[all-commits] [llvm/llvm-project] 86f911: AMDGPU: Don't report 2-byte alignment as fast

[Matt Arsenault via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 86f9117d476bcef2f5e0eabae4781e99877ce7b5
      https://github.com/llvm/llvm-project/commit/86f9117d476bcef2f5e0eabae4781e99877ce7b5
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2020-02-11 (Tue, 11 Feb 2020)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIISelLowering.cpp
    M llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
    M llvm/test/CodeGen/AMDGPU/chain-hi-to-lo.ll
    A llvm/test/CodeGen/AMDGPU/fast-unaligned-load-store.global.ll
    A llvm/test/CodeGen/AMDGPU/fast-unaligned-load-store.private.ll
    M llvm/test/CodeGen/AMDGPU/unaligned-load-store.ll
    M llvm/test/Transforms/LoadStoreVectorizer/AMDGPU/adjust-alloca-alignment.ll
    M llvm/test/Transforms/LoadStoreVectorizer/AMDGPU/merge-stores-private.ll
    M llvm/test/Transforms/LoadStoreVectorizer/AMDGPU/merge-stores.ll

  Log Message:
  -----------
  AMDGPU: Don't report 2-byte alignment as fast

This is apparently worse than 1-byte alignment. This does not attempt
to decompose 2-byte aligned wide stores, but will stop trying to
produce them.

Also fix bug in LoadStoreVectorizer which was decreasing the alignment
and vectorizing stack accesses. It was assuming a stack object was an
alloca that could have its base alignment changed, which is not true
if the pointer is derived from a function argument.