Re: Number of compiler passes

On Wed, 30 Jul 2008 17:56:11 -0700, Barry Kelly
<barry.kelly@codegear.com> wrote:


>George Neuner wrote:
>
> > Ok, we have different definitions of expression. I consider an
> > expression to compute something or cause a side effect like altering
> > control flow. To me, a variable reference like "A[X]" is a
> > subexpression that can't stand on its own.
>
>I think a symbolic location reference like A[X] is an appropriate
>structure to have in an expression tree, and that it has a type, and
>that when evaluated for computation it acts as an rvalue, but it can
>also serve as an lvalue if it occurs e.g. as the operand to an
>address-of unary expression node, or on the lhs of an assignment.


I agree that the location reference is a sub-part of an expression
tree, but I don't agree that it is an expression itself.


Anyway that is not really important. What is important is the
understanding that the notions of L-value and R-value belong to a
different abstraction level than the notions of "read-only",
"write-only" and "read/write". The OP was conflating the concepts and
I was attempting to correct his misinterpretation.


George

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