[all-commits] [llvm/llvm-project] 6c56a8: [clang][CodeGen] Generate follow-up metadata for l...

[Ryotaro Kasuga via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6c56a842b73cf2046b9ab8cf077890e11b758373
      https://github.com/llvm/llvm-project/commit/6c56a842b73cf2046b9ab8cf077890e11b758373
  Author: Ryotaro Kasuga <kasuga.ryotaro at fujitsu.com>
  Date:   2025-03-27 (Thu, 27 Mar 2025)

  Changed paths:
    M clang/lib/CodeGen/CGLoopInfo.cpp
    M clang/lib/CodeGen/CGLoopInfo.h
    M clang/test/CodeGenCXX/pragma-followup_inner.cpp
    M clang/test/CodeGenCXX/pragma-followup_outer.cpp
    M clang/test/CodeGenCXX/pragma-loop.cpp
    M llvm/test/Transforms/LoopVectorize/make-followup-loop-id.ll

  Log Message:
  -----------
  [clang][CodeGen] Generate follow-up metadata for loops in correct format  (#131985)

When pragma of loop transformations is specified, follow-up metadata for
loops is generated after each transformation. On the LLVM side,
follow-up metadata is expected to be a list of properties, such as the
following:

```
!followup = !{!"llvm.loop.vectorize.followup_all", !mp, !isvectorized}
!mp = !{!"llvm.loop.mustprogress"}
!isvectorized = !{"llvm.loop.isvectorized"}
```

However, on the clang side, the generated metadata contains an MDNode
that has those properties, as shown below:

```
!followup = !{!"llvm.loop.vectorize.followup_all", !loop_id}
!loop_id = distinct !{!loop_id, !mp, !isvectorized}
!mp = !{!"llvm.loop.mustprogress"}
!isvectorized = !{"llvm.loop.isvectorized"}
```
According to the
[LangRef](https://llvm.org/docs/TransformMetadata.html#transformation-metadata-structure),
the LLVM side is correct. Due to this inconsistency, follow-up metadata
was not interpreted correctly, e.g., only one transformation is applied
when multiple pragmas are used.

This patch fixes clang side to emit followup metadata in correct format.



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