x86, cpufeature: Unbreak compile with gcc 3.x
H. Peter Anvin [Thu, 27 May 2010 19:02:00 +0000 (12:02 -0700)]
gcc 3 is too braindamaged to be able to compile static_cpu_has() --
apparently it can't tell that a constant passed to an inline function
is still a constant -- so if we're using gcc 3, just use the dynamic
test.  This is bad for performance, but if you care about performance,
don't use an ancient, known-to-optimize-poorly compiler.

Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
LKML-Reference: <4BF2FF82.7090005@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/cpufeature.h

index dca9c54..4681459 100644 (file)
@@ -332,6 +332,7 @@ static __always_inline __pure bool __static_cpu_has(u8 bit)
 #endif
 }
 
+#if __GNUC__ >= 4
 #define static_cpu_has(bit)                                    \
 (                                                              \
        __builtin_constant_p(boot_cpu_has(bit)) ?               \
@@ -340,6 +341,12 @@ static __always_inline __pure bool __static_cpu_has(u8 bit)
                __static_cpu_has(bit) :                         \
                boot_cpu_has(bit)                               \
 )
+#else
+/*
+ * gcc 3.x is too stupid to do the static test; fall back to dynamic.
+ */
+#define static_cpu_has(bit) boot_cpu_has(bit)
+#endif
 
 #endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */