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 HasBeenUsed = 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 StringRef Prefix = "debug_addr_"; 29 MCSymbol *BeginLabel = Asm.createTempSymbol(Prefix + "start"); 30 MCSymbol *EndLabel = Asm.createTempSymbol(Prefix + "end"); 31 32 Asm.emitDwarfUnitLength(EndLabel, BeginLabel, "Length of contribution"); 33 Asm.OutStreamer->emitLabel(BeginLabel); 34 Asm.OutStreamer->AddComment("DWARF version number"); 35 Asm.emitInt16(Asm.getDwarfVersion()); 36 Asm.OutStreamer->AddComment("Address size"); 37 Asm.emitInt8(AddrSize); 38 Asm.OutStreamer->AddComment("Segment selector size"); 39 Asm.emitInt8(0); // TODO: Support non-zero segment_selector_size. 40 41 return EndLabel; 42 } 43 44 // Emit addresses into the section given. 45 void AddressPool::emit(AsmPrinter &Asm, MCSection *AddrSection) { 46 if (isEmpty()) 47 return; 48 49 // Start the dwarf addr section. 50 Asm.OutStreamer->SwitchSection(AddrSection); 51 52 MCSymbol *EndLabel = nullptr; 53 54 if (Asm.getDwarfVersion() >= 5) 55 EndLabel = emitHeader(Asm, AddrSection); 56 57 // Define the symbol that marks the start of the contribution. 58 // It is referenced via DW_AT_addr_base. 59 Asm.OutStreamer->emitLabel(AddressTableBaseSym); 60 61 // Order the address pool entries by ID 62 SmallVector<const MCExpr *, 64> Entries(Pool.size()); 63 64 for (const auto &I : Pool) 65 Entries[I.second.Number] = 66 I.second.TLS 67 ? Asm.getObjFileLowering().getDebugThreadLocalSymbol(I.first) 68 : MCSymbolRefExpr::create(I.first, Asm.OutContext); 69 70 for (const MCExpr *Entry : Entries) 71 Asm.OutStreamer->emitValue(Entry, Asm.getDataLayout().getPointerSize()); 72 73 if (EndLabel) 74 Asm.OutStreamer->emitLabel(EndLabel); 75 } 76