[PATCH] D71106: [MC] Delete MCCodePadder

Fangrui Song via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Dec 5 23:20:25 PST 2019


MaskRay created this revision.
MaskRay added reviewers: annita.zhang, craig.topper, fedor.sergeev, jyknight, skan, opaparo, reames.
Herald added subscribers: llvm-commits, atanasyan, jrtc27, hiraditya, mgorny, sdardis.
Herald added a project: LLVM.
MaskRay updated this revision to Diff 232499.
MaskRay added a comment.

Delete code that is only compiled in !NDEBUG builds


D34393 <https://reviews.llvm.org/D34393> added MCCodePadder as an infrastructure for padding code with
NOP instructions. It lacked tests and was not being worked on since
then.

Intel has now worked on an assembler patch to mitigate performance loss
after applying microcode update for the Jump Conditional Code Erratum.

https://www.intel.com/content/www/us/en/support/articles/000055650/processors.html

This new patch shares similarity with MCCodePadder, but has a concrete
use case in mind and is being actively developed. The infrastructure it
introduces can potentially be used for general performance improvement
via alignment. Delete the unused MCCodePadder so that people can develop
the new feature from a clean state.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D71106

Files:
  llvm/include/llvm/CodeGen/AsmPrinter.h
  llvm/include/llvm/MC/MCAsmBackend.h
  llvm/include/llvm/MC/MCAssembler.h
  llvm/include/llvm/MC/MCCodePadder.h
  llvm/include/llvm/MC/MCFragment.h
  llvm/include/llvm/MC/MCObjectStreamer.h
  llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
  llvm/lib/MC/CMakeLists.txt
  llvm/lib/MC/MCAsmBackend.cpp
  llvm/lib/MC/MCAssembler.cpp
  llvm/lib/MC/MCCodePadder.cpp
  llvm/lib/MC/MCFragment.cpp
  llvm/lib/MC/MCObjectStreamer.cpp
  llvm/lib/Target/Mips/MipsAsmPrinter.cpp
  llvm/lib/Target/X86/X86AsmPrinter.h
  llvm/utils/gn/secondary/llvm/lib/MC/BUILD.gn

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