internal static void BuildNotifierReaderPromisePollFunction(FunctionModuleContext moduleContext, NIType signature, LLVMValueRef notifierReaderPromisePollFunction)
{
NIType notifierReaderPromiseType = signature.GetGenericParameters().ElementAt(0),
valueType = notifierReaderPromiseType.GetGenericParameters().ElementAt(0);
LLVMTypeRef optionValueLLVMType = moduleContext.LLVMContext.AsLLVMType(valueType.CreateOption()),
optionOptionValueLLVMType = moduleContext.LLVMContext.AsLLVMType(valueType.CreateOption().CreateOption());
LLVMBasicBlockRef entryBlock = notifierReaderPromisePollFunction.AppendBasicBlock("entry"),
writerReadyBlock = notifierReaderPromisePollFunction.AppendBasicBlock("writerReady"),
writerDroppedWithoutValueBlock = notifierReaderPromisePollFunction.AppendBasicBlock("writerDroppedWithoutValue"),
writerDroppedWithValueBlock = notifierReaderPromisePollFunction.AppendBasicBlock("writerDroppedWithValue"),
endBlock = notifierReaderPromisePollFunction.AppendBasicBlock("end");
var builder = moduleContext.LLVMContext.CreateIRBuilder();
builder.PositionBuilderAtEnd(entryBlock);
LLVMValueRef notifierReaderPromisePtr = notifierReaderPromisePollFunction.GetParam(0u),
waker = notifierReaderPromisePollFunction.GetParam(1u),
pollResultPtr = notifierReaderPromisePollFunction.GetParam(2u),
notifierReaderPromise = builder.CreateLoad(notifierReaderPromisePtr, "notifierReaderPromise"),
refCountPtr = builder.CreateExtractValue(notifierReaderPromise, 0u, "refCountPtr"),
sharedDataPtr = builder.CreateStructGEP(refCountPtr, 1u, "sharedDataPtr"),
wakerPtr = builder.CreateStructGEP(sharedDataPtr, SharedDataWakerFieldIndex, "wakerPtr"),
statePtr = builder.CreateStructGEP(sharedDataPtr, SharedDataStateFieldIndex, "statePtr");
builder.CreateStore(waker, wakerPtr);
// This is Release because it needs the writer thread to observe the waker store,
// and Acquire because it may need to observe the writer thread's value store.
LLVMValueRef oldState = builder.CreateAtomicRMW(
LLVMAtomicRMWBinOp.LLVMAtomicRMWBinOpOr,
statePtr,
moduleContext.LLVMContext.AsLLVMValue(ReaderWaitingForValue),
LLVMAtomicOrdering.LLVMAtomicOrderingAcquireRelease,
false),
oldWriterState = builder.CreateAnd(oldState, moduleContext.LLVMContext.AsLLVMValue(WriterStateMask), "oldWriterState");
LLVMValueRef writerStateSwitch = builder.CreateSwitch(oldWriterState, writerReadyBlock, 2u);
writerStateSwitch.AddCase(moduleContext.LLVMContext.AsLLVMValue(WriterDroppedWithoutValue), writerDroppedWithoutValueBlock);
writerStateSwitch.AddCase(moduleContext.LLVMContext.AsLLVMValue(WriterDroppedWithValue), writerDroppedWithValueBlock);
builder.PositionBuilderAtEnd(writerReadyBlock);
// output None
builder.CreateStore(LLVMTypeRef.ConstNull(optionOptionValueLLVMType), pollResultPtr);
builder.CreateRetVoid();
builder.PositionBuilderAtEnd(writerDroppedWithoutValueBlock);
// output Some(None)
builder.CreateStore(moduleContext.LLVMContext.BuildOptionValue(builder, optionOptionValueLLVMType, LLVMTypeRef.ConstNull(optionValueLLVMType)), pollResultPtr);
builder.CreateBr(endBlock);
builder.PositionBuilderAtEnd(writerDroppedWithValueBlock);
// output Some(Some(value))
LLVMValueRef valuePtr = builder.CreateStructGEP(sharedDataPtr, SharedDataValueFieldIndex, "valuePtr"),
value = builder.CreateLoad(valuePtr, "value");
builder.CreateStore(moduleContext.LLVMContext.BuildOptionValue(builder, optionOptionValueLLVMType, moduleContext.LLVMContext.BuildOptionValue(builder, optionValueLLVMType, value)), pollResultPtr);
builder.CreateBr(endBlock);
builder.PositionBuilderAtEnd(endBlock);
LLVMValueRef decrementRefCountFunction = GetDecrementRefCountFunction(moduleContext, valueType.CreateNotifierSharedDataType());
builder.CreateCall(decrementRefCountFunction, new LLVMValueRef[] { refCountPtr }, string.Empty);
builder.CreateRetVoid();
}
