From: Maciej W. Rozycki Date: Fri, 3 Apr 2015 22:25:00 +0000 (+0100) Subject: MIPS: bitops.h: Avoid inline asm for constant FLS X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=cb5d4aad6844cdbe2f3b9f5d581ae1c9ec342009;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git MIPS: bitops.h: Avoid inline asm for constant FLS GCC is smart enough to substitute the final result for FLS calculations as implemented in the fallback C code we have in `__fls' and `fls' applied to constant values. The presence of inline asm defeats the compiler though, forcing it to emit extraneous CLZ/DCLZ calculation for processors that support these instructions. Use `__builtin_constant_p' then to avoid inline asm altogether for constants. Signed-off-by: Maciej W. Rozycki Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9681/ Signed-off-by: Ralf Baechle --- diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h index 9f935f6aa996..0cf29bd5dc5c 100644 --- a/arch/mips/include/asm/bitops.h +++ b/arch/mips/include/asm/bitops.h @@ -481,7 +481,7 @@ static inline unsigned long __fls(unsigned long word) { int num; - if (BITS_PER_LONG == 32 && + if (BITS_PER_LONG == 32 && !__builtin_constant_p(word) && __builtin_constant_p(cpu_has_clo_clz) && cpu_has_clo_clz) { __asm__( " .set push \n" @@ -494,7 +494,7 @@ static inline unsigned long __fls(unsigned long word) return 31 - num; } - if (BITS_PER_LONG == 64 && + if (BITS_PER_LONG == 64 && !__builtin_constant_p(word) && __builtin_constant_p(cpu_has_mips64) && cpu_has_mips64) { __asm__( " .set push \n" @@ -559,7 +559,8 @@ static inline int fls(int x) { int r; - if (__builtin_constant_p(cpu_has_clo_clz) && cpu_has_clo_clz) { + if (!__builtin_constant_p(x) && + __builtin_constant_p(cpu_has_clo_clz) && cpu_has_clo_clz) { __asm__( " .set push \n" " .set "MIPS_ISA_LEVEL" \n"