V8: Add utility functions to check SameValue and SameValueZero.

V8: Add utility functions to check SameValue and SameValueZero.
Adds SameValue and SameValueZero functions for float and double.
These will be used for HeapNumber and SIMD values.

LOG=N
BUG=v8:4124
Committed: https://crrev.com/ed898473cfadcb8b3b5b0c776a56d4a2513f5317
Cr-Commit-Position: refs/heads/master@{#29660}

[Dan Ehrenberg, 2015-07-14 18:15:18]

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

[Dan Ehrenberg, 2015-07-14 18:15:18]

+1 makes sense to me, but I don't know this code so well.

[bbudge, 2015-07-14 18:18:48]

bbudge@chromium.org changed reviewers:
+ jochen@chromium.org

[bbudge, 2015-07-14 18:18:48]

Will be used in https://codereview.chromium.org/1219943002/

[adamk, 2015-07-14 18:26:57]

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

[adamk, 2015-07-14 18:26:58]

Where are the other callers going to live? My only concern with this is that
utils.h is currently pretty JS-agnostic (which is why I suggested adding
comments pointing to the spec, to make it clear these are for spec compliance).

https://codereview.chromium.org/1234073003/diff/20001/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1234073003/diff/20001/src/objects.cc#newcode686
src/objects.cc:686: return v8::internal::SameValue(Number(), other->Number());
Why the "v8::internal::" prefix here? Does this fail to lookup properly without
it?

https://codereview.chromium.org/1234073003/diff/20001/src/utils.h
File src/utils.h (right):

https://codereview.chromium.org/1234073003/diff/20001/src/utils.h#newcode205
src/utils.h:205: bool SameValue(T x, T y) {
Can you add a comment linking to:

http://www.ecma-international.org/ecma-262/6.0/#sec-samevalue

https://codereview.chromium.org/1234073003/diff/20001/src/utils.h#newcode215
src/utils.h:215: bool SameValueZero(T x, T y) {
And here linking to:

http://www.ecma-international.org/ecma-262/6.0/#sec-samevaluezero

[bbudge, 2015-07-14 20:26:24]

This will be used in the SIMD value type tests for SameValue and SameValueZero,
in objects.cc and in the runtime-simd.cc implementation of new intrinsics that
implement used by SameValue and SameValueZero in runtime.js.

utils.h seemed like a good place to put this but I'm open to other suggestions.

https://codereview.chromium.org/1234073003/diff/20001/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1234073003/diff/20001/src/objects.cc#newcode686
src/objects.cc:686: return v8::internal::SameValue(Number(), other->Number());
On 2015/07/14 18:26:58, adamk wrote:
> Why the "v8::internal::" prefix here? Does this fail to lookup properly
without
> it?

Without the prefix, it tries to match to an Object:: overload, which doesn't
exist. I could change the name to same_value but this seems more consistent with
the existing math functions in utils.h.

https://codereview.chromium.org/1234073003/diff/20001/src/utils.h
File src/utils.h (right):

https://codereview.chromium.org/1234073003/diff/20001/src/utils.h#newcode205
src/utils.h:205: bool SameValue(T x, T y) {
On 2015/07/14 18:26:58, adamk wrote:
> Can you add a comment linking to:
> 
> http://www.ecma-international.org/ecma-262/6.0/#sec-samevalue

Done.

https://codereview.chromium.org/1234073003/diff/20001/src/utils.h#newcode215
src/utils.h:215: bool SameValueZero(T x, T y) {
On 2015/07/14 18:26:58, adamk wrote:
> And here linking to:
> 
> http://www.ecma-international.org/ecma-262/6.0/#sec-samevaluezero

Done.

[adamk, 2015-07-14 20:39:03]

The CQ bit was checked by adamk@chromium.org

[adamk, 2015-07-14 20:39:03]

lgtm

[commit-bot: I haz the power, 2015-07-14 20:39:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1234073003/40001

[commit-bot: I haz the power, 2015-07-14 21:35:57]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-07-14 21:36:16]

Patchset 3 (id:??) landed as
https://crrev.com/ed898473cfadcb8b3b5b0c776a56d4a2513f5317
Cr-Commit-Position: refs/heads/master@{#29660}