[all-commits] [llvm/llvm-project] 878bba: [win][x64] Windows x64 unwind v3: Update epilog in...

[Daniel Paoliello via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 878bbacfb0e6ced7c0313d5f7c097d7c94a1c4da
      https://github.com/llvm/llvm-project/commit/878bbacfb0e6ced7c0313d5f7c097d7c94a1c4da
  Author: Daniel Paoliello <danpao at microsoft.com>
  Date:   2026-06-12 (Fri, 12 Jun 2026)

  Changed paths:
    M llvm/lib/MC/MCWin64EH.cpp
    M llvm/lib/Support/Win64EH.cpp
    M llvm/test/MC/COFF/seh-unwindv3-inheritance.s
    M llvm/test/tools/llvm-objdump/COFF/win64-unwindv3-multi-epilog.yaml
    M llvm/test/tools/llvm-readobj/COFF/unwind-x86_64-v3-multi-epilog.yaml
    M llvm/tools/llvm-objdump/COFFDump.cpp
    M llvm/tools/llvm-readobj/Win64EHDumper.cpp

  Log Message:
  -----------
  [win][x64] Windows x64 unwind v3: Update epilog inheritance per spec clarification (#202778)

The Windows x64 unwind v3 spec was clarified
(MicrosoftDocs/cpp-docs#5936) to state that an EPILOG_INFO_V3 record
with `NumberOfOps == 0` inherits its effective fields from the first
*preceding* descriptor with `NumberOfOps != 0` (the "base"), not the
immediately preceding one. Additionally, Flags bits 0 and 1 are no
longer inherited; the producer must replicate them so they match the
base descriptor.

- Encoder (MCWin64EH.cpp): compare each epilog against the tracked base
descriptor, and emit EPILOG_INFO_LARGE in inherited descriptors' own
flags byte.
- Decoder (Win64EH.cpp): track the base index and inherit from it; keep
the record's own flags byte instead of copying the previous record's.
- Dumpers (llvm-readobj, llvm-objdump): reword "previous epilog" to
"base epilog".
- Tests: update multi-epilog expectations and add a LARGE
inherited-epilog case to seh-unwindv3-inheritance.s.



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