Speed-up 'new TypedArray(arrayLike)'.

Speed-up 'new TypedArray(arrayLike)'.

Handle specially the cases when the argument is a typed array,
in particular of the same type as the one we create.

Allocate backing store uninitialized in cases when we can guarantee
complete initialization.

R=bmeurer@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=15998

Committed: https://code.google.com/p/v8/source/detail?r=16005

[Dmitry Lomov (no reviews), 2013-07-31 14:42:45]

PTAL

[Benedikt Meurer, 2013-08-01 06:14:35]

https://codereview.chromium.org/21369002/diff/1/src/runtime.cc
File src/runtime.cc (right):

https://codereview.chromium.org/21369002/diff/1/src/runtime.cc#newcode814
src/runtime.cc:814: int arrayId, ExternalArrayType& array_type, size_t&
element_size) {
Use pointers instead of references.

https://codereview.chromium.org/21369002/diff/1/src/runtime.cc#newcode875
src/runtime.cc:875: ArrayIdToTypeAndSize(arrayId, array_type, element_size);
Pointers for 2nd and 3rd argument.

[Dmitry Lomov (no reviews), 2013-08-01 07:42:06]

On 2013/08/01 06:14:35, Benedikt Meurer wrote:
> https://codereview.chromium.org/21369002/diff/1/src/runtime.cc
> File src/runtime.cc (right):
> 
> https://codereview.chromium.org/21369002/diff/1/src/runtime.cc#newcode814
> src/runtime.cc:814: int arrayId, ExternalArrayType& array_type, size_t&
> element_size) {
> Use pointers instead of references.
> 
> https://codereview.chromium.org/21369002/diff/1/src/runtime.cc#newcode875
> src/runtime.cc:875: ArrayIdToTypeAndSize(arrayId, array_type, element_size);
> Pointers for 2nd and 3rd argument.
yeah yeah yeah stupid google style rule. I spent too much time in WebKit land
lately where you can actually use language features for what they were intended.

[Dmitry Lomov (no reviews), 2013-08-01 07:44:35]

Comments (very reluctantly) addressed.

[Benedikt Meurer, 2013-08-01 08:09:45]

LGTM

[Dmitry Lomov (no reviews), 2013-08-01 08:19:57]

Committed patchset #2 manually as r15998 (presubmit successful).

[Dmitry Lomov (no reviews), 2013-08-01 08:52:27]

Committed patchset #2 manually as r16005 (presubmit successful).