SkPMFloat::trunc()

SkPMFloat::trunc()

Add and test trunc(), which is what get() used to be before rounding.
Using trunc() is a ~40% speedup on our linear gradient bench.

#neon #floats
BUG=skia:3592
#n5
#n9
CQ_INCLUDE_TRYBOTS=client.skia.android:Test-Android-Nexus5-Adreno330-Arm7-Debug-Trybot;client.skia.android:Test-Android-Nexus9-TegraK1-Arm64-Release-Trybot

Committed: https://skia.googlesource.com/skia/+/3d4c4a5a9feff961c6ba70443fa40ea1ca0a503e

[mtklein_C, 2015-03-26 02:27:24]

mtklein@chromium.org changed reviewers:
+ reed@google.com

[mtklein_C, 2015-03-26 02:27:24]

Nothing new; just the follow up from today.

[mtklein, 2015-03-26 02:29:36]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-03-26 02:30:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1032243002/1

[commit-bot: I haz the power, 2015-03-26 02:30:05]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-03-26 08:30 UTC

[commit-bot: I haz the power, 2015-03-26 08:30:02]

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

[commit-bot: I haz the power, 2015-03-26 08:30:03]

No LGTM from a valid reviewer yet. Please ask for an LGTM from a
full Skia committer from
https://skia.googlesource.com/skia/+/master/CQ_COMMITTERS

[reed1, 2015-03-26 13:05:10]

lgtm w/ comment request

https://codereview.chromium.org/1032243002/diff/1/src/core/SkPMFloat.h
File src/core/SkPMFloat.h (right):

https://codereview.chromium.org/1032243002/diff/1/src/core/SkPMFloat.h#newcode60
src/core/SkPMFloat.h:60: // Like get(), but truncates instead of rounding.
floor or (int) ?
i.e. can you document what happens to negative values?

[mtklein, 2015-03-26 13:26:25]

https://codereview.chromium.org/1032243002/diff/1/src/core/SkPMFloat.h
File src/core/SkPMFloat.h (right):

https://codereview.chromium.org/1032243002/diff/1/src/core/SkPMFloat.h#newcode60
src/core/SkPMFloat.h:60: // Like get(), but truncates instead of rounding.
On 2015/03/26 13:05:10, reed1 wrote:
> floor or (int) ?
> i.e. can you document what happens to negative values?

Done.

// The domain of this function is (-1.0f, 256.0f).  Values in (-1.0f, 0.0f]
trunc to a zero.

[mtklein, 2015-03-26 13:27:05]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-03-26 13:27:06]

The patchset sent to the CQ was uploaded after l-g-t-m from reed@google.com
Link to the patchset: https://codereview.chromium.org/1032243002/#ps40001
(title: "document + test negative domain")

[commit-bot: I haz the power, 2015-03-26 13:27:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1032243002/40001

[mtklein, 2015-03-26 15:06:33]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-03-26 15:06:34]

The patchset sent to the CQ was uploaded after l-g-t-m from reed@google.com
Link to the patchset: https://codereview.chromium.org/1032243002/#ps60001
(title: "remove isValid assert in _none trunc()")

[commit-bot: I haz the power, 2015-03-26 15:06:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1032243002/60001

[commit-bot: I haz the power, 2015-03-26 19:32:35]

Committed patchset #4 (id:60001) as
https://skia.googlesource.com/skia/+/3d4c4a5a9feff961c6ba70443fa40ea1ca0a503e