[PATCH] D73475: [X86] Make sure we do not clobber RBX with mwaitx when used as a base pointer.

[pierre gousseau via Phabricator via llvm-commits]

pgousseau created this revision.
pgousseau added reviewers: qcolombet, filcab, GGanesh, RKSimon, rob.lougher, andreadb, craig.topper.
Herald added subscribers: llvm-commits, jfb, hiraditya.
Herald added a project: LLVM.

mwaitx uses EBX as one of its argument.
Using this instruction clobbers RBX as it is defined to hold one of the input. When the backend uses dynamically allocated stack, RBX is used as a reserved register for the base pointer.

This patch is adapted from @qcolombet patch for cmpxchg at r263325.

This fixes PR43528.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D73475

Files:
  llvm/lib/Target/X86/X86ExpandPseudo.cpp
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/lib/Target/X86/X86ISelLowering.h
  llvm/lib/Target/X86/X86InstrCompiler.td
  llvm/lib/Target/X86/X86InstrInfo.td
  llvm/test/CodeGen/X86/base-pointer-and-mwaitx.ll

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