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re PR tree-optimization/51877 (XEmacs miscompilation due to tail merging)

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PR tree-optimization/51877
	* tree-ssa-tail-merge.c (gimple_equal_p): Don't return true whenever
	call arguments and fndecls compare equal, instead return false if they
	don't.  Return true only if lhs1 and lhs2 are either both NULL, or
	both SSA_NAMEs that are valueized the same, or they satisfy
	operand_equal_p.

	* gcc.c-torture/execute/pr51877.c: New test.

From-SVN: r183237
This commit is contained in:
Jakub Jelinek 2012-01-17 11:38:38 +01:00 committed by Jakub Jelinek
parent 6521d80a9b
commit e6fa9204e6
4 changed files with 74 additions and 6 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2012-01-17 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/51877
* tree-ssa-tail-merge.c (gimple_equal_p): Don't return true whenever
call arguments and fndecls compare equal, instead return false if they
don't. Return true only if lhs1 and lhs2 are either both NULL, or
both SSA_NAMEs that are valueized the same, or they satisfy
operand_equal_p.
2012-01-17 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
* configure.ac (gcc_cv_target_dl_iterate_phdr): Only check on

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2012-01-17 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/51877
* gcc.c-torture/execute/pr51877.c: New test.
2012-01-17 Michael Zolotukhin <michael.v.zolotukhin@intel.com>
* gcc.dg/vect/no-section-anchors-vect-69.c: Change

50
gcc/testsuite/gcc.c-torture/execute/pr51877.c Normal file
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@ -0,0 +1,50 @@
/* PR tree-optimization/51877 */
extern void abort (void);
struct A { int a; char b[32]; } a, b;
__attribute__((noinline, noclone))
struct A
bar (int x)
{
struct A r;
static int n;
r.a = ++n;
__builtin_memset (r.b, 0, sizeof (r.b));
r.b[0] = x;
return r;
}
__attribute__((noinline, noclone))
void
baz (void)
{
asm volatile ("" : : : "memory");
}
__attribute__((noinline, noclone))
void
foo (struct A *x, int y)
{
if (y == 6)
a = bar (7);
else
*x = bar (7);
baz ();
}
int
main ()
{
a = bar (3);
b = bar (4);
if (a.a != 1 || a.b[0] != 3 || b.a != 2 || b.b[0] != 4)
abort ();
foo (&b, 0);
if (a.a != 1 || a.b[0] != 3 || b.a != 3 || b.b[0] != 7)
abort ();
foo (&b, 6);
if (a.a != 4 || a.b[0] != 7 || b.a != 3 || b.b[0] != 7)
abort ();
return 0;
}

16
gcc/tree-ssa-tail-merge.c
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@ -1,5 +1,5 @@
/* Tail merging for gimple.
Copyright (C) 2011 Free Software Foundation, Inc.
Copyright (C) 2011, 2012 Free Software Foundation, Inc.
Contributed by Tom de Vries (tom@codesourcery.com)
This file is part of GCC.
@ -1071,14 +1071,18 @@ gimple_equal_p (same_succ same_succ, gimple s1, gimple s2)
equal = false;
break;
}
if (equal)
return true;
if (!equal)
return false;
lhs1 = gimple_get_lhs (s1);
lhs2 = gimple_get_lhs (s2);
return (lhs1 != NULL_TREE && lhs2 != NULL_TREE
&& TREE_CODE (lhs1) == SSA_NAME && TREE_CODE (lhs2) == SSA_NAME
&& vn_valueize (lhs1) == vn_valueize (lhs2));
if (lhs1 == NULL_TREE && lhs2 == NULL_TREE)
return true;
if (lhs1 == NULL_TREE || lhs2 == NULL_TREE)
return false;
if (TREE_CODE (lhs1) == SSA_NAME && TREE_CODE (lhs2) == SSA_NAME)
return vn_valueize (lhs1) == vn_valueize (lhs2);
return operand_equal_p (lhs1, lhs2, 0);
case GIMPLE_ASSIGN:
lhs1 = gimple_get_lhs (s1);