https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111121
Bug ID: 111121
Summary: AArch64: MOPS memmove operand corruption
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: wilco at gcc dot gnu.org
Target Milestone: ---
Since GCC 12.0 the following example corrupts x0 when built with -O2
-march=armv8.6-a+mops:
int *f (int *p, int *q, long n) { memmove (p, q, n); return p; }
f:
cpyp [x0]!, [x1]!, x2!
cpym [x0]!, [x1]!, x2!
cpye [x0]!, [x1]!, x2!
ret
The expansion for memcpy works differently and inserts a copy to a temporary.
-mstrict-align is ignored with small constant-sized memcpy if MOPS is enabled:
void g(int *p, int *q) { memcpy (p, q, 32); }
g:
ldp q0, q1, [x1]
stp q0, q1, [x0]
ret
