant/copy propagation above may change the set of | |
2689 | virtual operands associated with this statement. Folding | |
2690 | may remove the need for some virtual operands. | |
2691 | ||
2692 | Indicate we will need to rescan and rewrite the statement. */ | |
2693 | may_have_exposed_new_symbols = true; | |
2694 | } | |
2695 | ||
2696 | /* Check for redundant computations. Do this optimization only | |
2697 | for assignments that have no volatile ops and conditionals. */ | |
2698 | may_optimize_p = (!ann->has_volatile_ops | |
2699 | && ((TREE_CODE (stmt) == RETURN_EXPR | |
2700 | && TREE_OPERAND (stmt, 0) | |
2701 | && TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR | |
2702 | && ! (TREE_SIDE_EFFECTS | |
2703 | (TREE_OPERAND (TREE_OPERAND (stmt, 0), 1)))) | |
2704 | || (TREE_CODE (stmt) == MODIFY_EXPR | |
2705 | && ! TREE_SIDE_EFFECTS (TREE_OPERAND (stmt, 1))) | |
2706 | || TREE_CODE (stmt) == COND_EXPR | |
2707 | || TREE_CODE (stmt) == SWITCH_EXPR)); | |
2708 | ||
2709 | if (may_optimize_p) | |
2710 | may_have_exposed_new_symbols | |
2711 | |= eliminate_redundant_computations (walk_data, stmt, ann); | |
2712 | ||
2713 | /* Record any additional equivalences created by this statement. */ | |
2714 | if (TREE_CODE (stmt) == MODIFY_EXPR) | |
2715 | record_equivalences_from_stmt (stmt, | |
6de9cd9a DN |
2716 | may_optimize_p, |
2717 | ann); | |
2718 | ||
9fae925b | 2719 | register_definitions_for_stmt (stmt); |
6de9cd9a DN |
2720 | |
2721 | /* If STMT is a COND_EXPR and it was modified, then we may know | |
2722 | where it goes. If that is the case, then mark the CFG as altered. | |
2723 | ||
2724 | This will cause us to later call remove_unreachable_blocks and | |
2725 | cleanup_tree_cfg when it is safe to do so. It is not safe to | |
2726 | clean things up here since removal of edges and such can trigger | |
2727 | the removal of PHI nodes, which in turn can release SSA_NAMEs to | |
2728 | the manager. | |
2729 | ||
2730 | That's all fine and good, except that once SSA_NAMEs are released | |
2731 | to the manager, we must not call create_ssa_name until all references | |
2732 | to released SSA_NAMEs have been eliminated. | |
2733 | ||
2734 | All references to the deleted SSA_NAMEs can not be eliminated until | |
2735 | we remove unreachable blocks. | |
2736 | ||
2737 | We can not remove unreachable blocks until after we have completed | |
2738 | any queued jump threading. | |
2739 | ||
2740 | We can not complete any queued jump threads until we have taken | |
2741 | appropriate variables out of SSA form. Taking variables out of | |
2742 | SSA form can call create_ssa_name and thus we lose. | |
2743 | ||
2744 | Ultimately I suspect we're going to need to change the interface | |
2745 | into the SSA_NAME manager. */ | |
2746 | ||
2747 | if (ann->modified) | |
2748 | { | |
2749 | tree val = NULL; | |
2750 | ||
2751 | if (TREE_CODE (stmt) == COND_EXPR) | |
2752 | val = COND_EXPR_COND (stmt); | |
2753 | else if (TREE_CODE (stmt) == SWITCH_EXPR) | |
2754 | val = SWITCH_COND (stmt); | |
2755 | ||
1eaba2f2 | 2756 | if (val && TREE_CODE (val) == INTEGER_CST && find_taken_edge (bb, val)) |
6de9cd9a | 2757 | cfg_altered = true; |
1eaba2f2 RH |
2758 | |
2759 | /* If we simplified a statement in such a way as to be shown that it | |
2760 | cannot trap, update the eh information and the cfg to match. */ | |
2761 | if (maybe_clean_eh_stmt (stmt)) | |
2762 | { | |
2763 | bitmap_set_bit (need_eh_cleanup, bb->index); | |
2764 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2765 | fprintf (dump_file, " Flagged to clear EH edges.\n"); | |
2766 | } | |
6de9cd9a | 2767 | } |
1eaba2f2 | 2768 | |
6de9cd9a | 2769 | if (may_have_exposed_new_symbols) |
a6e1aa26 | 2770 | VARRAY_PUSH_TREE (stmts_to_rescan, bsi_stmt (si)); |
6de9cd9a DN |
2771 | } |
2772 | ||
2773 | /* Replace the RHS of STMT with NEW_RHS. If RHS can be found in the | |
2774 | available expression hashtable, then return the LHS from the hash | |
2775 | table. | |
2776 | ||
2777 | If INSERT is true, then we also update the available expression | |
2778 | hash table to account for the changes made to STMT. */ | |
2779 | ||
2780 | static tree | |
48732f23 | 2781 | update_rhs_and_lookup_avail_expr (tree stmt, tree new_rhs, bool insert) |
6de9cd9a DN |
2782 | { |
2783 | tree cached_lhs = NULL; | |
2784 | ||
2785 | /* Remove the old entry from the hash table. */ | |
2786 | if (insert) | |
2787 | { | |
2788 | struct expr_hash_elt element; | |
2789 | ||
2790 | initialize_hash_element (stmt, NULL, &element); | |
2791 | htab_remove_elt_with_hash (avail_exprs, &element, element.hash); | |
2792 | } | |
2793 | ||
2794 | /* Now update the RHS of the assignment. */ | |
2795 | TREE_OPERAND (stmt, 1) = new_rhs; | |
2796 | ||
2797 | /* Now lookup the updated statement in the hash table. */ | |
48732f23 | 2798 | cached_lhs = lookup_avail_expr (stmt, insert); |
6de9cd9a DN |
2799 | |
2800 | /* We have now called lookup_avail_expr twice with two different | |
2801 | versions of this same statement, once in optimize_stmt, once here. | |
2802 | ||
2803 | We know the call in optimize_stmt did not find an existing entry | |
2804 | in the hash table, so a new entry was created. At the same time | |
2805 | this statement was pushed onto the BLOCK_AVAIL_EXPRS varray. | |
2806 | ||
2807 | If this call failed to find an existing entry on the hash table, | |
2808 | then the new version of this statement was entered into the | |
2809 | hash table. And this statement was pushed onto BLOCK_AVAIL_EXPR | |
2810 | for the second time. So there are two copies on BLOCK_AVAIL_EXPRs | |
2811 | ||
2812 | If this call succeeded, we still have one copy of this statement | |
2813 | on the BLOCK_AVAIL_EXPRs varray. | |
2814 | ||
2815 | For both cases, we need to pop the most recent entry off the | |
2816 | BLOCK_AVAIL_EXPRs varray. For the case where we never found this | |
2817 | statement in the hash tables, that will leave precisely one | |
2818 | copy of this statement on BLOCK_AVAIL_EXPRs. For the case where | |
2819 | we found a copy of this statement in the second hash table lookup | |
2820 | we want _no_ copies of this statement in BLOCK_AVAIL_EXPRs. */ | |
2821 | if (insert) | |
48732f23 | 2822 | VARRAY_POP (avail_exprs_stack); |
6de9cd9a DN |
2823 | |
2824 | /* And make sure we record the fact that we modified this | |
2825 | statement. */ | |
68b9f53b | 2826 | modify_stmt (stmt); |
6de9cd9a DN |
2827 | |
2828 | return cached_lhs; | |
2829 | } | |
2830 | ||
2831 | /* Search for an existing instance of STMT in the AVAIL_EXPRS table. If | |
2832 | found, return its LHS. Otherwise insert STMT in the table and return | |
2833 | NULL_TREE. | |
2834 | ||
2835 | Also, when an expression is first inserted in the AVAIL_EXPRS table, it | |
2836 | is also added to the stack pointed by BLOCK_AVAIL_EXPRS_P, so that they | |
2837 | can be removed when we finish processing this block and its children. | |
2838 | ||
2839 | NOTE: This function assumes that STMT is a MODIFY_EXPR node that | |
2840 | contains no CALL_EXPR on its RHS and makes no volatile nor | |
2841 | aliased references. */ | |
2842 | ||
2843 | static tree | |
48732f23 | 2844 | lookup_avail_expr (tree stmt, bool insert) |
6de9cd9a DN |
2845 | { |
2846 | void **slot; | |
2847 | tree lhs; | |
2848 | tree temp; | |
2849 | struct expr_hash_elt *element = xcalloc (sizeof (struct expr_hash_elt), 1); | |
2850 | ||
2851 | lhs = TREE_CODE (stmt) == MODIFY_EXPR ? TREE_OPERAND (stmt, 0) : NULL; | |
2852 | ||
2853 | initialize_hash_element (stmt, lhs, element); | |
2854 | ||
2855 | /* Don't bother remembering constant assignments and copy operations. | |
2856 | Constants and copy operations are handled by the constant/copy propagator | |
2857 | in optimize_stmt. */ | |
2858 | if (TREE_CODE (element->rhs) == SSA_NAME | |
2859 | || is_gimple_min_invariant (element->rhs)) | |
2860 | { | |
2861 | free (element); | |
2862 | return NULL_TREE; | |
2863 | } | |
2864 | ||
2865 | /* If this is an equality test against zero, see if we have recorded a | |
2866 | nonzero value for the variable in question. */ | |
2867 | if ((TREE_CODE (element->rhs) == EQ_EXPR | |
2868 | || TREE_CODE (element->rhs) == NE_EXPR) | |
2869 | && TREE_CODE (TREE_OPERAND (element->rhs, 0)) == SSA_NAME | |
2870 | && integer_zerop (TREE_OPERAND (element->rhs, 1))) | |
2871 | { | |
2872 | int indx = SSA_NAME_VERSION (TREE_OPERAND (element->rhs, 0)); | |
2873 | ||
2874 | if (bitmap_bit_p (nonzero_vars, indx)) | |
2875 | { | |
2876 | tree t = element->rhs; | |
2877 | free (element); | |
2878 | ||
2879 | if (TREE_CODE (t) == EQ_EXPR) | |
2880 | return boolean_false_node; | |
2881 | else | |
2882 | return boolean_true_node; | |
2883 | } | |
2884 | } | |
2885 | ||
2886 | /* Finally try to find the expression in the main expression hash table. */ | |
2887 | slot = htab_find_slot_with_hash (avail_exprs, element, element->hash, | |
2888 | (insert ? INSERT : NO_INSERT)); | |
2889 | if (slot == NULL) | |
2890 | { | |
2891 | free (element); | |
2892 | return NULL_TREE; | |
2893 | } | |
2894 | ||
2895 | if (*slot == NULL) | |
2896 | { | |
2897 | *slot = (void *) element; | |
48732f23 | 2898 | VARRAY_PUSH_TREE (avail_exprs_stack, stmt ? stmt : element->rhs); |
6de9cd9a DN |
2899 | return NULL_TREE; |
2900 | } | |
2901 | ||
2902 | /* Extract the LHS of the assignment so that it can be used as the current | |
2903 | definition of another variable. */ | |
2904 | lhs = ((struct expr_hash_elt *)*slot)->lhs; | |
2905 | ||
2906 | /* See if the LHS appears in the CONST_AND_COPIES table. If it does, then | |
2907 | use the value from the const_and_copies table. */ | |
2908 | if (TREE_CODE (lhs) == SSA_NAME) | |
2909 | { | |
3aecd08b JL |
2910 | temp = SSA_NAME_VALUE (lhs); |
2911 | if (temp && TREE_CODE (temp) != VALUE_HANDLE) | |
6de9cd9a DN |
2912 | lhs = temp; |
2913 | } | |
2914 | ||
2915 | free (element); | |
2916 | return lhs; | |
2917 | } | |
2918 | ||
2919 | /* Given a condition COND, record into HI_P, LO_P and INVERTED_P the | |
2920 | range of values that result in the conditional having a true value. | |
2921 | ||
2922 | Return true if we are successful in extracting a range from COND and | |
2923 | false if we are unsuccessful. */ | |
2924 | ||
2925 | static bool | |
2926 | extract_range_from_cond (tree cond, tree *hi_p, tree *lo_p, int *inverted_p) | |
2927 | { | |
2928 | tree op1 = TREE_OPERAND (cond, 1); | |
2929 | tree high, low, type; | |
2930 | int inverted; | |
2931 | ||
2932 | /* Experiments have shown that it's rarely, if ever useful to | |
2933 | record ranges for enumerations. Presumably this is due to | |
2934 | the fact that they're rarely used directly. They are typically | |
2935 | cast into an integer type and used that way. */ | |
2936 | if (TREE_CODE (TREE_TYPE (op1)) != INTEGER_TYPE) | |
2937 | return 0; | |
2938 | ||
2939 | type = TREE_TYPE (op1); | |
2940 | ||
2941 | switch (TREE_CODE (cond)) | |
2942 | { | |
2943 | case EQ_EXPR: | |
2944 | high = low = op1; | |
2945 | inverted = 0; | |
2946 | break; | |
2947 | ||
2948 | case NE_EXPR: | |
2949 | high = low = op1; | |
2950 | inverted = 1; | |
2951 | break; | |
2952 | ||
2953 | case GE_EXPR: | |
2954 | low = op1; | |
2955 | high = TYPE_MAX_VALUE (type); | |
2956 | inverted = 0; | |
2957 | break; | |
2958 | ||
2959 | case GT_EXPR: | |
2960 | low = int_const_binop (PLUS_EXPR, op1, integer_one_node, 1); | |
2961 | high = TYPE_MAX_VALUE (type); | |
2962 | inverted = 0; | |
2963 | break; | |
2964 | ||
2965 | case LE_EXPR: | |
2966 | high = op1; | |
2967 | low = TYPE_MIN_VALUE (type); | |
2968 | inverted = 0; | |
2969 | break; | |
2970 | ||
2971 | case LT_EXPR: | |
2972 | high = int_const_binop (MINUS_EXPR, op1, integer_one_node, 1); | |
2973 | low = TYPE_MIN_VALUE (type); | |
2974 | inverted = 0; | |
2975 | break; | |
2976 | ||
2977 | default: | |
2978 | return 0; | |
2979 | } | |
2980 | ||
2981 | *hi_p = high; | |
2982 | *lo_p = low; | |
2983 | *inverted_p = inverted; | |
2984 | return 1; | |
2985 | } | |
2986 | ||
2987 | /* Record a range created by COND for basic block BB. */ | |
2988 | ||
2989 | static void | |
fdabe5c2 | 2990 | record_range (tree cond, basic_block bb) |
6de9cd9a DN |
2991 | { |
2992 | /* We explicitly ignore NE_EXPRs. They rarely allow for meaningful | |
2993 | range optimizations and significantly complicate the implementation. */ | |
6615c446 | 2994 | if (COMPARISON_CLASS_P (cond) |
6de9cd9a DN |
2995 | && TREE_CODE (cond) != NE_EXPR |
2996 | && TREE_CODE (TREE_TYPE (TREE_OPERAND (cond, 1))) == INTEGER_TYPE) | |
2997 | { | |
23530866 JL |
2998 | struct vrp_hash_elt *vrp_hash_elt; |
2999 | struct vrp_element *element; | |
3000 | varray_type *vrp_records_p; | |
3001 | void **slot; | |
3002 | ||
6de9cd9a | 3003 | |
23530866 JL |
3004 | vrp_hash_elt = xmalloc (sizeof (struct vrp_hash_elt)); |
3005 | vrp_hash_elt->var = TREE_OPERAND (cond, 0); | |
3006 | vrp_hash_elt->records = NULL; | |
3007 | slot = htab_find_slot (vrp_data, vrp_hash_elt, INSERT); | |
6de9cd9a | 3008 | |
23530866 | 3009 | if (*slot == NULL) |
4a198dea | 3010 | *slot = (void *) vrp_hash_elt; |
23530866 | 3011 | |
4a198dea | 3012 | vrp_hash_elt = (struct vrp_hash_elt *) *slot; |
23530866 JL |
3013 | vrp_records_p = &vrp_hash_elt->records; |
3014 | ||
3015 | element = ggc_alloc (sizeof (struct vrp_element)); | |
6de9cd9a DN |
3016 | element->low = NULL; |
3017 | element->high = NULL; | |
3018 | element->cond = cond; | |
3019 | element->bb = bb; | |
3020 | ||
3021 | if (*vrp_records_p == NULL) | |
23530866 | 3022 | VARRAY_GENERIC_PTR_INIT (*vrp_records_p, 2, "vrp records"); |
6de9cd9a DN |
3023 | |
3024 | VARRAY_PUSH_GENERIC_PTR (*vrp_records_p, element); | |
fdabe5c2 | 3025 | VARRAY_PUSH_TREE (vrp_variables_stack, TREE_OPERAND (cond, 0)); |
6de9cd9a DN |
3026 | } |
3027 | } | |
3028 | ||
3029 | /* Given a conditional statement IF_STMT, return the assignment 'X = Y' | |
3030 | known to be true depending on which arm of IF_STMT is taken. | |
3031 | ||
3032 | Not all conditional statements will result in a useful assignment. | |
3033 | Return NULL_TREE in that case. | |
3034 | ||
3035 | Also enter into the available expression table statements of | |
3036 | the form: | |
3037 | ||
3038 | TRUE ARM FALSE ARM | |
3039 | 1 = cond 1 = cond' | |
3040 | 0 = cond' 0 = cond | |
3041 | ||
3042 | This allows us to lookup the condition in a dominated block and | |
3043 | get back a constant indicating if the condition is true. */ | |
3044 | ||
3045 | static struct eq_expr_value | |
3046 | get_eq_expr_value (tree if_stmt, | |
3047 | int true_arm, | |
fdabe5c2 | 3048 | basic_block bb) |
6de9cd9a DN |
3049 | { |
3050 | tree cond; | |
3051 | struct eq_expr_value retval; | |
3052 | ||
3053 | cond = COND_EXPR_COND (if_stmt); | |
3054 | retval.src = NULL; | |
3055 | retval.dst = NULL; | |
3056 | ||
3057 | /* If the conditional is a single variable 'X', return 'X = 1' for | |
3058 | the true arm and 'X = 0' on the false arm. */ | |
3059 | if (TREE_CODE (cond) == SSA_NAME) | |
3060 | { | |
3061 | retval.dst = cond; | |
e9ea8bd5 | 3062 | retval.src = constant_boolean_node (true_arm, TREE_TYPE (cond)); |
6de9cd9a DN |
3063 | return retval; |
3064 | } | |
3065 | ||
3066 | /* If we have a comparison expression, then record its result into | |
3067 | the available expression table. */ | |
6615c446 | 3068 | if (COMPARISON_CLASS_P (cond)) |
6de9cd9a DN |
3069 | { |
3070 | tree op0 = TREE_OPERAND (cond, 0); | |
3071 | tree op1 = TREE_OPERAND (cond, 1); | |
3072 | ||
3073 | /* Special case comparing booleans against a constant as we know | |
454ff5cb | 3074 | the value of OP0 on both arms of the branch. i.e., we can record |
6de9cd9a DN |
3075 | an equivalence for OP0 rather than COND. */ |
3076 | if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR) | |
3077 | && TREE_CODE (op0) == SSA_NAME | |
3078 | && TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE | |
3079 | && is_gimple_min_invariant (op1)) | |
3080 | { | |
3081 | if ((TREE_CODE (cond) == EQ_EXPR && true_arm) | |
3082 | || (TREE_CODE (cond) == NE_EXPR && ! true_arm)) | |
3083 | { | |
3084 | retval.src = op1; | |
3085 | } | |
3086 | else | |
3087 | { | |
3088 | if (integer_zerop (op1)) | |
3089 | retval.src = boolean_true_node; | |
3090 | else | |
3091 | retval.src = boolean_false_node; | |
3092 | } | |
3093 | retval.dst = op0; | |
3094 | return retval; | |
3095 | } | |
3096 | ||
3097 | if (TREE_CODE (op0) == SSA_NAME | |
3098 | && (is_gimple_min_invariant (op1) || TREE_CODE (op1) == SSA_NAME)) | |
3099 | { | |
3100 | tree inverted = invert_truthvalue (cond); | |
3101 | ||
3102 | /* When we find an available expression in the hash table, we replace | |
3103 | the expression with the LHS of the statement in the hash table. | |
3104 | ||
3105 | So, we want to build statements such as "1 = <condition>" on the | |
3106 | true arm and "0 = <condition>" on the false arm. That way if we | |
3107 | find the expression in the table, we will replace it with its | |
3108 | known constant value. Also insert inversions of the result and | |
3109 | condition into the hash table. */ | |
3110 | if (true_arm) | |
3111 | { | |
48732f23 JL |
3112 | record_cond (cond, boolean_true_node); |
3113 | record_dominating_conditions (cond); | |
3114 | record_cond (inverted, boolean_false_node); | |
6de9cd9a DN |
3115 | |
3116 | if (TREE_CONSTANT (op1)) | |
fdabe5c2 | 3117 | record_range (cond, bb); |
6de9cd9a DN |
3118 | |
3119 | /* If the conditional is of the form 'X == Y', return 'X = Y' | |
3120 | for the true arm. */ | |
3121 | if (TREE_CODE (cond) == EQ_EXPR) | |
3122 | { | |
3123 | retval.dst = op0; | |
3124 | retval.src = op1; | |
3125 | return retval; | |
3126 | } | |
3127 | } | |
3128 | else | |
3129 | { | |
3130 | ||
48732f23 JL |
3131 | record_cond (inverted, boolean_true_node); |
3132 | record_dominating_conditions (inverted); | |
3133 | record_cond (cond, boolean_false_node); | |
6de9cd9a DN |
3134 | |
3135 | if (TREE_CONSTANT (op1)) | |
fdabe5c2 | 3136 | record_range (inverted, bb); |
6de9cd9a DN |
3137 | |
3138 | /* If the conditional is of the form 'X != Y', return 'X = Y' | |
3139 | for the false arm. */ | |
3140 | if (TREE_CODE (cond) == NE_EXPR) | |
3141 | { | |
3142 | retval.dst = op0; | |
3143 | retval.src = op1; | |
3144 | return retval; | |
3145 | } | |
3146 | } | |
3147 | } | |
3148 | } | |
3149 | ||
3150 | return retval; | |
3151 | } | |
3152 | ||
23530866 JL |
3153 | /* Hashing and equality functions for VRP_DATA. |
3154 | ||
3155 | Since this hash table is addressed by SSA_NAMEs, we can hash on | |
3156 | their version number and equality can be determined with a | |
3157 | pointer comparison. */ | |
3158 | ||
3159 | static hashval_t | |
3160 | vrp_hash (const void *p) | |
3161 | { | |
3162 | tree var = ((struct vrp_hash_elt *)p)->var; | |
3163 | ||
3164 | return SSA_NAME_VERSION (var); | |
3165 | } | |
3166 | ||
3167 | static int | |
3168 | vrp_eq (const void *p1, const void *p2) | |
3169 | { | |
3170 | tree var1 = ((struct vrp_hash_elt *)p1)->var; | |
3171 | tree var2 = ((struct vrp_hash_elt *)p2)->var; | |
3172 | ||
3173 | return var1 == var2; | |
3174 | } | |
3175 | ||
6de9cd9a DN |
3176 | /* Hashing and equality functions for AVAIL_EXPRS. The table stores |
3177 | MODIFY_EXPR statements. We compute a value number for expressions using | |
3178 | the code of the expression and the SSA numbers of its operands. */ | |
3179 | ||
3180 | static hashval_t | |
3181 | avail_expr_hash (const void *p) | |
3182 | { | |
3183 | stmt_ann_t ann = ((struct expr_hash_elt *)p)->ann; | |
3184 | tree rhs = ((struct expr_hash_elt *)p)->rhs; | |
3185 | hashval_t val = 0; | |
3186 | size_t i; | |
3187 | vuse_optype vuses; | |
3188 | ||
3189 | /* iterative_hash_expr knows how to deal with any expression and | |
3190 | deals with commutative operators as well, so just use it instead | |
3191 | of duplicating such complexities here. */ | |
3192 | val = iterative_hash_expr (rhs, val); | |
3193 | ||
3194 | /* If the hash table entry is not associated with a statement, then we | |
3195 | can just hash the expression and not worry about virtual operands | |
3196 | and such. */ | |
3197 | if (!ann) | |
3198 | return val; | |
3199 | ||
3200 | /* Add the SSA version numbers of every vuse operand. This is important | |
3201 | because compound variables like arrays are not renamed in the | |
3202 | operands. Rather, the rename is done on the virtual variable | |
3203 | representing all the elements of the array. */ | |
3204 | vuses = VUSE_OPS (ann); | |
3205 | for (i = 0; i < NUM_VUSES (vuses); i++) | |
3206 | val = iterative_hash_expr (VUSE_OP (vuses, i), val); | |
3207 | ||
3208 | return val; | |
3209 | } | |
3210 | ||
940db2c8 RH |
3211 | static hashval_t |
3212 | real_avail_expr_hash (const void *p) | |
3213 | { | |
3214 | return ((const struct expr_hash_elt *)p)->hash; | |
3215 | } | |
6de9cd9a DN |
3216 | |
3217 | static int | |
3218 | avail_expr_eq (const void *p1, const void *p2) | |
3219 | { | |
3220 | stmt_ann_t ann1 = ((struct expr_hash_elt *)p1)->ann; | |
3221 | tree rhs1 = ((struct expr_hash_elt *)p1)->rhs; | |
3222 | stmt_ann_t ann2 = ((struct expr_hash_elt *)p2)->ann; | |
3223 | tree rhs2 = ((struct expr_hash_elt *)p2)->rhs; | |
3224 | ||
3225 | /* If they are the same physical expression, return true. */ | |
3226 | if (rhs1 == rhs2 && ann1 == ann2) | |
3227 | return true; | |
3228 | ||
3229 | /* If their codes are not equal, then quit now. */ | |
3230 | if (TREE_CODE (rhs1) != TREE_CODE (rhs2)) | |
3231 | return false; | |
3232 | ||
3233 | /* In case of a collision, both RHS have to be identical and have the | |
3234 | same VUSE operands. */ | |
3235 | if ((TREE_TYPE (rhs1) == TREE_TYPE (rhs2) | |
3236 | || lang_hooks.types_compatible_p (TREE_TYPE (rhs1), TREE_TYPE (rhs2))) | |
3237 | && operand_equal_p (rhs1, rhs2, OEP_PURE_SAME)) | |
3238 | { | |
3239 | vuse_optype ops1 = NULL; | |
3240 | vuse_optype ops2 = NULL; | |
3241 | size_t num_ops1 = 0; | |
3242 | size_t num_ops2 = 0; | |
3243 | size_t i; | |
3244 | ||
3245 | if (ann1) | |
3246 | { | |
3247 | ops1 = VUSE_OPS (ann1); | |
3248 | num_ops1 = NUM_VUSES (ops1); | |
3249 | } | |
3250 | ||
3251 | if (ann2) | |
3252 | { | |
3253 | ops2 = VUSE_OPS (ann2); | |
3254 | num_ops2 = NUM_VUSES (ops2); | |
3255 | } | |
3256 | ||
3257 | /* If the number of virtual uses is different, then we consider | |
3258 | them not equal. */ | |
3259 | if (num_ops1 != num_ops2) | |
3260 | return false; | |
3261 | ||
3262 | for (i = 0; i < num_ops1; i++) | |
3263 | if (VUSE_OP (ops1, i) != VUSE_OP (ops2, i)) | |
3264 | return false; | |
3265 | ||
1e128c5f GB |
3266 | gcc_assert (((struct expr_hash_elt *)p1)->hash |
3267 | == ((struct expr_hash_elt *)p2)->hash); | |
6de9cd9a DN |
3268 | return true; |
3269 | } | |
3270 | ||
3271 | return false; | |
3272 | } | |
3273 | ||
61ada8ae | 3274 | /* Given STMT and a pointer to the block local definitions BLOCK_DEFS_P, |
6de9cd9a DN |
3275 | register register all objects set by this statement into BLOCK_DEFS_P |
3276 | and CURRDEFS. */ | |
3277 | ||
3278 | static void | |
9fae925b | 3279 | register_definitions_for_stmt (tree stmt) |
6de9cd9a | 3280 | { |
4c124b4c AM |
3281 | tree def; |
3282 | ssa_op_iter iter; | |
6de9cd9a | 3283 | |
4c124b4c | 3284 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) |
6de9cd9a | 3285 | { |
6de9cd9a DN |
3286 | |
3287 | /* FIXME: We shouldn't be registering new defs if the variable | |
3288 | doesn't need to be renamed. */ | |
9fae925b | 3289 | register_new_def (def, &block_defs_stack); |
6de9cd9a | 3290 | } |
6de9cd9a DN |
3291 | } |
3292 |