PPC: [Atomics] code stubs for atomic operations

PPC: [Atomics] code stubs for atomic operations

Port 5e9ddf6ce4b698cb3112bd349ca5206cfada1437

Original commit message:
    * New atomic code stubs for x64, ia32, arm, arm64
    * Add convenience functions JumpIfNotValidSmiValue, JumpIfUintNotValidSmiValue
      to macro-assembler-ia32 (API based on x64 macro assembler)
    * Remove runtime implementation of Atomics.load, the code stub should always be
      called instead
    * Add new test to mjsunit atomics test; check that Smi values of different
      sizes are supported when possible, else fall back to HeapNumbers

    These changes were needed to add another codestub:
    * Bump kStubMajorKeyBits from 7 to 8
    * Reduce ScriptContextFieldStub::kSlotIndexBits from 13 to 12

R=binji@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, bjaideep@ca.ibm.com
BUG=v8:4614
LOG=N

Committed: https://crrev.com/89e9819cbe0c3648a59ec9fcf328aaf3b735027d
Cr-Commit-Position: refs/heads/master@{#35462}

[MTBrandyberry, 2016-04-13 22:30:49]

PTAL

[MTBrandyberry, 2016-04-13 22:31:07]

The CQ bit was checked by mbrandy@us.ibm.com to run a CQ dry run

[commit-bot: I haz the power, 2016-04-13 22:31:10]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1887823002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1887823002/1

[binji, 2016-04-13 22:36:04]

On 2016/04/13 22:30:49, MTBrandyberry wrote:
> PTAL

Looks good, please note https://codereview.chromium.org/1883903002/ as well,
which I'll likely land soon to remove some of the extra logic from the code
stub.

[binji, 2016-04-13 22:48:13]

On 2016/04/13 22:36:04, binji wrote:
> On 2016/04/13 22:30:49, MTBrandyberry wrote:
> > PTAL
> 
> Looks good, please note https://codereview.chromium.org/1883903002/ as well,
> which I'll likely land soon to remove some of the extra logic from the code
> stub.

Also, you'd know better than I would, but I've been following the instruction
sequences defined here: https://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html;
it uses the following instruction sequence for a sequentially consistent load:

Load Seq Cst:	hwsync; ld; cmp; bc; isync

[commit-bot: I haz the power, 2016-04-13 22:49:11]

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

[commit-bot: I haz the power, 2016-04-13 22:49:12]

Dry run: This issue passed the CQ dry run.

[john.yan, 2016-04-13 23:37:54]

lgtm

[MTBrandyberry, 2016-04-14 02:01:31]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2016-04-14 02:01:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1887823002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1887823002/1

[commit-bot: I haz the power, 2016-04-14 02:03:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-14 02:05:30]

Description was changed from

==========
PPC: [Atomics] code stubs for atomic operations

Port 5e9ddf6ce4b698cb3112bd349ca5206cfada1437

Original commit message:
    * New atomic code stubs for x64, ia32, arm, arm64
    * Add convenience functions JumpIfNotValidSmiValue,
JumpIfUintNotValidSmiValue
      to macro-assembler-ia32 (API based on x64 macro assembler)
    * Remove runtime implementation of Atomics.load, the code stub should always
be
      called instead
    * Add new test to mjsunit atomics test; check that Smi values of different
      sizes are supported when possible, else fall back to HeapNumbers

    These changes were needed to add another codestub:
    * Bump kStubMajorKeyBits from 7 to 8
    * Reduce ScriptContextFieldStub::kSlotIndexBits from 13 to 12

R=binji@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com, bjaideep@ca.ibm.com
BUG=v8:4614
LOG=N
==========

to

==========
PPC: [Atomics] code stubs for atomic operations

Port 5e9ddf6ce4b698cb3112bd349ca5206cfada1437

Original commit message:
    * New atomic code stubs for x64, ia32, arm, arm64
    * Add convenience functions JumpIfNotValidSmiValue,
JumpIfUintNotValidSmiValue
      to macro-assembler-ia32 (API based on x64 macro assembler)
    * Remove runtime implementation of Atomics.load, the code stub should always
be
      called instead
    * Add new test to mjsunit atomics test; check that Smi values of different
      sizes are supported when possible, else fall back to HeapNumbers

    These changes were needed to add another codestub:
    * Bump kStubMajorKeyBits from 7 to 8
    * Reduce ScriptContextFieldStub::kSlotIndexBits from 13 to 12

R=binji@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com, bjaideep@ca.ibm.com
BUG=v8:4614
LOG=N

Committed: https://crrev.com/89e9819cbe0c3648a59ec9fcf328aaf3b735027d
Cr-Commit-Position: refs/heads/master@{#35462}
==========

[commit-bot: I haz the power, 2016-04-14 02:05:32]

Patchset 1 (id:??) landed as
https://crrev.com/89e9819cbe0c3648a59ec9fcf328aaf3b735027d
Cr-Commit-Position: refs/heads/master@{#35462}