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Thread local storage is not supported by the XMOS linker so we handle thread local variables by lowering the variable to an array of n elements (where n is the number of hardware threads per core, currently 8 for all XMOS devices) indexed by the the current thread ID. Previously this lowering was spread across the XCoreISelLowering and the XCoreAsmPrinter classes. Moving this to a separate pass should be much cleaner. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181124 91177308-0d34-0410-b5e6-96231b3b80d8
146 lines
4.7 KiB
C++
146 lines
4.7 KiB
C++
//===-- XCoreLowerThreadLocal - Lower thread local variables --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// \brief This file contains a pass that lowers thread local variables on the
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/// XCore.
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///
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//===----------------------------------------------------------------------===//
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#include "XCore.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/IR/Intrinsics.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CommandLine.h"
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#define DEBUG_TYPE "xcore-lower-thread-local"
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using namespace llvm;
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static cl::opt<unsigned> MaxThreads(
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"xcore-max-threads", cl::Optional,
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cl::desc("Maximum number of threads (for emulation thread-local storage)"),
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cl::Hidden, cl::value_desc("number"), cl::init(8));
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namespace {
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/// Lowers thread local variables on the XCore. Each thread local variable is
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/// expanded to an array of n elements indexed by the thread ID where n is the
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/// fixed number hardware threads supported by the device.
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struct XCoreLowerThreadLocal : public ModulePass {
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static char ID;
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XCoreLowerThreadLocal() : ModulePass(ID) {
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initializeXCoreLowerThreadLocalPass(*PassRegistry::getPassRegistry());
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}
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bool lowerGlobal(GlobalVariable *GV);
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bool runOnModule(Module &M);
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};
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}
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char XCoreLowerThreadLocal::ID = 0;
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INITIALIZE_PASS(XCoreLowerThreadLocal, "xcore-lower-thread-local",
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"Lower thread local variables", false, false)
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ModulePass *llvm::createXCoreLowerThreadLocalPass() {
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return new XCoreLowerThreadLocal();
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}
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static ArrayType *createLoweredType(Type *OriginalType) {
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return ArrayType::get(OriginalType, MaxThreads);
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}
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static Constant *
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createLoweredInitializer(ArrayType *NewType, Constant *OriginalInitializer) {
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SmallVector<Constant *, 8> Elements(MaxThreads);
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for (unsigned i = 0; i != MaxThreads; ++i) {
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Elements[i] = OriginalInitializer;
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}
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return ConstantArray::get(NewType, Elements);
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}
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static bool hasNonInstructionUse(GlobalVariable *GV) {
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for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;
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++UI)
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if (!isa<Instruction>(*UI))
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return true;
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return false;
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}
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static bool isZeroLengthArray(Type *Ty) {
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ArrayType *AT = dyn_cast<ArrayType>(Ty);
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return AT && (AT->getNumElements() == 0);
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}
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bool XCoreLowerThreadLocal::lowerGlobal(GlobalVariable *GV) {
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Module *M = GV->getParent();
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LLVMContext &Ctx = M->getContext();
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if (!GV->isThreadLocal())
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return false;
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// Skip globals that we can't lower and leave it for the backend to error.
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if (hasNonInstructionUse(GV) ||
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!GV->getType()->isSized() || isZeroLengthArray(GV->getType()))
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return false;
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// Create replacement global.
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ArrayType *NewType = createLoweredType(GV->getType()->getElementType());
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Constant *NewInitializer = createLoweredInitializer(NewType,
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GV->getInitializer());
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GlobalVariable *NewGV =
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new GlobalVariable(*M, NewType, GV->isConstant(), GV->getLinkage(),
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NewInitializer, "", 0, GlobalVariable::NotThreadLocal,
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GV->getType()->getAddressSpace(),
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GV->isExternallyInitialized());
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// Update uses.
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SmallVector<User *, 16> Users(GV->use_begin(), GV->use_end());
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for (unsigned I = 0, E = Users.size(); I != E; ++I) {
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User *U = Users[I];
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Instruction *Inst = cast<Instruction>(U);
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IRBuilder<> Builder(Inst);
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Function *GetID = Intrinsic::getDeclaration(GV->getParent(),
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Intrinsic::xcore_getid);
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Value *ThreadID = Builder.CreateCall(GetID);
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SmallVector<Value *, 2> Indices;
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Indices.push_back(Constant::getNullValue(Type::getInt64Ty(Ctx)));
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Indices.push_back(ThreadID);
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Value *Addr = Builder.CreateInBoundsGEP(NewGV, Indices);
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U->replaceUsesOfWith(GV, Addr);
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}
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// Remove old global.
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NewGV->takeName(GV);
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GV->eraseFromParent();
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return true;
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}
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bool XCoreLowerThreadLocal::runOnModule(Module &M) {
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// Find thread local globals.
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bool MadeChange = false;
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SmallVector<GlobalVariable *, 16> ThreadLocalGlobals;
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for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
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GVI != E; ++GVI) {
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GlobalVariable *GV = GVI;
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if (GV->isThreadLocal())
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ThreadLocalGlobals.push_back(GV);
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}
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for (unsigned I = 0, E = ThreadLocalGlobals.size(); I != E; ++I) {
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MadeChange |= lowerGlobal(ThreadLocalGlobals[I]);
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}
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return MadeChange;
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}
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