180 lines · cpp
1//===-- XCoreLowerThreadLocal - Lower thread local variables --------------===//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-exception6//7//===----------------------------------------------------------------------===//8///9/// \file10/// This file contains a pass that lowers thread local variables on the11/// XCore.12///13//===----------------------------------------------------------------------===//14 15#include "XCore.h"16#include "llvm/IR/Constants.h"17#include "llvm/IR/DerivedTypes.h"18#include "llvm/IR/GlobalVariable.h"19#include "llvm/IR/IRBuilder.h"20#include "llvm/IR/Intrinsics.h"21#include "llvm/IR/IntrinsicsXCore.h"22#include "llvm/IR/Module.h"23#include "llvm/IR/ValueHandle.h"24#include "llvm/Pass.h"25#include "llvm/Support/CommandLine.h"26#include "llvm/Transforms/Utils/BasicBlockUtils.h"27 28#define DEBUG_TYPE "xcore-lower-thread-local"29 30using namespace llvm;31 32static cl::opt<unsigned> MaxThreads(33 "xcore-max-threads", cl::Optional,34 cl::desc("Maximum number of threads (for emulation thread-local storage)"),35 cl::Hidden, cl::value_desc("number"), cl::init(8));36 37namespace {38 /// Lowers thread local variables on the XCore. Each thread local variable is39 /// expanded to an array of n elements indexed by the thread ID where n is the40 /// fixed number hardware threads supported by the device.41 struct XCoreLowerThreadLocal : public ModulePass {42 static char ID;43 44 XCoreLowerThreadLocal() : ModulePass(ID) {}45 46 bool lowerGlobal(GlobalVariable *GV);47 48 bool runOnModule(Module &M) override;49 };50}51 52char XCoreLowerThreadLocal::ID = 0;53 54INITIALIZE_PASS(XCoreLowerThreadLocal, "xcore-lower-thread-local",55 "Lower thread local variables", false, false)56 57ModulePass *llvm::createXCoreLowerThreadLocalPass() {58 return new XCoreLowerThreadLocal();59}60 61static ArrayType *createLoweredType(Type *OriginalType) {62 return ArrayType::get(OriginalType, MaxThreads);63}64 65static Constant *66createLoweredInitializer(ArrayType *NewType, Constant *OriginalInitializer) {67 SmallVector<Constant *, 8> Elements(MaxThreads);68 for (unsigned i = 0; i != MaxThreads; ++i) {69 Elements[i] = OriginalInitializer;70 }71 return ConstantArray::get(NewType, Elements);72}73 74 75static bool replaceConstantExprOp(ConstantExpr *CE, Pass *P) {76 do {77 SmallVector<WeakTrackingVH, 8> WUsers(CE->users());78 llvm::sort(WUsers);79 WUsers.erase(llvm::unique(WUsers), WUsers.end());80 while (!WUsers.empty())81 if (WeakTrackingVH WU = WUsers.pop_back_val()) {82 if (PHINode *PN = dyn_cast<PHINode>(WU)) {83 for (int I = 0, E = PN->getNumIncomingValues(); I < E; ++I)84 if (PN->getIncomingValue(I) == CE) {85 BasicBlock *PredBB = PN->getIncomingBlock(I);86 if (PredBB->getTerminator()->getNumSuccessors() > 1)87 PredBB = SplitEdge(PredBB, PN->getParent());88 BasicBlock::iterator InsertPos =89 PredBB->getTerminator()->getIterator();90 Instruction *NewInst = CE->getAsInstruction();91 NewInst->insertBefore(*PredBB, InsertPos);92 PN->setOperand(I, NewInst);93 }94 } else if (Instruction *Instr = dyn_cast<Instruction>(WU)) {95 Instruction *NewInst = CE->getAsInstruction();96 NewInst->insertBefore(*Instr->getParent(), Instr->getIterator());97 Instr->replaceUsesOfWith(CE, NewInst);98 } else {99 ConstantExpr *CExpr = dyn_cast<ConstantExpr>(WU);100 if (!CExpr || !replaceConstantExprOp(CExpr, P))101 return false;102 }103 }104 } while (CE->hasNUsesOrMore(1)); // We need to check because a recursive105 // sibling may have used 'CE' when getAsInstruction was called.106 CE->destroyConstant();107 return true;108}109 110static bool rewriteNonInstructionUses(GlobalVariable *GV, Pass *P) {111 SmallVector<WeakTrackingVH, 8> WUsers;112 for (User *U : GV->users())113 if (!isa<Instruction>(U))114 WUsers.push_back(WeakTrackingVH(U));115 while (!WUsers.empty())116 if (WeakTrackingVH WU = WUsers.pop_back_val()) {117 ConstantExpr *CE = dyn_cast<ConstantExpr>(WU);118 if (!CE || !replaceConstantExprOp(CE, P))119 return false;120 }121 return true;122}123 124static bool isZeroLengthArray(Type *Ty) {125 ArrayType *AT = dyn_cast<ArrayType>(Ty);126 return AT && (AT->getNumElements() == 0);127}128 129bool XCoreLowerThreadLocal::lowerGlobal(GlobalVariable *GV) {130 Module *M = GV->getParent();131 if (!GV->isThreadLocal())132 return false;133 134 // Skip globals that we can't lower and leave it for the backend to error.135 if (!rewriteNonInstructionUses(GV, this) ||136 !GV->getType()->isSized() || isZeroLengthArray(GV->getType()))137 return false;138 139 // Create replacement global.140 ArrayType *NewType = createLoweredType(GV->getValueType());141 Constant *NewInitializer = nullptr;142 if (GV->hasInitializer())143 NewInitializer = createLoweredInitializer(NewType,144 GV->getInitializer());145 GlobalVariable *NewGV =146 new GlobalVariable(*M, NewType, GV->isConstant(), GV->getLinkage(),147 NewInitializer, "", nullptr,148 GlobalVariable::NotThreadLocal,149 GV->getType()->getAddressSpace(),150 GV->isExternallyInitialized());151 152 // Update uses.153 SmallVector<User *, 16> Users(GV->users());154 for (User *U : Users) {155 Instruction *Inst = cast<Instruction>(U);156 IRBuilder<> Builder(Inst);157 Value *ThreadID = Builder.CreateIntrinsic(Intrinsic::xcore_getid, {});158 Value *Addr = Builder.CreateInBoundsGEP(NewGV->getValueType(), NewGV,159 {Builder.getInt64(0), ThreadID});160 U->replaceUsesOfWith(GV, Addr);161 }162 163 // Remove old global.164 NewGV->takeName(GV);165 GV->eraseFromParent();166 return true;167}168 169bool XCoreLowerThreadLocal::runOnModule(Module &M) {170 // Find thread local globals.171 bool MadeChange = false;172 SmallVector<GlobalVariable *, 16> ThreadLocalGlobals;173 for (GlobalVariable &GV : M.globals())174 if (GV.isThreadLocal())175 ThreadLocalGlobals.push_back(&GV);176 for (GlobalVariable *GV : ThreadLocalGlobals)177 MadeChange |= lowerGlobal(GV);178 return MadeChange;179}180