Enable correct optimized double modulo operation. (TODO: enable remainder optimization).

Enable correct optimized double modulo operation. (TODO: enable remainder optimization).
Committed: https://code.google.com/p/dart/source/detail?r=17859

[Vyacheslav Egorov (Google), 2013-01-30 01:21:21]

https://codereview.chromium.org/12082063/diff/6001/runtime/vm/intermediate_la...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/12082063/diff/6001/runtime/vm/intermediate_la...
runtime/vm/intermediate_language.cc:2723:
static_cast<BinaryMathCFunction>(&fmod)), 0, true);
How about declaring C function:

double modulo(double left, double right) {
  double remainder = fmod_ieee(left, right);
  if (remainder == 0.0) {
    // We explicitely switch to the positive 0.0 (just in case it was negative).
    remainder = +0.0;
  } else if (remainder < 0) {
    if (right < 0) {
      remainder -= right;
    } else {
      remainder += right;
    }
  }
  return remainder;
}

and use it here and in Double_modulo?

This way we avoid hand written assembly altogether and guarantee that
Double_modulo native and optimized code is in sync.

[srdjan, 2013-01-30 17:25:07]

PTAL

https://codereview.chromium.org/12082063/diff/6001/runtime/vm/intermediate_la...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/12082063/diff/6001/runtime/vm/intermediate_la...
runtime/vm/intermediate_language.cc:2723:
static_cast<BinaryMathCFunction>(&fmod)), 0, true);
Excellent! Done.

On 2013/01/30 01:21:21, Vyacheslav Egorov (Google) wrote:
> How about declaring C function:
> 
> double modulo(double left, double right) {
>   double remainder = fmod_ieee(left, right);
>   if (remainder == 0.0) {
>     // We explicitely switch to the positive 0.0 (just in case it was
negative).
>     remainder = +0.0;
>   } else if (remainder < 0) {
>     if (right < 0) {
>       remainder -= right;
>     } else {
>       remainder += right;
>     }
>   }
>   return remainder;
> }
> 
> and use it here and in Double_modulo?
> 
> This way we avoid hand written assembly altogether and guarantee that
> Double_modulo native and optimized code is in sync.

[Vyacheslav Egorov (Google), 2013-01-30 17:26:20]

lgtm