disable SSSE3 optimization for android x86 only

disable SSSE3 optimization for android x86 only

[james.wei, 2012-05-14 05:19:14]

TomH, 

I includes more condition check to ensure that only android x86 build will
disable SSSE3 optimization. 

I suppose it will not impact any other platforms as I added #if
!defined(SK_BUILD_FOR_ANDROID_NDK). 

could you help to review it? thanks

[TomH, 2012-05-14 13:32:26]

__SSSE3__ is not defined on Windows or Linux (I haven't personally checked Mac,
but I don't believe it's defined there).

[james.wei, 2012-05-14 13:38:05]

On 2012/05/14 13:32:26, TomH wrote:
> __SSSE3__ is not defined on Windows or Linux (I haven't personally checked
Mac,
> but I don't believe it's defined there).

I see. thanks for the explanation. 

so i used  !defined(SK_BUILD_FOR_ANDROID_NDK) to let other platforms except
android to enable that piece of SSSE3 code, is it ok? thanks

[TomH, 2012-05-15 15:50:28]

djsollen@ points out that SK_BUILD_FOR_ANDROID_NDK is more restrictive than
SK_BUILD_FOR_ANDROID, and we probably want the broader #define.
But I'm not confident that __SSSE3__ will be #defined on Android platforms that
have it, either, since in email we discussed how you only got it on e.g. Linux
with the -march=native compiler flag, which isn't part of the standard build
process.

Could we fix this in the gyp files by passing in -DSSSE3 on most architectures,
and not passing that in on Android? As it is we're having to pass -msse2 (and I
assume -mssse3); we ought to be able to hook on those points?

[james.wei, 2012-05-16 09:55:23]

On 2012/05/15 15:50:28, TomH wrote:
> djsollen@ points out that SK_BUILD_FOR_ANDROID_NDK is more restrictive than
> SK_BUILD_FOR_ANDROID, and we probably want the broader #define.
> But I'm not confident that __SSSE3__ will be #defined on Android platforms
that
> have it, either, since in email we discussed how you only got it on e.g. Linux
> with the -march=native compiler flag, which isn't part of the standard build
> process.
> 
> Could we fix this in the gyp files by passing in -DSSSE3 on most
architectures,
> and not passing that in on Android? As it is we're having to pass -msse2 (and
I
> assume -mssse3); we ought to be able to hook on those points?

tom, as SSSE3 instruction set is optional on part of x86/x64 platforms, I
suspect that we cannot use -DSSSE3 in gyp files for all x86/x64 platforms. 

actually, the CPU on Intel Android Phone does support SSSE3 instruction set, but
per Google's request, it is not enabled in ABI. 

as stated in ndk docs/CPU-ARCH-ABIS.html
 The ABI does *not* include any other optional IA-32 instruction set
  extension, including, but not limited to:

  - the MOVBE instruction
  - the SSSE3 "supplemental SSE3" extension
  - any variant of "SSE4"

So could I just use #if !defined(SK_BUILD_FOR_ANDROID) to fix this issue while
not impacting other platforms?

[TomH, 2012-05-16 13:26:40]

After talking to Derek, we're ready to try #if !defined(SK_BUILD_FOR_ANDROID).
I'll get that committed today.

[DerekS, 2012-05-16 13:27:35]

After talking with Tom, I'm good with giving this the green light provided that
we update the #define to SK_BUILD_FOR_ANDROID.

[james.wei, 2012-05-16 13:33:04]

tom and djsollen, 

thanks a lot for your suggestion. I have updated the patch. thanks

[DerekS, 2012-05-16 13:37:49]

On 2012/05/16 13:33:04, james.wei wrote:
> tom and djsollen, 
> 
> thanks a lot for your suggestion. I have updated the patch. thanks

LGTM

[TomH, 2012-05-16 14:24:50]

Committed with r3970; please close the issue when you get a chance.

[james.wei, 2012-05-16 21:42:15]

On 2012/05/16 14:24:50, TomH wrote:
> Committed with r3970; please close the issue when you get a chance.

thanks a lot for your help. close it.