https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96075
Bug ID: 96075
Summary: bogus alignment for negative step grouped access
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
double x[1024], y[1024];
void __attribute__((noipa)) boo()
{
for (int i = 0; i < 512; ++i)
{
x[2*i] = y[2*(511-i)];
x[2*i+1] = y[2*(511-i)];
}
}
int
main ()
{
for (int i = 0; i < 1024; ++i)
{
x[i] = 0;
y[i] = i;
__asm__ volatile ("");
}
boo ();
for (int i = 0; i < 1024; ++i)
if (x[i] != y[2*(511 - i/2)])
abort ();
return 0;
}
segfaults because we emit
boo:
.LFB8:
.cfi_startproc
xorl %eax, %eax
.p2align 4,,10
.p2align 3
.L21:
movapd y+8168(%rax), %xmm0
movq %rax, %rdx
where this is obviously misaligned.
