Note: This revision is very similar to D62296.
In D75756, we need getDynamicSymbolIterators() to skip first NULL symbol in .dynsym. And I believe it might be worth pointing this out in a separate patch to gather you experts' opinions.
I have checked that current code base will not be affected by this change.
dynamic_symbol_begin()
|- dynamic_symbol_end(): Ok
`- getDynamicSymbolIterators()
|- addDynamicElfSymbols(): llvm/tools/llvm-objdump/llvm-objdump.cpp, Line 934
| Ok, NULL symbol will be omitted by Line 945-947
| StringRef Name = unwrapOrError(Symbol.getName(), Obj->getName());
| if (Name.empty()) continue;
|- dumpSymbolNameFromObject(): llvm/tools/llvm-nm/llvm-nm.cpp, Line 1192
| There's no test for dumping dynamic debugging symbol. This patch helps improve llvm-nm behavior. (we should add test for this later)
`- computeSymbolSizes(): llvm/lib/Object/SymbolSize.cpp, Line 52
|- OProfileJITEventListener::notifyObjectLoaded(): llvm/lib/ExecutionEngine/OProfileJIT/OProfileJITEventListener.cpp, Line 92
| Ok, NULL symbol will be omitted by Line 94-95
| if (!Sym.getType() || *Sym.getType() != SF_Function) continue;
|- IntelJITEventListener::notifyObjectLoaded(): llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp, Line 98
| Ok, NULL symbol will be omitted by Line 124-126 (same as previous one)
|- PerfJITEventListener::notifyObjectLoaded(): llvm/lib/ExecutionEngine/PerfJITEvents/PerfJITEventListener.cpp, Line 244
| Ok, NULL symbol will be omitted by Line 254-256, (same as previous one)
|- SymbolizableObjectFile::create(): llvm/lib/DebugInfo/Symbolize/SymbolizableObjectFile.cpp, Line 73
| Ok, NULL symbol will be omitted by Line 75
| res->addSymbol()
| In addSymbol(), Line 167-168
| if (!Sec || (Obj && Obj->section_end() == *Sec)) return std::error_code();
|- dumpCXXData(): llvm/tools/llvm-cxxdump/llvm-cxxdump.cpp, Line 189
| Ok, NULL symbol will be omitted by Line 199-202
| object::section_iterator SecI = *SecIOrErr;
| // Skip external symbols.
| if (SecI == Obj->section_end())
| continue;
`- printLineInfoForInput(): llvm/tools/llvm-rtdyld/llvm-rtdyld.cpp, Line 418
Ok, NULL symbol will be omitted by Line 430-477
if (Type == object::SymbolRef::ST_Function) {
...
}
Ok. So seems we are going to make this function to ignore the zero symbol.
Code on the left did not work with sh_size, you are adding the logic that uses it,
but what if sh_size is broken? Here, sh_size % sizeof(Elf_Sym) != 0
means we have a corrupted section isn't?
I'd suggest to isolate error handling. For now we can probably do something like:
// A comment saying we ignore this errors currently. if (!DotDynSymSec->sh_size || DotDynSymSec->sh_size % sizeof(Elf_Sym)) return dynamic_symbol_end(); // A comment about what we do. return {SymbolRef(toDRI(DotDynSymSec, 1), this};Do we have a test where this method is used when sh_size % sizeof(Elf_Sym) != 0?