geofflang: Possible feature for MANGLE?

Don't think it needs to fall under the MANGLE project but this is certainly an optimization we could attempt.

It might be possible to bake it in the ANGLE_TRY macros, although we need to be careful that it can regress performance of unpredictable branches. I also thought clang had a function attribute to say that calling the function was unlikely, which we could have used on one of Error's constructors. I didn't find it though.

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Now that we're on clang everywhere, maybe we should reprioritize this?

Yes, this is much more doable now that we're on clang everywhere. ANGLE's error generation is wrapped in a macro so adding it should be easy.

The following revision refers to this bug:
  https://chromium.googlesource.com/angle/angle/+/7b19a49bc53e407cf18e721a809271cbcc422e42

commit 7b19a49bc53e407cf18e721a809271cbcc422e42
Author: Geoff Lang <geofflang@chromium.org>
Date: Fri Apr 20 17:06:08 2018

Use LIKELY and UNLIKELY macros to wrap error generation.

BUG= 609673 

Change-Id: I247f561712e30aa10bad77fabf614501d596915e
Reviewed-on: https://chromium-review.googlesource.com/1021995
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>

[modify] https://crrev.com/7b19a49bc53e407cf18e721a809271cbcc422e42/src/libANGLE/Context.cpp
[modify] https://crrev.com/7b19a49bc53e407cf18e721a809271cbcc422e42/src/libANGLE/renderer/vulkan/vk_utils.h
[modify] https://crrev.com/7b19a49bc53e407cf18e721a809271cbcc422e42/src/libANGLE/Error.h
[modify] https://crrev.com/7b19a49bc53e407cf18e721a809271cbcc422e42/src/common/platform.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/90e886d1638437a1346367e36bbff675a826fe66

commit 90e886d1638437a1346367e36bbff675a826fe66
Author: angle-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com <angle-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Fri Apr 20 23:32:04 2018

Roll src/third_party/angle/ 3ec304dba..5f21df831 (8 commits)

https://chromium.googlesource.com/angle/angle.git/+log/3ec304dba28d..5f21df8318e9

$ git log 3ec304dba..5f21df831 --date=short --no-merges --format='%ad %ae %s'
2018-04-18 tobine Roll (1/2) LVL version forward and disable VANGLE
2018-04-19 ynovikov Use EGL_KHR_no_config_context in Android GLES backend, when available
2018-04-20 ynovikov Print more logs
2018-04-10 geofflang Refactor packed enum generation to support EGL enums.
2018-04-20 geofflang Use LIKELY and UNLIKELY macros to wrap error generation.
2018-04-20 jmadill Fix WebGL compat feedback loop null deref.
2018-04-19 tobine Make Mock ICD json file a data_dep of Mock ICD
2018-04-19 lucferron Refactor Texture::syncState to pass down the Context

Created with:
  roll-dep src/third_party/angle
BUG= chromium:609673 , chromium:834943 


The AutoRoll server is located here: https://angle-chromium-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
TBR=jmadill@chromium.org

Change-Id: Ifbfe7a6eec5c1771a9ecf20a9cd31f5070758588
Reviewed-on: https://chromium-review.googlesource.com/1022720
Reviewed-by: angle-chromium-autoroll <angle-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: angle-chromium-autoroll <angle-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#552520}
[modify] https://crrev.com/90e886d1638437a1346367e36bbff675a826fe66/DEPS

Implemented but didn't see any perf change so I'm not going to peruse using it in any more parts of ANGLE's code for now.