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/CodeGen/MachineFunction.h"
16 #include "llvm/IR/Function.h"
17 #include "llvm/IR/GlobalAlias.h"
18 #include "llvm/IR/GlobalValue.h"
19 #include "llvm/IR/GlobalVariable.h"
20 #include "llvm/IR/Mangler.h"
21 #include "llvm/MC/MCAsmInfo.h"
22 #include "llvm/MC/MCCodeGenInfo.h"
23 #include "llvm/MC/MCContext.h"
24 #include "llvm/MC/MCSectionMachO.h"
25 #include "llvm/MC/MCTargetOptions.h"
26 #include "llvm/MC/SectionKind.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Target/TargetLowering.h"
29 #include "llvm/Target/TargetLoweringObjectFile.h"
30 #include "llvm/Target/TargetSubtargetInfo.h"
31 using namespace llvm;
32
33 //---------------------------------------------------------------------------
34 // TargetMachine Class
35 //
36
TargetMachine(const Target & T,StringRef TT,StringRef CPU,StringRef FS,const TargetOptions & Options)37 TargetMachine::TargetMachine(const Target &T,
38 StringRef TT, StringRef CPU, StringRef FS,
39 const TargetOptions &Options)
40 : TheTarget(T), TargetTriple(TT), TargetCPU(CPU), TargetFS(FS),
41 CodeGenInfo(nullptr), AsmInfo(nullptr),
42 RequireStructuredCFG(false),
43 Options(Options) {
44 }
45
~TargetMachine()46 TargetMachine::~TargetMachine() {
47 delete CodeGenInfo;
48 delete AsmInfo;
49 }
50
51 /// \brief Reset the target options based on the function's attributes.
resetTargetOptions(const Function & F) const52 void TargetMachine::resetTargetOptions(const Function &F) const {
53 #define RESET_OPTION(X, Y) \
54 do { \
55 if (F.hasFnAttribute(Y)) \
56 Options.X = (F.getAttributes() \
57 .getAttribute(AttributeSet::FunctionIndex, Y) \
58 .getValueAsString() == "true"); \
59 } while (0)
60
61 RESET_OPTION(NoFramePointerElim, "no-frame-pointer-elim");
62 RESET_OPTION(LessPreciseFPMADOption, "less-precise-fpmad");
63 RESET_OPTION(UnsafeFPMath, "unsafe-fp-math");
64 RESET_OPTION(NoInfsFPMath, "no-infs-fp-math");
65 RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math");
66 RESET_OPTION(UseSoftFloat, "use-soft-float");
67 RESET_OPTION(DisableTailCalls, "disable-tail-calls");
68
69 Options.MCOptions.SanitizeAddress = F.hasFnAttribute(Attribute::SanitizeAddress);
70 }
71
72 /// getRelocationModel - Returns the code generation relocation model. The
73 /// choices are static, PIC, and dynamic-no-pic, and target default.
getRelocationModel() const74 Reloc::Model TargetMachine::getRelocationModel() const {
75 if (!CodeGenInfo)
76 return Reloc::Default;
77 return CodeGenInfo->getRelocationModel();
78 }
79
80 /// getCodeModel - Returns the code model. The choices are small, kernel,
81 /// medium, large, and target default.
getCodeModel() const82 CodeModel::Model TargetMachine::getCodeModel() const {
83 if (!CodeGenInfo)
84 return CodeModel::Default;
85 return CodeGenInfo->getCodeModel();
86 }
87
88 /// Get the IR-specified TLS model for Var.
getSelectedTLSModel(const GlobalValue * GV)89 static TLSModel::Model getSelectedTLSModel(const GlobalValue *GV) {
90 switch (GV->getThreadLocalMode()) {
91 case GlobalVariable::NotThreadLocal:
92 llvm_unreachable("getSelectedTLSModel for non-TLS variable");
93 break;
94 case GlobalVariable::GeneralDynamicTLSModel:
95 return TLSModel::GeneralDynamic;
96 case GlobalVariable::LocalDynamicTLSModel:
97 return TLSModel::LocalDynamic;
98 case GlobalVariable::InitialExecTLSModel:
99 return TLSModel::InitialExec;
100 case GlobalVariable::LocalExecTLSModel:
101 return TLSModel::LocalExec;
102 }
103 llvm_unreachable("invalid TLS model");
104 }
105
getTLSModel(const GlobalValue * GV) const106 TLSModel::Model TargetMachine::getTLSModel(const GlobalValue *GV) const {
107 bool isLocal = GV->hasLocalLinkage();
108 bool isDeclaration = GV->isDeclaration();
109 bool isPIC = getRelocationModel() == Reloc::PIC_;
110 bool isPIE = Options.PositionIndependentExecutable;
111 // FIXME: what should we do for protected and internal visibility?
112 // For variables, is internal different from hidden?
113 bool isHidden = GV->hasHiddenVisibility();
114
115 TLSModel::Model Model;
116 if (isPIC && !isPIE) {
117 if (isLocal || isHidden)
118 Model = TLSModel::LocalDynamic;
119 else
120 Model = TLSModel::GeneralDynamic;
121 } else {
122 if (!isDeclaration || isHidden)
123 Model = TLSModel::LocalExec;
124 else
125 Model = TLSModel::InitialExec;
126 }
127
128 // If the user specified a more specific model, use that.
129 TLSModel::Model SelectedModel = getSelectedTLSModel(GV);
130 if (SelectedModel > Model)
131 return SelectedModel;
132
133 return Model;
134 }
135
136 /// getOptLevel - Returns the optimization level: None, Less,
137 /// Default, or Aggressive.
getOptLevel() const138 CodeGenOpt::Level TargetMachine::getOptLevel() const {
139 if (!CodeGenInfo)
140 return CodeGenOpt::Default;
141 return CodeGenInfo->getOptLevel();
142 }
143
setOptLevel(CodeGenOpt::Level Level) const144 void TargetMachine::setOptLevel(CodeGenOpt::Level Level) const {
145 if (CodeGenInfo)
146 CodeGenInfo->setOptLevel(Level);
147 }
148
getAsmVerbosityDefault() const149 bool TargetMachine::getAsmVerbosityDefault() const {
150 return Options.MCOptions.AsmVerbose;
151 }
152
setAsmVerbosityDefault(bool V)153 void TargetMachine::setAsmVerbosityDefault(bool V) {
154 Options.MCOptions.AsmVerbose = V;
155 }
156
getFunctionSections() const157 bool TargetMachine::getFunctionSections() const {
158 return Options.FunctionSections;
159 }
160
getDataSections() const161 bool TargetMachine::getDataSections() const {
162 return Options.DataSections;
163 }
164
setFunctionSections(bool V)165 void TargetMachine::setFunctionSections(bool V) {
166 Options.FunctionSections = V;
167 }
168
setDataSections(bool V)169 void TargetMachine::setDataSections(bool V) {
170 Options.DataSections = V;
171 }
172
canUsePrivateLabel(const MCAsmInfo & AsmInfo,const MCSection & Section)173 static bool canUsePrivateLabel(const MCAsmInfo &AsmInfo,
174 const MCSection &Section) {
175 if (!AsmInfo.isSectionAtomizableBySymbols(Section))
176 return true;
177
178 // If it is not dead stripped, it is safe to use private labels.
179 const MCSectionMachO &SMO = cast<MCSectionMachO>(Section);
180 if (SMO.hasAttribute(MachO::S_ATTR_NO_DEAD_STRIP))
181 return true;
182
183 return false;
184 }
185
getNameWithPrefix(SmallVectorImpl<char> & Name,const GlobalValue * GV,Mangler & Mang,bool MayAlwaysUsePrivate) const186 void TargetMachine::getNameWithPrefix(SmallVectorImpl<char> &Name,
187 const GlobalValue *GV, Mangler &Mang,
188 bool MayAlwaysUsePrivate) const {
189 if (MayAlwaysUsePrivate || !GV->hasPrivateLinkage()) {
190 // Simple case: If GV is not private, it is not important to find out if
191 // private labels are legal in this case or not.
192 Mang.getNameWithPrefix(Name, GV, false);
193 return;
194 }
195 SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, *this);
196 const TargetLoweringObjectFile &TLOF =
197 getSubtargetImpl()->getTargetLowering()->getObjFileLowering();
198 const MCSection *TheSection = TLOF.SectionForGlobal(GV, GVKind, Mang, *this);
199 bool CannotUsePrivateLabel = !canUsePrivateLabel(*AsmInfo, *TheSection);
200 Mang.getNameWithPrefix(Name, GV, CannotUsePrivateLabel);
201 }
202
getSymbol(const GlobalValue * GV,Mangler & Mang) const203 MCSymbol *TargetMachine::getSymbol(const GlobalValue *GV, Mangler &Mang) const {
204 SmallString<60> NameStr;
205 getNameWithPrefix(NameStr, GV, Mang);
206 const TargetLoweringObjectFile &TLOF =
207 getSubtargetImpl()->getTargetLowering()->getObjFileLowering();
208 return TLOF.getContext().GetOrCreateSymbol(NameStr.str());
209 }
210