On 2023/7/18 14:48, Huacai Chen wrote:
In current configuration, cpu_has_lsx and cpu_has_lasx are impossible
constants. So cleanup the __builtin_constant_p() checking to reduce the
"cannot be constants"? "impossible constants" sounds like a compile-time
error to me.
complexity.
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
arch/loongarch/include/asm/fpu.h | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/arch/loongarch/include/asm/fpu.h b/arch/loongarch/include/asm/fpu.h
index e4193d637f66..f02f4a0d0d64 100644
--- a/arch/loongarch/include/asm/fpu.h
+++ b/arch/loongarch/include/asm/fpu.h
@@ -218,12 +218,7 @@ static inline void restore_lsx(struct task_struct *t)
static inline void init_lsx_upper(void)
{
- /*
- * Check cpu_has_lsx only if it's a constant. This will allow the
- * compiler to optimise out code for CPUs without LSX without adding
- * an extra redundant check for CPUs with LSX.
- */
- if (__builtin_constant_p(cpu_has_lsx) && !cpu_has_lsx)
+ if (!cpu_has_lsx)
return;
_init_lsx_upper();
@@ -294,7 +289,7 @@ static inline void restore_lasx_upper(struct task_struct *t) {}
static inline int thread_lsx_context_live(void)
{
- if (__builtin_constant_p(cpu_has_lsx) && !cpu_has_lsx)
+ if (!cpu_has_lsx)
return 0;
return test_thread_flag(TIF_LSX_CTX_LIVE);
@@ -302,7 +297,7 @@ static inline int thread_lsx_context_live(void)
static inline int thread_lasx_context_live(void)
{
- if (__builtin_constant_p(cpu_has_lasx) && !cpu_has_lasx)
+ if (!cpu_has_lasx)
return 0;
return test_thread_flag(TIF_LASX_CTX_LIVE);
For the foreseeable future, the changes seem appropriate to me. FWIW the
LoongArch kernel would stay as generic as possible so I expect the
various predicates to almost never exist as constants.
Reviewed-by: WANG Xuerui <git@xxxxxxxxxx>
--
WANG "xen0n" Xuerui
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