/* 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 abs_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,
edge, edge, tree, tree, tree);
-static void replace_phi_edge_with_variable (basic_block, basic_block, edge,
- tree, tree);
+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), ...>;
+
+ with
+
+ bb0:
+ x' = cond;
+ goto bb2;
+ bb2:
+ x = PHI <x' (bb0), ...>;
+
+ We remove bb1 as it becomes unreachable. This occurs often due to
+ gimplification of conditionals.
+
+ Value Replacement
+ -----------------
- We can rewrite that as:
+ This transformation, implemented in value_replacement, replaces
bb0:
+ if (a != b) goto bb2; else goto bb1;
bb1:
bb2:
- x = cond;
+ x = PHI <a (bb1), b (bb0), ...>;
- 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.
+ with
- Also done is the following optimization:
+ bb0:
+ bb2:
+ x = PHI <b (bb0), ...>;
+
+ This opportunity can sometimes occur as a result of other
+ optimizations.
+
+ ABS Replacement
+ ---------------
+
+ This transformation, implemented in abs_replacement, replaces
bb0:
- if (a != b) goto bb2; else goto bb1;
+ if (a >= 0) goto bb2; else goto bb1;
bb1:
+ x = -a;
bb2:
- x = PHI (a (bb1), b (bb0))
+ x = PHI <x (bb1), a (bb0), ...>;
- We can rewrite that as:
+ with
bb0:
+ x' = ABS_EXPR< a >;
+ bb2:
+ x = PHI <x' (bb0), ...>;
+
+ MIN/MAX Replacement
+ -------------------
+
+ This transformation, minmax_replacement replaces
+
+ bb0:
+ if (a <= b) goto bb2; else goto bb1;
bb1:
bb2:
- x = b;
+ x = PHI <b (bb1), a (bb0), ...>;
+
+ with
+
+ bb0:
+ x' = MIN_EXPR (a, b)
+ bb2:
+ x = PHI <x' (bb0), ...>;
- This can sometimes occur as a result of other optimizations. A
- similar transformation is done by the ifcvt RTL optimizer.
+ A similar transformation is done for MAX_EXPR. */
+
+static unsigned int
+tree_ssa_phiopt (void)
+{
+ return tree_ssa_phiopt_worker (false);
+}
- This pass also eliminates PHI nodes which are really absolute
- values. i.e. if we have something like:
+/* 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 (a >= 0) goto bb2; else goto bb1;
+ if (cond) goto bb2; else goto bb1;
bb1:
- x = -a;
+ *p = RHS
bb2:
- x = PHI (x (bb1), a (bb0));
- We can rewrite that as:
+ with
bb0:
+ if (cond) goto bb1; else goto bb2;
bb1:
+ condtmp' = *p;
bb2:
- x = ABS_EXPR< a >;
+ condtmp = PHI <RHS, condtmp'>
+ *p = condtmp
- 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. */
+ This transformation can only be done under several constraints,
+ documented below. */
-static void
-tree_ssa_phiopt (void)
+static unsigned int
+tree_ssa_cs_elim (void)
+{
+ return tree_ssa_phiopt_worker (true);
+}
+
+/* For conditional store replacement we need a temporary to
+ put the old contents of the memory in. */
+static tree condstoretemp;
+
+/* 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;
- bool removed_phis = false;
+ basic_block *bb_order;
+ unsigned n, i;
+ bool cfgchanged = false;
+ struct pointer_set_t *nontrap = 0;
- /* Search every basic block for COND_EXPR we may be able to optimize
- in reverse order so we can find more. */
- FOR_EACH_BB_REVERSE (bb)
+ 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.
+
+ We walk the blocks in order that guarantees that a block with
+ a single predecessor is processed before the predecessor.
+ This ensures that we collapse inner ifs before visiting the
+ outer ones, and also that we do not try to visit a removed
+ block. */
+ bb_order = blocks_in_phiopt_order ();
+ n = n_basic_blocks - NUM_FIXED_BLOCKS;
+
+ for (i = 0; i < n; i++)
{
tree cond_expr;
tree phi;
basic_block bb1, bb2;
edge e1, e2;
+ tree arg0, arg1;
+
+ bb = bb_order[i];
cond_expr = last_stmt (bb);
/* Check to see if the last statement is a COND_EXPR. */
continue;
/* If either bb1's succ or bb2 or bb2's succ is non NULL. */
- if (EDGE_COUNT (bb1->succs) < 1
+ if (EDGE_COUNT (bb1->succs) == 0
|| bb2 == NULL
- || EDGE_COUNT (bb2->succs) < 1)
+ || EDGE_COUNT (bb2->succs) == 0)
continue;
/* Find the bb which is the fall through to the other. */
e1 = EDGE_SUCC (bb1, 0);
/* Make sure that bb1 is just a fall through. */
- if (EDGE_COUNT (bb1->succs) > 1
+ if (!single_succ_p (bb1)
|| (e1->flags & EDGE_FALLTHRU) == 0)
continue;
- /* Also make that bb1 only have one pred and it is bb. */
- if (EDGE_COUNT (bb1->preds) > 1
- || EDGE_PRED (bb1, 0)->src != 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)
+ if (do_store_elim)
{
- tree arg0 = NULL, arg1 = NULL;
- int i;
+ /* 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
+ {
+ 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
+ /* 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, bb2, e1, e2, phi, arg0, arg1)
- || value_replacement (bb, bb1, bb2, e1, e2, phi, arg0, arg1)
- || abs_replacement (bb, bb1, bb2, e1, e2, phi, arg0, arg1))
- {
- /* We have done the replacement so we need to rebuild the
- cfg when this pass is complete. */
- removed_phis = true;
- }
+ 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. */
+
+basic_block *
+blocks_in_phiopt_order (void)
+{
+ basic_block x, y;
+ 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))
+#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index))
+
+ sbitmap_zero (visited);
+
+ MARK_VISITED (ENTRY_BLOCK_PTR);
+ FOR_EACH_BB (x)
+ {
+ if (VISITED_P (x))
+ continue;
+
+ /* Walk the predecessors of x as long as they have precisely one
+ predecessor and add them to the list, so that they get stored
+ after x. */
+ for (y = x, np = 1;
+ single_pred_p (y) && !VISITED_P (single_pred (y));
+ y = single_pred (y))
+ np++;
+ for (y = x, i = n - np;
+ single_pred_p (y) && !VISITED_P (single_pred (y));
+ y = single_pred (y), i++)
+ {
+ order[i] = y;
+ MARK_VISITED (y);
+ }
+ order[i] = y;
+ MARK_VISITED (y);
+
+ gcc_assert (i == n - 1);
+ n -= np;
+ }
+
+ sbitmap_free (visited);
+ gcc_assert (n == 0);
+ return order;
+
+#undef MARK_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;
- int i;
block_stmt_iterator bsi;
/* Change the PHI argument to new. */
- PHI_ARG_DEF_TREE (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
edge so that we know when to invert the condition below. */
extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
- /* Insert our new statement at the end of condtional block before the
+ /* Insert our new statement at the end of conditional block before the
COND_EXPR. */
bsi = bsi_last (cond_bb);
bsi_insert_before (&bsi, build_empty_stmt (), BSI_NEW_STMT);
if (old_result)
{
tree new1;
- if (!COMPARISON_CLASS_P (old_result))
- return false;
- new1 = build (TREE_CODE (old_result), TREE_TYPE (old_result),
- TREE_OPERAND (old_result, 0),
- TREE_OPERAND (old_result, 1));
+ new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result),
+ TREE_OPERAND (old_result, 0),
+ TREE_OPERAND (old_result, 1));
+
+ new1 = build_gimple_modify_stmt (new_var, new1);
+ SSA_NAME_DEF_STMT (new_var) = new1;
- new1 = build (MODIFY_EXPR, TREE_TYPE (old_result), new_var, new1);
bsi_insert_after (&bsi, new1, BSI_NEW_STMT);
}
|| (e1 == true_edge && integer_onep (arg1))
|| (e1 == false_edge && integer_zerop (arg1)))
{
- new = build (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 = build (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 = build (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 result;
tree cond;
edge true_edge, false_edge;
return false;
cond = COND_EXPR_COND (last_stmt (cond_bb));
- result = PHI_RESULT (phi);
/* This transformation is only valid for equality comparisons. */
if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR)
edge from OTHER_BLOCK which reaches BB and represents the desired
path from COND_BLOCK. */
if (e->dest == middle_bb)
- e = EDGE_SUCC (e->dest, 0);
+ e = single_succ_edge (e->dest);
/* Now we know the incoming edge to BB that has the argument for the
RHS of our new assignment statement. */
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;
return false;
}
+/* The function minmax_replacement does the main work of doing the minmax
+ replacement. Return true if the replacement is done. Otherwise return
+ false.
+ BB is the basic block where the replacement is going to be done on. ARG0
+ is argument 0 from the PHI. Likewise for ARG1. */
+
+static bool
+minmax_replacement (basic_block cond_bb, basic_block middle_bb,
+ edge e0, edge e1, tree phi,
+ tree arg0, tree arg1)
+{
+ tree result, type;
+ tree cond, new_stmt;
+ edge true_edge, false_edge;
+ enum tree_code cmp, minmax, ass_code;
+ tree smaller, larger, arg_true, arg_false;
+ block_stmt_iterator bsi, bsi_from;
+
+ type = TREE_TYPE (PHI_RESULT (phi));
+
+ /* The optimization may be unsafe due to NaNs. */
+ if (HONOR_NANS (TYPE_MODE (type)))
+ return false;
+
+ cond = COND_EXPR_COND (last_stmt (cond_bb));
+ cmp = TREE_CODE (cond);
+ result = PHI_RESULT (phi);
+
+ /* This transformation is only valid for order comparisons. Record which
+ operand is smaller/larger if the result of the comparison is true. */
+ if (cmp == LT_EXPR || cmp == LE_EXPR)
+ {
+ smaller = TREE_OPERAND (cond, 0);
+ larger = TREE_OPERAND (cond, 1);
+ }
+ else if (cmp == GT_EXPR || cmp == GE_EXPR)
+ {
+ smaller = TREE_OPERAND (cond, 1);
+ larger = TREE_OPERAND (cond, 0);
+ }
+ else
+ return false;
+
+ /* We need to know which is the true edge and which is the false
+ edge so that we know if have abs or negative abs. */
+ extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
+
+ /* Forward the edges over the middle basic block. */
+ if (true_edge->dest == middle_bb)
+ true_edge = EDGE_SUCC (true_edge->dest, 0);
+ if (false_edge->dest == middle_bb)
+ false_edge = EDGE_SUCC (false_edge->dest, 0);
+
+ if (true_edge == e0)
+ {
+ gcc_assert (false_edge == e1);
+ arg_true = arg0;
+ arg_false = arg1;
+ }
+ else
+ {
+ gcc_assert (false_edge == e0);
+ gcc_assert (true_edge == e1);
+ arg_true = arg1;
+ arg_false = arg0;
+ }
+
+ if (empty_block_p (middle_bb))
+ {
+ if (operand_equal_for_phi_arg_p (arg_true, smaller)
+ && operand_equal_for_phi_arg_p (arg_false, larger))
+ {
+ /* Case
+
+ if (smaller < larger)
+ rslt = smaller;
+ else
+ rslt = larger; */
+ minmax = MIN_EXPR;
+ }
+ else if (operand_equal_for_phi_arg_p (arg_false, smaller)
+ && operand_equal_for_phi_arg_p (arg_true, larger))
+ minmax = MAX_EXPR;
+ else
+ return false;
+ }
+ else
+ {
+ /* Recognize the following case, assuming d <= u:
+
+ if (a <= u)
+ b = MAX (a, d);
+ x = PHI <b, u>
+
+ This is equivalent to
+
+ b = MAX (a, d);
+ x = MIN (b, u); */
+
+ tree assign = last_and_only_stmt (middle_bb);
+ tree lhs, rhs, op0, op1, bound;
+
+ if (!assign
+ || TREE_CODE (assign) != GIMPLE_MODIFY_STMT)
+ return false;
+
+ 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;
+ op0 = TREE_OPERAND (rhs, 0);
+ op1 = TREE_OPERAND (rhs, 1);
+
+ if (true_edge->src == middle_bb)
+ {
+ /* We got here if the condition is true, i.e., SMALLER < LARGER. */
+ if (!operand_equal_for_phi_arg_p (lhs, arg_true))
+ return false;
+
+ if (operand_equal_for_phi_arg_p (arg_false, larger))
+ {
+ /* Case
+
+ if (smaller < larger)
+ {
+ r' = MAX_EXPR (smaller, bound)
+ }
+ r = PHI <r', larger> --> to be turned to MIN_EXPR. */
+ if (ass_code != MAX_EXPR)
+ return false;
+
+ minmax = MIN_EXPR;
+ if (operand_equal_for_phi_arg_p (op0, smaller))
+ bound = op1;
+ else if (operand_equal_for_phi_arg_p (op1, smaller))
+ bound = op0;
+ else
+ return false;
+
+ /* We need 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))
+ {
+ /* Case
+
+ if (smaller < larger)
+ {
+ r' = MIN_EXPR (larger, bound)
+ }
+ r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
+ if (ass_code != MIN_EXPR)
+ return false;
+
+ minmax = MAX_EXPR;
+ if (operand_equal_for_phi_arg_p (op0, larger))
+ bound = op1;
+ else if (operand_equal_for_phi_arg_p (op1, larger))
+ bound = op0;
+ else
+ return false;
+
+ /* We need BOUND >= SMALLER. */
+ if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
+ bound, smaller)))
+ return false;
+ }
+ else
+ return false;
+ }
+ else
+ {
+ /* We got here if the condition is false, i.e., SMALLER > LARGER. */
+ if (!operand_equal_for_phi_arg_p (lhs, arg_false))
+ return false;
+
+ if (operand_equal_for_phi_arg_p (arg_true, larger))
+ {
+ /* Case
+
+ if (smaller > larger)
+ {
+ r' = MIN_EXPR (smaller, bound)
+ }
+ r = PHI <r', larger> --> to be turned to MAX_EXPR. */
+ if (ass_code != MIN_EXPR)
+ return false;
+
+ minmax = MAX_EXPR;
+ if (operand_equal_for_phi_arg_p (op0, smaller))
+ bound = op1;
+ else if (operand_equal_for_phi_arg_p (op1, smaller))
+ bound = op0;
+ else
+ return false;
+
+ /* We need 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))
+ {
+ /* Case
+
+ if (smaller > larger)
+ {
+ r' = MAX_EXPR (larger, bound)
+ }
+ r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
+ if (ass_code != MAX_EXPR)
+ return false;
+
+ minmax = MIN_EXPR;
+ if (operand_equal_for_phi_arg_p (op0, larger))
+ bound = op1;
+ else if (operand_equal_for_phi_arg_p (op1, larger))
+ bound = op0;
+ else
+ return false;
+
+ /* We need BOUND <= SMALLER. */
+ if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
+ bound, smaller)))
+ return false;
+ }
+ else
+ return false;
+ }
+
+ /* Move the statement from the middle block. */
+ bsi = bsi_last (cond_bb);
+ bsi_from = bsi_last (middle_bb);
+ bsi_move_before (&bsi_from, &bsi);
+ }
+
+ /* Emit the statement to compute min/max. */
+ result = duplicate_ssa_name (PHI_RESULT (phi), NULL);
+ 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_stmt, BSI_NEW_STMT);
+
+ replace_phi_edge_with_variable (cond_bb, e1, phi, result);
+ return true;
+}
+
/* The function absolute_replacement does the main work of doing the absolute
replacement. Return true if the replacement is done. Otherwise return
false.
bb is the basic block where the replacement is going to be done on. arg0
- is argument 0 from the phi. Likewise for arg1. */
+ is argument 0 from the phi. Likewise for arg1. */
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 = NULL;
+ tree assign;
edge e;
- tree rhs = NULL, lhs = NULL;
+ tree rhs, lhs;
bool negate;
enum tree_code cond_code;
/* OTHER_BLOCK must have only one executable statement which must have the
form arg0 = -arg1 or arg1 = -arg0. */
- bsi = bsi_start (middle_bb);
- while (!bsi_end_p (bsi))
- {
- tree stmt = bsi_stmt (bsi);
-
- /* Empty statements and labels are uninteresting. */
- if (TREE_CODE (stmt) == LABEL_EXPR
- || IS_EMPTY_STMT (stmt))
- {
- bsi_next (&bsi);
- continue;
- }
-
- /* If we found the assignment, but it was not the only executable
- statement in OTHER_BLOCK, then we can not optimize. */
- if (assign)
- return false;
-
- /* If we got here, then we have found the first executable statement
- in OTHER_BLOCK. If it is anything other than arg = -arg1 or
- arg1 = -arg0, then we can not optimize. */
- if (TREE_CODE (stmt) == MODIFY_EXPR)
- {
- lhs = TREE_OPERAND (stmt, 0);
- rhs = TREE_OPERAND (stmt, 1);
-
- if (TREE_CODE (rhs) == NEGATE_EXPR)
- {
- rhs = TREE_OPERAND (rhs, 0);
-
- /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
- if ((lhs == arg0 && rhs == arg1)
- || (lhs == arg1 && rhs == arg0))
- {
- assign = stmt;
- bsi_next (&bsi);
- }
- else
- return false;
- }
- else
- return false;
- }
- else
- return false;
- }
+ assign = last_and_only_stmt (middle_bb);
/* If we did not find the proper negation assignment, then we can not
optimize. */
if (assign == NULL)
return false;
+
+ /* 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) != GIMPLE_MODIFY_STMT)
+ return false;
+
+ lhs = GIMPLE_STMT_OPERAND (assign, 0);
+ rhs = GIMPLE_STMT_OPERAND (assign, 1);
+
+ if (TREE_CODE (rhs) != NEGATE_EXPR)
+ return false;
+
+ rhs = TREE_OPERAND (rhs, 0);
+
+ /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
+ if (!(lhs == arg0 && rhs == arg1)
+ && !(lhs == arg1 && rhs == arg0))
+ return false;
cond = COND_EXPR_COND (last_stmt (cond_bb));
result = PHI_RESULT (phi);
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 = build (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 = build (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_ggc_collect /* todo_flags_finish */
- | TODO_verify_ssa | TODO_rename_vars
- | TODO_verify_flow | TODO_verify_stmts,
- 0 /* letter */
+ 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_verify_flow
+ | TODO_verify_stmts /* todo_flags_finish */
+ }
};
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