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// slang-ir-lower-generic-existential.cpp
#include "slang-ir-lower-existential.h"
#include "slang-ir-generics-lowering-context.h"
#include "slang-ir.h"
#include "slang-ir-insts.h"
namespace Slang
{
bool isCPUTarget(TargetRequest* targetReq);
bool isCUDATarget(TargetRequest* targetReq);
struct ExistentialLoweringContext
{
SharedGenericsLoweringContext* sharedContext;
void processMakeExistential(IRMakeExistentialWithRTTI* inst)
{
IRBuilder builderStorage(sharedContext->sharedBuilderStorage);
auto builder = &builderStorage;
builder->setInsertBefore(inst);
auto value = inst->getWrappedValue();
auto valueType = sharedContext->lowerType(builder, value->getDataType());
auto witnessTableType = cast<IRWitnessTableTypeBase>(inst->getWitnessTable()->getDataType());
auto interfaceType = witnessTableType->getConformanceType();
auto witnessTableIdType = builder->getWitnessTableIDType((IRType*)interfaceType);
auto anyValueSize = sharedContext->getInterfaceAnyValueSize(interfaceType, inst->sourceLoc);
auto anyValueType = builder->getAnyValueType(anyValueSize);
auto rttiType = builder->getRTTIHandleType();
auto tupleType = builder->getTupleType(rttiType, witnessTableIdType, anyValueType);
IRInst* rttiObject = inst->getRTTI();
if (auto type = as<IRType>(rttiObject))
{
rttiObject = sharedContext->maybeEmitRTTIObject(type);
rttiObject = builder->emitGetAddress(rttiType, rttiObject);
}
IRInst* packedValue = value;
if (valueType->getOp() != kIROp_AnyValueType)
packedValue = builder->emitPackAnyValue(anyValueType, value);
IRInst* tupleArgs[] = {rttiObject, inst->getWitnessTable(), packedValue};
auto tuple = builder->emitMakeTuple(tupleType, 3, tupleArgs);
inst->replaceUsesWith(tuple);
inst->removeAndDeallocate();
}
// Translates `createExistentialObject` insts, which takes a user defined
// type id and user defined value and turns into an existential value,
// into a `makeTuple` inst that makes the tuple representing the lowered
// existential value.
void processCreateExistentialObject(IRCreateExistentialObject* inst)
{
IRBuilder builderStorage(sharedContext->sharedBuilderStorage);
auto builder = &builderStorage;
builder->setInsertBefore(inst);
// The result type of this `createExistentialObject` inst should already
// be lowered into a `TupleType(rttiType, WitnessTableIDType, AnyValueType)`
// in the previous `lowerGenericType` pass.
auto tupleType = inst->getDataType();
auto witnessTableIdType = cast<IRWitnessTableIDType>(tupleType->getOperand(1));
auto anyValueType = cast<IRAnyValueType>(tupleType->getOperand(2));
// Create a null value for `rttiObject` for now since it will not be used.
auto uint2Type = builder->getVectorType(
builder->getUIntType(), builder->getIntValue(builder->getIntType(), 2));
IRInst* zero = builder->getIntValue(builder->getUIntType(), 0);
IRInst* zeroVectorArgs[] = { zero, zero };
IRInst* rttiObject = builder->emitMakeVector(uint2Type, 2, zeroVectorArgs);
// Pack the user provided value into `AnyValue`.
IRInst* packedValue = inst->getValue();
if (packedValue->getDataType()->getOp() != kIROp_AnyValueType)
packedValue = builder->emitPackAnyValue(anyValueType, packedValue);
// Use the user provided `typeID` value as the witness table ID field in the
// newly constructed tuple.
// All `WitnessTableID` types are lowered into `uint2`s, so we need to create
// a `uint2` value from `typeID` to stay consistent with the convention.
IRInst* vectorArgs[2] = {
inst->getTypeID(), builder->getIntValue(builder->getUIntType(), 0)};
IRInst* typeIdValue = builder->emitMakeVector(uint2Type, 2, vectorArgs);
typeIdValue = builder->emitBitCast(witnessTableIdType, typeIdValue);
IRInst* tupleArgs[] = {rttiObject, typeIdValue, packedValue};
auto tuple = builder->emitMakeTuple(tupleType, 3, tupleArgs);
inst->replaceUsesWith(tuple);
inst->removeAndDeallocate();
}
IRInst* extractTupleElement(IRBuilder* builder, IRInst* value, UInt index)
{
auto tupleType = cast<IRTupleType>(sharedContext->lowerType(builder, value->getDataType()));
auto getElement = builder->emitGetTupleElement(
(IRType*)tupleType->getOperand(index),
value,
index);
return getElement;
}
void processExtractExistentialElement(IRInst* extractInst, UInt elementId)
{
IRBuilder builderStorage(sharedContext->sharedBuilderStorage);
auto builder = &builderStorage;
builder->setInsertBefore(extractInst);
auto element = extractTupleElement(builder, extractInst->getOperand(0), elementId);
extractInst->replaceUsesWith(element);
extractInst->removeAndDeallocate();
}
void processExtractExistentialValue(IRExtractExistentialValue* inst)
{
processExtractExistentialElement(inst, 2);
}
void processExtractExistentialWitnessTable(IRExtractExistentialWitnessTable* inst)
{
processExtractExistentialElement(inst, 1);
}
void processExtractExistentialType(IRExtractExistentialType* inst)
{
processExtractExistentialElement(inst, 0);
}
void processGetValueFromBoundInterface(IRGetValueFromBoundInterface* inst)
{
IRBuilder builderStorage(sharedContext->sharedBuilderStorage);
auto builder = &builderStorage;
builder->setInsertBefore(inst);
// A value of interface will lower as a tuple, and
// the third element of that tuple represents the
// concrete value that was put into the existential.
//
auto element = extractTupleElement(builder, inst->getOperand(0), 2);
auto elementType = element->getDataType();
// There are two cases we expect to see for that
// tuple element.
//
IRInst* replacement = nullptr;
if(as<IRPseudoPtrType>(elementType))
{
// The first case is when legacy static specialization
// is applied, and the element is a "pseudo-pointer."
//
// Semantically, we should emit a (pseudo-)load from the pseudo-pointer
// to go from `PseudoPtr<T>` to `T`.
//
// TODO: Actually introduce and emit a "psedudo-load" instruction
// here. For right now we are just using the value directly and
// downstream passes seem okay with it, but it isn't really
// type-correct to be doing this.
//
replacement = element;
}
else
{
// The second case is when the dynamic-dispatch layout is
// being used, and the element is an "any-value."
//
// In this case we need to emit an unpacking operation
// to get from `AnyValue` to `T`.
//
SLANG_ASSERT(as<IRAnyValueType>(elementType));
replacement = builder->emitUnpackAnyValue(inst->getFullType(), element);
}
inst->replaceUsesWith(replacement);
inst->removeAndDeallocate();
}
void processInst(IRInst* inst)
{
if (auto makeExistential = as<IRMakeExistentialWithRTTI>(inst))
{
processMakeExistential(makeExistential);
}
else if (auto createExistentialObject = as<IRCreateExistentialObject>(inst))
{
processCreateExistentialObject(createExistentialObject);
}
else if (auto getValueFromBoundInterface = as<IRGetValueFromBoundInterface>(inst))
{
processGetValueFromBoundInterface(getValueFromBoundInterface);
}
else if (auto extractExistentialVal = as<IRExtractExistentialValue>(inst))
{
processExtractExistentialValue(extractExistentialVal);
}
else if (auto extractExistentialType = as<IRExtractExistentialType>(inst))
{
processExtractExistentialType(extractExistentialType);
}
else if (auto extractExistentialWitnessTable = as<IRExtractExistentialWitnessTable>(inst))
{
processExtractExistentialWitnessTable(extractExistentialWitnessTable);
}
}
void processModule()
{
// We start by initializing our shared IR building state,
// since we will re-use that state for any code we
// generate along the way.
//
SharedIRBuilder* sharedBuilder = &sharedContext->sharedBuilderStorage;
sharedBuilder->init(sharedContext->module);
sharedContext->addToWorkList(sharedContext->module->getModuleInst());
while (sharedContext->workList.getCount() != 0)
{
IRInst* inst = sharedContext->workList.getLast();
sharedContext->workList.removeLast();
sharedContext->workListSet.Remove(inst);
processInst(inst);
for (auto child = inst->getLastChild(); child; child = child->getPrevInst())
{
sharedContext->addToWorkList(child);
}
}
}
};
void lowerExistentials(SharedGenericsLoweringContext* sharedContext)
{
ExistentialLoweringContext context;
context.sharedContext = sharedContext;
context.processModule();
}
}
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