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Revamp cg_llvm debuginfo handling to use the LLVM-C API #134001

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workingjubilee opened this issue Dec 7, 2024 · 1 comment
Open

Revamp cg_llvm debuginfo handling to use the LLVM-C API #134001

workingjubilee opened this issue Dec 7, 2024 · 1 comment
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A-debuginfo Area: Debugging information in compiled programs (DWARF, PDB, etc.) A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-cleanup Category: PRs that clean code up or issues documenting cleanup. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@workingjubilee
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We currently use C++ code for some of our debuginfo stuff with LLVM. We should port it to the C API, so we don't have to continue maintaining irksome C++ bindings. This is the primary header in question: https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm-c/DebugInfo.h
@workingjubilee workingjubilee added A-debuginfo Area: Debugging information in compiled programs (DWARF, PDB, etc.) A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-cleanup Category: PRs that clean code up or issues documenting cleanup. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Dec 7, 2024
@rustbot rustbot added the needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. label Dec 7, 2024
@workingjubilee workingjubilee changed the title Revamp LLVM debuginfo handling to use the LLVM-C API Revamp `cg_llv debuginfo handling to use the LLVM-C API Dec 7, 2024
@workingjubilee workingjubilee changed the title Revamp `cg_llv debuginfo handling to use the LLVM-C API Revamp cg_llvm debuginfo handling to use the LLVM-C API Dec 7, 2024
@workingjubilee workingjubilee mentioned this issue Dec 7, 2024
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@jieyouxu jieyouxu removed the needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. label Dec 7, 2024
@workingjubilee workingjubilee mentioned this issue Dec 7, 2024
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@Zalathar
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Zalathar commented Dec 7, 2024 •
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Incomplete list of places where the LLVM-C API appears to be inadequate:

  • LLVMDIBuilderCreateCompileUnit
    • We pass a DICompileUnit::DebugNameTableKind to the C++ constructor, but the C API unconditionally passes DICompileUnit::DebugNameTableKind::Default.
    • There doesn't appear to be a way to change this afterwards.
    • This has something to do with not emitting .debug_pubnames and .debug_pubtypes on DWARFv4 or lower.
  • LLVMDIBuilderCreateFile
    • Doesn't allow passing an optional checksum or optional source text.
  • LLVMDIBuilderCreateFunction
    • Only supports a subset of DISubprogram::DISPFlags.
  • LLVMDIBuilderCreateEnumerator
    • Does not allow specifying bit-width of the value; default width appears to be 64, which cannot hold 128-bit values.
    • Unclear whether this is important or not.
  • LLVMDIBuilderCreateEnumerationType
    • Does not allow specifying IsScoped; default value is false but we always pass true.

LLVM-C functions that require LLVM 19, so we can't use them yet:

  • LLVMDIBuilderInsertDeclareRecordAtEnd

Wrapper functions that call a C++ method with no equivalent in the C API:

  • LLVMRustDIBuilderCreateMethod
  • LLVMRustDIBuilderCreateVariantMemberType
  • LLVMRustDIBuilderCreateVariantPart
  • LLVMRustDIBuilderCreateTemplateTypeParameter
  • LLVMRustDICompositeTypeReplaceArrays
  • LLVMRustDILocationCloneWithBaseDiscriminator

Wrapper functions that do non-trivial things and don't map cleanly to a single C or C++ API function:

  • LLVMRustDIBuilderCreateStaticVariable
  • LLVMRustDIBuilderCreateVariable

Wrapper functions for getting various DWARF constants:

  • LLVMRustDIBuilderCreateOpDeref
  • LLVMRustDIBuilderCreateOpPlusUconst
  • LLVMRustDIBuilderCreateOpLLVMFragment

@Zalathar Zalathar mentioned this issue Dec 7, 2024
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bors added a commit to rust-lang-ci/rust that referenced this issue Dec 12, 2024
@bors
Auto merge of rust-lang#134009 - Zalathar:llvm-di, r=<try>
3e30f53 
cg_llvm: Replace most of our DIBuilder wrappers with LLVM-C API bindings

Many of our `LLVMRust` wrapper functions for building debug info can be replaced with their equivalents in the LLVM-C API.

This mostly implements rust-lang#134001, though it punts on some of the trickier cases noted at rust-lang#134001 (comment).

---

Marking as draft for now, because I want to give myself more time to review my own changes.

r? workingjubilee
@Zalathar Zalathar mentioned this issue Feb 1, 2025
Merged
jhpratt added a commit to jhpratt/rust that referenced this issue Feb 4, 2025
@jhpratt
Rollup merge of rust-lang#136375 - Zalathar:llvm-di-builder, r=workin…
5bb1bbb 
…gjubilee

cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 1)

Part of rust-lang#134001, follow-up to rust-lang#136326, extracted from rust-lang#134009.

This PR performs an arbitrary subset of the LLVM-C binding migrations from rust-lang#134009, which should make it less tedious to review. The remaining migrations can occur in one or more subsequent PRs.
fmease added a commit to fmease/rust that referenced this issue Feb 5, 2025
@fmease
Rollup merge of rust-lang#136375 - Zalathar:llvm-di-builder, r=workin…
75989e9 
…gjubilee

cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 1)

Part of rust-lang#134001, follow-up to rust-lang#136326, extracted from rust-lang#134009.

This PR performs an arbitrary subset of the LLVM-C binding migrations from rust-lang#134009, which should make it less tedious to review. The remaining migrations can occur in one or more subsequent PRs.
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Feb 5, 2025
@rust-timer
Unrolled build for rust-lang#136375
0efe609 
Rollup merge of rust-lang#136375 - Zalathar:llvm-di-builder, r=workingjubilee

cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 1)

Part of rust-lang#134001, follow-up to rust-lang#136326, extracted from rust-lang#134009.

This PR performs an arbitrary subset of the LLVM-C binding migrations from rust-lang#134009, which should make it less tedious to review. The remaining migrations can occur in one or more subsequent PRs.
@Zalathar Zalathar mentioned this issue Feb 6, 2025
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A-debuginfo Area: Debugging information in compiled programs (DWARF, PDB, etc.) A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-cleanup Category: PRs that clean code up or issues documenting cleanup. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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