1 //===-- TargetMachine.cpp - General Target Information ---------------------==// 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 // This file describes the general parts of a Target machine. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Target/TargetMachine.h" 15 #include "llvm/Analysis/TargetTransformInfo.h" 16 #include "llvm/CodeGen/MachineFunction.h" 17 #include "llvm/IR/Function.h" 18 #include "llvm/IR/GlobalAlias.h" 19 #include "llvm/IR/GlobalValue.h" 20 #include "llvm/IR/GlobalVariable.h" 21 #include "llvm/IR/LegacyPassManager.h" 22 #include "llvm/IR/Mangler.h" 23 #include "llvm/MC/MCAsmInfo.h" 24 #include "llvm/MC/MCContext.h" 25 #include "llvm/MC/MCInstrInfo.h" 26 #include "llvm/MC/MCSectionMachO.h" 27 #include "llvm/MC/MCTargetOptions.h" 28 #include "llvm/MC/SectionKind.h" 29 #include "llvm/Target/TargetLowering.h" 30 #include "llvm/Target/TargetLoweringObjectFile.h" 31 #include "llvm/Target/TargetSubtargetInfo.h" 32 using namespace llvm; 33 34 cl::opt<bool> EnableIPRA("enable-ipra", cl::init(false), cl::Hidden, 35 cl::desc("Enable interprocedural register allocation " 36 "to reduce load/store at procedure calls.")); 37 38 //--------------------------------------------------------------------------- 39 // TargetMachine Class 40 // 41 42 TargetMachine::TargetMachine(const Target &T, StringRef DataLayoutString, 43 const Triple &TT, StringRef CPU, StringRef FS, 44 const TargetOptions &Options) 45 : TheTarget(T), DL(DataLayoutString), TargetTriple(TT), TargetCPU(CPU), 46 TargetFS(FS), AsmInfo(nullptr), MRI(nullptr), MII(nullptr), STI(nullptr), 47 RequireStructuredCFG(false), Options(Options) { 48 if (EnableIPRA.getNumOccurrences()) 49 this->Options.EnableIPRA = EnableIPRA; 50 } 51 52 TargetMachine::~TargetMachine() { 53 delete AsmInfo; 54 delete MRI; 55 delete MII; 56 delete STI; 57 } 58 59 bool TargetMachine::isPositionIndependent() const { 60 return getRelocationModel() == Reloc::PIC_; 61 } 62 63 /// \brief Reset the target options based on the function's attributes. 64 // FIXME: This function needs to go away for a number of reasons: 65 // a) global state on the TargetMachine is terrible in general, 66 // b) there's no default state here to keep, 67 // c) these target options should be passed only on the function 68 // and not on the TargetMachine (via TargetOptions) at all. 69 void TargetMachine::resetTargetOptions(const Function &F) const { 70 #define RESET_OPTION(X, Y) \ 71 do { \ 72 if (F.hasFnAttribute(Y)) \ 73 Options.X = (F.getFnAttribute(Y).getValueAsString() == "true"); \ 74 } while (0) 75 76 RESET_OPTION(LessPreciseFPMADOption, "less-precise-fpmad"); 77 RESET_OPTION(UnsafeFPMath, "unsafe-fp-math"); 78 RESET_OPTION(NoInfsFPMath, "no-infs-fp-math"); 79 RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math"); 80 } 81 82 /// Returns the code generation relocation model. The choices are static, PIC, 83 /// and dynamic-no-pic. 84 Reloc::Model TargetMachine::getRelocationModel() const { return RM; } 85 86 /// Returns the code model. The choices are small, kernel, medium, large, and 87 /// target default. 88 CodeModel::Model TargetMachine::getCodeModel() const { return CMModel; } 89 90 /// Get the IR-specified TLS model for Var. 91 static TLSModel::Model getSelectedTLSModel(const GlobalValue *GV) { 92 switch (GV->getThreadLocalMode()) { 93 case GlobalVariable::NotThreadLocal: 94 llvm_unreachable("getSelectedTLSModel for non-TLS variable"); 95 break; 96 case GlobalVariable::GeneralDynamicTLSModel: 97 return TLSModel::GeneralDynamic; 98 case GlobalVariable::LocalDynamicTLSModel: 99 return TLSModel::LocalDynamic; 100 case GlobalVariable::InitialExecTLSModel: 101 return TLSModel::InitialExec; 102 case GlobalVariable::LocalExecTLSModel: 103 return TLSModel::LocalExec; 104 } 105 llvm_unreachable("invalid TLS model"); 106 } 107 108 // FIXME: make this a proper option 109 static bool CanUseCopyRelocWithPIE = false; 110 111 bool TargetMachine::shouldAssumeDSOLocal(const Module &M, 112 const GlobalValue *GV) const { 113 Reloc::Model RM = getRelocationModel(); 114 const Triple &TT = getTargetTriple(); 115 116 // DLLImport explicitly marks the GV as external. 117 if (GV && GV->hasDLLImportStorageClass()) 118 return false; 119 120 // Every other GV is local on COFF 121 if (TT.isOSBinFormatCOFF()) 122 return true; 123 124 if (GV && (GV->hasLocalLinkage() || !GV->hasDefaultVisibility())) 125 return true; 126 127 if (TT.isOSBinFormatMachO()) { 128 if (RM == Reloc::Static) 129 return true; 130 return GV && GV->isStrongDefinitionForLinker(); 131 } 132 133 assert(TT.isOSBinFormatELF()); 134 assert(RM != Reloc::DynamicNoPIC); 135 136 bool IsExecutable = 137 RM == Reloc::Static || M.getPIELevel() != PIELevel::Default; 138 if (IsExecutable) { 139 // If the symbol is defined, it cannot be preempted. 140 if (GV && !GV->isDeclarationForLinker()) 141 return true; 142 143 bool IsTLS = GV && GV->isThreadLocal(); 144 // Check if we can use copy relocations. 145 if (!IsTLS && (RM == Reloc::Static || CanUseCopyRelocWithPIE)) 146 return true; 147 } 148 149 // ELF supports preemption of other symbols. 150 return false; 151 } 152 153 TLSModel::Model TargetMachine::getTLSModel(const GlobalValue *GV) const { 154 bool IsPIE = GV->getParent()->getPIELevel() != PIELevel::Default; 155 Reloc::Model RM = getRelocationModel(); 156 bool IsSharedLibrary = RM == Reloc::PIC_ && !IsPIE; 157 bool IsLocal = shouldAssumeDSOLocal(*GV->getParent(), GV); 158 159 TLSModel::Model Model; 160 if (IsSharedLibrary) { 161 if (IsLocal) 162 Model = TLSModel::LocalDynamic; 163 else 164 Model = TLSModel::GeneralDynamic; 165 } else { 166 if (IsLocal) 167 Model = TLSModel::LocalExec; 168 else 169 Model = TLSModel::InitialExec; 170 } 171 172 // If the user specified a more specific model, use that. 173 TLSModel::Model SelectedModel = getSelectedTLSModel(GV); 174 if (SelectedModel > Model) 175 return SelectedModel; 176 177 return Model; 178 } 179 180 /// Returns the optimization level: None, Less, Default, or Aggressive. 181 CodeGenOpt::Level TargetMachine::getOptLevel() const { return OptLevel; } 182 183 void TargetMachine::setOptLevel(CodeGenOpt::Level Level) { OptLevel = Level; } 184 185 TargetIRAnalysis TargetMachine::getTargetIRAnalysis() { 186 return TargetIRAnalysis([this](const Function &F) { 187 return TargetTransformInfo(F.getParent()->getDataLayout()); 188 }); 189 } 190 191 void TargetMachine::getNameWithPrefix(SmallVectorImpl<char> &Name, 192 const GlobalValue *GV, Mangler &Mang, 193 bool MayAlwaysUsePrivate) const { 194 if (MayAlwaysUsePrivate || !GV->hasPrivateLinkage()) { 195 // Simple case: If GV is not private, it is not important to find out if 196 // private labels are legal in this case or not. 197 Mang.getNameWithPrefix(Name, GV, false); 198 return; 199 } 200 const TargetLoweringObjectFile *TLOF = getObjFileLowering(); 201 TLOF->getNameWithPrefix(Name, GV, Mang, *this); 202 } 203 204 MCSymbol *TargetMachine::getSymbol(const GlobalValue *GV, Mangler &Mang) const { 205 SmallString<128> NameStr; 206 getNameWithPrefix(NameStr, GV, Mang); 207 const TargetLoweringObjectFile *TLOF = getObjFileLowering(); 208 return TLOF->getContext().getOrCreateSymbol(NameStr); 209 } 210
