From 3671df8572a299acff9c9cac2bf7279ee614d154 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 2 May 2007 19:27:20 +0200 Subject: [PATCH] i386: Evaluate constant cpu features at runtime Redefine cpu_has() to evaluate cpu features already checked in early boot at compile time. This way the compiler might eliminate some dead code. Signed-off-by: Andi Kleen --- include/asm-i386/cpufeature.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h index e66d004aa651..20e849ae6ddc 100644 --- a/include/asm-i386/cpufeature.h +++ b/include/asm-i386/cpufeature.h @@ -106,8 +106,12 @@ #define X86_FEATURE_LAHF_LM (6*32+ 0) /* LAHF/SAHF in long mode */ #define X86_FEATURE_CMP_LEGACY (6*32+ 1) /* If yes HyperThreading not valid */ -#define cpu_has(c, bit) test_bit(bit, (c)->x86_capability) -#define boot_cpu_has(bit) test_bit(bit, boot_cpu_data.x86_capability) +#define cpu_has(c, bit) \ + ((__builtin_constant_p(bit) && (bit) < 32 && \ + (1UL << (bit)) & REQUIRED_MASK1) ? \ + 1 : \ + test_bit(bit, (c)->x86_capability)) +#define boot_cpu_has(bit) cpu_has(&boot_cpu_data, bit) #define cpu_has_fpu boot_cpu_has(X86_FEATURE_FPU) #define cpu_has_vme boot_cpu_has(X86_FEATURE_VME) -- cgit v1.2.3-59-g8ed1b