Harmony: implement Math.cbrt, Math.expm1 and Math.log1p.

Harmony: implement Math.cbrt, Math.expm1 and Math.log1p.

BUG=v8:2938
LOG=N
R=jarin@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19486

[Yang, 2014-02-14 10:18:22]

Please take a look.

[Jarin, 2014-02-18 14:08:53]

lgtm with nits

https://codereview.chromium.org/163563003/diff/30001/src/harmony-math.js
File src/harmony-math.js (right):

https://codereview.chromium.org/163563003/diff/30001/src/harmony-math.js#newc...
src/harmony-math.js:160: if (x === 0 || !NUMBER_IS_FINITE(x)) return x;
Is there any reason why you check for the corner cases for MathCbrt, but not for
the other functions? (runtime.cc seems to do the same checks.)

https://codereview.chromium.org/163563003/diff/30001/src/runtime.cc
File src/runtime.cc (right):

https://codereview.chromium.org/163563003/diff/30001/src/runtime.cc#newcode7678
src/runtime.cc:7678: p_approx[1] = p_x[1] / 3 + 715094163;  // magic number.
Nit: could you make this more friendly to big endian?

I am thinking:

  uint32_t xhigh = (uint32_t)(*(uint64_t*)&x >> 32);
  uint32_t approxhigh = xhigh / 3 + 715094163;
  *((uint64_t*)&approx) = (uint64_t)approxhigh << 32;

[Jarin, 2014-02-19 13:36:39]

On 2014/02/18 14:08:53, jarin wrote:
> lgtm with nits
> 
> https://codereview.chromium.org/163563003/diff/30001/src/harmony-math.js
> File src/harmony-math.js (right):
> 
>
https://codereview.chromium.org/163563003/diff/30001/src/harmony-math.js#newc...
> src/harmony-math.js:160: if (x === 0 || !NUMBER_IS_FINITE(x)) return x;
> Is there any reason why you check for the corner cases for MathCbrt, but not
for
> the other functions? (runtime.cc seems to do the same checks.)
> 
> https://codereview.chromium.org/163563003/diff/30001/src/runtime.cc
> File src/runtime.cc (right):
> 
>
https://codereview.chromium.org/163563003/diff/30001/src/runtime.cc#newcode7678
> src/runtime.cc:7678: p_approx[1] = p_x[1] / 3 + 715094163;  // magic number.
> Nit: could you make this more friendly to big endian?
> 
> I am thinking:
> 
>   uint32_t xhigh = (uint32_t)(*(uint64_t*)&x >> 32);
>   uint32_t approxhigh = xhigh / 3 + 715094163;
>   *((uint64_t*)&approx) = (uint64_t)approxhigh << 32;

Thanks, the updated patch looks great.

[Yang, 2014-02-19 13:50:11]

Committed patchset #2 manually as r19486 (presubmit successful).