/* Optimization of PHI nodes by converting them into straightline code.
- Copyright (C) 2004 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005 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
later version.
-
+
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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. */
+Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA. */
#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 "langhooks.h"
static void tree_ssa_phiopt (void);
-static bool conditional_replacement (basic_block, tree, tree, tree);
-static bool value_replacement (basic_block, tree, tree, tree);
-static bool abs_replacement (basic_block, tree, tree, tree);
-static void replace_phi_with_stmt (block_stmt_iterator, basic_block,
- basic_block, tree, tree);
-static bool candidate_bb_for_phi_optimization (basic_block,
- basic_block *,
- basic_block *);
-static bool empty_block_p (basic_block);
-
-/* This pass eliminates PHI nodes which can be trivially implemented as
- an assignment from a conditional expression. ie if we have something
- like:
+static bool conditional_replacement (basic_block, basic_block,
+ edge, edge, tree, tree, tree);
+static bool value_replacement (basic_block, basic_block,
+ edge, edge, tree, tree, tree);
+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, edge, tree, tree);
+static basic_block *blocks_in_phiopt_order (void);
+
+/* 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
- We can rewrite that as:
-
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.
-
- Also done is the following optimization:
+ Value Replacement
+ -----------------
+
+ 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 can sometimes occur as a result of other optimizations. A
- similar transformation is done by the ifcvt RTL optimizer.
+ This opportunity can sometimes occur as a result of other
+ optimizations.
- This pass also eliminates PHI nodes which are really absolute
- values. i.e. if we have something like:
+ ABS Replacement
+ ---------------
+
+ 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));
+ 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 = ABS_EXPR< a >;
+ x = PHI <b (bb1), a (bb0), ...>;
+
+ with
+
+ bb0:
+ x' = MIN_EXPR (a, b)
+ bb2:
+ x = PHI <x' (bb0), ...>;
- 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. */
+ A similar transformation is done for MAX_EXPR. */
static void
tree_ssa_phiopt (void)
{
basic_block bb;
- bool removed_phis = false;
+ basic_block *bb_order;
+ unsigned n, i;
+
+ /* Search every basic block for COND_EXPR we may be able to optimize.
- /* Search every basic block for PHI nodes we may be able to optimize. */
- FOR_EACH_BB (bb)
+ 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;
+
+ for (i = 0; i < n; i++)
{
- tree arg0, arg1, phi;
+ 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. */
+ if (!cond_expr
+ || TREE_CODE (cond_expr) != COND_EXPR)
+ continue;
+
+ e1 = EDGE_SUCC (bb, 0);
+ bb1 = e1->dest;
+ e2 = EDGE_SUCC (bb, 1);
+ bb2 = e2->dest;
+
+ /* We cannot do the optimization on abnormal edges. */
+ if ((e1->flags & EDGE_ABNORMAL) != 0
+ || (e2->flags & EDGE_ABNORMAL) != 0)
+ continue;
+
+ /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
+ if (EDGE_COUNT (bb1->succs) == 0
+ || bb2 == NULL
+ || EDGE_COUNT (bb2->succs) == 0)
+ continue;
+
+ /* Find the bb which is the fall through to the other. */
+ if (EDGE_SUCC (bb1, 0)->dest == bb2)
+ ;
+ else if (EDGE_SUCC (bb2, 0)->dest == bb1)
+ {
+ basic_block bb_tmp = bb1;
+ edge e_tmp = e1;
+ bb1 = bb2;
+ bb2 = bb_tmp;
+ e1 = e2;
+ e2 = e_tmp;
+ }
+ else
+ continue;
+
+ e1 = EDGE_SUCC (bb1, 0);
+
+ /* Make sure that bb1 is just a fall through. */
+ if (!single_succ_p (bb1)
+ || (e1->flags & EDGE_FALLTHRU) == 0)
+ continue;
+
+ /* 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);
+
+ /* 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))
+ ;
+ else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+ ;
+ else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+ ;
+ else
+ minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1);
+ }
+
+ free (bb_order);
+}
+
+/* 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 *
+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);
- /* We're searching for blocks with one PHI node which has two
- arguments. */
- phi = phi_nodes (bb);
- if (phi && TREE_CHAIN (phi) == NULL
- && PHI_NUM_ARGS (phi) == 2)
+#define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index + 2))
+#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index + 2))
+
+ 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++)
{
- arg0 = PHI_ARG_DEF (phi, 0);
- arg1 = PHI_ARG_DEF (phi, 1);
-
- /* Do the replacement of conditional if it can be done. */
- if (conditional_replacement (bb, phi, arg0, arg1)
- || value_replacement (bb, phi, arg0, arg1)
- || abs_replacement (bb, phi, arg0, arg1))
- {
- /* We have done the replacement so we need to rebuild the
- cfg when this pass is complete. */
- removed_phis = true;
- }
+ order[i] = y;
+ MARK_VISITED (y);
}
+ order[i] = y;
+ MARK_VISITED (y);
+
+ gcc_assert (i == n - 1);
+ n -= np;
}
- /* If we removed any PHIs, then we have unreachable blocks and blocks
- which need to be merged in the CFG. */
- if (removed_phis)
- cleanup_tree_cfg ();
+ 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. */
-static bool
+bool
empty_block_p (basic_block bb)
{
block_stmt_iterator bsi;
&& (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR
|| IS_EMPTY_STMT (bsi_stmt (bsi))))
bsi_next (&bsi);
-
+
if (!bsi_end_p (bsi))
return false;
return true;
}
-/* BB is a basic block which has only one PHI node with precisely two
- arguments.
-
- Examine both of BB's predecessors to see if one ends with a
- COND_EXPR and the other is a successor of the COND_EXPR. If so, then
- we may be able to optimize PHI nodes at the start of BB.
-
- If so, mark store the block with the COND_EXPR into COND_BLOCK_P
- and the other block into OTHER_BLOCK_P and return true, otherwise
- return false. */
-
-static bool
-candidate_bb_for_phi_optimization (basic_block bb,
- basic_block *cond_block_p,
- basic_block *other_block_p)
-{
- tree last0, last1;
- basic_block cond_block, other_block;
-
- /* One of the alternatives must come from a block ending with
- a COND_EXPR. */
- last0 = last_stmt (bb->pred->src);
- last1 = last_stmt (bb->pred->pred_next->src);
- if (last0 && TREE_CODE (last0) == COND_EXPR)
- {
- cond_block = bb->pred->src;
- other_block = bb->pred->pred_next->src;
- }
- else if (last1 && TREE_CODE (last1) == COND_EXPR)
- {
- other_block = bb->pred->src;
- cond_block = bb->pred->pred_next->src;
- }
- else
- return false;
-
- /* COND_BLOCK must have precisely two successors. We indirectly
- verify that those successors are BB and OTHER_BLOCK. */
- if (!cond_block->succ
- || !cond_block->succ->succ_next
- || cond_block->succ->succ_next->succ_next
- || (cond_block->succ->flags & EDGE_ABNORMAL) != 0
- || (cond_block->succ->succ_next->flags & EDGE_ABNORMAL) != 0)
- return false;
-
- /* OTHER_BLOCK must have a single predecessor which is COND_BLOCK,
- OTHER_BLOCK must have a single successor which is BB and
- OTHER_BLOCK must have no PHI nodes. */
- if (!other_block->pred
- || other_block->pred->src != cond_block
- || other_block->pred->pred_next
- || !other_block->succ
- || other_block->succ->dest != bb
- || other_block->succ->succ_next
- || phi_nodes (other_block))
- return false;
-
- *cond_block_p = cond_block;
- *other_block_p = other_block;
- /* Everything looks OK. */
- return true;
-}
-
-/* Replace PHI in block BB with statement NEW. NEW is inserted after
- BSI. Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
+/* 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_with_stmt (block_stmt_iterator bsi, basic_block bb,
- basic_block cond_block, tree phi, tree new)
+replace_phi_edge_with_variable (basic_block cond_block,
+ edge e, tree phi, tree new)
{
- /* Insert our new statement at the head of our block. */
- bsi_insert_after (&bsi, new, BSI_NEW_STMT);
-
- /* Register our new statement as the defining statement for
- the result. */
- SSA_NAME_DEF_STMT (PHI_RESULT (phi)) = new;
-
- /* Remove the now useless PHI node.
-
- We do not want to use remove_phi_node since that releases the
- SSA_NAME as well and the SSA_NAME is still being used. */
- release_phi_node (phi);
- bb_ann (bb)->phi_nodes = NULL;
-
- /* Disconnect the edge leading into the empty block. That will
- make the empty block unreachable and it will be removed later. */
- if (cond_block->succ->dest == bb)
+ 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);
+
+ /* Remove the empty basic block. */
+ if (EDGE_SUCC (cond_block, 0)->dest == bb)
{
- cond_block->succ->flags |= EDGE_FALLTHRU;
- cond_block->succ->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
- ssa_remove_edge (cond_block->succ->succ_next);
+ 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;
}
else
{
- cond_block->succ->succ_next->flags |= EDGE_FALLTHRU;
- cond_block->succ->succ_next->flags
+ EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;
+ EDGE_SUCC (cond_block, 1)->flags
&= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
- ssa_remove_edge (cond_block->succ);
+ 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;
}
-
+ delete_basic_block (block_to_remove);
+
/* Eliminate the COND_EXPR at the end of COND_BLOCK. */
bsi = bsi_last (cond_block);
bsi_remove (&bsi);
-
+
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file,
"COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
conditional 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 PHI. Likewise for ARG1. */
+ is argument 0 from PHI. Likewise for ARG1. */
static bool
-conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
+conditional_replacement (basic_block cond_bb, basic_block middle_bb,
+ edge e0, edge e1, tree phi,
+ tree arg0, tree arg1)
{
tree result;
tree old_result = NULL;
- basic_block other_block = NULL;
- basic_block cond_block = NULL;
tree new, cond;
block_stmt_iterator bsi;
edge true_edge, false_edge;
tree new_var = NULL;
+ tree new_var1;
/* The PHI arguments have the constants 0 and 1, then convert
it to the conditional. */
;
else
return false;
-
- if (!candidate_bb_for_phi_optimization (bb, &cond_block, &other_block)
- || !empty_block_p (other_block))
+
+ if (!empty_block_p (middle_bb))
return false;
-
+
/* If the condition is not a naked SSA_NAME and its type does not
match the type of the result, then we have to create a new
variable to optimize this case as it would likely create
non-gimple code when the condition was converted to the
result's type. */
- cond = COND_EXPR_COND (last_stmt (cond_block));
+ 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)))
{
- 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_tmp_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)))
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_block, &true_edge, &false_edge);
-
- /* Insert our new statement at the head of our block. */
- bsi = bsi_start (bb);
-
+ extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
+
+ /* 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 (TREE_CODE_CLASS (TREE_CODE (old_result)) != '<')
- return false;
-
- new1 = build (TREE_CODE (old_result), TREE_TYPE (result),
- TREE_OPERAND (old_result, 0),
- TREE_OPERAND (old_result, 1));
-
- new1 = build (MODIFY_EXPR, TREE_TYPE (result), new_var, new1);
+
+ 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);
+ SSA_NAME_DEF_STMT (new_var) = new1;
+
bsi_insert_after (&bsi, new1, BSI_NEW_STMT);
}
-
+
+ new_var1 = duplicate_ssa_name (PHI_RESULT (phi), NULL);
+
+
/* At this point we know we have a COND_EXPR with two successors.
One successor is BB, the other successor is an empty block which
falls through into BB.
-
+
There is a single PHI node at the join point (BB) and its arguments
are constants (0, 1).
-
+
So, given the condition COND, and the two PHI arguments, we can
- rewrite this PHI into non-branching code:
-
+ rewrite this PHI into non-branching code:
+
dest = (COND) or dest = COND'
-
+
We use the condition as-is if the argument associated with the
true edge has the value one or the argument associated with the
false edge as the value zero. Note that those conditions are not
the same since only one of the outgoing edges from the COND_EXPR
will directly reach BB and thus be associated with an argument. */
- if ((PHI_ARG_EDGE (phi, 0) == true_edge && integer_onep (arg0))
- || (PHI_ARG_EDGE (phi, 0) == false_edge && integer_zerop (arg0))
- || (PHI_ARG_EDGE (phi, 1) == true_edge && integer_onep (arg1))
- || (PHI_ARG_EDGE (phi, 1) == false_edge && integer_zerop (arg1)))
+ if ((e0 == true_edge && integer_onep (arg0))
+ || (e0 == false_edge && integer_zerop (arg0))
+ || (e1 == true_edge && integer_onep (arg1))
+ || (e1 == false_edge && integer_zerop (arg1)))
{
- new = build (MODIFY_EXPR, TREE_TYPE (PHI_RESULT (phi)),
- PHI_RESULT (phi), cond);
+ new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), 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;
+ {
+ release_ssa_name (new_var1);
+ 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. */
+ 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);
+ 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_tmp_var (tmp);
+ cond_tmp = make_ssa_name (tmp, NULL);
+ new = build2 (MODIFY_EXPR, TREE_TYPE (cond_tmp), cond_tmp, op0);
+ SSA_NAME_DEF_STMT (cond_tmp) = new;
+
bsi_insert_after (&bsi, new, BSI_NEW_STMT);
- cond = fold_convert (TREE_TYPE (result), new_var_1);
+ cond = fold_convert (TREE_TYPE (result), cond_tmp);
}
-
- if (TREE_CODE (cond) == TRUTH_NOT_EXPR
- && !is_gimple_val (TREE_OPERAND (cond, 0)))
- return false;
- new = build (MODIFY_EXPR, TREE_TYPE (PHI_RESULT (phi)),
- PHI_RESULT (phi), cond);
+ new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond);
}
-
- replace_phi_with_stmt (bsi, bb, cond_block, phi, new);
+
+ bsi_insert_after (&bsi, new, BSI_NEW_STMT);
+
+ SSA_NAME_DEF_STMT (new_var1) = new;
+
+ replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1);
/* Note that we optimized this PHI. */
return true;
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
-value_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
+value_replacement (basic_block cond_bb, basic_block middle_bb,
+ edge e0, edge e1, tree phi,
+ tree arg0, tree arg1)
{
- tree result;
- basic_block other_block = NULL;
- basic_block cond_block = NULL;
- tree new, cond;
+ tree cond;
edge true_edge, false_edge;
/* If the type says honor signed zeros we cannot do this
- optimization. */
+ optimization. */
if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
return false;
- if (!candidate_bb_for_phi_optimization (bb, &cond_block, &other_block)
- || !empty_block_p (other_block))
+ if (!empty_block_p (middle_bb))
return false;
- cond = COND_EXPR_COND (last_stmt (cond_block));
- result = PHI_RESULT (phi);
+ cond = COND_EXPR_COND (last_stmt (cond_bb));
/* This transformation is only valid for equality comparisons. */
if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR)
/* 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_block, &true_edge, &false_edge);
+ extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
/* At this point we know we have a COND_EXPR with two successors.
One successor is BB, the other successor is an empty block which
We now need to verify that the two arguments in the PHI node match
the two arguments to the equality comparison. */
-
- if ((operand_equal_p (arg0, TREE_OPERAND (cond, 0), 0)
- && operand_equal_p (arg1, TREE_OPERAND (cond, 1), 0))
- || (operand_equal_p (arg1, TREE_OPERAND (cond, 0), 0)
- && operand_equal_p (arg0, TREE_OPERAND (cond, 1), 0)))
+
+ if ((operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 0))
+ && operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 1)))
+ || (operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 0))
+ && operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 1))))
{
edge e;
tree arg;
+ /* For NE_EXPR, we want to build an assignment result = arg where
+ arg is the PHI argument associated with the true edge. For
+ EQ_EXPR we want the PHI argument associated with the false edge. */
e = (TREE_CODE (cond) == NE_EXPR ? true_edge : false_edge);
- if (PHI_ARG_EDGE (phi, 0) == e)
+
+ /* Unfortunately, E may not reach BB (it may instead have gone to
+ OTHER_BLOCK). If that is the case, then we want the single outgoing
+ edge from OTHER_BLOCK which reaches BB and represents the desired
+ path from COND_BLOCK. */
+ if (e->dest == middle_bb)
+ 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. */
+ if (e0 == e)
arg = arg0;
else
arg = arg1;
- /* Build the new assignment. */
- new = build (MODIFY_EXPR, TREE_TYPE (result), result, arg);
-
- replace_phi_with_stmt (bsi_start (bb), bb, cond_block, phi, new);
+ replace_phi_edge_with_variable (cond_bb, e1, phi, arg);
/* Note that we optimized this PHI. */
return true;
return false;
}
-/* The function absolute_replacement does the main work of doing the absolute
+/* 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. */
+ 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
-abs_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
+minmax_replacement (basic_block cond_bb, basic_block middle_bb,
+ edge e0, edge e1, tree phi,
+ tree arg0, tree arg1)
{
- tree result;
- basic_block other_block = NULL;
- basic_block cond_block = NULL;
- tree new, cond;
- block_stmt_iterator bsi;
+ tree result, type;
+ tree cond, new;
edge true_edge, false_edge;
- tree assign = NULL;
- edge e;
- tree rhs = NULL, lhs = NULL;
- bool negate;
- enum tree_code cond_code;
+ enum tree_code cmp, minmax, ass_code;
+ tree smaller, larger, arg_true, arg_false;
+ block_stmt_iterator bsi, bsi_from;
- /* If the type says honor signed zeros we cannot do this
- optimization. */
- if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
+ type = TREE_TYPE (PHI_RESULT (phi));
+
+ /* The optimization may be unsafe due to NaNs. */
+ if (HONOR_NANS (TYPE_MODE (type)))
return false;
- if (!candidate_bb_for_phi_optimization (bb, &cond_block, &other_block))
+ 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;
- /* OTHER_BLOCK must have only one executable statement which must have the
- form arg0 = -arg1 or arg1 = -arg0. */
- bsi = bsi_start (other_block);
- while (!bsi_end_p (bsi))
+ /* 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
{
- tree stmt = bsi_stmt (bsi);
+ gcc_assert (false_edge == e0);
+ gcc_assert (true_edge == e1);
+ arg_true = arg1;
+ arg_false = arg0;
+ }
- /* Empty statements and labels are uninteresting. */
- if (TREE_CODE (stmt) == LABEL_EXPR
- || IS_EMPTY_STMT (stmt))
- {
- bsi_next (&bsi);
- continue;
- }
+ 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 we found the assignment, but it was not the only executable
- statement in OTHER_BLOCK, then we can not optimize. */
- if (assign)
+ 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) != MODIFY_EXPR)
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);
- }
+ lhs = TREE_OPERAND (assign, 0);
+ rhs = TREE_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
- return false;
+ {
+ /* 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 = build2 (MODIFY_EXPR, type, result,
+ build2 (minmax, type, arg0, arg1));
+ SSA_NAME_DEF_STMT (result) = new;
+ bsi = bsi_last (cond_bb);
+ bsi_insert_before (&bsi, new, 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. */
+
+static bool
+abs_replacement (basic_block cond_bb, basic_block middle_bb,
+ edge e0 ATTRIBUTE_UNUSED, edge e1,
+ tree phi, tree arg0, tree arg1)
+{
+ tree result;
+ tree new, cond;
+ block_stmt_iterator bsi;
+ edge true_edge, false_edge;
+ tree assign;
+ edge e;
+ tree rhs, lhs;
+ bool negate;
+ enum tree_code cond_code;
+
+ /* If the type says honor signed zeros we cannot do this
+ optimization. */
+ if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
+ return false;
+
+ /* OTHER_BLOCK must have only one executable statement which must have the
+ form arg0 = -arg1 or arg1 = -arg0. */
+
+ 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) != MODIFY_EXPR)
+ return false;
+
+ lhs = TREE_OPERAND (assign, 0);
+ rhs = TREE_OPERAND (assign, 1);
+
+ if (TREE_CODE (rhs) != NEGATE_EXPR)
+ return false;
- cond = COND_EXPR_COND (last_stmt (cond_block));
+ 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);
/* Only relationals comparing arg[01] against zero are interesting. */
&& cond_code != LT_EXPR && cond_code != LE_EXPR)
return false;
- /* Make sure the conditional is arg[01] OP y. */
+ /* Make sure the conditional is arg[01] OP y. */
if (TREE_OPERAND (cond, 0) != rhs)
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_block, &true_edge, &false_edge);
+ extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
/* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
e = true_edge;
else
e = false_edge;
-
- if (e->dest == other_block)
+
+ if (e->dest == middle_bb)
negate = true;
else
negate = 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_tmp_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));
+ /* Build the modify expression with abs expression. */
+ new = build2 (MODIFY_EXPR, TREE_TYPE (lhs),
+ lhs, build1 (ABS_EXPR, TREE_TYPE (lhs), rhs));
+ SSA_NAME_DEF_STMT (lhs) = new;
- replace_phi_with_stmt (bsi_start (bb), bb, cond_block, phi, new);
+ bsi = bsi_last (cond_bb);
+ bsi_insert_before (&bsi, new, BSI_NEW_STMT);
if (negate)
{
-
- /* Get the right BSI. We want to insert after the recently
+ /* 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. */
- bsi = bsi_start (bb);
- bsi_next (&bsi);
- new = build (MODIFY_EXPR, TREE_TYPE (result),
- result, build1 (NEGATE_EXPR, TREE_TYPE (lhs), lhs));
+ new = build2 (MODIFY_EXPR, TREE_TYPE (result),
+ result, build1 (NEGATE_EXPR, TREE_TYPE (lhs), lhs));
+ SSA_NAME_DEF_STMT (result) = new;
bsi_insert_after (&bsi, new, BSI_NEW_STMT);
-
- /* Register the new statement as defining the temporary -- this is
- normally done by replace_phi_with_stmt, but the link will be wrong
- if we had to negate the resulting value. */
- SSA_NAME_DEF_STMT (result) = new;
}
+ replace_phi_edge_with_variable (cond_bb, e1, phi, result);
+
/* Note that we optimized this PHI. */
return true;
}
/* Always do these optimizations if we have SSA
- trees to work on. */
+ trees to work on. */
static bool
gate_phiopt (void)
{
return 1;
}
-
+
struct tree_opt_pass pass_phiopt =
{
"phiopt", /* name */
NULL, /* next */
0, /* static_pass_number */
TV_TREE_PHIOPT, /* tv_id */
- PROP_cfg | PROP_ssa, /* properties_required */
+ 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_flags_finish */
- | TODO_verify_ssa | TODO_rename_vars
+ TODO_cleanup_cfg
+ | TODO_dump_func
+ | TODO_ggc_collect
+ | TODO_verify_ssa
| TODO_verify_flow
+ | TODO_verify_stmts, /* todo_flags_finish */
+ 0 /* letter */
};
-
-
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