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
487 S2 will be predicated with "!x". */
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))
518 edge true_edge, false_edge;
519 location_t loc = gimple_location (stmt);
520 tree c = fold_build2_loc (loc, gimple_cond_code (stmt),
522 gimple_cond_lhs (stmt),
523 gimple_cond_rhs (stmt));
525 extract_true_false_edges_from_block (gimple_bb (stmt),
526 &true_edge, &false_edge);
528 /* Add new condition into destination's predicate list. */
530 /* If C is true, then TRUE_EDGE is taken. */
531 add_to_dst_predicate_list (loop, true_edge, cond, c);
533 /* If C is false, then FALSE_EDGE is taken. */
534 c2 = invert_truthvalue_loc (loc, unshare_expr (c));
535 add_to_dst_predicate_list (loop, false_edge, cond, c2);
542 /* Not handled yet in if-conversion. */
547 /* If current bb has only one successor, then consider it as an
548 unconditional goto. */
549 if (single_succ_p (bb))
551 basic_block bb_n = single_succ (bb);
553 /* The successor bb inherits the predicate of its
554 predecessor. If there is no predicate in the predecessor
555 bb, then consider the successor bb as always executed. */
556 if (cond == NULL_TREE)
557 cond = boolean_true_node;
559 add_to_predicate_list (bb_n, cond);
563 /* The loop header is always executed. */
564 loop->header->aux = boolean_true_node;
569 /* Return true when LOOP is if-convertible.
570 LOOP is if-convertible if:
572 - it has two or more basic blocks,
573 - it has only one exit,
574 - loop header is not the exit edge,
575 - if its basic blocks and phi nodes are if convertible. */
578 if_convertible_loop_p (struct loop *loop)
583 basic_block exit_bb = NULL;
585 /* Handle only innermost loop. */
586 if (!loop || loop->inner)
588 if (dump_file && (dump_flags & TDF_DETAILS))
589 fprintf (dump_file, "not innermost loop\n");
593 /* If only one block, no need for if-conversion. */
594 if (loop->num_nodes <= 2)
596 if (dump_file && (dump_flags & TDF_DETAILS))
597 fprintf (dump_file, "less than 2 basic blocks\n");
601 /* More than one loop exit is too much to handle. */
602 if (!single_exit (loop))
604 if (dump_file && (dump_flags & TDF_DETAILS))
605 fprintf (dump_file, "multiple exits\n");
609 /* ??? Check target's vector conditional operation support for vectorizer. */
611 /* If one of the loop header's edge is exit edge then do not apply
613 FOR_EACH_EDGE (e, ei, loop->header->succs)
615 if (loop_exit_edge_p (loop, e))
619 /* Don't if-convert the loop when the data dependences cannot be
620 computed: the loop won't be vectorized in that case. */
622 VEC (data_reference_p, heap) *refs = VEC_alloc (data_reference_p, heap, 5);
623 VEC (ddr_p, heap) *ddrs = VEC_alloc (ddr_p, heap, 25);
624 bool res = compute_data_dependences_for_loop (loop, true, &refs, &ddrs);
626 free_data_refs (refs);
627 free_dependence_relations (ddrs);
633 calculate_dominance_info (CDI_DOMINATORS);
635 /* Allow statements that can be handled during if-conversion. */
636 ifc_bbs = get_loop_body_in_if_conv_order (loop);
639 if (dump_file && (dump_flags & TDF_DETAILS))
640 fprintf (dump_file, "Irreducible loop\n");
644 for (i = 0; i < loop->num_nodes; i++)
646 basic_block bb = ifc_bbs[i];
648 if (!if_convertible_bb_p (loop, bb, exit_bb))
651 if (bb_with_exit_edge_p (loop, bb))
655 if (!predicate_bbs (loop))
658 for (i = 0; i < loop->num_nodes; i++)
660 basic_block bb = ifc_bbs[i];
661 gimple_stmt_iterator itr;
663 for (itr = gsi_start_phis (bb); !gsi_end_p (itr); gsi_next (&itr))
664 if (!if_convertible_phi_p (loop, bb, gsi_stmt (itr)))
667 /* For non predicated BBs, don't check their statements. */
668 if (!is_predicated (bb))
671 for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
672 if (!if_convertible_stmt_p (loop, bb, gsi_stmt (itr)))
677 fprintf (dump_file, "Applying if-conversion\n");
682 /* During if-conversion, the bb->aux field is used to hold a predicate
683 list. This function cleans for all the basic blocks in the given
684 LOOP their predicate list. */
687 clean_predicate_lists (struct loop *loop)
690 basic_block *bbs = get_loop_body (loop);
692 for (i = 0; i < loop->num_nodes; i++)
698 /* Basic block BB has two predecessors. Using predecessor's bb->aux
699 field, set appropriate condition COND for the PHI node replacement.
700 Return true block whose phi arguments are selected when cond is
701 true. LOOP is the loop containing the if-converted region, GSI is
702 the place to insert the code for the if-conversion. */
705 find_phi_replacement_condition (struct loop *loop,
706 basic_block bb, tree *cond,
707 gimple_stmt_iterator *gsi)
709 edge first_edge, second_edge;
712 gcc_assert (EDGE_COUNT (bb->preds) == 2);
713 first_edge = EDGE_PRED (bb, 0);
714 second_edge = EDGE_PRED (bb, 1);
716 /* Use condition based on following criteria:
722 S2 is preferred over S1. Make 'b' first_bb and use its condition.
724 2) Do not make loop header first_bb.
727 S1: x = !(c == d)? a : b;
732 S3: x = (c == d) ? b : a;
734 S3 is preferred over S1 and S2*, Make 'b' first_bb and use
737 4) If pred B is dominated by pred A then use pred B's condition.
740 /* Select condition that is not TRUTH_NOT_EXPR. */
741 tmp_cond = (tree) (first_edge->src)->aux;
742 gcc_assert (tmp_cond);
744 if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
748 tmp_edge = first_edge;
749 first_edge = second_edge;
750 second_edge = tmp_edge;
753 /* Check if FIRST_BB is loop header or not and make sure that
754 FIRST_BB does not dominate SECOND_BB. */
755 if (first_edge->src == loop->header
756 || dominated_by_p (CDI_DOMINATORS,
757 second_edge->src, first_edge->src))
759 *cond = (tree) (second_edge->src)->aux;
761 if (TREE_CODE (*cond) == TRUTH_NOT_EXPR)
762 *cond = invert_truthvalue (*cond);
764 /* Select non loop header bb. */
765 first_edge = second_edge;
768 *cond = (tree) (first_edge->src)->aux;
770 /* Gimplify the condition: the vectorizer prefers to have gimple
771 values as conditions. Various targets use different means to
772 communicate conditions in vector compare operations. Using a
773 gimple value allows the compiler to emit vector compare and
774 select RTL without exposing compare's result. */
775 *cond = force_gimple_operand_gsi (gsi, unshare_expr (*cond),
777 true, GSI_SAME_STMT);
778 if (!is_gimple_reg (*cond) && !is_gimple_condexpr (*cond))
782 new_stmt = ifc_temp_var (TREE_TYPE (*cond), unshare_expr (*cond));
783 gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
784 *cond = gimple_assign_lhs (new_stmt);
789 return first_edge->src;
792 /* Replace PHI node with conditional modify expr using COND. This
793 routine does not handle PHI nodes with more than two arguments.
796 S1: A = PHI <x1(1), x2(5)
798 S2: A = cond ? x1 : x2;
800 The generated code is inserted at GSI that points to the top of
801 basic block's statement list. When COND is true, phi arg from
802 TRUE_BB is selected. */
805 replace_phi_with_cond_gimple_assign_stmt (gimple phi, tree cond,
807 gimple_stmt_iterator *gsi)
814 gcc_assert (gimple_code (phi) == GIMPLE_PHI
815 && gimple_phi_num_args (phi) == 2);
817 bb = gimple_bb (phi);
819 arg = degenerate_phi_result (phi);
825 /* Use condition that is not TRUTH_NOT_EXPR in conditional modify expr. */
826 if (EDGE_PRED (bb, 1)->src == true_bb)
828 arg_0 = gimple_phi_arg_def (phi, 1);
829 arg_1 = gimple_phi_arg_def (phi, 0);
833 arg_0 = gimple_phi_arg_def (phi, 0);
834 arg_1 = gimple_phi_arg_def (phi, 1);
837 /* Build new RHS using selected condition and arguments. */
838 rhs = build3 (COND_EXPR, TREE_TYPE (PHI_RESULT (phi)),
839 unshare_expr (cond), arg_0, arg_1);
842 new_stmt = gimple_build_assign (PHI_RESULT (phi), rhs);
843 SSA_NAME_DEF_STMT (gimple_phi_result (phi)) = new_stmt;
844 gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
845 update_stmt (new_stmt);
847 if (dump_file && (dump_flags & TDF_DETAILS))
849 fprintf (dump_file, "new phi replacement stmt\n");
850 print_gimple_stmt (dump_file, new_stmt, 0, TDF_SLIM);
854 /* Process phi nodes for the given LOOP. Replace phi nodes with
855 conditional modify expressions. */
858 process_phi_nodes (struct loop *loop)
861 unsigned int orig_loop_num_nodes = loop->num_nodes;
864 for (i = 1; i < orig_loop_num_nodes; i++)
867 tree cond = NULL_TREE;
868 gimple_stmt_iterator gsi, phi_gsi;
869 basic_block true_bb = NULL;
872 if (bb == loop->header)
875 phi_gsi = gsi_start_phis (bb);
876 gsi = gsi_after_labels (bb);
878 /* BB has two predecessors. Using predecessor's aux field, set
879 appropriate condition for the PHI node replacement. */
880 if (!gsi_end_p (phi_gsi))
881 true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
883 while (!gsi_end_p (phi_gsi))
885 phi = gsi_stmt (phi_gsi);
886 replace_phi_with_cond_gimple_assign_stmt (phi, cond, true_bb, &gsi);
887 release_phi_node (phi);
890 set_phi_nodes (bb, NULL);
894 /* Remove all GIMPLE_CONDs and GIMPLE_LABELs of all the basic blocks
895 other than the exit and latch of the LOOP. Also resets the
896 GIMPLE_DEBUG information. */
899 remove_conditions_and_labels (loop_p loop)
901 gimple_stmt_iterator gsi;
904 for (i = 0; i < loop->num_nodes; i++)
906 basic_block bb = ifc_bbs [i];
908 if (bb_with_exit_edge_p (loop, bb)
909 || bb == loop->latch)
912 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
913 switch (gimple_code (gsi_stmt (gsi)))
917 gsi_remove (&gsi, true);
921 /* ??? Should there be conditional GIMPLE_DEBUG_BINDs? */
922 if (gimple_debug_bind_p (gsi_stmt (gsi)))
924 gimple_debug_bind_reset_value (gsi_stmt (gsi));
925 update_stmt (gsi_stmt (gsi));
936 /* Combine all the basic blocks from LOOP into one or two super basic
937 blocks. Replace PHI nodes with conditional modify expressions. */
940 combine_blocks (struct loop *loop)
942 basic_block bb, exit_bb, merge_target_bb;
943 unsigned int orig_loop_num_nodes = loop->num_nodes;
948 remove_conditions_and_labels (loop);
950 /* Process phi nodes to prepare blocks for merge. */
951 process_phi_nodes (loop);
953 /* Merge basic blocks: first remove all the edges in the loop,
954 except for those from the exit block. */
956 for (i = 0; i < orig_loop_num_nodes; i++)
959 if (bb_with_exit_edge_p (loop, bb))
965 gcc_assert (exit_bb != loop->latch);
967 for (i = 1; i < orig_loop_num_nodes; i++)
971 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei));)
973 if (e->src == exit_bb)
982 if (exit_bb != loop->header)
984 /* Connect this node to loop header. */
985 make_edge (loop->header, exit_bb, EDGE_FALLTHRU);
986 set_immediate_dominator (CDI_DOMINATORS, exit_bb, loop->header);
989 /* Redirect non-exit edges to loop->latch. */
990 FOR_EACH_EDGE (e, ei, exit_bb->succs)
992 if (!loop_exit_edge_p (loop, e))
993 redirect_edge_and_branch (e, loop->latch);
995 set_immediate_dominator (CDI_DOMINATORS, loop->latch, exit_bb);
999 /* If the loop does not have an exit, reconnect header and latch. */
1000 make_edge (loop->header, loop->latch, EDGE_FALLTHRU);
1001 set_immediate_dominator (CDI_DOMINATORS, loop->latch, loop->header);
1004 merge_target_bb = loop->header;
1005 for (i = 1; i < orig_loop_num_nodes; i++)
1007 gimple_stmt_iterator gsi;
1008 gimple_stmt_iterator last;
1012 if (bb == exit_bb || bb == loop->latch)
1015 /* Make stmts member of loop->header. */
1016 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1017 gimple_set_bb (gsi_stmt (gsi), merge_target_bb);
1019 /* Update stmt list. */
1020 last = gsi_last_bb (merge_target_bb);
1021 gsi_insert_seq_after (&last, bb_seq (bb), GSI_NEW_STMT);
1022 set_bb_seq (bb, NULL);
1024 delete_basic_block (bb);
1027 /* If possible, merge loop header to the block with the exit edge.
1028 This reduces the number of basic blocks to two, to please the
1029 vectorizer that handles only loops with two nodes.
1031 FIXME: Call cleanup_tree_cfg. */
1033 && exit_bb != loop->header
1034 && can_merge_blocks_p (loop->header, exit_bb))
1035 merge_blocks (loop->header, exit_bb);
1038 /* If-convert LOOP when it is legal. For the moment this pass has no
1039 profitability analysis. */
1042 tree_if_conversion (struct loop *loop)
1046 if (!if_convertible_loop_p (loop))
1049 /* Now all statements are if-convertible. Combine all the basic
1050 blocks into one huge basic block doing the if-conversion
1052 combine_blocks (loop);
1055 clean_predicate_lists (loop);
1063 /* Tree if-conversion pass management. */
1066 main_tree_if_conversion (void)
1071 if (number_of_loops () <= 1)
1074 FOR_EACH_LOOP (li, loop, 0)
1075 tree_if_conversion (loop);
1081 gate_tree_if_conversion (void)
1083 return flag_tree_vectorize != 0;
1086 struct gimple_opt_pass pass_if_conversion =
1091 gate_tree_if_conversion, /* gate */
1092 main_tree_if_conversion, /* execute */
1095 0, /* static_pass_number */
1096 TV_NONE, /* tv_id */
1097 PROP_cfg | PROP_ssa, /* properties_required */
1098 0, /* properties_provided */
1099 0, /* properties_destroyed */
1100 0, /* todo_flags_start */
1101 TODO_dump_func | TODO_verify_stmts | TODO_verify_flow
1102 /* todo_flags_finish */