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[official-gcc.git] / gcc / tree-ssa-loop-manip.c
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1 /* High-level loop manipulation functions.
2 Copyright (C) 2004-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
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
8 Free Software Foundation; either version 3, or (at your option) any
9 later version.
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.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "tm.h"
24 #include "hash-set.h"
25 #include "machmode.h"
26 #include "vec.h"
27 #include "double-int.h"
28 #include "input.h"
29 #include "alias.h"
30 #include "symtab.h"
31 #include "wide-int.h"
32 #include "inchash.h"
33 #include "tree.h"
34 #include "fold-const.h"
35 #include "tm_p.h"
36 #include "predict.h"
37 #include "hard-reg-set.h"
38 #include "input.h"
39 #include "function.h"
40 #include "dominance.h"
41 #include "cfg.h"
42 #include "cfganal.h"
43 #include "basic-block.h"
44 #include "tree-ssa-alias.h"
45 #include "internal-fn.h"
46 #include "gimple-expr.h"
47 #include "is-a.h"
48 #include "gimple.h"
49 #include "gimplify.h"
50 #include "gimple-iterator.h"
51 #include "gimplify-me.h"
52 #include "gimple-ssa.h"
53 #include "tree-cfg.h"
54 #include "tree-phinodes.h"
55 #include "ssa-iterators.h"
56 #include "stringpool.h"
57 #include "tree-ssanames.h"
58 #include "tree-ssa-loop-ivopts.h"
59 #include "tree-ssa-loop-manip.h"
60 #include "tree-ssa-loop-niter.h"
61 #include "tree-ssa-loop.h"
62 #include "tree-into-ssa.h"
63 #include "tree-ssa.h"
64 #include "dumpfile.h"
65 #include "gimple-pretty-print.h"
66 #include "cfgloop.h"
67 #include "tree-pass.h" /* ??? for TODO_update_ssa but this isn't a pass. */
68 #include "tree-scalar-evolution.h"
69 #include "params.h"
70 #include "tree-inline.h"
71 #include "langhooks.h"
73 /* All bitmaps for rewriting into loop-closed SSA go on this obstack,
74 so that we can free them all at once. */
75 static bitmap_obstack loop_renamer_obstack;
77 /* Creates an induction variable with value BASE + STEP * iteration in LOOP.
78 It is expected that neither BASE nor STEP are shared with other expressions
79 (unless the sharing rules allow this). Use VAR as a base var_decl for it
80 (if NULL, a new temporary will be created). The increment will occur at
81 INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and
82 AFTER can be computed using standard_iv_increment_position. The ssa versions
83 of the variable before and after increment will be stored in VAR_BEFORE and
84 VAR_AFTER (unless they are NULL). */
86 void
87 create_iv (tree base, tree step, tree var, struct loop *loop,
88 gimple_stmt_iterator *incr_pos, bool after,
89 tree *var_before, tree *var_after)
91 gassign *stmt;
92 gphi *phi;
93 tree initial, step1;
94 gimple_seq stmts;
95 tree vb, va;
96 enum tree_code incr_op = PLUS_EXPR;
97 edge pe = loop_preheader_edge (loop);
99 if (var != NULL_TREE)
101 vb = make_ssa_name (var);
102 va = make_ssa_name (var);
104 else
106 vb = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp");
107 va = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp");
109 if (var_before)
110 *var_before = vb;
111 if (var_after)
112 *var_after = va;
114 /* For easier readability of the created code, produce MINUS_EXPRs
115 when suitable. */
116 if (TREE_CODE (step) == INTEGER_CST)
118 if (TYPE_UNSIGNED (TREE_TYPE (step)))
120 step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
121 if (tree_int_cst_lt (step1, step))
123 incr_op = MINUS_EXPR;
124 step = step1;
127 else
129 bool ovf;
131 if (!tree_expr_nonnegative_warnv_p (step, &ovf)
132 && may_negate_without_overflow_p (step))
134 incr_op = MINUS_EXPR;
135 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
139 if (POINTER_TYPE_P (TREE_TYPE (base)))
141 if (TREE_CODE (base) == ADDR_EXPR)
142 mark_addressable (TREE_OPERAND (base, 0));
143 step = convert_to_ptrofftype (step);
144 if (incr_op == MINUS_EXPR)
145 step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
146 incr_op = POINTER_PLUS_EXPR;
148 /* Gimplify the step if necessary. We put the computations in front of the
149 loop (i.e. the step should be loop invariant). */
150 step = force_gimple_operand (step, &stmts, true, NULL_TREE);
151 if (stmts)
152 gsi_insert_seq_on_edge_immediate (pe, stmts);
154 stmt = gimple_build_assign (va, incr_op, vb, step);
155 if (after)
156 gsi_insert_after (incr_pos, stmt, GSI_NEW_STMT);
157 else
158 gsi_insert_before (incr_pos, stmt, GSI_NEW_STMT);
160 initial = force_gimple_operand (base, &stmts, true, var);
161 if (stmts)
162 gsi_insert_seq_on_edge_immediate (pe, stmts);
164 phi = create_phi_node (vb, loop->header);
165 add_phi_arg (phi, initial, loop_preheader_edge (loop), UNKNOWN_LOCATION);
166 add_phi_arg (phi, va, loop_latch_edge (loop), UNKNOWN_LOCATION);
169 /* Return the innermost superloop LOOP of USE_LOOP that is a superloop of
170 both DEF_LOOP and USE_LOOP. */
172 static inline struct loop *
173 find_sibling_superloop (struct loop *use_loop, struct loop *def_loop)
175 unsigned ud = loop_depth (use_loop);
176 unsigned dd = loop_depth (def_loop);
177 gcc_assert (ud > 0 && dd > 0);
178 if (ud > dd)
179 use_loop = superloop_at_depth (use_loop, dd);
180 if (ud < dd)
181 def_loop = superloop_at_depth (def_loop, ud);
182 while (loop_outer (use_loop) != loop_outer (def_loop))
184 use_loop = loop_outer (use_loop);
185 def_loop = loop_outer (def_loop);
186 gcc_assert (use_loop && def_loop);
188 return use_loop;
191 /* DEF_BB is a basic block containing a DEF that needs rewriting into
192 loop-closed SSA form. USE_BLOCKS is the set of basic blocks containing
193 uses of DEF that "escape" from the loop containing DEF_BB (i.e. blocks in
194 USE_BLOCKS are dominated by DEF_BB but not in the loop father of DEF_B).
195 ALL_EXITS[I] is the set of all basic blocks that exit loop I.
197 Compute the subset of LOOP_EXITS that exit the loop containing DEF_BB
198 or one of its loop fathers, in which DEF is live. This set is returned
199 in the bitmap LIVE_EXITS.
201 Instead of computing the complete livein set of the def, we use the loop
202 nesting tree as a form of poor man's structure analysis. This greatly
203 speeds up the analysis, which is important because this function may be
204 called on all SSA names that need rewriting, one at a time. */
206 static void
207 compute_live_loop_exits (bitmap live_exits, bitmap use_blocks,
208 bitmap *loop_exits, basic_block def_bb)
210 unsigned i;
211 bitmap_iterator bi;
212 struct loop *def_loop = def_bb->loop_father;
213 unsigned def_loop_depth = loop_depth (def_loop);
214 bitmap def_loop_exits;
216 /* Normally the work list size is bounded by the number of basic
217 blocks in the largest loop. We don't know this number, but we
218 can be fairly sure that it will be relatively small. */
219 auto_vec<basic_block> worklist (MAX (8, n_basic_blocks_for_fn (cfun) / 128));
221 EXECUTE_IF_SET_IN_BITMAP (use_blocks, 0, i, bi)
223 basic_block use_bb = BASIC_BLOCK_FOR_FN (cfun, i);
224 struct loop *use_loop = use_bb->loop_father;
225 gcc_checking_assert (def_loop != use_loop
226 && ! flow_loop_nested_p (def_loop, use_loop));
227 if (! flow_loop_nested_p (use_loop, def_loop))
228 use_bb = find_sibling_superloop (use_loop, def_loop)->header;
229 if (bitmap_set_bit (live_exits, use_bb->index))
230 worklist.safe_push (use_bb);
233 /* Iterate until the worklist is empty. */
234 while (! worklist.is_empty ())
236 edge e;
237 edge_iterator ei;
239 /* Pull a block off the worklist. */
240 basic_block bb = worklist.pop ();
242 /* Make sure we have at least enough room in the work list
243 for all predecessors of this block. */
244 worklist.reserve (EDGE_COUNT (bb->preds));
246 /* For each predecessor block. */
247 FOR_EACH_EDGE (e, ei, bb->preds)
249 basic_block pred = e->src;
250 struct loop *pred_loop = pred->loop_father;
251 unsigned pred_loop_depth = loop_depth (pred_loop);
252 bool pred_visited;
254 /* We should have met DEF_BB along the way. */
255 gcc_assert (pred != ENTRY_BLOCK_PTR_FOR_FN (cfun));
257 if (pred_loop_depth >= def_loop_depth)
259 if (pred_loop_depth > def_loop_depth)
260 pred_loop = superloop_at_depth (pred_loop, def_loop_depth);
261 /* If we've reached DEF_LOOP, our train ends here. */
262 if (pred_loop == def_loop)
263 continue;
265 else if (! flow_loop_nested_p (pred_loop, def_loop))
266 pred = find_sibling_superloop (pred_loop, def_loop)->header;
268 /* Add PRED to the LIVEIN set. PRED_VISITED is true if
269 we had already added PRED to LIVEIN before. */
270 pred_visited = !bitmap_set_bit (live_exits, pred->index);
272 /* If we have visited PRED before, don't add it to the worklist.
273 If BB dominates PRED, then we're probably looking at a loop.
274 We're only interested in looking up in the dominance tree
275 because DEF_BB dominates all the uses. */
276 if (pred_visited || dominated_by_p (CDI_DOMINATORS, pred, bb))
277 continue;
279 worklist.quick_push (pred);
283 def_loop_exits = BITMAP_ALLOC (&loop_renamer_obstack);
284 for (struct loop *loop = def_loop;
285 loop != current_loops->tree_root;
286 loop = loop_outer (loop))
287 bitmap_ior_into (def_loop_exits, loop_exits[loop->num]);
288 bitmap_and_into (live_exits, def_loop_exits);
289 BITMAP_FREE (def_loop_exits);
292 /* Add a loop-closing PHI for VAR in basic block EXIT. */
294 static void
295 add_exit_phi (basic_block exit, tree var)
297 gphi *phi;
298 edge e;
299 edge_iterator ei;
301 #ifdef ENABLE_CHECKING
302 /* Check that at least one of the edges entering the EXIT block exits
303 the loop, or a superloop of that loop, that VAR is defined in. */
304 gimple def_stmt = SSA_NAME_DEF_STMT (var);
305 basic_block def_bb = gimple_bb (def_stmt);
306 FOR_EACH_EDGE (e, ei, exit->preds)
308 struct loop *aloop = find_common_loop (def_bb->loop_father,
309 e->src->loop_father);
310 if (!flow_bb_inside_loop_p (aloop, e->dest))
311 break;
314 gcc_checking_assert (e);
315 #endif
317 phi = create_phi_node (NULL_TREE, exit);
318 create_new_def_for (var, phi, gimple_phi_result_ptr (phi));
319 FOR_EACH_EDGE (e, ei, exit->preds)
320 add_phi_arg (phi, var, e, UNKNOWN_LOCATION);
322 if (dump_file && (dump_flags & TDF_DETAILS))
324 fprintf (dump_file, ";; Created LCSSA PHI: ");
325 print_gimple_stmt (dump_file, phi, 0, dump_flags);
329 /* Add exit phis for VAR that is used in LIVEIN.
330 Exits of the loops are stored in LOOP_EXITS. */
332 static void
333 add_exit_phis_var (tree var, bitmap use_blocks, bitmap *loop_exits)
335 unsigned index;
336 bitmap_iterator bi;
337 basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (var));
338 bitmap live_exits = BITMAP_ALLOC (&loop_renamer_obstack);
340 gcc_checking_assert (! bitmap_bit_p (use_blocks, def_bb->index));
342 compute_live_loop_exits (live_exits, use_blocks, loop_exits, def_bb);
344 EXECUTE_IF_SET_IN_BITMAP (live_exits, 0, index, bi)
346 add_exit_phi (BASIC_BLOCK_FOR_FN (cfun, index), var);
349 BITMAP_FREE (live_exits);
352 /* Add exit phis for the names marked in NAMES_TO_RENAME.
353 Exits of the loops are stored in EXITS. Sets of blocks where the ssa
354 names are used are stored in USE_BLOCKS. */
356 static void
357 add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap *loop_exits)
359 unsigned i;
360 bitmap_iterator bi;
362 EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i, bi)
364 add_exit_phis_var (ssa_name (i), use_blocks[i], loop_exits);
368 /* Fill the array of bitmaps LOOP_EXITS with all loop exit edge targets. */
370 static void
371 get_loops_exits (bitmap *loop_exits)
373 struct loop *loop;
374 unsigned j;
375 edge e;
377 FOR_EACH_LOOP (loop, 0)
379 vec<edge> exit_edges = get_loop_exit_edges (loop);
380 loop_exits[loop->num] = BITMAP_ALLOC (&loop_renamer_obstack);
381 FOR_EACH_VEC_ELT (exit_edges, j, e)
382 bitmap_set_bit (loop_exits[loop->num], e->dest->index);
383 exit_edges.release ();
387 /* For USE in BB, if it is used outside of the loop it is defined in,
388 mark it for rewrite. Record basic block BB where it is used
389 to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap. */
391 static void
392 find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks,
393 bitmap need_phis)
395 unsigned ver;
396 basic_block def_bb;
397 struct loop *def_loop;
399 if (TREE_CODE (use) != SSA_NAME)
400 return;
402 ver = SSA_NAME_VERSION (use);
403 def_bb = gimple_bb (SSA_NAME_DEF_STMT (use));
404 if (!def_bb)
405 return;
406 def_loop = def_bb->loop_father;
408 /* If the definition is not inside a loop, it is not interesting. */
409 if (!loop_outer (def_loop))
410 return;
412 /* If the use is not outside of the loop it is defined in, it is not
413 interesting. */
414 if (flow_bb_inside_loop_p (def_loop, bb))
415 return;
417 /* If we're seeing VER for the first time, we still have to allocate
418 a bitmap for its uses. */
419 if (bitmap_set_bit (need_phis, ver))
420 use_blocks[ver] = BITMAP_ALLOC (&loop_renamer_obstack);
421 bitmap_set_bit (use_blocks[ver], bb->index);
424 /* For uses in STMT, mark names that are used outside of the loop they are
425 defined to rewrite. Record the set of blocks in that the ssa
426 names are defined to USE_BLOCKS and the ssa names themselves to
427 NEED_PHIS. */
429 static void
430 find_uses_to_rename_stmt (gimple stmt, bitmap *use_blocks, bitmap need_phis)
432 ssa_op_iter iter;
433 tree var;
434 basic_block bb = gimple_bb (stmt);
436 if (is_gimple_debug (stmt))
437 return;
439 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
440 find_uses_to_rename_use (bb, var, use_blocks, need_phis);
443 /* Marks names that are used in BB and outside of the loop they are
444 defined in for rewrite. Records the set of blocks in that the ssa
445 names are defined to USE_BLOCKS. Record the SSA names that will
446 need exit PHIs in NEED_PHIS. */
448 static void
449 find_uses_to_rename_bb (basic_block bb, bitmap *use_blocks, bitmap need_phis)
451 edge e;
452 edge_iterator ei;
454 FOR_EACH_EDGE (e, ei, bb->succs)
455 for (gphi_iterator bsi = gsi_start_phis (e->dest); !gsi_end_p (bsi);
456 gsi_next (&bsi))
458 gphi *phi = bsi.phi ();
459 if (! virtual_operand_p (gimple_phi_result (phi)))
460 find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e),
461 use_blocks, need_phis);
464 for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (bsi);
465 gsi_next (&bsi))
466 find_uses_to_rename_stmt (gsi_stmt (bsi), use_blocks, need_phis);
469 /* Marks names that are used outside of the loop they are defined in
470 for rewrite. Records the set of blocks in that the ssa
471 names are defined to USE_BLOCKS. If CHANGED_BBS is not NULL,
472 scan only blocks in this set. */
474 static void
475 find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis)
477 basic_block bb;
478 unsigned index;
479 bitmap_iterator bi;
481 if (changed_bbs)
482 EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi)
483 find_uses_to_rename_bb (BASIC_BLOCK_FOR_FN (cfun, index), use_blocks, need_phis);
484 else
485 FOR_EACH_BB_FN (bb, cfun)
486 find_uses_to_rename_bb (bb, use_blocks, need_phis);
489 /* Rewrites the program into a loop closed ssa form -- i.e. inserts extra
490 phi nodes to ensure that no variable is used outside the loop it is
491 defined in.
493 This strengthening of the basic ssa form has several advantages:
495 1) Updating it during unrolling/peeling/versioning is trivial, since
496 we do not need to care about the uses outside of the loop.
497 The same applies to virtual operands which are also rewritten into
498 loop closed SSA form. Note that virtual operands are always live
499 until function exit.
500 2) The behavior of all uses of an induction variable is the same.
501 Without this, you need to distinguish the case when the variable
502 is used outside of the loop it is defined in, for example
504 for (i = 0; i < 100; i++)
506 for (j = 0; j < 100; j++)
508 k = i + j;
509 use1 (k);
511 use2 (k);
514 Looking from the outer loop with the normal SSA form, the first use of k
515 is not well-behaved, while the second one is an induction variable with
516 base 99 and step 1.
518 If CHANGED_BBS is not NULL, we look for uses outside loops only in
519 the basic blocks in this set.
521 UPDATE_FLAG is used in the call to update_ssa. See
522 TODO_update_ssa* for documentation. */
524 void
525 rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag)
527 bitmap *use_blocks;
528 bitmap names_to_rename;
530 loops_state_set (LOOP_CLOSED_SSA);
531 if (number_of_loops (cfun) <= 1)
532 return;
534 /* If the pass has caused the SSA form to be out-of-date, update it
535 now. */
536 update_ssa (update_flag);
538 bitmap_obstack_initialize (&loop_renamer_obstack);
540 names_to_rename = BITMAP_ALLOC (&loop_renamer_obstack);
542 /* Uses of names to rename. We don't have to initialize this array,
543 because we know that we will only have entries for the SSA names
544 in NAMES_TO_RENAME. */
545 use_blocks = XNEWVEC (bitmap, num_ssa_names);
547 /* Find the uses outside loops. */
548 find_uses_to_rename (changed_bbs, use_blocks, names_to_rename);
550 if (!bitmap_empty_p (names_to_rename))
552 /* An array of bitmaps where LOOP_EXITS[I] is the set of basic blocks
553 that are the destination of an edge exiting loop number I. */
554 bitmap *loop_exits = XNEWVEC (bitmap, number_of_loops (cfun));
555 get_loops_exits (loop_exits);
557 /* Add the PHI nodes on exits of the loops for the names we need to
558 rewrite. */
559 add_exit_phis (names_to_rename, use_blocks, loop_exits);
561 free (loop_exits);
563 /* Fix up all the names found to be used outside their original
564 loops. */
565 update_ssa (TODO_update_ssa);
568 bitmap_obstack_release (&loop_renamer_obstack);
569 free (use_blocks);
572 /* Check invariants of the loop closed ssa form for the USE in BB. */
574 static void
575 check_loop_closed_ssa_use (basic_block bb, tree use)
577 gimple def;
578 basic_block def_bb;
580 if (TREE_CODE (use) != SSA_NAME || virtual_operand_p (use))
581 return;
583 def = SSA_NAME_DEF_STMT (use);
584 def_bb = gimple_bb (def);
585 gcc_assert (!def_bb
586 || flow_bb_inside_loop_p (def_bb->loop_father, bb));
589 /* Checks invariants of loop closed ssa form in statement STMT in BB. */
591 static void
592 check_loop_closed_ssa_stmt (basic_block bb, gimple stmt)
594 ssa_op_iter iter;
595 tree var;
597 if (is_gimple_debug (stmt))
598 return;
600 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
601 check_loop_closed_ssa_use (bb, var);
604 /* Checks that invariants of the loop closed ssa form are preserved.
605 Call verify_ssa when VERIFY_SSA_P is true. */
607 DEBUG_FUNCTION void
608 verify_loop_closed_ssa (bool verify_ssa_p)
610 basic_block bb;
611 edge e;
612 edge_iterator ei;
614 if (number_of_loops (cfun) <= 1)
615 return;
617 if (verify_ssa_p)
618 verify_ssa (false, true);
620 timevar_push (TV_VERIFY_LOOP_CLOSED);
622 FOR_EACH_BB_FN (bb, cfun)
624 for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (bsi);
625 gsi_next (&bsi))
627 gphi *phi = bsi.phi ();
628 FOR_EACH_EDGE (e, ei, bb->preds)
629 check_loop_closed_ssa_use (e->src,
630 PHI_ARG_DEF_FROM_EDGE (phi, e));
633 for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (bsi);
634 gsi_next (&bsi))
635 check_loop_closed_ssa_stmt (bb, gsi_stmt (bsi));
638 timevar_pop (TV_VERIFY_LOOP_CLOSED);
641 /* Split loop exit edge EXIT. The things are a bit complicated by a need to
642 preserve the loop closed ssa form. The newly created block is returned. */
644 basic_block
645 split_loop_exit_edge (edge exit)
647 basic_block dest = exit->dest;
648 basic_block bb = split_edge (exit);
649 gphi *phi, *new_phi;
650 tree new_name, name;
651 use_operand_p op_p;
652 gphi_iterator psi;
653 source_location locus;
655 for (psi = gsi_start_phis (dest); !gsi_end_p (psi); gsi_next (&psi))
657 phi = psi.phi ();
658 op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb));
659 locus = gimple_phi_arg_location_from_edge (phi, single_succ_edge (bb));
661 name = USE_FROM_PTR (op_p);
663 /* If the argument of the PHI node is a constant, we do not need
664 to keep it inside loop. */
665 if (TREE_CODE (name) != SSA_NAME)
666 continue;
668 /* Otherwise create an auxiliary phi node that will copy the value
669 of the SSA name out of the loop. */
670 new_name = duplicate_ssa_name (name, NULL);
671 new_phi = create_phi_node (new_name, bb);
672 add_phi_arg (new_phi, name, exit, locus);
673 SET_USE (op_p, new_name);
676 return bb;
679 /* Returns the basic block in that statements should be emitted for induction
680 variables incremented at the end of the LOOP. */
682 basic_block
683 ip_end_pos (struct loop *loop)
685 return loop->latch;
688 /* Returns the basic block in that statements should be emitted for induction
689 variables incremented just before exit condition of a LOOP. */
691 basic_block
692 ip_normal_pos (struct loop *loop)
694 gimple last;
695 basic_block bb;
696 edge exit;
698 if (!single_pred_p (loop->latch))
699 return NULL;
701 bb = single_pred (loop->latch);
702 last = last_stmt (bb);
703 if (!last
704 || gimple_code (last) != GIMPLE_COND)
705 return NULL;
707 exit = EDGE_SUCC (bb, 0);
708 if (exit->dest == loop->latch)
709 exit = EDGE_SUCC (bb, 1);
711 if (flow_bb_inside_loop_p (loop, exit->dest))
712 return NULL;
714 return bb;
717 /* Stores the standard position for induction variable increment in LOOP
718 (just before the exit condition if it is available and latch block is empty,
719 end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if
720 the increment should be inserted after *BSI. */
722 void
723 standard_iv_increment_position (struct loop *loop, gimple_stmt_iterator *bsi,
724 bool *insert_after)
726 basic_block bb = ip_normal_pos (loop), latch = ip_end_pos (loop);
727 gimple last = last_stmt (latch);
729 if (!bb
730 || (last && gimple_code (last) != GIMPLE_LABEL))
732 *bsi = gsi_last_bb (latch);
733 *insert_after = true;
735 else
737 *bsi = gsi_last_bb (bb);
738 *insert_after = false;
742 /* Copies phi node arguments for duplicated blocks. The index of the first
743 duplicated block is FIRST_NEW_BLOCK. */
745 static void
746 copy_phi_node_args (unsigned first_new_block)
748 unsigned i;
750 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
751 BASIC_BLOCK_FOR_FN (cfun, i)->flags |= BB_DUPLICATED;
753 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
754 add_phi_args_after_copy_bb (BASIC_BLOCK_FOR_FN (cfun, i));
756 for (i = first_new_block; i < (unsigned) last_basic_block_for_fn (cfun); i++)
757 BASIC_BLOCK_FOR_FN (cfun, i)->flags &= ~BB_DUPLICATED;
761 /* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also
762 updates the PHI nodes at start of the copied region. In order to
763 achieve this, only loops whose exits all lead to the same location
764 are handled.
766 Notice that we do not completely update the SSA web after
767 duplication. The caller is responsible for calling update_ssa
768 after the loop has been duplicated. */
770 bool
771 gimple_duplicate_loop_to_header_edge (struct loop *loop, edge e,
772 unsigned int ndupl, sbitmap wont_exit,
773 edge orig, vec<edge> *to_remove,
774 int flags)
776 unsigned first_new_block;
778 if (!loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
779 return false;
780 if (!loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS))
781 return false;
783 first_new_block = last_basic_block_for_fn (cfun);
784 if (!duplicate_loop_to_header_edge (loop, e, ndupl, wont_exit,
785 orig, to_remove, flags))
786 return false;
788 /* Readd the removed phi args for e. */
789 flush_pending_stmts (e);
791 /* Copy the phi node arguments. */
792 copy_phi_node_args (first_new_block);
794 scev_reset ();
796 return true;
799 /* Returns true if we can unroll LOOP FACTOR times. Number
800 of iterations of the loop is returned in NITER. */
802 bool
803 can_unroll_loop_p (struct loop *loop, unsigned factor,
804 struct tree_niter_desc *niter)
806 edge exit;
808 /* Check whether unrolling is possible. We only want to unroll loops
809 for that we are able to determine number of iterations. We also
810 want to split the extra iterations of the loop from its end,
811 therefore we require that the loop has precisely one
812 exit. */
814 exit = single_dom_exit (loop);
815 if (!exit)
816 return false;
818 if (!number_of_iterations_exit (loop, exit, niter, false)
819 || niter->cmp == ERROR_MARK
820 /* Scalar evolutions analysis might have copy propagated
821 the abnormal ssa names into these expressions, hence
822 emitting the computations based on them during loop
823 unrolling might create overlapping life ranges for
824 them, and failures in out-of-ssa. */
825 || contains_abnormal_ssa_name_p (niter->may_be_zero)
826 || contains_abnormal_ssa_name_p (niter->control.base)
827 || contains_abnormal_ssa_name_p (niter->control.step)
828 || contains_abnormal_ssa_name_p (niter->bound))
829 return false;
831 /* And of course, we must be able to duplicate the loop. */
832 if (!can_duplicate_loop_p (loop))
833 return false;
835 /* The final loop should be small enough. */
836 if (tree_num_loop_insns (loop, &eni_size_weights) * factor
837 > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS))
838 return false;
840 return true;
843 /* Determines the conditions that control execution of LOOP unrolled FACTOR
844 times. DESC is number of iterations of LOOP. ENTER_COND is set to
845 condition that must be true if the main loop can be entered.
846 EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing
847 how the exit from the unrolled loop should be controlled. */
849 static void
850 determine_exit_conditions (struct loop *loop, struct tree_niter_desc *desc,
851 unsigned factor, tree *enter_cond,
852 tree *exit_base, tree *exit_step,
853 enum tree_code *exit_cmp, tree *exit_bound)
855 gimple_seq stmts;
856 tree base = desc->control.base;
857 tree step = desc->control.step;
858 tree bound = desc->bound;
859 tree type = TREE_TYPE (step);
860 tree bigstep, delta;
861 tree min = lower_bound_in_type (type, type);
862 tree max = upper_bound_in_type (type, type);
863 enum tree_code cmp = desc->cmp;
864 tree cond = boolean_true_node, assum;
866 /* For pointers, do the arithmetics in the type of step. */
867 base = fold_convert (type, base);
868 bound = fold_convert (type, bound);
870 *enter_cond = boolean_false_node;
871 *exit_base = NULL_TREE;
872 *exit_step = NULL_TREE;
873 *exit_cmp = ERROR_MARK;
874 *exit_bound = NULL_TREE;
875 gcc_assert (cmp != ERROR_MARK);
877 /* We only need to be correct when we answer question
878 "Do at least FACTOR more iterations remain?" in the unrolled loop.
879 Thus, transforming BASE + STEP * i <> BOUND to
880 BASE + STEP * i < BOUND is ok. */
881 if (cmp == NE_EXPR)
883 if (tree_int_cst_sign_bit (step))
884 cmp = GT_EXPR;
885 else
886 cmp = LT_EXPR;
888 else if (cmp == LT_EXPR)
890 gcc_assert (!tree_int_cst_sign_bit (step));
892 else if (cmp == GT_EXPR)
894 gcc_assert (tree_int_cst_sign_bit (step));
896 else
897 gcc_unreachable ();
899 /* The main body of the loop may be entered iff:
901 1) desc->may_be_zero is false.
902 2) it is possible to check that there are at least FACTOR iterations
903 of the loop, i.e., BOUND - step * FACTOR does not overflow.
904 3) # of iterations is at least FACTOR */
906 if (!integer_zerop (desc->may_be_zero))
907 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
908 invert_truthvalue (desc->may_be_zero),
909 cond);
911 bigstep = fold_build2 (MULT_EXPR, type, step,
912 build_int_cst_type (type, factor));
913 delta = fold_build2 (MINUS_EXPR, type, bigstep, step);
914 if (cmp == LT_EXPR)
915 assum = fold_build2 (GE_EXPR, boolean_type_node,
916 bound,
917 fold_build2 (PLUS_EXPR, type, min, delta));
918 else
919 assum = fold_build2 (LE_EXPR, boolean_type_node,
920 bound,
921 fold_build2 (PLUS_EXPR, type, max, delta));
922 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond);
924 bound = fold_build2 (MINUS_EXPR, type, bound, delta);
925 assum = fold_build2 (cmp, boolean_type_node, base, bound);
926 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond);
928 cond = force_gimple_operand (unshare_expr (cond), &stmts, false, NULL_TREE);
929 if (stmts)
930 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
931 /* cond now may be a gimple comparison, which would be OK, but also any
932 other gimple rhs (say a && b). In this case we need to force it to
933 operand. */
934 if (!is_gimple_condexpr (cond))
936 cond = force_gimple_operand (cond, &stmts, true, NULL_TREE);
937 if (stmts)
938 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
940 *enter_cond = cond;
942 base = force_gimple_operand (unshare_expr (base), &stmts, true, NULL_TREE);
943 if (stmts)
944 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
945 bound = force_gimple_operand (unshare_expr (bound), &stmts, true, NULL_TREE);
946 if (stmts)
947 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
949 *exit_base = base;
950 *exit_step = bigstep;
951 *exit_cmp = cmp;
952 *exit_bound = bound;
955 /* Scales the frequencies of all basic blocks in LOOP that are strictly
956 dominated by BB by NUM/DEN. */
958 static void
959 scale_dominated_blocks_in_loop (struct loop *loop, basic_block bb,
960 int num, int den)
962 basic_block son;
964 if (den == 0)
965 return;
967 for (son = first_dom_son (CDI_DOMINATORS, bb);
968 son;
969 son = next_dom_son (CDI_DOMINATORS, son))
971 if (!flow_bb_inside_loop_p (loop, son))
972 continue;
973 scale_bbs_frequencies_int (&son, 1, num, den);
974 scale_dominated_blocks_in_loop (loop, son, num, den);
978 /* Unroll LOOP FACTOR times. DESC describes number of iterations of LOOP.
979 EXIT is the exit of the loop to that DESC corresponds.
981 If N is number of iterations of the loop and MAY_BE_ZERO is the condition
982 under that loop exits in the first iteration even if N != 0,
984 while (1)
986 x = phi (init, next);
988 pre;
989 if (st)
990 break;
991 post;
994 becomes (with possibly the exit conditions formulated a bit differently,
995 avoiding the need to create a new iv):
997 if (MAY_BE_ZERO || N < FACTOR)
998 goto rest;
1002 x = phi (init, next);
1004 pre;
1005 post;
1006 pre;
1007 post;
1009 pre;
1010 post;
1011 N -= FACTOR;
1013 } while (N >= FACTOR);
1015 rest:
1016 init' = phi (init, x);
1018 while (1)
1020 x = phi (init', next);
1022 pre;
1023 if (st)
1024 break;
1025 post;
1028 Before the loop is unrolled, TRANSFORM is called for it (only for the
1029 unrolled loop, but not for its versioned copy). DATA is passed to
1030 TRANSFORM. */
1032 /* Probability in % that the unrolled loop is entered. Just a guess. */
1033 #define PROB_UNROLLED_LOOP_ENTERED 90
1035 void
1036 tree_transform_and_unroll_loop (struct loop *loop, unsigned factor,
1037 edge exit, struct tree_niter_desc *desc,
1038 transform_callback transform,
1039 void *data)
1041 gcond *exit_if;
1042 tree ctr_before, ctr_after;
1043 tree enter_main_cond, exit_base, exit_step, exit_bound;
1044 enum tree_code exit_cmp;
1045 gphi *phi_old_loop, *phi_new_loop, *phi_rest;
1046 gphi_iterator psi_old_loop, psi_new_loop;
1047 tree init, next, new_init;
1048 struct loop *new_loop;
1049 basic_block rest, exit_bb;
1050 edge old_entry, new_entry, old_latch, precond_edge, new_exit;
1051 edge new_nonexit, e;
1052 gimple_stmt_iterator bsi;
1053 use_operand_p op;
1054 bool ok;
1055 unsigned est_niter, prob_entry, scale_unrolled, scale_rest, freq_e, freq_h;
1056 unsigned new_est_niter, i, prob;
1057 unsigned irr = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP;
1058 sbitmap wont_exit;
1059 auto_vec<edge> to_remove;
1061 est_niter = expected_loop_iterations (loop);
1062 determine_exit_conditions (loop, desc, factor,
1063 &enter_main_cond, &exit_base, &exit_step,
1064 &exit_cmp, &exit_bound);
1066 /* Let us assume that the unrolled loop is quite likely to be entered. */
1067 if (integer_nonzerop (enter_main_cond))
1068 prob_entry = REG_BR_PROB_BASE;
1069 else
1070 prob_entry = PROB_UNROLLED_LOOP_ENTERED * REG_BR_PROB_BASE / 100;
1072 /* The values for scales should keep profile consistent, and somewhat close
1073 to correct.
1075 TODO: The current value of SCALE_REST makes it appear that the loop that
1076 is created by splitting the remaining iterations of the unrolled loop is
1077 executed the same number of times as the original loop, and with the same
1078 frequencies, which is obviously wrong. This does not appear to cause
1079 problems, so we do not bother with fixing it for now. To make the profile
1080 correct, we would need to change the probability of the exit edge of the
1081 loop, and recompute the distribution of frequencies in its body because
1082 of this change (scale the frequencies of blocks before and after the exit
1083 by appropriate factors). */
1084 scale_unrolled = prob_entry;
1085 scale_rest = REG_BR_PROB_BASE;
1087 new_loop = loop_version (loop, enter_main_cond, NULL,
1088 prob_entry, scale_unrolled, scale_rest, true);
1089 gcc_assert (new_loop != NULL);
1090 update_ssa (TODO_update_ssa);
1092 /* Determine the probability of the exit edge of the unrolled loop. */
1093 new_est_niter = est_niter / factor;
1095 /* Without profile feedback, loops for that we do not know a better estimate
1096 are assumed to roll 10 times. When we unroll such loop, it appears to
1097 roll too little, and it may even seem to be cold. To avoid this, we
1098 ensure that the created loop appears to roll at least 5 times (but at
1099 most as many times as before unrolling). */
1100 if (new_est_niter < 5)
1102 if (est_niter < 5)
1103 new_est_niter = est_niter;
1104 else
1105 new_est_niter = 5;
1108 /* Prepare the cfg and update the phi nodes. Move the loop exit to the
1109 loop latch (and make its condition dummy, for the moment). */
1110 rest = loop_preheader_edge (new_loop)->src;
1111 precond_edge = single_pred_edge (rest);
1112 split_edge (loop_latch_edge (loop));
1113 exit_bb = single_pred (loop->latch);
1115 /* Since the exit edge will be removed, the frequency of all the blocks
1116 in the loop that are dominated by it must be scaled by
1117 1 / (1 - exit->probability). */
1118 scale_dominated_blocks_in_loop (loop, exit->src,
1119 REG_BR_PROB_BASE,
1120 REG_BR_PROB_BASE - exit->probability);
1122 bsi = gsi_last_bb (exit_bb);
1123 exit_if = gimple_build_cond (EQ_EXPR, integer_zero_node,
1124 integer_zero_node,
1125 NULL_TREE, NULL_TREE);
1127 gsi_insert_after (&bsi, exit_if, GSI_NEW_STMT);
1128 new_exit = make_edge (exit_bb, rest, EDGE_FALSE_VALUE | irr);
1129 rescan_loop_exit (new_exit, true, false);
1131 /* Set the probability of new exit to the same of the old one. Fix
1132 the frequency of the latch block, by scaling it back by
1133 1 - exit->probability. */
1134 new_exit->count = exit->count;
1135 new_exit->probability = exit->probability;
1136 new_nonexit = single_pred_edge (loop->latch);
1137 new_nonexit->probability = REG_BR_PROB_BASE - exit->probability;
1138 new_nonexit->flags = EDGE_TRUE_VALUE;
1139 new_nonexit->count -= exit->count;
1140 if (new_nonexit->count < 0)
1141 new_nonexit->count = 0;
1142 scale_bbs_frequencies_int (&loop->latch, 1, new_nonexit->probability,
1143 REG_BR_PROB_BASE);
1145 old_entry = loop_preheader_edge (loop);
1146 new_entry = loop_preheader_edge (new_loop);
1147 old_latch = loop_latch_edge (loop);
1148 for (psi_old_loop = gsi_start_phis (loop->header),
1149 psi_new_loop = gsi_start_phis (new_loop->header);
1150 !gsi_end_p (psi_old_loop);
1151 gsi_next (&psi_old_loop), gsi_next (&psi_new_loop))
1153 phi_old_loop = psi_old_loop.phi ();
1154 phi_new_loop = psi_new_loop.phi ();
1156 init = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_entry);
1157 op = PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop, new_entry);
1158 gcc_assert (operand_equal_for_phi_arg_p (init, USE_FROM_PTR (op)));
1159 next = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_latch);
1161 /* Prefer using original variable as a base for the new ssa name.
1162 This is necessary for virtual ops, and useful in order to avoid
1163 losing debug info for real ops. */
1164 if (TREE_CODE (next) == SSA_NAME
1165 && useless_type_conversion_p (TREE_TYPE (next),
1166 TREE_TYPE (init)))
1167 new_init = copy_ssa_name (next);
1168 else if (TREE_CODE (init) == SSA_NAME
1169 && useless_type_conversion_p (TREE_TYPE (init),
1170 TREE_TYPE (next)))
1171 new_init = copy_ssa_name (init);
1172 else if (useless_type_conversion_p (TREE_TYPE (next), TREE_TYPE (init)))
1173 new_init = make_temp_ssa_name (TREE_TYPE (next), NULL, "unrinittmp");
1174 else
1175 new_init = make_temp_ssa_name (TREE_TYPE (init), NULL, "unrinittmp");
1177 phi_rest = create_phi_node (new_init, rest);
1179 add_phi_arg (phi_rest, init, precond_edge, UNKNOWN_LOCATION);
1180 add_phi_arg (phi_rest, next, new_exit, UNKNOWN_LOCATION);
1181 SET_USE (op, new_init);
1184 remove_path (exit);
1186 /* Transform the loop. */
1187 if (transform)
1188 (*transform) (loop, data);
1190 /* Unroll the loop and remove the exits in all iterations except for the
1191 last one. */
1192 wont_exit = sbitmap_alloc (factor);
1193 bitmap_ones (wont_exit);
1194 bitmap_clear_bit (wont_exit, factor - 1);
1196 ok = gimple_duplicate_loop_to_header_edge
1197 (loop, loop_latch_edge (loop), factor - 1,
1198 wont_exit, new_exit, &to_remove, DLTHE_FLAG_UPDATE_FREQ);
1199 free (wont_exit);
1200 gcc_assert (ok);
1202 FOR_EACH_VEC_ELT (to_remove, i, e)
1204 ok = remove_path (e);
1205 gcc_assert (ok);
1207 update_ssa (TODO_update_ssa);
1209 /* Ensure that the frequencies in the loop match the new estimated
1210 number of iterations, and change the probability of the new
1211 exit edge. */
1212 freq_h = loop->header->frequency;
1213 freq_e = EDGE_FREQUENCY (loop_preheader_edge (loop));
1214 if (freq_h != 0)
1215 scale_loop_frequencies (loop, freq_e * (new_est_niter + 1), freq_h);
1217 exit_bb = single_pred (loop->latch);
1218 new_exit = find_edge (exit_bb, rest);
1219 new_exit->count = loop_preheader_edge (loop)->count;
1220 new_exit->probability = REG_BR_PROB_BASE / (new_est_niter + 1);
1222 rest->count += new_exit->count;
1223 rest->frequency += EDGE_FREQUENCY (new_exit);
1225 new_nonexit = single_pred_edge (loop->latch);
1226 prob = new_nonexit->probability;
1227 new_nonexit->probability = REG_BR_PROB_BASE - new_exit->probability;
1228 new_nonexit->count = exit_bb->count - new_exit->count;
1229 if (new_nonexit->count < 0)
1230 new_nonexit->count = 0;
1231 if (prob > 0)
1232 scale_bbs_frequencies_int (&loop->latch, 1, new_nonexit->probability,
1233 prob);
1235 /* Finally create the new counter for number of iterations and add the new
1236 exit instruction. */
1237 bsi = gsi_last_nondebug_bb (exit_bb);
1238 exit_if = as_a <gcond *> (gsi_stmt (bsi));
1239 create_iv (exit_base, exit_step, NULL_TREE, loop,
1240 &bsi, false, &ctr_before, &ctr_after);
1241 gimple_cond_set_code (exit_if, exit_cmp);
1242 gimple_cond_set_lhs (exit_if, ctr_after);
1243 gimple_cond_set_rhs (exit_if, exit_bound);
1244 update_stmt (exit_if);
1246 #ifdef ENABLE_CHECKING
1247 verify_flow_info ();
1248 verify_loop_structure ();
1249 verify_loop_closed_ssa (true);
1250 #endif
1253 /* Wrapper over tree_transform_and_unroll_loop for case we do not
1254 want to transform the loop before unrolling. The meaning
1255 of the arguments is the same as for tree_transform_and_unroll_loop. */
1257 void
1258 tree_unroll_loop (struct loop *loop, unsigned factor,
1259 edge exit, struct tree_niter_desc *desc)
1261 tree_transform_and_unroll_loop (loop, factor, exit, desc,
1262 NULL, NULL);
1265 /* Rewrite the phi node at position PSI in function of the main
1266 induction variable MAIN_IV and insert the generated code at GSI. */
1268 static void
1269 rewrite_phi_with_iv (loop_p loop,
1270 gphi_iterator *psi,
1271 gimple_stmt_iterator *gsi,
1272 tree main_iv)
1274 affine_iv iv;
1275 gassign *stmt;
1276 gphi *phi = psi->phi ();
1277 tree atype, mtype, val, res = PHI_RESULT (phi);
1279 if (virtual_operand_p (res) || res == main_iv)
1281 gsi_next (psi);
1282 return;
1285 if (!simple_iv (loop, loop, res, &iv, true))
1287 gsi_next (psi);
1288 return;
1291 remove_phi_node (psi, false);
1293 atype = TREE_TYPE (res);
1294 mtype = POINTER_TYPE_P (atype) ? sizetype : atype;
1295 val = fold_build2 (MULT_EXPR, mtype, unshare_expr (iv.step),
1296 fold_convert (mtype, main_iv));
1297 val = fold_build2 (POINTER_TYPE_P (atype)
1298 ? POINTER_PLUS_EXPR : PLUS_EXPR,
1299 atype, unshare_expr (iv.base), val);
1300 val = force_gimple_operand_gsi (gsi, val, false, NULL_TREE, true,
1301 GSI_SAME_STMT);
1302 stmt = gimple_build_assign (res, val);
1303 gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
1306 /* Rewrite all the phi nodes of LOOP in function of the main induction
1307 variable MAIN_IV. */
1309 static void
1310 rewrite_all_phi_nodes_with_iv (loop_p loop, tree main_iv)
1312 unsigned i;
1313 basic_block *bbs = get_loop_body_in_dom_order (loop);
1314 gphi_iterator psi;
1316 for (i = 0; i < loop->num_nodes; i++)
1318 basic_block bb = bbs[i];
1319 gimple_stmt_iterator gsi = gsi_after_labels (bb);
1321 if (bb->loop_father != loop)
1322 continue;
1324 for (psi = gsi_start_phis (bb); !gsi_end_p (psi); )
1325 rewrite_phi_with_iv (loop, &psi, &gsi, main_iv);
1328 free (bbs);
1331 /* Bases all the induction variables in LOOP on a single induction
1332 variable (unsigned with base 0 and step 1), whose final value is
1333 compared with *NIT. When the IV type precision has to be larger
1334 than *NIT type precision, *NIT is converted to the larger type, the
1335 conversion code is inserted before the loop, and *NIT is updated to
1336 the new definition. When BUMP_IN_LATCH is true, the induction
1337 variable is incremented in the loop latch, otherwise it is
1338 incremented in the loop header. Return the induction variable that
1339 was created. */
1341 tree
1342 canonicalize_loop_ivs (struct loop *loop, tree *nit, bool bump_in_latch)
1344 unsigned precision = TYPE_PRECISION (TREE_TYPE (*nit));
1345 unsigned original_precision = precision;
1346 tree type, var_before;
1347 gimple_stmt_iterator gsi;
1348 gphi_iterator psi;
1349 gcond *stmt;
1350 edge exit = single_dom_exit (loop);
1351 gimple_seq stmts;
1352 machine_mode mode;
1353 bool unsigned_p = false;
1355 for (psi = gsi_start_phis (loop->header);
1356 !gsi_end_p (psi); gsi_next (&psi))
1358 gphi *phi = psi.phi ();
1359 tree res = PHI_RESULT (phi);
1360 bool uns;
1362 type = TREE_TYPE (res);
1363 if (virtual_operand_p (res)
1364 || (!INTEGRAL_TYPE_P (type)
1365 && !POINTER_TYPE_P (type))
1366 || TYPE_PRECISION (type) < precision)
1367 continue;
1369 uns = POINTER_TYPE_P (type) | TYPE_UNSIGNED (type);
1371 if (TYPE_PRECISION (type) > precision)
1372 unsigned_p = uns;
1373 else
1374 unsigned_p |= uns;
1376 precision = TYPE_PRECISION (type);
1379 mode = smallest_mode_for_size (precision, MODE_INT);
1380 precision = GET_MODE_PRECISION (mode);
1381 type = build_nonstandard_integer_type (precision, unsigned_p);
1383 if (original_precision != precision)
1385 *nit = fold_convert (type, *nit);
1386 *nit = force_gimple_operand (*nit, &stmts, true, NULL_TREE);
1387 if (stmts)
1388 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
1391 if (bump_in_latch)
1392 gsi = gsi_last_bb (loop->latch);
1393 else
1394 gsi = gsi_last_nondebug_bb (loop->header);
1395 create_iv (build_int_cst_type (type, 0), build_int_cst (type, 1), NULL_TREE,
1396 loop, &gsi, bump_in_latch, &var_before, NULL);
1398 rewrite_all_phi_nodes_with_iv (loop, var_before);
1400 stmt = as_a <gcond *> (last_stmt (exit->src));
1401 /* Make the loop exit if the control condition is not satisfied. */
1402 if (exit->flags & EDGE_TRUE_VALUE)
1404 edge te, fe;
1406 extract_true_false_edges_from_block (exit->src, &te, &fe);
1407 te->flags = EDGE_FALSE_VALUE;
1408 fe->flags = EDGE_TRUE_VALUE;
1410 gimple_cond_set_code (stmt, LT_EXPR);
1411 gimple_cond_set_lhs (stmt, var_before);
1412 gimple_cond_set_rhs (stmt, *nit);
1413 update_stmt (stmt);
1415 return var_before;