Mixing-up LTO and non-LTO compile units might cause the link-time optimizer to infer wrong conclusion that some class hierarchies with internal visibility are smaller than they are (since it won't see them in the native object files from non-LTO compilation units), and then generate invalid vtables and/or virtual calls. That certainly depends on the real flags passed to a compiler, and Peter might correct / extend my examples.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c266bec7641b1926f65d1f48614aafb2008a7c57

commit c266bec7641b1926f65d1f48614aafb2008a7c57
Author: dpranke <dpranke@chromium.org>
Date: Mon Jun 20 23:22:34 2016

Add a dedicated "optimize_speed" config to GN.

The various GN configs to select different optimization levels are
confusing, and sorting them out will take a decent amount of
perf testing, but in order to achieve parity w/ GYP, for now
we need a dedicated config to make sure some components (e.g., v8)
are compiled w/ -O3 where appropriate.

R=brettw@chromium.org, machenbach@chromium.org
BUG= 616031 , 618678, 621335

Review-Url: https://codereview.chromium.org/2078223002
Cr-Commit-Position: refs/heads/master@{#400828}

[modify] https://crrev.com/c266bec7641b1926f65d1f48614aafb2008a7c57/build/config/compiler/BUILD.gn
[modify] https://crrev.com/c266bec7641b1926f65d1f48614aafb2008a7c57/third_party/opus/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2bb3c4f7a7c7632afe1b63a19d49daa61bbfc37b

commit 2bb3c4f7a7c7632afe1b63a19d49daa61bbfc37b
Author: huapengl <huapengl@amazon.com>
Date: Tue Jul 19 17:19:10 2016

Use "-Os" for Android or IOS in "optimize_max" config

Using "-Os" would benefit both Android and IOS build, because "-Os" does
"-O2" optimizations and code size improvement.

libchrome.so drops from 44MB to 42 MB.
ChromePublic.apk drops from 47 MB to 45 MB.

BUG=621335

Review-Url: https://codereview.chromium.org/2158053002
Cr-Commit-Position: refs/heads/master@{#406304}

[modify] https://crrev.com/2bb3c4f7a7c7632afe1b63a19d49daa61bbfc37b/build/config/compiler/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8f5987c15bd03c5da97aa27103d36c5943e78259

commit 8f5987c15bd03c5da97aa27103d36c5943e78259
Author: huapengl <huapengl@amazon.com>
Date: Wed Jul 20 16:08:49 2016

Revert of Use "-Os" for Android or IOS in "optimize_max" config (patchset #1 id:1 of https://codereview.chromium.org/2158053002/ )

Reason for revert:
8.1% regression in speedometer at 406285:406306

https://bugs.chromium.org/p/chromium/issues/detail?id=629798#c4

Original issue's description:
> Use "-Os" for Android or IOS in "optimize_max" config
>
> Using "-Os" would benefit both Android and IOS build, because "-Os" does
> "-O2" optimizations and code size improvement.
>
> libchrome.so drops from 44MB to 42 MB.
> ChromePublic.apk drops from 47 MB to 45 MB.
>
> BUG=621335
>
> Committed: https://crrev.com/2bb3c4f7a7c7632afe1b63a19d49daa61bbfc37b
> Cr-Commit-Position: refs/heads/master@{#406304}

TBR=dpranke@chromium.org,sdefresne@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=621335

Review-Url: https://codereview.chromium.org/2164973002
Cr-Commit-Position: refs/heads/master@{#406569}

[modify] https://crrev.com/8f5987c15bd03c5da97aa27103d36c5943e78259/build/config/compiler/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8f5987c15bd03c5da97aa27103d36c5943e78259

commit 8f5987c15bd03c5da97aa27103d36c5943e78259
Author: huapengl <huapengl@amazon.com>
Date: Wed Jul 20 16:08:49 2016

Revert of Use "-Os" for Android or IOS in "optimize_max" config (patchset #1 id:1 of https://codereview.chromium.org/2158053002/ )

Reason for revert:
8.1% regression in speedometer at 406285:406306

https://bugs.chromium.org/p/chromium/issues/detail?id=629798#c4

Original issue's description:
> Use "-Os" for Android or IOS in "optimize_max" config
>
> Using "-Os" would benefit both Android and IOS build, because "-Os" does
> "-O2" optimizations and code size improvement.
>
> libchrome.so drops from 44MB to 42 MB.
> ChromePublic.apk drops from 47 MB to 45 MB.
>
> BUG=621335
>
> Committed: https://crrev.com/2bb3c4f7a7c7632afe1b63a19d49daa61bbfc37b
> Cr-Commit-Position: refs/heads/master@{#406304}

TBR=dpranke@chromium.org,sdefresne@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=621335

Review-Url: https://codereview.chromium.org/2164973002
Cr-Commit-Position: refs/heads/master@{#406569}

[modify] https://crrev.com/8f5987c15bd03c5da97aa27103d36c5943e78259/build/config/compiler/BUILD.gn

Just FYI: This commit + revert also coincides with a ~1-2MB drop in memory usage (overall pss). After the revert memory measurements appear to have returned to their baseline: https://chromeperf.appspot.com/report?sid=299508ce2a28f86977fc0a89ee4b11c396b6abd6543aaec28f0ed77a4dbc63cf&start_rev=406005&end_rev=406744

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available. If you change it back, also remove the "Hotlist-Recharge-Cold" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot