diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h index 417fe040d19..a721e54dc02 100644 --- a/include/llvm/MC/MCContext.h +++ b/include/llvm/MC/MCContext.h @@ -138,10 +138,15 @@ namespace llvm { SectionKind K) { return getMachOSection(Segment, Section, TypeAndAttributes, 0, K); } - + + const MCSectionELF *getELFSection(StringRef Section, unsigned Type, + unsigned Flags, SectionKind Kind); + const MCSectionELF *getELFSection(StringRef Section, unsigned Type, unsigned Flags, SectionKind Kind, - unsigned EntrySize = 0); + unsigned EntrySize, StringRef Group); + + const MCSectionELF *CreateELFGroupSection(); const MCSection *getCOFFSection(StringRef Section, unsigned Characteristics, int Selection, SectionKind Kind); diff --git a/include/llvm/MC/MCSectionELF.h b/include/llvm/MC/MCSectionELF.h index bf07b99b21a..5af538557e5 100644 --- a/include/llvm/MC/MCSectionELF.h +++ b/include/llvm/MC/MCSectionELF.h @@ -18,6 +18,8 @@ namespace llvm { +class MCSymbol; + /// MCSectionELF - This represents a section on linux, lots of unix variants /// and some bare metal systems. class MCSectionELF : public MCSection { @@ -37,12 +39,14 @@ class MCSectionELF : public MCSection { /// section does not contain fixed-sized entries 'EntrySize' will be 0. unsigned EntrySize; + const MCSymbol *Group; + private: friend class MCContext; MCSectionELF(StringRef Section, unsigned type, unsigned flags, - SectionKind K, unsigned entrySize) + SectionKind K, unsigned entrySize, const MCSymbol *group) : MCSection(SV_ELF, K), SectionName(Section), Type(type), Flags(flags), - EntrySize(entrySize) {} + EntrySize(entrySize), Group(group) {} ~MCSectionELF(); public: @@ -179,6 +183,7 @@ public: unsigned getType() const { return Type; } unsigned getFlags() const { return Flags; } unsigned getEntrySize() const { return EntrySize; } + const MCSymbol *getGroup() const { return Group; } void PrintSwitchToSection(const MCAsmInfo &MAI, raw_ostream &OS) const; diff --git a/include/llvm/Support/ELF.h b/include/llvm/Support/ELF.h index 3c8b7299755..c6304aa34bb 100644 --- a/include/llvm/Support/ELF.h +++ b/include/llvm/Support/ELF.h @@ -348,6 +348,13 @@ enum { SHF_MASKPROC = 0xf0000000 // Bits indicating processor-specific flags. }; +// Section Group Flags +enum { + GRP_COMDAT = 0x1, + GRP_MASKOS = 0x0ff00000, + GRP_MASKPROC = 0xf0000000 +}; + // Symbol table entries for ELF32. struct Elf32_Sym { Elf32_Word st_name; // Symbol name (index into string table) diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp index 93ea77a0e1c..f8caee9882f 100644 --- a/lib/MC/ELFObjectWriter.cpp +++ b/lib/MC/ELFObjectWriter.cpp @@ -326,6 +326,11 @@ namespace { void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap); + // Map from a group section to the signature symbol + typedef DenseMap GroupMapTy; + void CreateGroupSections(MCAssembler &Asm, MCAsmLayout &Layout, + GroupMapTy &GroupMap); + void ExecutePostLayoutBinding(MCAssembler &Asm); void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags, @@ -344,6 +349,7 @@ namespace { void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout); void WriteSection(MCAssembler &Asm, const SectionIndexMapTy &SectionIndexMap, + uint32_t GroupSymbolIndex, uint64_t Offset, uint64_t Size, uint64_t Alignment, const MCSectionELF &Section); }; @@ -939,6 +945,17 @@ void ELFObjectWriterImpl::ComputeIndexMap(MCAssembler &Asm, ie = Asm.end(); it != ie; ++it) { const MCSectionELF &Section = static_cast(it->getSection()); + if (Section.getType() != ELF::SHT_GROUP) + continue; + SectionIndexMap[&Section] = Index++; + } + + for (MCAssembler::iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast(it->getSection()); + if (Section.getType() == ELF::SHT_GROUP) + continue; SectionIndexMap[&Section] = Index++; } } @@ -1062,7 +1079,7 @@ void ELFObjectWriterImpl::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout, RelaSection = Ctx.getELFSection(RelaSectionName, HasRelocationAddend ? ELF::SHT_RELA : ELF::SHT_REL, 0, SectionKind::getReadOnly(), - EntrySize); + EntrySize, ""); MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection); RelaSD.setAlignment(Is64Bit ? 8 : 4); @@ -1148,7 +1165,7 @@ void ELFObjectWriterImpl::CreateMetadataSections(MCAssembler &Asm, const MCSectionELF *SymtabSection = Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0, SectionKind::getReadOnly(), - EntrySize); + EntrySize, ""); MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection); SymtabSD.setAlignment(Is64Bit ? 8 : 4); SymbolTableIndex = Asm.size(); @@ -1158,7 +1175,7 @@ void ELFObjectWriterImpl::CreateMetadataSections(MCAssembler &Asm, if (NeedsSymtabShndx) { const MCSectionELF *SymtabShndxSection = Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0, - SectionKind::getReadOnly(), 4); + SectionKind::getReadOnly(), 4, ""); SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection); SymtabShndxSD->setAlignment(4); } @@ -1195,18 +1212,25 @@ void ELFObjectWriterImpl::CreateMetadataSections(MCAssembler &Asm, uint64_t Index = 1; F->getContents() += '\x00'; + StringMap SecStringMap; for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { const MCSectionELF &Section = static_cast(it->getSection()); // FIXME: We could merge suffixes like in .text and .rela.text. + StringRef Name = Section.getSectionName(); + if (SecStringMap.count(Name)) { + SectionStringTableIndex[&Section] = SecStringMap[Name]; + continue; + } // Remember the index into the string table so we can write it // into the sh_name field of the section header table. - SectionStringTableIndex[&it->getSection()] = Index; + SectionStringTableIndex[&Section] = Index; + SecStringMap[Name] = Index; - Index += Section.getSectionName().size() + 1; - F->getContents() += Section.getSectionName(); + Index += Name.size() + 1; + F->getContents() += Name; F->getContents() += '\x00'; } @@ -1247,8 +1271,59 @@ bool ELFObjectWriterImpl::IsFixupFullyResolved(const MCAssembler &Asm, return !SectionB && BaseSection == SectionA; } +void ELFObjectWriterImpl::CreateGroupSections(MCAssembler &Asm, + MCAsmLayout &Layout, + GroupMapTy &GroupMap) { + typedef DenseMap RevGroupMapTy; + // Build the groups + RevGroupMapTy Groups; + for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); + it != ie; ++it) { + const MCSectionELF &Section = + static_cast(it->getSection()); + if (!(Section.getFlags() & MCSectionELF::SHF_GROUP)) + continue; + + const MCSymbol *SignatureSymbol = Section.getGroup(); + Asm.getOrCreateSymbolData(*SignatureSymbol); + const MCSectionELF *&Group = Groups[SignatureSymbol]; + if (!Group) { + Group = Asm.getContext().CreateELFGroupSection(); + MCSectionData &Data = Asm.getOrCreateSectionData(*Group); + Data.setAlignment(4); + MCDataFragment *F = new MCDataFragment(&Data); + String32(*F, ELF::GRP_COMDAT); + } + GroupMap[Group] = SignatureSymbol; + } + + // Add sections to the groups + unsigned Index = 1; + unsigned NumGroups = Groups.size(); + for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); + it != ie; ++it, ++Index) { + const MCSectionELF &Section = + static_cast(it->getSection()); + if (!(Section.getFlags() & MCSectionELF::SHF_GROUP)) + continue; + const MCSectionELF *Group = Groups[Section.getGroup()]; + MCSectionData &Data = Asm.getOrCreateSectionData(*Group); + // FIXME: we could use the previous fragment + MCDataFragment *F = new MCDataFragment(&Data); + String32(*F, NumGroups + Index); + } + + for (RevGroupMapTy::const_iterator i = Groups.begin(), e = Groups.end(); + i != e; ++i) { + const MCSectionELF *Group = i->second; + MCSectionData &Data = Asm.getOrCreateSectionData(*Group); + Asm.AddSectionToTheEnd(*Writer, Data, Layout); + } +} + void ELFObjectWriterImpl::WriteSection(MCAssembler &Asm, const SectionIndexMapTy &SectionIndexMap, + uint32_t GroupSymbolIndex, uint64_t Offset, uint64_t Size, uint64_t Alignment, const MCSectionELF &Section) { @@ -1300,6 +1375,12 @@ void ELFObjectWriterImpl::WriteSection(MCAssembler &Asm, // Nothing to do. break; + case ELF::SHT_GROUP: { + sh_link = SymbolTableIndex; + sh_info = GroupSymbolIndex; + break; + } + default: assert(0 && "FIXME: sh_type value not supported!"); break; @@ -1312,6 +1393,10 @@ void ELFObjectWriterImpl::WriteSection(MCAssembler &Asm, void ELFObjectWriterImpl::WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) { + + GroupMapTy GroupMap; + CreateGroupSections(Asm, const_cast(Layout), GroupMap); + SectionIndexMapTy SectionIndexMap; ComputeIndexMap(Asm, SectionIndexMap); @@ -1332,9 +1417,18 @@ void ELFObjectWriterImpl::WriteObject(MCAssembler &Asm, uint64_t HeaderSize = Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr); uint64_t FileOff = HeaderSize; - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { - const MCSectionData &SD = *it; + std::vector Sections; + Sections.resize(NumSections); + + for (SectionIndexMapTy::const_iterator i= + SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) { + const std::pair &p = *i; + Sections[p.second] = p.first; + } + + for (unsigned i = 1; i < NumSections; ++i) { + const MCSectionELF &Section = *Sections[i]; + const MCSectionData &SD = Asm.getOrCreateSectionData(Section); FileOff = RoundUpToAlignment(FileOff, SD.getAlignment()); @@ -1354,20 +1448,20 @@ void ELFObjectWriterImpl::WriteObject(MCAssembler &Asm, // ... then all of the sections ... DenseMap SectionOffsetMap; - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { - const MCSectionData &SD = *it; + for (unsigned i = 1; i < NumSections; ++i) { + const MCSectionELF &Section = *Sections[i]; + const MCSectionData &SD = Asm.getOrCreateSectionData(Section); uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment()); WriteZeros(Padding); FileOff += Padding; // Remember the offset into the file for this section. - SectionOffsetMap[&it->getSection()] = FileOff; + SectionOffsetMap[&Section] = FileOff; FileOff += Layout.getSectionFileSize(&SD); - Asm.WriteSectionData(it, Layout, Writer); + Asm.WriteSectionData(&SD, Layout, Writer); } uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment); @@ -1384,14 +1478,17 @@ void ELFObjectWriterImpl::WriteObject(MCAssembler &Asm, ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0; WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0); - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { - const MCSectionData &SD = *it; - const MCSectionELF &Section = - static_cast(SD.getSection()); + for (unsigned i = 1; i < NumSections; ++i) { + const MCSectionELF &Section = *Sections[i]; + const MCSectionData &SD = Asm.getOrCreateSectionData(Section); + uint32_t GroupSymbolIndex; + if (Section.getType() != ELF::SHT_GROUP) + GroupSymbolIndex = 0; + else + GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, GroupMap[&Section]); - WriteSection(Asm, SectionIndexMap, SectionOffsetMap[&Section], - Layout.getSectionSize(&SD), + WriteSection(Asm, SectionIndexMap, GroupSymbolIndex, + SectionOffsetMap[&Section], Layout.getSectionSize(&SD), SD.getAlignment(), Section); } } diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp index bafa10a174a..311f383a3aa 100644 --- a/lib/MC/MCContext.cpp +++ b/lib/MC/MCContext.cpp @@ -150,7 +150,13 @@ getMachOSection(StringRef Segment, StringRef Section, const MCSectionELF *MCContext:: getELFSection(StringRef Section, unsigned Type, unsigned Flags, - SectionKind Kind, unsigned EntrySize) { + SectionKind Kind) { + return getELFSection(Section, Type, Flags, Kind, 0, ""); +} + +const MCSectionELF *MCContext:: +getELFSection(StringRef Section, unsigned Type, unsigned Flags, + SectionKind Kind, unsigned EntrySize, StringRef Group) { if (ELFUniquingMap == 0) ELFUniquingMap = new ELFUniqueMapTy(); ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap; @@ -163,12 +169,24 @@ getELFSection(StringRef Section, unsigned Type, unsigned Flags, if (!EntrySize) { EntrySize = MCSectionELF::DetermineEntrySize(Kind); } + + MCSymbol *GroupSym = NULL; + if (!Group.empty()) + GroupSym = GetOrCreateSymbol(Group); + MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags, - Kind, EntrySize); + Kind, EntrySize, GroupSym); Entry.setValue(Result); return Result; } +const MCSectionELF *MCContext::CreateELFGroupSection() { + MCSectionELF *Result = + new (*this) MCSectionELF(".group", MCSectionELF::SHT_GROUP, 0, + SectionKind::getReadOnly(), 4, NULL); + return Result; +} + const MCSection *MCContext::getCOFFSection(StringRef Section, unsigned Characteristics, int Selection, diff --git a/lib/MC/MCParser/ELFAsmParser.cpp b/lib/MC/MCParser/ELFAsmParser.cpp index 75eee3d4420..278f146ad67 100644 --- a/lib/MC/MCParser/ELFAsmParser.cpp +++ b/lib/MC/MCParser/ELFAsmParser.cpp @@ -203,6 +203,7 @@ bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) { StringRef FlagsStr; StringRef TypeName; int64_t Size = 0; + StringRef GroupName; if (getLexer().is(AsmToken::Comma)) { Lex(); @@ -249,7 +250,6 @@ bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) { if (getLexer().isNot(AsmToken::Comma)) return TokError("expected group name"); Lex(); - StringRef GroupName; if (getParser().ParseIdentifier(GroupName)) return true; if (getLexer().is(AsmToken::Comma)) { @@ -257,8 +257,8 @@ bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) { StringRef Linkage; if (getParser().ParseIdentifier(Linkage)) return true; - if (Linkage != "comdat" && Linkage != ".gnu.linkonce") - return TokError("Linkage must be 'comdat' or '.gnu.linkonce'"); + if (Linkage != "comdat") + return TokError("Linkage must be 'comdat'"); } } } @@ -306,6 +306,7 @@ bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) { Flags |= MCSectionELF::XCORE_SHF_DP_SECTION; break; case 'G': + Flags |= MCSectionELF::SHF_GROUP; break; default: return TokError("unknown flag"); @@ -331,7 +332,8 @@ bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) { ? SectionKind::getText() : SectionKind::getDataRel(); getStreamer().SwitchSection(getContext().getELFSection(SectionName, Type, - Flags, Kind, Size)); + Flags, Kind, Size, + GroupName)); return false; } @@ -405,7 +407,7 @@ bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) { MCSectionELF::SHF_MERGE | MCSectionELF::SHF_STRINGS, SectionKind::getReadOnly(), - 1); + 1, ""); static bool First = true; diff --git a/test/MC/ELF/comdat.s b/test/MC/ELF/comdat.s new file mode 100644 index 00000000000..ba4c9c7abbf --- /dev/null +++ b/test/MC/ELF/comdat.s @@ -0,0 +1,39 @@ +// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump | FileCheck %s + +// Test that we produce the two group sections and that they are a the beginning +// of the file. + +// CHECK: # Section 0x00000001 +// CHECK-NEXT: (('sh_name', 0x00000021) # '.group' +// CHECK-NEXT: ('sh_type', 0x00000011) +// CHECK-NEXT: ('sh_flags', 0x00000000) +// CHECK-NEXT: ('sh_addr', 0x00000000) +// CHECK-NEXT: ('sh_offset', 0x00000040) +// CHECK-NEXT: ('sh_size', 0x0000000c) +// CHECK-NEXT: ('sh_link', 0x0000000a) +// CHECK-NEXT: ('sh_info', 0x00000001) +// CHECK-NEXT: ('sh_addralign', 0x00000004) +// CHECK-NEXT: ('sh_entsize', 0x00000004) +// CHECK-NEXT: ), +// CHECK-NEXT: # Section 0x00000002 +// CHECK-NEXT: (('sh_name', 0x00000021) # '.group' +// CHECK-NEXT: ('sh_type', 0x00000011) +// CHECK-NEXT: ('sh_flags', 0x00000000) +// CHECK-NEXT: ('sh_addr', 0x00000000) +// CHECK-NEXT: ('sh_offset', 0x0000004c) +// CHECK-NEXT: ('sh_size', 0x00000008) +// CHECK-NEXT: ('sh_link', 0x0000000a) +// CHECK-NEXT: ('sh_info', 0x00000002) +// CHECK-NEXT: ('sh_addralign', 0x00000004) +// CHECK-NEXT: ('sh_entsize', 0x00000004) + + .section .foo,"axG",@progbits,g1,comdat +g1: + nop + + .section .bar,"axG",@progbits,g1,comdat + nop + + .section .zed,"axG",@progbits,g2,comdat +g2: + nop diff --git a/test/MC/ELF/section.s b/test/MC/ELF/section.s index 74fd38eaf88..9e9129df8f3 100644 --- a/test/MC/ELF/section.s +++ b/test/MC/ELF/section.s @@ -20,31 +20,31 @@ // CHECK-NEXT: ('sh_type', 0x00000001) // CHECK-NEXT: ('sh_flags', 0x00000006) // CHECK-NEXT: ('sh_addr', 0x00000000) -// CHECK-NEXT: ('sh_offset', 0x00000040) +// CHECK-NEXT: ('sh_offset', 0x00000050) // CHECK-NEXT: ('sh_size', 0x00000000) // CHECK-NEXT: ('sh_link', 0x00000000) // CHECK-NEXT: ('sh_info', 0x00000000) // CHECK-NEXT: ('sh_addralign', 0x00000001) // CHECK-NEXT: ('sh_entsize', 0x00000000) // CHECK-NEXT: ), -// CHECK-NEXT: # Section 0x00000008 +// CHECK-NEXT: # Section 0x0000000a // CHECK-NEXT: (('sh_name', 0x0000003e) # '.fini' // CHECK-NEXT: ('sh_type', 0x00000001) // CHECK-NEXT: ('sh_flags', 0x00000006) // CHECK-NEXT: ('sh_addr', 0x00000000) -// CHECK-NEXT: ('sh_offset', 0x00000040) +// CHECK-NEXT: ('sh_offset', 0x00000050) // CHECK-NEXT: ('sh_size', 0x00000000) // CHECK-NEXT: ('sh_link', 0x00000000) // CHECK-NEXT: ('sh_info', 0x00000000) // CHECK-NEXT: ('sh_addralign', 0x00000001) // CHECK-NEXT: ('sh_entsize', 0x00000000) // CHECK-NEXT: ), -// CHECK-NEXT: # Section 0x00000009 +// CHECK-NEXT: # Section 0x0000000b // CHECK-NEXT: (('sh_name', 0x00000044) # '.rodata' // CHECK-NEXT: ('sh_type', 0x00000001) // CHECK-NEXT: ('sh_flags', 0x00000002) // CHECK-NEXT: ('sh_addr', 0x00000000) -// CHECK-NEXT: ('sh_offset', 0x00000040) +// CHECK-NEXT: ('sh_offset', 0x00000050) // CHECK-NEXT: ('sh_size', 0x00000000) // CHECK-NEXT: ('sh_link', 0x00000000) // CHECK-NEXT: ('sh_info', 0x00000000) @@ -53,5 +53,7 @@ // CHECK-NEXT: ), // Test that we can parse these +foo: +bar: .section .text.foo,"axG",@progbits,foo,comdat -.section .text.bar,"axMG",@progbits,42,bar,.gnu.linkonce +.section .text.bar,"axMG",@progbits,42,bar,comdat