Messages in this thread | | | From | Dmitry Vyukov <> | Date | Tue, 12 Sep 2017 16:42:56 +0200 | Subject | "KVM: x86: generalize guest_cpuid_has_ helpers" breaks clang |
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Hi Radim,
I've just noticed that your commit "KVM: x86: generalize guest_cpuid_has_ helpers" breaks clang build on this assert:
static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature) { unsigned x86_leaf = x86_feature / 32;
BUILD_BUG_ON(!__builtin_constant_p(x86_leaf));
In clang __builtin_constant_p is never true for function arguments, it's true only for compile-time constants (what you can use as stack array size, or C++ template argument). What would work is an additional macro along the lines of:
#define x86_feature_cpuid(x) (BUILD_BUG_ON(!__builtin_constant_p(x), __x86_feature_cpuid(x))
But again assuming that caller pass the constant directly.
Could you please fix it?
Thanks
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