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re PR rtl-optimization/41917 (Strange athrithmetic result with -O3)

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PR rtl-optimization/41917
	* rtlanal.c (num_sign_bit_copies1) <case UMOD>: If sign bit of second
	operand isn't known to be 0, return 1.

	* gcc.c-torture/execute/pr41917.c: New test.

From-SVN: r153874
This commit is contained in:
Jakub Jelinek 2009-11-03 23:36:39 +01:00 • committed by Jakub Jelinek
parent 0b94d8b285
commit 24d179b4c7
4 changed files with 42 additions and 2 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2009-11-03 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/41917
* rtlanal.c (num_sign_bit_copies1) <case UMOD>: If sign bit of second
operand isn't known to be 0, return 1.
2009-11-03 Richard Sandiford <rdsandiford@googlemail.com>
* config/mips/mips.md: Fix typos.

12
gcc/rtlanal.c
View file

@ -4517,8 +4517,16 @@ num_sign_bit_copies1 (const_rtx x, enum machine_mode mode, const_rtx known_x,
known_x, known_mode, known_ret);
case UMOD:
/* The result must be <= the second operand. */
return cached_num_sign_bit_copies (XEXP (x, 1), mode,
/* The result must be <= the second operand. If the second operand
has (or just might have) the high bit set, we know nothing about
the number of sign bit copies. */
if (bitwidth > HOST_BITS_PER_WIDE_INT)
return 1;
else if ((nonzero_bits (XEXP (x, 1), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
return 1;
else
return cached_num_sign_bit_copies (XEXP (x, 1), mode,
known_x, known_mode, known_ret);
case DIV:

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2009-11-03 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/41917
* gcc.c-torture/execute/pr41917.c: New test.
2009-11-03 Uros Bizjak <ubizjak@gmail.com>
* gcc.target/i386/pr41900.c: Make test compile only. Scan assembler

21
gcc/testsuite/gcc.c-torture/execute/pr41917.c Normal file
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@ -0,0 +1,21 @@
/* PR rtl-optimization/41917 */
extern void abort (void);
unsigned int a = 1;
int
main (void)
{
unsigned int b, c, d;
if (sizeof (int) != 4 || (int) 0xc7d24b5e > 0)
return 0;
c = 0xc7d24b5e;
d = a | -2;
b = (d == 0) ? c : (c % d);
if (b != c)
abort ();
return 0;
}