Re: lazy execution optimization

[Sylvain Pion <Sylvain dot Pion at sophia dot inria dot fr>]

On Sun, Sep 26, 1999 at 06:14:49PM -0400, Steven W. Orr wrote:
> I'm definitely not a qualified person to answer this, but have you tried
> the following construct to see if the outcome is affected:
> 
> int f (double a, double b)
> {
>   double c;
>   c = a+b;
>   if (a > 0.0)
>     return 0;
>   else if (c > 0.0)
>     return 1;
>   else
>     return 2;
> }

It doesn't change anything.
Let me be more clear.  More generally, if I have a block:

  {
    computing some data (A) needed for "test" or for both branches.
    computing some data (B) not needed for the test, nor the exit branch.

    if (test) { exit the block; }
    use B;
  }

Then I would like the computation of B to be moved after the test.
This way, if the exit test succeeds, you wouldn't have computed B for nothing.

-- 
Sylvain