[all-commits] [llvm/llvm-project] 28e147: MC: Remove bundle alignment mode

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 28e1473e8e523150914e8c7ea50b44fb0d2a8d65
      https://github.com/llvm/llvm-project/commit/28e1473e8e523150914e8c7ea50b44fb0d2a8d65
  Author: Fangrui Song <i at maskray.me>
  Date:   2025-07-15 (Tue, 15 Jul 2025)

  Changed paths:
    M llvm/include/llvm/MC/MCAssembler.h
    M llvm/include/llvm/MC/MCELFStreamer.h
    M llvm/include/llvm/MC/MCObjectStreamer.h
    M llvm/include/llvm/MC/MCSection.h
    M llvm/include/llvm/MC/MCStreamer.h
    M llvm/lib/MC/MCAsmStreamer.cpp
    M llvm/lib/MC/MCAssembler.cpp
    M llvm/lib/MC/MCELFStreamer.cpp
    M llvm/lib/MC/MCFragment.cpp
    M llvm/lib/MC/MCObjectStreamer.cpp
    M llvm/lib/MC/MCParser/AsmParser.cpp
    M llvm/lib/MC/MCSection.cpp
    M llvm/lib/MC/MCStreamer.cpp
    M llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
    R llvm/test/MC/ARM/AlignedBundling/group-bundle-arm.s
    R llvm/test/MC/ARM/AlignedBundling/illegal-subtarget-change.s
    R llvm/test/MC/ARM/AlignedBundling/lit.local.cfg
    R llvm/test/MC/ARM/AlignedBundling/pad-align-to-bundle-end.s
    R llvm/test/MC/ARM/AlignedBundling/subtarget-change.s
    M llvm/test/MC/AsmParser/AArch64/directive-parse-err.s
    R llvm/test/MC/X86/AlignedBundling/align-mode-argument-error.s
    R llvm/test/MC/X86/AlignedBundling/asm-printing-bundle-directives.s
    R llvm/test/MC/X86/AlignedBundling/autogen-inst-offset-align-to-end.s
    R llvm/test/MC/X86/AlignedBundling/autogen-inst-offset-padding.s
    R llvm/test/MC/X86/AlignedBundling/bundle-group-too-large-error.s
    R llvm/test/MC/X86/AlignedBundling/bundle-lock-option-error.s
    R llvm/test/MC/X86/AlignedBundling/bundle-subtarget-change-error.s
    R llvm/test/MC/X86/AlignedBundling/different-sections.s
    R llvm/test/MC/X86/AlignedBundling/labeloffset.s
    R llvm/test/MC/X86/AlignedBundling/lit.local.cfg
    R llvm/test/MC/X86/AlignedBundling/lock-without-bundle-mode-error.s
    R llvm/test/MC/X86/AlignedBundling/long-nop-pad.s
    R llvm/test/MC/X86/AlignedBundling/misaligned-bundle-group.s
    R llvm/test/MC/X86/AlignedBundling/misaligned-bundle.s
    R llvm/test/MC/X86/AlignedBundling/nesting.s
    R llvm/test/MC/X86/AlignedBundling/pad-align-to-bundle-end.s
    R llvm/test/MC/X86/AlignedBundling/pad-bundle-groups.s
    R llvm/test/MC/X86/AlignedBundling/relax-at-bundle-end.s
    R llvm/test/MC/X86/AlignedBundling/relax-in-bundle-group.s
    R llvm/test/MC/X86/AlignedBundling/section-alignment.s
    R llvm/test/MC/X86/AlignedBundling/single-inst-bundling.s
    R llvm/test/MC/X86/AlignedBundling/switch-section-locked-error.s
    R llvm/test/MC/X86/AlignedBundling/unlock-without-lock-error.s
    R llvm/test/MC/X86/align-branch-bundle.s

  Log Message:
  -----------
  MC: Remove bundle alignment mode

The being-removed PNaCl has a Software Fault Isolation mechanism, which
requires that certain instructions and groups of instructions do not
cross a bundle boundary. When `.bundle_align_mode` is in effect, each
instruction is placed in its own fragment, allowing flexible NOP
padding.

This feature has significantly complicated our refactoring of MCStreamer
and MCFragment, leading to considerable effort spent untangling
it (including flushPendingLabels (75006466296ed4b0f845cbbec4bf77c21de43b40),
MCAssembler iteration improvement, and recent MCFragment refactoring).

* Make MCObjectStreamer::emitInstToData non-virtual and delete
  MCELFStreamer::emitInstTodata
* Delete MCELFStreamer::emitValueImpl and emitValueToAlignment

Minor instructions:u decrease for both -O0 -g and -O3 builds
https://llvm-compile-time-tracker.com/compare.php?from=c06d3a7b728293cbc53ff91239d6cd87c0982ffb&to=9b078c7f228bc5b6cdbfe839f751c9407f8aec3e&stat=instructions:u

Pull Request: https://github.com/llvm/llvm-project/pull/148781



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