Implement log10 via fdlibm port.

Implement log10 via fdlibm port.

R=rtoy@chromium.org
BUG=v8:3579
LOG=N

Committed: https://chromium.googlesource.com/v8/v8/+/c7def799177a10011304518bf1c230efe790e18c

[Raymond Toy, 2014-11-19 19:02:30]

lgtm with a few nits.

https://codereview.chromium.org/739913003/diff/1/src/third_party/fdlibm/fdlib...
File src/third_party/fdlibm/fdlibm.cc (right):

https://codereview.chromium.org/739913003/diff/1/src/third_party/fdlibm/fdlib...
src/third_party/fdlibm/fdlibm.cc:30: 6.36619772367581382433e-01,   // invpio2   
0
Did you insert tabs here?  Does the V8 coding style allow that?  Even if it is
allowed, that seems unnecessary for this CL.

https://codereview.chromium.org/739913003/diff/1/test/mjsunit/es6/math-log2-l...
File test/mjsunit/es6/math-log2-log10.js (right):

https://codereview.chromium.org/739913003/diff/1/test/mjsunit/es6/math-log2-l...
test/mjsunit/es6/math-log2-log10.js:43: assertEqualsDelta(i,
Math.log10(Math.pow(10, i)), 1E-16);
Nit: It would be useful to have a more accurate bound than 1e-16, in case log10
or pow changes slightly.

https://codereview.chromium.org/739913003/diff/1/test/mjsunit/es6/math-log2-l...
test/mjsunit/es6/math-log2-log10.js:51: assertEquals(-307.77759430519706,
Math.log10(1.5 * Math.pow(2, -1023)));
Add comment that you're testing a denormal case.

[Yang, 2014-11-20 09:05:11]

https://codereview.chromium.org/739913003/diff/1/src/third_party/fdlibm/fdlib...
File src/third_party/fdlibm/fdlibm.cc (right):

https://codereview.chromium.org/739913003/diff/1/src/third_party/fdlibm/fdlib...
src/third_party/fdlibm/fdlibm.cc:30: 6.36619772367581382433e-01,   // invpio2   
0
On 2014/11/19 19:02:30, Raymond Toy wrote:
> Did you insert tabs here?  Does the V8 coding style allow that?  Even if it is
> allowed, that seems unnecessary for this CL.

Merely moved by one whitespace to fit the comments for the new entries.

https://codereview.chromium.org/739913003/diff/1/test/mjsunit/es6/math-log2-l...
File test/mjsunit/es6/math-log2-log10.js (right):

https://codereview.chromium.org/739913003/diff/1/test/mjsunit/es6/math-log2-l...
test/mjsunit/es6/math-log2-log10.js:43: assertEqualsDelta(i,
Math.log10(Math.pow(10, i)), 1E-16);
On 2014/11/19 19:02:30, Raymond Toy wrote:
> Nit: It would be useful to have a more accurate bound than 1e-16, in case
log10
> or pow changes slightly.

Done.

https://codereview.chromium.org/739913003/diff/1/test/mjsunit/es6/math-log2-l...
test/mjsunit/es6/math-log2-log10.js:51: assertEquals(-307.77759430519706,
Math.log10(1.5 * Math.pow(2, -1023)));
On 2014/11/19 19:02:30, Raymond Toy wrote:
> Add comment that you're testing a denormal case.

Done.

[Yang, 2014-11-20 09:05:14]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2014-11-20 09:05:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/739913003/20001

[commit-bot: I haz the power, 2014-11-20 09:05:40]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-11-20 09:05:41]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Sven Panne, 2014-11-20 09:09:38]

svenpanne@chromium.org changed reviewers:
+ svenpanne@chromium.org

[Sven Panne, 2014-11-20 09:09:39]

LGTM (mostly rubber-stamped)

[Yang, 2014-11-20 09:09:44]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2014-11-20 09:10:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/739913003/20001

[commit-bot: I haz the power, 2014-11-20 09:37:25]

Committed patchset #2 (id:20001)