https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120426
Bug ID: 120426
Summary: XMM store isn't used
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
CC: liuhongt at gcc dot gnu.org
Target Milestone: ---
Target: x86-64
[hjl@gnu-zen4-1 pr117839]$ cat dl-1.c
struct __pthread_mutex_s
{
int __lock;
unsigned int __count;
int __owner;
unsigned int __nusers;
int __kind;
short __spins;
short __elision;
void *p[2];
};
typedef union
{
struct __pthread_mutex_s __data;
char __size[40];
long int __align;
} pthread_mutex_t;
typedef struct { pthread_mutex_t mutex; } __rtld_lock_recursive_t;
void
foo (__rtld_lock_recursive_t *lock)
{
*lock = (__rtld_lock_recursive_t) {{ { 0, 0, 0, 0, 1,
0, 0, { ((void *)0) , ((void *)0) } } }};
}
[hjl@gnu-zen4-1 pr117839]$ make dl-1.s
/export/build/gnu/tools-build/gcc-debug/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/tools-build/gcc-debug/build-x86_64-linux/gcc/ -O2 -fPIC -S
dl-1.c
[hjl@gnu-zen4-1 pr117839]$ make dl-1-spr.s
/export/build/gnu/tools-build/gcc-debug/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/tools-build/gcc-debug/build-x86_64-linux/gcc/ -O2 -fPIC
-mtune=sapphirerapids -S -o dl-1-spr.s dl-1.c
[hjl@gnu-zen4-1 pr117839]$ cat dl-1.s
.file "dl-1.c"
.text
.p2align 4
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
pxor %xmm0, %xmm0
movq $0, 32(%rdi)
movups %xmm0, 16(%rdi)
movups %xmm0, (%rdi)
movl $1, 16(%rdi)
ret
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (GNU) 16.0.0 20250524 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-zen4-1 pr117839]$ cat dl-1-spr.s
.file "dl-1.c"
.text
.p2align 4
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
pxor %xmm0, %xmm0
movq $0, (%rdi)
movq $0, 8(%rdi)
movq $1, 16(%rdi)
movups %xmm0, 24(%rdi)
ret
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (GNU) 16.0.0 20250524 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-zen4-1 pr117839]$
The optimized code should be
pxor %xmm0, %xmm0
movups %xmm0, (%rdi)
movq $1, 16(%rdi)
movups %xmm0, 24(%rdi)
