https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78266
--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Minimal example:
...
int
main ()
{
#pragma acc parallel num_gangs(256)
{
#pragma acc loop gang
for (unsigned char j = 0; j < 5; j++)
;
}
return 0;
}
...
We generate an unconditional trap, thanks to pass_isolate_erroneous_paths:
...
.entry main$_omp_fn$0 (.param .u64 %in_ar0)
{
.reg .u64 %ar0;
ld.param.u64 %ar0,[%in_ar0];
.reg .pred %r23;
{
.reg .u32 %x;
mov.u32 %x,%tid.x;
setp.ne.u32 %r23,%x,0;
}
@ %r23 bra $L2;
trap;
$L2:
}
...
AFAICT, the problem is that the logic that distributes the iterations over the
gangs uses signed char, while the number of gangs can be larger than what is
representable.
