https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105463
Bug ID: 105463
Summary: [12/13 Regression] MVE: Wrong code, incorrect
alignment assumption
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: acoplan at gcc dot gnu.org
Target Milestone: ---
The following code is reduced from gcc.c-torture/execute/pr65369.c:
void foo (unsigned *);
void bar (const unsigned char *block)
{
unsigned buf[4];
__builtin_memcpy (buf + 0, block + 0, 4);
__builtin_memcpy (buf + 1, block + 4, 4);
__builtin_memcpy (buf + 2, block + 8, 4);
__builtin_memcpy (buf + 3, block + 12, 4);
foo (buf);
}
and it is miscompiled, starting in GCC 12, for MVE (with
-march=armv8.1-m.main+mve -O2). We generate:
bar:
mov r3, r0
push {lr}
sub sp, sp, #20
mov r0, sp
vldrw.32 q3, [r3]
vstrw.32 q3, [r0]
bl foo
add sp, sp, #20
ldr pc, [sp], #4
where vldrw.32 requires a 4-byte aligned address, but the source of course has
no such requirement: memcpy does not require an aligned address.
