1 //===- llvm/CodeGen/AddressPool.cpp - Dwarf Debug Framework ---------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "AddressPool.h" 10 #include "llvm/ADT/SmallVector.h" 11 #include "llvm/CodeGen/AsmPrinter.h" 12 #include "llvm/IR/DataLayout.h" 13 #include "llvm/MC/MCStreamer.h" 14 #include "llvm/Target/TargetLoweringObjectFile.h" 15 #include <utility> 16 17 using namespace llvm; 18 19 unsigned AddressPool::getIndex(const MCSymbol *Sym, bool TLS) { 20 resetUsedFlag(true); 21 auto IterBool = 22 Pool.insert(std::make_pair(Sym, AddressPoolEntry(Pool.size(), TLS))); 23 return IterBool.first->second.Number; 24 } 25 26 MCSymbol *AddressPool::emitHeader(AsmPrinter &Asm, MCSection *Section) { 27 static const uint8_t AddrSize = Asm.getDataLayout().getPointerSize(); 28 29 MCSymbol *EndLabel = 30 Asm.emitDwarfUnitLength("debug_addr", "Length of contribution"); 31 Asm.OutStreamer->AddComment("DWARF version number"); 32 Asm.emitInt16(Asm.getDwarfVersion()); 33 Asm.OutStreamer->AddComment("Address size"); 34 Asm.emitInt8(AddrSize); 35 Asm.OutStreamer->AddComment("Segment selector size"); 36 Asm.emitInt8(0); // TODO: Support non-zero segment_selector_size. 37 38 return EndLabel; 39 } 40 41 // Emit addresses into the section given. 42 void AddressPool::emit(AsmPrinter &Asm, MCSection *AddrSection) { 43 if (isEmpty()) 44 return; 45 46 // Start the dwarf addr section. 47 Asm.OutStreamer->switchSection(AddrSection); 48 49 MCSymbol *EndLabel = nullptr; 50 51 if (Asm.getDwarfVersion() >= 5) 52 EndLabel = emitHeader(Asm, AddrSection); 53 54 // Define the symbol that marks the start of the contribution. 55 // It is referenced via DW_AT_addr_base. 56 Asm.OutStreamer->emitLabel(AddressTableBaseSym); 57 58 // Order the address pool entries by ID 59 SmallVector<const MCExpr *, 64> Entries(Pool.size()); 60 61 for (const auto &I : Pool) 62 Entries[I.second.Number] = 63 I.second.TLS 64 ? Asm.getObjFileLowering().getDebugThreadLocalSymbol(I.first) 65 : MCSymbolRefExpr::create(I.first, Asm.OutContext); 66 67 for (const MCExpr *Entry : Entries) 68 Asm.OutStreamer->emitValue(Entry, Asm.getDataLayout().getPointerSize()); 69 70 if (EndLabel) 71 Asm.OutStreamer->emitLabel(EndLabel); 72 } 73