Handle NaN value storing in Uint8Clamped typed arrays.

Handle NaN value storing in Uint8Clamped typed arrays.

TEST=mjsunit/external-array
BUG=
R=dslomov@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=24766

[dusmil.imgtec, 2014-10-21 09:39:20]

dusan.milosavljevic@imgtec.com changed reviewers:
+ akos.palfi@imgtec.com, balazs.kilvady@imgtec.com, danno@chromium.org,
jkummerow@chromium.org, paul.lind@imgtec.com, yangguo@chromium.org

[dusmil.imgtec, 2014-10-21 09:41:05]

dusan.milosavljevic@imgtec.com changed reviewers:
+ dslomov@chromium.org

[Dmitry Lomov (no reviews), 2014-10-21 10:35:37]

Is there a test for this specific issue? If not, please add one.

https://codereview.chromium.org/667113002/diff/1/src/objects-inl.h
File src/objects-inl.h (right):

https://codereview.chromium.org/667113002/diff/1/src/objects-inl.h#newcode4174
src/objects-inl.h:4174: if (!(value > 0)) return 0;
Please add comment here explaining that this is for NaNs

[dusmil.imgtec, 2014-10-21 10:53:15]

The test mjsunit/external-array already has excellent coverage.

The problem was undetected on other arches than MIPS because
return value of lrint() function is unspecified for NaN Value. 

Luckily on Arm and x86 lrint() is returning 0 which is expected
for Uint8Clamped arrays.

[dusmil.imgtec, 2014-10-21 10:53:29]

https://codereview.chromium.org/667113002/diff/1/src/objects-inl.h
File src/objects-inl.h (right):

https://codereview.chromium.org/667113002/diff/1/src/objects-inl.h#newcode4174
src/objects-inl.h:4174: if (!(value > 0)) return 0;
On 2014/10/21 10:35:37, Dmitry Lomov (chromium) wrote:
> Please add comment here explaining that this is for NaNs

Done.

[Dmitry Lomov (no reviews), 2014-10-21 11:03:26]

On 2014/10/21 10:53:15, dusmil.imgtec wrote:
> The test mjsunit/external-array already has excellent coverage.
> 
> The problem was undetected on other arches than MIPS because
> return value of lrint() function is unspecified for NaN Value. 
> 
> Luckily on Arm and x86 lrint() is returning 0 which is expected
> for Uint8Clamped arrays.

Got it, thanks!

lgtm

[dusmil.imgtec, 2014-10-21 11:11:14]

Committed patchset #2 (id:20001) manually as 24766 (presubmit successful).