[PATCH] D26335: [ms] Reinstate https://reviews.llvm.org/D14748 after https://reviews.llvm.org/D20291

[Paul Robinson via cfe-commits]

probinson added inline comments.


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Comment at: lib/Headers/x86intrin.h:49
+static __inline__ unsigned int __attribute__((__always_inline__, __nodebug__))
+__tzcnt_u32(unsigned int __X) { return __X ? __builtin_ctz(__X) : 32; }
+#ifdef __x86_64__
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hans wrote:
> I'm worried about the conditional here. IIRC, ffmpeg uses TZCNT just as a faster encoding for BSF, but now we're putting a conditional in the way, so this will be slower actually. On the other hand, the alternative is weird too :-/
I thought there was a peephole to notice a guard like this and do the right thing? In which case having the guard is fine.


https://reviews.llvm.org/D26335