[PATCH] D102342: [SPARC] Fix register reuse in leaf function remapping step

[LemonBoy via Phabricator via llvm-commits]

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Leaf functions allow the compiler to omit the setup and teardown of a frame pointer, therefore avoiding the exchange of the in/out register. According to the SPARC architecture manual every reference to `%i0-%i5` should be replaced with `%o0-o5`, if the target register is already in use a further remapping step to `%g1-%g7` is required to free the output register.

Add a simple check to make sure not to stomp on any output register that's already in use.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D102342

Files:
  llvm/lib/Target/Sparc/SparcFrameLowering.cpp
  llvm/lib/Target/Sparc/SparcFrameLowering.h
  llvm/test/CodeGen/SPARC/leafproc.ll

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