1 //===-- TargetMachine.cpp - General Target Information ---------------------==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file describes the general parts of a Target machine.
12 //===----------------------------------------------------------------------===//
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"
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."));
38 //---------------------------------------------------------------------------
39 // TargetMachine Class
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), DefaultOptions(Options), Options(Options) {
48 if (EnableIPRA.getNumOccurrences())
49 this->Options.EnableIPRA = EnableIPRA;
52 TargetMachine::~TargetMachine() {
59 bool TargetMachine::isPositionIndependent() const {
60 return getRelocationModel() == Reloc::PIC_;
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) these target options should be passed only on the function
67 // and not on the TargetMachine (via TargetOptions) at all.
68 void TargetMachine::resetTargetOptions(const Function &F) const {
69 #define RESET_OPTION(X, Y) \
71 if (F.hasFnAttribute(Y)) \
72 Options.X = (F.getFnAttribute(Y).getValueAsString() == "true"); \
74 Options.X = DefaultOptions.X; \
77 RESET_OPTION(LessPreciseFPMADOption, "less-precise-fpmad");
78 RESET_OPTION(UnsafeFPMath, "unsafe-fp-math");
79 RESET_OPTION(NoInfsFPMath, "no-infs-fp-math");
80 RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math");
81 RESET_OPTION(NoTrappingFPMath, "no-trapping-math");
84 F.getFnAttribute("denormal-fp-math").getValueAsString();
85 if (Denormal == "ieee")
86 Options.FPDenormalMode = FPDenormal::IEEE;
87 else if (Denormal == "preserve-sign")
88 Options.FPDenormalMode = FPDenormal::PreserveSign;
89 else if (Denormal == "positive-zero")
90 Options.FPDenormalMode = FPDenormal::PositiveZero;
92 Options.FPDenormalMode = DefaultOptions.FPDenormalMode;
95 /// Returns the code generation relocation model. The choices are static, PIC,
96 /// and dynamic-no-pic.
97 Reloc::Model TargetMachine::getRelocationModel() const { return RM; }
99 /// Returns the code model. The choices are small, kernel, medium, large, and
101 CodeModel::Model TargetMachine::getCodeModel() const { return CMModel; }
103 /// Get the IR-specified TLS model for Var.
104 static TLSModel::Model getSelectedTLSModel(const GlobalValue *GV) {
105 switch (GV->getThreadLocalMode()) {
106 case GlobalVariable::NotThreadLocal:
107 llvm_unreachable("getSelectedTLSModel for non-TLS variable");
109 case GlobalVariable::GeneralDynamicTLSModel:
110 return TLSModel::GeneralDynamic;
111 case GlobalVariable::LocalDynamicTLSModel:
112 return TLSModel::LocalDynamic;
113 case GlobalVariable::InitialExecTLSModel:
114 return TLSModel::InitialExec;
115 case GlobalVariable::LocalExecTLSModel:
116 return TLSModel::LocalExec;
118 llvm_unreachable("invalid TLS model");
121 bool TargetMachine::shouldAssumeDSOLocal(const Module &M,
122 const GlobalValue *GV) const {
123 Reloc::Model RM = getRelocationModel();
124 const Triple &TT = getTargetTriple();
126 // DLLImport explicitly marks the GV as external.
127 if (GV && GV->hasDLLImportStorageClass())
130 // Every other GV is local on COFF.
131 // Make an exception for windows OS in the triple: Some firmwares builds use
132 // *-win32-macho triples. This (accidentally?) produced windows relocations
133 // without GOT tables in older clang versions; Keep this behaviour.
134 if (TT.isOSBinFormatCOFF() || (TT.isOSWindows() && TT.isOSBinFormatMachO()))
137 if (GV && (GV->hasLocalLinkage() || !GV->hasDefaultVisibility()))
140 if (TT.isOSBinFormatMachO()) {
141 if (RM == Reloc::Static)
143 return GV && GV->isStrongDefinitionForLinker();
146 assert(TT.isOSBinFormatELF());
147 assert(RM != Reloc::DynamicNoPIC);
150 RM == Reloc::Static || M.getPIELevel() != PIELevel::Default;
152 // If the symbol is defined, it cannot be preempted.
153 if (GV && !GV->isDeclarationForLinker())
156 bool IsTLS = GV && GV->isThreadLocal();
157 bool IsAccessViaCopyRelocs =
158 Options.MCOptions.MCPIECopyRelocations && GV && isa<GlobalVariable>(GV);
159 // Check if we can use copy relocations.
160 if (!IsTLS && (RM == Reloc::Static || IsAccessViaCopyRelocs))
164 // ELF supports preemption of other symbols.
168 TLSModel::Model TargetMachine::getTLSModel(const GlobalValue *GV) const {
169 bool IsPIE = GV->getParent()->getPIELevel() != PIELevel::Default;
170 Reloc::Model RM = getRelocationModel();
171 bool IsSharedLibrary = RM == Reloc::PIC_ && !IsPIE;
172 bool IsLocal = shouldAssumeDSOLocal(*GV->getParent(), GV);
174 TLSModel::Model Model;
175 if (IsSharedLibrary) {
177 Model = TLSModel::LocalDynamic;
179 Model = TLSModel::GeneralDynamic;
182 Model = TLSModel::LocalExec;
184 Model = TLSModel::InitialExec;
187 // If the user specified a more specific model, use that.
188 TLSModel::Model SelectedModel = getSelectedTLSModel(GV);
189 if (SelectedModel > Model)
190 return SelectedModel;
195 /// Returns the optimization level: None, Less, Default, or Aggressive.
196 CodeGenOpt::Level TargetMachine::getOptLevel() const { return OptLevel; }
198 void TargetMachine::setOptLevel(CodeGenOpt::Level Level) { OptLevel = Level; }
200 TargetIRAnalysis TargetMachine::getTargetIRAnalysis() {
201 return TargetIRAnalysis([this](const Function &F) {
202 return TargetTransformInfo(F.getParent()->getDataLayout());
206 void TargetMachine::getNameWithPrefix(SmallVectorImpl<char> &Name,
207 const GlobalValue *GV, Mangler &Mang,
208 bool MayAlwaysUsePrivate) const {
209 if (MayAlwaysUsePrivate || !GV->hasPrivateLinkage()) {
210 // Simple case: If GV is not private, it is not important to find out if
211 // private labels are legal in this case or not.
212 Mang.getNameWithPrefix(Name, GV, false);
215 const TargetLoweringObjectFile *TLOF = getObjFileLowering();
216 TLOF->getNameWithPrefix(Name, GV, *this);
219 MCSymbol *TargetMachine::getSymbol(const GlobalValue *GV) const {
220 const TargetLoweringObjectFile *TLOF = getObjFileLowering();
221 SmallString<128> NameStr;
222 getNameWithPrefix(NameStr, GV, TLOF->getMangler());
223 return TLOF->getContext().getOrCreateSymbol(NameStr);