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