diff options
| -rw-r--r-- | lld/lib/ReaderWriter/PECOFF/Atoms.h | 8 | ||||
| -rw-r--r-- | lld/lib/ReaderWriter/PECOFF/ReaderCOFF.cpp | 24 | ||||
| -rw-r--r-- | lld/test/pecoff/Inputs/common-symbol.obj.yaml (renamed from lld/test/pecoff/Inputs/bss-undef.obj.yaml) | 0 | ||||
| -rw-r--r-- | lld/test/pecoff/common-symbol.test (renamed from lld/test/pecoff/bss-undef.test) | 4 |
4 files changed, 25 insertions, 11 deletions
diff --git a/lld/lib/ReaderWriter/PECOFF/Atoms.h b/lld/lib/ReaderWriter/PECOFF/Atoms.h index 94904f8da74..8a61933a560 100644 --- a/lld/lib/ReaderWriter/PECOFF/Atoms.h +++ b/lld/lib/ReaderWriter/PECOFF/Atoms.h @@ -193,16 +193,18 @@ private: class COFFBSSAtom : public COFFDefinedFileAtom { public: COFFBSSAtom(const File &file, StringRef name, Scope scope, - ContentPermissions perms, uint32_t size, uint64_t ordinal) + ContentPermissions perms, Merge merge, uint32_t size, + uint64_t ordinal) : COFFDefinedFileAtom(file, name, "", scope, typeZeroFill, perms, ordinal), - _size(size) {} + _merge(merge), _size(size) {} - virtual Merge merge() const { return mergeNo; } + virtual Merge merge() const { return _merge; } virtual uint64_t size() const { return _size; } virtual ArrayRef<uint8_t> rawContent() const { return _contents; } private: + Merge _merge; uint32_t _size; std::vector<uint8_t> _contents; }; diff --git a/lld/lib/ReaderWriter/PECOFF/ReaderCOFF.cpp b/lld/lib/ReaderWriter/PECOFF/ReaderCOFF.cpp index 2e244440785..1e1f559e5f5 100644 --- a/lld/lib/ReaderWriter/PECOFF/ReaderCOFF.cpp +++ b/lld/lib/ReaderWriter/PECOFF/ReaderCOFF.cpp @@ -234,16 +234,28 @@ private: // Filter non-defined atoms, and group defined atoms by its section. SectionToSymbolsT definedSymbols; for (const coff_symbol *sym : symbols) { - // A symbol with section number 0 and non-zero value represents an - // uninitialized data. I don't understand why there are two ways to define - // an uninitialized data symbol (.bss and this way), but that's how COFF - // works. + // A symbol with section number 0 and non-zero value represents a common + // symbol. The MS COFF spec did not give a definition of what the common + // symbol is. We should probably follow ELF's definition shown below. + // + // - If one object file has a common symbol and another has a definition, + // the common symbol is treated as an undefined reference. + // - If there is no definition for a common symbol, the program linker + // acts as though it saw a definition initialized to zero of the + // appropriate size. + // - Two object files may have common symbols of + // different sizes, in which case the program linker will use the + // largest size. + // + // FIXME: We are currently treating the common symbol as a normal + // mergeable atom. Implement the above semantcis. if (sym->SectionNumber == llvm::COFF::IMAGE_SYM_UNDEFINED && sym->Value > 0) { StringRef name = _symbolName[sym]; uint32_t size = sym->Value; auto *atom = new (_alloc) COFFBSSAtom( - *this, name, getScope(sym), DefinedAtom::permRW_, size, 0); + *this, name, getScope(sym), DefinedAtom::permRW_, + DefinedAtom::mergeAsWeakAndAddressUsed, size, 0); result.push_back(atom); continue; } @@ -370,7 +382,7 @@ private: : si[1]->Value - sym->Value; auto *atom = new (_alloc) COFFBSSAtom( *this, _symbolName[sym], getScope(sym), getPermissions(section), - size, ++ordinal); + DefinedAtom::mergeAsWeakAndAddressUsed, size, ++ordinal); atoms.push_back(atom); _symbolAtom[sym] = atom; } diff --git a/lld/test/pecoff/Inputs/bss-undef.obj.yaml b/lld/test/pecoff/Inputs/common-symbol.obj.yaml index d10c8f7eefe..d10c8f7eefe 100644 --- a/lld/test/pecoff/Inputs/bss-undef.obj.yaml +++ b/lld/test/pecoff/Inputs/common-symbol.obj.yaml diff --git a/lld/test/pecoff/bss-undef.test b/lld/test/pecoff/common-symbol.test index e77940f2154..bd3c550662f 100644 --- a/lld/test/pecoff/bss-undef.test +++ b/lld/test/pecoff/common-symbol.test @@ -1,6 +1,6 @@ -# RUN: yaml2obj %p/Inputs/bss-undef.obj.yaml > %t.obj +# RUN: yaml2obj %p/Inputs/common-symbol.obj.yaml > %t.obj # -# RUN: lld -flavor link /out:%t /subsystem:console /force -- %t.obj \ +# RUN: lld -flavor link /out:%t /subsystem:console /force -- %t.obj %t.obj \ # RUN: && llvm-readobj -sections %t | FileCheck %s CHECK: Section { |
