[ELF] Refactor EhOutputSection

[evgeny777]

Summary

Brush up few functions + fancier error messages

[ruiu]

LGTM

ELF/OutputSections.cpp

277

Use auto.

304

ditto

[thakis]

This breaks building on macOS:

[2814/2828] Linking CXX executable bin/lld
FAILED: bin/lld
: && /Applications/Xcode7.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -DLLVM_FORCE_HEAD_REVISION -fPIC -fvisibility-inlines-hidden -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Werror=date-time -std=c++11 -fcolor-diagnostics -O3 -isysroot /Applications/Xcode7.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names -Wl,-dead_strip tools/lld/tools/lld/CMakeFiles/lld.dir/lld.cpp.o -o bin/lld lib/liblldDriver.a lib/liblldCOFF.a lib/liblldELF.a lib/libLLVMSupport.a lib/liblldMachO.a lib/liblldReaderWriter.a lib/liblldYAML.a lib/libLLVMDebugInfoPDB.a lib/libLLVMLibDriver.a lib/liblldConfig.a lib/liblldCore.a lib/libLLVMOption.a lib/libLLVMAArch64CodeGen.a lib/libLLVMAArch64AsmParser.a lib/libLLVMAArch64Disassembler.a lib/libLLVMAArch64Desc.a lib/libLLVMAArch64AsmPrinter.a lib/libLLVMAArch64Info.a lib/libLLVMAArch64Utils.a lib/libLLVMAMDGPUCodeGen.a lib/libLLVMAMDGPUAsmParser.a lib/libLLVMAMDGPUDisassembler.a lib/libLLVMAMDGPUDesc.a lib/libLLVMAMDGPUAsmPrinter.a lib/libLLVMAMDGPUInfo.a lib/libLLVMAMDGPUUtils.a lib/libLLVMARMCodeGen.a lib/libLLVMARMAsmParser.a lib/libLLVMARMDisassembler.a lib/libLLVMARMDesc.a lib/libLLVMARMAsmPrinter.a lib/libLLVMARMInfo.a lib/libLLVMBPFCodeGen.a lib/libLLVMBPFDesc.a lib/libLLVMBPFAsmPrinter.a lib/libLLVMBPFDisassembler.a lib/libLLVMBPFInfo.a lib/libLLVMHexagonCodeGen.a lib/libLLVMHexagonAsmParser.a lib/libLLVMHexagonDisassembler.a lib/libLLVMHexagonDesc.a lib/libLLVMHexagonInfo.a lib/libLLVMLanaiCodeGen.a lib/libLLVMLanaiAsmParser.a lib/libLLVMLanaiDisassembler.a lib/libLLVMLanaiDesc.a lib/libLLVMLanaiInstPrinter.a lib/libLLVMLanaiInfo.a lib/libLLVMMipsCodeGen.a lib/libLLVMMipsAsmParser.a lib/libLLVMMipsDesc.a lib/libLLVMMipsAsmPrinter.a lib/libLLVMMipsDisassembler.a lib/libLLVMMipsInfo.a lib/libLLVMMSP430CodeGen.a lib/libLLVMMSP430Desc.a lib/libLLVMMSP430AsmPrinter.a lib/libLLVMMSP430Info.a lib/libLLVMNVPTXCodeGen.a lib/libLLVMNVPTXDesc.a lib/libLLVMNVPTXAsmPrinter.a lib/libLLVMNVPTXInfo.a lib/libLLVMPowerPCCodeGen.a lib/libLLVMPowerPCAsmParser.a lib/libLLVMPowerPCDesc.a lib/libLLVMPowerPCAsmPrinter.a lib/libLLVMPowerPCDisassembler.a lib/libLLVMPowerPCInfo.a lib/libLLVMRISCVCodeGen.a lib/libLLVMRISCVDesc.a lib/libLLVMRISCVInfo.a lib/libLLVMSparcCodeGen.a lib/libLLVMSparcAsmParser.a lib/libLLVMSparcDesc.a lib/libLLVMSparcAsmPrinter.a lib/libLLVMSparcDisassembler.a lib/libLLVMSparcInfo.a lib/libLLVMSystemZCodeGen.a lib/libLLVMSystemZAsmParser.a lib/libLLVMSystemZDisassembler.a lib/libLLVMSystemZDesc.a lib/libLLVMSystemZAsmPrinter.a lib/libLLVMSystemZInfo.a lib/libLLVMX86CodeGen.a lib/libLLVMGlobalISel.a lib/libLLVMX86AsmParser.a lib/libLLVMX86Desc.a lib/libLLVMX86AsmPrinter.a lib/libLLVMX86Utils.a lib/libLLVMX86Disassembler.a lib/libLLVMX86Info.a lib/libLLVMXCoreCodeGen.a lib/libLLVMAsmPrinter.a lib/libLLVMDebugInfoCodeView.a lib/libLLVMDebugInfoMSF.a lib/libLLVMSelectionDAG.a lib/libLLVMXCoreDesc.a lib/libLLVMXCoreAsmPrinter.a lib/libLLVMXCoreDisassembler.a lib/libLLVMXCoreInfo.a lib/libLLVMMCDisassembler.a lib/libLLVMLTO.a lib/libLLVMObjCARCOpts.a lib/libLLVMDebugInfoDWARF.a lib/libLLVMPasses.a lib/libLLVMCodeGen.a lib/libLLVMTarget.a lib/libLLVMBitWriter.a lib/libLLVMipo.a lib/libLLVMLinker.a lib/libLLVMIRReader.a lib/libLLVMAsmParser.a lib/libLLVMScalarOpts.a lib/libLLVMVectorize.a lib/libLLVMInstCombine.a lib/libLLVMInstrumentation.a lib/libLLVMTransformUtils.a lib/libLLVMAnalysis.a lib/libLLVMObject.a lib/libLLVMBitReader.a lib/libLLVMMCParser.a lib/libLLVMMC.a lib/libLLVMProfileData.a lib/libLLVMCore.a lib/libLLVMSupport.a lib/libLLVMDemangle.a -lcurses -lz -lm -Wl,-rpath,@loader_path/../lib && cd /b/c/b/ClangToTMacdbg_/src/third_party/llvm-build/Release+Asserts/tools/lld/tools/lld && /b/c/b/ClangToTMacdbg_/src/third_party/llvm-build-tools/cmake343/bin/cmake -E create_symlink lld /b/c/b/ClangToTMacdbg_/src/third_party/llvm-build/Release+Asserts/./bin/lld-link && cd /b/c/b/ClangToTMacdbg_/src/third_party/llvm-build/Release+Asserts/tools/lld/tools/lld && /b/c/b/ClangToTMacdbg_/src/third_party/llvm-build-tools/cmake343/bin/cmake -E create_symlink lld /b/c/b/ClangToTMacdbg_/src/third_party/llvm-build/Release+Asserts/./bin/ld.lld
Undefined symbols for architecture x86_64:

"std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > lld::elf::toString<llvm::object::ELFType<(llvm::support::endianness)0, true> >(lld::elf::InputSectionBase<llvm::object::ELFType<(llvm::support::endianness)0, true> > const*)", referenced from:
    void lld::elf::EhOutputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >::addSectionAux<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, true> >(lld::elf::EhInputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >*, llvm::ArrayRef<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, true> >) in liblldELF.a(OutputSections.cpp.o)
    void lld::elf::EhOutputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >::addSectionAux<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, false> >(lld::elf::EhInputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >*, llvm::ArrayRef<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, false> >) in liblldELF.a(OutputSections.cpp.o)
    lld::elf::CieRecord* lld::elf::EhOutputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >::addCie<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, true> >(lld::elf::EhSectionPiece&, llvm::ArrayRef<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, true> >) in liblldELF.a(OutputSections.cpp.o)
    bool lld::elf::EhOutputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >::isFdeLive<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, true> >(lld::elf::EhSectionPiece&, llvm::ArrayRef<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, true> >) in liblldELF.a(OutputSections.cpp.o)
    lld::elf::CieRecord* lld::elf::EhOutputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >::addCie<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, false> >(lld::elf::EhSectionPiece&, llvm::ArrayRef<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, false> >) in liblldELF.a(OutputSections.cpp.o)
    bool lld::elf::EhOutputSection<llvm::object::ELFType<(llvm::support::endianness)0, true> >::isFdeLive<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, false> >(lld::elf::EhSectionPiece&, llvm::ArrayRef<llvm::object::Elf_Rel_Impl<llvm::object::ELFType<(llvm::support::endianness)0, true>, false> >) in liblldELF.a(OutputSections.cpp.o)

Last good build at r287912, first bad at r287919. This looks like the most likely culprit.

https://build.chromium.org/p/chromium.fyi/builders/ClangToTMac%20%28dbg%29/builds/7110/steps/gclient%20runhooks/logs/stdio

ELF/OutputSections.h

public:
 
   size_t NumFdes = 0;
 
 private:
   template <class RelTy>
   void addSectionAux(EhInputSection<ELFT> *S, llvm::ArrayRef<RelTy> Rels);
 
   template <class RelTy>
-  CieRecord *addCie(EhSectionPiece &Piece, EhInputSection<ELFT> *Sec,
-                    ArrayRef<RelTy> Rels);
+  CieRecord *addCie(EhSectionPiece &Piece, ArrayRef<RelTy> Rels);
 
   template <class RelTy>
-  bool isFdeLive(EhSectionPiece &Piece, EhInputSection<ELFT> *Sec,
-                 ArrayRef<RelTy> Rels);
+  bool isFdeLive(EhSectionPiece &Piece, ArrayRef<RelTy> Rels);
 
   uintX_t getFdePc(uint8_t *Buf, size_t Off, uint8_t Enc);
 
   std::vector<EhInputSection<ELFT> *> Sections;
   std::vector<CieRecord *> Cies;
 
   // CIE records are uniquified by their contents and personality functions.
   llvm::DenseMap<std::pair<ArrayRef<uint8_t>, SymbolBody *>, CieRecord> CieMap;

ELF/OutputSections.cpp

EhOutputSection<ELFT>::EhOutputSection()
     : OutputSectionBase(".eh_frame", SHT_PROGBITS, SHF_ALLOC) {}
 
 // Search for an existing CIE record or create a new one.
 // CIE records from input object files are uniquified by their contents
 // and where their relocations point to.
 template <class ELFT>
 template <class RelTy>
 CieRecord *EhOutputSection<ELFT>::addCie(EhSectionPiece &Piece,
-                                         EhInputSection<ELFT> *Sec,
                                          ArrayRef<RelTy> Rels) {
+  EhInputSection<ELFT> *Sec = cast<EhInputSection<ELFT>>(Piece.ID);
   const endianness E = ELFT::TargetEndianness;
   if (read32<E>(Piece.data().data() + 4) != 0)
-    fatal("CIE expected at beginning of .eh_frame: " + Sec->Name);
+    fatal(toString(Sec) + ": CIE expected at beginning of .eh_frame");
 
   SymbolBody *Personality = nullptr;
   unsigned FirstRelI = Piece.FirstRelocation;
   if (FirstRelI != (unsigned)-1)
     Personality = &Sec->getFile()->getRelocTargetSym(Rels[FirstRelI]);
 
   // Search for an existing CIE by CIE contents/relocation target pair.
   CieRecord *Cie = &CieMap[{Piece.data(), Personality}];
 
   // If not found, create a new one.
   if (Cie->Piece == nullptr) {
     Cie->Piece = &Piece;
     Cies.push_back(Cie);
   }
   return Cie;
 }
 
 // There is one FDE per function. Returns true if a given FDE
 // points to a live function.
 template <class ELFT>
 template <class RelTy>
 bool EhOutputSection<ELFT>::isFdeLive(EhSectionPiece &Piece,
-                                      EhInputSection<ELFT> *Sec,
                                       ArrayRef<RelTy> Rels) {
+  EhInputSection<ELFT> *Sec = cast<EhInputSection<ELFT>>(Piece.ID);
   unsigned FirstRelI = Piece.FirstRelocation;
   if (FirstRelI == (unsigned)-1)
-    fatal("FDE doesn't reference another section");
+    fatal(toString(Sec) + ": FDE doesn't reference another section");
   const RelTy &Rel = Rels[FirstRelI];
   SymbolBody &B = Sec->getFile()->getRelocTargetSym(Rel);
   auto *D = dyn_cast<DefinedRegular<ELFT>>(&B);
   if (!D || !D->Section)
     return false;
   InputSectionBase<ELFT> *Target = D->Section->Repl;
   return Target && Target->Live;
 }
void EhOutputSection<ELFT>::addSectionAux(EhInputSection<ELFT> *Sec,
   for (EhSectionPiece &Piece : Sec->Pieces) {
     // The empty record is the end marker.
     if (Piece.size() == 4)
       return;
 
     size_t Offset = Piece.InputOff;
     uint32_t ID = read32<E>(Piece.data().data() + 4);
     if (ID == 0) {
-      OffsetToCie[Offset] = addCie(Piece, Sec, Rels);
+      OffsetToCie[Offset] = addCie(Piece, Rels);
       continue;
     }
 
     uint32_t CieOffset = Offset + 4 - ID;
     CieRecord *Cie = OffsetToCie[CieOffset];
     if (!Cie)
-      fatal("invalid CIE reference");
+      fatal(toString(Sec) + ": invalid CIE reference");
 
-    if (!isFdeLive(Piece, Sec, Rels))
+    if (!isFdeLive(Piece, Rels))
       continue;
     Cie->FdePieces.push_back(&Piece);
     NumFdes++;
   }
 }
 
 template <class ELFT>
 void EhOutputSection<ELFT>::addSection(InputSectionData *C) {