rust-lang / rust-lang/rustc_codegen_gcc

Location generation in debuginfo treats mangled names as short names

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libgccjit
Dominant language
Rust
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Merged PRs (30d)
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Description

Problems

Currently, at least for GDB, demangling for variable names and function names are not supported by the debuginfo generated in cg_gcc.

Causes

For the short test program, https://github.com/rust-lang/rustc_codegen_gcc/blob/b5d61f1c9e2177f66f2c80c63ced76d8cc66d3db/example/std_example.rs, cg_gcc-generated debuginfo, as is dumped by abi-dumper:
ABI_gcc.txt
While in LLVM:
ABI_llvm.txt
Upon inspection, it's evident that the current debuginfo generation treats mangled names as short names in the DWARF file.

Potential Solutions

Add a new function to generate a Location from mangled names and change the internal representation of Location in gccjit to allow storage of names as demangled ones.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with debuginfo generation in cg_gcc and compare the ABI_gcc.txt and ABI_llvm.txt dumps for the example/std_example.rs program. Trace how gccjit represents Location names, then verify that generated DWARF distinguishes mangled names from short names and supports demangled variable and function names.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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