[all-commits] [llvm/llvm-project] 1aec3d: [SystemZ][z/OS] Save (and restore) R3 to avoid clo...

[Neumann Hon via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1aec3d15aaa25c39fae026688708d7353d488974
      https://github.com/llvm/llvm-project/commit/1aec3d15aaa25c39fae026688708d7353d488974
  Author: Neumann Hon <neumann.hon at ibm.com>
  Date:   2023-05-11 (Thu, 11 May 2023)

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

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

When the stack frame extension routine is used, the contents of r3 is
overwritten. However, if r3 is live in the prologue (ie. one of the
function's parameters resides in r3), it needs to be saved. We save
r3 in r0 if r0 is available (ie. r0 is not used as temporary storage
for r4), and in the corresponding stack slot for the third parameter otherwise.

Reviewed By: uweigand

Differential Revision: https://reviews.llvm.org/D150332