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re PR middle-end/45262 (Optimization results in wrong result on expression x>>31||(-x)>>31) 

PR middle-end/45262
	* fold-const.c (make_range) <case NEGATE_EXPR>: Punt if
	-a overflows.  Normalize the range.

	* gcc.c-torture/execute/pr45262.c: New test.

From-SVN: r163195
This commit is contained in:
Jakub Jelinek 2010-08-12 17:28:40 +02:00 committed by Jakub Jelinek
parent a89026a168
commit 68bd7fdeac
4 changed files with 48 additions and 3 deletions
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6
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2010-08-12 Jakub Jelinek <jakub@redhat.com>
PR middle-end/45262
* fold-const.c (make_range) <case NEGATE_EXPR>: Punt if
-a overflows. Normalize the range.
2010-08-10 Steve Ellcey <sje@cup.hp.com>
Jakub Jelinek <jakub@redhat.com>

7
gcc/fold-const.c
View File

@ -4479,9 +4479,9 @@ make_range (tree exp, int *pin_p, tree *plow, tree *phigh,
n_high = range_binop (MINUS_EXPR, exp_type,
build_int_cst (exp_type, 0),
0, low, 0);
low = n_low, high = n_high;
exp = arg0;
continue;
if (n_high != 0 && TREE_OVERFLOW (n_high))
break;
goto normalize;
case BIT_NOT_EXPR:
/* ~ X -> -X - 1 */
@ -4514,6 +4514,7 @@ make_range (tree exp, int *pin_p, tree *plow, tree *phigh,
if (TYPE_OVERFLOW_UNDEFINED (arg0_type))
*strict_overflow_p = true;
normalize:
/* Check for an unsigned range which has wrapped around the maximum
value thus making n_high < n_low, and normalize it. */
if (n_low && n_high && tree_int_cst_lt (n_high, n_low))

5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2010-08-12 Jakub Jelinek <jakub@redhat.com>
PR middle-end/45262
* gcc.c-torture/execute/pr45262.c: New test.
2010-08-10 Steve Ellcey <sje@cup.hp.com>
Backport from mainline:

33
gcc/testsuite/gcc.c-torture/execute/pr45262.c Normal file
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@ -0,0 +1,33 @@
/* PR middle-end/45262 */
extern void abort (void);
int
foo (unsigned int x)
{
return ((int) x < 0) || ((int) (-x) < 0);
}
int
bar (unsigned int x)
{
return x >> 31 || (-x) >> 31;
}
int
main (void)
{
if (foo (1) != 1)
abort ();
if (foo (0) != 0)
abort ();
if (foo (-1) != 1)
abort ();
if (bar (1) != 1)
abort ();
if (bar (0) != 0)
abort ();
if (bar (-1) != 1)
abort ();
return 0;
}