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

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: test/CodeGen/AMDGPU/coalescing-subreg-removed-undef-copy.mir:45-48
+    %23:sreg_32_xm0 = S_MOV_B32 0
+    undef %24.sub0:sreg_128 = COPY %23
+    %24.sub1:sreg_128 = COPY %23
+    %24.sub3:sreg_128 = COPY %23
----------------
You should be able to reduce this to a handful of instructions


Repository:
  rL LLVM

https://reviews.llvm.org/D51257