LLVM 19.0.0git
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1//===- LowerEmuTLS.cpp - Add __emutls_[vt].* variables --------------------===//
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
9// This transformation is required for targets depending on libgcc style
10// emulated thread local storage variables. For every defined TLS variable xyz,
11// an __emutls_v.xyz is generated. If there is non-zero initialized value
12// an __emutls_t.xyz is also generated.
21#include "llvm/CodeGen/Passes.h"
23#include "llvm/IR/Constants.h"
24#include "llvm/IR/Module.h"
26#include "llvm/Pass.h"
29using namespace llvm;
31#define DEBUG_TYPE "lower-emutls"
33namespace {
35class LowerEmuTLS : public ModulePass {
37 static char ID; // Pass identification, replacement for typeid
38 LowerEmuTLS() : ModulePass(ID) {
40 }
42 bool runOnModule(Module &M) override;
46static bool addEmuTlsVar(Module &M, const GlobalVariable *GV);
48static void copyLinkageVisibility(Module &M, const GlobalVariable *from,
49 GlobalVariable *to) {
50 to->setLinkage(from->getLinkage());
51 to->setVisibility(from->getVisibility());
52 to->setDSOLocal(from->isDSOLocal());
53 if (from->hasComdat()) {
54 to->setComdat(M.getOrInsertComdat(to->getName()));
56 }
60 bool Changed = false;
62 for (const auto &G : M.globals()) {
63 if (G.isThreadLocal())
64 TlsVars.push_back(&G);
65 }
66 for (const auto *G : TlsVars)
67 Changed |= addEmuTlsVar(M, G);
69 if (!Changed)
72 PA.abandon<GlobalsAA>();
75 return PA;
78char LowerEmuTLS::ID = 0;
81 "Add __emutls_[vt]. variables for emultated TLS model", false,
82 false)
84ModulePass *llvm::createLowerEmuTLSPass() { return new LowerEmuTLS(); }
86bool LowerEmuTLS::runOnModule(Module &M) {
87 if (skipModule(M))
88 return false;
90 auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
91 if (!TPC)
92 return false;
94 auto &TM = TPC->getTM<TargetMachine>();
95 if (!TM.useEmulatedTLS())
96 return false;
98 bool Changed = false;
100 for (const auto &G : M.globals()) {
101 if (G.isThreadLocal())
102 TlsVars.append({&G});
103 }
104 for (const auto *const G : TlsVars)
105 Changed |= addEmuTlsVar(M, G);
106 return Changed;
109bool addEmuTlsVar(Module &M, const GlobalVariable *GV) {
110 LLVMContext &C = M.getContext();
111 PointerType *VoidPtrType = PointerType::getUnqual(C);
113 std::string EmuTlsVarName = ("__emutls_v." + GV->getName()).str();
114 GlobalVariable *EmuTlsVar = M.getNamedGlobal(EmuTlsVarName);
115 if (EmuTlsVar)
116 return false; // It has been added before.
118 const DataLayout &DL = M.getDataLayout();
119 Constant *NullPtr = ConstantPointerNull::get(VoidPtrType);
121 // Get non-zero initializer from GV's initializer.
122 const Constant *InitValue = nullptr;
123 if (GV->hasInitializer()) {
124 InitValue = GV->getInitializer();
125 const ConstantInt *InitIntValue = dyn_cast<ConstantInt>(InitValue);
126 // When GV's init value is all 0, omit the EmuTlsTmplVar and let
127 // the emutls library function to reset newly allocated TLS variables.
128 if (isa<ConstantAggregateZero>(InitValue) ||
129 (InitIntValue && InitIntValue->isZero()))
130 InitValue = nullptr;
131 }
133 // Create the __emutls_v. symbol, whose type has 4 fields:
134 // word size; // size of GV in bytes
135 // word align; // alignment of GV
136 // void *ptr; // initialized to 0; set at run time per thread.
137 // void *templ; // 0 or point to __emutls_t.*
138 // sizeof(word) should be the same as sizeof(void*) on target.
139 IntegerType *WordType = DL.getIntPtrType(C);
140 PointerType *InitPtrType = PointerType::getUnqual(C);
141 Type *ElementTypes[4] = {WordType, WordType, VoidPtrType, InitPtrType};
142 StructType *EmuTlsVarType = StructType::create(ElementTypes);
143 EmuTlsVar = cast<GlobalVariable>(
144 M.getOrInsertGlobal(EmuTlsVarName, EmuTlsVarType));
145 copyLinkageVisibility(M, GV, EmuTlsVar);
147 // Define "__emutls_t.*" and "__emutls_v.*" only if GV is defined.
148 if (!GV->hasInitializer())
149 return true;
151 Type *GVType = GV->getValueType();
152 Align GVAlignment = DL.getValueOrABITypeAlignment(GV->getAlign(), GVType);
154 // Define "__emutls_t.*" if there is InitValue
155 GlobalVariable *EmuTlsTmplVar = nullptr;
156 if (InitValue) {
157 std::string EmuTlsTmplName = ("__emutls_t." + GV->getName()).str();
158 EmuTlsTmplVar = dyn_cast_or_null<GlobalVariable>(
159 M.getOrInsertGlobal(EmuTlsTmplName, GVType));
160 assert(EmuTlsTmplVar && "Failed to create emualted TLS initializer");
161 EmuTlsTmplVar->setConstant(true);
162 EmuTlsTmplVar->setInitializer(const_cast<Constant*>(InitValue));
163 EmuTlsTmplVar->setAlignment(GVAlignment);
164 copyLinkageVisibility(M, GV, EmuTlsTmplVar);
165 }
167 // Define "__emutls_v.*" with initializer and alignment.
168 Constant *ElementValues[4] = {
169 ConstantInt::get(WordType, DL.getTypeStoreSize(GVType)),
170 ConstantInt::get(WordType, GVAlignment.value()), NullPtr,
171 EmuTlsTmplVar ? EmuTlsTmplVar : NullPtr};
172 EmuTlsVar->setInitializer(ConstantStruct::get(EmuTlsVarType, ElementValues));
173 Align MaxAlignment =
174 std::max(DL.getABITypeAlign(WordType), DL.getABITypeAlign(VoidPtrType));
175 EmuTlsVar->setAlignment(MaxAlignment);
176 return true;
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
This file contains the declarations for the subclasses of Constant, which represent the different fla...
#define DEBUG_TYPE
This is the interface for a simple mod/ref and alias analysis over globals.
static void copyLinkageVisibility(Module &M, const GlobalVariable *from, GlobalVariable *to)
Definition: LowerEmuTLS.cpp:48
static bool addEmuTlsVar(Module &M, const GlobalVariable *GV)
#define G(x, y, z)
Definition: MD5.cpp:56
This is the interface to build a ModuleSummaryIndex for a module.
Module.h This file contains the declarations for the Module class.
ModuleAnalysisManager MAM
const char LLVMTargetMachineRef TM
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:38
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This file defines the SmallVector class.
Target-Independent Code Generator Pass Configuration Options pass.
A container for analyses that lazily runs them and caches their results.
Definition: PassManager.h:253
void setSelectionKind(SelectionKind Val)
Definition: Comdat.h:47
SelectionKind getSelectionKind() const
Definition: Comdat.h:46
This is the shared class of boolean and integer constants.
Definition: Constants.h:81
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:206
static ConstantPointerNull * get(PointerType *T)
Static factory methods - Return objects of the specified value.
Definition: Constants.cpp:1800
static Constant * get(StructType *T, ArrayRef< Constant * > V)
Definition: Constants.cpp:1357
This is an important base class in LLVM.
Definition: Constant.h:42
A parsed version of the target data layout string in and methods for querying it.
Definition: DataLayout.h:110
MaybeAlign getAlign() const
Returns the alignment of the given variable or function.
Definition: GlobalObject.h:80
void setAlignment(Align Align)
Sets the alignment attribute of the GlobalObject.
Definition: Globals.cpp:137
void setComdat(Comdat *C)
Definition: Globals.cpp:206
bool hasComdat() const
Definition: GlobalObject.h:128
const Comdat * getComdat() const
Definition: GlobalObject.h:129
bool isDSOLocal() const
Definition: GlobalValue.h:305
VisibilityTypes getVisibility() const
Definition: GlobalValue.h:248
LinkageTypes getLinkage() const
Definition: GlobalValue.h:546
void setLinkage(LinkageTypes LT)
Definition: GlobalValue.h:537
void setDSOLocal(bool Local)
Definition: GlobalValue.h:303
void setVisibility(VisibilityTypes V)
Definition: GlobalValue.h:254
Type * getValueType() const
Definition: GlobalValue.h:296
const Constant * getInitializer() const
getInitializer - Return the initializer for this global variable.
void setInitializer(Constant *InitVal)
setInitializer - Sets the initializer for this global variable, removing any existing initializer if ...
Definition: Globals.cpp:485
bool hasInitializer() const
Definitions have initializers, declarations don't.
void setConstant(bool Val)
Analysis pass providing a never-invalidated alias analysis result.
Class to represent integer types.
Definition: DerivedTypes.h:40
This is an important class for using LLVM in a threaded context.
Definition: LLVMContext.h:67
PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM)
Definition: LowerEmuTLS.cpp:59
ModulePass class - This class is used to implement unstructured interprocedural optimizations and ana...
Definition: Pass.h:251
virtual bool runOnModule(Module &M)=0
runOnModule - Virtual method overriden by subclasses to process the module being operated on.
Analysis pass to provide the ModuleSummaryIndex object.
A Module instance is used to store all the information related to an LLVM module.
Definition: Module.h:65
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
static PointerType * getUnqual(Type *ElementType)
This constructs a pointer to an object of the specified type in the default address space (address sp...
Definition: DerivedTypes.h:662
A set of analyses that are preserved following a run of a transformation pass.
Definition: Analysis.h:111
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: Analysis.h:117
void abandon()
Mark an analysis as abandoned.
Definition: Analysis.h:164
void append(ItTy in_start, ItTy in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:696
void push_back(const T &Elt)
Definition: SmallVector.h:426
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1209
This pass performs the global (interprocedural) stack safety analysis (new pass manager).
Class to represent struct types.
Definition: DerivedTypes.h:216
static StructType * create(LLVMContext &Context, StringRef Name)
This creates an identified struct.
Definition: Type.cpp:513
Primary interface to the complete machine description for the target machine.
Definition: TargetMachine.h:77
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:309
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
Definition: CallingConv.h:24
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
ModulePass * createLowerEmuTLSPass()
LowerEmuTLS - This pass generates __emutls_[vt].xyz variables for all TLS variables for the emulated ...
void initializeLowerEmuTLSPass(PassRegistry &)
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:39
uint64_t value() const
This is a hole in the type system and should not be abused.
Definition: Alignment.h:85