/* If-conversion for vectorizer.
- Copyright (C) 2004 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
+ Free Software Foundation, Inc.
Contributed by Devang Patel <dpatel@apple.com>
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
-Software Foundation; either version 2, or (at your option) any later
+Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-02111-1307, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
-/* This pass implements tree level if-conversion transformation of loops.
- Initial goal is to help vectorizer vectorize loops with conditions.
+/* This pass implements a tree level if-conversion of loops. Its
+ initial goal is to help the vectorizer to vectorize loops with
+ conditions.
A short description of if-conversion:
- o Decide if a loop is if-convertable or not.
+ o Decide if a loop is if-convertible or not.
o Walk all loop basic blocks in breadth first order (BFS order).
o Remove conditional statements (at the end of basic block)
and propagate condition into destination basic blocks'
#include "system.h"
#include "coretypes.h"
#include "tm.h"
-#include "errors.h"
#include "tree.h"
-#include "c-common.h"
#include "flags.h"
#include "timevar.h"
#include "varray.h"
#include "tree-pass.h"
#include "target.h"
-/* local function prototypes */
-static void main_tree_if_conversion (void);
-static tree tree_if_convert_stmt (struct loop *loop, tree, tree,
- block_stmt_iterator *);
-static void tree_if_convert_cond_expr (struct loop *, tree, tree,
- block_stmt_iterator *);
-static bool if_convertable_phi_p (struct loop *, basic_block, tree);
-static bool if_convertable_modify_expr_p (struct loop *, basic_block, tree);
-static bool if_convertable_stmt_p (struct loop *, basic_block, tree);
-static bool if_convertable_bb_p (struct loop *, basic_block, bool);
-static bool if_convertable_loop_p (struct loop *, bool);
-static void add_to_predicate_list (basic_block, tree);
-static tree add_to_dst_predicate_list (struct loop * loop, tree, tree, tree,
- block_stmt_iterator *);
-static void clean_predicate_lists (struct loop *loop);
-static bool find_phi_replacement_condition (basic_block, tree *,
- block_stmt_iterator *);
-static void replace_phi_with_cond_modify_expr (tree, tree, bool,
- block_stmt_iterator *);
-static void process_phi_nodes (struct loop *);
-static void combine_blocks (struct loop *);
-static tree ifc_temp_var (tree, tree);
-static bool pred_blocks_visited_p (basic_block, bitmap *);
-static basic_block * get_loop_body_in_if_conv_order (const struct loop *loop);
-static bool bb_with_exit_edge_p (basic_block);
-
/* List of basic blocks in if-conversion-suitable order. */
static basic_block *ifc_bbs;
-/* Main entry point.
- Apply if-conversion to the LOOP. Return true if successful otherwise return
- false. If false is returned then loop remains unchanged.
- FOR_VECTORIZER is a boolean flag. It indicates whether if-conversion is used
- for vectorizer or not. If it is used for vectorizer, additional checks are
- used. (Vectorization checks are not yet implemented). */
+/* Create a new temp variable of type TYPE. Add GIMPLE_ASSIGN to assign EXP
+ to the new variable. */
-bool
-tree_if_conversion (struct loop *loop, bool for_vectorizer)
+static gimple
+ifc_temp_var (tree type, tree exp)
{
- basic_block bb;
- block_stmt_iterator itr;
- tree cond;
- unsigned int i;
+ const char *name = "_ifc_";
+ tree var, new_name;
+ gimple stmt;
- ifc_bbs = NULL;
+ /* Create new temporary variable. */
+ var = create_tmp_var (type, name);
+ add_referenced_var (var);
- /* if-conversion is not appropriate for all loops. First, check if loop is
- if-convertable or not. */
- if (!if_convertable_loop_p (loop, for_vectorizer))
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file,"-------------------------\n");
- if (ifc_bbs)
- {
- free (ifc_bbs);
- ifc_bbs = NULL;
- }
- free_dominance_info (CDI_POST_DOMINATORS);
- free_df ();
- return false;
- }
+ /* Build new statement to assign EXP to new variable. */
+ stmt = gimple_build_assign (var, exp);
- cond = NULL_TREE;
+ /* Get SSA name for the new variable and set make new statement
+ its definition statement. */
+ new_name = make_ssa_name (var, stmt);
+ gimple_assign_set_lhs (stmt, new_name);
+ SSA_NAME_DEF_STMT (new_name) = stmt;
+ update_stmt (stmt);
- /* Do actual work now. */
- for (i = 0; i < loop->num_nodes; i++)
+ return stmt;
+}
+
+/* Add condition NEW_COND to the predicate list of basic block BB. */
+
+static void
+add_to_predicate_list (basic_block bb, tree new_cond)
+{
+ tree cond = (tree) bb->aux;
+
+ if (cond)
+ cond = fold_build2_loc (EXPR_LOCATION (cond),
+ TRUTH_OR_EXPR, boolean_type_node,
+ unshare_expr (cond), new_cond);
+ else
+ cond = new_cond;
+
+ bb->aux = cond;
+}
+
+/* Add the condition COND to the previous condition PREV_COND, and add this
+ to the predicate list of the destination of edge E. GSI is the
+ place where the gimplification of the resulting condition should
+ output code. LOOP is the loop to be if-converted. */
+
+static tree
+add_to_dst_predicate_list (struct loop *loop, edge e,
+ tree prev_cond, tree cond,
+ gimple_stmt_iterator *gsi)
+{
+ tree new_cond = NULL_TREE;
+
+ if (!flow_bb_inside_loop_p (loop, e->dest))
+ return NULL_TREE;
+
+ if (prev_cond == boolean_true_node || !prev_cond)
+ new_cond = unshare_expr (cond);
+ else
{
- bb = ifc_bbs [i];
+ tree tmp;
+ gimple tmp_stmt = NULL;
- /* Update condition using predicate list. */
- cond = bb->aux;
+ prev_cond = force_gimple_operand_gsi (gsi, unshare_expr (prev_cond),
+ true, NULL, true, GSI_SAME_STMT);
- /* Process all statements in this basic block.
- Remove conditional expression, if any, and annotate
- destination basic block(s) appropriately. */
- for (itr = bsi_start (bb); !bsi_end_p (itr); /* empty */)
- {
- tree t = bsi_stmt (itr);
- cond = tree_if_convert_stmt (loop, t, cond, &itr);
- if (!bsi_end_p (itr))
- bsi_next (&itr);
- }
+ cond = force_gimple_operand_gsi (gsi, unshare_expr (cond),
+ true, NULL, true, GSI_SAME_STMT);
- /* If current bb has only one successor, then consider it as an
- unconditional goto. */
- if (bb->succ && !bb->succ->succ_next)
- {
- basic_block bb_n = bb->succ->dest;
- if (cond != NULL_TREE)
- add_to_predicate_list (bb_n, cond);
- cond = NULL_TREE;
- }
+ /* Add the condition COND to the e->aux field. In case the edge
+ destination is a PHI node, this condition will be added to
+ the block predicate to construct a complete condition. */
+ e->aux = cond;
+
+ tmp = build2 (TRUTH_AND_EXPR, boolean_type_node,
+ unshare_expr (prev_cond), cond);
+ tmp_stmt = ifc_temp_var (boolean_type_node, tmp);
+ gsi_insert_before (gsi, tmp_stmt, GSI_SAME_STMT);
+ new_cond = gimple_assign_lhs (tmp_stmt);
}
- /* Now, all statements are if-converted and basic blocks are
- annotated appropriately. Combine all basic block into one huge
- basic block. */
- combine_blocks (loop);
+ add_to_predicate_list (e->dest, new_cond);
+ return new_cond;
+}
- /* clean up */
- clean_predicate_lists (loop);
- free (ifc_bbs);
- ifc_bbs = NULL;
- free_df ();
+/* Return true if one of the successor edges of BB exits LOOP. */
- return true;
+static bool
+bb_with_exit_edge_p (struct loop *loop, basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (loop_exit_edge_p (loop, e))
+ return true;
+
+ return false;
}
-/* if-convert stmt T which is part of LOOP.
- If T is a MODIFY_EXPR than it is converted into conditional modify
- expression using COND. For conditional expressions, add condition in the
- destination basic block's predicate list and remove conditional
- expression itself. BSI is the iterator used to traverse statements of
- loop. It is used here when it is required to delete current statement. */
+/* STMT is a GIMPLE_COND. Update two destination's predicate list.
+ Remove COND_EXPR, if it is not the exit condition of LOOP.
+ Otherwise update the exit condition of LOOP appropriately. GSI
+ points to the statement STMT. */
+
+static void
+tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
+ gimple_stmt_iterator *gsi)
+{
+ tree c2;
+ edge true_edge, false_edge;
+ location_t loc = gimple_location (stmt);
+ tree c = fold_build2_loc (loc, gimple_cond_code (stmt), boolean_type_node,
+ gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
+
+ extract_true_false_edges_from_block (gimple_bb (stmt),
+ &true_edge, &false_edge);
+
+ /* Add new condition into destination's predicate list. */
+
+ /* If C is true, then TRUE_EDGE is taken. */
+ add_to_dst_predicate_list (loop, true_edge, cond, c, gsi);
+
+ /* If C is false, then FALSE_EDGE is taken. */
+ c2 = invert_truthvalue_loc (loc, unshare_expr (c));
+ add_to_dst_predicate_list (loop, false_edge, cond, c2, gsi);
+
+ /* Now this conditional statement is redundant. Remove it. But, do
+ not remove the exit condition! Update the exit condition using
+ the new condition. */
+ if (!bb_with_exit_edge_p (loop, gimple_bb (stmt)))
+ {
+ gsi_remove (gsi, true);
+ cond = NULL_TREE;
+ }
+}
+
+/* If-convert stmt T which is part of LOOP.
+
+ If T is a GIMPLE_ASSIGN then it is converted into a conditional
+ modify expression using COND. For conditional expressions, add
+ a condition in the destination basic block's predicate list and
+ remove the conditional expression itself. GSI points to the
+ statement T. */
static tree
-tree_if_convert_stmt (struct loop * loop, tree t, tree cond,
- block_stmt_iterator *bsi)
+tree_if_convert_stmt (struct loop *loop, gimple t, tree cond,
+ gimple_stmt_iterator *gsi)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "------if-convert stmt\n");
- print_generic_stmt (dump_file, t, TDF_SLIM);
+ print_gimple_stmt (dump_file, t, 0, TDF_SLIM);
print_generic_stmt (dump_file, cond, TDF_SLIM);
}
- switch (TREE_CODE (t))
+ switch (gimple_code (t))
{
/* Labels are harmless here. */
- case LABEL_EXPR:
+ case GIMPLE_LABEL:
break;
- case MODIFY_EXPR:
- /* This modify_expr is killing previous value of LHS. Appropriate value will
- be selected by PHI node based on condition. It is possible that before
- this transformation, PHI nodes was selecting default value and now it will
- use this new value. This is OK because it does not change validity the
- program. */
+ case GIMPLE_DEBUG:
+ /* ??? Should there be conditional GIMPLE_DEBUG_BINDs? */
+ if (gimple_debug_bind_p (gsi_stmt (*gsi)))
+ {
+ gimple_debug_bind_reset_value (gsi_stmt (*gsi));
+ update_stmt (gsi_stmt (*gsi));
+ }
break;
- case GOTO_EXPR:
- /* Unconditional goto */
- add_to_predicate_list (bb_for_stmt (TREE_OPERAND (t, 1)), cond);
- bsi_remove (bsi);
- cond = NULL_TREE;
+ case GIMPLE_ASSIGN:
+ /* This GIMPLE_ASSIGN is killing previous value of LHS. Appropriate
+ value will be selected by PHI node based on condition. It is possible
+ that before this transformation, PHI nodes was selecting default
+ value and now it will use this new value. This is OK because it does
+ not change the validity of the program. */
break;
- case COND_EXPR:
+ case GIMPLE_COND:
/* Update destination blocks' predicate list and remove this
condition expression. */
- tree_if_convert_cond_expr (loop, t, cond, bsi);
+ tree_if_convert_cond_stmt (loop, t, cond, gsi);
cond = NULL_TREE;
break;
default:
- abort ();
- break;
+ gcc_unreachable ();
}
- return cond;
-}
-
-/* STMT is COND_EXPR. Update two destination's predicate list.
- Remove COND_EXPR, if it is not the loop exit condition. Otherwise
- update loop exit condition appropriately. BSI is the iterator
- used to traverse statement list. STMT is part of loop LOOP. */
-
-static void
-tree_if_convert_cond_expr (struct loop *loop, tree stmt, tree cond,
- block_stmt_iterator *bsi)
-{
- tree then_clause, else_clause, c, new_cond;
- new_cond = NULL_TREE;
-#ifdef ENABLE_CHECKING
- if (TREE_CODE (stmt) != COND_EXPR)
- abort ();
-#endif
-
- c = TREE_OPERAND (stmt, 0);
- then_clause = TREE_OPERAND (stmt, 1);
- else_clause = TREE_OPERAND (stmt, 2);
-
- /* Create temp. for condition. */
- if (!is_gimple_reg (c))
- {
- tree new_stmt;
- new_stmt = ifc_temp_var (TREE_TYPE (c), unshare_expr (c));
- bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
- c = TREE_OPERAND (new_stmt, 0);
- }
-
- /* Add new condition into destination's predicate list. */
- if (then_clause)
- /* if 'c' is true then then_clause is reached. */
- new_cond = add_to_dst_predicate_list (loop, then_clause, cond, c, bsi);
-
- if (else_clause)
- {
- /* if 'c' is false then else_clause is reached. */
- tree c2 = build1 (TRUTH_NOT_EXPR,
- boolean_type_node,
- unshare_expr (c));
- add_to_dst_predicate_list (loop, else_clause, cond, c2, bsi);
- }
-
- /* Now this conditional statement is redundant. Remove it.
- But, do not remove exit condition! Update exit condition
- using new condition. */
- if (!bb_with_exit_edge_p (bb_for_stmt (stmt)))
- {
- bsi_remove (bsi);
- cond = NULL_TREE;
- }
- else if (new_cond != NULL_TREE)
- {
- TREE_OPERAND (stmt, 0) = new_cond;
- modify_stmt (stmt);
- }
- return;
+ return cond;
}
-/* Return true, iff PHI is if-convertable. PHI is part of loop LOOP
+/* Return true when PHI is if-convertible. PHI is part of loop LOOP
and it belongs to basic block BB.
- PHI is not if-convertable
- - if it has more than 2 arguments.
- - Virtual PHI is immediately used in another PHI node. */
+
+ PHI is not if-convertible if:
+ - it has more than 2 arguments,
+ - virtual PHI is immediately used in another PHI node,
+ - virtual PHI on BB other than header. */
static bool
-if_convertable_phi_p (struct loop *loop, basic_block bb, tree phi)
+if_convertible_phi_p (struct loop *loop, basic_block bb, gimple phi)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "-------------------------\n");
- print_generic_stmt (dump_file, phi, TDF_SLIM);
+ print_gimple_stmt (dump_file, phi, 0, TDF_SLIM);
}
- if (bb != loop->header && PHI_NUM_ARGS (phi) != 2)
+ if (bb != loop->header && gimple_phi_num_args (phi) != 2)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "More than two phi node args.\n");
return false;
}
- if (!is_gimple_reg (SSA_NAME_VAR (PHI_RESULT (phi))))
+ if (!is_gimple_reg (SSA_NAME_VAR (gimple_phi_result (phi))))
{
- int j;
- dataflow_t df = get_immediate_uses (phi);
- int num_uses = num_immediate_uses (df);
- for (j = 0; j < num_uses; j++)
+ imm_use_iterator imm_iter;
+ use_operand_p use_p;
+
+ if (bb != loop->header)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "Virtual phi not on loop header.\n");
+ return false;
+ }
+ FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_phi_result (phi))
{
- tree use = immediate_use (df, j);
- if (TREE_CODE (use) == PHI_NODE)
+ if (gimple_code (USE_STMT (use_p)) == GIMPLE_PHI)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Difficult to handle this virtual phi.\n");
return true;
}
-/* Return true, if M_EXPR is if-convertable.
- MODIFY_EXPR is not if-convertable if,
- - It is not movable.
- - It could trap.
+/* Return true when STMT is if-convertible.
+
+ GIMPLE_ASSIGN statement is not if-convertible if,
+ - it is not movable,
+ - it could trap,
- LHS is not var decl.
- MODIFY_EXPR is part of block BB, which is inside loop LOOP.
-*/
+
+ GIMPLE_ASSIGN is part of block BB, which is inside loop LOOP. */
static bool
-if_convertable_modify_expr_p (struct loop *loop, basic_block bb, tree m_expr)
+if_convertible_gimple_assign_stmt_p (struct loop *loop, basic_block bb,
+ gimple stmt)
{
+ tree lhs = gimple_assign_lhs (stmt);
+
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "-------------------------\n");
- print_generic_stmt (dump_file, m_expr, TDF_SLIM);
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
}
- /* Be conservative and do not handle immovable expressions. */
- if (movement_possibility (m_expr) == MOVE_IMPOSSIBLE)
+ /* Some of these constrains might be too conservative. */
+ if (stmt_ends_bb_p (stmt)
+ || gimple_has_volatile_ops (stmt)
+ || (TREE_CODE (lhs) == SSA_NAME
+ && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
+ || gimple_has_side_effects (stmt))
{
if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "stmt is movable. Don't take risk\n");
+ fprintf (dump_file, "stmt not suitable for ifcvt\n");
return false;
}
/* See if it needs speculative loading or not. */
if (bb != loop->header
- && tree_could_trap_p (TREE_OPERAND (m_expr, 1)))
+ && gimple_assign_rhs_could_trap_p (stmt))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "tree could trap...\n");
return false;
}
- if (TREE_CODE (TREE_OPERAND (m_expr, 1)) == CALL_EXPR)
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "CALL_EXPR \n");
- return false;
- }
-
- if (TREE_CODE (TREE_OPERAND (m_expr, 0)) != SSA_NAME
+ if (TREE_CODE (lhs) != SSA_NAME
&& bb != loop->header
- && !bb_with_exit_edge_p (bb))
+ && !bb_with_exit_edge_p (loop, bb))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "LHS is not var\n");
- print_generic_stmt (dump_file, m_expr, TDF_SLIM);
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
}
return false;
}
-
return true;
}
-/* Return true, iff STMT is if-convertable.
- Statement is if-convertable if,
- - It is if-convertable MODIFY_EXPR
- - IT is LABEL_EXPR, GOTO_EXPR or COND_EXPR.
- STMT is inside block BB, which is inside loop LOOP. */
+/* Return true when STMT is if-convertible.
+
+ A statement is if-convertible if:
+ - it is an if-convertible GIMPLE_ASSGIN,
+ - it is a GIMPLE_LABEL or a GIMPLE_COND.
+
+ STMT is inside BB, which is inside loop LOOP. */
static bool
-if_convertable_stmt_p (struct loop *loop, basic_block bb, tree stmt)
+if_convertible_stmt_p (struct loop *loop, basic_block bb, gimple stmt)
{
- switch (TREE_CODE (stmt))
+ switch (gimple_code (stmt))
{
- case LABEL_EXPR:
- break;
+ case GIMPLE_LABEL:
+ case GIMPLE_DEBUG:
+ case GIMPLE_COND:
+ return true;
- case MODIFY_EXPR:
-
- if (!if_convertable_modify_expr_p (loop, bb, stmt))
- return false;
- break;
-
- case GOTO_EXPR:
- case COND_EXPR:
- break;
+ case GIMPLE_ASSIGN:
+ return if_convertible_gimple_assign_stmt_p (loop, bb, stmt);
default:
/* Don't know what to do with 'em so don't do anything. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "don't know what to do\n");
- print_generic_stmt (dump_file, stmt, TDF_SLIM);
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
}
return false;
break;
return true;
}
-/* Return true, iff BB is if-convertable.
- Note: This routine does _not_ check basic block statements and phis.
- Basic block is not if-convertable if,
- - Basic block is non-empty and it is after exit block (in BFS order).
- - Basic block is after exit block but before latch.
- - Basic block edge(s) is not normal.
- EXIT_BB_SEEN is true if basic block with exit edge is already seen.
- BB is inside loop LOOP. */
+/* Return true when BB is if-convertible. This routine does not check
+ basic block's statements and phis.
+
+ A basic block is not if-convertible if:
+ - it is non-empty and it is after the exit block (in BFS order),
+ - it is after the exit block but before the latch,
+ - its edges are not normal.
+
+ EXIT_BB is the basic block containing the exit of the LOOP. BB is
+ inside LOOP. */
static bool
-if_convertable_bb_p (struct loop *loop, basic_block bb, bool exit_bb_seen)
+if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
{
edge e;
+ edge_iterator ei;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "----------[%d]-------------\n", bb->index);
- if (exit_bb_seen)
+ if (exit_bb)
{
if (bb != loop->latch)
{
fprintf (dump_file, "non empty basic block after exit bb\n");
return false;
}
+ else if (bb == loop->latch
+ && bb != exit_bb
+ && !dominated_by_p (CDI_DOMINATORS, bb, exit_bb))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "latch is not dominated by exit_block\n");
+ return false;
+ }
}
/* Be less adventurous and handle only normal edges. */
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
if (e->flags &
(EDGE_ABNORMAL_CALL | EDGE_EH | EDGE_ABNORMAL | EDGE_IRREDUCIBLE_LOOP))
{
if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file,"Difficult to handle edges\n");
+ fprintf (dump_file, "Difficult to handle edges\n");
return false;
}
return true;
}
-/* Return true, iff LOOP is if-convertable.
- LOOP is if-convertable if,
- - It is innermost.
- - It has two or more basic blocks.
- - It has only one exit.
- - Loop header is not the exit edge.
- - If its basic blocks and phi nodes are if convertable. See above for
- more info.
- FOR_VECTORIZER enables vectorizer specific checks. For example, support
- for vector conditions, data dependency checks etc.. (Not implemented yet). */
+/* Return true when all predecessor blocks of BB are visited. The
+ VISITED bitmap keeps track of the visited blocks. */
static bool
-if_convertable_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
+pred_blocks_visited_p (basic_block bb, bitmap *visited)
{
- tree phi;
+ edge e;
+ edge_iterator ei;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (!bitmap_bit_p (*visited, e->src->index))
+ return false;
+
+ return true;
+}
+
+/* Get body of a LOOP in suitable order for if-conversion. It is
+ caller's responsibility to deallocate basic block list.
+ If-conversion suitable order is, breadth first sort (BFS) order
+ with an additional constraint: select a block only if all its
+ predecessors are already selected. */
+
+static basic_block *
+get_loop_body_in_if_conv_order (const struct loop *loop)
+{
+ basic_block *blocks, *blocks_in_bfs_order;
basic_block bb;
- block_stmt_iterator itr;
+ bitmap visited;
+ unsigned int index = 0;
+ unsigned int visited_count = 0;
+
+ gcc_assert (loop->num_nodes);
+ gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+
+ blocks = XCNEWVEC (basic_block, loop->num_nodes);
+ visited = BITMAP_ALLOC (NULL);
+
+ blocks_in_bfs_order = get_loop_body_in_bfs_order (loop);
+
+ index = 0;
+ while (index < loop->num_nodes)
+ {
+ bb = blocks_in_bfs_order [index];
+
+ if (bb->flags & BB_IRREDUCIBLE_LOOP)
+ {
+ free (blocks_in_bfs_order);
+ BITMAP_FREE (visited);
+ free (blocks);
+ return NULL;
+ }
+
+ if (!bitmap_bit_p (visited, bb->index))
+ {
+ if (pred_blocks_visited_p (bb, &visited)
+ || bb == loop->header)
+ {
+ /* This block is now visited. */
+ bitmap_set_bit (visited, bb->index);
+ blocks[visited_count++] = bb;
+ }
+ }
+
+ index++;
+
+ if (index == loop->num_nodes
+ && visited_count != loop->num_nodes)
+ /* Not done yet. */
+ index = 0;
+ }
+ free (blocks_in_bfs_order);
+ BITMAP_FREE (visited);
+ return blocks;
+}
+
+/* Return true when LOOP is if-convertible.
+ LOOP is if-convertible if:
+ - it is innermost,
+ - it has two or more basic blocks,
+ - it has only one exit,
+ - loop header is not the exit edge,
+ - if its basic blocks and phi nodes are if convertible. */
+
+static bool
+if_convertible_loop_p (struct loop *loop)
+{
+ basic_block bb;
+ gimple_stmt_iterator itr;
unsigned int i;
edge e;
- bool exit_bb_seen = false;
+ edge_iterator ei;
+ basic_block exit_bb = NULL;
/* Handle only inner most loop. */
if (!loop || loop->inner)
return false;
}
- flow_loop_scan (loop, LOOP_ALL);
-
/* If only one block, no need for if-conversion. */
if (loop->num_nodes <= 2)
{
}
/* More than one loop exit is too much to handle. */
- if (loop->num_exits > 1)
+ if (!single_exit (loop))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "multiple exits\n");
/* If one of the loop header's edge is exit edge then do not apply
if-conversion. */
- for (e = loop->header->succ; e; e = e->succ_next)
- if ( e->flags & EDGE_LOOP_EXIT)
- return false;
-
- compute_immediate_uses (TDFA_USE_OPS|TDFA_USE_VOPS, NULL);
+ FOR_EACH_EDGE (e, ei, loop->header->succs)
+ {
+ if (loop_exit_edge_p (loop, e))
+ return false;
+ }
calculate_dominance_info (CDI_DOMINATORS);
calculate_dominance_info (CDI_POST_DOMINATORS);
{
bb = ifc_bbs[i];
- if (!if_convertable_bb_p (loop, bb, exit_bb_seen))
+ if (!if_convertible_bb_p (loop, bb, exit_bb))
return false;
- /* Check statements. */
- for (itr = bsi_start (bb); !bsi_end_p (itr); bsi_next (&itr))
- if (!if_convertable_stmt_p (loop, bb, bsi_stmt (itr)))
+ for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
+ if (!if_convertible_stmt_p (loop, bb, gsi_stmt (itr)))
return false;
- /* ??? Check data dependency for vectorizer. */
- /* What about phi nodes ? */
- for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
- if (!if_convertable_phi_p (loop, bb, phi))
+ itr = gsi_start_phis (bb);
+
+ if (!gsi_end_p (itr))
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ e->aux = NULL;
+
+ for (; !gsi_end_p (itr); gsi_next (&itr))
+ if (!if_convertible_phi_p (loop, bb, gsi_stmt (itr)))
return false;
- if (bb_with_exit_edge_p (bb))
- exit_bb_seen = true;
+ if (bb_with_exit_edge_p (loop, bb))
+ exit_bb = bb;
}
- /* OK. Did not find any potential issues so go ahead in if-convert
- this loop. Now there is no looking back. */
if (dump_file)
fprintf (dump_file,"Applying if-conversion\n");
return true;
}
-/* Add condition COND into predicate list of basic block BB. */
+/* During if-conversion, the bb->aux field is used to hold a predicate
+ list. This function cleans for all the basic blocks in the given
+ LOOP their predicate list. It also cleans up the e->aux field of
+ all the successor edges: e->aux is used to hold the true and false
+ conditions for conditional expressions. */
static void
-add_to_predicate_list (basic_block bb, tree new_cond)
+clean_predicate_lists (struct loop *loop)
{
- tree cond = bb->aux;
-
- if (cond)
- cond = fold (build (TRUTH_OR_EXPR, boolean_type_node,
- unshare_expr (cond), new_cond));
- else
- cond = new_cond;
+ basic_block *bb;
+ unsigned int i;
+ edge e;
+ edge_iterator ei;
- bb->aux = cond;
+ bb = get_loop_body (loop);
+ for (i = 0; i < loop->num_nodes; i++)
+ {
+ bb[i]->aux = NULL;
+ FOR_EACH_EDGE (e, ei, bb[i]->succs)
+ e->aux = NULL;
+ }
+ free (bb);
}
-/* Add condition COND into DST's predicate list. PREV_COND is
- existing condition. */
+/* Basic block BB has two predecessors. Using predecessor's bb->aux
+ field, set appropriate condition COND for the PHI node replacement.
+ Return true block whose phi arguments are selected when cond is
+ true. LOOP is the loop containing the if-converted region, GSI is
+ the place to insert the code for the if-conversion. */
-static tree
-add_to_dst_predicate_list (struct loop * loop, tree dst,
- tree prev_cond, tree cond,
- block_stmt_iterator *bsi)
+static basic_block
+find_phi_replacement_condition (struct loop *loop,
+ basic_block bb, tree *cond,
+ gimple_stmt_iterator *gsi)
{
- basic_block bb;
- tree new_cond = NULL_TREE;
+ edge first_edge, second_edge;
+ tree tmp_cond;
-#ifdef ENABLE_CHECKING
- if (TREE_CODE (dst) != GOTO_EXPR)
- abort ();
-#endif
- bb = label_to_block (TREE_OPERAND (dst, 0));
- if (!flow_bb_inside_loop_p (loop, bb))
- return NULL_TREE;
+ gcc_assert (EDGE_COUNT (bb->preds) == 2);
+ first_edge = EDGE_PRED (bb, 0);
+ second_edge = EDGE_PRED (bb, 1);
- if (prev_cond == boolean_true_node || !prev_cond)
- new_cond = unshare_expr (cond);
- else
- {
- tree tmp_stmt;
- /* new_cond == prev_cond AND cond */
- tree tmp = build (TRUTH_AND_EXPR, boolean_type_node,
- unshare_expr (prev_cond), cond);
- tmp_stmt = ifc_temp_var (boolean_type_node, tmp);
- bsi_insert_before (bsi, tmp_stmt, BSI_SAME_STMT);
- new_cond = TREE_OPERAND (tmp_stmt, 0);
- }
- add_to_predicate_list (bb, new_cond);
- return new_cond;
-}
+ /* Use condition based on following criteria:
+ 1)
+ S1: x = !c ? a : b;
-/* During if-conversion aux field from basic block is used to hold predicate
- list. Clean each basic block's predicate list for the given LOOP. */
+ S2: x = c ? b : a;
-static void
-clean_predicate_lists (struct loop *loop)
-{
- unsigned int i;
+ S2 is preferred over S1. Make 'b' first_bb and use its condition.
- for (i = 0; i < loop->num_nodes; i++)
- ifc_bbs[i]->aux = NULL;
-}
+ 2) Do not make loop header first_bb.
-/* Basic block BB has two predecessors. Using predecessor's aux field, set
- appropriate condition COND for the PHI node replacement. Return true if
- phi arguments are condition is selected from second predecessor. */
+ 3)
+ S1: x = !(c == d)? a : b;
-static bool
-find_phi_replacement_condition (basic_block bb, tree *cond,
- block_stmt_iterator *bsi)
-{
- edge e;
- basic_block p1 = NULL;
- basic_block p2 = NULL;
- bool switch_args = false;
- tree tmp_cond;
+ S21: t1 = c == d;
+ S22: x = t1 ? b : a;
+
+ S3: x = (c == d) ? b : a;
+
+ S3 is preferred over S1 and S2*, Make 'b' first_bb and use
+ its condition.
- for (e = bb->pred; e; e = e->pred_next)
+ 4) If pred B is dominated by pred A then use pred B's condition.
+ See PR23115. */
+
+ /* Select condition that is not TRUTH_NOT_EXPR. */
+ tmp_cond = (tree) (first_edge->src)->aux;
+ gcc_assert (tmp_cond);
+
+ if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
{
- if (p1 == NULL)
- p1 = e->src;
- else if (p2 == NULL)
- p2 = e->src;
- else
- /* More than two predecessors. This is not expected. */
- abort ();
+ edge tmp_edge;
+
+ tmp_edge = first_edge;
+ first_edge = second_edge;
+ second_edge = tmp_edge;
}
- /* Use condition that is not TRUTH_NOT_EXPR in conditional modify expr. */
- tmp_cond = p1->aux;
- if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
+ /* Check if FIRST_BB is loop header or not and make sure that
+ FIRST_BB does not dominate SECOND_BB. */
+ if (first_edge->src == loop->header
+ || dominated_by_p (CDI_DOMINATORS,
+ second_edge->src, first_edge->src))
{
- *cond = p2->aux;
- switch_args = true;
+ *cond = (tree) (second_edge->src)->aux;
+
+ /* If there is a condition on an incoming edge, add it to the
+ incoming bb predicate. */
+ if (second_edge->aux)
+ *cond = build2 (TRUTH_AND_EXPR, boolean_type_node,
+ *cond, (tree) second_edge->aux);
+
+ if (TREE_CODE (*cond) == TRUTH_NOT_EXPR)
+ *cond = invert_truthvalue (*cond);
+ else
+ /* Select non loop header bb. */
+ first_edge = second_edge;
}
else
{
- *cond = p1->aux;
- switch_args = false;
+ *cond = (tree) (first_edge->src)->aux;
+
+ /* If there is a condition on an incoming edge, add it to the
+ incoming bb predicate. */
+ if (first_edge->aux)
+ *cond = build2 (TRUTH_AND_EXPR, boolean_type_node,
+ *cond, (tree) first_edge->aux);
}
- /* Create temp. for the condition. Vectorizer prefers to have gimple
- value as condition. Various targets use different means to communicate
- condition in vector compare operation. Using gimple value allows compiler
- to emit vector compare and select RTL without exposing compare's result. */
+ /* Gimplify the condition: the vectorizer prefers to have gimple
+ values as conditions. Various targets use different means to
+ communicate conditions in vector compare operations. Using a
+ gimple value allows the compiler to emit vector compare and
+ select RTL without exposing compare's result. */
+ *cond = force_gimple_operand_gsi (gsi, unshare_expr (*cond),
+ false, NULL_TREE,
+ true, GSI_SAME_STMT);
if (!is_gimple_reg (*cond) && !is_gimple_condexpr (*cond))
{
- tree new_stmt;
+ gimple new_stmt;
new_stmt = ifc_temp_var (TREE_TYPE (*cond), unshare_expr (*cond));
- bsi_insert_after (bsi, new_stmt, BSI_SAME_STMT);
- bsi_next (bsi);
- *cond = TREE_OPERAND (new_stmt, 0);
+ gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
+ *cond = gimple_assign_lhs (new_stmt);
}
-#ifdef ENABLE_CHECKING
- if (*cond == NULL_TREE)
- abort ();
-#endif
+ gcc_assert (*cond);
- return switch_args;
+ return first_edge->src;
}
+/* Replace PHI node with conditional modify expr using COND. This
+ routine does not handle PHI nodes with more than two arguments.
-/* Replace PHI node with conditional modify expr using COND.
- This routine does not handle PHI nodes with more than two arguments.
For example,
S1: A = PHI <x1(1), x2(5)
is converted into,
S2: A = cond ? x1 : x2;
- S2 is inserted at the top of basic block's statement list.
- PHI arguments are switched if SWITCH_ARGS is true.
-*/
+
+ The generated code is inserted at GSI that points to the top of
+ basic block's statement list. When COND is true, phi arg from
+ TRUE_BB is selected. */
static void
-replace_phi_with_cond_modify_expr (tree phi, tree cond, bool switch_args,
- block_stmt_iterator *bsi)
+replace_phi_with_cond_gimple_assign_stmt (gimple phi, tree cond,
+ basic_block true_bb,
+ gimple_stmt_iterator *gsi)
{
- tree new_stmt;
+ gimple new_stmt;
basic_block bb;
tree rhs;
tree arg_0, arg_1;
-#ifdef ENABLE_CHECKING
- if (TREE_CODE (phi) != PHI_NODE)
- abort ();
+ gcc_assert (gimple_code (phi) == GIMPLE_PHI
+ && gimple_phi_num_args (phi) == 2);
- /* If this is not filtered earlier, then now it is too late. */
- if (PHI_NUM_ARGS (phi) != 2)
- abort ();
-#endif
-
- /* Find basic block and initialize iterator. */
- bb = bb_for_stmt (phi);
-
- new_stmt = NULL_TREE;
- arg_0 = NULL_TREE;
- arg_1 = NULL_TREE;
+ bb = gimple_bb (phi);
/* Use condition that is not TRUTH_NOT_EXPR in conditional modify expr. */
- if (switch_args)
+ if (EDGE_PRED (bb, 1)->src == true_bb)
{
- arg_0 = PHI_ARG_DEF (phi, 1);
- arg_1 = PHI_ARG_DEF (phi, 0);
+ arg_0 = gimple_phi_arg_def (phi, 1);
+ arg_1 = gimple_phi_arg_def (phi, 0);
}
else
{
- arg_0 = PHI_ARG_DEF (phi, 0);
- arg_1 = PHI_ARG_DEF (phi, 1);
+ arg_0 = gimple_phi_arg_def (phi, 0);
+ arg_1 = gimple_phi_arg_def (phi, 1);
}
/* Build new RHS using selected condition and arguments. */
- rhs = build (COND_EXPR, TREE_TYPE (PHI_RESULT (phi)),
- unshare_expr (cond), unshare_expr (arg_0),
- unshare_expr (arg_1));
-
- /* Create new MODIFY expression using RHS. */
- new_stmt = build (MODIFY_EXPR, TREE_TYPE (PHI_RESULT (phi)),
- unshare_expr (PHI_RESULT (phi)), rhs);
+ rhs = build3 (COND_EXPR, TREE_TYPE (PHI_RESULT (phi)),
+ unshare_expr (cond), unshare_expr (arg_0),
+ unshare_expr (arg_1));
- /* Make new statement definition of the original phi result. */
- SSA_NAME_DEF_STMT (PHI_RESULT (phi)) = new_stmt;
-
- /* Set basic block and insert using iterator. */
- set_bb_for_stmt (new_stmt, bb);
-
- bsi_insert_after (bsi, new_stmt, BSI_SAME_STMT);
- bsi_next (bsi);
-
- modify_stmt (new_stmt);
+ new_stmt = gimple_build_assign (unshare_expr (PHI_RESULT (phi)), rhs);
+ SSA_NAME_DEF_STMT (gimple_phi_result (phi)) = new_stmt;
+ gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
+ update_stmt (new_stmt);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "new phi replacement stmt\n");
- print_generic_stmt (dump_file, new_stmt, TDF_SLIM);
+ print_gimple_stmt (dump_file, new_stmt, 0, TDF_SLIM);
}
}
-/* Process phi nodes for the given LOOP. Replace phi nodes with cond
- modify expr. */
+/* Process phi nodes for the given LOOP. Replace phi nodes with
+ conditional modify expressions. */
static void
process_phi_nodes (struct loop *loop)
unsigned int orig_loop_num_nodes = loop->num_nodes;
unsigned int i;
- /* Replace phi nodes with cond. modify expr. */
for (i = 1; i < orig_loop_num_nodes; i++)
{
- tree phi, cond;
- block_stmt_iterator bsi;
- bool switch_args = false;
+ gimple phi;
+ tree cond = NULL_TREE;
+ gimple_stmt_iterator gsi, phi_gsi;
+ basic_block true_bb = NULL;
bb = ifc_bbs[i];
- if (bb == loop->header || bb == loop->latch)
+ if (bb == loop->header)
continue;
- phi = phi_nodes (bb);
- bsi = bsi_start (bb);
+ phi_gsi = gsi_start_phis (bb);
+ gsi = gsi_after_labels (bb);
- /* BB has two predecessors. Using predecessor's aux field, set
+ /* BB has two predecessors. Using predecessor's aux field, set
appropriate condition for the PHI node replacement. */
- if (phi)
- switch_args = find_phi_replacement_condition (bb, &cond, &bsi);
+ if (!gsi_end_p (phi_gsi))
+ true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
- while (phi)
+ while (!gsi_end_p (phi_gsi))
{
- tree next = TREE_CHAIN (phi);
- replace_phi_with_cond_modify_expr (phi, cond, switch_args, &bsi);
+ phi = gsi_stmt (phi_gsi);
+ replace_phi_with_cond_gimple_assign_stmt (phi, cond, true_bb, &gsi);
release_phi_node (phi);
- phi = next;
+ gsi_next (&phi_gsi);
}
- bb_ann (bb)->phi_nodes = NULL;
+ set_phi_nodes (bb, NULL);
}
- return;
}
-/* Combine all basic block from the given LOOP into one or two super
- basic block. Replace PHI nodes with conditional modify expression. */
+/* Combine all the basic blocks from LOOP into one or two super basic
+ blocks. Replace PHI nodes with conditional modify expressions. */
static void
combine_blocks (struct loop *loop)
basic_block bb, exit_bb, merge_target_bb;
unsigned int orig_loop_num_nodes = loop->num_nodes;
unsigned int i;
+ edge e;
+ edge_iterator ei;
/* Process phi nodes to prepare blocks for merge. */
process_phi_nodes (loop);
+ /* Merge basic blocks: first remove all the edges in the loop,
+ except for those from the exit block. */
exit_bb = NULL;
+ for (i = 0; i < orig_loop_num_nodes; i++)
+ {
+ bb = ifc_bbs[i];
+ if (bb_with_exit_edge_p (loop, bb))
+ {
+ exit_bb = bb;
+ break;
+ }
+ }
+ gcc_assert (exit_bb != loop->latch);
- /* Merge basic blocks */
- merge_target_bb = loop->header;
for (i = 1; i < orig_loop_num_nodes; i++)
{
- edge e;
- block_stmt_iterator bsi;
- tree_stmt_iterator last;
-
bb = ifc_bbs[i];
- if (bb == loop->latch)
- continue;
+ for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei));)
+ {
+ if (e->src == exit_bb)
+ ei_next (&ei);
+ else
+ remove_edge (e);
+ }
+ }
- if (!exit_bb && bb_with_exit_edge_p (bb))
- exit_bb = bb;
+ if (exit_bb != NULL)
+ {
+ if (exit_bb != loop->header)
+ {
+ /* Connect this node to loop header. */
+ make_edge (loop->header, exit_bb, EDGE_FALLTHRU);
+ set_immediate_dominator (CDI_DOMINATORS, exit_bb, loop->header);
+ }
- if (bb == exit_bb)
+ /* Redirect non-exit edges to loop->latch. */
+ FOR_EACH_EDGE (e, ei, exit_bb->succs)
{
- edge new_e;
+ if (!loop_exit_edge_p (loop, e))
+ redirect_edge_and_branch (e, loop->latch);
+ }
+ set_immediate_dominator (CDI_DOMINATORS, loop->latch, exit_bb);
+ }
+ else
+ {
+ /* If the loop does not have an exit, reconnect header and latch. */
+ make_edge (loop->header, loop->latch, EDGE_FALLTHRU);
+ set_immediate_dominator (CDI_DOMINATORS, loop->latch, loop->header);
+ }
- /* Connect this node with loop header. */
- new_e = make_edge (ifc_bbs[0], bb, EDGE_FALLTHRU);
- set_immediate_dominator (CDI_DOMINATORS, bb, ifc_bbs[0]);
+ merge_target_bb = loop->header;
+ for (i = 1; i < orig_loop_num_nodes; i++)
+ {
+ gimple_stmt_iterator gsi;
+ gimple_stmt_iterator last;
- if (exit_bb != loop->latch)
- {
- /* Redirect non-exit edge to loop->latch. */
- for (e = bb->succ; e; e = e->succ_next)
- if (!(e->flags & EDGE_LOOP_EXIT))
- {
- redirect_edge_and_branch (e, loop->latch);
- set_immediate_dominator (CDI_DOMINATORS, loop->latch, bb);
- }
- }
- continue;
- }
+ bb = ifc_bbs[i];
- /* It is time to remove this basic block. First remove edges. */
- while (bb->succ != NULL)
- ssa_remove_edge (bb->succ);
- while (bb->pred != NULL)
- ssa_remove_edge (bb->pred);
+ if (bb == exit_bb || bb == loop->latch)
+ continue;
/* Remove labels and make stmts member of loop->header. */
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
{
- if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
- bsi_remove (&bsi);
+ if (gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL)
+ gsi_remove (&gsi, true);
else
{
- set_bb_for_stmt (bsi_stmt (bsi), merge_target_bb);
- bsi_next (&bsi);
+ gimple_set_bb (gsi_stmt (gsi), merge_target_bb);
+ gsi_next (&gsi);
}
}
/* Update stmt list. */
- last = tsi_last (merge_target_bb->stmt_list);
- tsi_link_after (&last, bb->stmt_list, TSI_NEW_STMT);
- bb->stmt_list = NULL;
-
- /* Update dominator info. */
- if (dom_computed[CDI_DOMINATORS])
- delete_from_dominance_info (CDI_DOMINATORS, bb);
- if (dom_computed[CDI_POST_DOMINATORS])
- delete_from_dominance_info (CDI_POST_DOMINATORS, bb);
-
- /* Remove basic block. */
- remove_bb_from_loops (bb);
- expunge_block (bb);
- }
-}
+ last = gsi_last_bb (merge_target_bb);
+ gsi_insert_seq_after (&last, bb_seq (bb), GSI_NEW_STMT);
+ set_bb_seq (bb, NULL);
-/* Make new temp variable of type TYPE. Add MODIFY_EXPR to assign EXP
- to the new variable. */
-
-static tree
-ifc_temp_var (tree type, tree exp)
-{
- const char *name = "_ifc_";
- tree var, stmt, new_name;
-
- if (is_gimple_reg (exp))
- return exp;
-
- /* Create new temporary variable. */
- var = create_tmp_var (type, name);
- add_referenced_tmp_var (var);
+ delete_basic_block (bb);
+ }
- /* Build new statement to assigne EXP to new variable. */
- stmt = build (MODIFY_EXPR, type, var, exp);
+ /* If possible, merge loop header to the block with the exit edge.
+ This reduces the number of basic blocks to two, to please the
+ vectorizer that handles only loops with two nodes.
- /* Get SSA name for the new variable and set make new statement
- its definition statment. */
- new_name = make_ssa_name (var, stmt);
- TREE_OPERAND (stmt, 0) = new_name;
- SSA_NAME_DEF_STMT (new_name) = stmt;
-
- return stmt;
+ FIXME: Call cleanup_tree_cfg. */
+ if (exit_bb
+ && exit_bb != loop->header
+ && can_merge_blocks_p (loop->header, exit_bb))
+ merge_blocks (loop->header, exit_bb);
}
-
-/* Return TRUE iff, all pred blocks of BB are visited.
- Bitmap VISITED keeps history of visited blocks. */
+/* Main entry point: return true when LOOP is if-converted, otherwise
+ the loop remains unchanged. */
static bool
-pred_blocks_visited_p (basic_block bb, bitmap *visited)
-{
- edge e;
- for (e = bb->pred; e; e = e->pred_next)
- if (!bitmap_bit_p (*visited, e->src->index))
- return false;
-
- return true;
-}
-
-/* Get body of a LOOP in suitable order for if-conversion.
- It is caller's responsibility to deallocate basic block
- list. If-conversion suitable order is, BFS order with one
- additional constraint. Select block in BFS block, if all
- pred are already selected. */
-
-static basic_block *
-get_loop_body_in_if_conv_order (const struct loop *loop)
+tree_if_conversion (struct loop *loop)
{
- basic_block *blocks, *blocks_in_bfs_order;
- basic_block bb;
- bitmap visited;
- unsigned int index = 0;
- unsigned int visited_count = 0;
-
- if (!loop->num_nodes)
- abort ();
-
- if (loop->latch == EXIT_BLOCK_PTR)
- abort ();
-
- blocks = xcalloc (loop->num_nodes, sizeof (basic_block));
- visited = BITMAP_XMALLOC ();
+ gimple_stmt_iterator itr;
+ unsigned int i;
- blocks_in_bfs_order = get_loop_body_in_bfs_order (loop);
+ ifc_bbs = NULL;
- index = 0;
- while (index < loop->num_nodes)
+ /* If-conversion is not appropriate for all loops. First, check if
+ the loop is if-convertible. */
+ if (!if_convertible_loop_p (loop))
{
- bb = blocks_in_bfs_order [index];
-
- if (bb->flags & BB_IRREDUCIBLE_LOOP)
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file,"-------------------------\n");
+ if (ifc_bbs)
{
- free (blocks_in_bfs_order);
- BITMAP_FREE (visited);
- free (blocks);
- return NULL;
+ free (ifc_bbs);
+ ifc_bbs = NULL;
}
- if (!bitmap_bit_p (visited, bb->index))
+ free_dominance_info (CDI_POST_DOMINATORS);
+ return false;
+ }
+
+ for (i = 0; i < loop->num_nodes; i++)
+ {
+ basic_block bb = ifc_bbs [i];
+ tree cond = (tree) bb->aux;
+
+ /* Process all the statements in this basic block.
+ Remove conditional expression, if any, and annotate
+ destination basic block(s) appropriately. */
+ for (itr = gsi_start_bb (bb); !gsi_end_p (itr); /* empty */)
{
- if (pred_blocks_visited_p (bb, &visited)
- || bb == loop->header)
- {
- /* This block is now visited. */
- bitmap_set_bit (visited, bb->index);
- blocks[visited_count++] = bb;
- }
+ gimple t = gsi_stmt (itr);
+ cond = tree_if_convert_stmt (loop, t, cond, &itr);
+ if (!gsi_end_p (itr))
+ gsi_next (&itr);
}
- index++;
- if (index == loop->num_nodes
- && visited_count != loop->num_nodes)
+
+ /* If current bb has only one successor, then consider it as an
+ unconditional goto. */
+ if (single_succ_p (bb))
{
- /* Not done yet. */
- index = 0;
+ basic_block bb_n = single_succ (bb);
+
+ /* The successor bb inherits the predicate of its
+ predecessor. If there is no predicate in the predecessor
+ bb, then consider the successor bb as always executed. */
+ if (cond == NULL_TREE)
+ cond = boolean_true_node;
+
+ add_to_predicate_list (bb_n, cond);
}
}
- free (blocks_in_bfs_order);
- BITMAP_XFREE (visited);
- return blocks;
-}
-
-/* Return true if one of the basic block BB edge is loop exit. */
-static bool
-bb_with_exit_edge_p (basic_block bb)
-{
- edge e;
- bool exit_edge_found = false;
+ /* Now, all statements are if-converted and basic blocks are
+ annotated appropriately. Combine all the basic blocks into one
+ huge basic block. */
+ combine_blocks (loop);
- for (e = bb->succ; e && !exit_edge_found ; e = e->succ_next)
- if (e->flags & EDGE_LOOP_EXIT)
- exit_edge_found = true;
+ /* clean up */
+ clean_predicate_lists (loop);
+ free (ifc_bbs);
+ ifc_bbs = NULL;
- return exit_edge_found;
+ return true;
}
/* Tree if-conversion pass management. */
-static void
+static unsigned int
main_tree_if_conversion (void)
{
- unsigned i, loop_num;
+ loop_iterator li;
struct loop *loop;
- if (!current_loops)
- return;
-
- loop_num = current_loops->num;
- for (i = 0; i < loop_num; i++)
- {
- loop = current_loops->parray[i];
- if (!loop)
- continue;
+ if (number_of_loops () <= 1)
+ return 0;
- tree_if_conversion (loop, true);
- }
+ FOR_EACH_LOOP (li, loop, 0)
+ tree_if_conversion (loop);
+ return 0;
}
static bool
gate_tree_if_conversion (void)
{
- return true;
+ return flag_tree_vectorize != 0;
}
-struct tree_opt_pass pass_if_conversion =
+struct gimple_opt_pass pass_if_conversion =
{
- "ifcvt", /* name */
- gate_tree_if_conversion, /* gate */
- main_tree_if_conversion, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- TODO_dump_func, /* todo_flags_start */
- TODO_dump_func
- | TODO_verify_ssa
- | TODO_verify_stmts
- | TODO_verify_flow /* todo_flags_finish */
+ {
+ GIMPLE_PASS,
+ "ifcvt", /* name */
+ gate_tree_if_conversion, /* gate */
+ main_tree_if_conversion, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_NONE, /* tv_id */
+ PROP_cfg | PROP_ssa, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func | TODO_verify_stmts | TODO_verify_flow
+ /* todo_flags_finish */
+ }
};
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