linux-kernel - [PATCH] LoongArch: Cleanup __builtin_constant_p() checking for cpu_has

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Date:   Tue, 18 Jul 2023 14:48:19 +0800
From:   Huacai Chen <chenhuacai@...ngson.cn>
To:     Huacai Chen <chenhuacai@...nel.org>
Cc:     loongarch@...ts.linux.dev, linux-arch@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-kernel@...r.kernel.org, loongson-kernel@...ts.loongnix.cn,
        Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH] LoongArch: Cleanup __builtin_constant_p() checking for cpu_has_*

In current configuration, cpu_has_lsx and cpu_has_lasx are impossible
constants. So cleanup the __builtin_constant_p() checking to reduce the
complexity.

Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 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);
-- 
2.39.3