Addr2line enhance 4#4976
Open
TianlongLiang wants to merge 2 commits into
Open
Conversation
…able overlay
Refactor the wasm symbolicator to make its DWARF workaround explicit
and unconditional. addr2line.py runs one llvm-symbolizer -f -i call
per address, then overlays the outermost frame's function name from a
startup-built DWARF interval table.
The overlay exists because llvm-symbolizer returns the wrong outermost
function name on wasm targets for two independent, source-verified
reasons:
- Symbol-table override on the outermost frame (LLVM design, not a
bug). symbolizeInlinedCode in llvm/lib/DebugInfo/Symbolize/
SymbolizableObjectFile.cpp unconditionally rewrites the outermost
frame's FunctionName from getNameFromSymbolTable when
FunctionNameKind::LinkageName and UseSymbolTable are both set, which
is the default. Inline frames come from getInliningInfoForAddress
(a different code path) and are provably immune.
- AddrDieMap invariant violation from wasm-opt -Oz -g DCE ghosts.
LocationUpdater::getNewFuncStart in binaryen's src/wasm/wasm-debug.cpp
returns 0 as a tombstone when an old address doesn't map to a
surviving IR node, and updateDIE writes it into DW_AT_low_pc without
removing the DW_TAG_subprogram. LLVM's updateAddressDieMap in
DWARFUnit.cpp requires child ranges ⊆ parent ranges; these ghosts
break that invariant so the map's upper_bound − 1 lookup returns
an insertion-order-dependent DIE.
Both mechanisms produce the same "wrong outermost frame name" symptom
and both apply on any supported wasi-sdk, so the overlay runs on every
resolution. build_subprogram_intervals filters three DIE classes at
parse time: DW_AT_declaration=true (forward decls), low_pc == 0
(DWARF Code-section-relative zero is the function-count LEB, not a
real body — this is the DCE-ghost pattern), and high_pc <= low_pc
(degenerate ranges). The innermost covering DW_TAG_subprogram wins.
Also includes accumulated tool improvements:
- --mode flag {interp,aot,fast-interp} for different runtime offset
conventions (interp post-advance, aot at-instruction-start,
fast-interp's transformed in-memory bytecode)
- Inline frame annotation "(inlined into <next>)" for clarity
- llvm-symbolizer preferred over llvm-addr2line for column info
- Fallback for offset=0 (trap at function entry; frame_ip not captured)
- Last-resort function-index name fallback when DWARF lacks PC ranges
Full design rationale, source citations, and empirical truth table in
test-tools/addr2line/README.md.
New test suite at test-tools/addr2line/tests/ exercising addr2line.py against purpose-built C/C++ sources covering the interval-table overlay contract and the tool's other behaviors: - Baseline single-function resolution - Inline expansion (always_inline, 4-level deep chain) - Cross-TU LTO inlining (multi-file recursion + wasm-opt -Oz -g, which exercises both LLVM outermost-name failure modes) - Trap inside loop body (DWARF line-table edge case) - Multi-frame call stack - C++ symbol demangling - AOT mode offset math - fast-interp / --no-addr fallbacks - offset=0 fallback (trap at function entry) - Empty input - Skip-guard invariant on build_subprogram_intervals (test_build_subprogram_intervals_filters_invalid_dies): rejects DW_AT_declaration=true DIEs, low_pc == 0 (wasm-opt DCE ghosts), and high_pc <= low_pc entries at parse time. Layout: test-tools/addr2line/tests/ ├── README.md -- documentation ├── conftest.py -- pytest fixtures (sdk discovery, build, │ run_addr2line invocation, multi-sdk │ parametrization) ├── test_addr2line.py -- 12 test cases ├── pytest.ini -- marker definitions (slow, multi_sdk) ├── run_tests.sh -- thin pytest wrapper ├── apps/ -- 8 purpose-built C/C++ sources └── fixtures/ -- 3 plaintext call-stack inputs Sources under apps/ are NOT copied from samples/; they target specific edge cases independent of sample evolution. Multi-SDK mode (--multi-sdk) parametrizes build-based tests over every detected wasi-sdk under /opt to catch DWARF-encoding differences between clang versions. Depends on the addr2line.py refactor.
BenSunWhiteBoard
force-pushed
the
addr2line_enhance_4
branch
from
9a85a2d to
a7243fc
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
No description provided.