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[ELF] Never allocate content to weak symbols as they may be merged away. 

This is done by creating a new non-weak anonymous symbol and creating
an atom with content for that symbol. This is added after the weak symbol
so that they have the same address.

llvm-svn: 172553
This commit is contained in:
Michael J. Spencer 2013-01-15 21:13:02 +00:00
parent 842885e06e
commit 8b3898af26
2 changed files with 22 additions and 4 deletions
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18
lld/lib/ReaderWriter/ELF/ReaderELF.cpp
View File

@ -215,6 +215,22 @@ public:
: (*(si + 1))->st_value - (*si)->st_value; : (*(si + 1))->st_value - (*si)->st_value;
} }
// Don't allocate content to a weak symbol, as they may be merged away.
// Create an anonymous atom to hold the data.
ELFDefinedAtom<ELFT> *anonAtom = nullptr;
if ((*si)->getBinding() == llvm::ELF::STB_WEAK && contentSize != 0) {
// Create a new non-weak ELF symbol.
auto sym = new (_readerStorage.Allocate<Elf_Sym>()) Elf_Sym;
*sym = **si;
sym->setBinding(llvm::ELF::STB_GLOBAL);
anonAtom = createDefinedAtomAndAssignRelocations(
"", sectionName, sym, i.first,
ArrayRef<uint8_t>(
(uint8_t *)sectionContents.data() + (*si)->st_value, contentSize));
contentSize = 0;
}
ArrayRef<uint8_t> symbolData = ArrayRef<uint8_t>( ArrayRef<uint8_t> symbolData = ArrayRef<uint8_t>(
(uint8_t *)sectionContents.data() + (*si)->st_value, contentSize); (uint8_t *)sectionContents.data() + (*si)->st_value, contentSize);
@ -223,6 +239,8 @@ public:
_definedAtoms._atoms.push_back(newAtom); _definedAtoms._atoms.push_back(newAtom);
_symbolToAtomMapping.insert(std::make_pair((*si), newAtom)); _symbolToAtomMapping.insert(std::make_pair((*si), newAtom));
if (anonAtom)
_definedAtoms._atoms.push_back(anonAtom);
} }
} }

8
lld/test/elf/check.objtxt
View File

@ -13,9 +13,9 @@ ELF-i386: 00, E8, FC, FF, FF, FF, C9, C3 ]
ELF-i386: - name: weak_func ELF-i386: - name: weak_func
ELF-i386: scope: global ELF-i386: scope: global
ELF-i386: content: [ 55, 89, E5, 83, EC, 18, C7, 04, 24, 0E, 00, 00,
ELF-i386: 00, E8, FC, FF, FF, FF, C9, C3 ]
ELF-i386: merge: as-weak ELF-i386: merge: as-weak
ELF-i386: content: [ 55, 89, E5, 83, EC, 18, C7, 04, 24, 0E, 00, 00,
ELF-i386: 00, E8, FC, FF, FF, FF, C9, C3 ]
ELF-i386: - name: hidden_func ELF-i386: - name: hidden_func
ELF-i386: scope: hidden ELF-i386: scope: hidden
@ -65,9 +65,9 @@ ELF-hexagon: 00, C0, 00, 5A, 1E, C0, 1E, 96 ]
ELF-hexagon: - name: weak_func ELF-hexagon: - name: weak_func
ELF-hexagon: scope: global ELF-hexagon: scope: global
ELF-hexagon: content: [ 00, C0, 9D, A0, 00, 40, 00, 00, 00, C0, 00, 78,
ELF-hexagon: 00, C0, 00, 5A, 1E, C0, 1E, 96 ]
ELF-hexagon: merge: as-weak ELF-hexagon: merge: as-weak
ELF-hexagon: content: [ 00, C0, 9D, A0, 00, 40, 00, 00, 00, C0, 00, 78,
ELF-hexagon: 00, C0, 00, 5A, 1E, C0, 1E, 96 ]
ELF-hexagon: - name: hidden_func ELF-hexagon: - name: hidden_func
ELF-hexagon: scope: hidden ELF-hexagon: scope: hidden