1 //===-- llvm/CodeGen/DwarfStringPool.cpp - Dwarf Debug Framework ----------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "DwarfStringPool.h" 11 #include "llvm/CodeGen/AsmPrinter.h" 12 #include "llvm/MC/MCAsmInfo.h" 13 #include "llvm/MC/MCStreamer.h" 14 15 using namespace llvm; 16 17 DwarfStringPool::DwarfStringPool(BumpPtrAllocator &A, AsmPrinter &Asm, 18 StringRef Prefix) 19 : Pool(A), Prefix(Prefix), 20 ShouldCreateSymbols(Asm.MAI->doesDwarfUseRelocationsAcrossSections()) {} 21 22 DwarfStringPool::EntryRef DwarfStringPool::getEntry(AsmPrinter &Asm, 23 StringRef Str) { 24 auto I = Pool.insert(std::make_pair(Str, EntryTy())); 25 if (I.second) { 26 auto &Entry = I.first->second; 27 Entry.Index = Pool.size() - 1; 28 Entry.Offset = NumBytes; 29 Entry.Symbol = ShouldCreateSymbols ? Asm.createTempSymbol(Prefix) : nullptr; 30 31 NumBytes += Str.size() + 1; 32 assert(NumBytes > Entry.Offset && "Unexpected overflow"); 33 } 34 return EntryRef(*I.first); 35 } 36 37 void DwarfStringPool::emit(AsmPrinter &Asm, MCSection *StrSection, 38 MCSection *OffsetSection) { 39 if (Pool.empty()) 40 return; 41 42 // Start the dwarf str section. 43 Asm.OutStreamer->SwitchSection(StrSection); 44 45 // Get all of the string pool entries and put them in an array by their ID so 46 // we can sort them. 47 SmallVector<const StringMapEntry<EntryTy> *, 64> Entries(Pool.size()); 48 49 for (const auto &E : Pool) 50 Entries[E.getValue().Index] = &E; 51 52 for (const auto &Entry : Entries) { 53 assert(ShouldCreateSymbols == static_cast<bool>(Entry->getValue().Symbol) && 54 "Mismatch between setting and entry"); 55 56 // Emit a label for reference from debug information entries. 57 if (ShouldCreateSymbols) 58 Asm.OutStreamer->EmitLabel(Entry->getValue().Symbol); 59 60 // Emit the string itself with a terminating null byte. 61 Asm.OutStreamer->AddComment("string offset=" + 62 Twine(Entry->getValue().Offset)); 63 Asm.OutStreamer->EmitBytes( 64 StringRef(Entry->getKeyData(), Entry->getKeyLength() + 1)); 65 } 66 67 // If we've got an offset section go ahead and emit that now as well. 68 if (OffsetSection) { 69 Asm.OutStreamer->SwitchSection(OffsetSection); 70 unsigned size = 4; // FIXME: DWARF64 is 8. 71 for (const auto &Entry : Entries) 72 Asm.OutStreamer->EmitIntValue(Entry->getValue().Offset, size); 73 } 74 } 75
