[all-commits] [llvm/llvm-project] 5b2c3a: [MCA][X86] Pretend To Have a Stack Engine (#153348)

[Aiden Grossman via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 5b2c3aac90450ecb78394f61afc7e9c5e955abc7
      https://github.com/llvm/llvm-project/commit/5b2c3aac90450ecb78394f61afc7e9c5e955abc7
  Author: Aiden Grossman <aidengrossman at google.com>
  Date:   2025-08-18 (Mon, 18 Aug 2025)

  Changed paths:
    M llvm/lib/Target/X86/MCA/X86CustomBehaviour.cpp
    M llvm/lib/Target/X86/MCA/X86CustomBehaviour.h
    A llvm/test/tools/llvm-mca/X86/stack-engine-pop.s
    A llvm/test/tools/llvm-mca/X86/stack-engine-push.s

  Log Message:
  -----------
  [MCA][X86] Pretend To Have a Stack Engine (#153348)

This patch removes RSP dependencies from push and pop instructions to
pretend that we have a stack engine. This does not model details like
sync uops that are relevant implementation details due to complexity.
This is just enabled on all X86 CPUs given LLVM does not have a
scheduling model for any X86 CPU that does not have a stack engine.

This fixes #152008.



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