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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}