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re PR tree-optimization/48694 (possible memory hog bug)

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2011-04-26  Richard Guenther  <rguenther@suse.de>

	PR middle-end/48694
	* tree.h (OEP_CONSTANT_ADDRESS_OF): New operand_equal_flag.
	* fold-const.c (operand_equal_p): For TREE_CONSTANT ADDR_EXPRs
	compare the operands with OEP_CONSTANT_ADDRESS_OF.  Treat
	trees with TREE_SIDE_EFFECTS equal when OEP_CONSTANT_ADDRESS_OF
	is set.

	* gcc.dg/torture/pr48694-1.c: New testcase.
	* gcc.dg/torture/pr48694-2.c: Likewise.

From-SVN: r172954
This commit is contained in:
Richard Guenther 2011-04-26 09:21:44 +00:00 committed by Richard Biener
parent 0d467c0bf2
commit ad0e2567d6
5 changed files with 48 additions and 3 deletions

8
gcc/fold-const.c

@ -2473,9 +2473,12 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
equal if they have no side effects. If we have two identical
expressions with side effects that should be treated the same due
to the only side effects being identical SAVE_EXPR's, that will
be detected in the recursive calls below. */
be detected in the recursive calls below.
If we are taking an invariant address of two identical objects
they are necessarily equal as well. */
if (arg0 == arg1 && ! (flags & OEP_ONLY_CONST)
&& (TREE_CODE (arg0) == SAVE_EXPR
|| (flags & OEP_CONSTANT_ADDRESS_OF)
|| (! TREE_SIDE_EFFECTS (arg0) && ! TREE_SIDE_EFFECTS (arg1))))
return 1;
@ -2538,7 +2541,8 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
case ADDR_EXPR:
return operand_equal_p (TREE_OPERAND (arg0, 0), TREE_OPERAND (arg1, 0),
0);
TREE_CONSTANT (arg0) && TREE_CONSTANT (arg1)
? OEP_CONSTANT_ADDRESS_OF : 0);
default:
break;
}

6
gcc/testsuite/ChangeLog

@ -1,3 +1,9 @@
2011-04-26 Richard Guenther <rguenther@suse.de>
PR middle-end/48694
* gcc.dg/torture/pr48694-1.c: New testcase.
* gcc.dg/torture/pr48694-2.c: Likewise.
2011-04-25 Paolo Carlini <paolo.carlini@oracle.com>
* g++.dg/ext/underlying_type1.C: New.

14
gcc/testsuite/gcc.dg/torture/pr48694-1.c Normal file

@ -0,0 +1,14 @@
/* { dg-do compile } */
extern volatile int g_89[5][9];
extern int g, *gp;
void func_64()
{
int i;
for (i = 0; i < 1; )
{
for (g = 0; g < 1; )
return;
gp = (int *)&g_89[g][0];
}
}

20
gcc/testsuite/gcc.dg/torture/pr48694-2.c Normal file

@ -0,0 +1,20 @@
/* { dg-do compile } */
extern volatile int g_4[1][4];
extern int g_7;
void modify(int *);
void func_2()
{
int l_46 = 4;
if (g_7)
modify(&l_46);
else
{
int i;
for (i = 0; i != 5; i += 1)
{
volatile int *vp = &g_4[0][l_46];
*vp = 0;
}
}
}

3
gcc/tree.h

@ -5118,7 +5118,8 @@ extern tree fold_fma (location_t, tree, tree, tree, tree);
enum operand_equal_flag
{
OEP_ONLY_CONST = 1,
OEP_PURE_SAME = 2
OEP_PURE_SAME = 2,
OEP_CONSTANT_ADDRESS_OF = 4
};
extern int operand_equal_p (const_tree, const_tree, unsigned int);