https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126959
Bug ID: 126959
Summary: -march=znver4 prefers load from memory for mask
register
Product: gcc
Version: 16.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
Target Milestone: ---
Target: x86
[hjl@gnu-tgl-3 tmp]$ cat x.c
void
foo (void)
{
unsigned short int k = 0;
__asm volatile ("" : : "k" (k));
k = -1;
__asm volatile ("" : : "k" (k));
}
[hjl@gnu-tgl-3 tmp]$ gcc -S -O2 -march=tigerlake x.c
[hjl@gnu-tgl-3 tmp]$ cat x.s
.file "x.c"
.text
.p2align 4
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
kxorw %k0, %k0, %k0
kxnorw %k1, %k1, %k1
ret
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (GNU) 16.2.1 20260807 (Red Hat 16.2.1-1)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tgl-3 tmp]$ gcc -S -O2 -march=znver4 x.c
[hjl@gnu-tgl-3 tmp]$ cat x.s
.file "x.c"
.text
.p2align 4
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
kxorw %k0, %k0, %k0
kmovw .LC0(%rip), %k1
ret
.cfi_endproc
.LFE0:
.size foo, .-foo
.section .rodata.cst2,"aM",@progbits,2
.align 2
.LC0:
.value -1
.ident "GCC: (GNU) 16.2.1 20260807 (Red Hat 16.2.1-1)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tgl-3 tmp]$
