private Expression GetStackValue(int offset, DataType accessDataType)
{
Expression value;
if (StackState.TryGetValue(offset, out value))
{
if (value == Constant.Invalid)
{
return(value);
}
int excess = accessDataType.Size - value.DataType.Size;
if (excess == 0)
{
return(value);
}
if (excess > 0)
{
// Example: word32 fetch from SP+04, where SP+04 is a word16 and SP+06 is a word16
int remainder = offset + value.DataType.Size;
Expression v2;
if (StackState.TryGetValue(remainder, out v2))
{
if (v2 == Constant.Invalid || value == Constant.Invalid)
{
return(Constant.Invalid);
}
if (v2.DataType.Size + value.DataType.Size != accessDataType.Size)
{
return(Constant.Invalid);
}
//$BUGBUG: should evaluate the MkSequence, possibly creating a longer constant if v2 and value are
// constant.
//$BUGBUG: the sequence below is little-endian!!!
return(new MkSequence(accessDataType, v2, value));
}
}
else
{
// Example: fetching a byte from SP+04, which previously was assigned an int32.
return(new Cast(accessDataType, value));
}
}
else
{
int offset2;
if (StackState.TryGetLowerBoundKey(offset, out offset2))
{
var value2 = StackState[offset2];
if (offset2 + value2.DataType.Size > offset)
{
return(new Slice(accessDataType, StackState[offset2], ((offset - offset2) * 8)));
}
}
}
return(Constant.Invalid);
}