Merging r316181:

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r316181 | jvesely | 2017-10-19 13:40:13 -0700 (Thu, 19 Oct 2017) | 4 lines

AMDGPU: Parse r600 CPU name early and expose FMAF capability

Improve amdgcn macro test
Differential Revision: https://reviews.llvm.org/D38667
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llvm-svn: 319032