Wait so when you call a function, you don't have to emit the code to
push all the register variables on to the stack and then feed them back in
when you return? The VM does this for you?
On Dec 1, P T Withington wrote:
> The semantics of Javascript require that all variables declared in a function
> have the scope of the entire function. The compiler implements this by
> allocating a register for every variable declaration in a function on function
> entry. So, you can put your `var`s wherever you like, the compiler has to
> emit the same code.
>
> [I don't know how the Flash VM implements its registers, but my educated guess
> is that VM registers are just slots in a stack so there is no overhead to
> saving/restoring registers other than adjusting the stack pointer.]
>
> On 1 Dec 2005, at 20:59, Adam Wolff wrote:
>
> > If I have this:
> >
> > function func1(){
> > var a, b;
> > a=1;
> > func2();
> > b=2;
> > return a+b;
> > }
> >
> > Question for the compiler folks: I assume that a and b are register
> > variables. Is the compiler smart enough to know that I haven't assigned a
> > value to b before the call to func2, so that its value does not need to be
> > preserved on the stack when the call is made? If not, if I moved the var b
> > declaration below the function call, would that help?
> >
> > A
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>
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