https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89229
--- Comment #12 from H.J. Lu <hjl.tools at gmail dot com> ---
[hjl@gnu-4 tmp]$ cat x.c
/* { dg-do compile } */
/* { dg-options "-O2 -march=skylake-avx512" } */
extern int i;
int
foo1 (void)
{
register int xmm16 __asm ("xmm16") = i;
asm volatile ("" : "+v" (xmm16));
register int xmm17 __asm ("xmm17") = xmm16;
asm volatile ("" : "+v" (xmm17));
return xmm17;
}
int
foo2 (void)
{
register int xmm1 __asm ("xmm1") = i;
asm volatile ("" : "+v" (xmm1));
register int xmm17 __asm ("xmm17") = xmm1;
asm volatile ("" : "+v" (xmm17));
return xmm1;
}
/* { dg-final { scan-assembler-not "%zmm\[0-9\]+" } } */
[hjl@gnu-4 tmp]$ gcc -S -O2 -march=skylake-avx512 x.c
[hjl@gnu-4 tmp]$ cat x.s
.file "x.c"
.text
.p2align 4,,15
.globl foo1
.type foo1, @function
foo1:
.LFB0:
.cfi_startproc
vmovd i(%rip), %xmm16
vmovdqa32 %zmm16, %zmm17
vmovd %xmm17, %eax
ret
.cfi_endproc
.LFE0:
.size foo1, .-foo1
.p2align 4,,15
.globl foo2
.type foo2, @function
foo2:
.LFB1:
.cfi_startproc
vmovd i(%rip), %xmm1
vmovdqa32 %zmm1, %zmm17
vmovd %xmm1, %eax
ret
.cfi_endproc
.LFE1:
.size foo2, .-foo2
.ident "GCC: (GNU) 8.2.1 20190209 (Red Hat 8.2.1-8)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-4 tmp]$
