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re PR tree-optimization/21705 (FRE does not eliminate a redundant pure call.)

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2005-05-25  Daniel Berlin  <dberlin@dberlin.org>

	Fix PR tree-optimization/21705

	* tree-ssa-pre.c (in_fre): New static variable.
	(create_value_expr_from): Recursively value number reference ops
	in argument lists.
	(can_value_number_call): Temporary restrict only exists for
	PRE, not FRE.

From-SVN: r100156
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Daniel Berlin 2005-05-25 18:53:25 +00:00 committed by Daniel Berlin
parent 14d63fb68e
commit 81def1b74b
3 changed files with 49 additions and 6 deletions
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10
gcc/ChangeLog
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@ -1,3 +1,13 @@
2005-05-25 Daniel Berlin <dberlin@dberlin.org>
Fix PR tree-optimization/21705
* tree-ssa-pre.c (in_fre): New static variable.
(create_value_expr_from): Recursively value number reference ops
in argument lists.
(can_value_number_call): Temporary restrict only exists for
PRE, not FRE.
2005-05-25 Kazu Hirata <kazu@cs.umass.edu>
* tree-into-ssa.c (rewrite_into_ssa, update_ssa): Replace

14
gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-14.c Normal file
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@ -0,0 +1,14 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
extern unsigned int strlen (const char *) __attribute__ ((__pure__));
void
foo (const char *str)
{
unsigned int a = strlen (str);
unsigned int b = strlen (str);
if (a != b)
link_error ();
}
/* { dg-final { scan-tree-dump-times "link_error" 0 "optimized"} } */
/* { dg-final { cleanup-tree-dump "optimized" } } */

31
gcc/tree-ssa-pre.c
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@ -178,6 +178,8 @@ Boston, MA 02111-1307, USA. */
useful only for debugging, since we don't do identity lookups. */
static bool in_fre = false;
/* A value set element. Basically a single linked list of
expressions/values. */
typedef struct value_set_node
@ -2030,17 +2032,32 @@ create_value_expr_from (tree expr, basic_block block, tree stmt)
if (code == TREE_LIST)
{
tree op = NULL_TREE;
tree temp = NULL_TREE;
if (TREE_CHAIN (vexpr))
temp = create_value_expr_from (TREE_CHAIN (vexpr), block, stmt);
TREE_CHAIN (vexpr) = temp ? temp : TREE_CHAIN (vexpr);
/* Recursively value-numberize reference ops. */
if (REFERENCE_CLASS_P (TREE_VALUE (vexpr)))
{
tree tempop;
op = TREE_VALUE (vexpr);
tempop = create_value_expr_from (op, block, stmt);
op = tempop ? tempop : op;
TREE_VALUE (vexpr) = vn_lookup_or_add (op, stmt);
}
else
{
op = TREE_VALUE (vexpr);
TREE_VALUE (vexpr) = vn_lookup_or_add (TREE_VALUE (vexpr), NULL);
}
/* This is the equivalent of inserting op into EXP_GEN like we
do below */
if (!is_undefined_value (TREE_VALUE (vexpr)))
value_insert_into_set (EXP_GEN (block), TREE_VALUE (vexpr));
TREE_VALUE (vexpr) = vn_lookup_or_add (TREE_VALUE (vexpr), NULL);
if (!is_undefined_value (op))
value_insert_into_set (EXP_GEN (block), op);
return vexpr;
}
@ -2108,8 +2125,8 @@ can_value_number_call (tree stmt)
tree call = get_call_expr_in (stmt);
/* This is a temporary restriction until we translate vuses through
phi nodes. */
if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
phi nodes. This is only needed for PRE, of course. */
if (!in_fre && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
return false;
if (call_expr_flags (call) & (ECF_PURE | ECF_CONST))
return true;
@ -2454,6 +2471,8 @@ static void
init_pre (bool do_fre)
{
basic_block bb;
in_fre = do_fre;
inserted_exprs = NULL;
vn_init ();