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#include "slang-ir-legalize-vector-types.h"
#include "slang-ir-insts.h"
#include "slang-ir-util.h"
#include "slang-ir.h"
namespace Slang
{
struct VectorTypeLoweringContext
{
IRModule* module;
DiagnosticSink* sink;
InstWorkList workList;
InstHashSet workListSet;
Dictionary<IRInst*, IRInst*> replacements;
VectorTypeLoweringContext(IRModule* module)
: module(module), workList(module), workListSet(module)
{
}
void addToWorkList(IRInst* inst)
{
for (auto ii = inst->getParent(); ii; ii = ii->getParent())
{
if (as<IRGeneric>(ii))
return;
}
if (workListSet.contains(inst))
return;
workList.add(inst);
workListSet.add(inst);
}
bool is1Vector(IRType* t)
{
const auto lenLit = composeGetters<IRIntLit>(t, &IRVectorType::getElementCount);
return lenLit ? getIntVal(lenLit) == 1 : false;
};
bool has1VectorType(IRInst* i) { return is1Vector(i->getDataType()); }
bool has1VectorPtrType(IRInst* i)
{
const auto ptr = as<IRPtrTypeBase>(i->getDataType());
return ptr && is1Vector(ptr->getValueType());
}
// If necessary, this returns a new instruction which operates on the
// single component of a 1-vector.
// If no new instruction was created, then the old one is returned
// unmodified, when we replace the 1-vector type globally, only then
// will the return type of that instruction be updated; thus you
// shouldn't rely on this function returning an instruction with a non
// 1-vector return type (even if we didn't have the deferred
// replacement this is not true, as it'll only eliminate at most one
// level of 1-vectornes, and nested vectors exist)
IRInst* getReplacement(IRInst* inst)
{
IRInst* replacement = nullptr;
if (replacements.tryGetValue(inst, replacement))
return replacement;
IRBuilder builder(module);
builder.setInsertBefore(inst);
replacement = instMatch<IRInst*>(
inst,
nullptr,
// The following match instructions which take a 1-vector as an
// operand and are sensitive to the fact that it's a vector.
// Likewise for pointers.
[&](IRGetElement* getElement)
{
const auto base = getElement->getBase();
return has1VectorType(base) ? getReplacement(base) : nullptr;
},
[&](IRSwizzle* swizzle) -> IRInst*
{
const auto swizzled = swizzle->getBase();
// Is this a swizzle of a 1-vector
if (has1VectorType(swizzled))
{
// If this is a unary swizzle, just return the element
// inside
const auto scalar = getReplacement(swizzled);
if (swizzle->getElementCount() == 1)
return scalar;
// Otherwise, create a broadcast of this scalar
else
return builder.emitMakeVectorFromScalar(swizzle->getFullType(), scalar);
}
return nullptr;
},
[&](IRGetElementPtr* gep)
{
const auto base = gep->getBase();
return has1VectorPtrType(base) ? getReplacement(base) : nullptr;
},
[&](IRSwizzledStore* swizzledStore)
{
const auto base = swizzledStore->getDest();
return has1VectorPtrType(base)
? builder.emitStore(getReplacement(base), swizzledStore->getSource())
: nullptr;
},
// The following should match any instruction which can construct,
// specifically, a 1-vector. For example 'MakeVector'
//
// Instruction like, for example, arithmetic instructions don't
// need to be handled here, and they'll be fixed by the global
// 1-vector to scalar type replacement.
[&](IRMakeVectorFromScalar* makeVec)
{ return has1VectorType(makeVec) ? getReplacement(makeVec->getOperand(0)) : nullptr; },
[&](IRMakeVector* makeVec)
{ return has1VectorType(makeVec) ? getReplacement(makeVec->getOperand(0)) : nullptr; },
// Otherwise if this is a 1-vector type itself, replace it with
// the scalar version.
[&](IRVectorType* vecTy)
{ return is1Vector(vecTy) ? getReplacement(vecTy->getElementType()) : nullptr; });
// Sadly it's not really possible to catch missing cases here, as
// there are heaps of instructions which don't do anything special
// with vectors, but can take or return vector types, for example
// arithmetic, IRGetElement, IRGetField etc...
// If we did get a replacement, add that to our mapping and return
// it, otherwise return the original (to maybe be updated later)
if (replacement)
{
replacements.set(inst, replacement);
addToWorkList(replacement);
}
return replacement ? replacement : inst;
}
void processModule()
{
addToWorkList(module->getModuleInst());
while (workList.getCount() != 0)
{
IRInst* inst = workList.getLast();
workList.removeLast();
workListSet.remove(inst);
// Run this inst through the replacer
getReplacement(inst);
for (auto child = inst->getLastChild(); child; child = child->getPrevInst())
{
addToWorkList(child);
}
}
// Apply all replacements
//
// It's important to defer this as if we were updating things
// on-the-fly we would be losing information about what was
// actually a 1-vector or not. The alternative would be cloning
// every function with a 1-vector type as we process it, and
// cleaning up at the end. This involves less copying, but is
// necessarily a little less type-safe.
for (const auto& [old, replacement] : replacements)
{
if (old != replacement)
{
old->replaceUsesWith(replacement);
old->removeAndDeallocate();
}
}
}
};
void legalizeVectorTypes(IRModule* module, DiagnosticSink* sink)
{
VectorTypeLoweringContext context(module);
context.sink = sink;
context.processModule();
}
} // namespace Slang
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