/* SSA Jump Threading
|
/* SSA Jump Threading
|
Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
|
Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
|
Contributed by Jeff Law <law@redhat.com>
|
Contributed by Jeff Law <law@redhat.com>
|
|
|
This file is part of GCC.
|
This file is part of GCC.
|
|
|
GCC is free software; you can redistribute it and/or modify
|
GCC is free software; you can redistribute it and/or modify
|
it under the terms of the GNU General Public License as published by
|
it under the terms of the GNU General Public License as published by
|
the Free Software Foundation; either version 3, or (at your option)
|
the Free Software Foundation; either version 3, or (at your option)
|
any later version.
|
any later version.
|
|
|
GCC is distributed in the hope that it will be useful,
|
GCC is distributed in the hope that it will be useful,
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
GNU General Public License for more details.
|
GNU General Public License for more details.
|
|
|
You should have received a copy of the GNU General Public License
|
You should have received a copy of the GNU General Public License
|
along with GCC; see the file COPYING3. If not see
|
along with GCC; see the file COPYING3. If not see
|
<http://www.gnu.org/licenses/>. */
|
<http://www.gnu.org/licenses/>. */
|
|
|
#include "config.h"
|
#include "config.h"
|
#include "system.h"
|
#include "system.h"
|
#include "coretypes.h"
|
#include "coretypes.h"
|
#include "tm.h"
|
#include "tm.h"
|
#include "tree.h"
|
#include "tree.h"
|
#include "flags.h"
|
#include "flags.h"
|
#include "rtl.h"
|
#include "rtl.h"
|
#include "tm_p.h"
|
#include "tm_p.h"
|
#include "ggc.h"
|
#include "ggc.h"
|
#include "basic-block.h"
|
#include "basic-block.h"
|
#include "cfgloop.h"
|
#include "cfgloop.h"
|
#include "output.h"
|
#include "output.h"
|
#include "expr.h"
|
#include "expr.h"
|
#include "function.h"
|
#include "function.h"
|
#include "diagnostic.h"
|
#include "diagnostic.h"
|
#include "timevar.h"
|
#include "timevar.h"
|
#include "tree-dump.h"
|
#include "tree-dump.h"
|
#include "tree-flow.h"
|
#include "tree-flow.h"
|
#include "domwalk.h"
|
#include "domwalk.h"
|
#include "real.h"
|
#include "real.h"
|
#include "tree-pass.h"
|
#include "tree-pass.h"
|
#include "tree-ssa-propagate.h"
|
#include "tree-ssa-propagate.h"
|
#include "langhooks.h"
|
#include "langhooks.h"
|
#include "params.h"
|
#include "params.h"
|
|
|
/* To avoid code explosion due to jump threading, we limit the
|
/* To avoid code explosion due to jump threading, we limit the
|
number of statements we are going to copy. This variable
|
number of statements we are going to copy. This variable
|
holds the number of statements currently seen that we'll have
|
holds the number of statements currently seen that we'll have
|
to copy as part of the jump threading process. */
|
to copy as part of the jump threading process. */
|
static int stmt_count;
|
static int stmt_count;
|
|
|
/* Return TRUE if we may be able to thread an incoming edge into
|
/* Return TRUE if we may be able to thread an incoming edge into
|
BB to an outgoing edge from BB. Return FALSE otherwise. */
|
BB to an outgoing edge from BB. Return FALSE otherwise. */
|
|
|
bool
|
bool
|
potentially_threadable_block (basic_block bb)
|
potentially_threadable_block (basic_block bb)
|
{
|
{
|
block_stmt_iterator bsi;
|
block_stmt_iterator bsi;
|
|
|
/* If BB has a single successor or a single predecessor, then
|
/* If BB has a single successor or a single predecessor, then
|
there is no threading opportunity. */
|
there is no threading opportunity. */
|
if (single_succ_p (bb) || single_pred_p (bb))
|
if (single_succ_p (bb) || single_pred_p (bb))
|
return false;
|
return false;
|
|
|
/* If BB does not end with a conditional, switch or computed goto,
|
/* If BB does not end with a conditional, switch or computed goto,
|
then there is no threading opportunity. */
|
then there is no threading opportunity. */
|
bsi = bsi_last (bb);
|
bsi = bsi_last (bb);
|
if (bsi_end_p (bsi)
|
if (bsi_end_p (bsi)
|
|| ! bsi_stmt (bsi)
|
|| ! bsi_stmt (bsi)
|
|| (TREE_CODE (bsi_stmt (bsi)) != COND_EXPR
|
|| (TREE_CODE (bsi_stmt (bsi)) != COND_EXPR
|
&& TREE_CODE (bsi_stmt (bsi)) != GOTO_EXPR
|
&& TREE_CODE (bsi_stmt (bsi)) != GOTO_EXPR
|
&& TREE_CODE (bsi_stmt (bsi)) != SWITCH_EXPR))
|
&& TREE_CODE (bsi_stmt (bsi)) != SWITCH_EXPR))
|
return false;
|
return false;
|
|
|
return true;
|
return true;
|
}
|
}
|
|
|
/* Return the LHS of any ASSERT_EXPR where OP appears as the first
|
/* Return the LHS of any ASSERT_EXPR where OP appears as the first
|
argument to the ASSERT_EXPR and in which the ASSERT_EXPR dominates
|
argument to the ASSERT_EXPR and in which the ASSERT_EXPR dominates
|
BB. If no such ASSERT_EXPR is found, return OP. */
|
BB. If no such ASSERT_EXPR is found, return OP. */
|
|
|
static tree
|
static tree
|
lhs_of_dominating_assert (tree op, basic_block bb, tree stmt)
|
lhs_of_dominating_assert (tree op, basic_block bb, tree stmt)
|
{
|
{
|
imm_use_iterator imm_iter;
|
imm_use_iterator imm_iter;
|
tree use_stmt;
|
tree use_stmt;
|
use_operand_p use_p;
|
use_operand_p use_p;
|
|
|
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, op)
|
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, op)
|
{
|
{
|
use_stmt = USE_STMT (use_p);
|
use_stmt = USE_STMT (use_p);
|
if (use_stmt != stmt
|
if (use_stmt != stmt
|
&& TREE_CODE (use_stmt) == MODIFY_EXPR
|
&& TREE_CODE (use_stmt) == MODIFY_EXPR
|
&& TREE_CODE (TREE_OPERAND (use_stmt, 1)) == ASSERT_EXPR
|
&& TREE_CODE (TREE_OPERAND (use_stmt, 1)) == ASSERT_EXPR
|
&& TREE_OPERAND (TREE_OPERAND (use_stmt, 1), 0) == op
|
&& TREE_OPERAND (TREE_OPERAND (use_stmt, 1), 0) == op
|
&& dominated_by_p (CDI_DOMINATORS, bb, bb_for_stmt (use_stmt)))
|
&& dominated_by_p (CDI_DOMINATORS, bb, bb_for_stmt (use_stmt)))
|
{
|
{
|
return TREE_OPERAND (use_stmt, 0);
|
return TREE_OPERAND (use_stmt, 0);
|
}
|
}
|
}
|
}
|
return op;
|
return op;
|
}
|
}
|
|
|
|
|
/* We record temporary equivalences created by PHI nodes or
|
/* We record temporary equivalences created by PHI nodes or
|
statements within the target block. Doing so allows us to
|
statements within the target block. Doing so allows us to
|
identify more jump threading opportunities, even in blocks
|
identify more jump threading opportunities, even in blocks
|
with side effects.
|
with side effects.
|
|
|
We keep track of those temporary equivalences in a stack
|
We keep track of those temporary equivalences in a stack
|
structure so that we can unwind them when we're done processing
|
structure so that we can unwind them when we're done processing
|
a particular edge. This routine handles unwinding the data
|
a particular edge. This routine handles unwinding the data
|
structures. */
|
structures. */
|
|
|
static void
|
static void
|
remove_temporary_equivalences (VEC(tree, heap) **stack)
|
remove_temporary_equivalences (VEC(tree, heap) **stack)
|
{
|
{
|
while (VEC_length (tree, *stack) > 0)
|
while (VEC_length (tree, *stack) > 0)
|
{
|
{
|
tree prev_value, dest;
|
tree prev_value, dest;
|
|
|
dest = VEC_pop (tree, *stack);
|
dest = VEC_pop (tree, *stack);
|
|
|
/* A NULL value indicates we should stop unwinding, otherwise
|
/* A NULL value indicates we should stop unwinding, otherwise
|
pop off the next entry as they're recorded in pairs. */
|
pop off the next entry as they're recorded in pairs. */
|
if (dest == NULL)
|
if (dest == NULL)
|
break;
|
break;
|
|
|
prev_value = VEC_pop (tree, *stack);
|
prev_value = VEC_pop (tree, *stack);
|
SSA_NAME_VALUE (dest) = prev_value;
|
SSA_NAME_VALUE (dest) = prev_value;
|
}
|
}
|
}
|
}
|
|
|
/* Record a temporary equivalence, saving enough information so that
|
/* Record a temporary equivalence, saving enough information so that
|
we can restore the state of recorded equivalences when we're
|
we can restore the state of recorded equivalences when we're
|
done processing the current edge. */
|
done processing the current edge. */
|
|
|
static void
|
static void
|
record_temporary_equivalence (tree x, tree y, VEC(tree, heap) **stack)
|
record_temporary_equivalence (tree x, tree y, VEC(tree, heap) **stack)
|
{
|
{
|
tree prev_x = SSA_NAME_VALUE (x);
|
tree prev_x = SSA_NAME_VALUE (x);
|
|
|
if (TREE_CODE (y) == SSA_NAME)
|
if (TREE_CODE (y) == SSA_NAME)
|
{
|
{
|
tree tmp = SSA_NAME_VALUE (y);
|
tree tmp = SSA_NAME_VALUE (y);
|
y = tmp ? tmp : y;
|
y = tmp ? tmp : y;
|
}
|
}
|
|
|
SSA_NAME_VALUE (x) = y;
|
SSA_NAME_VALUE (x) = y;
|
VEC_reserve (tree, heap, *stack, 2);
|
VEC_reserve (tree, heap, *stack, 2);
|
VEC_quick_push (tree, *stack, prev_x);
|
VEC_quick_push (tree, *stack, prev_x);
|
VEC_quick_push (tree, *stack, x);
|
VEC_quick_push (tree, *stack, x);
|
}
|
}
|
|
|
/* Record temporary equivalences created by PHIs at the target of the
|
/* Record temporary equivalences created by PHIs at the target of the
|
edge E. Record unwind information for the equivalences onto STACK.
|
edge E. Record unwind information for the equivalences onto STACK.
|
|
|
If a PHI which prevents threading is encountered, then return FALSE
|
If a PHI which prevents threading is encountered, then return FALSE
|
indicating we should not thread this edge, else return TRUE. */
|
indicating we should not thread this edge, else return TRUE. */
|
|
|
static bool
|
static bool
|
record_temporary_equivalences_from_phis (edge e, VEC(tree, heap) **stack)
|
record_temporary_equivalences_from_phis (edge e, VEC(tree, heap) **stack)
|
{
|
{
|
tree phi;
|
tree phi;
|
|
|
/* Each PHI creates a temporary equivalence, record them.
|
/* Each PHI creates a temporary equivalence, record them.
|
These are context sensitive equivalences and will be removed
|
These are context sensitive equivalences and will be removed
|
later. */
|
later. */
|
for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
|
for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
|
{
|
{
|
tree src = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
tree src = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
tree dst = PHI_RESULT (phi);
|
tree dst = PHI_RESULT (phi);
|
|
|
/* If the desired argument is not the same as this PHI's result
|
/* If the desired argument is not the same as this PHI's result
|
and it is set by a PHI in E->dest, then we can not thread
|
and it is set by a PHI in E->dest, then we can not thread
|
through E->dest. */
|
through E->dest. */
|
if (src != dst
|
if (src != dst
|
&& TREE_CODE (src) == SSA_NAME
|
&& TREE_CODE (src) == SSA_NAME
|
&& TREE_CODE (SSA_NAME_DEF_STMT (src)) == PHI_NODE
|
&& TREE_CODE (SSA_NAME_DEF_STMT (src)) == PHI_NODE
|
&& bb_for_stmt (SSA_NAME_DEF_STMT (src)) == e->dest)
|
&& bb_for_stmt (SSA_NAME_DEF_STMT (src)) == e->dest)
|
return false;
|
return false;
|
|
|
/* We consider any non-virtual PHI as a statement since it
|
/* We consider any non-virtual PHI as a statement since it
|
count result in a constant assignment or copy operation. */
|
count result in a constant assignment or copy operation. */
|
if (is_gimple_reg (dst))
|
if (is_gimple_reg (dst))
|
stmt_count++;
|
stmt_count++;
|
|
|
record_temporary_equivalence (dst, src, stack);
|
record_temporary_equivalence (dst, src, stack);
|
}
|
}
|
return true;
|
return true;
|
}
|
}
|
|
|
/* Try to simplify each statement in E->dest, ultimately leading to
|
/* Try to simplify each statement in E->dest, ultimately leading to
|
a simplification of the COND_EXPR at the end of E->dest.
|
a simplification of the COND_EXPR at the end of E->dest.
|
|
|
Record unwind information for temporary equivalences onto STACK.
|
Record unwind information for temporary equivalences onto STACK.
|
|
|
Use SIMPLIFY (a pointer to a callback function) to further simplify
|
Use SIMPLIFY (a pointer to a callback function) to further simplify
|
statements using pass specific information.
|
statements using pass specific information.
|
|
|
We might consider marking just those statements which ultimately
|
We might consider marking just those statements which ultimately
|
feed the COND_EXPR. It's not clear if the overhead of bookkeeping
|
feed the COND_EXPR. It's not clear if the overhead of bookkeeping
|
would be recovered by trying to simplify fewer statements.
|
would be recovered by trying to simplify fewer statements.
|
|
|
If we are able to simplify a statement into the form
|
If we are able to simplify a statement into the form
|
SSA_NAME = (SSA_NAME | gimple invariant), then we can record
|
SSA_NAME = (SSA_NAME | gimple invariant), then we can record
|
a context sensitive equivalency which may help us simplify
|
a context sensitive equivalency which may help us simplify
|
later statements in E->dest. */
|
later statements in E->dest. */
|
|
|
static tree
|
static tree
|
record_temporary_equivalences_from_stmts_at_dest (edge e,
|
record_temporary_equivalences_from_stmts_at_dest (edge e,
|
VEC(tree, heap) **stack,
|
VEC(tree, heap) **stack,
|
tree (*simplify) (tree,
|
tree (*simplify) (tree,
|
tree))
|
tree))
|
{
|
{
|
block_stmt_iterator bsi;
|
block_stmt_iterator bsi;
|
tree stmt = NULL;
|
tree stmt = NULL;
|
int max_stmt_count;
|
int max_stmt_count;
|
|
|
max_stmt_count = PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS);
|
max_stmt_count = PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS);
|
|
|
/* Walk through each statement in the block recording equivalences
|
/* Walk through each statement in the block recording equivalences
|
we discover. Note any equivalences we discover are context
|
we discover. Note any equivalences we discover are context
|
sensitive (ie, are dependent on traversing E) and must be unwound
|
sensitive (ie, are dependent on traversing E) and must be unwound
|
when we're finished processing E. */
|
when we're finished processing E. */
|
for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi))
|
for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi))
|
{
|
{
|
tree cached_lhs = NULL;
|
tree cached_lhs = NULL;
|
|
|
stmt = bsi_stmt (bsi);
|
stmt = bsi_stmt (bsi);
|
|
|
/* Ignore empty statements and labels. */
|
/* Ignore empty statements and labels. */
|
if (IS_EMPTY_STMT (stmt) || TREE_CODE (stmt) == LABEL_EXPR)
|
if (IS_EMPTY_STMT (stmt) || TREE_CODE (stmt) == LABEL_EXPR)
|
continue;
|
continue;
|
|
|
/* If the statement has volatile operands, then we assume we
|
/* If the statement has volatile operands, then we assume we
|
can not thread through this block. This is overly
|
can not thread through this block. This is overly
|
conservative in some ways. */
|
conservative in some ways. */
|
if (TREE_CODE (stmt) == ASM_EXPR && ASM_VOLATILE_P (stmt))
|
if (TREE_CODE (stmt) == ASM_EXPR && ASM_VOLATILE_P (stmt))
|
return NULL;
|
return NULL;
|
|
|
/* If duplicating this block is going to cause too much code
|
/* If duplicating this block is going to cause too much code
|
expansion, then do not thread through this block. */
|
expansion, then do not thread through this block. */
|
stmt_count++;
|
stmt_count++;
|
if (stmt_count > max_stmt_count)
|
if (stmt_count > max_stmt_count)
|
return NULL;
|
return NULL;
|
|
|
/* If this is not a MODIFY_EXPR which sets an SSA_NAME to a new
|
/* If this is not a MODIFY_EXPR which sets an SSA_NAME to a new
|
value, then do not try to simplify this statement as it will
|
value, then do not try to simplify this statement as it will
|
not simplify in any way that is helpful for jump threading. */
|
not simplify in any way that is helpful for jump threading. */
|
if (TREE_CODE (stmt) != MODIFY_EXPR
|
if (TREE_CODE (stmt) != MODIFY_EXPR
|
|| TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME)
|
|| TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME)
|
continue;
|
continue;
|
|
|
/* At this point we have a statement which assigns an RHS to an
|
/* At this point we have a statement which assigns an RHS to an
|
SSA_VAR on the LHS. We want to try and simplify this statement
|
SSA_VAR on the LHS. We want to try and simplify this statement
|
to expose more context sensitive equivalences which in turn may
|
to expose more context sensitive equivalences which in turn may
|
allow us to simplify the condition at the end of the loop.
|
allow us to simplify the condition at the end of the loop.
|
|
|
Handle simple copy operations as well as implied copies from
|
Handle simple copy operations as well as implied copies from
|
ASSERT_EXPRs. */
|
ASSERT_EXPRs. */
|
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME)
|
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME)
|
cached_lhs = TREE_OPERAND (stmt, 1);
|
cached_lhs = TREE_OPERAND (stmt, 1);
|
else if (TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
|
else if (TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
|
cached_lhs = TREE_OPERAND (TREE_OPERAND (stmt, 1), 0);
|
cached_lhs = TREE_OPERAND (TREE_OPERAND (stmt, 1), 0);
|
else
|
else
|
{
|
{
|
/* A statement that is not a trivial copy or ASSERT_EXPR.
|
/* A statement that is not a trivial copy or ASSERT_EXPR.
|
We're going to temporarily copy propagate the operands
|
We're going to temporarily copy propagate the operands
|
and see if that allows us to simplify this statement. */
|
and see if that allows us to simplify this statement. */
|
tree *copy, pre_fold_expr;
|
tree *copy, pre_fold_expr;
|
ssa_op_iter iter;
|
ssa_op_iter iter;
|
use_operand_p use_p;
|
use_operand_p use_p;
|
unsigned int num, i = 0;
|
unsigned int num, i = 0;
|
|
|
num = NUM_SSA_OPERANDS (stmt, (SSA_OP_USE | SSA_OP_VUSE));
|
num = NUM_SSA_OPERANDS (stmt, (SSA_OP_USE | SSA_OP_VUSE));
|
copy = XCNEWVEC (tree, num);
|
copy = XCNEWVEC (tree, num);
|
|
|
/* Make a copy of the uses & vuses into USES_COPY, then cprop into
|
/* Make a copy of the uses & vuses into USES_COPY, then cprop into
|
the operands. */
|
the operands. */
|
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
|
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
|
{
|
{
|
tree tmp = NULL;
|
tree tmp = NULL;
|
tree use = USE_FROM_PTR (use_p);
|
tree use = USE_FROM_PTR (use_p);
|
|
|
copy[i++] = use;
|
copy[i++] = use;
|
if (TREE_CODE (use) == SSA_NAME)
|
if (TREE_CODE (use) == SSA_NAME)
|
tmp = SSA_NAME_VALUE (use);
|
tmp = SSA_NAME_VALUE (use);
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
SET_USE (use_p, tmp);
|
SET_USE (use_p, tmp);
|
}
|
}
|
|
|
/* Try to fold/lookup the new expression. Inserting the
|
/* Try to fold/lookup the new expression. Inserting the
|
expression into the hash table is unlikely to help
|
expression into the hash table is unlikely to help
|
Sadly, we have to handle conditional assignments specially
|
Sadly, we have to handle conditional assignments specially
|
here, because fold expects all the operands of an expression
|
here, because fold expects all the operands of an expression
|
to be folded before the expression itself is folded, but we
|
to be folded before the expression itself is folded, but we
|
can't just substitute the folded condition here. */
|
can't just substitute the folded condition here. */
|
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == COND_EXPR)
|
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == COND_EXPR)
|
{
|
{
|
tree cond = COND_EXPR_COND (TREE_OPERAND (stmt, 1));
|
tree cond = COND_EXPR_COND (TREE_OPERAND (stmt, 1));
|
cond = fold (cond);
|
cond = fold (cond);
|
if (cond == boolean_true_node)
|
if (cond == boolean_true_node)
|
pre_fold_expr = COND_EXPR_THEN (TREE_OPERAND (stmt, 1));
|
pre_fold_expr = COND_EXPR_THEN (TREE_OPERAND (stmt, 1));
|
else if (cond == boolean_false_node)
|
else if (cond == boolean_false_node)
|
pre_fold_expr = COND_EXPR_ELSE (TREE_OPERAND (stmt, 1));
|
pre_fold_expr = COND_EXPR_ELSE (TREE_OPERAND (stmt, 1));
|
else
|
else
|
pre_fold_expr = TREE_OPERAND (stmt, 1);
|
pre_fold_expr = TREE_OPERAND (stmt, 1);
|
}
|
}
|
else
|
else
|
pre_fold_expr = TREE_OPERAND (stmt, 1);
|
pre_fold_expr = TREE_OPERAND (stmt, 1);
|
|
|
if (pre_fold_expr)
|
if (pre_fold_expr)
|
{
|
{
|
cached_lhs = fold (pre_fold_expr);
|
cached_lhs = fold (pre_fold_expr);
|
if (TREE_CODE (cached_lhs) != SSA_NAME
|
if (TREE_CODE (cached_lhs) != SSA_NAME
|
&& !is_gimple_min_invariant (cached_lhs))
|
&& !is_gimple_min_invariant (cached_lhs))
|
cached_lhs = (*simplify) (stmt, stmt);
|
cached_lhs = (*simplify) (stmt, stmt);
|
}
|
}
|
|
|
/* Restore the statement's original uses/defs. */
|
/* Restore the statement's original uses/defs. */
|
i = 0;
|
i = 0;
|
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
|
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
|
SET_USE (use_p, copy[i++]);
|
SET_USE (use_p, copy[i++]);
|
|
|
free (copy);
|
free (copy);
|
}
|
}
|
|
|
/* Record the context sensitive equivalence if we were able
|
/* Record the context sensitive equivalence if we were able
|
to simplify this statement. */
|
to simplify this statement. */
|
if (cached_lhs
|
if (cached_lhs
|
&& (TREE_CODE (cached_lhs) == SSA_NAME
|
&& (TREE_CODE (cached_lhs) == SSA_NAME
|
|| is_gimple_min_invariant (cached_lhs)))
|
|| is_gimple_min_invariant (cached_lhs)))
|
record_temporary_equivalence (TREE_OPERAND (stmt, 0),
|
record_temporary_equivalence (TREE_OPERAND (stmt, 0),
|
cached_lhs,
|
cached_lhs,
|
stack);
|
stack);
|
}
|
}
|
return stmt;
|
return stmt;
|
}
|
}
|
|
|
/* Simplify the control statement at the end of the block E->dest.
|
/* Simplify the control statement at the end of the block E->dest.
|
|
|
To avoid allocating memory unnecessarily, a scratch COND_EXPR
|
To avoid allocating memory unnecessarily, a scratch COND_EXPR
|
is available to use/clobber in DUMMY_COND.
|
is available to use/clobber in DUMMY_COND.
|
|
|
Use SIMPLIFY (a pointer to a callback function) to further simplify
|
Use SIMPLIFY (a pointer to a callback function) to further simplify
|
a condition using pass specific information.
|
a condition using pass specific information.
|
|
|
Return the simplified condition or NULL if simplification could
|
Return the simplified condition or NULL if simplification could
|
not be performed. */
|
not be performed. */
|
|
|
static tree
|
static tree
|
simplify_control_stmt_condition (edge e,
|
simplify_control_stmt_condition (edge e,
|
tree stmt,
|
tree stmt,
|
tree dummy_cond,
|
tree dummy_cond,
|
tree (*simplify) (tree, tree),
|
tree (*simplify) (tree, tree),
|
bool handle_dominating_asserts)
|
bool handle_dominating_asserts)
|
{
|
{
|
tree cond, cached_lhs;
|
tree cond, cached_lhs;
|
|
|
if (TREE_CODE (stmt) == COND_EXPR)
|
if (TREE_CODE (stmt) == COND_EXPR)
|
cond = COND_EXPR_COND (stmt);
|
cond = COND_EXPR_COND (stmt);
|
else if (TREE_CODE (stmt) == GOTO_EXPR)
|
else if (TREE_CODE (stmt) == GOTO_EXPR)
|
cond = GOTO_DESTINATION (stmt);
|
cond = GOTO_DESTINATION (stmt);
|
else
|
else
|
cond = SWITCH_COND (stmt);
|
cond = SWITCH_COND (stmt);
|
|
|
/* For comparisons, we have to update both operands, then try
|
/* For comparisons, we have to update both operands, then try
|
to simplify the comparison. */
|
to simplify the comparison. */
|
if (COMPARISON_CLASS_P (cond))
|
if (COMPARISON_CLASS_P (cond))
|
{
|
{
|
tree op0, op1;
|
tree op0, op1;
|
enum tree_code cond_code;
|
enum tree_code cond_code;
|
|
|
op0 = TREE_OPERAND (cond, 0);
|
op0 = TREE_OPERAND (cond, 0);
|
op1 = TREE_OPERAND (cond, 1);
|
op1 = TREE_OPERAND (cond, 1);
|
cond_code = TREE_CODE (cond);
|
cond_code = TREE_CODE (cond);
|
|
|
/* Get the current value of both operands. */
|
/* Get the current value of both operands. */
|
if (TREE_CODE (op0) == SSA_NAME)
|
if (TREE_CODE (op0) == SSA_NAME)
|
{
|
{
|
tree tmp = SSA_NAME_VALUE (op0);
|
tree tmp = SSA_NAME_VALUE (op0);
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
op0 = tmp;
|
op0 = tmp;
|
}
|
}
|
|
|
if (TREE_CODE (op1) == SSA_NAME)
|
if (TREE_CODE (op1) == SSA_NAME)
|
{
|
{
|
tree tmp = SSA_NAME_VALUE (op1);
|
tree tmp = SSA_NAME_VALUE (op1);
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
op1 = tmp;
|
op1 = tmp;
|
}
|
}
|
|
|
if (handle_dominating_asserts)
|
if (handle_dominating_asserts)
|
{
|
{
|
/* Now see if the operand was consumed by an ASSERT_EXPR
|
/* Now see if the operand was consumed by an ASSERT_EXPR
|
which dominates E->src. If so, we want to replace the
|
which dominates E->src. If so, we want to replace the
|
operand with the LHS of the ASSERT_EXPR. */
|
operand with the LHS of the ASSERT_EXPR. */
|
if (TREE_CODE (op0) == SSA_NAME)
|
if (TREE_CODE (op0) == SSA_NAME)
|
op0 = lhs_of_dominating_assert (op0, e->src, stmt);
|
op0 = lhs_of_dominating_assert (op0, e->src, stmt);
|
|
|
if (TREE_CODE (op1) == SSA_NAME)
|
if (TREE_CODE (op1) == SSA_NAME)
|
op1 = lhs_of_dominating_assert (op1, e->src, stmt);
|
op1 = lhs_of_dominating_assert (op1, e->src, stmt);
|
}
|
}
|
|
|
/* We may need to canonicalize the comparison. For
|
/* We may need to canonicalize the comparison. For
|
example, op0 might be a constant while op1 is an
|
example, op0 might be a constant while op1 is an
|
SSA_NAME. Failure to canonicalize will cause us to
|
SSA_NAME. Failure to canonicalize will cause us to
|
miss threading opportunities. */
|
miss threading opportunities. */
|
if (cond_code != SSA_NAME
|
if (cond_code != SSA_NAME
|
&& tree_swap_operands_p (op0, op1, false))
|
&& tree_swap_operands_p (op0, op1, false))
|
{
|
{
|
tree tmp;
|
tree tmp;
|
cond_code = swap_tree_comparison (TREE_CODE (cond));
|
cond_code = swap_tree_comparison (TREE_CODE (cond));
|
tmp = op0;
|
tmp = op0;
|
op0 = op1;
|
op0 = op1;
|
op1 = tmp;
|
op1 = tmp;
|
}
|
}
|
|
|
/* Stuff the operator and operands into our dummy conditional
|
/* Stuff the operator and operands into our dummy conditional
|
expression. */
|
expression. */
|
TREE_SET_CODE (COND_EXPR_COND (dummy_cond), cond_code);
|
TREE_SET_CODE (COND_EXPR_COND (dummy_cond), cond_code);
|
TREE_OPERAND (COND_EXPR_COND (dummy_cond), 0) = op0;
|
TREE_OPERAND (COND_EXPR_COND (dummy_cond), 0) = op0;
|
TREE_OPERAND (COND_EXPR_COND (dummy_cond), 1) = op1;
|
TREE_OPERAND (COND_EXPR_COND (dummy_cond), 1) = op1;
|
|
|
/* We absolutely do not care about any type conversions
|
/* We absolutely do not care about any type conversions
|
we only care about a zero/nonzero value. */
|
we only care about a zero/nonzero value. */
|
fold_defer_overflow_warnings ();
|
fold_defer_overflow_warnings ();
|
|
|
cached_lhs = fold (COND_EXPR_COND (dummy_cond));
|
cached_lhs = fold (COND_EXPR_COND (dummy_cond));
|
while (TREE_CODE (cached_lhs) == NOP_EXPR
|
while (TREE_CODE (cached_lhs) == NOP_EXPR
|
|| TREE_CODE (cached_lhs) == CONVERT_EXPR
|
|| TREE_CODE (cached_lhs) == CONVERT_EXPR
|
|| TREE_CODE (cached_lhs) == NON_LVALUE_EXPR)
|
|| TREE_CODE (cached_lhs) == NON_LVALUE_EXPR)
|
cached_lhs = TREE_OPERAND (cached_lhs, 0);
|
cached_lhs = TREE_OPERAND (cached_lhs, 0);
|
|
|
fold_undefer_overflow_warnings (is_gimple_min_invariant (cached_lhs),
|
fold_undefer_overflow_warnings (is_gimple_min_invariant (cached_lhs),
|
stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
|
stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
|
|
|
/* If we have not simplified the condition down to an invariant,
|
/* If we have not simplified the condition down to an invariant,
|
then use the pass specific callback to simplify the condition. */
|
then use the pass specific callback to simplify the condition. */
|
if (! is_gimple_min_invariant (cached_lhs))
|
if (! is_gimple_min_invariant (cached_lhs))
|
cached_lhs = (*simplify) (dummy_cond, stmt);
|
cached_lhs = (*simplify) (dummy_cond, stmt);
|
}
|
}
|
|
|
/* We can have conditionals which just test the state of a variable
|
/* We can have conditionals which just test the state of a variable
|
rather than use a relational operator. These are simpler to handle. */
|
rather than use a relational operator. These are simpler to handle. */
|
else if (TREE_CODE (cond) == SSA_NAME)
|
else if (TREE_CODE (cond) == SSA_NAME)
|
{
|
{
|
cached_lhs = cond;
|
cached_lhs = cond;
|
|
|
/* Get the variable's current value from the equivalency chains.
|
/* Get the variable's current value from the equivalency chains.
|
|
|
It is possible to get loops in the SSA_NAME_VALUE chains
|
It is possible to get loops in the SSA_NAME_VALUE chains
|
(consider threading the backedge of a loop where we have
|
(consider threading the backedge of a loop where we have
|
a loop invariant SSA_NAME used in the condition. */
|
a loop invariant SSA_NAME used in the condition. */
|
if (cached_lhs
|
if (cached_lhs
|
&& TREE_CODE (cached_lhs) == SSA_NAME
|
&& TREE_CODE (cached_lhs) == SSA_NAME
|
&& SSA_NAME_VALUE (cached_lhs))
|
&& SSA_NAME_VALUE (cached_lhs))
|
cached_lhs = SSA_NAME_VALUE (cached_lhs);
|
cached_lhs = SSA_NAME_VALUE (cached_lhs);
|
|
|
/* If we're dominated by a suitable ASSERT_EXPR, then
|
/* If we're dominated by a suitable ASSERT_EXPR, then
|
update CACHED_LHS appropriately. */
|
update CACHED_LHS appropriately. */
|
if (handle_dominating_asserts && TREE_CODE (cached_lhs) == SSA_NAME)
|
if (handle_dominating_asserts && TREE_CODE (cached_lhs) == SSA_NAME)
|
cached_lhs = lhs_of_dominating_assert (cached_lhs, e->src, stmt);
|
cached_lhs = lhs_of_dominating_assert (cached_lhs, e->src, stmt);
|
|
|
/* If we haven't simplified to an invariant yet, then use the
|
/* If we haven't simplified to an invariant yet, then use the
|
pass specific callback to try and simplify it further. */
|
pass specific callback to try and simplify it further. */
|
if (cached_lhs && ! is_gimple_min_invariant (cached_lhs))
|
if (cached_lhs && ! is_gimple_min_invariant (cached_lhs))
|
cached_lhs = (*simplify) (stmt, stmt);
|
cached_lhs = (*simplify) (stmt, stmt);
|
}
|
}
|
else
|
else
|
cached_lhs = NULL;
|
cached_lhs = NULL;
|
|
|
return cached_lhs;
|
return cached_lhs;
|
}
|
}
|
|
|
/* We are exiting E->src, see if E->dest ends with a conditional
|
/* We are exiting E->src, see if E->dest ends with a conditional
|
jump which has a known value when reached via E.
|
jump which has a known value when reached via E.
|
|
|
Special care is necessary if E is a back edge in the CFG as we
|
Special care is necessary if E is a back edge in the CFG as we
|
may have already recorded equivalences for E->dest into our
|
may have already recorded equivalences for E->dest into our
|
various tables, including the result of the conditional at
|
various tables, including the result of the conditional at
|
the end of E->dest. Threading opportunities are severely
|
the end of E->dest. Threading opportunities are severely
|
limited in that case to avoid short-circuiting the loop
|
limited in that case to avoid short-circuiting the loop
|
incorrectly.
|
incorrectly.
|
|
|
Note it is quite common for the first block inside a loop to
|
Note it is quite common for the first block inside a loop to
|
end with a conditional which is either always true or always
|
end with a conditional which is either always true or always
|
false when reached via the loop backedge. Thus we do not want
|
false when reached via the loop backedge. Thus we do not want
|
to blindly disable threading across a loop backedge. */
|
to blindly disable threading across a loop backedge. */
|
|
|
void
|
void
|
thread_across_edge (tree dummy_cond,
|
thread_across_edge (tree dummy_cond,
|
edge e,
|
edge e,
|
bool handle_dominating_asserts,
|
bool handle_dominating_asserts,
|
VEC(tree, heap) **stack,
|
VEC(tree, heap) **stack,
|
tree (*simplify) (tree, tree))
|
tree (*simplify) (tree, tree))
|
{
|
{
|
tree stmt;
|
tree stmt;
|
|
|
/* If E is a backedge, then we want to verify that the COND_EXPR,
|
/* If E is a backedge, then we want to verify that the COND_EXPR,
|
SWITCH_EXPR or GOTO_EXPR at the end of e->dest is not affected
|
SWITCH_EXPR or GOTO_EXPR at the end of e->dest is not affected
|
by any statements in e->dest. If it is affected, then it is not
|
by any statements in e->dest. If it is affected, then it is not
|
safe to thread this edge. */
|
safe to thread this edge. */
|
if (e->flags & EDGE_DFS_BACK)
|
if (e->flags & EDGE_DFS_BACK)
|
{
|
{
|
ssa_op_iter iter;
|
ssa_op_iter iter;
|
use_operand_p use_p;
|
use_operand_p use_p;
|
tree last = bsi_stmt (bsi_last (e->dest));
|
tree last = bsi_stmt (bsi_last (e->dest));
|
|
|
FOR_EACH_SSA_USE_OPERAND (use_p, last, iter, SSA_OP_USE | SSA_OP_VUSE)
|
FOR_EACH_SSA_USE_OPERAND (use_p, last, iter, SSA_OP_USE | SSA_OP_VUSE)
|
{
|
{
|
tree use = USE_FROM_PTR (use_p);
|
tree use = USE_FROM_PTR (use_p);
|
|
|
if (TREE_CODE (use) == SSA_NAME
|
if (TREE_CODE (use) == SSA_NAME
|
&& TREE_CODE (SSA_NAME_DEF_STMT (use)) != PHI_NODE
|
&& TREE_CODE (SSA_NAME_DEF_STMT (use)) != PHI_NODE
|
&& bb_for_stmt (SSA_NAME_DEF_STMT (use)) == e->dest)
|
&& bb_for_stmt (SSA_NAME_DEF_STMT (use)) == e->dest)
|
goto fail;
|
goto fail;
|
}
|
}
|
}
|
}
|
|
|
stmt_count = 0;
|
stmt_count = 0;
|
|
|
/* PHIs create temporary equivalences. */
|
/* PHIs create temporary equivalences. */
|
if (!record_temporary_equivalences_from_phis (e, stack))
|
if (!record_temporary_equivalences_from_phis (e, stack))
|
goto fail;
|
goto fail;
|
|
|
/* Now walk each statement recording any context sensitive
|
/* Now walk each statement recording any context sensitive
|
temporary equivalences we can detect. */
|
temporary equivalences we can detect. */
|
stmt = record_temporary_equivalences_from_stmts_at_dest (e, stack, simplify);
|
stmt = record_temporary_equivalences_from_stmts_at_dest (e, stack, simplify);
|
if (!stmt)
|
if (!stmt)
|
goto fail;
|
goto fail;
|
|
|
/* If we stopped at a COND_EXPR or SWITCH_EXPR, see if we know which arm
|
/* If we stopped at a COND_EXPR or SWITCH_EXPR, see if we know which arm
|
will be taken. */
|
will be taken. */
|
if (TREE_CODE (stmt) == COND_EXPR
|
if (TREE_CODE (stmt) == COND_EXPR
|
|| TREE_CODE (stmt) == GOTO_EXPR
|
|| TREE_CODE (stmt) == GOTO_EXPR
|
|| TREE_CODE (stmt) == SWITCH_EXPR)
|
|| TREE_CODE (stmt) == SWITCH_EXPR)
|
{
|
{
|
tree cond;
|
tree cond;
|
|
|
/* Extract and simplify the condition. */
|
/* Extract and simplify the condition. */
|
cond = simplify_control_stmt_condition (e, stmt, dummy_cond, simplify, handle_dominating_asserts);
|
cond = simplify_control_stmt_condition (e, stmt, dummy_cond, simplify, handle_dominating_asserts);
|
|
|
if (cond && is_gimple_min_invariant (cond))
|
if (cond && is_gimple_min_invariant (cond))
|
{
|
{
|
edge taken_edge = find_taken_edge (e->dest, cond);
|
edge taken_edge = find_taken_edge (e->dest, cond);
|
basic_block dest = (taken_edge ? taken_edge->dest : NULL);
|
basic_block dest = (taken_edge ? taken_edge->dest : NULL);
|
|
|
if (dest == e->dest)
|
if (dest == e->dest)
|
goto fail;
|
goto fail;
|
|
|
remove_temporary_equivalences (stack);
|
remove_temporary_equivalences (stack);
|
register_jump_thread (e, taken_edge);
|
register_jump_thread (e, taken_edge);
|
}
|
}
|
}
|
}
|
|
|
fail:
|
fail:
|
remove_temporary_equivalences (stack);
|
remove_temporary_equivalences (stack);
|
}
|
}
|
|
|
