[PATCH] D26687: RegisterCoalscer: Only coalesce complete reserved registers.

Tue Nov 15 11:49:12 PST 2016

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The coalescer eliminates copies from reserved registers of the form:

  %vregX = COPY %rY

when %rY is a reserved physreg. However this transformation may be invalid if %rY has non-reserved subregister for which we will miss liveness information. Be conservative in this case and do not coalesce.

The test requires https://reviews.llvm.org/D26648 to work.

Repository:
  rL LLVM

https://reviews.llvm.org/D26687

Files:
  lib/CodeGen/RegisterCoalescer.cpp
  test/CodeGen/AArch64/regcoal-constreg.mir
  test/CodeGen/AArch64/regcoal-physreg.mir

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