WebRtcSpl_SynthesisQMF: Fix UBSan fuzzer bug (left shift of negative value)

WebRtcSpl_SynthesisQMF: Fix UBSan fuzzer bug (left shift of negative value)

BUG=chromium:614033
Committed: https://crrev.com/96bbdd585eb2ddd9fa11da01b46ae71d7be1672a
Cr-Commit-Position: refs/heads/master@{#13814}

[kwiberg-webrtc, 2016-08-17 16:18:22]

kwiberg@webrtc.org changed reviewers:
+ ossu@webrtc.org

[kwiberg-webrtc, 2016-08-17 16:19:42]

https://codereview.webrtc.org/2253943002/diff/1/webrtc/common_audio/signal_pr...
File webrtc/common_audio/signal_processing/splitting_filter.c (left):

https://codereview.webrtc.org/2253943002/diff/1/webrtc/common_audio/signal_pr...
webrtc/common_audio/signal_processing/splitting_filter.c:187: half_in2[i] =
WEBRTC_SPL_LSHIFT_W32(tmp, 10);
Macro definition:

#define WEBRTC_SPL_LSHIFT_W32(x, c)     ((x) << (c))

[ossu, 2016-08-17 16:36:51]

This looks about right. I wish there were a way to do it without introducing
multiplication, but I guess that's less of an issue now than it was in the
nineties. :)

LGTM

[kwiberg-webrtc, 2016-08-17 16:41:45]

On 2016/08/17 16:36:51, ossu wrote:
> This looks about right. I wish there were a way to do it without introducing
> multiplication, but I guess that's less of an issue now than it was in the
> nineties. :)

I'll bet that the compiler will implement signed multiplication by the constant
1<<10 with a left shift instruction...

Relevant 90s film quote:

"Do not try and execute the multiplication. That's impossible. Instead... only
try to realize the truth."
"What truth?"
"There is no multiplication."

[kwiberg-webrtc, 2016-08-17 16:42:18]

The CQ bit was checked by kwiberg@webrtc.org

[commit-bot: I haz the power, 2016-08-17 16:42:30]

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, 2016-08-17 18:13:53]

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

[commit-bot: I haz the power, 2016-08-17 18:13:53]

Try jobs failed on following builders:
  android_arm64_rel on master.tryserver.webrtc (JOB_TIMED_OUT, no build URL)

[kwiberg-webrtc, 2016-08-18 09:02:56]

The CQ bit was checked by kwiberg@webrtc.org

[commit-bot: I haz the power, 2016-08-18 09:03:04]

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, 2016-08-18 10:17:09]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-18 10:17:16]

Description was changed from

==========
WebRtcSpl_SynthesisQMF: Fix UBSan fuzzer bug (left shift of negative value)

BUG=chromium:614033
==========

to

==========
WebRtcSpl_SynthesisQMF: Fix UBSan fuzzer bug (left shift of negative value)

BUG=chromium:614033

Committed: https://crrev.com/96bbdd585eb2ddd9fa11da01b46ae71d7be1672a
Cr-Commit-Position: refs/heads/master@{#13814}
==========

[commit-bot: I haz the power, 2016-08-18 10:17:17]

Patchset 1 (id:??) landed as
https://crrev.com/96bbdd585eb2ddd9fa11da01b46ae71d7be1672a
Cr-Commit-Position: refs/heads/master@{#13814}