void ClastStmtCodeGen::codegenForGPGPU(const clast_for *F) {
BasicBlock::iterator LoopBody;
SetVector<Value *> Values;
SetVector<Value *> IVS;
std::vector<int> NumIterations;
PTXGenerator::ValueToValueMapTy VMap;
assert(!GPUTriple.empty() &&
"Target triple should be set properly for GPGPU code generation.");
PTXGenerator PTXGen(Builder, P, GPUTriple);
// Get original IVS and ScopStmt
unsigned TiledLoopDepth, NonPLoopDepth;
const clast_stmt *InnerStmt =
getScheduleInfo(F, NumIterations, TiledLoopDepth, NonPLoopDepth);
const clast_stmt *TmpStmt;
const clast_user_stmt *U;
const clast_for *InnerFor;
if (CLAST_STMT_IS_A(InnerStmt, stmt_for)) {
InnerFor = (const clast_for *)InnerStmt;
TmpStmt = InnerFor->body;
} else
TmpStmt = InnerStmt;
U = (const clast_user_stmt *)TmpStmt;
ScopStmt *Statement = (ScopStmt *)U->statement->usr;
for (unsigned i = 0; i < Statement->getNumIterators() - NonPLoopDepth; i++) {
const Value *IV = Statement->getInductionVariableForDimension(i);
IVS.insert(const_cast<Value *>(IV));
}
unsigned OutBytes;
Values = getGPUValues(OutBytes);
PTXGen.setOutputBytes(OutBytes);
PTXGen.startGeneration(Values, IVS, VMap, &LoopBody);
BasicBlock::iterator AfterLoop = Builder.GetInsertPoint();
Builder.SetInsertPoint(LoopBody);
BasicBlock *AfterBB = 0;
if (NonPLoopDepth) {
Value *LowerBound, *UpperBound, *IV, *Stride;
Type *IntPtrTy = getIntPtrTy();
LowerBound = ExpGen.codegen(InnerFor->LB, IntPtrTy);
UpperBound = ExpGen.codegen(InnerFor->UB, IntPtrTy);
Stride = Builder.getInt(APInt_from_MPZ(InnerFor->stride));
IV = createLoop(LowerBound, UpperBound, Stride, Builder, P, AfterBB,
CmpInst::ICMP_SLE);
const Value *OldIV_ = Statement->getInductionVariableForDimension(2);
Value *OldIV = const_cast<Value *>(OldIV_);
VMap.insert(std::make_pair<Value *, Value *>(OldIV, IV));
}
updateWithValueMap(VMap);
BlockGenerator::generate(Builder, *Statement, ValueMap, P);
if (AfterBB)
Builder.SetInsertPoint(AfterBB->begin());
// FIXME: The replacement of the host base address with the parameter of ptx
// subfunction should have been done by updateWithValueMap. We use the
// following codes to avoid affecting other parts of Polly. This should be
// fixed later.
Function *FN = Builder.GetInsertBlock()->getParent();
for (unsigned j = 0; j < Values.size(); j++) {
Value *baseAddr = Values[j];
for (Function::iterator B = FN->begin(); B != FN->end(); ++B) {
for (BasicBlock::iterator I = B->begin(); I != B->end(); ++I)
I->replaceUsesOfWith(baseAddr, ValueMap[baseAddr]);
}
}
Builder.SetInsertPoint(AfterLoop);
PTXGen.setLaunchingParameters(NumIterations[0], NumIterations[1],
NumIterations[2], NumIterations[3]);
PTXGen.finishGeneration(FN);
}
void PTXGenerator::createSubfunction(SetVector<Value *> &UsedValues,
SetVector<Value *> &OriginalIVS,
PTXGenerator::ValueToValueMapTy &VMap,
Function **SubFunction) {
Function *FN = createSubfunctionDefinition(UsedValues.size());
Module *M = getModule();
LLVMContext &Context = FN->getContext();
IntegerType *Ty = Builder.getInt64Ty();
// Store the previous basic block.
BasicBlock *PrevBB = Builder.GetInsertBlock();
// Create basic blocks.
BasicBlock *HeaderBB = BasicBlock::Create(Context, "ptx.setup", FN);
BasicBlock *ExitBB = BasicBlock::Create(Context, "ptx.exit", FN);
BasicBlock *BodyBB = BasicBlock::Create(Context, "ptx.loop_body", FN);
DominatorTree &DT = P->getAnalysis<DominatorTree>();
DT.addNewBlock(HeaderBB, PrevBB);
DT.addNewBlock(ExitBB, HeaderBB);
DT.addNewBlock(BodyBB, HeaderBB);
Builder.SetInsertPoint(HeaderBB);
// Insert VMap items with maps of array base address on the host to base
// address on the device.
Function::arg_iterator AI = FN->arg_begin();
for (unsigned j = 0; j < UsedValues.size(); j++) {
Value *BaseAddr = UsedValues[j];
Type *ArrayTy = BaseAddr->getType();
Value *Param = Builder.CreateBitCast(AI, ArrayTy);
VMap.insert(std::make_pair<Value *, Value *>(BaseAddr, Param));
AI++;
}
// FIXME: These intrinsics should be inserted on-demand. However, we insert
// them all currently for simplicity.
Function *GetNctaidX =
Intrinsic::getDeclaration(M, Intrinsic::ptx_read_nctaid_x);
Function *GetNctaidY =
Intrinsic::getDeclaration(M, Intrinsic::ptx_read_nctaid_y);
Function *GetCtaidX =
Intrinsic::getDeclaration(M, Intrinsic::ptx_read_ctaid_x);
Function *GetCtaidY =
Intrinsic::getDeclaration(M, Intrinsic::ptx_read_ctaid_y);
Function *GetNtidX = Intrinsic::getDeclaration(M, Intrinsic::ptx_read_ntid_x);
Function *GetNtidY = Intrinsic::getDeclaration(M, Intrinsic::ptx_read_ntid_y);
Function *GetTidX = Intrinsic::getDeclaration(M, Intrinsic::ptx_read_tid_x);
Function *GetTidY = Intrinsic::getDeclaration(M, Intrinsic::ptx_read_tid_y);
Value *GridWidth = Builder.CreateCall(GetNctaidX);
GridWidth = Builder.CreateIntCast(GridWidth, Ty, false);
Value *GridHeight = Builder.CreateCall(GetNctaidY);
GridHeight = Builder.CreateIntCast(GridHeight, Ty, false);
Value *BlockWidth = Builder.CreateCall(GetNtidX);
BlockWidth = Builder.CreateIntCast(BlockWidth, Ty, false);
Value *BlockHeight = Builder.CreateCall(GetNtidY);
BlockHeight = Builder.CreateIntCast(BlockHeight, Ty, false);
Value *BIDx = Builder.CreateCall(GetCtaidX);
BIDx = Builder.CreateIntCast(BIDx, Ty, false);
Value *BIDy = Builder.CreateCall(GetCtaidY);
BIDy = Builder.CreateIntCast(BIDy, Ty, false);
Value *TIDx = Builder.CreateCall(GetTidX);
TIDx = Builder.CreateIntCast(TIDx, Ty, false);
Value *TIDy = Builder.CreateCall(GetTidY);
TIDy = Builder.CreateIntCast(TIDy, Ty, false);
Builder.CreateBr(BodyBB);
Builder.SetInsertPoint(BodyBB);
unsigned NumDims = OriginalIVS.size();
std::vector<Value *> Substitutions;
Value *BlockID, *ThreadID;
switch (NumDims) {
case 1: {
Value *BlockSize =
Builder.CreateMul(BlockWidth, BlockHeight, "p_gpu_blocksize");
BlockID = Builder.CreateMul(BIDy, GridWidth, "p_gpu_index_i");
BlockID = Builder.CreateAdd(BlockID, BIDx);
BlockID = Builder.CreateMul(BlockID, BlockSize);
ThreadID = Builder.CreateMul(TIDy, BlockWidth, "p_gpu_index_j");
ThreadID = Builder.CreateAdd(ThreadID, TIDx);
ThreadID = Builder.CreateAdd(ThreadID, BlockID);
Substitutions.push_back(ThreadID);
break;
}
case 2: {
BlockID = Builder.CreateMul(BIDy, GridWidth, "p_gpu_index_i");
BlockID = Builder.CreateAdd(BlockID, BIDx);
Substitutions.push_back(BlockID);
ThreadID = Builder.CreateMul(TIDy, BlockWidth, "p_gpu_index_j");
ThreadID = Builder.CreateAdd(ThreadID, TIDx);
Substitutions.push_back(ThreadID);
break;
}
case 3: {
BlockID = Builder.CreateMul(BIDy, GridWidth, "p_gpu_index_i");
BlockID = Builder.CreateAdd(BlockID, BIDx);
Substitutions.push_back(BlockID);
Substitutions.push_back(TIDy);
Substitutions.push_back(TIDx);
break;
}
case 4: {
Substitutions.push_back(BIDy);
Substitutions.push_back(BIDx);
Substitutions.push_back(TIDy);
Substitutions.push_back(TIDx);
break;
}
default:
assert(true &&
"We cannot transform parallel loops whose depth is larger than 4.");
return;
}
assert(OriginalIVS.size() == Substitutions.size() &&
"The size of IVS should be equal to the size of substitutions.");
for (unsigned i = 0; i < OriginalIVS.size(); ++i) {
VMap.insert(
std::make_pair<Value *, Value *>(OriginalIVS[i], Substitutions[i]));
}
Builder.CreateBr(ExitBB);
Builder.SetInsertPoint(--Builder.GetInsertPoint());
BasicBlock::iterator LoopBody = Builder.GetInsertPoint();
// Add the termination of the ptx-device subfunction.
Builder.SetInsertPoint(ExitBB);
Builder.CreateRetVoid();
Builder.SetInsertPoint(LoopBody);
*SubFunction = FN;
}