LLVM  16.0.0git
TargetMachine.cpp
Go to the documentation of this file.
1 //===-- TargetMachine.cpp - General Target Information ---------------------==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file describes the general parts of a Target machine.
10 //
11 //===----------------------------------------------------------------------===//
12 
15 #include "llvm/IR/Function.h"
16 #include "llvm/IR/GlobalValue.h"
17 #include "llvm/IR/GlobalVariable.h"
18 #include "llvm/IR/Mangler.h"
19 #include "llvm/MC/MCAsmInfo.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCInstrInfo.h"
22 #include "llvm/MC/MCRegisterInfo.h"
25 using namespace llvm;
26 
27 //---------------------------------------------------------------------------
28 // TargetMachine Class
29 //
30 
32  const Triple &TT, StringRef CPU, StringRef FS,
33  const TargetOptions &Options)
34  : TheTarget(T), DL(DataLayoutString), TargetTriple(TT),
35  TargetCPU(std::string(CPU)), TargetFS(std::string(FS)), AsmInfo(nullptr),
36  MRI(nullptr), MII(nullptr), STI(nullptr), RequireStructuredCFG(false),
37  O0WantsFastISel(false), DefaultOptions(Options), Options(Options) {}
38 
40 
42  return getRelocationModel() == Reloc::PIC_;
43 }
44 
45 /// Reset the target options based on the function's attributes.
46 /// setFunctionAttributes should have made the raw attribute value consistent
47 /// with the command line flag if used.
48 //
49 // FIXME: This function needs to go away for a number of reasons:
50 // a) global state on the TargetMachine is terrible in general,
51 // b) these target options should be passed only on the function
52 // and not on the TargetMachine (via TargetOptions) at all.
54 #define RESET_OPTION(X, Y) \
55  do { \
56  Options.X = F.getFnAttribute(Y).getValueAsBool(); \
57  } while (0)
58 
59  RESET_OPTION(UnsafeFPMath, "unsafe-fp-math");
60  RESET_OPTION(NoInfsFPMath, "no-infs-fp-math");
61  RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math");
62  RESET_OPTION(NoSignedZerosFPMath, "no-signed-zeros-fp-math");
63  RESET_OPTION(ApproxFuncFPMath, "approx-func-fp-math");
64 }
65 
66 /// Returns the code generation relocation model. The choices are static, PIC,
67 /// and dynamic-no-pic.
69 
70 /// Get the IR-specified TLS model for Var.
72  switch (GV->getThreadLocalMode()) {
74  llvm_unreachable("getSelectedTLSModel for non-TLS variable");
75  break;
81  return TLSModel::InitialExec;
83  return TLSModel::LocalExec;
84  }
85  llvm_unreachable("invalid TLS model");
86 }
87 
89  const GlobalValue *GV) const {
90  const Triple &TT = getTargetTriple();
92 
93  // According to the llvm language reference, we should be able to
94  // just return false in here if we have a GV, as we know it is
95  // dso_preemptable. At this point in time, the various IR producers
96  // have not been transitioned to always produce a dso_local when it
97  // is possible to do so.
98  //
99  // As a result we still have some logic in here to improve the quality of the
100  // generated code.
101  if (!GV)
102  return false;
103 
104  // If the IR producer requested that this GV be treated as dso local, obey.
105  if (GV->isDSOLocal())
106  return true;
107 
108  if (TT.isOSBinFormatCOFF()) {
109  // DLLImport explicitly marks the GV as external.
110  if (GV->hasDLLImportStorageClass())
111  return false;
112 
113  // On MinGW, variables that haven't been declared with DLLImport may still
114  // end up automatically imported by the linker. To make this feasible,
115  // don't assume the variables to be DSO local unless we actually know
116  // that for sure. This only has to be done for variables; for functions
117  // the linker can insert thunks for calling functions from another DLL.
118  if (TT.isWindowsGNUEnvironment() && GV->isDeclarationForLinker() &&
119  isa<GlobalVariable>(GV))
120  return false;
121 
122  // Don't mark 'extern_weak' symbols as DSO local. If these symbols remain
123  // unresolved in the link, they can be resolved to zero, which is outside
124  // the current DSO.
125  if (GV->hasExternalWeakLinkage())
126  return false;
127 
128  // Every other GV is local on COFF.
129  return true;
130  }
131 
132  if (TT.isOSBinFormatGOFF())
133  return true;
134 
135  if (TT.isOSBinFormatMachO()) {
136  if (RM == Reloc::Static)
137  return true;
138  return GV->isStrongDefinitionForLinker();
139  }
140 
141  assert(TT.isOSBinFormatELF() || TT.isOSBinFormatWasm() ||
142  TT.isOSBinFormatXCOFF());
143  return false;
144 }
145 
147  // Returns Options.EmulatedTLS if the -emulated-tls or -no-emulated-tls
148  // was specified explicitly; otherwise uses target triple to decide default.
150  return Options.EmulatedTLS;
152 }
153 
155  bool IsPIE = GV->getParent()->getPIELevel() != PIELevel::Default;
157  bool IsSharedLibrary = RM == Reloc::PIC_ && !IsPIE;
158  bool IsLocal = shouldAssumeDSOLocal(*GV->getParent(), GV);
159 
161  if (IsSharedLibrary) {
162  if (IsLocal)
164  else
166  } else {
167  if (IsLocal)
169  else
171  }
172 
173  // If the user specified a more specific model, use that.
174  TLSModel::Model SelectedModel = getSelectedTLSModel(GV);
175  if (SelectedModel > Model)
176  return SelectedModel;
177 
178  return Model;
179 }
180 
181 /// Returns the optimization level: None, Less, Default, or Aggressive.
183 
185 
188  return TargetTransformInfo(F.getParent()->getDataLayout());
189 }
190 
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  }
201  TLOF->getNameWithPrefix(Name, GV, *this);
202 }
203 
206  // XCOFF symbols could have special naming convention.
207  if (MCSymbol *TargetSymbol = TLOF->getTargetSymbol(GV, *this))
208  return TargetSymbol;
209 
210  SmallString<128> NameStr;
211  getNameWithPrefix(NameStr, GV, TLOF->getMangler());
212  return TLOF->getContext().getOrCreateSymbol(NameStr);
213 }
214 
216  // Since Analysis can't depend on Target, use a std::function to invert the
217  // dependency.
218  return TargetIRAnalysis(
219  [this](const Function &F) { return this->getTargetTransformInfo(F); });
220 }
221 
223  if (Version == "none")
224  return {INT_MAX, INT_MAX}; // Make binutilsIsAtLeast() return true.
225  std::pair<int, int> Ret;
226  if (!Version.consumeInteger(10, Ret.first) && Version.consume_front("."))
227  Version.consumeInteger(10, Ret.second);
228  return Ret;
229 }
llvm::TargetMachine::getOptLevel
CodeGenOpt::Level getOptLevel() const
Returns the optimization level: None, Less, Default, or Aggressive.
Definition: TargetMachine.cpp:182
llvm::TargetIRAnalysis
Analysis pass providing the TargetTransformInfo.
Definition: TargetTransformInfo.h:2592
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
llvm::MCSymbol
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
llvm::TargetMachine::useEmulatedTLS
bool useEmulatedTLS() const
Returns true if this target uses emulated TLS.
Definition: TargetMachine.cpp:146
llvm::TargetLoweringObjectFile::getNameWithPrefix
virtual void getNameWithPrefix(SmallVectorImpl< char > &OutName, const GlobalValue *GV, const TargetMachine &TM) const
Definition: TargetLoweringObjectFile.cpp:438
llvm::TargetOptions
Definition: TargetOptions.h:124
llvm::GlobalValue::LocalDynamicTLSModel
@ LocalDynamicTLSModel
Definition: GlobalValue.h:194
T
llvm::Function
Definition: Function.h:60
llvm::Target
Target - Wrapper for Target specific information.
Definition: TargetRegistry.h:150
llvm::TLSModel::GeneralDynamic
@ GeneralDynamic
Definition: CodeGen.h:43
llvm::GlobalValue::NotThreadLocal
@ NotThreadLocal
Definition: GlobalValue.h:192
llvm::TargetTransformInfo
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
Definition: TargetTransformInfo.h:173
RESET_OPTION
#define RESET_OPTION(X, Y)
llvm::Triple
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
getSelectedTLSModel
static TLSModel::Model getSelectedTLSModel(const GlobalValue *GV)
Get the IR-specified TLS model for Var.
Definition: TargetMachine.cpp:71
llvm::TargetMachine::getRelocationModel
Reloc::Model getRelocationModel() const
Returns the code generation relocation model.
Definition: TargetMachine.cpp:68
llvm::TargetMachine::RM
Reloc::Model RM
Definition: TargetMachine.h:99
llvm::Triple::hasDefaultEmulatedTLS
bool hasDefaultEmulatedTLS() const
Tests whether the target uses emulated TLS as default.
Definition: Triple.h:948
llvm::MipsISD::Ret
@ Ret
Definition: MipsISelLowering.h:119
llvm::Mangler
Definition: Mangler.h:27
llvm::MCObjectFileInfo::getContext
MCContext & getContext() const
Definition: MCObjectFileInfo.h:244
llvm::TargetLoweringObjectFile::getTargetSymbol
virtual MCSymbol * getTargetSymbol(const GlobalValue *GV, const TargetMachine &TM) const
Targets that have a special convention for their symbols could use this hook to return a specialized ...
Definition: TargetLoweringObjectFile.h:274
llvm::GlobalValue::hasExternalWeakLinkage
bool hasExternalWeakLinkage() const
Definition: GlobalValue.h:524
F
#define F(x, y, z)
Definition: MD5.cpp:55
llvm::Reloc::Model
Model
Definition: CodeGen.h:22
llvm::TargetLoweringObjectFile
Definition: TargetLoweringObjectFile.h:45
llvm::MCContext::getOrCreateSymbol
MCSymbol * getOrCreateSymbol(const Twine &Name)
Lookup the symbol inside with the specified Name.
Definition: MCContext.cpp:201
GlobalValue.h
TargetMachine.h
llvm::GlobalValue::getThreadLocalMode
ThreadLocalMode getThreadLocalMode() const
Definition: GlobalValue.h:267
MCContext.h
MCInstrInfo.h
llvm::TargetMachine::parseBinutilsVersion
static std::pair< int, int > parseBinutilsVersion(StringRef Version)
Definition: TargetMachine.cpp:222
llvm::GlobalValue::hasPrivateLinkage
bool hasPrivateLinkage() const
Definition: GlobalValue.h:522
false
Definition: StackSlotColoring.cpp:141
llvm::Mangler::getNameWithPrefix
void getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV, bool CannotUsePrivateLabel) const
Print the appropriate prefix and the specified global variable's name.
Definition: Mangler.cpp:119
MCSubtargetInfo.h
Options
const char LLVMTargetMachineRef LLVMPassBuilderOptionsRef Options
Definition: PassBuilderBindings.cpp:48
llvm::IndexedInstrProf::Version
const uint64_t Version
Definition: InstrProf.h:1056
llvm::TargetOptions::EmulatedTLS
unsigned EmulatedTLS
EmulatedTLS - This flag enables emulated TLS model, using emutls function in the runtime library.
Definition: TargetOptions.h:291
llvm::TargetMachine::getSymbol
MCSymbol * getSymbol(const GlobalValue *GV) const
Definition: TargetMachine.cpp:204
llvm::TargetMachine::resetTargetOptions
void resetTargetOptions(const Function &F) const
Reset the target options based on the function's attributes.
Definition: TargetMachine.cpp:53
llvm::SmallString< 128 >
llvm::TargetMachine::isPositionIndependent
bool isPositionIndependent() const
Definition: TargetMachine.cpp:41
llvm::GlobalValue
Definition: GlobalValue.h:44
llvm::TLSModel::LocalDynamic
@ LocalDynamic
Definition: CodeGen.h:44
llvm::GlobalValue::getParent
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:652
llvm::GlobalValue::GeneralDynamicTLSModel
@ GeneralDynamicTLSModel
Definition: GlobalValue.h:193
llvm::TargetMachine::OptLevel
CodeGenOpt::Level OptLevel
Definition: TargetMachine.h:101
MCRegisterInfo.h
llvm::TargetMachine::getTargetIRAnalysis
TargetIRAnalysis getTargetIRAnalysis() const
Get a TargetIRAnalysis appropriate for the target.
Definition: TargetMachine.cpp:215
llvm::TargetMachine::getTLSModel
TLSModel::Model getTLSModel(const GlobalValue *GV) const
Returns the TLS model which should be used for the given global variable.
Definition: TargetMachine.cpp:154
llvm::TargetMachine::Options
TargetOptions Options
Definition: TargetMachine.h:117
llvm::TargetMachine::TargetMachine
TargetMachine(const Target &T, StringRef DataLayoutString, const Triple &TargetTriple, StringRef CPU, StringRef FS, const TargetOptions &Options)
Definition: TargetMachine.cpp:31
assert
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
llvm::X86AS::FS
@ FS
Definition: X86.h:200
llvm::TargetMachine::getObjFileLowering
virtual TargetLoweringObjectFile * getObjFileLowering() const
Definition: TargetMachine.h:135
llvm::Module
A Module instance is used to store all the information related to an LLVM module.
Definition: Module.h:65
Mangler.h
llvm::TargetLoweringObjectFile::getMangler
Mangler & getMangler() const
Definition: TargetLoweringObjectFile.h:77
MCAsmInfo.h
llvm::Reloc::PIC_
@ PIC_
Definition: CodeGen.h:22
llvm::PIELevel::Default
@ Default
Definition: CodeGen.h:37
llvm::StringRef
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
llvm_unreachable
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:143
TargetLoweringObjectFile.h
llvm::Reloc::Static
@ Static
Definition: CodeGen.h:22
DL
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
Definition: AArch64SLSHardening.cpp:76
llvm::TargetMachine::shouldAssumeDSOLocal
bool shouldAssumeDSOLocal(const Module &M, const GlobalValue *GV) const
Definition: TargetMachine.cpp:88
llvm::CodeGenOpt::Level
Level
Definition: CodeGen.h:52
llvm::GlobalValue::isStrongDefinitionForLinker
bool isStrongDefinitionForLinker() const
Returns true if this global's definition will be the one chosen by the linker.
Definition: GlobalValue.h:627
llvm::GlobalValue::LocalExecTLSModel
@ LocalExecTLSModel
Definition: GlobalValue.h:196
MRI
unsigned const MachineRegisterInfo * MRI
Definition: AArch64AdvSIMDScalarPass.cpp:105
std
Definition: BitVector.h:851
llvm::TargetMachine::getNameWithPrefix
void getNameWithPrefix(SmallVectorImpl< char > &Name, const GlobalValue *GV, Mangler &Mang, bool MayAlwaysUsePrivate=false) const
Definition: TargetMachine.cpp:191
GlobalVariable.h
Function.h
llvm::TLSModel::Model
Model
Definition: CodeGen.h:42
llvm::Module::getPIELevel
PIELevel::Level getPIELevel() const
Returns the PIE level (small or large model)
Definition: Module.cpp:604
llvm::TLSModel::InitialExec
@ InitialExec
Definition: CodeGen.h:45
llvm::TargetMachine::~TargetMachine
virtual ~TargetMachine()
llvm::TargetMachine::getTargetTriple
const Triple & getTargetTriple() const
Definition: TargetMachine.h:125
TargetTransformInfo.h
llvm::GlobalValue::isDeclarationForLinker
bool isDeclarationForLinker() const
Definition: GlobalValue.h:614
llvm::GlobalValue::hasDLLImportStorageClass
bool hasDLLImportStorageClass() const
Definition: GlobalValue.h:274
llvm::SmallVectorImpl< char >
llvm::TargetMachine::setOptLevel
void setOptLevel(CodeGenOpt::Level Level)
Overrides the optimization level.
Definition: TargetMachine.cpp:184
llvm::TargetMachine::getTargetTransformInfo
virtual TargetTransformInfo getTargetTransformInfo(const Function &F) const
Return a TargetTransformInfo for a given function.
Definition: TargetMachine.cpp:187
llvm::GlobalValue::InitialExecTLSModel
@ InitialExecTLSModel
Definition: GlobalValue.h:195
llvm::GlobalValue::isDSOLocal
bool isDSOLocal() const
Definition: GlobalValue.h:301
llvm::TargetOptions::ExplicitEmulatedTLS
unsigned ExplicitEmulatedTLS
Whether -emulated-tls or -no-emulated-tls is set.
Definition: TargetOptions.h:294
SpecialSubKind::string
@ string
llvm::TLSModel::LocalExec
@ LocalExec
Definition: CodeGen.h:46