[PATCH] D59553: llvm-symbolizer shows incorrect source line info if --gc-sections used
Alexey Lapshin via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 19 10:34:19 PDT 2019
avl created this revision.
avl added reviewers: ruiu, grimar, dblaikie, espindola.
Herald added subscribers: jdoerfert, MaskRay, arichardson, emaste.
Herald added a project: LLVM.
[DebugInfo][LLD] llvm-symbolizer shows incorrect source line info if --gc-sections used
for building binary.
This patch is a fix for https://bugs.llvm.org/show_bug.cgi?id=41124 .
When -Wl,--gc-sections is used : unreferenced .text sections could be removed,
but debug info related to these deleted sections left unchanged.
Address ranges for this not needed debug info could overlap with
address ranges for correct code. In such case symbolizer shows
line information incorrectly.
The real root of the problem is that irrelevant debug information left in the
binary. So the proper fix would be to delete that information completely. It would
probably be necessary to store debug information in COMDAT sections so that
linker would be able to remove not only unreferenced .text section but related debug
info also.
That fix implements workaround for the problem. It resolves relocations related to
debug info for deleted code so that they do not clash with real code. To achieve this
it set address ranges for such unneeded debug info out of module scope.
https://reviews.llvm.org/D59553
Files:
lld/ELF/InputSection.cpp
lld/ELF/OutputSections.cpp
lld/ELF/OutputSections.h
lld/ELF/Writer.cpp
lld/test/ELF/Inputs/main.s
lld/test/ELF/Inputs/not_used.s
lld/test/ELF/gc-sections-debuginfo.s
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