https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81019
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-11-27
CC| |aoliva at gcc dot gnu.org,
| |segher at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
/* PR rtl-optimization/81019 */
/* { dg-do run } */
/* { dg-options "-O -fno-tree-ccp" } */
unsigned long long __attribute__((noinline, noclone))
foo (unsigned char a, unsigned short b, unsigned c, unsigned long long d,
unsigned char e, unsigned short f, unsigned g, unsigned long long h)
{
g = e;
c &= 0 < d;
b *= d;
g ^= -1;
g &= 1;
c |= 1;
a -= 0 < g;
g >>= 1;
f = b | (f >> b);
return a + c + d + f + g + h;
}
int
main (void)
{
if (foo (0, 0, 0, 0, 0, 0, 0, 0) != 0x100)
__builtin_abort ();
return 0;
}
This is indeed miscompiled in the combiner if the r249850 change is reverted
(which changes costs and thus combiner decides to try different optimizations).
With the change reverted, the g &= 1 masking is lost.
Alex/Segher, what is the current state of the patch?
I see https://gcc.gnu.org/ml/gcc-patches/2017-07/msg00363.html as the last mail
on the subject.
