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Date: Tue, 1 May 2007 05:58:10 +0200 (CEST) From: Andi Kleen <ak@...e.de> To: patches@...-64.org, linux-kernel@...r.kernel.org Subject: [PATCH] [13/30] 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 <ak@...e.de> --- include/asm-i386/cpufeature.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) Index: linux/include/asm-i386/cpufeature.h =================================================================== --- linux.orig/include/asm-i386/cpufeature.h +++ linux/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) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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