https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102105
Bug ID: 102105
Summary: x86_64: ABI break with vector in union and -mno-mmx
-mavx
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: mpolacek at gcc dot gnu.org
Target Milestone: ---
This looks like another ABI break. Started with r271213.
-mno-mmx -mavx is an unusual combination I guess, but I'm filing this anyway.
$ cat m.c
void vector_1_x();
int main() { vector_1_x(); }
$ cat x.c
typedef int di;
typedef di __attribute__((vector_size(8))) v1di;
typedef union {
v1di v;
di a[1];
} u1di;
v1di g_v1di;
int pass_v1di_j;
di pass_v1di_a[1];
di pass_v1di_a_0;
u1di pass_v1di_u;
void test_v8qi();
void pass_v8qi() {}
void test_v1di();
void checkp_1di();
void pass_v1di(v1di v) {
pass_v1di_u.v = v;
pass_v1di_a_0 = pass_v1di_u.a[pass_v1di_j];
checkp_1di(pass_v1di_a);
}
void vector_1_x() {
test_v8qi();
test_v1di();
}
$ cat y.c
typedef int qi;
typedef int __attribute__((mode(DI))) di;
int test_v8qi_i, checkp_1di_i;
extern __attribute__((__vector_size__(sizeof(di)))) di g_v1di;
void abort();
typedef union {
__attribute__((__vector_size__(2 * sizeof(qi)))) qi v;
qi a[8];
} u8qi;
void pass_v8qi();
void checkp_8qi(qi *p) {
for (; 0;)
if (p)
abort();
}
void test_v8qi() {
u8qi u;
qi *p = u.a;
for (; test_v8qi_i;)
u.a[test_v8qi_i] = test_v8qi_i;
pass_v8qi(u.v);
checkp_8qi(p);
}
void pass_v1di();
void checkp_1di(di *p) {
if (p[checkp_1di_i])
abort();
}
void test_v1di() { pass_v1di(g_v1di); }
And then:
$ xgcc-11 -c m.c
$ xgcc-11 -c x.c -mno-mmx -mavx
$ xgcc-9 -c y.c -mno-mmx -mavx
$ xgcc-11 m.o x.o y.o -o foo
$ ./foo
Aborted (core dumped)
$ xgcc-10 -c y.c -mno-mmx -mavx
$ xgcc-11 m.o x.o y.o -o foo
$ ./foo && echo ok
ok
