symtab/dwarf-reader: allow hinting of main symbols for aliases
In case of aliased symbols, the "main symbol" cannot be deduced from
the symtab as this solely contains a name->addr mapping and aliases
are represented by multiple names resolving to the same address.
Therefore the main symbol can only be picked rather randomly and
unpredictable.
Unlike DWARF, which contains a single symbol entry for only the main
symbol. Hence we can (late) detect the main symbol. Exploiting that
property allows to correct the addr->symbol lookup in the symtab to
return the correct main symbol and it also allows to correct the aliased
symbols to maintain the correct main symbol.
This patch adds the `update_main_symbol` functionality to `elf_symbol`
to update the main symbol by name (ELF symbols need unique names) and
adds `update_main_symbol` to `symtab` that makes use of said new method.
When we discover a main symbol during DWARF reading, we instruct the
symtab to update the mapping.
This creates consistent representations across different builds of the
same binary with the same ABI by pinning down the main symbol to the
defined one. Knowing the main symbol also helps to keep the correct
dwarf information in the representation in the presence of symbol
suppressions. A later patch will address that.
Some test cases in tests/data need adjustment and they have all been
verified to be valid changes.
- main symbol changed for various elf symbols
- test-annotate/test15-pr18892.so.abi
- test-annotate/test19-pr19023-libtcmalloc_and_profiler.so.abi
- test-annotate/test3.so.abi
- test-read-dwarf/test15-pr18892.so.abi
- test-read-dwarf/test19-pr19023-libtcmalloc_and_profiler.so.abi
- test-read-dwarf/test3.so.abi
- test-read-dwarf/test3.so.hash.abi
- due to main symbol changes, the symbol diff needs to be corrected
- test-diff-dwarf/test12-report.txt
- test-diff-pkg/tbb-4.1-9.20130314.fc22.x86_64--tbb-4.3-3.20141204.fc23.x86_64-report-0.txt
- test-diff-pkg/tbb-4.1-9.20130314.fc22.x86_64--tbb-4.3-3.20141204.fc23.x86_64-report-1.txt
- the test scenario needed adjustments as the main symbol changed
- test-diff-suppr/test23-alias-filter-4.suppr
- test-diff-suppr/test23-alias-filter-report-0.txt
- test-diff-suppr/test23-alias-filter-report-2.txt
As usual, the complete changelog follows.
* include/abg-ir.h (elf_symbol::update_main_symbol): New method.
* include/abg-symtab-reader.h (symtab::update_main_symbol): New method.
* src/abg-dwarf-reader.cc
(build_var_decl): Hint symtab about main symbol discovered in DWARF.
(build_function_decl): Likewise.
* src/abg-ir.cc (elf_symbol::get_main_symbol): Lock the weak_ptr
on access in both overloads.
(update_main_symbol): New method to allow updating the main symbol.
* src/abg-symtab-reader.cc (symtab::update_main_symbol): New method.
* data/Makefile.am: Add new test data files.
* tests/data/test-annotate/test15-pr18892.so.abi: Updated test file.
* tests/data/test-annotate/test19-pr19023-libtcmalloc_and_profiler.so.abi: Likewise.
* tests/data/test-annotate/test2.so.abi: Likewise.
* tests/data/test-annotate/test3.so.abi: Likewise.
* tests/data/test-diff-dwarf/test12-report.txt: Likewise.
* tests/data/test-diff-dwarf/test42-PR21296-clanggcc-report0.txt: Likewise.
* tests/data/test-diff-pkg/tbb-4.1-9.20130314.fc22.x86_64--tbb-4.3-3.20141204.fc23.x86_64-report-0.txt: Likewise.
* tests/data/test-diff-pkg/tbb-4.1-9.20130314.fc22.x86_64--tbb-4.3-3.20141204.fc23.x86_64-report-1.txt: Likewise.
* tests/data/test-diff-suppr/test23-alias-filter-4.suppr: Likewise.
* tests/data/test-diff-suppr/test23-alias-filter-report-0.txt: Likewise.
* tests/data/test-diff-suppr/test23-alias-filter-report-2.txt: Likewise.
* tests/data/test-read-dwarf/PR22015-libboost_iostreams.so.abi: Likewise.
* tests/data/test-read-dwarf/PR22122-libftdc.so.abi: Likewise.
* tests/data/test-read-dwarf/test10-pr18818-gcc.so.abi: Likewise.
* tests/data/test-read-dwarf/test11-pr18828.so.abi: Likewise.
* tests/data/test-read-dwarf/test12-pr18844.so.abi: Likewise.
* tests/data/test-read-dwarf/test15-pr18892.so.abi: Likewise.
* tests/data/test-read-dwarf/test16-pr18904.so.abi: Likewise.
* tests/data/test-read-dwarf/test19-pr19023-libtcmalloc_and_profiler.so.abi: Likewise.
* tests/data/test-read-dwarf/test2.so.abi: Likewise.
* tests/data/test-read-dwarf/test2.so.hash.abi: Likewise.
* tests/data/test-read-dwarf/test22-pr19097-libstdc++.so.6.0.17.so.abi: Likewise.
* tests/data/test-read-dwarf/test3.so.abi: Likewise.
* tests/data/test-read-dwarf/test3.so.hash.abi: Likewise.
* tests/data/test-symtab/basic/aliases.c: New test source file.
* tests/data/test-symtab/basic/aliases.so: Likewise.
* tests/test-symtab.cc (Symtab::AliasedFunctionSymbols): New test case.
(Symtab::AliasedVariableSymbols): Likewise.
Reviewed-by: Giuliano Procida <gprocida@google.com>
Signed-off-by: Matthias Maennich <maennich@google.com>
Change-Id: If47f8fed98bb96a3ff0911c683d5a09c2997b9cd
38 files changed
