[PATCH] D75081: [CodeView] Align type records on 4-bytes when emitting PDBs

[Alexandre Ganea via Phabricator via llvm-commits]

aganea created this revision.
aganea added reviewers: rnk, zturner.
Herald added subscribers: llvm-commits, rupprecht, hiraditya.
Herald added a reviewer: jhenderson.
Herald added a project: LLVM.

When emitting PDBs, the `TypeStreamMerger` class is used to merge `.debug$T` records from the input .OBJ files into the output .PDB stream.
Records in .OBJs are not required to be aligned on 4-bytes, and "The Netwide Assembler 2.14" generates non-aligned records.

When compiling with `-DLLVM_ENABLE_ASSERTIONS=ON`, an assert was triggered in `MergingTypeTableBuilder` when non-ghash merging was used.
With ghash merging there was no assert.
As a result, LLD could potentially generate a non-aligned TPI stream.

We now align records on 4-bytes when record indices are remapped (in `TypeStreamMerger::remapIndices()`).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D75081

Files:
  llvm/include/llvm/DebugInfo/CodeView/GlobalTypeTableBuilder.h
  llvm/lib/DebugInfo/CodeView/TypeStreamMerger.cpp
  llvm/test/tools/llvm-readobj/COFF/codeview-merging-alignement.yaml

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