1//===-- XCoreLowerThreadLocal - Lower thread local variables --------------===// 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/// \file 11/// \brief This file contains a pass that lowers thread local variables on the 12/// XCore. 13/// 14//===----------------------------------------------------------------------===// 15 16#include "XCore.h" 17#include "llvm/IR/Constants.h" 18#include "llvm/IR/DerivedTypes.h" 19#include "llvm/IR/GlobalVariable.h" 20#include "llvm/IR/IRBuilder.h" 21#include "llvm/IR/Intrinsics.h" 22#include "llvm/IR/Module.h" 23#include "llvm/IR/NoFolder.h" 24#include "llvm/IR/ValueHandle.h" 25#include "llvm/Pass.h" 26#include "llvm/Support/CommandLine.h" 27#include "llvm/Transforms/Utils/BasicBlockUtils.h" 28 29#define DEBUG_TYPE "xcore-lower-thread-local" 30 31using namespace llvm; 32 33static cl::opt<unsigned> MaxThreads( 34 "xcore-max-threads", cl::Optional, 35 cl::desc("Maximum number of threads (for emulation thread-local storage)"), 36 cl::Hidden, cl::value_desc("number"), cl::init(8)); 37 38namespace { 39 /// Lowers thread local variables on the XCore. Each thread local variable is 40 /// expanded to an array of n elements indexed by the thread ID where n is the 41 /// fixed number hardware threads supported by the device. 42 struct XCoreLowerThreadLocal : public ModulePass { 43 static char ID; 44 45 XCoreLowerThreadLocal() : ModulePass(ID) { 46 initializeXCoreLowerThreadLocalPass(*PassRegistry::getPassRegistry()); 47 } 48 49 bool lowerGlobal(GlobalVariable *GV); 50 51 bool runOnModule(Module &M) override; 52 }; 53} 54 55char XCoreLowerThreadLocal::ID = 0; 56 57INITIALIZE_PASS(XCoreLowerThreadLocal, "xcore-lower-thread-local", 58 "Lower thread local variables", false, false) 59 60ModulePass *llvm::createXCoreLowerThreadLocalPass() { 61 return new XCoreLowerThreadLocal(); 62} 63 64static ArrayType *createLoweredType(Type *OriginalType) { 65 return ArrayType::get(OriginalType, MaxThreads); 66} 67 68static Constant * 69createLoweredInitializer(ArrayType *NewType, Constant *OriginalInitializer) { 70 SmallVector<Constant *, 8> Elements(MaxThreads); 71 for (unsigned i = 0; i != MaxThreads; ++i) { 72 Elements[i] = OriginalInitializer; 73 } 74 return ConstantArray::get(NewType, Elements); 75} 76 77static Instruction * 78createReplacementInstr(ConstantExpr *CE, Instruction *Instr) { 79 IRBuilder<true,NoFolder> Builder(Instr); 80 unsigned OpCode = CE->getOpcode(); 81 switch (OpCode) { 82 case Instruction::GetElementPtr: { 83 SmallVector<Value *,4> CEOpVec(CE->op_begin(), CE->op_end()); 84 ArrayRef<Value *> CEOps(CEOpVec); 85 return dyn_cast<Instruction>(Builder.CreateInBoundsGEP(CEOps[0], 86 CEOps.slice(1))); 87 } 88 case Instruction::Add: 89 case Instruction::Sub: 90 case Instruction::Mul: 91 case Instruction::UDiv: 92 case Instruction::SDiv: 93 case Instruction::FDiv: 94 case Instruction::URem: 95 case Instruction::SRem: 96 case Instruction::FRem: 97 case Instruction::Shl: 98 case Instruction::LShr: 99 case Instruction::AShr: 100 case Instruction::And: 101 case Instruction::Or: 102 case Instruction::Xor: 103 return dyn_cast<Instruction>( 104 Builder.CreateBinOp((Instruction::BinaryOps)OpCode, 105 CE->getOperand(0), CE->getOperand(1), 106 CE->getName())); 107 case Instruction::Trunc: 108 case Instruction::ZExt: 109 case Instruction::SExt: 110 case Instruction::FPToUI: 111 case Instruction::FPToSI: 112 case Instruction::UIToFP: 113 case Instruction::SIToFP: 114 case Instruction::FPTrunc: 115 case Instruction::FPExt: 116 case Instruction::PtrToInt: 117 case Instruction::IntToPtr: 118 case Instruction::BitCast: 119 return dyn_cast<Instruction>( 120 Builder.CreateCast((Instruction::CastOps)OpCode, 121 CE->getOperand(0), CE->getType(), 122 CE->getName())); 123 default: 124 llvm_unreachable("Unhandled constant expression!\n"); 125 } 126} 127 128static bool replaceConstantExprOp(ConstantExpr *CE, Pass *P) { 129 do { 130 SmallVector<WeakVH,8> WUsers(CE->user_begin(), CE->user_end()); 131 std::sort(WUsers.begin(), WUsers.end()); 132 WUsers.erase(std::unique(WUsers.begin(), WUsers.end()), WUsers.end()); 133 while (!WUsers.empty()) 134 if (WeakVH WU = WUsers.pop_back_val()) { 135 if (PHINode *PN = dyn_cast<PHINode>(WU)) { 136 for (int I = 0, E = PN->getNumIncomingValues(); I < E; ++I) 137 if (PN->getIncomingValue(I) == CE) { 138 BasicBlock *PredBB = PN->getIncomingBlock(I); 139 if (PredBB->getTerminator()->getNumSuccessors() > 1) 140 PredBB = SplitEdge(PredBB, PN->getParent(), P); 141 Instruction *InsertPos = PredBB->getTerminator(); 142 Instruction *NewInst = createReplacementInstr(CE, InsertPos); 143 PN->setOperand(I, NewInst); 144 } 145 } else if (Instruction *Instr = dyn_cast<Instruction>(WU)) { 146 Instruction *NewInst = createReplacementInstr(CE, Instr); 147 Instr->replaceUsesOfWith(CE, NewInst); 148 } else { 149 ConstantExpr *CExpr = dyn_cast<ConstantExpr>(WU); 150 if (!CExpr || !replaceConstantExprOp(CExpr, P)) 151 return false; 152 } 153 } 154 } while (CE->hasNUsesOrMore(1)); // We need to check because a recursive 155 // sibling may have used 'CE' when createReplacementInstr was called. 156 CE->destroyConstant(); 157 return true; 158} 159 160static bool rewriteNonInstructionUses(GlobalVariable *GV, Pass *P) { 161 SmallVector<WeakVH,8> WUsers; 162 for (User *U : GV->users()) 163 if (!isa<Instruction>(U)) 164 WUsers.push_back(WeakVH(U)); 165 while (!WUsers.empty()) 166 if (WeakVH WU = WUsers.pop_back_val()) { 167 ConstantExpr *CE = dyn_cast<ConstantExpr>(WU); 168 if (!CE || !replaceConstantExprOp(CE, P)) 169 return false; 170 } 171 return true; 172} 173 174static bool isZeroLengthArray(Type *Ty) { 175 ArrayType *AT = dyn_cast<ArrayType>(Ty); 176 return AT && (AT->getNumElements() == 0); 177} 178 179bool XCoreLowerThreadLocal::lowerGlobal(GlobalVariable *GV) { 180 Module *M = GV->getParent(); 181 LLVMContext &Ctx = M->getContext(); 182 if (!GV->isThreadLocal()) 183 return false; 184 185 // Skip globals that we can't lower and leave it for the backend to error. 186 if (!rewriteNonInstructionUses(GV, this) || 187 !GV->getType()->isSized() || isZeroLengthArray(GV->getType())) 188 return false; 189 190 // Create replacement global. 191 ArrayType *NewType = createLoweredType(GV->getType()->getElementType()); 192 Constant *NewInitializer = nullptr; 193 if (GV->hasInitializer()) 194 NewInitializer = createLoweredInitializer(NewType, 195 GV->getInitializer()); 196 GlobalVariable *NewGV = 197 new GlobalVariable(*M, NewType, GV->isConstant(), GV->getLinkage(), 198 NewInitializer, "", nullptr, 199 GlobalVariable::NotThreadLocal, 200 GV->getType()->getAddressSpace(), 201 GV->isExternallyInitialized()); 202 203 // Update uses. 204 SmallVector<User *, 16> Users(GV->user_begin(), GV->user_end()); 205 for (unsigned I = 0, E = Users.size(); I != E; ++I) { 206 User *U = Users[I]; 207 Instruction *Inst = cast<Instruction>(U); 208 IRBuilder<> Builder(Inst); 209 Function *GetID = Intrinsic::getDeclaration(GV->getParent(), 210 Intrinsic::xcore_getid); 211 Value *ThreadID = Builder.CreateCall(GetID); 212 SmallVector<Value *, 2> Indices; 213 Indices.push_back(Constant::getNullValue(Type::getInt64Ty(Ctx))); 214 Indices.push_back(ThreadID); 215 Value *Addr = Builder.CreateInBoundsGEP(NewGV, Indices); 216 U->replaceUsesOfWith(GV, Addr); 217 } 218 219 // Remove old global. 220 NewGV->takeName(GV); 221 GV->eraseFromParent(); 222 return true; 223} 224 225bool XCoreLowerThreadLocal::runOnModule(Module &M) { 226 // Find thread local globals. 227 bool MadeChange = false; 228 SmallVector<GlobalVariable *, 16> ThreadLocalGlobals; 229 for (Module::global_iterator GVI = M.global_begin(), E = M.global_end(); 230 GVI != E; ++GVI) { 231 GlobalVariable *GV = GVI; 232 if (GV->isThreadLocal()) 233 ThreadLocalGlobals.push_back(GV); 234 } 235 for (unsigned I = 0, E = ThreadLocalGlobals.size(); I != E; ++I) { 236 MadeChange |= lowerGlobal(ThreadLocalGlobals[I]); 237 } 238 return MadeChange; 239} 240