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06598532 | 1 | /* High-level loop manipulation functions. |
711789cc | 2 | Copyright (C) 2004-2013 Free Software Foundation, Inc. |
48e1416a | 3 | |
06598532 | 4 | This file is part of GCC. |
48e1416a | 5 | |
06598532 | 6 | GCC is free software; you can redistribute it and/or modify it |
7 | under the terms of the GNU General Public License as published by the | |
8c4c00c1 | 8 | Free Software Foundation; either version 3, or (at your option) any |
06598532 | 9 | later version. |
48e1416a | 10 | |
06598532 | 11 | GCC is distributed in the hope that it will be useful, but WITHOUT |
12 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
48e1416a | 15 | |
06598532 | 16 | You should have received a copy of the GNU General Public License |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
06598532 | 19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
24 | #include "tree.h" | |
06598532 | 25 | #include "tm_p.h" |
06598532 | 26 | #include "basic-block.h" |
bc61cadb | 27 | #include "tree-ssa-alias.h" |
28 | #include "internal-fn.h" | |
29 | #include "gimple-expr.h" | |
30 | #include "is-a.h" | |
e795d6e1 | 31 | #include "gimple.h" |
a8783bee | 32 | #include "gimplify.h" |
dcf1a1ec | 33 | #include "gimple-iterator.h" |
e795d6e1 | 34 | #include "gimplify-me.h" |
073c1fd5 | 35 | #include "gimple-ssa.h" |
36 | #include "tree-cfg.h" | |
37 | #include "tree-phinodes.h" | |
38 | #include "ssa-iterators.h" | |
9ed99284 | 39 | #include "stringpool.h" |
073c1fd5 | 40 | #include "tree-ssanames.h" |
05d9c18a | 41 | #include "tree-ssa-loop-ivopts.h" |
42 | #include "tree-ssa-loop-manip.h" | |
43 | #include "tree-ssa-loop-niter.h" | |
073c1fd5 | 44 | #include "tree-ssa-loop.h" |
45 | #include "tree-into-ssa.h" | |
69ee5dbb | 46 | #include "tree-ssa.h" |
b9ed1410 | 47 | #include "dumpfile.h" |
d09bc815 | 48 | #include "gimple-pretty-print.h" |
06598532 | 49 | #include "cfgloop.h" |
b9ed1410 | 50 | #include "tree-pass.h" /* ??? for TODO_update_ssa but this isn't a pass. */ |
06598532 | 51 | #include "tree-scalar-evolution.h" |
b30560de | 52 | #include "params.h" |
bc8bb825 | 53 | #include "tree-inline.h" |
5fa90eea | 54 | #include "langhooks.h" |
06598532 | 55 | |
ed7e2206 | 56 | /* All bitmaps for rewriting into loop-closed SSA go on this obstack, |
57 | so that we can free them all at once. */ | |
58 | static bitmap_obstack loop_renamer_obstack; | |
59 | ||
bb445479 | 60 | /* Creates an induction variable with value BASE + STEP * iteration in LOOP. |
61 | It is expected that neither BASE nor STEP are shared with other expressions | |
62 | (unless the sharing rules allow this). Use VAR as a base var_decl for it | |
63 | (if NULL, a new temporary will be created). The increment will occur at | |
48e1416a | 64 | INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and |
f98505bb | 65 | AFTER can be computed using standard_iv_increment_position. The ssa versions |
bb445479 | 66 | of the variable before and after increment will be stored in VAR_BEFORE and |
67 | VAR_AFTER (unless they are NULL). */ | |
68 | ||
69 | void | |
70 | create_iv (tree base, tree step, tree var, struct loop *loop, | |
75a70cf9 | 71 | gimple_stmt_iterator *incr_pos, bool after, |
bb445479 | 72 | tree *var_before, tree *var_after) |
73 | { | |
75a70cf9 | 74 | gimple stmt; |
75 | tree initial, step1; | |
76 | gimple_seq stmts; | |
bb445479 | 77 | tree vb, va; |
78 | enum tree_code incr_op = PLUS_EXPR; | |
651874e1 | 79 | edge pe = loop_preheader_edge (loop); |
bb445479 | 80 | |
03d37e4e | 81 | if (var != NULL_TREE) |
82 | { | |
83 | vb = make_ssa_name (var, NULL); | |
84 | va = make_ssa_name (var, NULL); | |
85 | } | |
86 | else | |
87 | { | |
88 | vb = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp"); | |
89 | va = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp"); | |
90 | } | |
bb445479 | 91 | if (var_before) |
92 | *var_before = vb; | |
bb445479 | 93 | if (var_after) |
94 | *var_after = va; | |
95 | ||
96 | /* For easier readability of the created code, produce MINUS_EXPRs | |
97 | when suitable. */ | |
98 | if (TREE_CODE (step) == INTEGER_CST) | |
99 | { | |
100 | if (TYPE_UNSIGNED (TREE_TYPE (step))) | |
101 | { | |
49d00087 | 102 | step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); |
bb445479 | 103 | if (tree_int_cst_lt (step1, step)) |
104 | { | |
105 | incr_op = MINUS_EXPR; | |
106 | step = step1; | |
107 | } | |
108 | } | |
109 | else | |
110 | { | |
add6ee5e | 111 | bool ovf; |
112 | ||
113 | if (!tree_expr_nonnegative_warnv_p (step, &ovf) | |
bb445479 | 114 | && may_negate_without_overflow_p (step)) |
115 | { | |
116 | incr_op = MINUS_EXPR; | |
49d00087 | 117 | step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); |
bb445479 | 118 | } |
119 | } | |
120 | } | |
0de36bdb | 121 | if (POINTER_TYPE_P (TREE_TYPE (base))) |
122 | { | |
86f2ad37 | 123 | if (TREE_CODE (base) == ADDR_EXPR) |
124 | mark_addressable (TREE_OPERAND (base, 0)); | |
a0553bff | 125 | step = convert_to_ptrofftype (step); |
0de36bdb | 126 | if (incr_op == MINUS_EXPR) |
a0553bff | 127 | step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); |
0de36bdb | 128 | incr_op = POINTER_PLUS_EXPR; |
129 | } | |
651874e1 | 130 | /* Gimplify the step if necessary. We put the computations in front of the |
131 | loop (i.e. the step should be loop invariant). */ | |
06240723 | 132 | step = force_gimple_operand (step, &stmts, true, NULL_TREE); |
651874e1 | 133 | if (stmts) |
75a70cf9 | 134 | gsi_insert_seq_on_edge_immediate (pe, stmts); |
651874e1 | 135 | |
75a70cf9 | 136 | stmt = gimple_build_assign_with_ops (incr_op, va, vb, step); |
bb445479 | 137 | if (after) |
75a70cf9 | 138 | gsi_insert_after (incr_pos, stmt, GSI_NEW_STMT); |
bb445479 | 139 | else |
75a70cf9 | 140 | gsi_insert_before (incr_pos, stmt, GSI_NEW_STMT); |
bb445479 | 141 | |
dec41e98 | 142 | initial = force_gimple_operand (base, &stmts, true, var); |
143 | if (stmts) | |
75a70cf9 | 144 | gsi_insert_seq_on_edge_immediate (pe, stmts); |
bb445479 | 145 | |
146 | stmt = create_phi_node (vb, loop->header); | |
60d535d2 | 147 | add_phi_arg (stmt, initial, loop_preheader_edge (loop), UNKNOWN_LOCATION); |
148 | add_phi_arg (stmt, va, loop_latch_edge (loop), UNKNOWN_LOCATION); | |
bb445479 | 149 | } |
150 | ||
4fb07d00 | 151 | /* Return the innermost superloop LOOP of USE_LOOP that is a superloop of |
d09bc815 | 152 | both DEF_LOOP and USE_LOOP. */ |
153 | ||
154 | static inline struct loop * | |
155 | find_sibling_superloop (struct loop *use_loop, struct loop *def_loop) | |
156 | { | |
157 | unsigned ud = loop_depth (use_loop); | |
158 | unsigned dd = loop_depth (def_loop); | |
159 | gcc_assert (ud > 0 && dd > 0); | |
160 | if (ud > dd) | |
161 | use_loop = superloop_at_depth (use_loop, dd); | |
162 | if (ud < dd) | |
163 | def_loop = superloop_at_depth (def_loop, ud); | |
164 | while (loop_outer (use_loop) != loop_outer (def_loop)) | |
165 | { | |
166 | use_loop = loop_outer (use_loop); | |
167 | def_loop = loop_outer (def_loop); | |
168 | gcc_assert (use_loop && def_loop); | |
169 | } | |
170 | return use_loop; | |
171 | } | |
172 | ||
173 | /* DEF_BB is a basic block containing a DEF that needs rewriting into | |
174 | loop-closed SSA form. USE_BLOCKS is the set of basic blocks containing | |
175 | uses of DEF that "escape" from the loop containing DEF_BB (i.e. blocks in | |
176 | USE_BLOCKS are dominated by DEF_BB but not in the loop father of DEF_B). | |
177 | ALL_EXITS[I] is the set of all basic blocks that exit loop I. | |
178 | ||
179 | Compute the subset of LOOP_EXITS that exit the loop containing DEF_BB | |
180 | or one of its loop fathers, in which DEF is live. This set is returned | |
181 | in the bitmap LIVE_EXITS. | |
182 | ||
183 | Instead of computing the complete livein set of the def, we use the loop | |
184 | nesting tree as a form of poor man's structure analysis. This greatly | |
185 | speeds up the analysis, which is important because this function may be | |
186 | called on all SSA names that need rewriting, one at a time. */ | |
06598532 | 187 | |
188 | static void | |
d09bc815 | 189 | compute_live_loop_exits (bitmap live_exits, bitmap use_blocks, |
190 | bitmap *loop_exits, basic_block def_bb) | |
06598532 | 191 | { |
d09bc815 | 192 | unsigned i; |
193 | bitmap_iterator bi; | |
d09bc815 | 194 | struct loop *def_loop = def_bb->loop_father; |
195 | unsigned def_loop_depth = loop_depth (def_loop); | |
196 | bitmap def_loop_exits; | |
197 | ||
198 | /* Normally the work list size is bounded by the number of basic | |
199 | blocks in the largest loop. We don't know this number, but we | |
200 | can be fairly sure that it will be relatively small. */ | |
c2078b80 | 201 | auto_vec<basic_block> worklist (MAX (8, n_basic_blocks_for_fn (cfun) / 128)); |
d09bc815 | 202 | |
203 | EXECUTE_IF_SET_IN_BITMAP (use_blocks, 0, i, bi) | |
204 | { | |
f5a6b05f | 205 | basic_block use_bb = BASIC_BLOCK_FOR_FN (cfun, i); |
d09bc815 | 206 | struct loop *use_loop = use_bb->loop_father; |
207 | gcc_checking_assert (def_loop != use_loop | |
208 | && ! flow_loop_nested_p (def_loop, use_loop)); | |
209 | if (! flow_loop_nested_p (use_loop, def_loop)) | |
210 | use_bb = find_sibling_superloop (use_loop, def_loop)->header; | |
211 | if (bitmap_set_bit (live_exits, use_bb->index)) | |
f1f41a6c | 212 | worklist.safe_push (use_bb); |
d09bc815 | 213 | } |
214 | ||
215 | /* Iterate until the worklist is empty. */ | |
f1f41a6c | 216 | while (! worklist.is_empty ()) |
d09bc815 | 217 | { |
218 | edge e; | |
219 | edge_iterator ei; | |
220 | ||
221 | /* Pull a block off the worklist. */ | |
f1f41a6c | 222 | basic_block bb = worklist.pop (); |
d09bc815 | 223 | |
224 | /* Make sure we have at least enough room in the work list | |
225 | for all predecessors of this block. */ | |
f1f41a6c | 226 | worklist.reserve (EDGE_COUNT (bb->preds)); |
d09bc815 | 227 | |
228 | /* For each predecessor block. */ | |
229 | FOR_EACH_EDGE (e, ei, bb->preds) | |
230 | { | |
231 | basic_block pred = e->src; | |
232 | struct loop *pred_loop = pred->loop_father; | |
233 | unsigned pred_loop_depth = loop_depth (pred_loop); | |
234 | bool pred_visited; | |
235 | ||
236 | /* We should have met DEF_BB along the way. */ | |
34154e27 | 237 | gcc_assert (pred != ENTRY_BLOCK_PTR_FOR_FN (cfun)); |
d09bc815 | 238 | |
239 | if (pred_loop_depth >= def_loop_depth) | |
240 | { | |
241 | if (pred_loop_depth > def_loop_depth) | |
242 | pred_loop = superloop_at_depth (pred_loop, def_loop_depth); | |
243 | /* If we've reached DEF_LOOP, our train ends here. */ | |
244 | if (pred_loop == def_loop) | |
245 | continue; | |
246 | } | |
247 | else if (! flow_loop_nested_p (pred_loop, def_loop)) | |
248 | pred = find_sibling_superloop (pred_loop, def_loop)->header; | |
249 | ||
250 | /* Add PRED to the LIVEIN set. PRED_VISITED is true if | |
251 | we had already added PRED to LIVEIN before. */ | |
252 | pred_visited = !bitmap_set_bit (live_exits, pred->index); | |
253 | ||
254 | /* If we have visited PRED before, don't add it to the worklist. | |
255 | If BB dominates PRED, then we're probably looking at a loop. | |
256 | We're only interested in looking up in the dominance tree | |
257 | because DEF_BB dominates all the uses. */ | |
258 | if (pred_visited || dominated_by_p (CDI_DOMINATORS, pred, bb)) | |
259 | continue; | |
260 | ||
f1f41a6c | 261 | worklist.quick_push (pred); |
d09bc815 | 262 | } |
263 | } | |
d09bc815 | 264 | |
265 | def_loop_exits = BITMAP_ALLOC (&loop_renamer_obstack); | |
266 | for (struct loop *loop = def_loop; | |
267 | loop != current_loops->tree_root; | |
268 | loop = loop_outer (loop)) | |
269 | bitmap_ior_into (def_loop_exits, loop_exits[loop->num]); | |
270 | bitmap_and_into (live_exits, def_loop_exits); | |
271 | BITMAP_FREE (def_loop_exits); | |
272 | } | |
273 | ||
274 | /* Add a loop-closing PHI for VAR in basic block EXIT. */ | |
275 | ||
276 | static void | |
277 | add_exit_phi (basic_block exit, tree var) | |
278 | { | |
279 | gimple phi; | |
06598532 | 280 | edge e; |
cd665a06 | 281 | edge_iterator ei; |
06598532 | 282 | |
d09bc815 | 283 | #ifdef ENABLE_CHECKING |
284 | /* Check that at least one of the edges entering the EXIT block exits | |
285 | the loop, or a superloop of that loop, that VAR is defined in. */ | |
286 | gimple def_stmt = SSA_NAME_DEF_STMT (var); | |
287 | basic_block def_bb = gimple_bb (def_stmt); | |
cd665a06 | 288 | FOR_EACH_EDGE (e, ei, exit->preds) |
06598532 | 289 | { |
d09bc815 | 290 | struct loop *aloop = find_common_loop (def_bb->loop_father, |
291 | e->src->loop_father); | |
292 | if (!flow_bb_inside_loop_p (aloop, e->dest)) | |
06598532 | 293 | break; |
294 | } | |
295 | ||
d09bc815 | 296 | gcc_checking_assert (e); |
297 | #endif | |
06598532 | 298 | |
9c06f260 | 299 | phi = create_phi_node (NULL_TREE, exit); |
d09bc815 | 300 | create_new_def_for (var, phi, gimple_phi_result_ptr (phi)); |
cd665a06 | 301 | FOR_EACH_EDGE (e, ei, exit->preds) |
d09bc815 | 302 | add_phi_arg (phi, var, e, UNKNOWN_LOCATION); |
303 | ||
304 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
305 | { | |
306 | fprintf (dump_file, ";; Created LCSSA PHI: "); | |
307 | print_gimple_stmt (dump_file, phi, 0, dump_flags); | |
308 | } | |
06598532 | 309 | } |
310 | ||
311 | /* Add exit phis for VAR that is used in LIVEIN. | |
d09bc815 | 312 | Exits of the loops are stored in LOOP_EXITS. */ |
06598532 | 313 | |
314 | static void | |
d09bc815 | 315 | add_exit_phis_var (tree var, bitmap use_blocks, bitmap *loop_exits) |
06598532 | 316 | { |
4f917ffe | 317 | unsigned index; |
0cc4271a | 318 | bitmap_iterator bi; |
d09bc815 | 319 | basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (var)); |
320 | bitmap live_exits = BITMAP_ALLOC (&loop_renamer_obstack); | |
06598532 | 321 | |
cf230d5d | 322 | gcc_checking_assert (! bitmap_bit_p (use_blocks, def_bb->index)); |
06598532 | 323 | |
d09bc815 | 324 | compute_live_loop_exits (live_exits, use_blocks, loop_exits, def_bb); |
06598532 | 325 | |
d09bc815 | 326 | EXECUTE_IF_SET_IN_BITMAP (live_exits, 0, index, bi) |
0cc4271a | 327 | { |
f5a6b05f | 328 | add_exit_phi (BASIC_BLOCK_FOR_FN (cfun, index), var); |
0cc4271a | 329 | } |
ed7e2206 | 330 | |
d09bc815 | 331 | BITMAP_FREE (live_exits); |
06598532 | 332 | } |
333 | ||
334 | /* Add exit phis for the names marked in NAMES_TO_RENAME. | |
335 | Exits of the loops are stored in EXITS. Sets of blocks where the ssa | |
336 | names are used are stored in USE_BLOCKS. */ | |
337 | ||
338 | static void | |
d09bc815 | 339 | add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap *loop_exits) |
06598532 | 340 | { |
341 | unsigned i; | |
0cc4271a | 342 | bitmap_iterator bi; |
06598532 | 343 | |
0cc4271a | 344 | EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i, bi) |
06598532 | 345 | { |
346 | add_exit_phis_var (ssa_name (i), use_blocks[i], loop_exits); | |
0cc4271a | 347 | } |
06598532 | 348 | } |
349 | ||
d09bc815 | 350 | /* Fill the array of bitmaps LOOP_EXITS with all loop exit edge targets. */ |
06598532 | 351 | |
d09bc815 | 352 | static void |
353 | get_loops_exits (bitmap *loop_exits) | |
06598532 | 354 | { |
d09bc815 | 355 | struct loop *loop; |
356 | unsigned j; | |
06598532 | 357 | edge e; |
358 | ||
f21d4d00 | 359 | FOR_EACH_LOOP (loop, 0) |
06598532 | 360 | { |
f1f41a6c | 361 | vec<edge> exit_edges = get_loop_exit_edges (loop); |
d09bc815 | 362 | loop_exits[loop->num] = BITMAP_ALLOC (&loop_renamer_obstack); |
f1f41a6c | 363 | FOR_EACH_VEC_ELT (exit_edges, j, e) |
d09bc815 | 364 | bitmap_set_bit (loop_exits[loop->num], e->dest->index); |
f1f41a6c | 365 | exit_edges.release (); |
06598532 | 366 | } |
06598532 | 367 | } |
368 | ||
369 | /* For USE in BB, if it is used outside of the loop it is defined in, | |
370 | mark it for rewrite. Record basic block BB where it is used | |
095dcfa3 | 371 | to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap. */ |
06598532 | 372 | |
373 | static void | |
095dcfa3 | 374 | find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks, |
375 | bitmap need_phis) | |
06598532 | 376 | { |
377 | unsigned ver; | |
378 | basic_block def_bb; | |
379 | struct loop *def_loop; | |
380 | ||
381 | if (TREE_CODE (use) != SSA_NAME) | |
382 | return; | |
383 | ||
384 | ver = SSA_NAME_VERSION (use); | |
75a70cf9 | 385 | def_bb = gimple_bb (SSA_NAME_DEF_STMT (use)); |
06598532 | 386 | if (!def_bb) |
387 | return; | |
388 | def_loop = def_bb->loop_father; | |
389 | ||
d88fd237 | 390 | /* If the definition is not inside a loop, it is not interesting. */ |
9e3536f4 | 391 | if (!loop_outer (def_loop)) |
06598532 | 392 | return; |
393 | ||
d88fd237 | 394 | /* If the use is not outside of the loop it is defined in, it is not |
395 | interesting. */ | |
396 | if (flow_bb_inside_loop_p (def_loop, bb)) | |
397 | return; | |
398 | ||
ed7e2206 | 399 | /* If we're seeing VER for the first time, we still have to allocate |
400 | a bitmap for its uses. */ | |
401 | if (bitmap_set_bit (need_phis, ver)) | |
402 | use_blocks[ver] = BITMAP_ALLOC (&loop_renamer_obstack); | |
06598532 | 403 | bitmap_set_bit (use_blocks[ver], bb->index); |
06598532 | 404 | } |
405 | ||
406 | /* For uses in STMT, mark names that are used outside of the loop they are | |
407 | defined to rewrite. Record the set of blocks in that the ssa | |
095dcfa3 | 408 | names are defined to USE_BLOCKS and the ssa names themselves to |
409 | NEED_PHIS. */ | |
06598532 | 410 | |
411 | static void | |
75a70cf9 | 412 | find_uses_to_rename_stmt (gimple stmt, bitmap *use_blocks, bitmap need_phis) |
06598532 | 413 | { |
43daa21e | 414 | ssa_op_iter iter; |
415 | tree var; | |
75a70cf9 | 416 | basic_block bb = gimple_bb (stmt); |
06598532 | 417 | |
9845d120 | 418 | if (is_gimple_debug (stmt)) |
419 | return; | |
420 | ||
5789f1f8 | 421 | FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) |
095dcfa3 | 422 | find_uses_to_rename_use (bb, var, use_blocks, need_phis); |
06598532 | 423 | } |
424 | ||
053fdd99 | 425 | /* Marks names that are used in BB and outside of the loop they are |
426 | defined in for rewrite. Records the set of blocks in that the ssa | |
095dcfa3 | 427 | names are defined to USE_BLOCKS. Record the SSA names that will |
428 | need exit PHIs in NEED_PHIS. */ | |
06598532 | 429 | |
430 | static void | |
095dcfa3 | 431 | find_uses_to_rename_bb (basic_block bb, bitmap *use_blocks, bitmap need_phis) |
06598532 | 432 | { |
75a70cf9 | 433 | gimple_stmt_iterator bsi; |
053fdd99 | 434 | edge e; |
435 | edge_iterator ei; | |
06598532 | 436 | |
053fdd99 | 437 | FOR_EACH_EDGE (e, ei, bb->succs) |
75a70cf9 | 438 | for (bsi = gsi_start_phis (e->dest); !gsi_end_p (bsi); gsi_next (&bsi)) |
d09bc815 | 439 | { |
440 | gimple phi = gsi_stmt (bsi); | |
5789f1f8 | 441 | if (! virtual_operand_p (gimple_phi_result (phi))) |
442 | find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e), | |
443 | use_blocks, need_phis); | |
d09bc815 | 444 | } |
48e1416a | 445 | |
75a70cf9 | 446 | for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
447 | find_uses_to_rename_stmt (gsi_stmt (bsi), use_blocks, need_phis); | |
053fdd99 | 448 | } |
48e1416a | 449 | |
053fdd99 | 450 | /* Marks names that are used outside of the loop they are defined in |
451 | for rewrite. Records the set of blocks in that the ssa | |
452 | names are defined to USE_BLOCKS. If CHANGED_BBS is not NULL, | |
453 | scan only blocks in this set. */ | |
454 | ||
455 | static void | |
095dcfa3 | 456 | find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis) |
053fdd99 | 457 | { |
458 | basic_block bb; | |
459 | unsigned index; | |
460 | bitmap_iterator bi; | |
06598532 | 461 | |
f55f91f5 | 462 | if (changed_bbs) |
463 | EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi) | |
f5a6b05f | 464 | find_uses_to_rename_bb (BASIC_BLOCK_FOR_FN (cfun, index), use_blocks, need_phis); |
053fdd99 | 465 | else |
fc00614f | 466 | FOR_EACH_BB_FN (bb, cfun) |
f55f91f5 | 467 | find_uses_to_rename_bb (bb, use_blocks, need_phis); |
06598532 | 468 | } |
469 | ||
470 | /* Rewrites the program into a loop closed ssa form -- i.e. inserts extra | |
471 | phi nodes to ensure that no variable is used outside the loop it is | |
472 | defined in. | |
473 | ||
474 | This strengthening of the basic ssa form has several advantages: | |
475 | ||
476 | 1) Updating it during unrolling/peeling/versioning is trivial, since | |
477 | we do not need to care about the uses outside of the loop. | |
cf230d5d | 478 | The same applies to virtual operands which are also rewritten into |
479 | loop closed SSA form. Note that virtual operands are always live | |
480 | until function exit. | |
06598532 | 481 | 2) The behavior of all uses of an induction variable is the same. |
482 | Without this, you need to distinguish the case when the variable | |
483 | is used outside of the loop it is defined in, for example | |
484 | ||
485 | for (i = 0; i < 100; i++) | |
486 | { | |
487 | for (j = 0; j < 100; j++) | |
488 | { | |
489 | k = i + j; | |
490 | use1 (k); | |
491 | } | |
492 | use2 (k); | |
493 | } | |
494 | ||
495 | Looking from the outer loop with the normal SSA form, the first use of k | |
496 | is not well-behaved, while the second one is an induction variable with | |
053fdd99 | 497 | base 99 and step 1. |
48e1416a | 498 | |
053fdd99 | 499 | If CHANGED_BBS is not NULL, we look for uses outside loops only in |
095dcfa3 | 500 | the basic blocks in this set. |
501 | ||
502 | UPDATE_FLAG is used in the call to update_ssa. See | |
503 | TODO_update_ssa* for documentation. */ | |
06598532 | 504 | |
505 | void | |
095dcfa3 | 506 | rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag) |
06598532 | 507 | { |
06598532 | 508 | bitmap *use_blocks; |
d8a0d6b8 | 509 | bitmap names_to_rename; |
510 | ||
f24ec26f | 511 | loops_state_set (LOOP_CLOSED_SSA); |
41f75a99 | 512 | if (number_of_loops (cfun) <= 1) |
d8a0d6b8 | 513 | return; |
514 | ||
d09bc815 | 515 | /* If the pass has caused the SSA form to be out-of-date, update it |
516 | now. */ | |
517 | update_ssa (update_flag); | |
518 | ||
ed7e2206 | 519 | bitmap_obstack_initialize (&loop_renamer_obstack); |
520 | ||
ed7e2206 | 521 | names_to_rename = BITMAP_ALLOC (&loop_renamer_obstack); |
06598532 | 522 | |
ed7e2206 | 523 | /* Uses of names to rename. We don't have to initialize this array, |
524 | because we know that we will only have entries for the SSA names | |
525 | in NAMES_TO_RENAME. */ | |
91442a6f | 526 | use_blocks = XNEWVEC (bitmap, num_ssa_names); |
06598532 | 527 | |
528 | /* Find the uses outside loops. */ | |
095dcfa3 | 529 | find_uses_to_rename (changed_bbs, use_blocks, names_to_rename); |
053fdd99 | 530 | |
c8498e04 | 531 | if (!bitmap_empty_p (names_to_rename)) |
532 | { | |
533 | /* An array of bitmaps where LOOP_EXITS[I] is the set of basic blocks | |
534 | that are the destination of an edge exiting loop number I. */ | |
41f75a99 | 535 | bitmap *loop_exits = XNEWVEC (bitmap, number_of_loops (cfun)); |
c8498e04 | 536 | get_loops_exits (loop_exits); |
537 | ||
538 | /* Add the PHI nodes on exits of the loops for the names we need to | |
539 | rewrite. */ | |
540 | add_exit_phis (names_to_rename, use_blocks, loop_exits); | |
541 | ||
542 | free (loop_exits); | |
543 | ||
544 | /* Fix up all the names found to be used outside their original | |
545 | loops. */ | |
546 | update_ssa (TODO_update_ssa); | |
547 | } | |
06598532 | 548 | |
ed7e2206 | 549 | bitmap_obstack_release (&loop_renamer_obstack); |
06598532 | 550 | free (use_blocks); |
06598532 | 551 | } |
552 | ||
553 | /* Check invariants of the loop closed ssa form for the USE in BB. */ | |
554 | ||
555 | static void | |
556 | check_loop_closed_ssa_use (basic_block bb, tree use) | |
557 | { | |
75a70cf9 | 558 | gimple def; |
06598532 | 559 | basic_block def_bb; |
48e1416a | 560 | |
7c782c9b | 561 | if (TREE_CODE (use) != SSA_NAME || virtual_operand_p (use)) |
06598532 | 562 | return; |
563 | ||
564 | def = SSA_NAME_DEF_STMT (use); | |
75a70cf9 | 565 | def_bb = gimple_bb (def); |
8c0963c4 | 566 | gcc_assert (!def_bb |
567 | || flow_bb_inside_loop_p (def_bb->loop_father, bb)); | |
06598532 | 568 | } |
569 | ||
570 | /* Checks invariants of loop closed ssa form in statement STMT in BB. */ | |
571 | ||
572 | static void | |
75a70cf9 | 573 | check_loop_closed_ssa_stmt (basic_block bb, gimple stmt) |
06598532 | 574 | { |
43daa21e | 575 | ssa_op_iter iter; |
576 | tree var; | |
06598532 | 577 | |
9845d120 | 578 | if (is_gimple_debug (stmt)) |
579 | return; | |
580 | ||
ed7e2206 | 581 | FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) |
43daa21e | 582 | check_loop_closed_ssa_use (bb, var); |
06598532 | 583 | } |
584 | ||
ca77c6ec | 585 | /* Checks that invariants of the loop closed ssa form are preserved. |
586 | Call verify_ssa when VERIFY_SSA_P is true. */ | |
06598532 | 587 | |
4b987fac | 588 | DEBUG_FUNCTION void |
ca77c6ec | 589 | verify_loop_closed_ssa (bool verify_ssa_p) |
06598532 | 590 | { |
591 | basic_block bb; | |
75a70cf9 | 592 | gimple_stmt_iterator bsi; |
593 | gimple phi; | |
594 | edge e; | |
595 | edge_iterator ei; | |
06598532 | 596 | |
41f75a99 | 597 | if (number_of_loops (cfun) <= 1) |
095dcfa3 | 598 | return; |
599 | ||
ca77c6ec | 600 | if (verify_ssa_p) |
601 | verify_ssa (false); | |
06598532 | 602 | |
4b366dd3 | 603 | timevar_push (TV_VERIFY_LOOP_CLOSED); |
604 | ||
fc00614f | 605 | FOR_EACH_BB_FN (bb, cfun) |
06598532 | 606 | { |
75a70cf9 | 607 | for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
608 | { | |
609 | phi = gsi_stmt (bsi); | |
610 | FOR_EACH_EDGE (e, ei, bb->preds) | |
611 | check_loop_closed_ssa_use (e->src, | |
612 | PHI_ARG_DEF_FROM_EDGE (phi, e)); | |
613 | } | |
06598532 | 614 | |
75a70cf9 | 615 | for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
616 | check_loop_closed_ssa_stmt (bb, gsi_stmt (bsi)); | |
06598532 | 617 | } |
4b366dd3 | 618 | |
619 | timevar_pop (TV_VERIFY_LOOP_CLOSED); | |
06598532 | 620 | } |
dec41e98 | 621 | |
622 | /* Split loop exit edge EXIT. The things are a bit complicated by a need to | |
28c92cbb | 623 | preserve the loop closed ssa form. The newly created block is returned. */ |
dec41e98 | 624 | |
28c92cbb | 625 | basic_block |
dec41e98 | 626 | split_loop_exit_edge (edge exit) |
627 | { | |
628 | basic_block dest = exit->dest; | |
88e6f696 | 629 | basic_block bb = split_edge (exit); |
75a70cf9 | 630 | gimple phi, new_phi; |
631 | tree new_name, name; | |
dec41e98 | 632 | use_operand_p op_p; |
75a70cf9 | 633 | gimple_stmt_iterator psi; |
efbcb6de | 634 | source_location locus; |
dec41e98 | 635 | |
75a70cf9 | 636 | for (psi = gsi_start_phis (dest); !gsi_end_p (psi); gsi_next (&psi)) |
dec41e98 | 637 | { |
75a70cf9 | 638 | phi = gsi_stmt (psi); |
ea091dfd | 639 | op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb)); |
efbcb6de | 640 | locus = gimple_phi_arg_location_from_edge (phi, single_succ_edge (bb)); |
dec41e98 | 641 | |
b2ca91ff | 642 | name = USE_FROM_PTR (op_p); |
643 | ||
4fb5e5ca | 644 | /* If the argument of the PHI node is a constant, we do not need |
b2ca91ff | 645 | to keep it inside loop. */ |
646 | if (TREE_CODE (name) != SSA_NAME) | |
647 | continue; | |
648 | ||
649 | /* Otherwise create an auxiliary phi node that will copy the value | |
4fb5e5ca | 650 | of the SSA name out of the loop. */ |
b2ca91ff | 651 | new_name = duplicate_ssa_name (name, NULL); |
dec41e98 | 652 | new_phi = create_phi_node (new_name, bb); |
60d535d2 | 653 | add_phi_arg (new_phi, name, exit, locus); |
dec41e98 | 654 | SET_USE (op_p, new_name); |
655 | } | |
28c92cbb | 656 | |
657 | return bb; | |
dec41e98 | 658 | } |
659 | ||
dec41e98 | 660 | /* Returns the basic block in that statements should be emitted for induction |
661 | variables incremented at the end of the LOOP. */ | |
662 | ||
663 | basic_block | |
664 | ip_end_pos (struct loop *loop) | |
665 | { | |
666 | return loop->latch; | |
667 | } | |
668 | ||
669 | /* Returns the basic block in that statements should be emitted for induction | |
670 | variables incremented just before exit condition of a LOOP. */ | |
671 | ||
672 | basic_block | |
673 | ip_normal_pos (struct loop *loop) | |
674 | { | |
75a70cf9 | 675 | gimple last; |
dec41e98 | 676 | basic_block bb; |
677 | edge exit; | |
678 | ||
ea091dfd | 679 | if (!single_pred_p (loop->latch)) |
dec41e98 | 680 | return NULL; |
681 | ||
ea091dfd | 682 | bb = single_pred (loop->latch); |
dec41e98 | 683 | last = last_stmt (bb); |
d92f9312 | 684 | if (!last |
75a70cf9 | 685 | || gimple_code (last) != GIMPLE_COND) |
dec41e98 | 686 | return NULL; |
687 | ||
cd665a06 | 688 | exit = EDGE_SUCC (bb, 0); |
dec41e98 | 689 | if (exit->dest == loop->latch) |
cd665a06 | 690 | exit = EDGE_SUCC (bb, 1); |
dec41e98 | 691 | |
692 | if (flow_bb_inside_loop_p (loop, exit->dest)) | |
693 | return NULL; | |
694 | ||
695 | return bb; | |
696 | } | |
697 | ||
698 | /* Stores the standard position for induction variable increment in LOOP | |
699 | (just before the exit condition if it is available and latch block is empty, | |
700 | end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if | |
701 | the increment should be inserted after *BSI. */ | |
702 | ||
703 | void | |
75a70cf9 | 704 | standard_iv_increment_position (struct loop *loop, gimple_stmt_iterator *bsi, |
dec41e98 | 705 | bool *insert_after) |
706 | { | |
707 | basic_block bb = ip_normal_pos (loop), latch = ip_end_pos (loop); | |
75a70cf9 | 708 | gimple last = last_stmt (latch); |
dec41e98 | 709 | |
710 | if (!bb | |
75a70cf9 | 711 | || (last && gimple_code (last) != GIMPLE_LABEL)) |
dec41e98 | 712 | { |
75a70cf9 | 713 | *bsi = gsi_last_bb (latch); |
dec41e98 | 714 | *insert_after = true; |
715 | } | |
716 | else | |
717 | { | |
75a70cf9 | 718 | *bsi = gsi_last_bb (bb); |
dec41e98 | 719 | *insert_after = false; |
720 | } | |
721 | } | |
e12d0591 | 722 | |
723 | /* Copies phi node arguments for duplicated blocks. The index of the first | |
724 | duplicated block is FIRST_NEW_BLOCK. */ | |
725 | ||
726 | static void | |
727 | copy_phi_node_args (unsigned first_new_block) | |
728 | { | |
729 | unsigned i; | |
730 | ||
fe672ac0 | 731 | for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++) |
f5a6b05f | 732 | BASIC_BLOCK_FOR_FN (cfun, i)->flags |= BB_DUPLICATED; |
e12d0591 | 733 | |
fe672ac0 | 734 | for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++) |
f5a6b05f | 735 | add_phi_args_after_copy_bb (BASIC_BLOCK_FOR_FN (cfun, i)); |
e12d0591 | 736 | |
fe672ac0 | 737 | for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++) |
f5a6b05f | 738 | BASIC_BLOCK_FOR_FN (cfun, i)->flags &= ~BB_DUPLICATED; |
e12d0591 | 739 | } |
740 | ||
e12d0591 | 741 | |
095dcfa3 | 742 | /* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also |
743 | updates the PHI nodes at start of the copied region. In order to | |
744 | achieve this, only loops whose exits all lead to the same location | |
745 | are handled. | |
e12d0591 | 746 | |
095dcfa3 | 747 | Notice that we do not completely update the SSA web after |
748 | duplication. The caller is responsible for calling update_ssa | |
749 | after the loop has been duplicated. */ | |
e12d0591 | 750 | |
751 | bool | |
75a70cf9 | 752 | gimple_duplicate_loop_to_header_edge (struct loop *loop, edge e, |
e12d0591 | 753 | unsigned int ndupl, sbitmap wont_exit, |
f1f41a6c | 754 | edge orig, vec<edge> *to_remove, |
f3c40e6d | 755 | int flags) |
e12d0591 | 756 | { |
757 | unsigned first_new_block; | |
e12d0591 | 758 | |
f24ec26f | 759 | if (!loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)) |
e12d0591 | 760 | return false; |
f24ec26f | 761 | if (!loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)) |
e12d0591 | 762 | return false; |
763 | ||
764 | #ifdef ENABLE_CHECKING | |
ea1c5c31 | 765 | /* ??? This forces needless update_ssa calls after processing each |
766 | loop instead of just once after processing all loops. We should | |
767 | instead verify that loop-closed SSA form is up-to-date for LOOP | |
768 | only (and possibly SSA form). For now just skip verifying if | |
769 | there are to-be renamed variables. */ | |
770 | if (!need_ssa_update_p (cfun) | |
771 | && loops_state_satisfies_p (LOOP_CLOSED_SSA)) | |
ca77c6ec | 772 | verify_loop_closed_ssa (true); |
e12d0591 | 773 | #endif |
774 | ||
fe672ac0 | 775 | first_new_block = last_basic_block_for_fn (cfun); |
7194de72 | 776 | if (!duplicate_loop_to_header_edge (loop, e, ndupl, wont_exit, |
f3c40e6d | 777 | orig, to_remove, flags)) |
e12d0591 | 778 | return false; |
779 | ||
780 | /* Readd the removed phi args for e. */ | |
44a46103 | 781 | flush_pending_stmts (e); |
e12d0591 | 782 | |
783 | /* Copy the phi node arguments. */ | |
784 | copy_phi_node_args (first_new_block); | |
785 | ||
e12d0591 | 786 | scev_reset (); |
e12d0591 | 787 | |
788 | return true; | |
789 | } | |
b30560de | 790 | |
b30560de | 791 | /* Returns true if we can unroll LOOP FACTOR times. Number |
792 | of iterations of the loop is returned in NITER. */ | |
793 | ||
794 | bool | |
795 | can_unroll_loop_p (struct loop *loop, unsigned factor, | |
796 | struct tree_niter_desc *niter) | |
797 | { | |
798 | edge exit; | |
799 | ||
800 | /* Check whether unrolling is possible. We only want to unroll loops | |
801 | for that we are able to determine number of iterations. We also | |
802 | want to split the extra iterations of the loop from its end, | |
803 | therefore we require that the loop has precisely one | |
804 | exit. */ | |
805 | ||
806 | exit = single_dom_exit (loop); | |
807 | if (!exit) | |
808 | return false; | |
809 | ||
810 | if (!number_of_iterations_exit (loop, exit, niter, false) | |
07392428 | 811 | || niter->cmp == ERROR_MARK |
812 | /* Scalar evolutions analysis might have copy propagated | |
813 | the abnormal ssa names into these expressions, hence | |
fa7637bd | 814 | emitting the computations based on them during loop |
07392428 | 815 | unrolling might create overlapping life ranges for |
816 | them, and failures in out-of-ssa. */ | |
817 | || contains_abnormal_ssa_name_p (niter->may_be_zero) | |
818 | || contains_abnormal_ssa_name_p (niter->control.base) | |
819 | || contains_abnormal_ssa_name_p (niter->control.step) | |
820 | || contains_abnormal_ssa_name_p (niter->bound)) | |
b30560de | 821 | return false; |
822 | ||
823 | /* And of course, we must be able to duplicate the loop. */ | |
824 | if (!can_duplicate_loop_p (loop)) | |
825 | return false; | |
826 | ||
827 | /* The final loop should be small enough. */ | |
bc8bb825 | 828 | if (tree_num_loop_insns (loop, &eni_size_weights) * factor |
b30560de | 829 | > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS)) |
830 | return false; | |
831 | ||
832 | return true; | |
833 | } | |
834 | ||
835 | /* Determines the conditions that control execution of LOOP unrolled FACTOR | |
836 | times. DESC is number of iterations of LOOP. ENTER_COND is set to | |
837 | condition that must be true if the main loop can be entered. | |
838 | EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing | |
839 | how the exit from the unrolled loop should be controlled. */ | |
840 | ||
841 | static void | |
842 | determine_exit_conditions (struct loop *loop, struct tree_niter_desc *desc, | |
843 | unsigned factor, tree *enter_cond, | |
844 | tree *exit_base, tree *exit_step, | |
845 | enum tree_code *exit_cmp, tree *exit_bound) | |
846 | { | |
75a70cf9 | 847 | gimple_seq stmts; |
b30560de | 848 | tree base = desc->control.base; |
849 | tree step = desc->control.step; | |
850 | tree bound = desc->bound; | |
e88bb328 | 851 | tree type = TREE_TYPE (step); |
b30560de | 852 | tree bigstep, delta; |
853 | tree min = lower_bound_in_type (type, type); | |
854 | tree max = upper_bound_in_type (type, type); | |
855 | enum tree_code cmp = desc->cmp; | |
856 | tree cond = boolean_true_node, assum; | |
857 | ||
a0553bff | 858 | /* For pointers, do the arithmetics in the type of step. */ |
e88bb328 | 859 | base = fold_convert (type, base); |
860 | bound = fold_convert (type, bound); | |
861 | ||
b30560de | 862 | *enter_cond = boolean_false_node; |
863 | *exit_base = NULL_TREE; | |
864 | *exit_step = NULL_TREE; | |
865 | *exit_cmp = ERROR_MARK; | |
866 | *exit_bound = NULL_TREE; | |
867 | gcc_assert (cmp != ERROR_MARK); | |
868 | ||
869 | /* We only need to be correct when we answer question | |
870 | "Do at least FACTOR more iterations remain?" in the unrolled loop. | |
871 | Thus, transforming BASE + STEP * i <> BOUND to | |
872 | BASE + STEP * i < BOUND is ok. */ | |
873 | if (cmp == NE_EXPR) | |
874 | { | |
875 | if (tree_int_cst_sign_bit (step)) | |
876 | cmp = GT_EXPR; | |
877 | else | |
878 | cmp = LT_EXPR; | |
879 | } | |
880 | else if (cmp == LT_EXPR) | |
881 | { | |
882 | gcc_assert (!tree_int_cst_sign_bit (step)); | |
883 | } | |
884 | else if (cmp == GT_EXPR) | |
885 | { | |
886 | gcc_assert (tree_int_cst_sign_bit (step)); | |
887 | } | |
888 | else | |
889 | gcc_unreachable (); | |
890 | ||
891 | /* The main body of the loop may be entered iff: | |
892 | ||
893 | 1) desc->may_be_zero is false. | |
894 | 2) it is possible to check that there are at least FACTOR iterations | |
895 | of the loop, i.e., BOUND - step * FACTOR does not overflow. | |
896 | 3) # of iterations is at least FACTOR */ | |
897 | ||
cd743a11 | 898 | if (!integer_zerop (desc->may_be_zero)) |
b30560de | 899 | cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, |
900 | invert_truthvalue (desc->may_be_zero), | |
901 | cond); | |
902 | ||
903 | bigstep = fold_build2 (MULT_EXPR, type, step, | |
904 | build_int_cst_type (type, factor)); | |
905 | delta = fold_build2 (MINUS_EXPR, type, bigstep, step); | |
906 | if (cmp == LT_EXPR) | |
907 | assum = fold_build2 (GE_EXPR, boolean_type_node, | |
908 | bound, | |
909 | fold_build2 (PLUS_EXPR, type, min, delta)); | |
910 | else | |
911 | assum = fold_build2 (LE_EXPR, boolean_type_node, | |
912 | bound, | |
913 | fold_build2 (PLUS_EXPR, type, max, delta)); | |
914 | cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond); | |
915 | ||
916 | bound = fold_build2 (MINUS_EXPR, type, bound, delta); | |
917 | assum = fold_build2 (cmp, boolean_type_node, base, bound); | |
918 | cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond); | |
919 | ||
920 | cond = force_gimple_operand (unshare_expr (cond), &stmts, false, NULL_TREE); | |
921 | if (stmts) | |
75a70cf9 | 922 | gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); |
b30560de | 923 | /* cond now may be a gimple comparison, which would be OK, but also any |
924 | other gimple rhs (say a && b). In this case we need to force it to | |
925 | operand. */ | |
926 | if (!is_gimple_condexpr (cond)) | |
927 | { | |
928 | cond = force_gimple_operand (cond, &stmts, true, NULL_TREE); | |
929 | if (stmts) | |
75a70cf9 | 930 | gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); |
b30560de | 931 | } |
932 | *enter_cond = cond; | |
933 | ||
934 | base = force_gimple_operand (unshare_expr (base), &stmts, true, NULL_TREE); | |
935 | if (stmts) | |
75a70cf9 | 936 | gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); |
b30560de | 937 | bound = force_gimple_operand (unshare_expr (bound), &stmts, true, NULL_TREE); |
938 | if (stmts) | |
75a70cf9 | 939 | gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); |
b30560de | 940 | |
941 | *exit_base = base; | |
942 | *exit_step = bigstep; | |
943 | *exit_cmp = cmp; | |
944 | *exit_bound = bound; | |
945 | } | |
946 | ||
611d2ac1 | 947 | /* Scales the frequencies of all basic blocks in LOOP that are strictly |
948 | dominated by BB by NUM/DEN. */ | |
949 | ||
950 | static void | |
951 | scale_dominated_blocks_in_loop (struct loop *loop, basic_block bb, | |
952 | int num, int den) | |
953 | { | |
954 | basic_block son; | |
955 | ||
956 | if (den == 0) | |
957 | return; | |
958 | ||
959 | for (son = first_dom_son (CDI_DOMINATORS, bb); | |
960 | son; | |
961 | son = next_dom_son (CDI_DOMINATORS, son)) | |
962 | { | |
963 | if (!flow_bb_inside_loop_p (loop, son)) | |
964 | continue; | |
965 | scale_bbs_frequencies_int (&son, 1, num, den); | |
966 | scale_dominated_blocks_in_loop (loop, son, num, den); | |
967 | } | |
968 | } | |
969 | ||
7194de72 | 970 | /* Unroll LOOP FACTOR times. DESC describes number of iterations of LOOP. |
971 | EXIT is the exit of the loop to that DESC corresponds. | |
972 | ||
b30560de | 973 | If N is number of iterations of the loop and MAY_BE_ZERO is the condition |
974 | under that loop exits in the first iteration even if N != 0, | |
48e1416a | 975 | |
b30560de | 976 | while (1) |
977 | { | |
978 | x = phi (init, next); | |
979 | ||
980 | pre; | |
981 | if (st) | |
982 | break; | |
983 | post; | |
984 | } | |
985 | ||
986 | becomes (with possibly the exit conditions formulated a bit differently, | |
987 | avoiding the need to create a new iv): | |
48e1416a | 988 | |
b30560de | 989 | if (MAY_BE_ZERO || N < FACTOR) |
990 | goto rest; | |
991 | ||
992 | do | |
993 | { | |
994 | x = phi (init, next); | |
995 | ||
996 | pre; | |
997 | post; | |
998 | pre; | |
999 | post; | |
1000 | ... | |
1001 | pre; | |
1002 | post; | |
1003 | N -= FACTOR; | |
48e1416a | 1004 | |
b30560de | 1005 | } while (N >= FACTOR); |
1006 | ||
1007 | rest: | |
1008 | init' = phi (init, x); | |
1009 | ||
1010 | while (1) | |
1011 | { | |
1012 | x = phi (init', next); | |
1013 | ||
1014 | pre; | |
1015 | if (st) | |
1016 | break; | |
1017 | post; | |
f6ae6f2a | 1018 | } |
48e1416a | 1019 | |
f6ae6f2a | 1020 | Before the loop is unrolled, TRANSFORM is called for it (only for the |
1021 | unrolled loop, but not for its versioned copy). DATA is passed to | |
1022 | TRANSFORM. */ | |
b30560de | 1023 | |
7cef6c97 | 1024 | /* Probability in % that the unrolled loop is entered. Just a guess. */ |
1025 | #define PROB_UNROLLED_LOOP_ENTERED 90 | |
1026 | ||
b30560de | 1027 | void |
f6ae6f2a | 1028 | tree_transform_and_unroll_loop (struct loop *loop, unsigned factor, |
1029 | edge exit, struct tree_niter_desc *desc, | |
1030 | transform_callback transform, | |
1031 | void *data) | |
b30560de | 1032 | { |
75a70cf9 | 1033 | gimple exit_if; |
1034 | tree ctr_before, ctr_after; | |
b30560de | 1035 | tree enter_main_cond, exit_base, exit_step, exit_bound; |
1036 | enum tree_code exit_cmp; | |
75a70cf9 | 1037 | gimple phi_old_loop, phi_new_loop, phi_rest; |
1038 | gimple_stmt_iterator psi_old_loop, psi_new_loop; | |
ec11736b | 1039 | tree init, next, new_init; |
b30560de | 1040 | struct loop *new_loop; |
1041 | basic_block rest, exit_bb; | |
1042 | edge old_entry, new_entry, old_latch, precond_edge, new_exit; | |
611d2ac1 | 1043 | edge new_nonexit, e; |
75a70cf9 | 1044 | gimple_stmt_iterator bsi; |
b30560de | 1045 | use_operand_p op; |
1046 | bool ok; | |
7cef6c97 | 1047 | unsigned est_niter, prob_entry, scale_unrolled, scale_rest, freq_e, freq_h; |
611d2ac1 | 1048 | unsigned new_est_niter, i, prob; |
89c8b802 | 1049 | unsigned irr = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP; |
b30560de | 1050 | sbitmap wont_exit; |
c2078b80 | 1051 | auto_vec<edge> to_remove; |
b30560de | 1052 | |
1053 | est_niter = expected_loop_iterations (loop); | |
1054 | determine_exit_conditions (loop, desc, factor, | |
1055 | &enter_main_cond, &exit_base, &exit_step, | |
1056 | &exit_cmp, &exit_bound); | |
1057 | ||
7cef6c97 | 1058 | /* Let us assume that the unrolled loop is quite likely to be entered. */ |
1059 | if (integer_nonzerop (enter_main_cond)) | |
1060 | prob_entry = REG_BR_PROB_BASE; | |
1061 | else | |
1062 | prob_entry = PROB_UNROLLED_LOOP_ENTERED * REG_BR_PROB_BASE / 100; | |
1063 | ||
1064 | /* The values for scales should keep profile consistent, and somewhat close | |
1065 | to correct. | |
1066 | ||
1067 | TODO: The current value of SCALE_REST makes it appear that the loop that | |
1068 | is created by splitting the remaining iterations of the unrolled loop is | |
1069 | executed the same number of times as the original loop, and with the same | |
1070 | frequencies, which is obviously wrong. This does not appear to cause | |
1071 | problems, so we do not bother with fixing it for now. To make the profile | |
1072 | correct, we would need to change the probability of the exit edge of the | |
1073 | loop, and recompute the distribution of frequencies in its body because | |
1074 | of this change (scale the frequencies of blocks before and after the exit | |
1075 | by appropriate factors). */ | |
1076 | scale_unrolled = prob_entry; | |
1077 | scale_rest = REG_BR_PROB_BASE; | |
1078 | ||
1079 | new_loop = loop_version (loop, enter_main_cond, NULL, | |
1080 | prob_entry, scale_unrolled, scale_rest, true); | |
b30560de | 1081 | gcc_assert (new_loop != NULL); |
1082 | update_ssa (TODO_update_ssa); | |
1083 | ||
f6ae6f2a | 1084 | /* Determine the probability of the exit edge of the unrolled loop. */ |
7cef6c97 | 1085 | new_est_niter = est_niter / factor; |
1086 | ||
1087 | /* Without profile feedback, loops for that we do not know a better estimate | |
1088 | are assumed to roll 10 times. When we unroll such loop, it appears to | |
1089 | roll too little, and it may even seem to be cold. To avoid this, we | |
1090 | ensure that the created loop appears to roll at least 5 times (but at | |
1091 | most as many times as before unrolling). */ | |
1092 | if (new_est_niter < 5) | |
1093 | { | |
1094 | if (est_niter < 5) | |
1095 | new_est_niter = est_niter; | |
1096 | else | |
1097 | new_est_niter = 5; | |
1098 | } | |
1099 | ||
611d2ac1 | 1100 | /* Prepare the cfg and update the phi nodes. Move the loop exit to the |
1101 | loop latch (and make its condition dummy, for the moment). */ | |
b30560de | 1102 | rest = loop_preheader_edge (new_loop)->src; |
1103 | precond_edge = single_pred_edge (rest); | |
88e6f696 | 1104 | split_edge (loop_latch_edge (loop)); |
b30560de | 1105 | exit_bb = single_pred (loop->latch); |
1106 | ||
611d2ac1 | 1107 | /* Since the exit edge will be removed, the frequency of all the blocks |
1108 | in the loop that are dominated by it must be scaled by | |
1109 | 1 / (1 - exit->probability). */ | |
1110 | scale_dominated_blocks_in_loop (loop, exit->src, | |
1111 | REG_BR_PROB_BASE, | |
1112 | REG_BR_PROB_BASE - exit->probability); | |
1113 | ||
75a70cf9 | 1114 | bsi = gsi_last_bb (exit_bb); |
1115 | exit_if = gimple_build_cond (EQ_EXPR, integer_zero_node, | |
1116 | integer_zero_node, | |
1117 | NULL_TREE, NULL_TREE); | |
63f88450 | 1118 | |
75a70cf9 | 1119 | gsi_insert_after (&bsi, exit_if, GSI_NEW_STMT); |
89c8b802 | 1120 | new_exit = make_edge (exit_bb, rest, EDGE_FALSE_VALUE | irr); |
dce58e66 | 1121 | rescan_loop_exit (new_exit, true, false); |
611d2ac1 | 1122 | |
1123 | /* Set the probability of new exit to the same of the old one. Fix | |
1124 | the frequency of the latch block, by scaling it back by | |
1125 | 1 - exit->probability. */ | |
1126 | new_exit->count = exit->count; | |
1127 | new_exit->probability = exit->probability; | |
b30560de | 1128 | new_nonexit = single_pred_edge (loop->latch); |
611d2ac1 | 1129 | new_nonexit->probability = REG_BR_PROB_BASE - exit->probability; |
b30560de | 1130 | new_nonexit->flags = EDGE_TRUE_VALUE; |
611d2ac1 | 1131 | new_nonexit->count -= exit->count; |
1132 | if (new_nonexit->count < 0) | |
1133 | new_nonexit->count = 0; | |
1134 | scale_bbs_frequencies_int (&loop->latch, 1, new_nonexit->probability, | |
1135 | REG_BR_PROB_BASE); | |
b30560de | 1136 | |
1137 | old_entry = loop_preheader_edge (loop); | |
1138 | new_entry = loop_preheader_edge (new_loop); | |
1139 | old_latch = loop_latch_edge (loop); | |
75a70cf9 | 1140 | for (psi_old_loop = gsi_start_phis (loop->header), |
1141 | psi_new_loop = gsi_start_phis (new_loop->header); | |
1142 | !gsi_end_p (psi_old_loop); | |
1143 | gsi_next (&psi_old_loop), gsi_next (&psi_new_loop)) | |
b30560de | 1144 | { |
75a70cf9 | 1145 | phi_old_loop = gsi_stmt (psi_old_loop); |
1146 | phi_new_loop = gsi_stmt (psi_new_loop); | |
1147 | ||
b30560de | 1148 | init = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_entry); |
1149 | op = PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop, new_entry); | |
1150 | gcc_assert (operand_equal_for_phi_arg_p (init, USE_FROM_PTR (op))); | |
1151 | next = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_latch); | |
1152 | ||
1153 | /* Prefer using original variable as a base for the new ssa name. | |
1154 | This is necessary for virtual ops, and useful in order to avoid | |
1155 | losing debug info for real ops. */ | |
b34a77f7 | 1156 | if (TREE_CODE (next) == SSA_NAME |
1157 | && useless_type_conversion_p (TREE_TYPE (next), | |
1158 | TREE_TYPE (init))) | |
ec11736b | 1159 | new_init = copy_ssa_name (next, NULL); |
b34a77f7 | 1160 | else if (TREE_CODE (init) == SSA_NAME |
1161 | && useless_type_conversion_p (TREE_TYPE (init), | |
1162 | TREE_TYPE (next))) | |
ec11736b | 1163 | new_init = copy_ssa_name (init, NULL); |
b34a77f7 | 1164 | else if (useless_type_conversion_p (TREE_TYPE (next), TREE_TYPE (init))) |
ec11736b | 1165 | new_init = make_temp_ssa_name (TREE_TYPE (next), NULL, "unrinittmp"); |
b30560de | 1166 | else |
ec11736b | 1167 | new_init = make_temp_ssa_name (TREE_TYPE (init), NULL, "unrinittmp"); |
b30560de | 1168 | |
b30560de | 1169 | phi_rest = create_phi_node (new_init, rest); |
b30560de | 1170 | |
60d535d2 | 1171 | add_phi_arg (phi_rest, init, precond_edge, UNKNOWN_LOCATION); |
1172 | add_phi_arg (phi_rest, next, new_exit, UNKNOWN_LOCATION); | |
b30560de | 1173 | SET_USE (op, new_init); |
1174 | } | |
1175 | ||
611d2ac1 | 1176 | remove_path (exit); |
1177 | ||
f6ae6f2a | 1178 | /* Transform the loop. */ |
1179 | if (transform) | |
1180 | (*transform) (loop, data); | |
1181 | ||
611d2ac1 | 1182 | /* Unroll the loop and remove the exits in all iterations except for the |
1183 | last one. */ | |
f6ae6f2a | 1184 | wont_exit = sbitmap_alloc (factor); |
53c5d9d4 | 1185 | bitmap_ones (wont_exit); |
08b7917c | 1186 | bitmap_clear_bit (wont_exit, factor - 1); |
611d2ac1 | 1187 | |
75a70cf9 | 1188 | ok = gimple_duplicate_loop_to_header_edge |
f6ae6f2a | 1189 | (loop, loop_latch_edge (loop), factor - 1, |
611d2ac1 | 1190 | wont_exit, new_exit, &to_remove, DLTHE_FLAG_UPDATE_FREQ); |
f6ae6f2a | 1191 | free (wont_exit); |
1192 | gcc_assert (ok); | |
611d2ac1 | 1193 | |
f1f41a6c | 1194 | FOR_EACH_VEC_ELT (to_remove, i, e) |
611d2ac1 | 1195 | { |
1196 | ok = remove_path (e); | |
1197 | gcc_assert (ok); | |
1198 | } | |
f6ae6f2a | 1199 | update_ssa (TODO_update_ssa); |
1200 | ||
1201 | /* Ensure that the frequencies in the loop match the new estimated | |
1202 | number of iterations, and change the probability of the new | |
1203 | exit edge. */ | |
1204 | freq_h = loop->header->frequency; | |
1205 | freq_e = EDGE_FREQUENCY (loop_preheader_edge (loop)); | |
1206 | if (freq_h != 0) | |
1207 | scale_loop_frequencies (loop, freq_e * (new_est_niter + 1), freq_h); | |
1208 | ||
1209 | exit_bb = single_pred (loop->latch); | |
1210 | new_exit = find_edge (exit_bb, rest); | |
1211 | new_exit->count = loop_preheader_edge (loop)->count; | |
1212 | new_exit->probability = REG_BR_PROB_BASE / (new_est_niter + 1); | |
1213 | ||
1214 | rest->count += new_exit->count; | |
1215 | rest->frequency += EDGE_FREQUENCY (new_exit); | |
1216 | ||
1217 | new_nonexit = single_pred_edge (loop->latch); | |
611d2ac1 | 1218 | prob = new_nonexit->probability; |
f6ae6f2a | 1219 | new_nonexit->probability = REG_BR_PROB_BASE - new_exit->probability; |
611d2ac1 | 1220 | new_nonexit->count = exit_bb->count - new_exit->count; |
1221 | if (new_nonexit->count < 0) | |
1222 | new_nonexit->count = 0; | |
be429d54 | 1223 | if (prob > 0) |
1224 | scale_bbs_frequencies_int (&loop->latch, 1, new_nonexit->probability, | |
1225 | prob); | |
f6ae6f2a | 1226 | |
b30560de | 1227 | /* Finally create the new counter for number of iterations and add the new |
1228 | exit instruction. */ | |
320e3d05 | 1229 | bsi = gsi_last_nondebug_bb (exit_bb); |
75a70cf9 | 1230 | exit_if = gsi_stmt (bsi); |
b30560de | 1231 | create_iv (exit_base, exit_step, NULL_TREE, loop, |
f6ae6f2a | 1232 | &bsi, false, &ctr_before, &ctr_after); |
75a70cf9 | 1233 | gimple_cond_set_code (exit_if, exit_cmp); |
1234 | gimple_cond_set_lhs (exit_if, ctr_after); | |
1235 | gimple_cond_set_rhs (exit_if, exit_bound); | |
f6ae6f2a | 1236 | update_stmt (exit_if); |
b30560de | 1237 | |
56743459 | 1238 | #ifdef ENABLE_CHECKING |
b30560de | 1239 | verify_flow_info (); |
7194de72 | 1240 | verify_loop_structure (); |
ca77c6ec | 1241 | verify_loop_closed_ssa (true); |
56743459 | 1242 | #endif |
b30560de | 1243 | } |
f6ae6f2a | 1244 | |
1245 | /* Wrapper over tree_transform_and_unroll_loop for case we do not | |
1246 | want to transform the loop before unrolling. The meaning | |
1247 | of the arguments is the same as for tree_transform_and_unroll_loop. */ | |
1248 | ||
1249 | void | |
1250 | tree_unroll_loop (struct loop *loop, unsigned factor, | |
1251 | edge exit, struct tree_niter_desc *desc) | |
1252 | { | |
1253 | tree_transform_and_unroll_loop (loop, factor, exit, desc, | |
1254 | NULL, NULL); | |
1255 | } | |
5fa90eea | 1256 | |
1257 | /* Rewrite the phi node at position PSI in function of the main | |
1258 | induction variable MAIN_IV and insert the generated code at GSI. */ | |
1259 | ||
1260 | static void | |
1261 | rewrite_phi_with_iv (loop_p loop, | |
1262 | gimple_stmt_iterator *psi, | |
1263 | gimple_stmt_iterator *gsi, | |
1264 | tree main_iv) | |
1265 | { | |
1266 | affine_iv iv; | |
1267 | gimple stmt, phi = gsi_stmt (*psi); | |
1268 | tree atype, mtype, val, res = PHI_RESULT (phi); | |
1269 | ||
7c782c9b | 1270 | if (virtual_operand_p (res) || res == main_iv) |
5fa90eea | 1271 | { |
1272 | gsi_next (psi); | |
1273 | return; | |
1274 | } | |
1275 | ||
1276 | if (!simple_iv (loop, loop, res, &iv, true)) | |
1277 | { | |
1278 | gsi_next (psi); | |
1279 | return; | |
1280 | } | |
1281 | ||
1282 | remove_phi_node (psi, false); | |
1283 | ||
1284 | atype = TREE_TYPE (res); | |
1285 | mtype = POINTER_TYPE_P (atype) ? sizetype : atype; | |
1286 | val = fold_build2 (MULT_EXPR, mtype, unshare_expr (iv.step), | |
1287 | fold_convert (mtype, main_iv)); | |
1288 | val = fold_build2 (POINTER_TYPE_P (atype) | |
1289 | ? POINTER_PLUS_EXPR : PLUS_EXPR, | |
1290 | atype, unshare_expr (iv.base), val); | |
1291 | val = force_gimple_operand_gsi (gsi, val, false, NULL_TREE, true, | |
1292 | GSI_SAME_STMT); | |
1293 | stmt = gimple_build_assign (res, val); | |
1294 | gsi_insert_before (gsi, stmt, GSI_SAME_STMT); | |
5fa90eea | 1295 | } |
1296 | ||
1297 | /* Rewrite all the phi nodes of LOOP in function of the main induction | |
1298 | variable MAIN_IV. */ | |
1299 | ||
1300 | static void | |
1301 | rewrite_all_phi_nodes_with_iv (loop_p loop, tree main_iv) | |
1302 | { | |
1303 | unsigned i; | |
1304 | basic_block *bbs = get_loop_body_in_dom_order (loop); | |
1305 | gimple_stmt_iterator psi; | |
1306 | ||
1307 | for (i = 0; i < loop->num_nodes; i++) | |
1308 | { | |
1309 | basic_block bb = bbs[i]; | |
1310 | gimple_stmt_iterator gsi = gsi_after_labels (bb); | |
1311 | ||
1312 | if (bb->loop_father != loop) | |
1313 | continue; | |
1314 | ||
1315 | for (psi = gsi_start_phis (bb); !gsi_end_p (psi); ) | |
1316 | rewrite_phi_with_iv (loop, &psi, &gsi, main_iv); | |
1317 | } | |
1318 | ||
1319 | free (bbs); | |
1320 | } | |
1321 | ||
1322 | /* Bases all the induction variables in LOOP on a single induction | |
1323 | variable (unsigned with base 0 and step 1), whose final value is | |
1324 | compared with *NIT. When the IV type precision has to be larger | |
1325 | than *NIT type precision, *NIT is converted to the larger type, the | |
1326 | conversion code is inserted before the loop, and *NIT is updated to | |
0207206d | 1327 | the new definition. When BUMP_IN_LATCH is true, the induction |
1328 | variable is incremented in the loop latch, otherwise it is | |
1329 | incremented in the loop header. Return the induction variable that | |
1330 | was created. */ | |
5fa90eea | 1331 | |
1332 | tree | |
0207206d | 1333 | canonicalize_loop_ivs (struct loop *loop, tree *nit, bool bump_in_latch) |
5fa90eea | 1334 | { |
1335 | unsigned precision = TYPE_PRECISION (TREE_TYPE (*nit)); | |
1336 | unsigned original_precision = precision; | |
1337 | tree type, var_before; | |
1338 | gimple_stmt_iterator gsi, psi; | |
1339 | gimple stmt; | |
1340 | edge exit = single_dom_exit (loop); | |
1341 | gimple_seq stmts; | |
38a66497 | 1342 | enum machine_mode mode; |
1343 | bool unsigned_p = false; | |
5fa90eea | 1344 | |
1345 | for (psi = gsi_start_phis (loop->header); | |
1346 | !gsi_end_p (psi); gsi_next (&psi)) | |
1347 | { | |
1348 | gimple phi = gsi_stmt (psi); | |
1349 | tree res = PHI_RESULT (phi); | |
38a66497 | 1350 | bool uns; |
5fa90eea | 1351 | |
38a66497 | 1352 | type = TREE_TYPE (res); |
7c782c9b | 1353 | if (virtual_operand_p (res) |
38a66497 | 1354 | || (!INTEGRAL_TYPE_P (type) |
1355 | && !POINTER_TYPE_P (type)) | |
1356 | || TYPE_PRECISION (type) < precision) | |
1357 | continue; | |
1358 | ||
1359 | uns = POINTER_TYPE_P (type) | TYPE_UNSIGNED (type); | |
1360 | ||
1361 | if (TYPE_PRECISION (type) > precision) | |
1362 | unsigned_p = uns; | |
1363 | else | |
1364 | unsigned_p |= uns; | |
1365 | ||
1366 | precision = TYPE_PRECISION (type); | |
5fa90eea | 1367 | } |
1368 | ||
38a66497 | 1369 | mode = smallest_mode_for_size (precision, MODE_INT); |
1370 | precision = GET_MODE_PRECISION (mode); | |
1371 | type = build_nonstandard_integer_type (precision, unsigned_p); | |
5fa90eea | 1372 | |
1373 | if (original_precision != precision) | |
1374 | { | |
1375 | *nit = fold_convert (type, *nit); | |
1376 | *nit = force_gimple_operand (*nit, &stmts, true, NULL_TREE); | |
1377 | if (stmts) | |
1378 | gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); | |
1379 | } | |
1380 | ||
149c96e8 | 1381 | if (bump_in_latch) |
1382 | gsi = gsi_last_bb (loop->latch); | |
1383 | else | |
1384 | gsi = gsi_last_nondebug_bb (loop->header); | |
5fa90eea | 1385 | create_iv (build_int_cst_type (type, 0), build_int_cst (type, 1), NULL_TREE, |
0207206d | 1386 | loop, &gsi, bump_in_latch, &var_before, NULL); |
5fa90eea | 1387 | |
1388 | rewrite_all_phi_nodes_with_iv (loop, var_before); | |
1389 | ||
1390 | stmt = last_stmt (exit->src); | |
1391 | /* Make the loop exit if the control condition is not satisfied. */ | |
1392 | if (exit->flags & EDGE_TRUE_VALUE) | |
1393 | { | |
1394 | edge te, fe; | |
1395 | ||
1396 | extract_true_false_edges_from_block (exit->src, &te, &fe); | |
1397 | te->flags = EDGE_FALSE_VALUE; | |
1398 | fe->flags = EDGE_TRUE_VALUE; | |
1399 | } | |
1400 | gimple_cond_set_code (stmt, LT_EXPR); | |
1401 | gimple_cond_set_lhs (stmt, var_before); | |
1402 | gimple_cond_set_rhs (stmt, *nit); | |
1403 | update_stmt (stmt); | |
1404 | ||
1405 | return var_before; | |
1406 | } |