bool Encode(uchar symbol, Output& result)
{
if(symbol == ' ')
{
LoadFromAddress(AddressOf(Space), result);
return true;
}
if(!ConvertSymbol(symbol, symbol))
{
return false;
}
LoadFromAddress(AddressOf(MorseTable[symbol - '0']), result);
return true;
}
Operand* ConstantFolder::HandleLoad(Operand* sourceOp) {
// Handle cases when we know the result is undefined.
// load undef -> undef
// load nullptr -> undef
if(sourceOp->IsUndefinedConstant()) {
return sourceOp;
}
else if(sourceOp->IsNullConstant()) {
return GetUndefined(sourceOp);
}
// Handle first the simple cases when we load directly from a global variable.
auto loadType = sourceOp->GetType()->As<PointerType>()->PointeeType();
if(auto variableRef = sourceOp->IsVariableReference()) {
return LoadFromGlobal(sourceOp, loadType, 0 /* start offset */);
}
// Try to load from an 'addr', 'index' or 'elem' instruction that index into
// a global variable (for example, 'a[i]', 'a.b', 'a.c[i].d', '*(p + 2)', etc.).
return LoadFromAddress(sourceOp, loadType, 0 /* start offset */);
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Operand* ConstantFolder::LoadFromAddress(Operand* op, const Type* loadType,
__int64 offset) {
// If the operand has a defining instruction then we try to compute
// the offset from which we should load. If it's a variable reference
// we try to load from the offset that was already computed.
if(op->HasDefiningInstruction() == false) {
return LoadFromGlobal(op, loadType, offset);
}
auto instr = op->DefiningInstruction();
switch(instr->GetOpcode()) {
case Instr_Index: {
// If the index operand is not a constant give up.
auto indexInstr = instr->As<IndexInstr>();
auto indexConst = indexInstr->IndexOp()->As<IntConstant>();
if(indexConst == nullptr) {
return nullptr;
}
// The type of the base is 'pointer-to-array', so we need to strip the pointer.
auto elementType = indexInstr->GetElementType();
__int64 index = indexConst->Value();
__int64 elemSize = TypeInfo::GetSize(elementType, target_);
// The offset is incremented by the index multiplied with the element size.
__int64 newOffset = offset + (index * elemSize);
return LoadFromAddress(indexInstr->BaseOp(), loadType, newOffset);
}
case Instr_Element: {
auto elemInstr = instr->As<ElementInstr>();
__int64 index = elemInstr->GetFieldIndex();
// The type of the base is 'pointer-to-record',
// so we need to strip the pointer.
auto recordType = elemInstr->GetRecordType();
// Obtain the offset of the selected field.
// The new offset is the old one added with the field offset.
__int64 fieldOffset = recordType->Fields()[index].FieldOffset;
__int64 newOffset = offset + fieldOffset;
return LoadFromAddress(elemInstr->BaseOp(), loadType, newOffset);
}
case Instr_Address: {
// If the index operand is not a constant give up.
auto addrInstr = instr->As<AddressInstr>();
auto indexConst = addrInstr->IndexOp()->As<IntConstant>();
if(indexConst == nullptr) {
return nullptr;
}
// The type of the base is 'pointer-to-object',
// so we need to strip the pointer.
auto objectType = addrInstr->GetPointeeType();
__int64 index = indexConst->Value();
__int64 elemSize = TypeInfo::GetSize(objectType, target_);
// The offset is incremented by the index multiplied with the object size.
__int64 newOffset = offset + (index * elemSize);
return LoadFromAddress(addrInstr->BaseOp(), loadType, newOffset);
}
case Instr_Ptop: {
// This instruction is ignored (the previous recursion step
// has already taken care about its effects).
auto ptopInstr = instr->As<PtopInstr>();
auto targetInstr = ptopInstr->TargetOp()->DefiningInstruction();
return LoadFromAddress(ptopInstr->TargetOp(), loadType, offset);
}
case Instr_Load: {
// This happens when the variable is a pointer.
auto loadInstr = instr->As<LoadInstr>();
return LoadFromAddress(loadInstr->SourceOp(), loadType, offset);
}
default: {
// All other cases don't lead to a constant operand.
return nullptr;
}
}
}
