Add SSE2/MMX build flags when building on an x86 host. This is necessary

Add SSE2/MMX build flags when building on an x86 host. This is necessary
because some files use SSE2 extensions, which may not be available on
all x86 CPUs.

BUG=607938
R=dpranke@chromium.org

Committed: https://crrev.com/bfb9e9ef5c13843e22a74a7bced0d48b6f42c112
Cr-Commit-Position: refs/heads/master@{#392206}

[Dirk Pranke, 2016-05-05 17:26:35]

dpranke@chromium.org changed reviewers:
+ thakis@chromium.org

[Dirk Pranke, 2016-05-05 17:26:36]

I'm not close enough to how these compiler flags work on different host cpus, so
I'm not sure what's the default and what needs to be explicitly set these days.

So, I'm punting this to thakis, who hopefully knows this stuff; if not, he can
re-punt.

However, ...

1) Doesn't chromium require SSE2 nowadays?

2) If we do need to change things, this change should be part of the
'compiler_cpu_abi' config, not the base config.

[Nico, 2016-05-05 17:33:23]

lgtm; from what I understand this ports
https://codereview.chromium.org/187423002 to gn

https://codereview.chromium.org/1952043003/diff/1/build/config/compiler/BUILD.gn
File build/config/compiler/BUILD.gn (right):

https://codereview.chromium.org/1952043003/diff/1/build/config/compiler/BUILD...
build/config/compiler/BUILD.gn:226: "-mmmx",
doesn't msse2 imply mmx?

[saiarcot895, 2016-05-05 21:25:18]

https://codereview.chromium.org/1952043003/diff/1/build/config/compiler/BUILD.gn
File build/config/compiler/BUILD.gn (right):

https://codereview.chromium.org/1952043003/diff/1/build/config/compiler/BUILD...
build/config/compiler/BUILD.gn:226: "-mmmx",
On 2016/05/05 at 17:33:23, Nico wrote:
> doesn't msse2 imply mmx?

It might (based on the options for the -march flag and the extensions it sets),
but it's not explicitly stated in the GCC documentation.

[saiarcot895, 2016-05-05 22:41:41]

The CQ bit was checked by saiarcot895@gmail.com

[commit-bot: I haz the power, 2016-05-05 22:42:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1952043003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1952043003/1

[commit-bot: I haz the power, 2016-05-05 23:36:25]

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

[commit-bot: I haz the power, 2016-05-05 23:36:26]

Try jobs failed on following builders:
  chromeos_x86-generic_chromium_compile_only_ng on tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_x86-ge...)

[saiarcot895, 2016-05-06 03:31:07]

PTAL. The CFLAGS addition has been moved to the compiler_cpu_abi config section,
and the code has been fixed to not add the flags when using the NaCl toolchain,
which should fix the trybot failure.

[Dirk Pranke, 2016-05-06 22:36:10]

lgtm

[Dirk Pranke, 2016-05-06 22:36:19]

The CQ bit was checked by dpranke@chromium.org

[Dirk Pranke, 2016-05-06 22:36:20]

The patchset sent to the CQ was uploaded after l-g-t-m from thakis@chromium.org
Link to the patchset: https://codereview.chromium.org/1952043003/#ps20001
(title: "Moved to compiler_cpu_abi config, and fixed for NaCl build")

[commit-bot: I haz the power, 2016-05-06 22:36:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1952043003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1952043003/20001

[Nico, 2016-05-06 22:38:54]

Hm, in the new location clang-cl won't see these flags.

[Dirk Pranke, 2016-05-06 22:45:52]

On 2016/05/06 22:38:54, Nico wrote:
> Hm, in the new location clang-cl won't see these flags.

Yup, as you no doubt know, there's a bunch of duplication between posix-y
configs and win-clang configs. I don't think fixing that is in the scope of this
particular tiny change.

[Nico, 2016-05-06 22:52:02]

This is adding flags missing in the gn build; might as well do it right (if
(is_clang or not win) and ia32)
On May 6, 2016 6:45 PM, <dpranke@chromium.org> wrote:

> On 2016/05/06 22:38:54, Nico wrote:
> > Hm, in the new location clang-cl won't see these flags.
>
> Yup, as you no doubt know, there's a bunch of duplication between posix-y
> configs and win-clang configs. I don't think fixing that is in the scope
> of this
> particular tiny change.
>
> https://codereview.chromium.org/1952043003/
>

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[commit-bot: I haz the power, 2016-05-06 23:42:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-05-06 23:44:54]

Description was changed from

==========
Add SSE2/MMX build flags when building on an x86 host. This is necessary
because some files use SSE2 extensions, which may not be available on
all x86 CPUs.

BUG=607938
R=dpranke@chromium.org
==========

to

==========
Add SSE2/MMX build flags when building on an x86 host. This is necessary
because some files use SSE2 extensions, which may not be available on
all x86 CPUs.

BUG=607938
R=dpranke@chromium.org

Committed: https://crrev.com/bfb9e9ef5c13843e22a74a7bced0d48b6f42c112
Cr-Commit-Position: refs/heads/master@{#392206}
==========

[commit-bot: I haz the power, 2016-05-06 23:44:55]

Patchset 2 (id:??) landed as
https://crrev.com/bfb9e9ef5c13843e22a74a7bced0d48b6f42c112
Cr-Commit-Position: refs/heads/master@{#392206}