1//===-- X86TargetObjectFile.cpp - X86 Object Info -------------------------===// 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 "X86TargetObjectFile.h" 11#include "llvm/ADT/StringExtras.h" 12#include "llvm/IR/Mangler.h" 13#include "llvm/IR/Operator.h" 14#include "llvm/MC/MCContext.h" 15#include "llvm/MC/MCExpr.h" 16#include "llvm/MC/MCSectionCOFF.h" 17#include "llvm/MC/MCSectionELF.h" 18#include "llvm/MC/MCValue.h" 19#include "llvm/Support/COFF.h" 20#include "llvm/Support/Dwarf.h" 21#include "llvm/Target/TargetLowering.h" 22 23using namespace llvm; 24using namespace dwarf; 25 26const MCExpr *X86_64MachoTargetObjectFile::getTTypeGlobalReference( 27 const GlobalValue *GV, unsigned Encoding, Mangler &Mang, 28 const TargetMachine &TM, MachineModuleInfo *MMI, 29 MCStreamer &Streamer) const { 30 31 // On Darwin/X86-64, we can reference dwarf symbols with foo@GOTPCREL+4, which 32 // is an indirect pc-relative reference. 33 if ((Encoding & DW_EH_PE_indirect) && (Encoding & DW_EH_PE_pcrel)) { 34 const MCSymbol *Sym = TM.getSymbol(GV, Mang); 35 const MCExpr *Res = 36 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext()); 37 const MCExpr *Four = MCConstantExpr::create(4, getContext()); 38 return MCBinaryExpr::createAdd(Res, Four, getContext()); 39 } 40 41 return TargetLoweringObjectFileMachO::getTTypeGlobalReference( 42 GV, Encoding, Mang, TM, MMI, Streamer); 43} 44 45MCSymbol *X86_64MachoTargetObjectFile::getCFIPersonalitySymbol( 46 const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM, 47 MachineModuleInfo *MMI) const { 48 return TM.getSymbol(GV, Mang); 49} 50 51const MCExpr *X86_64MachoTargetObjectFile::getIndirectSymViaGOTPCRel( 52 const MCSymbol *Sym, const MCValue &MV, int64_t Offset, 53 MachineModuleInfo *MMI, MCStreamer &Streamer) const { 54 // On Darwin/X86-64, we need to use foo@GOTPCREL+4 to access the got entry 55 // from a data section. In case there's an additional offset, then use 56 // foo@GOTPCREL+4+<offset>. 57 unsigned FinalOff = Offset+MV.getConstant()+4; 58 const MCExpr *Res = 59 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext()); 60 const MCExpr *Off = MCConstantExpr::create(FinalOff, getContext()); 61 return MCBinaryExpr::createAdd(Res, Off, getContext()); 62} 63 64const MCExpr *X86ELFTargetObjectFile::getDebugThreadLocalSymbol( 65 const MCSymbol *Sym) const { 66 return MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext()); 67} 68 69void 70X86LinuxNaClTargetObjectFile::Initialize(MCContext &Ctx, 71 const TargetMachine &TM) { 72 TargetLoweringObjectFileELF::Initialize(Ctx, TM); 73 InitializeELF(TM.Options.UseInitArray); 74} 75 76const MCExpr *X86WindowsTargetObjectFile::lowerRelativeReference( 77 const GlobalValue *LHS, const GlobalValue *RHS, Mangler &Mang, 78 const TargetMachine &TM) const { 79 // Our symbols should exist in address space zero, cowardly no-op if 80 // otherwise. 81 if (LHS->getType()->getPointerAddressSpace() != 0 || 82 RHS->getType()->getPointerAddressSpace() != 0) 83 return nullptr; 84 85 // Both ptrtoint instructions must wrap global objects: 86 // - Only global variables are eligible for image relative relocations. 87 // - The subtrahend refers to the special symbol __ImageBase, a GlobalVariable. 88 // We expect __ImageBase to be a global variable without a section, externally 89 // defined. 90 // 91 // It should look something like this: @__ImageBase = external constant i8 92 if (!isa<GlobalObject>(LHS) || !isa<GlobalVariable>(RHS) || 93 LHS->isThreadLocal() || RHS->isThreadLocal() || 94 RHS->getName() != "__ImageBase" || !RHS->hasExternalLinkage() || 95 cast<GlobalVariable>(RHS)->hasInitializer() || RHS->hasSection()) 96 return nullptr; 97 98 return MCSymbolRefExpr::create( 99 TM.getSymbol(LHS, Mang), MCSymbolRefExpr::VK_COFF_IMGREL32, getContext()); 100} 101 102static std::string APIntToHexString(const APInt &AI) { 103 unsigned Width = (AI.getBitWidth() / 8) * 2; 104 std::string HexString = utohexstr(AI.getLimitedValue(), /*LowerCase=*/true); 105 unsigned Size = HexString.size(); 106 assert(Width >= Size && "hex string is too large!"); 107 HexString.insert(HexString.begin(), Width - Size, '0'); 108 109 return HexString; 110} 111 112static std::string scalarConstantToHexString(const Constant *C) { 113 Type *Ty = C->getType(); 114 if (isa<UndefValue>(C)) { 115 return APIntToHexString(APInt::getNullValue(Ty->getPrimitiveSizeInBits())); 116 } else if (const auto *CFP = dyn_cast<ConstantFP>(C)) { 117 return APIntToHexString(CFP->getValueAPF().bitcastToAPInt()); 118 } else if (const auto *CI = dyn_cast<ConstantInt>(C)) { 119 return APIntToHexString(CI->getValue()); 120 } else { 121 unsigned NumElements; 122 if (isa<VectorType>(Ty)) 123 NumElements = Ty->getVectorNumElements(); 124 else 125 NumElements = Ty->getArrayNumElements(); 126 std::string HexString; 127 for (int I = NumElements - 1, E = -1; I != E; --I) 128 HexString += scalarConstantToHexString(C->getAggregateElement(I)); 129 return HexString; 130 } 131} 132 133MCSection *X86WindowsTargetObjectFile::getSectionForConstant( 134 const DataLayout &DL, SectionKind Kind, const Constant *C, 135 unsigned &Align) const { 136 if (Kind.isMergeableConst() && C) { 137 const unsigned Characteristics = COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 138 COFF::IMAGE_SCN_MEM_READ | 139 COFF::IMAGE_SCN_LNK_COMDAT; 140 std::string COMDATSymName; 141 if (Kind.isMergeableConst4()) { 142 if (Align <= 4) { 143 COMDATSymName = "__real@" + scalarConstantToHexString(C); 144 Align = 4; 145 } 146 } else if (Kind.isMergeableConst8()) { 147 if (Align <= 8) { 148 COMDATSymName = "__real@" + scalarConstantToHexString(C); 149 Align = 8; 150 } 151 } else if (Kind.isMergeableConst16()) { 152 if (Align <= 16) { 153 COMDATSymName = "__xmm@" + scalarConstantToHexString(C); 154 Align = 16; 155 } 156 } else if (Kind.isMergeableConst32()) { 157 if (Align <= 32) { 158 COMDATSymName = "__ymm@" + scalarConstantToHexString(C); 159 Align = 32; 160 } 161 } 162 163 if (!COMDATSymName.empty()) 164 return getContext().getCOFFSection(".rdata", Characteristics, Kind, 165 COMDATSymName, 166 COFF::IMAGE_COMDAT_SELECT_ANY); 167 } 168 169 return TargetLoweringObjectFile::getSectionForConstant(DL, Kind, C, Align); 170} 171