More on vectorized comparisons

bearophile bearophileHUGS at lycos.com
Fri Aug 24 06:57:41 PDT 2012


>It's just syntax sugar for a very obscure operation,<

It's an operation included in Cilk Plus, I think Intel devs know
enough what they are doing.
And I think code like this is a common need:

if (a[] > 0) {
      // ...
}


>and it's somewhat ambiguous -- is it allowed to use 
>short-circuit evaluation?<

That code means:

foreach (i; 0 .. a.length) {
      if (a[i] > 0) {
          // ...
      }
}

Here I don't see problems caused by short circuit evaluation.


>You can compare scalars, but ordered comparison of vectors is a 
>bit nonsensical, unless it is element-wise.<

It's a comparison element-wise between each item and a constant,
it's similar to:

a[] = a[] + 5;

Probably you have misunderstood the semantics of what I am
discussing.

Bye,
bearophile


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