[PATCH] D101970: [X86FixupLEAs] Transform the sequence LEA/SUB to SUB/SUB

[Guozhi Wei via Phabricator via llvm-commits]

Carrot created this revision.
Carrot added reviewers: craig.topper, spatel.
Herald added subscribers: mstorsjo, pengfei, hiraditya.
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This patch transforms the sequence

      lea (reg1, reg2), reg3
      sub reg3, reg4
  
  to two sub instructions
  
      sub reg1, reg4
      sub reg2, reg4

Similar optimization can also be applied to LEA/ADD sequence.
The modifications to TwoAddressInstructionPass is to ensure the operands of ADD instruction has expected order (the dest register of LEA should be src register of ADD).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D101970

Files:
  llvm/include/llvm/CodeGen/TargetInstrInfo.h
  llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
  llvm/lib/Target/X86/X86FixupLEAs.cpp
  llvm/lib/Target/X86/X86InstrInfo.cpp
  llvm/lib/Target/X86/X86InstrInfo.h
  llvm/test/CodeGen/X86/2009-03-23-MultiUseSched.ll
  llvm/test/CodeGen/X86/lea-opt2.ll
  llvm/test/CodeGen/X86/vp2intersect_multiple_pairs.ll

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