[x86] Blacklist AVX for Windows versions before 6.1 (Windows 7).

[x86] Blacklist AVX for Windows versions before 6.1 (Windows 7).

BUG=v8:3846
LOG=y

Committed: https://crrev.com/65299cf463b054b10b1b4a6709590019d05433aa
Cr-Commit-Position: refs/heads/master@{#26239}

[Benedikt Meurer, 2015-01-23 08:38:07]

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

[Benedikt Meurer, 2015-01-23 08:38:08]

PTAL

[Sven Panne, 2015-01-23 08:40:47]

LGTM, hope it helps. :)

[Weiliang, 2015-01-23 08:43:36]

On 2015/01/23 08:40:47, Sven Panne wrote:
> LGTM, hope it helps. :)

Well, we may need to introduce the AVX version instruction for legacy SSE
instruction.

[Benedikt Meurer, 2015-01-23 08:46:26]

> Well, we may need to introduce the AVX version instruction for legacy SSE
instruction.

You mean that would solve the issue? What about code generated by MSVC? This
code will still use the SSE instructions.

[Benedikt Meurer, 2015-01-23 08:46:45]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-01-23 08:46:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/869133002/1

[Weiliang, 2015-01-23 08:58:54]

On 2015/01/23 08:46:26, Benedikt Meurer wrote:
> > Well, we may need to introduce the AVX version instruction for legacy SSE
> instruction.
> 
> You mean that would solve the issue? What about code generated by MSVC? This
> code will still use the SSE instructions.

Yes, at least for the JIT code. 

I think MSVC generated either all vex version instruction if available or all
legacy sse instruction. 

Currently in V8, only part sse instruction supports vex version, which supports
non-destrutive operand. 

The only issue for v8 is that the precompiled code in snapshot can only use the
legacy version, but the JIT may be vex version or legacy version, depending on
the target platform.

[Benedikt Meurer, 2015-01-23 09:01:37]

On 2015/01/23 at 08:58:54, weiliang.lin wrote:
> On 2015/01/23 08:46:26, Benedikt Meurer wrote:
> > > Well, we may need to introduce the AVX version instruction for legacy SSE
> > instruction.
> > 
> > You mean that would solve the issue? What about code generated by MSVC? This
> > code will still use the SSE instructions.
> 
> Yes, at least for the JIT code. 
> 
> I think MSVC generated either all vex version instruction if available or all
legacy sse instruction. 
> 
> Currently in V8, only part sse instruction supports vex version, which
supports non-destrutive operand. 
> 
> The only issue for v8 is that the precompiled code in snapshot can only use
the legacy version, but the JIT may be vex version or legacy version, depending
on the target platform.

Sounds good if that helps to fix the problem. However for 4.1 we will just
disable AVX on older windows versions for now.

[commit-bot: I haz the power, 2015-01-23 09:16:37]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-23 09:16:54]

Patchset 1 (id:??) landed as
https://crrev.com/65299cf463b054b10b1b4a6709590019d05433aa
Cr-Commit-Position: refs/heads/master@{#26239}