Merging r268259:

Merging r268259:

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r268259 | nhaehnle | 2016-05-02 10:37:01 -0700 (Mon, 02 May 2016) | 14 lines

AMDGPU: llvm.SI.fs.constant is a source of divergence

Summary:
This intrinsic is used to get flat-shaded fragment shader inputs. Those are
uniform across a primitive, but a fragment shader wave may process pixels from
multiple primitives (as indicated by the prim_mask), and so that's where
divergence can arise.

Reviewers: arsenm, tstellarAMD

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D19747

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_38@271769 91177308-0d34-0410-b5e6-96231b3b80d8