https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87214
--- Comment #17 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to rsand...@gcc.gnu.org from comment #16)
> Created attachment 45526 [details]
> Passing testcase
>
> I'm still not sure where the problem is coming in. The loop in the vector
> dump looks functionally correct now I've had change to look at it more
> (contrary to my initial comment on IRC). It seems to be equivalent to the
> attached, which passed on an AVX2 box I found I had accesss to.
But it fails on a skylake-avx512 machine. Minimal test-case that fails:
$ cat avx.c
struct s { unsigned long a, b, c; };
void __attribute__ ((noipa))
f (struct s *restrict s1, struct s *restrict s2, int n)
{
for (int i = 0; i < n; ++i)
{
s1[i].b = s2[i].b;
s1[i].c = s2[i].c;
s2[i].c = 0;
}
}
#define N 6
int
main (void)
{
struct s s1[N], s2[N];
for (unsigned int j = 0; j < 6; ++j)
{
s2[j].a = j * 5;
s2[j].b = j * 5 + 2;
s2[j].c = j * 5 + 4;
}
f (s1, s2, 6);
for (unsigned int j = 0; j < 6; ++j)
if (s1[j].b != j * 5 + 2)
{
__builtin_printf ("wrong at: %d: is %d, should be %d\n", j,
s1[j].b, j * 5 + 2);
__builtin_abort ();
}
__builtin_printf ("OK\n");
return 0;
}
$ gcc -march=skylake-avx512 avx.c -g && ./a.out && gcc -march=skylake-avx512
avx.c -g -O3 && ./a.out
OK
wrong at: 3: is 15, should be 17
Aborted (core dumped)
