[all-commits] [llvm/llvm-project] de3c84: [debuginfo][coro] Emit debug info labels for corou...

[Adrian Vogelsgesang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: de3c8410d87fa784bc97430ed759809cb942f894
      https://github.com/llvm/llvm-project/commit/de3c8410d87fa784bc97430ed759809cb942f894
  Author: Adrian Vogelsgesang <avogelsgesang at salesforce.com>
  Date:   2025-07-04 (Fri, 04 Jul 2025)

  Changed paths:
    M clang/docs/DebuggingCoroutines.rst
    M clang/lib/CodeGen/CGDebugInfo.cpp
    M clang/test/CodeGen/debug-label-inline.c
    M clang/test/CodeGen/debug-label.c
    M llvm/docs/LangRef.rst
    M llvm/include/llvm/BinaryFormat/Dwarf.def
    M llvm/include/llvm/IR/DIBuilder.h
    M llvm/include/llvm/IR/DebugInfoMetadata.h
    M llvm/lib/AsmParser/LLParser.cpp
    M llvm/lib/Bitcode/Reader/MetadataLoader.cpp
    M llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
    M llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
    M llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
    M llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
    M llvm/lib/IR/AsmWriter.cpp
    M llvm/lib/IR/DIBuilder.cpp
    M llvm/lib/IR/DebugInfo.cpp
    M llvm/lib/IR/DebugInfoMetadata.cpp
    M llvm/lib/IR/LLVMContextImpl.h
    M llvm/lib/Transforms/Coroutines/CoroFrame.cpp
    M llvm/lib/Transforms/Coroutines/CoroSplit.cpp
    M llvm/lib/Transforms/Utils/CodeExtractor.cpp
    M llvm/test/DebugInfo/Generic/debug-label.ll
    M llvm/test/Transforms/Coroutines/coro-debug-dbg.values.ll
    M llvm/test/Transforms/Coroutines/coro-debug.ll
    A llvm/test/Transforms/Coroutines/coro-split-dbg-labels.ll
    R llvm/test/Transforms/Coroutines/coro-split-no-lieftime.ll
    A llvm/test/Transforms/Coroutines/coro-split-no-lifetime.ll
    M llvm/unittests/IR/IRBuilderTest.cpp
    M mlir/lib/Target/LLVMIR/DebugTranslation.cpp

  Log Message:
  -----------
  [debuginfo][coro] Emit debug info labels for coroutine resume points (#141937)

RFC on discourse:
https://discourse.llvm.org/t/rfc-debug-info-for-coroutine-suspension-locations-take-2/86606

With this commit, we add `DILabel` debug infos to the resume points of a
coroutine. Those labels can be used by debugging scripts to figure out
the exact line and column at which a coroutine was suspended by looking
up current `__coro_index` value inside the coroutines frame, and then
searching for the corresponding label inside the coroutine's resume
function.

The DWARF information generated for such a label looks like:

```
0x00000f71:     DW_TAG_label
                  DW_AT_name    ("__coro_resume_1")
                  DW_AT_decl_file       ("generator-example.cpp")
                  DW_AT_decl_line       (5)
                  DW_AT_decl_column     (3)
                  DW_AT_artificial      (true)
                  DW_AT_LLVM_coro_suspend_idx   (0x01)
                  DW_AT_low_pc  (0x00000000000019be)
```

The labels can be mapped to their corresponding `__coro_idx` values
either via their naming convention `__coro_resume_<N>` or using the new
`DW_AT_LLVM_coro_suspend_idx` attribute. In gdb, those line numebrs can
be looked up using `info line -function my_coroutine -label
__coro_resume_1`. LLDB unfortunately does not understand DW_TAG_label
debug information, yet.

Given this is an artificial compiler-generated label, I did apply the
DW_AT_artificial tag to it. The DWARFv5 standard only allows that tag on
type and variable definitions, but this is a natural extension and was
also blessed in the RFC on discourse.

Also, this commit adds `DW_AT_decl_column` to labels, not only for
coroutines but also for normal C and C++ labels. While not strictly
necessary, I am doing so now because it would be harder to do so later
without breaking the binary LLVM-IR format

Drive-by fixes: While reading the existing test cases to understand how
to write my own test case, I did a couple of small typo fixes and
comment improvements



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