https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90073
--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
The problem is with the default -mtune=generic.
[hjl@gnu-cfl-1 gcc]$ cat /tmp/foo.cc
#include <x86intrin.h>
using data = long long __attribute__((vector_size(64)));
void f(data& a, const data& x1, const data& x2) {
a ^= x1 ^ x2;
}
[hjl@gnu-cfl-1 gcc]$ ./xgcc -B./ -O3 -mtune=skylake -mavx2 /tmp/foo.cc -S
[hjl@gnu-cfl-1 gcc]$ cat foo.s
.file "foo.cc"
.text
.p2align 4
.globl _Z1fRDv8_xRKS_S2_
.type _Z1fRDv8_xRKS_S2_, @function
_Z1fRDv8_xRKS_S2_:
.LFB5519:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
andq $-64, %rsp
subq $200, %rsp
vmovdqa (%rsi), %ymm2
vmovdqa 32(%rsi), %ymm0
vpxor (%rdx), %ymm2, %ymm1
vpxor 32(%rdx), %ymm0, %ymm0
vpxor (%rdi), %ymm1, %ymm1
vpxor 32(%rdi), %ymm0, %ymm0
vmovaps %ymm1, (%rdi)
vmovaps %ymm0, 32(%rdi)
vzeroupper
leave
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE5519:
.size _Z1fRDv8_xRKS_S2_, .-_Z1fRDv8_xRKS_S2_
.ident "GCC: (GNU) 9.0.1 20190412 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-cfl-1 gcc]$
