[PATCH] D51257: [RegisterCoalescer] Do not eliminateUndefCopy for a partial copy

[Tim Renouf via Phabricator via llvm-commits]

tpr created this revision.
Herald added subscribers: llvm-commits, nhaehnle, jvesely, qcolombet, MatzeB.

eliminateUndefCopy was incorrectly eliminating a copy that was only a
partial write of the target. In the test case, the resulting incorrect
live range caused a subrange join unreachable later.

The test case does not fail for me until I have https://reviews.llvm.org/D49097.

Change-Id: Ibb767d8a016934431660764b0194634e2113fea2


Repository:
  rL LLVM

https://reviews.llvm.org/D51257

Files:
  lib/CodeGen/RegisterCoalescer.cpp
  test/CodeGen/AMDGPU/coalescing-subreg-removed-undef-copy.mir

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D51257.162550.patch
Type: text/x-patch
Size: 6518 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180825/0b09d7c9/attachment.bin>