/* Optimization of PHI nodes by converting them into straightline code.
- Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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
+Free 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
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/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
-#include "errors.h"
#include "ggc.h"
#include "tree.h"
#include "rtl.h"
#include "tree-pass.h"
#include "tree-dump.h"
#include "langhooks.h"
+#include "pointer-set.h"
+#include "domwalk.h"
-static void tree_ssa_phiopt (void);
-static bool conditional_replacement (basic_block, basic_block, basic_block,
+static unsigned int tree_ssa_phiopt_worker (bool);
+static bool conditional_replacement (basic_block, basic_block,
edge, edge, tree, tree, tree);
-static bool value_replacement (basic_block, basic_block, basic_block,
+static bool value_replacement (basic_block, basic_block,
edge, edge, tree, tree, tree);
-static bool minmax_replacement (basic_block, basic_block, basic_block,
+static bool minmax_replacement (basic_block, basic_block,
edge, edge, tree, tree, tree);
-static bool abs_replacement (basic_block, basic_block, basic_block,
+static bool abs_replacement (basic_block, basic_block,
edge, edge, tree, tree, tree);
-static void replace_phi_edge_with_variable (basic_block, basic_block, edge,
- tree, tree);
-static basic_block *blocks_in_phiopt_order (void);
+static bool cond_store_replacement (basic_block, basic_block, edge, edge,
+ struct pointer_set_t *);
+static struct pointer_set_t * get_non_trapping (void);
+static void replace_phi_edge_with_variable (basic_block, edge, tree, tree);
-/* This pass eliminates PHI nodes which can be trivially implemented as
- an assignment from a conditional expression. i.e. if we have something
- like:
+/* This pass tries to replaces an if-then-else block with an
+ assignment. We have four kinds of transformations. Some of these
+ transformations are also performed by the ifcvt RTL optimizer.
+
+ Conditional Replacement
+ -----------------------
+
+ This transformation, implemented in conditional_replacement,
+ replaces
bb0:
if (cond) goto bb2; else goto bb1;
bb1:
bb2:
- x = PHI (0 (bb1), 1 (bb0)
+ x = PHI <0 (bb1), 1 (bb0), ...>;
- We can rewrite that as:
+ with
bb0:
- bb1:
+ x' = cond;
+ goto bb2;
bb2:
- x = cond;
+ x = PHI <x' (bb0), ...>;
+
+ We remove bb1 as it becomes unreachable. This occurs often due to
+ gimplification of conditionals.
- bb1 will become unreachable and bb0 and bb2 will almost always
- be merged into a single block. This occurs often due to gimplification
- of conditionals.
+ Value Replacement
+ -----------------
- Also done is the following optimization:
+ This transformation, implemented in value_replacement, replaces
bb0:
- if (a != b) goto bb2; else goto bb1;
+ if (a != b) goto bb2; else goto bb1;
bb1:
bb2:
- x = PHI (a (bb1), b (bb0))
+ x = PHI <a (bb1), b (bb0), ...>;
- We can rewrite that as:
+ with
bb0:
- bb1:
bb2:
- x = b;
+ x = PHI <b (bb0), ...>;
+
+ This opportunity can sometimes occur as a result of other
+ optimizations.
- This can sometimes occur as a result of other optimizations. A
- similar transformation is done by the ifcvt RTL optimizer.
+ ABS Replacement
+ ---------------
- This pass also eliminates PHI nodes which are really absolute
- values. i.e. if we have something like:
+ This transformation, implemented in abs_replacement, replaces
bb0:
- if (a >= 0) goto bb2; else goto bb1;
+ if (a >= 0) goto bb2; else goto bb1;
bb1:
- x = -a;
+ x = -a;
+ bb2:
+ x = PHI <x (bb1), a (bb0), ...>;
+
+ with
+
+ bb0:
+ x' = ABS_EXPR< a >;
bb2:
- x = PHI (x (bb1), a (bb0));
+ x = PHI <x' (bb0), ...>;
+
+ MIN/MAX Replacement
+ -------------------
- We can rewrite that as:
+ This transformation, minmax_replacement replaces
bb0:
+ if (a <= b) goto bb2; else goto bb1;
bb1:
bb2:
- x = ABS_EXPR< a >;
+ x = PHI <b (bb1), a (bb0), ...>;
- Similarly,
+ with
bb0:
- if (a <= b) goto bb2; else goto bb1;
+ x' = MIN_EXPR (a, b)
+ bb2:
+ x = PHI <x' (bb0), ...>;
+
+ A similar transformation is done for MAX_EXPR. */
+
+static unsigned int
+tree_ssa_phiopt (void)
+{
+ return tree_ssa_phiopt_worker (false);
+}
+
+/* This pass tries to transform conditional stores into unconditional
+ ones, enabling further simplifications with the simpler then and else
+ blocks. In particular it replaces this:
+
+ bb0:
+ if (cond) goto bb2; else goto bb1;
bb1:
- goto bb2;
+ *p = RHS
bb2:
- x = PHI (b (bb1), a (bb0));
- Becomes
+ with
+
+ bb0:
+ if (cond) goto bb1; else goto bb2;
+ bb1:
+ condtmp' = *p;
+ bb2:
+ condtmp = PHI <RHS, condtmp'>
+ *p = condtmp
- x = MIN_EXPR (a, b)
+ This transformation can only be done under several constraints,
+ documented below. */
- And the same transformation for MAX_EXPR.
+static unsigned int
+tree_ssa_cs_elim (void)
+{
+ return tree_ssa_phiopt_worker (true);
+}
- bb1 will become unreachable and bb0 and bb2 will almost always be merged
- into a single block. Similar transformations are done by the ifcvt
- RTL optimizer. */
+/* For conditional store replacement we need a temporary to
+ put the old contents of the memory in. */
+static tree condstoretemp;
-static void
-tree_ssa_phiopt (void)
+/* The core routine of conditional store replacement and normal
+ phi optimizations. Both share much of the infrastructure in how
+ to match applicable basic block patterns. DO_STORE_ELIM is true
+ when we want to do conditional store replacement, false otherwise. */
+static unsigned int
+tree_ssa_phiopt_worker (bool do_store_elim)
{
basic_block bb;
basic_block *bb_order;
unsigned n, i;
+ bool cfgchanged = false;
+ struct pointer_set_t *nontrap = 0;
+
+ if (do_store_elim)
+ {
+ condstoretemp = NULL_TREE;
+ /* Calculate the set of non-trapping memory accesses. */
+ nontrap = get_non_trapping ();
+ }
/* Search every basic block for COND_EXPR we may be able to optimize.
outer ones, and also that we do not try to visit a removed
block. */
bb_order = blocks_in_phiopt_order ();
- n = n_basic_blocks;
+ n = n_basic_blocks - NUM_FIXED_BLOCKS;
- for (i = 0; i < n; i++)
+ for (i = 0; i < n; i++)
{
tree cond_expr;
tree phi;
e1 = EDGE_SUCC (bb1, 0);
/* Make sure that bb1 is just a fall through. */
- if (!single_succ_p (bb1) > 1
+ if (!single_succ_p (bb1)
|| (e1->flags & EDGE_FALLTHRU) == 0)
continue;
- /* Also make that bb1 only have one pred and it is bb. */
+ /* Also make sure that bb1 only have one predecessor and that it
+ is bb. */
if (!single_pred_p (bb1)
|| single_pred (bb1) != bb)
continue;
- phi = phi_nodes (bb2);
-
- /* Check to make sure that there is only one PHI node.
- TODO: we could do it with more than one iff the other PHI nodes
- have the same elements for these two edges. */
- if (!phi || PHI_CHAIN (phi) != NULL)
- continue;
-
- arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx);
- arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx);
-
- /* We know something is wrong if we cannot find the edges in the PHI
- node. */
- gcc_assert (arg0 != NULL && arg1 != NULL);
-
- /* Do the replacement of conditional if it can be done. */
- if (conditional_replacement (bb, bb1, bb2, e1, e2, phi, arg0, arg1))
- ;
- else if (value_replacement (bb, bb1, bb2, e1, e2, phi, arg0, arg1))
- ;
- else if (abs_replacement (bb, bb1, bb2, e1, e2, phi, arg0, arg1))
- ;
+ if (do_store_elim)
+ {
+ /* bb1 is the middle block, bb2 the join block, bb the split block,
+ e1 the fallthrough edge from bb1 to bb2. We can't do the
+ optimization if the join block has more than two predecessors. */
+ if (EDGE_COUNT (bb2->preds) > 2)
+ continue;
+ if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
+ cfgchanged = true;
+ }
else
- minmax_replacement (bb, bb1, bb2, e1, e2, phi, arg0, arg1);
+ {
+ phi = phi_nodes (bb2);
+
+ /* Check to make sure that there is only one PHI node.
+ TODO: we could do it with more than one iff the other PHI nodes
+ have the same elements for these two edges. */
+ if (!phi || PHI_CHAIN (phi) != NULL)
+ continue;
+
+ arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx);
+ arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx);
+
+ /* Something is wrong if we cannot find the arguments in the PHI
+ node. */
+ gcc_assert (arg0 != NULL && arg1 != NULL);
+
+ /* Do the replacement of conditional if it can be done. */
+ if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+ cfgchanged = true;
+ else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+ cfgchanged = true;
+ else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+ cfgchanged = true;
+ else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+ cfgchanged = true;
+ }
}
free (bb_order);
+
+ if (do_store_elim)
+ pointer_set_destroy (nontrap);
+ /* If the CFG has changed, we should cleanup the CFG. */
+ if (cfgchanged && do_store_elim)
+ {
+ /* In cond-store replacement we have added some loads on edges
+ and new VOPS (as we moved the store, and created a load). */
+ bsi_commit_edge_inserts ();
+ return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
+ }
+ else if (cfgchanged)
+ return TODO_cleanup_cfg;
+ return 0;
}
/* Returns the list of basic blocks in the function in an order that guarantees
that if a block X has just a single predecessor Y, then Y is after X in the
ordering. */
-static basic_block *
+basic_block *
blocks_in_phiopt_order (void)
{
basic_block x, y;
- basic_block *order = xmalloc (sizeof (basic_block) * n_basic_blocks);
- unsigned n = n_basic_blocks, np, i;
- sbitmap visited = sbitmap_alloc (last_basic_block + 2);
+ basic_block *order = XNEWVEC (basic_block, n_basic_blocks);
+ unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS;
+ unsigned np, i;
+ sbitmap visited = sbitmap_alloc (last_basic_block);
-#define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index + 2))
-#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index + 2))
+#define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index))
+#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index))
sbitmap_zero (visited);
#undef VISITED_P
}
+
/* Return TRUE if block BB has no executable statements, otherwise return
FALSE. */
+
bool
empty_block_p (basic_block bb)
{
return true;
}
-/* Replace PHI node element whoes edge is E in block BB with variable NEW.
+/* Replace PHI node element whose edge is E in block BB with variable NEW.
Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
is known to have two edges, one of which must reach BB). */
static void
-replace_phi_edge_with_variable (basic_block cond_block, basic_block bb,
- edge e, tree phi, tree new)
+replace_phi_edge_with_variable (basic_block cond_block,
+ edge e, tree phi, tree new_tree)
{
+ basic_block bb = bb_for_stmt (phi);
basic_block block_to_remove;
block_stmt_iterator bsi;
/* Change the PHI argument to new. */
- SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new);
+ SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
/* Remove the empty basic block. */
if (EDGE_SUCC (cond_block, 0)->dest == bb)
{
EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU;
EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
+ EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE;
+ EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count;
block_to_remove = EDGE_SUCC (cond_block, 1)->dest;
}
EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;
EDGE_SUCC (cond_block, 1)->flags
&= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
+ EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE;
+ EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count;
block_to_remove = EDGE_SUCC (cond_block, 0)->dest;
}
/* Eliminate the COND_EXPR at the end of COND_BLOCK. */
bsi = bsi_last (cond_block);
- bsi_remove (&bsi);
+ bsi_remove (&bsi, true);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file,
static bool
conditional_replacement (basic_block cond_bb, basic_block middle_bb,
- basic_block phi_bb, edge e0, edge e1, tree phi,
+ edge e0, edge e1, tree phi,
tree arg0, tree arg1)
{
tree result;
tree old_result = NULL;
- tree new, cond;
+ tree new_stmt, cond;
block_stmt_iterator bsi;
edge true_edge, false_edge;
tree new_var = NULL;
tree new_var1;
+ /* FIXME: Gimplification of complex type is too hard for now. */
+ if (TREE_CODE (TREE_TYPE (arg0)) == COMPLEX_TYPE
+ || TREE_CODE (TREE_TYPE (arg1)) == COMPLEX_TYPE)
+ return false;
+
/* The PHI arguments have the constants 0 and 1, then convert
it to the conditional. */
if ((integer_zerop (arg0) && integer_onep (arg1))
cond = COND_EXPR_COND (last_stmt (cond_bb));
result = PHI_RESULT (phi);
if (TREE_CODE (cond) != SSA_NAME
- && !lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result)))
+ && !useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (cond)))
{
- new_var = make_rename_temp (TREE_TYPE (cond), NULL);
+ tree tmp;
+
+ if (!COMPARISON_CLASS_P (cond))
+ return false;
+
+ tmp = create_tmp_var (TREE_TYPE (cond), NULL);
+ add_referenced_var (tmp);
+ new_var = make_ssa_name (tmp, NULL);
old_result = cond;
cond = new_var;
}
/* If the condition was a naked SSA_NAME and the type is not the
same as the type of the result, then convert the type of the
condition. */
- if (!lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result)))
+ if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (cond)))
cond = fold_convert (TREE_TYPE (result), cond);
/* We need to know which is the true edge and which is the false
if (old_result)
{
tree new1;
- if (!COMPARISON_CLASS_P (old_result))
- return false;
new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result),
TREE_OPERAND (old_result, 0),
TREE_OPERAND (old_result, 1));
- new1 = build2 (MODIFY_EXPR, TREE_TYPE (old_result), new_var, new1);
+ new1 = build_gimple_modify_stmt (new_var, new1);
+ SSA_NAME_DEF_STMT (new_var) = new1;
+
bsi_insert_after (&bsi, new1, BSI_NEW_STMT);
}
|| (e1 == true_edge && integer_onep (arg1))
|| (e1 == false_edge && integer_zerop (arg1)))
{
- new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond);
+ new_stmt = build_gimple_modify_stmt (new_var1, cond);
}
else
{
tree cond1 = invert_truthvalue (cond);
cond = cond1;
+
/* If what we get back is a conditional expression, there is no
way that it can be gimple. */
if (TREE_CODE (cond) == COND_EXPR)
return false;
}
+ /* If COND is not something we can expect to be reducible to a GIMPLE
+ condition, return early. */
+ if (is_gimple_cast (cond))
+ cond1 = TREE_OPERAND (cond, 0);
+ if (TREE_CODE (cond1) == TRUTH_NOT_EXPR
+ && !is_gimple_val (TREE_OPERAND (cond1, 0)))
+ {
+ release_ssa_name (new_var1);
+ return false;
+ }
+
/* If what we get back is not gimple try to create it as gimple by
using a temporary variable. */
if (is_gimple_cast (cond)
&& !is_gimple_val (TREE_OPERAND (cond, 0)))
{
- tree temp = TREE_OPERAND (cond, 0);
- tree new_var_1 = make_rename_temp (TREE_TYPE (temp), NULL);
- new = build2 (MODIFY_EXPR, TREE_TYPE (new_var_1), new_var_1, temp);
- bsi_insert_after (&bsi, new, BSI_NEW_STMT);
- cond = fold_convert (TREE_TYPE (result), new_var_1);
- }
-
- if (TREE_CODE (cond) == TRUTH_NOT_EXPR
- && !is_gimple_val (TREE_OPERAND (cond, 0)))
- {
- release_ssa_name (new_var1);
- return false;
+ tree op0, tmp, cond_tmp;
+
+ /* Only "real" casts are OK here, not everything that is
+ acceptable to is_gimple_cast. Make sure we don't do
+ anything stupid here. */
+ gcc_assert (TREE_CODE (cond) == NOP_EXPR
+ || TREE_CODE (cond) == CONVERT_EXPR);
+
+ op0 = TREE_OPERAND (cond, 0);
+ tmp = create_tmp_var (TREE_TYPE (op0), NULL);
+ add_referenced_var (tmp);
+ cond_tmp = make_ssa_name (tmp, NULL);
+ new_stmt = build_gimple_modify_stmt (cond_tmp, op0);
+ SSA_NAME_DEF_STMT (cond_tmp) = new_stmt;
+
+ bsi_insert_after (&bsi, new_stmt, BSI_NEW_STMT);
+ cond = fold_convert (TREE_TYPE (result), cond_tmp);
}
- new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond);
+ new_stmt = build_gimple_modify_stmt (new_var1, cond);
}
- bsi_insert_after (&bsi, new, BSI_NEW_STMT);
+ bsi_insert_after (&bsi, new_stmt, BSI_NEW_STMT);
- SSA_NAME_DEF_STMT (new_var1) = new;
+ SSA_NAME_DEF_STMT (new_var1) = new_stmt;
- replace_phi_edge_with_variable (cond_bb, phi_bb, e1, phi, new_var1);
+ replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1);
/* Note that we optimized this PHI. */
return true;
static bool
value_replacement (basic_block cond_bb, basic_block middle_bb,
- basic_block phi_bb, edge e0, edge e1, tree phi,
+ edge e0, edge e1, tree phi,
tree arg0, tree arg1)
{
tree cond;
else
arg = arg1;
- replace_phi_edge_with_variable (cond_bb, phi_bb, e1, phi, arg);
+ replace_phi_edge_with_variable (cond_bb, e1, phi, arg);
/* Note that we optimized this PHI. */
return true;
static bool
minmax_replacement (basic_block cond_bb, basic_block middle_bb,
- basic_block phi_bb, edge e0, edge e1, tree phi,
+ edge e0, edge e1, tree phi,
tree arg0, tree arg1)
{
tree result, type;
- tree cond, new;
+ tree cond, new_stmt;
edge true_edge, false_edge;
enum tree_code cmp, minmax, ass_code;
tree smaller, larger, arg_true, arg_false;
tree lhs, rhs, op0, op1, bound;
if (!assign
- || TREE_CODE (assign) != MODIFY_EXPR)
+ || TREE_CODE (assign) != GIMPLE_MODIFY_STMT)
return false;
- lhs = TREE_OPERAND (assign, 0);
- rhs = TREE_OPERAND (assign, 1);
+ lhs = GIMPLE_STMT_OPERAND (assign, 0);
+ rhs = GIMPLE_STMT_OPERAND (assign, 1);
ass_code = TREE_CODE (rhs);
if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
return false;
return false;
/* We need BOUND <= LARGER. */
- if (!integer_nonzerop (fold (build2 (LE_EXPR, boolean_type_node,
- bound, larger))))
+ if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
+ bound, larger)))
return false;
}
else if (operand_equal_for_phi_arg_p (arg_false, smaller))
return false;
/* We need BOUND >= SMALLER. */
- if (!integer_nonzerop (fold (build2 (GE_EXPR, boolean_type_node,
- bound, smaller))))
+ if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
+ bound, smaller)))
return false;
}
else
return false;
/* We need BOUND >= LARGER. */
- if (!integer_nonzerop (fold (build2 (GE_EXPR, boolean_type_node,
- bound, larger))))
+ if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
+ bound, larger)))
return false;
}
else if (operand_equal_for_phi_arg_p (arg_true, smaller))
return false;
/* We need BOUND <= SMALLER. */
- if (!integer_nonzerop (fold (build2 (LE_EXPR, boolean_type_node,
- bound, smaller))))
+ if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
+ bound, smaller)))
return false;
}
else
/* Emit the statement to compute min/max. */
result = duplicate_ssa_name (PHI_RESULT (phi), NULL);
- new = build2 (MODIFY_EXPR, type, result,
- build2 (minmax, type, arg0, arg1));
- SSA_NAME_DEF_STMT (result) = new;
+ new_stmt = build_gimple_modify_stmt (result, build2 (minmax, type, arg0, arg1));
+ SSA_NAME_DEF_STMT (result) = new_stmt;
bsi = bsi_last (cond_bb);
- bsi_insert_before (&bsi, new, BSI_NEW_STMT);
+ bsi_insert_before (&bsi, new_stmt, BSI_NEW_STMT);
- replace_phi_edge_with_variable (cond_bb, phi_bb, e1, phi, result);
+ replace_phi_edge_with_variable (cond_bb, e1, phi, result);
return true;
}
static bool
abs_replacement (basic_block cond_bb, basic_block middle_bb,
- basic_block phi_bb, edge e0 ATTRIBUTE_UNUSED, edge e1,
+ edge e0 ATTRIBUTE_UNUSED, edge e1,
tree phi, tree arg0, tree arg1)
{
tree result;
- tree new, cond;
+ tree new_stmt, cond;
block_stmt_iterator bsi;
edge true_edge, false_edge;
tree assign;
/* If we got here, then we have found the only executable statement
in OTHER_BLOCK. If it is anything other than arg = -arg1 or
arg1 = -arg0, then we can not optimize. */
- if (TREE_CODE (assign) != MODIFY_EXPR)
+ if (TREE_CODE (assign) != GIMPLE_MODIFY_STMT)
return false;
- lhs = TREE_OPERAND (assign, 0);
- rhs = TREE_OPERAND (assign, 1);
+ lhs = GIMPLE_STMT_OPERAND (assign, 0);
+ rhs = GIMPLE_STMT_OPERAND (assign, 1);
if (TREE_CODE (rhs) != NEGATE_EXPR)
return false;
result = duplicate_ssa_name (result, NULL);
if (negate)
- lhs = make_rename_temp (TREE_TYPE (result), NULL);
+ {
+ tree tmp = create_tmp_var (TREE_TYPE (result), NULL);
+ add_referenced_var (tmp);
+ lhs = make_ssa_name (tmp, NULL);
+ }
else
lhs = result;
/* Build the modify expression with abs expression. */
- new = build2 (MODIFY_EXPR, TREE_TYPE (lhs),
- lhs, build1 (ABS_EXPR, TREE_TYPE (lhs), rhs));
+ new_stmt = build_gimple_modify_stmt (lhs,
+ build1 (ABS_EXPR, TREE_TYPE (lhs), rhs));
+ SSA_NAME_DEF_STMT (lhs) = new_stmt;
bsi = bsi_last (cond_bb);
- bsi_insert_before (&bsi, new, BSI_NEW_STMT);
+ bsi_insert_before (&bsi, new_stmt, BSI_NEW_STMT);
if (negate)
{
/* Get the right BSI. We want to insert after the recently
added ABS_EXPR statement (which we know is the first statement
in the block. */
- new = build2 (MODIFY_EXPR, TREE_TYPE (result),
- result, build1 (NEGATE_EXPR, TREE_TYPE (lhs), lhs));
+ new_stmt = build_gimple_modify_stmt (result,
+ build1 (NEGATE_EXPR, TREE_TYPE (lhs),
+ lhs));
+ SSA_NAME_DEF_STMT (result) = new_stmt;
- bsi_insert_after (&bsi, new, BSI_NEW_STMT);
+ bsi_insert_after (&bsi, new_stmt, BSI_NEW_STMT);
}
- SSA_NAME_DEF_STMT (result) = new;
- replace_phi_edge_with_variable (cond_bb, phi_bb, e1, phi, result);
+ replace_phi_edge_with_variable (cond_bb, e1, phi, result);
/* Note that we optimized this PHI. */
return true;
}
+/* Auxiliary functions to determine the set of memory accesses which
+ can't trap because they are preceded by accesses to the same memory
+ portion. We do that for INDIRECT_REFs, so we only need to track
+ the SSA_NAME of the pointer indirectly referenced. The algorithm
+ simply is a walk over all instructions in dominator order. When
+ we see an INDIRECT_REF we determine if we've already seen a same
+ ref anywhere up to the root of the dominator tree. If we do the
+ current access can't trap. If we don't see any dominating access
+ the current access might trap, but might also make later accesses
+ non-trapping, so we remember it. We need to be careful with loads
+ or stores, for instance a load might not trap, while a store would,
+ so if we see a dominating read access this doesn't mean that a later
+ write access would not trap. Hence we also need to differentiate the
+ type of access(es) seen.
+
+ ??? We currently are very conservative and assume that a load might
+ trap even if a store doesn't (write-only memory). This probably is
+ overly conservative. */
+
+/* A hash-table of SSA_NAMEs, and in which basic block an INDIRECT_REF
+ through it was seen, which would constitute a no-trap region for
+ same accesses. */
+struct name_to_bb
+{
+ tree ssa_name;
+ basic_block bb;
+ unsigned store : 1;
+};
+
+/* The hash table for remembering what we've seen. */
+static htab_t seen_ssa_names;
+
+/* The set of INDIRECT_REFs which can't trap. */
+static struct pointer_set_t *nontrap_set;
+
+/* The hash function, based on the pointer to the pointer SSA_NAME. */
+static hashval_t
+name_to_bb_hash (const void *p)
+{
+ tree n = ((struct name_to_bb *)p)->ssa_name;
+ return htab_hash_pointer (n) ^ ((struct name_to_bb *)p)->store;
+}
+
+/* The equality function of *P1 and *P2. SSA_NAMEs are shared, so
+ it's enough to simply compare them for equality. */
+static int
+name_to_bb_eq (const void *p1, const void *p2)
+{
+ const struct name_to_bb *n1 = (const struct name_to_bb *)p1;
+ const struct name_to_bb *n2 = (const struct name_to_bb *)p2;
+
+ return n1->ssa_name == n2->ssa_name && n1->store == n2->store;
+}
+
+/* We see a the expression EXP in basic block BB. If it's an interesting
+ expression (an INDIRECT_REF through an SSA_NAME) possibly insert the
+ expression into the set NONTRAP or the hash table of seen expressions.
+ STORE is true if this expression is on the LHS, otherwise it's on
+ the RHS. */
+static void
+add_or_mark_expr (basic_block bb, tree exp,
+ struct pointer_set_t *nontrap, bool store)
+{
+ if (INDIRECT_REF_P (exp)
+ && TREE_CODE (TREE_OPERAND (exp, 0)) == SSA_NAME)
+ {
+ tree name = TREE_OPERAND (exp, 0);
+ struct name_to_bb map;
+ void **slot;
+ struct name_to_bb *n2bb;
+ basic_block found_bb = 0;
+
+ /* Try to find the last seen INDIRECT_REF through the same
+ SSA_NAME, which can trap. */
+ map.ssa_name = name;
+ map.bb = 0;
+ map.store = store;
+ slot = htab_find_slot (seen_ssa_names, &map, INSERT);
+ n2bb = (struct name_to_bb *) *slot;
+ if (n2bb)
+ found_bb = n2bb->bb;
+
+ /* If we've found a trapping INDIRECT_REF, _and_ it dominates EXP
+ (it's in a basic block on the path from us to the dominator root)
+ then we can't trap. */
+ if (found_bb && found_bb->aux == (void *)1)
+ {
+ pointer_set_insert (nontrap, exp);
+ }
+ else
+ {
+ /* EXP might trap, so insert it into the hash table. */
+ if (n2bb)
+ {
+ n2bb->bb = bb;
+ }
+ else
+ {
+ n2bb = XNEW (struct name_to_bb);
+ n2bb->ssa_name = name;
+ n2bb->bb = bb;
+ n2bb->store = store;
+ *slot = n2bb;
+ }
+ }
+ }
+}
+
+/* Called by walk_dominator_tree, when entering the block BB. */
+static void
+nt_init_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb)
+{
+ block_stmt_iterator bsi;
+ /* Mark this BB as being on the path to dominator root. */
+ bb->aux = (void*)1;
+
+ /* And walk the statements in order. */
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ {
+ tree stmt = bsi_stmt (bsi);
+
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+ {
+ tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+ add_or_mark_expr (bb, rhs, nontrap_set, false);
+ add_or_mark_expr (bb, lhs, nontrap_set, true);
+ }
+ }
+}
+
+/* Called by walk_dominator_tree, when basic block BB is exited. */
+static void
+nt_fini_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb)
+{
+ /* This BB isn't on the path to dominator root anymore. */
+ bb->aux = NULL;
+}
+
+/* This is the entry point of gathering non trapping memory accesses.
+ It will do a dominator walk over the whole function, and it will
+ make use of the bb->aux pointers. It returns a set of trees
+ (the INDIRECT_REFs itself) which can't trap. */
+static struct pointer_set_t *
+get_non_trapping (void)
+{
+ struct pointer_set_t *nontrap;
+ struct dom_walk_data walk_data;
+
+ nontrap = pointer_set_create ();
+ seen_ssa_names = htab_create (128, name_to_bb_hash, name_to_bb_eq,
+ free);
+ /* We're going to do a dominator walk, so ensure that we have
+ dominance information. */
+ calculate_dominance_info (CDI_DOMINATORS);
+
+ /* Setup callbacks for the generic dominator tree walker. */
+ nontrap_set = nontrap;
+ walk_data.walk_stmts_backward = false;
+ walk_data.dom_direction = CDI_DOMINATORS;
+ walk_data.initialize_block_local_data = NULL;
+ walk_data.before_dom_children_before_stmts = nt_init_block;
+ walk_data.before_dom_children_walk_stmts = NULL;
+ walk_data.before_dom_children_after_stmts = NULL;
+ walk_data.after_dom_children_before_stmts = NULL;
+ walk_data.after_dom_children_walk_stmts = NULL;
+ walk_data.after_dom_children_after_stmts = nt_fini_block;
+ walk_data.global_data = NULL;
+ walk_data.block_local_data_size = 0;
+ walk_data.interesting_blocks = NULL;
+
+ init_walk_dominator_tree (&walk_data);
+ walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+ fini_walk_dominator_tree (&walk_data);
+ htab_delete (seen_ssa_names);
+
+ return nontrap;
+}
+
+/* Do the main work of conditional store replacement. We already know
+ that the recognized pattern looks like so:
+
+ split:
+ if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
+ MIDDLE_BB:
+ something
+ fallthrough (edge E0)
+ JOIN_BB:
+ some more
+
+ We check that MIDDLE_BB contains only one store, that that store
+ doesn't trap (not via NOTRAP, but via checking if an access to the same
+ memory location dominates us) and that the store has a "simple" RHS. */
+
+static bool
+cond_store_replacement (basic_block middle_bb, basic_block join_bb,
+ edge e0, edge e1, struct pointer_set_t *nontrap)
+{
+ tree assign = last_and_only_stmt (middle_bb);
+ tree lhs, rhs, newexpr, name;
+ tree newphi;
+ block_stmt_iterator bsi;
+
+ /* Check if middle_bb contains of only one store. */
+ if (!assign
+ || TREE_CODE (assign) != GIMPLE_MODIFY_STMT)
+ return false;
+
+ lhs = GIMPLE_STMT_OPERAND (assign, 0);
+ if (!INDIRECT_REF_P (lhs))
+ return false;
+ rhs = GIMPLE_STMT_OPERAND (assign, 1);
+ if (TREE_CODE (rhs) != SSA_NAME && !is_gimple_min_invariant (rhs))
+ return false;
+ /* Prove that we can move the store down. We could also check
+ TREE_THIS_NOTRAP here, but in that case we also could move stores,
+ whose value is not available readily, which we want to avoid. */
+ if (!pointer_set_contains (nontrap, lhs))
+ return false;
+
+ /* Now we've checked the constraints, so do the transformation:
+ 1) Remove the single store. */
+ mark_symbols_for_renaming (assign);
+ bsi = bsi_for_stmt (assign);
+ bsi_remove (&bsi, true);
+
+ /* 2) Create a temporary where we can store the old content
+ of the memory touched by the store, if we need to. */
+ if (!condstoretemp || TREE_TYPE (lhs) != TREE_TYPE (condstoretemp))
+ {
+ condstoretemp = create_tmp_var (TREE_TYPE (lhs), "cstore");
+ get_var_ann (condstoretemp);
+ if (TREE_CODE (TREE_TYPE (lhs)) == COMPLEX_TYPE
+ || TREE_CODE (TREE_TYPE (lhs)) == VECTOR_TYPE)
+ DECL_GIMPLE_REG_P (condstoretemp) = 1;
+ }
+ add_referenced_var (condstoretemp);
+
+ /* 3) Insert a load from the memory of the store to the temporary
+ on the edge which did not contain the store. */
+ lhs = unshare_expr (lhs);
+ newexpr = build_gimple_modify_stmt (condstoretemp, lhs);
+ name = make_ssa_name (condstoretemp, newexpr);
+ GIMPLE_STMT_OPERAND (newexpr, 0) = name;
+ mark_symbols_for_renaming (newexpr);
+ bsi_insert_on_edge (e1, newexpr);
+
+ /* 4) Create a PHI node at the join block, with one argument
+ holding the old RHS, and the other holding the temporary
+ where we stored the old memory contents. */
+ newphi = create_phi_node (condstoretemp, join_bb);
+ add_phi_arg (newphi, rhs, e0);
+ add_phi_arg (newphi, name, e1);
+
+ lhs = unshare_expr (lhs);
+ newexpr = build_gimple_modify_stmt (lhs, PHI_RESULT (newphi));
+ mark_symbols_for_renaming (newexpr);
+
+ /* 5) Insert that PHI node. */
+ bsi = bsi_start (join_bb);
+ while (!bsi_end_p (bsi) && TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
+ bsi_next (&bsi);
+ if (bsi_end_p (bsi))
+ {
+ bsi = bsi_last (join_bb);
+ bsi_insert_after (&bsi, newexpr, BSI_NEW_STMT);
+ }
+ else
+ bsi_insert_before (&bsi, newexpr, BSI_NEW_STMT);
+
+ return true;
+}
/* Always do these optimizations if we have SSA
trees to work on. */
return 1;
}
-struct tree_opt_pass pass_phiopt =
+struct gimple_opt_pass pass_phiopt =
{
+ {
+ GIMPLE_PASS,
"phiopt", /* name */
gate_phiopt, /* gate */
tree_ssa_phiopt, /* execute */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_cleanup_cfg
- | TODO_dump_func
+ TODO_dump_func
+ | TODO_ggc_collect
+ | TODO_verify_ssa
+ | TODO_verify_flow
+ | TODO_verify_stmts /* todo_flags_finish */
+ }
+};
+
+static bool
+gate_cselim (void)
+{
+ return flag_tree_cselim;
+}
+
+struct gimple_opt_pass pass_cselim =
+{
+ {
+ GIMPLE_PASS,
+ "cselim", /* name */
+ gate_cselim, /* gate */
+ tree_ssa_cs_elim, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_TREE_PHIOPT, /* tv_id */
+ PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func
| TODO_ggc_collect
| TODO_verify_ssa
- | TODO_update_ssa
| TODO_verify_flow
- | TODO_verify_stmts, /* todo_flags_finish */
- 0 /* letter */
+ | TODO_verify_stmts /* todo_flags_finish */
+ }
};
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