delta/go-git.git/src/strings/strings_generic.go, branch dev.inline

bytes, strings: optimize multi-byte index operations on s390x

2016-11-01T13:17:57+00:00

Use vector instructions to speed up indexing operations for short
strings (64 bytes or less).

bytes_s390x.go and strings_s390x.go are based on their amd64
equivalents in CL 31690.

bytes package:

name                   old time/op    new time/op    delta
Index/10                 40.3ns ± 7%    11.3ns ± 4%    -72.06%  (p=0.000 n=10+10)
Index/32                  196ns ± 1%      27ns ± 2%    -86.25%  (p=0.000 n=10+10)
Index/4K                 28.9µs ± 1%     1.5µs ± 2%    -94.94%    (p=0.000 n=9+9)
Index/4M                 30.1ms ± 2%     1.5ms ± 3%    -94.94%  (p=0.000 n=10+10)
Index/64M                 549ms ±13%      28ms ± 3%    -94.87%   (p=0.000 n=10+9)
IndexEasy/10             18.8ns ±11%    11.5ns ± 2%    -38.81%  (p=0.000 n=10+10)
IndexEasy/32             23.6ns ± 6%    28.1ns ± 3%    +19.29%  (p=0.000 n=10+10)
IndexEasy/4K              251ns ± 5%     223ns ± 8%    -11.04%  (p=0.000 n=10+10)
IndexEasy/4M              318µs ± 9%     266µs ± 8%    -16.42%  (p=0.000 n=10+10)
IndexEasy/64M            14.7ms ±16%    13.2ms ±11%    -10.22%  (p=0.001 n=10+10)

strings package:

name                   old time/op  new time/op  delta
IndexRune              88.1ns ±16%  28.9ns ± 4%  -67.20%  (p=0.000 n=10+10)
IndexRuneLongString     456ns ± 7%    34ns ± 3%  -92.50%  (p=0.000 n=10+10)
IndexRuneFastPath      12.9ns ±14%  11.1ns ± 6%  -13.84%  (p=0.000 n=10+10)
Index                  13.0ns ± 7%  11.3ns ± 4%  -13.31%  (p=0.000 n=10+10)
IndexHard1             3.38ms ± 9%  0.07ms ± 1%  -97.79%  (p=0.000 n=10+10)
IndexHard2             3.58ms ± 7%  0.37ms ± 2%  -89.78%  (p=0.000 n=10+10)
IndexHard3             3.47ms ± 7%  0.75ms ± 1%  -78.52%  (p=0.000 n=10+10)
IndexHard4             3.56ms ± 6%  1.34ms ± 0%  -62.39%    (p=0.000 n=9+9)

Change-Id: If36c2afb8c02e80fcaa1cf5ec2abb0a2be08c7d1
Reviewed-on: https://go-review.googlesource.com/32447
Run-TryBot: Michael Munday 
Reviewed-by: Brad Fitzpatrick

all: make copyright headers consistent with one space after period

2016-03-01T23:34:33+00:00

This is a subset of https://golang.org/cl/20022 with only the copyright
header lines, so the next CL will be smaller and more reviewable.

Go policy has been single space after periods in comments for some time.

The copyright header template at:

    https://golang.org/doc/contribute.html#copyright

also uses a single space.

Make them all consistent.

Change-Id: Icc26c6b8495c3820da6b171ca96a74701b4a01b0
Reviewed-on: https://go-review.googlesource.com/20111
Run-TryBot: Brad Fitzpatrick 
Reviewed-by: Ian Lance Taylor 
Reviewed-by: Matthew Dempsky 
TryBot-Result: Gobot Gobot

strings: add asm version of Index() for short strings on amd64

2015-11-03T16:04:28+00:00

Currently we have special case for 1-byte strings,
This extends this to strings shorter than 32 bytes on amd64.
Results (broadwell):

name                 old time/op  new time/op  delta
IndexRune-4          57.4ns ± 0%  57.5ns ± 0%   +0.10%        (p=0.000 n=20+19)
IndexRuneFastPath-4  20.4ns ± 0%  20.4ns ± 0%     ~     (all samples are equal)
Index-4              21.0ns ± 0%  21.8ns ± 0%   +3.81%        (p=0.000 n=20+20)
LastIndex-4          7.07ns ± 1%  6.98ns ± 0%   -1.21%        (p=0.000 n=20+16)
IndexByte-4          18.3ns ± 0%  18.3ns ± 0%     ~     (all samples are equal)
IndexHard1-4         1.46ms ± 0%  0.39ms ± 0%  -73.06%        (p=0.000 n=16+16)
IndexHard2-4         1.46ms ± 0%  0.30ms ± 0%  -79.55%        (p=0.000 n=18+18)
IndexHard3-4         1.46ms ± 0%  0.66ms ± 0%  -54.68%        (p=0.000 n=19+19)
LastIndexHard1-4     1.46ms ± 0%  1.46ms ± 0%   -0.01%        (p=0.036 n=18+20)
LastIndexHard2-4     1.46ms ± 0%  1.46ms ± 0%     ~           (p=0.588 n=19+19)
LastIndexHard3-4     1.46ms ± 0%  1.46ms ± 0%     ~           (p=0.283 n=17+20)
IndexTorture-4       11.1µs ± 0%  11.1µs ± 0%   +0.01%        (p=0.000 n=18+17)

Change-Id: I892781549f558f698be4e41f9f568e3d0611efb5
Reviewed-on: https://go-review.googlesource.com/16430
Reviewed-by: Keith Randall 
Run-TryBot: Ilya Tocar