1296642 - avoid compiling {Read,Write}Sentinel calls in non-sentinel checking builds

Status: RESOLVED FIXED

(Core :: IPC, defect)

Description

[Nathan Froyd [:froydnj]]

Pickle::{Read,Write}Sentinel were introduced as a way of catching
problems with corrupted IPDL messages at the point of message
serialization, rather than the point of use of the bad data.  The
checking itself is only done on debug or non-release builds, but the
calls to the functions are compiled in regardless of whether checking is
done.  While LTO could plausibly optimize away all the calls, we don't
have LTO on all of our platforms, particularly mobile.  Therefore, we
should move the non-checking versions of the calls inline, so the
compiler can eliminate those calls entirely, even in non-LTO builds.

Comment 1

[Nathan Froyd [:froydnj]]

Attachment: avoid compiling {Read,Write}Sentinel calls in non-sentinel checking builds

This change saves ~280K of .text on x86-64 Linux.

Comment 2

[Nathan Froyd [:froydnj]]

[Tracking Requested - why for this release]: This is a decent-sized size regression, which is particularly important for our Android builds.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/9140ec44d27b
avoid compiling {Read,Write}Sentinel calls in non-sentinel checking builds; r=billm

Comment 4

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/9140ec44d27b

Comment 5

[Nathan Froyd [:froydnj]]

Comment on attachment 8782932 [details] [diff] [review]
avoid compiling {Read,Write}Sentinel calls in non-sentinel checking builds

Approval Request Comment
[Feature/regressing bug #]: bug 1262671
[User impact if declined]: larger binaries, slightly worse performance
[Describe test coverage new/current, TreeHerder]: e10s tests run this code pretty comprehensively.
[Risks and why]: This is a low-risk patch; it's essentially restoring us to the same code we produce on the 48 branch, and eliminating a few no-op function calls.
[String/UUID change made/needed]: none

Comment 6

[Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)]

Comment on attachment 8782932 [details] [diff] [review]
avoid compiling {Read,Write}Sentinel calls in non-sentinel checking builds

Recent regression, let's uplift to Aurora50, has stabilized on Nightly for a few days.

Comment 7

[Liz Henry (:lizzard) (relman/hg->git project)]

Comment on attachment 8782932 [details] [diff] [review]
avoid compiling {Read,Write}Sentinel calls in non-sentinel checking builds

Fix for regression from 49, let's uplift this for beta 7.

Comment 8

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/8a0abccd9563

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/ffd7ae9b354a