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