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
TargetMachine(const Target & T,StringRef DataLayoutString,const Triple & TT,StringRef CPU,StringRef FS,const TargetOptions & Options)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
~TargetMachine()52 TargetMachine::~TargetMachine() {
53 delete AsmInfo;
54 delete MRI;
55 delete MII;
56 delete STI;
57 }
58
isPositionIndependent() const59 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.
resetTargetOptions(const Function & F) const69 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.
getRelocationModel() const84 Reloc::Model TargetMachine::getRelocationModel() const { return RM; }
85
86 /// Returns the code model. The choices are small, kernel, medium, large, and
87 /// target default.
getCodeModel() const88 CodeModel::Model TargetMachine::getCodeModel() const { return CMModel; }
89
90 /// Get the IR-specified TLS model for Var.
getSelectedTLSModel(const GlobalValue * GV)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
shouldAssumeDSOLocal(const Module & M,const GlobalValue * GV) const111 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
getTLSModel(const GlobalValue * GV) const153 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.
getOptLevel() const181 CodeGenOpt::Level TargetMachine::getOptLevel() const { return OptLevel; }
182
setOptLevel(CodeGenOpt::Level Level)183 void TargetMachine::setOptLevel(CodeGenOpt::Level Level) { OptLevel = Level; }
184
getTargetIRAnalysis()185 TargetIRAnalysis TargetMachine::getTargetIRAnalysis() {
186 return TargetIRAnalysis([this](const Function &F) {
187 return TargetTransformInfo(F.getParent()->getDataLayout());
188 });
189 }
190
getNameWithPrefix(SmallVectorImpl<char> & Name,const GlobalValue * GV,Mangler & Mang,bool MayAlwaysUsePrivate) const191 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
getSymbol(const GlobalValue * GV,Mangler & Mang) const204 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