From cd0c3ea964473e05a4bbee1348507a77c9ac3707 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Martin=20Storsj=C3=B6?= Date: Wed, 26 Aug 2020 15:47:04 +0300 Subject: [PATCH] [LLD] [COFF] Check the aux section definition size for IMAGE_COMDAT_SELECT_SAME_SIZE Binutils generated sections seem to be padded to a multiple of 4 bytes, but the section definition contains the original, unpadded section length. This fixes statically linking clang-built object files with C++ typeinfo against libstdc++ built with GCC. --- lld/COFF/Chunks.cpp | 2 +- lld/COFF/Chunks.h | 4 +++ lld/COFF/InputFiles.cpp | 18 ++++++++---- lld/COFF/InputFiles.h | 7 +++-- lld/test/COFF/Inputs/comdat-binutils.yaml | 30 ++++++++++++++++++++ lld/test/COFF/Inputs/comdat-llvm.yaml | 30 ++++++++++++++++++++ lld/test/COFF/comdat-gcc-compatibility2.test | 15 ++++++++++ 7 files changed, 96 insertions(+), 10 deletions(-) create mode 100644 lld/test/COFF/Inputs/comdat-binutils.yaml create mode 100644 lld/test/COFF/Inputs/comdat-llvm.yaml create mode 100644 lld/test/COFF/comdat-gcc-compatibility2.test diff --git a/lld/COFF/Chunks.cpp b/lld/COFF/Chunks.cpp index b4b6b1cca03..3ff52c2a143 100644 --- a/lld/COFF/Chunks.cpp +++ b/lld/COFF/Chunks.cpp @@ -55,7 +55,7 @@ SectionChunk::SectionChunk(ObjFile *f, const coff_section *h) // SectionChunk is one of the most frequently allocated classes, so it is // important to keep it as compact as possible. As of this writing, the number // below is the size of this class on x64 platforms. -static_assert(sizeof(SectionChunk) <= 88, "SectionChunk grew unexpectedly"); +static_assert(sizeof(SectionChunk) <= 96, "SectionChunk grew unexpectedly"); static void add16(uint8_t *p, int16_t v) { write16le(p, read16le(p) + v); } static void add32(uint8_t *p, int32_t v) { write32le(p, read32le(p) + v); } diff --git a/lld/COFF/Chunks.h b/lld/COFF/Chunks.h index 0528143383c..f0555a4b39f 100644 --- a/lld/COFF/Chunks.h +++ b/lld/COFF/Chunks.h @@ -311,6 +311,10 @@ public: // Auxiliary Format 5: Section Definitions. Used for ICF. uint32_t checksum = 0; + // The section chunk length as defined in the section aux definition, + // if available. + uint32_t sectionDefLength = 0; + // Used by the garbage collector. bool live; diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp index 71af41da4d6..79c0086b01d 100644 --- a/lld/COFF/InputFiles.cpp +++ b/lld/COFF/InputFiles.cpp @@ -275,8 +275,10 @@ SectionChunk *ObjFile::readSection(uint32_t sectionNumber, if (sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE) return nullptr; auto *c = make(this, sec); - if (def) + if (def) { c->checksum = def->CheckSum; + c->sectionDefLength = def->Length; + } // CodeView sections are stored to a different vector because they are not // linked in the regular manner. @@ -476,8 +478,10 @@ Symbol *ObjFile::createUndefined(COFFSymbolRef sym) { return symtab->addUndefined(name, this, sym.isWeakExternal()); } -void ObjFile::handleComdatSelection(COFFSymbolRef sym, COMDATType &selection, - bool &prevailing, DefinedRegular *leader) { +void ObjFile::handleComdatSelection( + COFFSymbolRef sym, COMDATType &selection, bool &prevailing, + DefinedRegular *leader, + const llvm::object::coff_aux_section_definition *def) { if (prevailing) return; // There's already an existing comdat for this symbol: `Leader`. @@ -544,8 +548,10 @@ void ObjFile::handleComdatSelection(COFFSymbolRef sym, COMDATType &selection, break; case IMAGE_COMDAT_SELECT_SAME_SIZE: - if (leaderChunk->getSize() != getSection(sym)->SizeOfRawData) - symtab->reportDuplicate(leader, this); + if (leaderChunk->getSize() != getSection(sym)->SizeOfRawData) { + if (!config->mingw || leaderChunk->sectionDefLength != def->Length) + symtab->reportDuplicate(leader, this); + } break; case IMAGE_COMDAT_SELECT_EXACT_MATCH: { @@ -661,7 +667,7 @@ Optional ObjFile::createDefined( COMDATType selection = (COMDATType)def->Selection; if (leader->isCOMDAT) - handleComdatSelection(sym, selection, prevailing, leader); + handleComdatSelection(sym, selection, prevailing, leader, def); if (prevailing) { SectionChunk *c = readSection(sectionNumber, def, getName()); diff --git a/lld/COFF/InputFiles.h b/lld/COFF/InputFiles.h index 1e0b97a82be..0a5114b165f 100644 --- a/lld/COFF/InputFiles.h +++ b/lld/COFF/InputFiles.h @@ -255,9 +255,10 @@ private: // match the existing symbol and its selection. If either old or new // symbol have selection IMAGE_COMDAT_SELECT_LARGEST, Sym might replace // the existing leader. In that case, Prevailing is set to true. - void handleComdatSelection(COFFSymbolRef sym, - llvm::COFF::COMDATType &selection, - bool &prevailing, DefinedRegular *leader); + void + handleComdatSelection(COFFSymbolRef sym, llvm::COFF::COMDATType &selection, + bool &prevailing, DefinedRegular *leader, + const llvm::object::coff_aux_section_definition *def); llvm::Optional createDefined(COFFSymbolRef sym, diff --git a/lld/test/COFF/Inputs/comdat-binutils.yaml b/lld/test/COFF/Inputs/comdat-binutils.yaml new file mode 100644 index 00000000000..70fff87e1a4 --- /dev/null +++ b/lld/test/COFF/Inputs/comdat-binutils.yaml @@ -0,0 +1,30 @@ +--- !COFF +header: + Machine: IMAGE_FILE_MACHINE_AMD64 + Characteristics: [ IMAGE_FILE_RELOCS_STRIPPED, IMAGE_FILE_LINE_NUMS_STRIPPED ] +sections: + - Name: '.rdata$mysymbol' + Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ ] + Alignment: 16 + SectionData: 2A000000000000000000000000000000 +symbols: + - Name: '.rdata$mysymbol' + Value: 0 + SectionNumber: 1 + SimpleType: IMAGE_SYM_TYPE_NULL + ComplexType: IMAGE_SYM_DTYPE_NULL + StorageClass: IMAGE_SYM_CLASS_STATIC + SectionDefinition: + Length: 1 + NumberOfRelocations: 0 + NumberOfLinenumbers: 0 + CheckSum: 0 + Number: 0 + Selection: IMAGE_COMDAT_SELECT_SAME_SIZE + - Name: mysymbol + Value: 0 + SectionNumber: 1 + SimpleType: IMAGE_SYM_TYPE_NULL + ComplexType: IMAGE_SYM_DTYPE_NULL + StorageClass: IMAGE_SYM_CLASS_EXTERNAL +... diff --git a/lld/test/COFF/Inputs/comdat-llvm.yaml b/lld/test/COFF/Inputs/comdat-llvm.yaml new file mode 100644 index 00000000000..eef117a9233 --- /dev/null +++ b/lld/test/COFF/Inputs/comdat-llvm.yaml @@ -0,0 +1,30 @@ +--- !COFF +header: + Machine: IMAGE_FILE_MACHINE_AMD64 + Characteristics: [ ] +sections: + - Name: '.rdata$mysymbol' + Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ ] + Alignment: 1 + SectionData: 2A +symbols: + - Name: '.rdata$mysymbol' + Value: 0 + SectionNumber: 1 + SimpleType: IMAGE_SYM_TYPE_NULL + ComplexType: IMAGE_SYM_DTYPE_NULL + StorageClass: IMAGE_SYM_CLASS_STATIC + SectionDefinition: + Length: 1 + NumberOfRelocations: 0 + NumberOfLinenumbers: 0 + CheckSum: 3686517206 + Number: 1 + Selection: IMAGE_COMDAT_SELECT_SAME_SIZE + - Name: mysymbol + Value: 0 + SectionNumber: 1 + SimpleType: IMAGE_SYM_TYPE_NULL + ComplexType: IMAGE_SYM_DTYPE_NULL + StorageClass: IMAGE_SYM_CLASS_EXTERNAL +... diff --git a/lld/test/COFF/comdat-gcc-compatibility2.test b/lld/test/COFF/comdat-gcc-compatibility2.test new file mode 100644 index 00000000000..49386764636 --- /dev/null +++ b/lld/test/COFF/comdat-gcc-compatibility2.test @@ -0,0 +1,15 @@ +# RUN: yaml2obj %p/Inputs/comdat-llvm.yaml > %t.llvm.o +# RUN: yaml2obj %p/Inputs/comdat-binutils.yaml > %t.binutils.o +# RUN: lld-link -lldmingw -noentry -dll %t.llvm.o %t.binutils.o -out:%t.dll +# RUN: lld-link -lldmingw -noentry -dll %t.binutils.o %t.llvm.o -out:%t.dll +# RUN: not lld-link -noentry -dll %t.llvm.o %t.binutils.o -out:%t.dll +# RUN: not lld-link -noentry -dll %t.binutils.o %t.llvm.o -out:%t.dll + +# The test object files have been generated by assembling the following +# snippet using binutils and llvm. + +# .section .rdata$mysymbol, "dr" +# .linkonce same_size +# .globl mysymbol +#mysymbol: +# .byte 42 -- 2.17.1