iSAC fix entropy coder: Recently added DCHECK could in fact trigger

iSAC fix entropy coder: Recently added DCHECK could in fact trigger

A DCHECK added in a recent bugfix, which asserted that a signed 64->32
bit cast did not overflow, has been found to not always pass. We fix
this by saturating.

BUG=chromium:693868
Review-Url: https://codereview.webrtc.org/2746903002
Cr-Commit-Position: refs/heads/master@{#17209}
Committed: https://chromium.googlesource.com/external/webrtc/+/a1896a649c9238af281a0e73dacbf981d0bc8e64

[kwiberg-webrtc, 2017-03-13 09:47:28]

The CQ bit was checked by kwiberg@webrtc.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-13 09:47:33]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-03-13 09:53:03]

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

[commit-bot: I haz the power, 2017-03-13 09:53:03]

Dry run: Try jobs failed on following builders:
  ios_rel on master.tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/ios_rel/builds/22555)

[kwiberg-webrtc, 2017-03-13 09:53:40]

kwiberg@webrtc.org changed reviewers:
+ henrik.lundin@webrtc.org

[kwiberg-webrtc, 2017-03-13 09:53:41]

PTAL. I decided to saturate rather than truncate after all, because I'm
squeamish.

(The method of saturation gives branch free code with -O2 and -Os on x86-64
clang and arm32 gcc. For x86-64 MSVC, it's branch free with -O1 but has a
conditional branch with -O2. I've seen this exact effect with MSVC many times
before, and can only hope that it knows what it's doing...)

[kwiberg-webrtc, 2017-03-13 09:56:21]

The CQ bit was checked by kwiberg@webrtc.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-13 09:56:23]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[hlundin-webrtc, 2017-03-13 10:34:03]

lgtm

[commit-bot: I haz the power, 2017-03-13 11:10:47]

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

[commit-bot: I haz the power, 2017-03-13 11:10:48]

Dry run: This issue passed the CQ dry run.

[kwiberg-webrtc, 2017-03-13 12:26:26]

The CQ bit was checked by kwiberg@webrtc.org

[commit-bot: I haz the power, 2017-03-13 12:26:32]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-03-13 12:28:47]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1489407986555240,
"parent_rev": "53dc23c28f6a4cc89065e41b6db51a5d81cd7954", "commit_rev":
"a1896a649c9238af281a0e73dacbf981d0bc8e64"}

[commit-bot: I haz the power, 2017-03-13 12:28:49]

Description was changed from

==========
iSAC fix entropy coder: Recently added DCHECK could in fact trigger

A DCHECK added in a recent bugfix, which asserted that a signed 64->32
bit cast did not overflow, has been found to not always pass. We fix
this by saturating.

BUG=chromium:693868
==========

to

==========
iSAC fix entropy coder: Recently added DCHECK could in fact trigger

A DCHECK added in a recent bugfix, which asserted that a signed 64->32
bit cast did not overflow, has been found to not always pass. We fix
this by saturating.

BUG=chromium:693868

Review-Url: https://codereview.webrtc.org/2746903002
Cr-Commit-Position: refs/heads/master@{#17209}
Committed:
https://chromium.googlesource.com/external/webrtc/+/a1896a649c9238af281a0e73d...
==========

[commit-bot: I haz the power, 2017-03-13 12:28:50]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/external/webrtc/+/a1896a649c9238af281a0e73d...