The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/cf253f786e2c0a37ca1316f2fc2e9ed6ecdca9b8

commit cf253f786e2c0a37ca1316f2fc2e9ed6ecdca9b8
Author: Yunlian Jiang <yunlian@google.com>
Date: Thu Jun 21 04:45:48 2018

Disable thinlto on ARM board.

We cannot generate the .dwp file for chrome on arm consistently. So we
have to disable thinlto for now.

BUG= chromium:854801 
TEST=equery-daisy u chromeos-chrome does not show thinlto

Change-Id: I48e857b00b09e44339539aeb211eb9d66e1703e8
Reviewed-on: https://chromium-review.googlesource.com/1109411
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Trybot-Ready: Yunlian Jiang <yunlian@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>

[modify] https://crrev.com/cf253f786e2c0a37ca1316f2fc2e9ed6ecdca9b8/profiles/arch/arm/package.use.mask

Incidental: we've noticed a 7% boost for Speedometer with thinlto turned on on Arm boards, so it's important to get this working right...

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/1b45f0dc972b5fa057806027d9807523ad543b4c

commit 1b45f0dc972b5fa057806027d9807523ad543b4c
Author: Yunlian Jiang <yunlian@google.com>
Date: Tue Jun 26 23:35:04 2018

remove USE=thinlto from elm and peach_pit release

Since we could not get .dwp file consistently because of thinlto,
we want to disable USE=thinlto for now.

BUG= chromium:854801 
TEST=runtest.

Change-Id: I70b3223f6f3a8920f54f5f76c77625862505ced6
Reviewed-on: https://chromium-review.googlesource.com/1115723
Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>

[modify] https://crrev.com/1b45f0dc972b5fa057806027d9807523ad543b4c/config/chromeos_config.py
[modify] https://crrev.com/1b45f0dc972b5fa057806027d9807523ad543b4c/config/config_dump.json

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4b12fd08203253e41b08793e8a9527d6942d04e1

commit 4b12fd08203253e41b08793e8a9527d6942d04e1
Author: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Wed Jun 27 01:32:25 2018

Roll src/third_party/chromite a481ed6f083d..1b45f0dc972b (1 commits)

https://chromium.googlesource.com/chromiumos/chromite.git/+log/a481ed6f083d..1b45f0dc972b


git log a481ed6f083d..1b45f0dc972b --date=short --no-merges --format='%ad %ae %s'
2018-06-26 yunlian@google.com remove USE=thinlto from elm and peach_pit release


Created with:
  gclient setdep -r src/third_party/chromite@1b45f0dc972b

The AutoRoll server is located here: https://chromite-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.



BUG= chromium:854801 
TBR=chrome-os-gardeners@chromium.org

Change-Id: Iaf752b79eead83599902e5bdb3bf9a2b81620527
Reviewed-on: https://chromium-review.googlesource.com/1115978
Reviewed-by: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#570615}
[modify] https://crrev.com/4b12fd08203253e41b08793e8a9527d6942d04e1/DEPS

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/d70a80f7a44548cc500bf7cb3130fdc3172b520a

commit d70a80f7a44548cc500bf7cb3130fdc3172b520a
Author: Yunlian Jiang <yunlian@google.com>
Date: Thu Jun 28 05:07:23 2018

chromeos-chrome: force to die if command 'dwp' fails.

We found that sometimes the .dwp files were missing from the debug
directory. This is because the command 'dwp' failed to generate the
.dwp files. In this case, we should stop the build and let the user
know something is wrong there.

BUG= chromium:854801 
TEST=emerge-chrome dies if 'dwp' is failed.

Change-Id: I8996c8131c4b471ef19640b1dd0981b19014e57e
Reviewed-on: https://chromium-review.googlesource.com/1114070
Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/d70a80f7a44548cc500bf7cb3130fdc3172b520a/chromeos-base/chromeos-chrome/chromeos-chrome-9999.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/40f8d2099be1b51182bc5eeee8f4aa628ef068be

commit 40f8d2099be1b51182bc5eeee8f4aa628ef068be
Author: Yunlian Jiang <yunlian@google.com>
Date: Thu Jun 28 05:07:19 2018

profile: clean USE="thinlto" on arm board.

We enabled thinlto on ARM and we reverted it because of debug file
issue. Now chrome uprevs and we can clean USE="thinlto" on arm board for
now.

BUG= chromium:854801 
TEST=None

Change-Id: I4c5a7609935be904f5a3ee7d3214268f1001ce5b
Reviewed-on: https://chromium-review.googlesource.com/1115733
Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>

[modify] https://crrev.com/40f8d2099be1b51182bc5eeee8f4aa628ef068be/profiles/arch/arm/package.use.mask
[delete] https://crrev.com/7bc214b120f845e4b713dc2094e18af43756ce95/profiles/arch/arm/package.use

This is a side effect of  crbug.com/855086 .
The root cause of the error looks like this:

When linking chrome with thinlto and debug fission, it generates
final binary and a directory DIR which contains a set of .dwo files.

After the link stage, we use command 'dwp' to generate '.dwp' file,
After that, we remove the 'DIR' and all the .dwo files.

In the later preinst stage, it checks the file size in the debug directory
to make sure that all the files are less than 4 GiB. Because of the bug
 crbug.com/855086 , the emerge command failed with message 'file chrome.dwp
exceeds 4GB'

The build_package stage allows the failed package to build again to fix potential dependency problem. In this case, it tries to build chrome again.
This time, it wouldn't build anything because all the object files and final binaries are still there. Because we removed the directory DIR that contains the the .dwo files, the command 'dwp' would not generate any .dwp files. This time, chrome builds fine but no .dwp file was generated.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/7dd88fc7ddb42f1d9fbb80ae428156eb2e90a23b

commit 7dd88fc7ddb42f1d9fbb80ae428156eb2e90a23b
Author: Yunlian Jiang <yunlian@google.com>
Date: Fri Jun 29 20:29:39 2018

Enable ThinLTO on all ARM boards.

We have enabled ThinLTO on elm and peach_pit in R68 and so
far so good. This CL enables ThinLTO on all ARM boards.

We enabled this feature via CL:1095415 but it got reverted because
of chromium:854801. We believe that we have identified the root
cause and fixed the problem.

BUG= chromium:827217   chromium:854801 
TEST=cros tryjob daisy-release

Change-Id: I3a440f2faeff7c4ffa5a1117040f20ef21b63af0
Reviewed-on: https://chromium-review.googlesource.com/1120944
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>

[add] https://crrev.com/7dd88fc7ddb42f1d9fbb80ae428156eb2e90a23b/profiles/arch/arm/package.use

This bug has an owner, thus, it's been triaged. Changing status to "assigned".