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From: tip-bot for H. Peter Anvin on 27 May 2010 16:20
Commit-ID: 1ba4f22c426ba04b00fd717318d50620c621a0e1
Gitweb: http://git.kernel.org/tip/1ba4f22c426ba04b00fd717318d50620c621a0e1
Author: H. Peter Anvin <hpa(a)linux.intel.com>
AuthorDate: Thu, 27 May 2010 12:02:00 -0700
Committer: H. Peter Anvin <hpa(a)linux.intel.com>
CommitDate: Thu, 27 May 2010 12:02:00 -0700

x86, cpufeature: Unbreak compile with gcc 3.x

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(a)gmail.com>
LKML-Reference: <4BF2FF82.7090005(a)zytor.com>
Signed-off-by: H. Peter Anvin <hpa(a)linux.intel.com>
---
arch/x86/include/asm/cpufeature.h | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index dca9c54..4681459 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -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__) */

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