[all-commits] [llvm/llvm-project] fc6e97: [MC][X86] Avoid copying MCInst in emitInstrEnd (#9...

[aengelke via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: fc6e97cf2f28a9c7a73b97488ec6b90fc0d34a4a
      https://github.com/llvm/llvm-project/commit/fc6e97cf2f28a9c7a73b97488ec6b90fc0d34a4a
  Author: aengelke <engelke at in.tum.de>
  Date:   2024-06-11 (Tue, 11 Jun 2024)

  Changed paths:
    M llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp

  Log Message:
  -----------
  [MC][X86] Avoid copying MCInst in emitInstrEnd (#94947)

Copying an MCInst isn't cheap (copies all operands) and the whole
instruction is only used for the Intel erratum mitigation, which is off
by default. In all other cases, the opcode alone suffices.

This slightly pessimizes code that uses moves to segment registers --
but that's uncommon and not performance-sensitive anyway.

As a related change, also call canPadInst() only when the result is
actually used, which is typically only the case in emitInstrEnd.

This gives a minor performance improvement.



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