1 /* If-conversion for vectorizer.
2 Copyright (C) 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Devang Patel <dpatel@apple.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This pass implements tree level if-conversion transformation of loops.
23 Initial goal is to help vectorizer vectorize loops with conditions.
25 A short description of if-conversion:
27 o Decide if a loop is if-convertible or not.
28 o Walk all loop basic blocks in breadth first order (BFS order).
29 o Remove conditional statements (at the end of basic block)
30 and propagate condition into destination basic blocks'
32 o Replace modify expression with conditional modify expression
33 using current basic block's condition.
34 o Merge all basic blocks
35 o Replace phi nodes with conditional modify expr
36 o Merge all basic blocks into header
38 Sample transformation:
43 # i_23 = PHI <0(0), i_18(10)>;
46 if (j_15 > 41) goto <L1>; else goto <L17>;
53 # iftmp.2_4 = PHI <0(8), 42(2)>;
57 if (i_18 <= 15) goto <L19>; else goto <L18>;
67 # i_23 = PHI <0(0), i_18(10)>;
72 iftmp.2_4 = j_15 > 41 ? 42 : 0;
75 if (i_18 <= 15) goto <L19>; else goto <L18>;
85 #include "coretypes.h"
94 #include "basic-block.h"
95 #include "diagnostic.h"
96 #include "tree-flow.h"
97 #include "tree-dump.h"
99 #include "tree-chrec.h"
100 #include "tree-data-ref.h"
101 #include "tree-scalar-evolution.h"
102 #include "tree-pass.h"
105 /* local function prototypes */
106 static void main_tree_if_conversion (void);
107 static tree tree_if_convert_stmt (struct loop *loop, tree, tree,
108 block_stmt_iterator *);
109 static void tree_if_convert_cond_expr (struct loop *, tree, tree,
110 block_stmt_iterator *);
111 static bool if_convertible_phi_p (struct loop *, basic_block, tree);
112 static bool if_convertible_modify_expr_p (struct loop *, basic_block, tree);
113 static bool if_convertible_stmt_p (struct loop *, basic_block, tree);
114 static bool if_convertible_bb_p (struct loop *, basic_block, bool);
115 static bool if_convertible_loop_p (struct loop *, bool);
116 static void add_to_predicate_list (basic_block, tree);
117 static tree add_to_dst_predicate_list (struct loop * loop, basic_block, tree, tree,
118 block_stmt_iterator *);
119 static void clean_predicate_lists (struct loop *loop);
120 static basic_block find_phi_replacement_condition (basic_block, tree *,
121 block_stmt_iterator *);
122 static void replace_phi_with_cond_modify_expr (tree, tree, basic_block,
123 block_stmt_iterator *);
124 static void process_phi_nodes (struct loop *);
125 static void combine_blocks (struct loop *);
126 static tree ifc_temp_var (tree, tree);
127 static bool pred_blocks_visited_p (basic_block, bitmap *);
128 static basic_block * get_loop_body_in_if_conv_order (const struct loop *loop);
129 static bool bb_with_exit_edge_p (struct loop *, basic_block);
131 /* List of basic blocks in if-conversion-suitable order. */
132 static basic_block *ifc_bbs;
135 Apply if-conversion to the LOOP. Return true if successful otherwise return
136 false. If false is returned then loop remains unchanged.
137 FOR_VECTORIZER is a boolean flag. It indicates whether if-conversion is used
138 for vectorizer or not. If it is used for vectorizer, additional checks are
139 used. (Vectorization checks are not yet implemented). */
142 tree_if_conversion (struct loop *loop, bool for_vectorizer)
145 block_stmt_iterator itr;
151 /* if-conversion is not appropriate for all loops. First, check if loop is
152 if-convertible or not. */
153 if (!if_convertible_loop_p (loop, for_vectorizer))
155 if (dump_file && (dump_flags & TDF_DETAILS))
156 fprintf (dump_file,"-------------------------\n");
162 free_dominance_info (CDI_POST_DOMINATORS);
168 /* Do actual work now. */
169 for (i = 0; i < loop->num_nodes; i++)
173 /* Update condition using predicate list. */
176 /* Process all statements in this basic block.
177 Remove conditional expression, if any, and annotate
178 destination basic block(s) appropriately. */
179 for (itr = bsi_start (bb); !bsi_end_p (itr); /* empty */)
181 tree t = bsi_stmt (itr);
182 cond = tree_if_convert_stmt (loop, t, cond, &itr);
183 if (!bsi_end_p (itr))
187 /* If current bb has only one successor, then consider it as an
188 unconditional goto. */
189 if (single_succ_p (bb))
191 basic_block bb_n = single_succ (bb);
192 if (cond != NULL_TREE)
193 add_to_predicate_list (bb_n, cond);
198 /* Now, all statements are if-converted and basic blocks are
199 annotated appropriately. Combine all basic block into one huge
201 combine_blocks (loop);
204 clean_predicate_lists (loop);
211 /* if-convert stmt T which is part of LOOP.
212 If T is a MODIFY_EXPR than it is converted into conditional modify
213 expression using COND. For conditional expressions, add condition in the
214 destination basic block's predicate list and remove conditional
215 expression itself. BSI is the iterator used to traverse statements of
216 loop. It is used here when it is required to delete current statement. */
219 tree_if_convert_stmt (struct loop * loop, tree t, tree cond,
220 block_stmt_iterator *bsi)
222 if (dump_file && (dump_flags & TDF_DETAILS))
224 fprintf (dump_file, "------if-convert stmt\n");
225 print_generic_stmt (dump_file, t, TDF_SLIM);
226 print_generic_stmt (dump_file, cond, TDF_SLIM);
229 switch (TREE_CODE (t))
231 /* Labels are harmless here. */
236 /* This modify_expr is killing previous value of LHS. Appropriate value will
237 be selected by PHI node based on condition. It is possible that before
238 this transformation, PHI nodes was selecting default value and now it will
239 use this new value. This is OK because it does not change validity the
244 /* Unconditional goto */
245 add_to_predicate_list (bb_for_stmt (TREE_OPERAND (t, 1)), cond);
251 /* Update destination blocks' predicate list and remove this
252 condition expression. */
253 tree_if_convert_cond_expr (loop, t, cond, bsi);
263 /* STMT is COND_EXPR. Update two destination's predicate list.
264 Remove COND_EXPR, if it is not the loop exit condition. Otherwise
265 update loop exit condition appropriately. BSI is the iterator
266 used to traverse statement list. STMT is part of loop LOOP. */
269 tree_if_convert_cond_expr (struct loop *loop, tree stmt, tree cond,
270 block_stmt_iterator *bsi)
273 edge true_edge, false_edge;
275 gcc_assert (TREE_CODE (stmt) == COND_EXPR);
277 c = COND_EXPR_COND (stmt);
279 /* Create temp. for condition. */
280 if (!is_gimple_condexpr (c))
283 new_stmt = ifc_temp_var (TREE_TYPE (c), unshare_expr (c));
284 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
285 c = TREE_OPERAND (new_stmt, 0);
288 extract_true_false_edges_from_block (bb_for_stmt (stmt),
289 &true_edge, &false_edge);
291 /* Add new condition into destination's predicate list. */
293 /* If 'c' is true then TRUE_EDGE is taken. */
294 add_to_dst_predicate_list (loop, true_edge->dest, cond,
295 unshare_expr (c), bsi);
297 if (!is_gimple_reg(c) && is_gimple_condexpr (c))
300 new_stmt = ifc_temp_var (TREE_TYPE (c), unshare_expr (c));
301 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
302 c = TREE_OPERAND (new_stmt, 0);
305 /* If 'c' is false then FALSE_EDGE is taken. */
306 c2 = invert_truthvalue (unshare_expr (c));
307 add_to_dst_predicate_list (loop, false_edge->dest, cond, c2, bsi);
309 /* Now this conditional statement is redundant. Remove it.
310 But, do not remove exit condition! Update exit condition
311 using new condition. */
312 if (!bb_with_exit_edge_p (loop, bb_for_stmt (stmt)))
320 /* Return true, iff PHI is if-convertible. PHI is part of loop LOOP
321 and it belongs to basic block BB.
322 PHI is not if-convertible
323 - if it has more than 2 arguments.
324 - Virtual PHI is immediately used in another PHI node. */
327 if_convertible_phi_p (struct loop *loop, basic_block bb, tree phi)
329 if (dump_file && (dump_flags & TDF_DETAILS))
331 fprintf (dump_file, "-------------------------\n");
332 print_generic_stmt (dump_file, phi, TDF_SLIM);
335 if (bb != loop->header && PHI_NUM_ARGS (phi) != 2)
337 if (dump_file && (dump_flags & TDF_DETAILS))
338 fprintf (dump_file, "More than two phi node args.\n");
342 if (!is_gimple_reg (SSA_NAME_VAR (PHI_RESULT (phi))))
344 imm_use_iterator imm_iter;
346 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, PHI_RESULT (phi))
348 if (TREE_CODE (USE_STMT (use_p)) == PHI_NODE)
350 if (dump_file && (dump_flags & TDF_DETAILS))
351 fprintf (dump_file, "Difficult to handle this virtual phi.\n");
360 /* Return true, if M_EXPR is if-convertible.
361 MODIFY_EXPR is not if-convertible if,
364 - LHS is not var decl.
365 MODIFY_EXPR is part of block BB, which is inside loop LOOP.
369 if_convertible_modify_expr_p (struct loop *loop, basic_block bb, tree m_expr)
371 if (dump_file && (dump_flags & TDF_DETAILS))
373 fprintf (dump_file, "-------------------------\n");
374 print_generic_stmt (dump_file, m_expr, TDF_SLIM);
377 /* Be conservative and do not handle immovable expressions. */
378 if (movement_possibility (m_expr) == MOVE_IMPOSSIBLE)
380 if (dump_file && (dump_flags & TDF_DETAILS))
381 fprintf (dump_file, "stmt is movable. Don't take risk\n");
385 /* See if it needs speculative loading or not. */
386 if (bb != loop->header
387 && tree_could_trap_p (TREE_OPERAND (m_expr, 1)))
389 if (dump_file && (dump_flags & TDF_DETAILS))
390 fprintf (dump_file, "tree could trap...\n");
394 if (TREE_CODE (TREE_OPERAND (m_expr, 1)) == CALL_EXPR)
396 if (dump_file && (dump_flags & TDF_DETAILS))
397 fprintf (dump_file, "CALL_EXPR \n");
401 if (TREE_CODE (TREE_OPERAND (m_expr, 0)) != SSA_NAME
402 && bb != loop->header
403 && !bb_with_exit_edge_p (loop, bb))
405 if (dump_file && (dump_flags & TDF_DETAILS))
407 fprintf (dump_file, "LHS is not var\n");
408 print_generic_stmt (dump_file, m_expr, TDF_SLIM);
417 /* Return true, iff STMT is if-convertible.
418 Statement is if-convertible if,
419 - It is if-convertible MODIFY_EXPR
420 - IT is LABEL_EXPR, GOTO_EXPR or COND_EXPR.
421 STMT is inside block BB, which is inside loop LOOP. */
424 if_convertible_stmt_p (struct loop *loop, basic_block bb, tree stmt)
426 switch (TREE_CODE (stmt))
433 if (!if_convertible_modify_expr_p (loop, bb, stmt))
442 /* Don't know what to do with 'em so don't do anything. */
443 if (dump_file && (dump_flags & TDF_DETAILS))
445 fprintf (dump_file, "don't know what to do\n");
446 print_generic_stmt (dump_file, stmt, TDF_SLIM);
455 /* Return true, iff BB is if-convertible.
456 Note: This routine does _not_ check basic block statements and phis.
457 Basic block is not if-convertible if,
458 - Basic block is non-empty and it is after exit block (in BFS order).
459 - Basic block is after exit block but before latch.
460 - Basic block edge(s) is not normal.
461 EXIT_BB_SEEN is true if basic block with exit edge is already seen.
462 BB is inside loop LOOP. */
465 if_convertible_bb_p (struct loop *loop, basic_block bb, bool exit_bb_seen)
470 if (dump_file && (dump_flags & TDF_DETAILS))
471 fprintf (dump_file, "----------[%d]-------------\n", bb->index);
475 if (bb != loop->latch)
477 if (dump_file && (dump_flags & TDF_DETAILS))
478 fprintf (dump_file, "basic block after exit bb but before latch\n");
481 else if (!empty_block_p (bb))
483 if (dump_file && (dump_flags & TDF_DETAILS))
484 fprintf (dump_file, "non empty basic block after exit bb\n");
489 /* Be less adventurous and handle only normal edges. */
490 FOR_EACH_EDGE (e, ei, bb->succs)
492 (EDGE_ABNORMAL_CALL | EDGE_EH | EDGE_ABNORMAL | EDGE_IRREDUCIBLE_LOOP))
494 if (dump_file && (dump_flags & TDF_DETAILS))
495 fprintf (dump_file,"Difficult to handle edges\n");
502 /* Return true, iff LOOP is if-convertible.
503 LOOP is if-convertible if,
505 - It has two or more basic blocks.
506 - It has only one exit.
507 - Loop header is not the exit edge.
508 - If its basic blocks and phi nodes are if convertible. See above for
510 FOR_VECTORIZER enables vectorizer specific checks. For example, support
511 for vector conditions, data dependency checks etc.. (Not implemented yet). */
514 if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
518 block_stmt_iterator itr;
522 bool exit_bb_seen = false;
524 /* Handle only inner most loop. */
525 if (!loop || loop->inner)
527 if (dump_file && (dump_flags & TDF_DETAILS))
528 fprintf (dump_file, "not inner most loop\n");
532 /* If only one block, no need for if-conversion. */
533 if (loop->num_nodes <= 2)
535 if (dump_file && (dump_flags & TDF_DETAILS))
536 fprintf (dump_file, "less than 2 basic blocks\n");
540 /* More than one loop exit is too much to handle. */
541 if (!loop->single_exit)
543 if (dump_file && (dump_flags & TDF_DETAILS))
544 fprintf (dump_file, "multiple exits\n");
548 /* ??? Check target's vector conditional operation support for vectorizer. */
550 /* If one of the loop header's edge is exit edge then do not apply
552 FOR_EACH_EDGE (e, ei, loop->header->succs)
554 if (loop_exit_edge_p (loop, e))
558 calculate_dominance_info (CDI_DOMINATORS);
559 calculate_dominance_info (CDI_POST_DOMINATORS);
561 /* Allow statements that can be handled during if-conversion. */
562 ifc_bbs = get_loop_body_in_if_conv_order (loop);
565 if (dump_file && (dump_flags & TDF_DETAILS))
566 fprintf (dump_file,"Irreducible loop\n");
567 free_dominance_info (CDI_POST_DOMINATORS);
571 for (i = 0; i < loop->num_nodes; i++)
575 if (!if_convertible_bb_p (loop, bb, exit_bb_seen))
578 /* Check statements. */
579 for (itr = bsi_start (bb); !bsi_end_p (itr); bsi_next (&itr))
580 if (!if_convertible_stmt_p (loop, bb, bsi_stmt (itr)))
582 /* ??? Check data dependency for vectorizer. */
584 /* What about phi nodes ? */
585 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
586 if (!if_convertible_phi_p (loop, bb, phi))
589 if (bb_with_exit_edge_p (loop, bb))
593 /* OK. Did not find any potential issues so go ahead in if-convert
594 this loop. Now there is no looking back. */
596 fprintf (dump_file,"Applying if-conversion\n");
598 free_dominance_info (CDI_POST_DOMINATORS);
602 /* Add condition COND into predicate list of basic block BB. */
605 add_to_predicate_list (basic_block bb, tree new_cond)
610 cond = fold (build (TRUTH_OR_EXPR, boolean_type_node,
611 unshare_expr (cond), new_cond));
618 /* Add condition COND into BB's predicate list. PREV_COND is
619 existing condition. */
622 add_to_dst_predicate_list (struct loop * loop, basic_block bb,
623 tree prev_cond, tree cond,
624 block_stmt_iterator *bsi)
626 tree new_cond = NULL_TREE;
628 if (!flow_bb_inside_loop_p (loop, bb))
631 if (prev_cond == boolean_true_node || !prev_cond)
632 new_cond = unshare_expr (cond);
636 tree tmp_stmt = NULL_TREE;
637 tree tmp_stmts1 = NULL_TREE;
638 tree tmp_stmts2 = NULL_TREE;
639 prev_cond = force_gimple_operand (unshare_expr (prev_cond),
640 &tmp_stmts1, true, NULL);
642 bsi_insert_before (bsi, tmp_stmts1, BSI_SAME_STMT);
644 cond = force_gimple_operand (unshare_expr (cond),
645 &tmp_stmts2, true, NULL);
647 bsi_insert_before (bsi, tmp_stmts2, BSI_SAME_STMT);
649 /* new_cond == prev_cond AND cond */
650 tmp = build (TRUTH_AND_EXPR, boolean_type_node,
651 unshare_expr (prev_cond), cond);
652 tmp_stmt = ifc_temp_var (boolean_type_node, tmp);
653 bsi_insert_before (bsi, tmp_stmt, BSI_SAME_STMT);
654 new_cond = TREE_OPERAND (tmp_stmt, 0);
656 add_to_predicate_list (bb, new_cond);
660 /* During if-conversion aux field from basic block is used to hold predicate
661 list. Clean each basic block's predicate list for the given LOOP. */
664 clean_predicate_lists (struct loop *loop)
668 bb = get_loop_body (loop);
669 for (i = 0; i < loop->num_nodes; i++)
675 /* Basic block BB has two predecessors. Using predecessor's aux field, set
676 appropriate condition COND for the PHI node replacement. Return true block
677 whose phi arguments are selected when cond is true. */
680 find_phi_replacement_condition (basic_block bb, tree *cond,
681 block_stmt_iterator *bsi)
684 basic_block p1 = NULL;
685 basic_block p2 = NULL;
686 basic_block true_bb = NULL;
690 FOR_EACH_EDGE (e, ei, bb->preds)
701 /* Use condition that is not TRUTH_NOT_EXPR in conditional modify expr. */
703 if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
714 /* Create temp. for the condition. Vectorizer prefers to have gimple
715 value as condition. Various targets use different means to communicate
716 condition in vector compare operation. Using gimple value allows compiler
717 to emit vector compare and select RTL without exposing compare's result. */
718 if (!is_gimple_reg (*cond) && !is_gimple_condexpr (*cond))
722 new_stmt = ifc_temp_var (TREE_TYPE (*cond), unshare_expr (*cond));
723 bsi_insert_after (bsi, new_stmt, BSI_SAME_STMT);
725 *cond = TREE_OPERAND (new_stmt, 0);
734 /* Replace PHI node with conditional modify expr using COND.
735 This routine does not handle PHI nodes with more than two arguments.
737 S1: A = PHI <x1(1), x2(5)
739 S2: A = cond ? x1 : x2;
740 S2 is inserted at the top of basic block's statement list.
741 When COND is true, phi arg from TRUE_BB is selected.
745 replace_phi_with_cond_modify_expr (tree phi, tree cond, basic_block true_bb,
746 block_stmt_iterator *bsi)
753 gcc_assert (TREE_CODE (phi) == PHI_NODE);
755 /* If this is not filtered earlier, then now it is too late. */
756 gcc_assert (PHI_NUM_ARGS (phi) == 2);
758 /* Find basic block and initialize iterator. */
759 bb = bb_for_stmt (phi);
761 new_stmt = NULL_TREE;
765 /* Use condition that is not TRUTH_NOT_EXPR in conditional modify expr. */
766 if (EDGE_PRED (bb, 1)->src == true_bb)
768 arg_0 = PHI_ARG_DEF (phi, 1);
769 arg_1 = PHI_ARG_DEF (phi, 0);
773 arg_0 = PHI_ARG_DEF (phi, 0);
774 arg_1 = PHI_ARG_DEF (phi, 1);
777 /* Build new RHS using selected condition and arguments. */
778 rhs = build (COND_EXPR, TREE_TYPE (PHI_RESULT (phi)),
779 unshare_expr (cond), unshare_expr (arg_0),
780 unshare_expr (arg_1));
782 /* Create new MODIFY expression using RHS. */
783 new_stmt = build (MODIFY_EXPR, TREE_TYPE (PHI_RESULT (phi)),
784 unshare_expr (PHI_RESULT (phi)), rhs);
786 /* Make new statement definition of the original phi result. */
787 SSA_NAME_DEF_STMT (PHI_RESULT (phi)) = new_stmt;
789 /* Set basic block and insert using iterator. */
790 set_bb_for_stmt (new_stmt, bb);
792 bsi_insert_after (bsi, new_stmt, BSI_SAME_STMT);
795 update_stmt (new_stmt);
797 if (dump_file && (dump_flags & TDF_DETAILS))
799 fprintf (dump_file, "new phi replacement stmt\n");
800 print_generic_stmt (dump_file, new_stmt, TDF_SLIM);
804 /* Process phi nodes for the given LOOP. Replace phi nodes with cond
808 process_phi_nodes (struct loop *loop)
811 unsigned int orig_loop_num_nodes = loop->num_nodes;
814 /* Replace phi nodes with cond. modify expr. */
815 for (i = 1; i < orig_loop_num_nodes; i++)
818 block_stmt_iterator bsi;
819 basic_block true_bb = NULL;
822 if (bb == loop->header)
825 phi = phi_nodes (bb);
826 bsi = bsi_after_labels (bb);
828 /* BB has two predecessors. Using predecessor's aux field, set
829 appropriate condition for the PHI node replacement. */
831 true_bb = find_phi_replacement_condition (bb, &cond, &bsi);
835 tree next = PHI_CHAIN (phi);
836 replace_phi_with_cond_modify_expr (phi, cond, true_bb, &bsi);
837 release_phi_node (phi);
840 bb_ann (bb)->phi_nodes = NULL;
845 /* Combine all basic block from the given LOOP into one or two super
846 basic block. Replace PHI nodes with conditional modify expression. */
849 combine_blocks (struct loop *loop)
851 basic_block bb, exit_bb, merge_target_bb;
852 unsigned int orig_loop_num_nodes = loop->num_nodes;
854 unsigned int n_exits;
856 get_loop_exit_edges (loop, &n_exits);
857 /* Process phi nodes to prepare blocks for merge. */
858 process_phi_nodes (loop);
862 /* Merge basic blocks */
863 merge_target_bb = loop->header;
864 for (i = 1; i < orig_loop_num_nodes; i++)
867 block_stmt_iterator bsi;
868 tree_stmt_iterator last;
872 if (!exit_bb && bb_with_exit_edge_p (loop, bb))
879 /* Connect this node with loop header. */
880 make_edge (ifc_bbs[0], bb, EDGE_FALLTHRU);
881 set_immediate_dominator (CDI_DOMINATORS, bb, ifc_bbs[0]);
883 if (exit_bb != loop->latch)
885 /* Redirect non-exit edge to loop->latch. */
886 FOR_EACH_EDGE (e, ei, bb->succs)
888 if (!loop_exit_edge_p (loop, e))
890 redirect_edge_and_branch (e, loop->latch);
891 set_immediate_dominator (CDI_DOMINATORS, loop->latch, bb);
898 if (bb == loop->latch && empty_block_p (bb))
901 /* It is time to remove this basic block. First remove edges. */
902 while (EDGE_COUNT (bb->preds) > 0)
903 remove_edge (EDGE_PRED (bb, 0));
905 /* This is loop latch and loop does not have exit then do not
906 delete this basic block. Just remove its PREDS and reconnect
907 loop->header and loop->latch blocks. */
908 if (bb == loop->latch && n_exits == 0)
910 make_edge (loop->header, loop->latch, EDGE_FALLTHRU);
911 set_immediate_dominator (CDI_DOMINATORS, loop->latch, loop->header);
915 while (EDGE_COUNT (bb->succs) > 0)
916 remove_edge (EDGE_SUCC (bb, 0));
918 /* Remove labels and make stmts member of loop->header. */
919 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
921 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
925 set_bb_for_stmt (bsi_stmt (bsi), merge_target_bb);
930 /* Update stmt list. */
931 last = tsi_last (merge_target_bb->stmt_list);
932 tsi_link_after (&last, bb->stmt_list, TSI_NEW_STMT);
933 bb->stmt_list = NULL;
935 /* Update dominator info. */
936 if (dom_computed[CDI_DOMINATORS])
937 delete_from_dominance_info (CDI_DOMINATORS, bb);
938 if (dom_computed[CDI_POST_DOMINATORS])
939 delete_from_dominance_info (CDI_POST_DOMINATORS, bb);
941 /* Remove basic block. */
942 if (bb == loop->latch)
943 loop->latch = merge_target_bb;
944 remove_bb_from_loops (bb);
948 /* Now if possible, merge loop header and block with exit edge.
949 This reduces number of basic blocks to 2. Auto vectorizer addresses
950 loops with two nodes only. FIXME: Use cleanup_tree_cfg(). */
952 && loop->header != loop->latch
953 && exit_bb != loop->latch
954 && empty_block_p (loop->latch))
956 if (can_merge_blocks_p (loop->header, exit_bb))
958 remove_bb_from_loops (exit_bb);
959 merge_blocks (loop->header, exit_bb);
964 /* Make new temp variable of type TYPE. Add MODIFY_EXPR to assign EXP
965 to the new variable. */
968 ifc_temp_var (tree type, tree exp)
970 const char *name = "_ifc_";
971 tree var, stmt, new_name;
973 if (is_gimple_reg (exp))
976 /* Create new temporary variable. */
977 var = create_tmp_var (type, name);
978 add_referenced_tmp_var (var);
980 /* Build new statement to assign EXP to new variable. */
981 stmt = build (MODIFY_EXPR, type, var, exp);
983 /* Get SSA name for the new variable and set make new statement
984 its definition statement. */
985 new_name = make_ssa_name (var, stmt);
986 TREE_OPERAND (stmt, 0) = new_name;
987 SSA_NAME_DEF_STMT (new_name) = stmt;
993 /* Return TRUE iff, all pred blocks of BB are visited.
994 Bitmap VISITED keeps history of visited blocks. */
997 pred_blocks_visited_p (basic_block bb, bitmap *visited)
1001 FOR_EACH_EDGE (e, ei, bb->preds)
1002 if (!bitmap_bit_p (*visited, e->src->index))
1008 /* Get body of a LOOP in suitable order for if-conversion.
1009 It is caller's responsibility to deallocate basic block
1010 list. If-conversion suitable order is, BFS order with one
1011 additional constraint. Select block in BFS block, if all
1012 pred are already selected. */
1014 static basic_block *
1015 get_loop_body_in_if_conv_order (const struct loop *loop)
1017 basic_block *blocks, *blocks_in_bfs_order;
1020 unsigned int index = 0;
1021 unsigned int visited_count = 0;
1023 gcc_assert (loop->num_nodes);
1024 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
1026 blocks = xcalloc (loop->num_nodes, sizeof (basic_block));
1027 visited = BITMAP_ALLOC (NULL);
1029 blocks_in_bfs_order = get_loop_body_in_bfs_order (loop);
1032 while (index < loop->num_nodes)
1034 bb = blocks_in_bfs_order [index];
1036 if (bb->flags & BB_IRREDUCIBLE_LOOP)
1038 free (blocks_in_bfs_order);
1039 BITMAP_FREE (visited);
1043 if (!bitmap_bit_p (visited, bb->index))
1045 if (pred_blocks_visited_p (bb, &visited)
1046 || bb == loop->header)
1048 /* This block is now visited. */
1049 bitmap_set_bit (visited, bb->index);
1050 blocks[visited_count++] = bb;
1054 if (index == loop->num_nodes
1055 && visited_count != loop->num_nodes)
1061 free (blocks_in_bfs_order);
1062 BITMAP_FREE (visited);
1066 /* Return true if one of the basic block BB edge is exit of LOOP. */
1069 bb_with_exit_edge_p (struct loop *loop, basic_block bb)
1073 bool exit_edge_found = false;
1075 FOR_EACH_EDGE (e, ei, bb->succs)
1076 if (loop_exit_edge_p (loop, e))
1078 exit_edge_found = true;
1082 return exit_edge_found;
1085 /* Tree if-conversion pass management. */
1088 main_tree_if_conversion (void)
1090 unsigned i, loop_num;
1096 loop_num = current_loops->num;
1097 for (i = 0; i < loop_num; i++)
1099 loop = current_loops->parray[i];
1103 tree_if_conversion (loop, true);
1109 gate_tree_if_conversion (void)
1111 return flag_tree_vectorize != 0;
1114 struct tree_opt_pass pass_if_conversion =
1117 gate_tree_if_conversion, /* gate */
1118 main_tree_if_conversion, /* execute */
1121 0, /* static_pass_number */
1123 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
1124 0, /* properties_provided */
1125 0, /* properties_destroyed */
1126 TODO_dump_func, /* todo_flags_start */
1130 | TODO_verify_flow, /* todo_flags_finish */