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re PR tree-optimization/56899 (Wrong constant folding)

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PR tree-optimization/56899
	* fold-const.c (extract_muldiv_1): Apply distributive law
	only if TYPE_OVERFLOW_WRAPS (ctype).

	* gcc.c-torture/execute/pr56899.c: New test.

From-SVN: r197692
This commit is contained in:
Jakub Jelinek 2013-04-11 09:30:20 +02:00 committed by Jakub Jelinek
parent b8578ff77f
commit 146b8692e3
4 changed files with 62 additions and 2 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2013-04-11 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/56899
* fold-const.c (extract_muldiv_1): Apply distributive law
only if TYPE_OVERFLOW_WRAPS (ctype).
2013-04-11 Bin Cheng <bin.cheng@arm.com>
PR target/56124

6
gcc/fold-const.c
View File

@ -5850,8 +5850,10 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
/* The last case is if we are a multiply. In that case, we can
apply the distributive law to commute the multiply and addition
if the multiplication of the constants doesn't overflow. */
if (code == MULT_EXPR)
if the multiplication of the constants doesn't overflow
and overflow is defined. With undefined overflow
op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
if (code == MULT_EXPR && TYPE_OVERFLOW_WRAPS (ctype))
return fold_build2 (tcode, ctype,
fold_build2 (code, ctype,
fold_convert (ctype, op0),

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2013-04-11 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/56899
* gcc.c-torture/execute/pr56899.c: New test.
2013-04-10 David S. Miller <davem@davemloft.net>
* gcc.target/sparc/setcc-4.c: New test.

47
gcc/testsuite/gcc.c-torture/execute/pr56899.c Normal file
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@ -0,0 +1,47 @@
/* PR tree-optimization/56899 */
#if __SIZEOF_INT__ == 4 && __CHAR_BIT__ == 8
__attribute__((noinline, noclone)) void
f1 (int v)
{
int x = -214748365 * (v - 1);
if (x != -1932735285)
__builtin_abort ();
}
__attribute__((noinline, noclone)) void
f2 (int v)
{
int x = 214748365 * (v + 1);
if (x != -1932735285)
__builtin_abort ();
}
__attribute__((noinline, noclone)) void
f3 (unsigned int v)
{
unsigned int x = -214748365U * (v - 1);
if (x != -1932735285U)
__builtin_abort ();
}
__attribute__((noinline, noclone)) void
f4 (unsigned int v)
{
unsigned int x = 214748365U * (v + 1);
if (x != -1932735285U)
__builtin_abort ();
}
#endif
int
main ()
{
#if __SIZEOF_INT__ == 4 && __CHAR_BIT__ == 8
f1 (10);
f2 (-10);
f3 (10);
f4 (-10U);
#endif
return 0;
}