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#include "slang-ir-lower-l-value-cast.h"
#include "slang-ir-clone.h"
#include "slang-ir-insts.h"
#include "slang-ir-util.h"
#include "slang-ir.h"
namespace Slang
{
struct LValueCastLoweringContext
{
void _addToWorkList(IRInst* inst)
{
if (!findOuterGeneric(inst) && !m_workList.contains(inst))
{
m_workList.add(inst);
}
}
void _processInst(IRInst* inst)
{
switch (inst->getOp())
{
case kIROp_InOutImplicitCast:
case kIROp_OutImplicitCast:
_processLValueCast(inst);
break;
default:
break;
}
}
void processModule()
{
_addToWorkList(m_module->getModuleInst());
while (m_workList.getCount() != 0)
{
IRInst* inst = m_workList.getLast();
m_workList.removeLast();
_processInst(inst);
for (auto child = inst->getLastChild(); child; child = child->getPrevInst())
{
_addToWorkList(child);
}
}
}
/// True if the conversion from a to b, can be achieved
/// via a reinterpret cast/bitcast
/// Only some targets can allow such conversions
bool _canReinterpretCast(IRType* a, IRType* b)
{
auto ptrA = as<IRPtrTypeBase>(a);
auto ptrB = as<IRPtrTypeBase>(b);
// They must both be pointers...
SLANG_ASSERT(ptrA && ptrB);
a = ptrA->getValueType();
b = ptrB->getValueType();
if (a->m_op == b->m_op)
{
if (auto matA = as<IRMatrixType>(a))
{
auto matB = static_cast<IRMatrixType*>(b);
if (getIntVal(matA->getColumnCount()) != getIntVal(matB->getColumnCount()))
{
return false;
}
a = matA->getElementType();
b = matB->getElementType();
}
else if (auto vecA = as<IRVectorType>(a))
{
auto vecB = static_cast<IRVectorType*>(b);
if (getIntVal(vecA->getElementCount()) != getIntVal(vecB->getElementCount()))
{
return false;
}
a = vecA->getElementType();
b = vecB->getElementType();
}
}
auto basicA = as<IRBasicType>(a);
auto basicB = as<IRBasicType>(b);
if (basicA && basicB)
{
auto baseA = basicA->getBaseType();
auto baseB = basicB->getBaseType();
const auto& infoA = BaseTypeInfo::getInfo(baseA);
const auto& infoB = BaseTypeInfo::getInfo(baseB);
// We allow reinterpret case for int type conversions of the same bit size for now
if (infoA.sizeInBytes == infoB.sizeInBytes &&
(infoA.flags & infoB.flags & BaseTypeInfo::Flag::Integer))
{
return true;
}
}
return false;
}
/// True if for HLSL the cast can be removed entirely
bool _canRemoveCastForHLSL(IRType* a, IRType* b)
{
// Currently _canReinterpret is exactly the same class of types that we can just ignore the
// cast totally for HLSL If _canReinterpretCast changes, this will need to be updated
return _canReinterpretCast(a, b);
}
void _processLValueCast(IRInst* castInst)
{
auto castOperand = castInst->getOperand(0);
auto fromType = castOperand->getDataType();
auto toType = castInst->getDataType();
switch (m_intermediateSourceLanguage)
{
case SourceLanguage::HLSL:
{
// If the conversion can just be ignored for HLSL, just remove it
if (_canRemoveCastForHLSL(fromType, toType))
{
castInst->replaceUsesWith(castOperand);
castInst->removeAndDeallocate();
return;
}
break;
}
case SourceLanguage::C:
case SourceLanguage::CPP:
case SourceLanguage::CUDA:
{
// For languages with pointers, out parameter differences can *sometimes* just be
// sidestepped with a reinterpret cast.
if (_canReinterpretCast(fromType, toType))
{
return;
}
break;
}
default:
break;
}
// If we can't use the other mechanisms we are going to do a conversion
// via a cast into a temporary of the approprite time before the useSite,
// then immediately after converting back into the original location.
//
// With a special case for uses which are just out - where we don't need to
// convert in.
// Okay we are going to replace the implicit casts with temporaries around call sites/uses.
List<IRUse*> useSites;
for (auto use = castInst->firstUse; use; use = use->nextUse)
{
useSites.add(use);
}
// If there is a name hint on the source, we'll copy it over to the temporaries
auto nameHintDecoration = castOperand->findDecoration<IRNameHintDecoration>();
IRBuilder builder(m_module);
auto toPtrType = as<IRPtrTypeBase>(toType);
auto fromPtrType = as<IRPtrTypeBase>(fromType);
if (!toPtrType || !fromPtrType)
{
// If either type is not a pointer type, we cannot process this L-value cast
return;
}
IRType* toValueType = toPtrType->getValueType();
IRType* fromValueType = fromPtrType->getValueType();
for (auto useSite : useSites)
{
auto user = useSite->getUser();
builder.setInsertBefore(user);
auto tmpVar = builder.emitVar(toValueType);
if (nameHintDecoration)
{
cloneDecoration(nameHintDecoration, tmpVar);
}
// If it's inout we convert via cast whats in the castOperand
if (castInst->getOp() == kIROp_InOutImplicitCast && user->getOp() != kIROp_Store)
{
builder.emitStore(
tmpVar,
builder.emitCast(toValueType, builder.emitLoad(castOperand)));
}
// Convert the temporary back to the original location
builder.setInsertAfter(user);
builder.emitStore(
castOperand,
builder.emitCast(fromValueType, builder.emitLoad(tmpVar)));
// Go through all of the operands of the use inst relacing, with the temporary
builder.replaceOperand(useSite, tmpVar);
}
// When we are done we can destroy the inst
castInst->removeAndDeallocate();
}
LValueCastLoweringContext(TargetProgram* target, IRModule* module)
: m_targetProgram(target), m_module(module)
{
m_intermediateSourceLanguage = getIntermediateSourceLanguageForTarget(target);
}
// The intermediate source language used to produce code for the target.
// If no intermediate source language is used will be SourceLanguage::Unknown.
SourceLanguage m_intermediateSourceLanguage = SourceLanguage::Unknown;
TargetProgram* m_targetProgram;
IRModule* m_module;
OrderedHashSet<IRInst*> m_workList;
};
void lowerLValueCast(TargetProgram* target, IRModule* module)
{
LValueCastLoweringContext context(target, module);
context.processModule();
}
} // namespace Slang
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