TargetMachine.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
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/SectionKind.h"
25#include "llvm/Support/CommandLine.h"
26#include "llvm/Target/TargetLowering.h"
27#include "llvm/Target/TargetLoweringObjectFile.h"
28using namespace llvm;
29
30//---------------------------------------------------------------------------
31// Command-line options that tend to be useful on more than one back-end.
32//
33
34namespace llvm {
35  bool HasDivModLibcall;
36  bool AsmVerbosityDefault(false);
37}
38
39static cl::opt<bool>
40DataSections("fdata-sections",
41  cl::desc("Emit data into separate sections"),
42  cl::init(false));
43static cl::opt<bool>
44FunctionSections("ffunction-sections",
45  cl::desc("Emit functions into separate sections"),
46  cl::init(false));
47
48//---------------------------------------------------------------------------
49// TargetMachine Class
50//
51
52TargetMachine::TargetMachine(const Target &T,
53                             StringRef TT, StringRef CPU, StringRef FS,
54                             const TargetOptions &Options)
55  : TheTarget(T), TargetTriple(TT), TargetCPU(CPU), TargetFS(FS),
56    CodeGenInfo(0), AsmInfo(0),
57    MCRelaxAll(false),
58    MCNoExecStack(false),
59    MCSaveTempLabels(false),
60    MCUseCFI(true),
61    MCUseDwarfDirectory(false),
62    RequireStructuredCFG(false),
63    Options(Options) {
64}
65
66TargetMachine::~TargetMachine() {
67  delete CodeGenInfo;
68  delete AsmInfo;
69}
70
71/// \brief Reset the target options based on the function's attributes.
72void TargetMachine::resetTargetOptions(const MachineFunction *MF) const {
73  const Function *F = MF->getFunction();
74  TargetOptions &TO = MF->getTarget().Options;
75
76#define RESET_OPTION(X, Y)                                              \
77  do {                                                                  \
78    if (F->hasFnAttribute(Y))                                           \
79      TO.X =                                                            \
80        (F->getAttributes().                                            \
81           getAttribute(AttributeSet::FunctionIndex,                    \
82                        Y).getValueAsString() == "true");               \
83  } while (0)
84
85  RESET_OPTION(NoFramePointerElim, "no-frame-pointer-elim");
86  RESET_OPTION(LessPreciseFPMADOption, "less-precise-fpmad");
87  RESET_OPTION(UnsafeFPMath, "unsafe-fp-math");
88  RESET_OPTION(NoInfsFPMath, "no-infs-fp-math");
89  RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math");
90  RESET_OPTION(UseSoftFloat, "use-soft-float");
91  RESET_OPTION(DisableTailCalls, "disable-tail-calls");
92}
93
94/// getRelocationModel - Returns the code generation relocation model. The
95/// choices are static, PIC, and dynamic-no-pic, and target default.
96Reloc::Model TargetMachine::getRelocationModel() const {
97  if (!CodeGenInfo)
98    return Reloc::Default;
99  return CodeGenInfo->getRelocationModel();
100}
101
102/// getCodeModel - Returns the code model. The choices are small, kernel,
103/// medium, large, and target default.
104CodeModel::Model TargetMachine::getCodeModel() const {
105  if (!CodeGenInfo)
106    return CodeModel::Default;
107  return CodeGenInfo->getCodeModel();
108}
109
110/// Get the IR-specified TLS model for Var.
111static TLSModel::Model getSelectedTLSModel(const GlobalVariable *Var) {
112  switch (Var->getThreadLocalMode()) {
113  case GlobalVariable::NotThreadLocal:
114    llvm_unreachable("getSelectedTLSModel for non-TLS variable");
115    break;
116  case GlobalVariable::GeneralDynamicTLSModel:
117    return TLSModel::GeneralDynamic;
118  case GlobalVariable::LocalDynamicTLSModel:
119    return TLSModel::LocalDynamic;
120  case GlobalVariable::InitialExecTLSModel:
121    return TLSModel::InitialExec;
122  case GlobalVariable::LocalExecTLSModel:
123    return TLSModel::LocalExec;
124  }
125  llvm_unreachable("invalid TLS model");
126}
127
128TLSModel::Model TargetMachine::getTLSModel(const GlobalValue *GV) const {
129  // If GV is an alias then use the aliasee for determining
130  // thread-localness.
131  if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV))
132    GV = GA->getAliasedGlobal();
133  const GlobalVariable *Var = cast<GlobalVariable>(GV);
134
135  bool isLocal = Var->hasLocalLinkage();
136  bool isDeclaration = Var->isDeclaration();
137  bool isPIC = getRelocationModel() == Reloc::PIC_;
138  bool isPIE = Options.PositionIndependentExecutable;
139  // FIXME: what should we do for protected and internal visibility?
140  // For variables, is internal different from hidden?
141  bool isHidden = Var->hasHiddenVisibility();
142
143  TLSModel::Model Model;
144  if (isPIC && !isPIE) {
145    if (isLocal || isHidden)
146      Model = TLSModel::LocalDynamic;
147    else
148      Model = TLSModel::GeneralDynamic;
149  } else {
150    if (!isDeclaration || isHidden)
151      Model = TLSModel::LocalExec;
152    else
153      Model = TLSModel::InitialExec;
154  }
155
156  // If the user specified a more specific model, use that.
157  TLSModel::Model SelectedModel = getSelectedTLSModel(Var);
158  if (SelectedModel > Model)
159    return SelectedModel;
160
161  return Model;
162}
163
164/// getOptLevel - Returns the optimization level: None, Less,
165/// Default, or Aggressive.
166CodeGenOpt::Level TargetMachine::getOptLevel() const {
167  if (!CodeGenInfo)
168    return CodeGenOpt::Default;
169  return CodeGenInfo->getOptLevel();
170}
171
172void TargetMachine::setOptLevel(CodeGenOpt::Level Level) const {
173  if (CodeGenInfo)
174    CodeGenInfo->setOptLevel(Level);
175}
176
177bool TargetMachine::getAsmVerbosityDefault() {
178  return AsmVerbosityDefault;
179}
180
181void TargetMachine::setAsmVerbosityDefault(bool V) {
182  AsmVerbosityDefault = V;
183}
184
185bool TargetMachine::getFunctionSections() {
186  return FunctionSections;
187}
188
189bool TargetMachine::getDataSections() {
190  return DataSections;
191}
192
193void TargetMachine::setFunctionSections(bool V) {
194  FunctionSections = V;
195}
196
197void TargetMachine::setDataSections(bool V) {
198  DataSections = V;
199}
200
201void TargetMachine::getNameWithPrefix(SmallVectorImpl<char> &Name,
202                                      const GlobalValue *GV, Mangler &Mang,
203                                      bool MayAlwaysUsePrivate) const {
204  if (MayAlwaysUsePrivate || !GV->hasPrivateLinkage()) {
205    // Simple case: If GV is not private, it is not important to find out if
206    // private labels are legal in this case or not.
207    Mang.getNameWithPrefix(Name, GV, false);
208    return;
209  }
210  SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, *this);
211  const TargetLoweringObjectFile &TLOF =
212      getTargetLowering()->getObjFileLowering();
213  const MCSection *TheSection = TLOF.SectionForGlobal(GV, GVKind, Mang, *this);
214  bool CannotUsePrivateLabel = TLOF.isSectionAtomizableBySymbols(*TheSection);
215  Mang.getNameWithPrefix(Name, GV, CannotUsePrivateLabel);
216}
217
218MCSymbol *TargetMachine::getSymbol(const GlobalValue *GV, Mangler &Mang) const {
219  SmallString<60> NameStr;
220  getNameWithPrefix(NameStr, GV, Mang);
221  const TargetLoweringObjectFile &TLOF =
222      getTargetLowering()->getObjFileLowering();
223  return TLOF.getContext().GetOrCreateSymbol(NameStr.str());
224}
225