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cpp_my_benchmark_stripped.bin is the C++ benchmark binary with DWARF sections removed (strip --strip-debug) but .symtab/.dynsym intact, plus a .gnu_debuglink pointing to cpp_my_benchmark.debug. cpp_my_benchmark.debug contains the extracted DWARF sections (objcopy --only-keep-debug). Together they mimic the libc + libc6-dbg split where system libraries ship stripped and debug packages provide separate .debug files.
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Pull request overview
Adds support for resolving DWARF from separate debug info files referenced via .gnu_debuglink, improving symbolization for stripped binaries (e.g., distro-provided *-dbg packages).
Changes:
- Implement
.gnu_debuglink-based lookup (GDB-style search order) and fallback when DWARF is missing in the main binary. - Add a regression test covering stripped-binary + separate debug file resolution.
- Introduce new perf-map test artifacts and add
crc32fastdependency for CRC verification.
Reviewed changes
Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
src/executor/wall_time/perf/debug_info.rs |
Adds .gnu_debuglink lookup + fallback logic and a new test for stripped binaries. |
Cargo.toml |
Adds crc32fast dependency for debuglink CRC validation. |
Cargo.lock |
Records dependency graph update including crc32fast. |
testdata/perf_map/cpp_my_benchmark_stripped.bin |
New LFS-tracked stripped ELF fixture containing .gnu_debuglink. |
testdata/perf_map/cpp_my_benchmark.debug |
New LFS-tracked separate debug file fixture with DWARF sections. |
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GuillaumeLagrange
approved these changes
Apr 21, 2026
libc.so.6 and libc.so.6.debug are the stripped libc plus its separate debug file from Ubuntu 22.04 (jammy) glibc 2.35-0ubuntu3, amd64. Extracted from the official .deb packages: pool/main/g/glibc/libc6_2.35-0ubuntu3_amd64.deb pool/main/g/glibc/libc6-dbg_2.35-0ubuntu3_amd64.deb via `ar x` + `tar --zstd -xf data.tar.zst`. The debug file originally lives under /usr/lib/debug/.build-id/89/c3cb85...1969.debug; it is renamed to libc.so.6.debug in testdata/ for readability. Tests that need the .gnu_debuglink basename stage a tempdir copy with the expected name. Build-id: 89c3cb85f9e55046776471fed05ec441581d1969 These fixtures exercise the build-id and .gnu_debuglink resolution paths against a real-world stripped system library, complementing the synthetic cpp_my_benchmark pair.
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Stripped system libraries (e.g. libc.so.6) ship without DWARF and with only .dynsym. Installing debug packages like libc6-dbg drops a companion .debug file, but the runner had no way to find it — leaving "Unknown symbol" entries and missing file/line info in flamegraphs. Resolve debug files via two mechanisms: 1. Build-ID lookup at /usr/lib/debug/.build-id/XX/YYYYYY.debug, which is how Ubuntu/Debian debug packages actually install files. 2. .gnu_debuglink with the standard GDB search order (same dir, .debug/ subdir, /usr/lib/debug/<path>/) and CRC32 validation to avoid using stale debug files after binary upgrades. The resolved debug file is used both for DWARF (file/line lookup in ModuleDebugInfo) and for merging the full .symtab into ModuleSymbols.
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