1 /* If-conversion for vectorizer.
2 Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
4 Contributed by Devang Patel <dpatel@apple.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* This pass implements a tree level if-conversion of loops. Its
23 initial goal is to help the vectorizer to vectorize loops with
26 A short description of if-conversion:
28 o Decide if a loop is if-convertible or not.
29 o Walk all loop basic blocks in breadth first order (BFS order).
30 o Remove conditional statements (at the end of basic block)
31 and propagate condition into destination basic blocks'
33 o Replace modify expression with conditional modify expression
34 using current basic block's condition.
35 o Merge all basic blocks
36 o Replace phi nodes with conditional modify expr
37 o Merge all basic blocks into header
39 Sample transformation:
44 # i_23 = PHI <0(0), i_18(10)>;
47 if (j_15 > 41) goto <L1>; else goto <L17>;
54 # iftmp.2_4 = PHI <0(8), 42(2)>;
58 if (i_18 <= 15) goto <L19>; else goto <L18>;
68 # i_23 = PHI <0(0), i_18(10)>;
73 iftmp.2_4 = j_15 > 41 ? 42 : 0;
76 if (i_18 <= 15) goto <L19>; else goto <L18>;
86 #include "coretypes.h"
91 #include "basic-block.h"
92 #include "tree-pretty-print.h"
93 #include "gimple-pretty-print.h"
94 #include "tree-flow.h"
95 #include "tree-dump.h"
97 #include "tree-chrec.h"
98 #include "tree-data-ref.h"
99 #include "tree-scalar-evolution.h"
100 #include "tree-pass.h"
102 /* List of basic blocks in if-conversion-suitable order. */
103 static basic_block *ifc_bbs;
105 /* Create a new temp variable of type TYPE. Add GIMPLE_ASSIGN to assign EXP
106 to the new variable. */
109 ifc_temp_var (tree type, tree exp)
111 const char *name = "_ifc_";
115 /* Create new temporary variable. */
116 var = create_tmp_var (type, name);
117 add_referenced_var (var);
119 /* Build new statement to assign EXP to new variable. */
120 stmt = gimple_build_assign (var, exp);
122 /* Get SSA name for the new variable and set make new statement
123 its definition statement. */
124 new_name = make_ssa_name (var, stmt);
125 gimple_assign_set_lhs (stmt, new_name);
126 SSA_NAME_DEF_STMT (new_name) = stmt;
132 /* Return true when COND is a true predicate. */
135 is_true_predicate (tree cond)
137 return (cond == NULL_TREE
138 || cond == boolean_true_node
139 || integer_onep (cond));
142 /* Returns true when BB has a predicate that is not trivial: true or
146 is_predicated (basic_block bb)
148 return !is_true_predicate ((tree) bb->aux);
151 /* Add condition NEW_COND to the predicate list of basic block BB. */
154 add_to_predicate_list (basic_block bb, tree new_cond)
156 tree cond = (tree) bb->aux;
158 bb->aux = is_true_predicate (cond) ? new_cond :
159 fold_build2_loc (EXPR_LOCATION (cond),
160 TRUTH_OR_EXPR, boolean_type_node,
164 /* Add the condition COND to the previous condition PREV_COND, and add
165 this to the predicate list of the destination of edge E. LOOP is
166 the loop to be if-converted. */
169 add_to_dst_predicate_list (struct loop *loop, edge e,
170 tree prev_cond, tree cond)
172 if (!flow_bb_inside_loop_p (loop, e->dest))
175 if (!is_true_predicate (prev_cond))
176 cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
179 add_to_predicate_list (e->dest, cond);
182 /* Return true if one of the successor edges of BB exits LOOP. */
185 bb_with_exit_edge_p (struct loop *loop, basic_block bb)
190 FOR_EACH_EDGE (e, ei, bb->succs)
191 if (loop_exit_edge_p (loop, e))
197 /* Return true when PHI is if-convertible. PHI is part of loop LOOP
198 and it belongs to basic block BB.
200 PHI is not if-convertible if:
201 - it has more than 2 arguments,
202 - virtual PHI is immediately used in another PHI node,
203 - virtual PHI on BB other than header. */
206 if_convertible_phi_p (struct loop *loop, basic_block bb, gimple phi)
208 if (dump_file && (dump_flags & TDF_DETAILS))
210 fprintf (dump_file, "-------------------------\n");
211 print_gimple_stmt (dump_file, phi, 0, TDF_SLIM);
214 if (bb != loop->header && gimple_phi_num_args (phi) != 2)
216 if (dump_file && (dump_flags & TDF_DETAILS))
217 fprintf (dump_file, "More than two phi node args.\n");
221 if (!is_gimple_reg (SSA_NAME_VAR (gimple_phi_result (phi))))
223 imm_use_iterator imm_iter;
226 if (bb != loop->header)
228 if (dump_file && (dump_flags & TDF_DETAILS))
229 fprintf (dump_file, "Virtual phi not on loop header.\n");
232 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_phi_result (phi))
234 if (gimple_code (USE_STMT (use_p)) == GIMPLE_PHI)
236 if (dump_file && (dump_flags & TDF_DETAILS))
237 fprintf (dump_file, "Difficult to handle this virtual phi.\n");
246 /* Return true when STMT is if-convertible.
248 GIMPLE_ASSIGN statement is not if-convertible if,
251 - LHS is not var decl.
253 GIMPLE_ASSIGN is part of block BB, which is inside loop LOOP. */
256 if_convertible_gimple_assign_stmt_p (struct loop *loop, basic_block bb,
259 tree lhs = gimple_assign_lhs (stmt);
261 if (dump_file && (dump_flags & TDF_DETAILS))
263 fprintf (dump_file, "-------------------------\n");
264 print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
267 /* Some of these constrains might be too conservative. */
268 if (stmt_ends_bb_p (stmt)
269 || gimple_has_volatile_ops (stmt)
270 || (TREE_CODE (lhs) == SSA_NAME
271 && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
272 || gimple_has_side_effects (stmt))
274 if (dump_file && (dump_flags & TDF_DETAILS))
275 fprintf (dump_file, "stmt not suitable for ifcvt\n");
279 if (gimple_assign_rhs_could_trap_p (stmt))
281 if (dump_file && (dump_flags & TDF_DETAILS))
282 fprintf (dump_file, "tree could trap...\n");
286 if (TREE_CODE (lhs) != SSA_NAME
287 && bb != loop->header
288 && !bb_with_exit_edge_p (loop, bb))
290 if (dump_file && (dump_flags & TDF_DETAILS))
292 fprintf (dump_file, "LHS is not var\n");
293 print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
301 /* Return true when STMT is if-convertible.
303 A statement is if-convertible if:
304 - it is an if-convertible GIMPLE_ASSGIN,
305 - it is a GIMPLE_LABEL or a GIMPLE_COND.
307 STMT is inside BB, which is inside loop LOOP. */
310 if_convertible_stmt_p (struct loop *loop, basic_block bb, gimple stmt)
312 switch (gimple_code (stmt))
320 return if_convertible_gimple_assign_stmt_p (loop, bb, stmt);
323 /* Don't know what to do with 'em so don't do anything. */
324 if (dump_file && (dump_flags & TDF_DETAILS))
326 fprintf (dump_file, "don't know what to do\n");
327 print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
336 /* Return true when BB is if-convertible. This routine does not check
337 basic block's statements and phis.
339 A basic block is not if-convertible if:
340 - it is non-empty and it is after the exit block (in BFS order),
341 - it is after the exit block but before the latch,
342 - its edges are not normal.
344 EXIT_BB is the basic block containing the exit of the LOOP. BB is
348 if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
353 if (dump_file && (dump_flags & TDF_DETAILS))
354 fprintf (dump_file, "----------[%d]-------------\n", bb->index);
356 if (EDGE_COUNT (bb->preds) > 2
357 || EDGE_COUNT (bb->succs) > 2)
362 if (bb != loop->latch)
364 if (dump_file && (dump_flags & TDF_DETAILS))
365 fprintf (dump_file, "basic block after exit bb but before latch\n");
368 else if (!empty_block_p (bb))
370 if (dump_file && (dump_flags & TDF_DETAILS))
371 fprintf (dump_file, "non empty basic block after exit bb\n");
374 else if (bb == loop->latch
376 && !dominated_by_p (CDI_DOMINATORS, bb, exit_bb))
378 if (dump_file && (dump_flags & TDF_DETAILS))
379 fprintf (dump_file, "latch is not dominated by exit_block\n");
384 /* Be less adventurous and handle only normal edges. */
385 FOR_EACH_EDGE (e, ei, bb->succs)
387 (EDGE_ABNORMAL_CALL | EDGE_EH | EDGE_ABNORMAL | EDGE_IRREDUCIBLE_LOOP))
389 if (dump_file && (dump_flags & TDF_DETAILS))
390 fprintf (dump_file, "Difficult to handle edges\n");
397 /* Return true when all predecessor blocks of BB are visited. The
398 VISITED bitmap keeps track of the visited blocks. */
401 pred_blocks_visited_p (basic_block bb, bitmap *visited)
405 FOR_EACH_EDGE (e, ei, bb->preds)
406 if (!bitmap_bit_p (*visited, e->src->index))
412 /* Get body of a LOOP in suitable order for if-conversion. It is
413 caller's responsibility to deallocate basic block list.
414 If-conversion suitable order is, breadth first sort (BFS) order
415 with an additional constraint: select a block only if all its
416 predecessors are already selected. */
419 get_loop_body_in_if_conv_order (const struct loop *loop)
421 basic_block *blocks, *blocks_in_bfs_order;
424 unsigned int index = 0;
425 unsigned int visited_count = 0;
427 gcc_assert (loop->num_nodes);
428 gcc_assert (loop->latch != EXIT_BLOCK_PTR);
430 blocks = XCNEWVEC (basic_block, loop->num_nodes);
431 visited = BITMAP_ALLOC (NULL);
433 blocks_in_bfs_order = get_loop_body_in_bfs_order (loop);
436 while (index < loop->num_nodes)
438 bb = blocks_in_bfs_order [index];
440 if (bb->flags & BB_IRREDUCIBLE_LOOP)
442 free (blocks_in_bfs_order);
443 BITMAP_FREE (visited);
448 if (!bitmap_bit_p (visited, bb->index))
450 if (pred_blocks_visited_p (bb, &visited)
451 || bb == loop->header)
453 /* This block is now visited. */
454 bitmap_set_bit (visited, bb->index);
455 blocks[visited_count++] = bb;
461 if (index == loop->num_nodes
462 && visited_count != loop->num_nodes)
466 free (blocks_in_bfs_order);
467 BITMAP_FREE (visited);
471 /* Returns true when the analysis of the predicates for all the basic
472 blocks in LOOP succeeded.
474 predicate_bbs first clears the ->aux fields of the basic blocks.
475 These fields are then initialized with the tree expressions
476 representing the predicates under which a basic block is executed
477 in the LOOP. As the loop->header is executed at each iteration, it
478 has the "true" predicate. Other statements executed under a
479 condition are predicated with that condition, for example
486 S1 will be predicated with "x", and S2 will be predicated with
490 predicate_bbs (loop_p loop)
494 for (i = 0; i < loop->num_nodes; i++)
495 ifc_bbs[i]->aux = NULL;
497 for (i = 0; i < loop->num_nodes; i++)
499 basic_block bb = ifc_bbs [i];
500 tree cond = (tree) bb->aux;
501 gimple_stmt_iterator itr;
503 for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
505 gimple stmt = gsi_stmt (itr);
507 switch (gimple_code (stmt))
515 /* ??? Should there be conditional GIMPLE_DEBUG_BINDs? */
516 if (gimple_debug_bind_p (gsi_stmt (itr)))
518 gimple_debug_bind_reset_value (gsi_stmt (itr));
519 update_stmt (gsi_stmt (itr));
526 edge true_edge, false_edge;
527 location_t loc = gimple_location (stmt);
528 tree c = fold_build2_loc (loc, gimple_cond_code (stmt),
530 gimple_cond_lhs (stmt),
531 gimple_cond_rhs (stmt));
533 extract_true_false_edges_from_block (gimple_bb (stmt),
534 &true_edge, &false_edge);
536 /* Add new condition into destination's predicate list. */
538 /* If C is true, then TRUE_EDGE is taken. */
539 add_to_dst_predicate_list (loop, true_edge, cond, c);
541 /* If C is false, then FALSE_EDGE is taken. */
542 c2 = invert_truthvalue_loc (loc, unshare_expr (c));
543 add_to_dst_predicate_list (loop, false_edge, cond, c2);
550 /* Not handled yet in if-conversion. */
558 /* If current bb has only one successor, then consider it as an
559 unconditional goto. */
560 if (single_succ_p (bb))
562 basic_block bb_n = single_succ (bb);
564 /* The successor bb inherits the predicate of its
565 predecessor. If there is no predicate in the predecessor
566 bb, then consider the successor bb as always executed. */
567 if (cond == NULL_TREE)
568 cond = boolean_true_node;
570 add_to_predicate_list (bb_n, cond);
574 /* The loop header is always executed. */
575 loop->header->aux = boolean_true_node;
580 /* Return true when LOOP is if-convertible.
581 LOOP is if-convertible if:
583 - it has two or more basic blocks,
584 - it has only one exit,
585 - loop header is not the exit edge,
586 - if its basic blocks and phi nodes are if convertible. */
589 if_convertible_loop_p (struct loop *loop)
594 basic_block exit_bb = NULL;
596 /* Handle only innermost loop. */
597 if (!loop || loop->inner)
599 if (dump_file && (dump_flags & TDF_DETAILS))
600 fprintf (dump_file, "not innermost loop\n");
604 /* If only one block, no need for if-conversion. */
605 if (loop->num_nodes <= 2)
607 if (dump_file && (dump_flags & TDF_DETAILS))
608 fprintf (dump_file, "less than 2 basic blocks\n");
612 /* More than one loop exit is too much to handle. */
613 if (!single_exit (loop))
615 if (dump_file && (dump_flags & TDF_DETAILS))
616 fprintf (dump_file, "multiple exits\n");
620 /* ??? Check target's vector conditional operation support for vectorizer. */
622 /* If one of the loop header's edge is exit edge then do not apply
624 FOR_EACH_EDGE (e, ei, loop->header->succs)
626 if (loop_exit_edge_p (loop, e))
630 /* Don't if-convert the loop when the data dependences cannot be
631 computed: the loop won't be vectorized in that case. */
633 VEC (data_reference_p, heap) *refs = VEC_alloc (data_reference_p, heap, 5);
634 VEC (ddr_p, heap) *ddrs = VEC_alloc (ddr_p, heap, 25);
635 bool res = compute_data_dependences_for_loop (loop, true, &refs, &ddrs);
637 free_data_refs (refs);
638 free_dependence_relations (ddrs);
644 calculate_dominance_info (CDI_DOMINATORS);
646 /* Allow statements that can be handled during if-conversion. */
647 ifc_bbs = get_loop_body_in_if_conv_order (loop);
650 if (dump_file && (dump_flags & TDF_DETAILS))
651 fprintf (dump_file, "Irreducible loop\n");
655 for (i = 0; i < loop->num_nodes; i++)
657 basic_block bb = ifc_bbs[i];
659 if (!if_convertible_bb_p (loop, bb, exit_bb))
662 if (bb_with_exit_edge_p (loop, bb))
666 if (!predicate_bbs (loop))
669 for (i = 0; i < loop->num_nodes; i++)
671 basic_block bb = ifc_bbs[i];
672 gimple_stmt_iterator itr;
674 for (itr = gsi_start_phis (bb); !gsi_end_p (itr); gsi_next (&itr))
675 if (!if_convertible_phi_p (loop, bb, gsi_stmt (itr)))
678 /* For non predicated BBs, don't check their statements. */
679 if (!is_predicated (bb))
682 for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
683 if (!if_convertible_stmt_p (loop, bb, gsi_stmt (itr)))
688 fprintf (dump_file, "Applying if-conversion\n");
693 /* During if-conversion, the bb->aux field is used to hold a predicate
694 list. This function cleans for all the basic blocks in the given
695 LOOP their predicate list. */
698 clean_predicate_lists (struct loop *loop)
701 basic_block *bbs = get_loop_body (loop);
703 for (i = 0; i < loop->num_nodes; i++)
709 /* Basic block BB has two predecessors. Using predecessor's bb->aux
710 field, set appropriate condition COND for the PHI node replacement.
711 Return true block whose phi arguments are selected when cond is
712 true. LOOP is the loop containing the if-converted region, GSI is
713 the place to insert the code for the if-conversion. */
716 find_phi_replacement_condition (struct loop *loop,
717 basic_block bb, tree *cond,
718 gimple_stmt_iterator *gsi)
720 edge first_edge, second_edge;
723 gcc_assert (EDGE_COUNT (bb->preds) == 2);
724 first_edge = EDGE_PRED (bb, 0);
725 second_edge = EDGE_PRED (bb, 1);
727 /* Use condition based on following criteria:
733 S2 is preferred over S1. Make 'b' first_bb and use its condition.
735 2) Do not make loop header first_bb.
738 S1: x = !(c == d)? a : b;
743 S3: x = (c == d) ? b : a;
745 S3 is preferred over S1 and S2*, Make 'b' first_bb and use
748 4) If pred B is dominated by pred A then use pred B's condition.
751 /* Select condition that is not TRUTH_NOT_EXPR. */
752 tmp_cond = (tree) (first_edge->src)->aux;
753 gcc_assert (tmp_cond);
755 if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
759 tmp_edge = first_edge;
760 first_edge = second_edge;
761 second_edge = tmp_edge;
764 /* Check if FIRST_BB is loop header or not and make sure that
765 FIRST_BB does not dominate SECOND_BB. */
766 if (first_edge->src == loop->header
767 || dominated_by_p (CDI_DOMINATORS,
768 second_edge->src, first_edge->src))
770 *cond = (tree) (second_edge->src)->aux;
772 if (TREE_CODE (*cond) == TRUTH_NOT_EXPR)
773 *cond = invert_truthvalue (*cond);
775 /* Select non loop header bb. */
776 first_edge = second_edge;
779 *cond = (tree) (first_edge->src)->aux;
781 /* Gimplify the condition: the vectorizer prefers to have gimple
782 values as conditions. Various targets use different means to
783 communicate conditions in vector compare operations. Using a
784 gimple value allows the compiler to emit vector compare and
785 select RTL without exposing compare's result. */
786 *cond = force_gimple_operand_gsi (gsi, unshare_expr (*cond),
788 true, GSI_SAME_STMT);
789 if (!is_gimple_reg (*cond) && !is_gimple_condexpr (*cond))
793 new_stmt = ifc_temp_var (TREE_TYPE (*cond), unshare_expr (*cond));
794 gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
795 *cond = gimple_assign_lhs (new_stmt);
800 return first_edge->src;
803 /* Replace PHI node with conditional modify expr using COND. This
804 routine does not handle PHI nodes with more than two arguments.
807 S1: A = PHI <x1(1), x2(5)
809 S2: A = cond ? x1 : x2;
811 The generated code is inserted at GSI that points to the top of
812 basic block's statement list. When COND is true, phi arg from
813 TRUE_BB is selected. */
816 replace_phi_with_cond_gimple_assign_stmt (gimple phi, tree cond,
818 gimple_stmt_iterator *gsi)
825 gcc_assert (gimple_code (phi) == GIMPLE_PHI
826 && gimple_phi_num_args (phi) == 2);
828 bb = gimple_bb (phi);
830 arg = degenerate_phi_result (phi);
836 /* Use condition that is not TRUTH_NOT_EXPR in conditional modify expr. */
837 if (EDGE_PRED (bb, 1)->src == true_bb)
839 arg_0 = gimple_phi_arg_def (phi, 1);
840 arg_1 = gimple_phi_arg_def (phi, 0);
844 arg_0 = gimple_phi_arg_def (phi, 0);
845 arg_1 = gimple_phi_arg_def (phi, 1);
848 /* Build new RHS using selected condition and arguments. */
849 rhs = build3 (COND_EXPR, TREE_TYPE (PHI_RESULT (phi)),
850 unshare_expr (cond), arg_0, arg_1);
853 new_stmt = gimple_build_assign (PHI_RESULT (phi), rhs);
854 SSA_NAME_DEF_STMT (gimple_phi_result (phi)) = new_stmt;
855 gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
856 update_stmt (new_stmt);
858 if (dump_file && (dump_flags & TDF_DETAILS))
860 fprintf (dump_file, "new phi replacement stmt\n");
861 print_gimple_stmt (dump_file, new_stmt, 0, TDF_SLIM);
865 /* Process phi nodes for the given LOOP. Replace phi nodes with
866 conditional modify expressions. */
869 process_phi_nodes (struct loop *loop)
872 unsigned int orig_loop_num_nodes = loop->num_nodes;
875 for (i = 1; i < orig_loop_num_nodes; i++)
878 tree cond = NULL_TREE;
879 gimple_stmt_iterator gsi, phi_gsi;
880 basic_block true_bb = NULL;
883 if (bb == loop->header)
886 phi_gsi = gsi_start_phis (bb);
887 gsi = gsi_after_labels (bb);
889 /* BB has two predecessors. Using predecessor's aux field, set
890 appropriate condition for the PHI node replacement. */
891 if (!gsi_end_p (phi_gsi))
892 true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
894 while (!gsi_end_p (phi_gsi))
896 phi = gsi_stmt (phi_gsi);
897 replace_phi_with_cond_gimple_assign_stmt (phi, cond, true_bb, &gsi);
898 release_phi_node (phi);
901 set_phi_nodes (bb, NULL);
905 /* Remove all GIMPLE_CONDs and GIMPLE_LABELs of all the basic blocks
906 other than the exit and latch of the LOOP. */
909 remove_conditions_and_labels (loop_p loop)
911 gimple_stmt_iterator gsi;
914 for (i = 0; i < loop->num_nodes; i++)
916 basic_block bb = ifc_bbs [i];
918 if (bb_with_exit_edge_p (loop, bb)
919 || bb == loop->latch)
922 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
923 if (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND
924 || gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL)
925 gsi_remove (&gsi, true);
931 /* Combine all the basic blocks from LOOP into one or two super basic
932 blocks. Replace PHI nodes with conditional modify expressions. */
935 combine_blocks (struct loop *loop)
937 basic_block bb, exit_bb, merge_target_bb;
938 unsigned int orig_loop_num_nodes = loop->num_nodes;
943 remove_conditions_and_labels (loop);
945 /* Process phi nodes to prepare blocks for merge. */
946 process_phi_nodes (loop);
948 /* Merge basic blocks: first remove all the edges in the loop,
949 except for those from the exit block. */
951 for (i = 0; i < orig_loop_num_nodes; i++)
954 if (bb_with_exit_edge_p (loop, bb))
960 gcc_assert (exit_bb != loop->latch);
962 for (i = 1; i < orig_loop_num_nodes; i++)
966 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei));)
968 if (e->src == exit_bb)
977 if (exit_bb != loop->header)
979 /* Connect this node to loop header. */
980 make_edge (loop->header, exit_bb, EDGE_FALLTHRU);
981 set_immediate_dominator (CDI_DOMINATORS, exit_bb, loop->header);
984 /* Redirect non-exit edges to loop->latch. */
985 FOR_EACH_EDGE (e, ei, exit_bb->succs)
987 if (!loop_exit_edge_p (loop, e))
988 redirect_edge_and_branch (e, loop->latch);
990 set_immediate_dominator (CDI_DOMINATORS, loop->latch, exit_bb);
994 /* If the loop does not have an exit, reconnect header and latch. */
995 make_edge (loop->header, loop->latch, EDGE_FALLTHRU);
996 set_immediate_dominator (CDI_DOMINATORS, loop->latch, loop->header);
999 merge_target_bb = loop->header;
1000 for (i = 1; i < orig_loop_num_nodes; i++)
1002 gimple_stmt_iterator gsi;
1003 gimple_stmt_iterator last;
1007 if (bb == exit_bb || bb == loop->latch)
1010 /* Make stmts member of loop->header. */
1011 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1012 gimple_set_bb (gsi_stmt (gsi), merge_target_bb);
1014 /* Update stmt list. */
1015 last = gsi_last_bb (merge_target_bb);
1016 gsi_insert_seq_after (&last, bb_seq (bb), GSI_NEW_STMT);
1017 set_bb_seq (bb, NULL);
1019 delete_basic_block (bb);
1022 /* If possible, merge loop header to the block with the exit edge.
1023 This reduces the number of basic blocks to two, to please the
1024 vectorizer that handles only loops with two nodes.
1026 FIXME: Call cleanup_tree_cfg. */
1028 && exit_bb != loop->header
1029 && can_merge_blocks_p (loop->header, exit_bb))
1030 merge_blocks (loop->header, exit_bb);
1033 /* If-convert LOOP when it is legal. For the moment this pass has no
1034 profitability analysis. */
1037 tree_if_conversion (struct loop *loop)
1041 if (!if_convertible_loop_p (loop))
1044 /* Now all statements are if-convertible. Combine all the basic
1045 blocks into one huge basic block doing the if-conversion
1047 combine_blocks (loop);
1050 clean_predicate_lists (loop);
1058 /* Tree if-conversion pass management. */
1061 main_tree_if_conversion (void)
1066 if (number_of_loops () <= 1)
1069 FOR_EACH_LOOP (li, loop, 0)
1070 tree_if_conversion (loop);
1076 gate_tree_if_conversion (void)
1078 return flag_tree_vectorize != 0;
1081 struct gimple_opt_pass pass_if_conversion =
1086 gate_tree_if_conversion, /* gate */
1087 main_tree_if_conversion, /* execute */
1090 0, /* static_pass_number */
1091 TV_NONE, /* tv_id */
1092 PROP_cfg | PROP_ssa, /* properties_required */
1093 0, /* properties_provided */
1094 0, /* properties_destroyed */
1095 0, /* todo_flags_start */
1096 TODO_dump_func | TODO_verify_stmts | TODO_verify_flow
1097 /* todo_flags_finish */