[PATCH] D150332: [SystemZ][z/OS] Save (and restore) R3 to avoid clobbering parameter when call stack frame extension is invoked

[Neumann Hon via Phabricator via llvm-commits]

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When the stack frame extension routine is used, the contents of R3 <https://reviews.llvm.org/source/clang/> is overwritten. However, if R3 <https://reviews.llvm.org/source/clang/> is live in the prologue (ie. one of the function's parameters resides in R3 <https://reviews.llvm.org/source/clang/>), it needs to be saved. We save R3 <https://reviews.llvm.org/source/clang/> in R0 if R0 is available (ie. R0 is not used as temporary storage for R4 <https://reviews.llvm.org/source/lld/>), and in the corresponding stack slot for the third parameter otherwise.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D150332

Files:
  llvm/lib/Target/SystemZ/SystemZFrameLowering.cpp
  llvm/test/CodeGen/SystemZ/zos-prologue-epilog.ll

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