> Black nodes are value computations in general. Blue nodes are value computations that use the values of objects.
I don't quite understand the difference. Don't all value computations use the values of objects?
I don't quite understand the difference. Don't all value computations use the values of objects?
- The value computations of operators, like 5 + 6. These don't use the values of objects. They just use the values of their operands. The operands may be subexpressions that denote objects (like 5 + x), but it is the value computation of those subexpressions that uses the object's value, not the value computation of the operator.
- The value computations of expressions denoting objects where the expression is being used as an lvalue. These also don't use the values of objects - they only care about the object's storage location. I give an example in the article, which is the left operand of =.
- The value computation of expressions denoting objects where the expression is being used as an rvalue. This means lvalue-to-rvalue conversion is performed, which is conceptually "reading an object's value out of memory". This, therefore, uses the value of the object.
Objects correspond to locations in memory.
5 + 6 has operands which are rvalues (and thus not objects because you can't take their address).
if x is an int, then in the context of the expr 5+x, it is undergoing lvalue-to-rvalue conversion
Did I get that right?