[PATCH] D140045: [X86] Move RDFLAGS/WRFLAGS expansion until after RA

[Bill Wendling via Phabricator via llvm-commits]

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The register allocator may introduce reloads in the middle of reading
and writing the EFLAGS register, due to the RDFLAGS & WRFLAGS pseudos
being expanded before RA. This may cause an issue where the stack
pointer was adjusted but the stack offset for the reload wasn't
accounted for (see [1]).

To avoid this, expand these pseudos after register allocation.

[1] https://github.com/llvm/llvm-project/issues/59102


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140045

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/lib/Target/X86/X86InstrInfo.cpp
  llvm/lib/Target/X86/X86InstrInfo.td
  llvm/test/CodeGen/X86/eflags.ll

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