[PATCH] D21282: AMDGPU: mark {exp, log}10{, f, l} library functions as unavailable

[Nicolai Hähnle via llvm-commits]

nhaehnle added a comment.

I think it's mostly used by SimplifyLibCalls and perhaps other parts of InstCombine to decide whether certain transformations are allowed.

Interestingly, NVPTX sets disableAllFunctions, but there is a comment saying that "having no standard library prevents e.g. many fastmath optimizations". And indeed, on my shader-db using disableAllFunctions() makes a difference. It might be limited to sqrt and abs functions.

I'll commit this change as-is for now, i.e. stick with blacklisting.


http://reviews.llvm.org/D21282