delta/go-git.git/src/math, branch dev.debug

math/bits: add examples for leading zero methods

2017-07-15T21:55:58+00:00

Change-Id: Ib491d144387a7675af370f7b925fe6e62440d153
Reviewed-on: https://go-review.googlesource.com/48966
Run-TryBot: Kevin Burke 
TryBot-Result: Gobot Gobot 
Reviewed-by: Kevin Burke

math/rand: add concurrency warning to overview comment

2017-07-15T20:34:17+00:00

Change-Id: I52efa7aa72a23256e5ca56470ffeba975ed8f739
Reviewed-on: https://go-review.googlesource.com/48760
Reviewed-by: Bryan Mills

math: add a Sqrt example

2017-07-15T20:12:22+00:00

Change-Id: I259e25b9d0b069912053a250e9739e04fafca54d
Reviewed-on: https://go-review.googlesource.com/48892
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

math: clarify comment about bit-identical results across architectures

2017-06-06T22:32:34+00:00

Updates #18354.

Change-Id: I76bc4a73d8dc99eeda14b395e451d75a65184191
Reviewed-on: https://go-review.googlesource.com/45013
Reviewed-by: Brad Fitzpatrick 
Reviewed-by: Rob Pike

math: add doc note about floating point operation

2017-06-06T20:20:41+00:00

Go doesn't guarantee that the result of floating point operations will
be the same on different architectures. It was not stated in the
documentation, that can lead to confusion.

Fixes #18354

Change-Id: Idb1b4c256fb9a7158a74256136eca3b8ce44476f
Reviewed-on: https://go-review.googlesource.com/34938
Reviewed-by: Ian Lance Taylor

math/big: fix Add, Sub when receiver aliases 2nd operand

2017-05-31T10:28:05+00:00

Fixes #20490

Change-Id: I9cfa604f9ff94df779cb9b4cbbd706258fc473ac
Reviewed-on: https://go-review.googlesource.com/44150
Run-TryBot: Alberto Donizetti 
TryBot-Result: Gobot Gobot 
Reviewed-by: Keith Randall

internal/cpu: new package to detect cpu features

2017-05-10T17:02:21+00:00

Implements detection of x86 cpu features that
are used in the go standard library.

Changes all standard library packages to use the new cpu package
instead of using runtime internal variables to check x86 cpu features.

Updates: #15403

Change-Id: I2999a10cb4d9ec4863ffbed72f4e021a1dbc4bb9
Reviewed-on: https://go-review.googlesource.com/41476
Reviewed-by: Brad Fitzpatrick 
Reviewed-by: Keith Randall 
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot

cmd/compile: ppc64x intrinsics for math/bits

2017-05-10T12:10:56+00:00

This adds math/bits intrinsics for OnesCount, Len, TrailingZeros on
ppc64x.

benchmark                       old ns/op     new ns/op     delta
BenchmarkLeadingZeros-16        4.26          1.71          -59.86%
BenchmarkLeadingZeros16-16      3.04          1.83          -39.80%
BenchmarkLeadingZeros32-16      3.31          1.82          -45.02%
BenchmarkLeadingZeros64-16      3.69          1.71          -53.66%
BenchmarkTrailingZeros-16       2.55          1.62          -36.47%
BenchmarkTrailingZeros32-16     2.55          1.77          -30.59%
BenchmarkTrailingZeros64-16     2.78          1.62          -41.73%
BenchmarkOnesCount-16           3.19          0.93          -70.85%
BenchmarkOnesCount32-16         2.55          1.18          -53.73%
BenchmarkOnesCount64-16         3.22          0.93          -71.12%

Update #18616

I also made a change to bits_test.go because when debugging some failures
the output was not quite providing the right argument information.

Change-Id: Ia58d31d1777cf4582a4505f85b11a1202ca07d3e
Reviewed-on: https://go-review.googlesource.com/41630
Run-TryBot: Lynn Boger 
TryBot-Result: Gobot Gobot 
Reviewed-by: Carlos Eduardo Seo 
Reviewed-by: Keith Randall

math: use SIMD to accelerate additional scalar math functions on s390x

2017-05-08T19:52:30+00:00

As necessary, math functions were structured to use stubs, so that they can
be accelerated with assembly on any platform.

Technique used was minimax polynomial approximation using tables of
polynomial coefficients, with argument range reduction.

Benchmark         New     Old     Speedup
BenchmarkAcos     12.2    47.5    3.89
BenchmarkAcosh    18.5    56.2    3.04
BenchmarkAsin     13.1    40.6    3.10
BenchmarkAsinh    19.4    62.8    3.24
BenchmarkAtan     10.1    23      2.28
BenchmarkAtanh    19.1    53.2    2.79
BenchmarkAtan2    16.5    33.9    2.05
BenchmarkCbrt     14.8    58      3.92
BenchmarkErf      10.8    20.1    1.86
BenchmarkErfc     11.2    23.5    2.10
BenchmarkExp      8.77    53.8    6.13
BenchmarkExpm1    10.1    38.3    3.79
BenchmarkLog      13.1    40.1    3.06
BenchmarkLog1p    12.7    38.3    3.02
BenchmarkPowInt   31.7    40.5    1.28
BenchmarkPowFrac  33.1    141     4.26
BenchmarkTan      11.5    30      2.61

Accuracy was tested against a high precision
reference function to determine maximum error.
Note: ulperr is error in "units in the last place"

       max
      ulperr
Acos  1.15
Acosh 1.07
Asin  2.22
Asinh 1.72
Atan  1.41
Atanh 3.00
Atan2 1.45
Cbrt  1.18
Erf   1.29
Erfc  4.82
Exp   1.00
Expm1 2.26
Log   0.94
Log1p 2.39
Tan   3.14

Pow will have 99.99% correctly rounded results with reasonable inputs
producing numeric (non Inf or NaN) results

Change-Id: I850e8cf7b70426e8b54ec49d74acd4cddc8c6cb2
Reviewed-on: https://go-review.googlesource.com/38585
Reviewed-by: Michael Munday 
Run-TryBot: Michael Munday 
TryBot-Result: Gobot Gobot

math/big: improve performance for addVV/subVV for ppc64x

2017-04-25T13:15:39+00:00

This change adds a better asm implementation of addVV for ppc64x, with speedups
up to nearly 3x in the best cases.

benchmark                   old ns/op     new ns/op     delta
BenchmarkAddVV/1-8          7.33          5.81          -20.74%
BenchmarkAddVV/2-8          8.72          6.49          -25.57%
BenchmarkAddVV/3-8          10.5          7.08          -32.57%
BenchmarkAddVV/4-8          12.7          7.57          -40.39%
BenchmarkAddVV/5-8          14.3          8.06          -43.64%
BenchmarkAddVV/10-8         27.6          11.1          -59.78%
BenchmarkAddVV/100-8        218           82.4          -62.20%
BenchmarkAddVV/1000-8       2064          718           -65.21%
BenchmarkAddVV/10000-8      20536         7153          -65.17%
BenchmarkAddVV/100000-8     211004        72403         -65.69%

benchmark                   old MB/s     new MB/s     speedup
BenchmarkAddVV/1-8          8729.74      11006.26     1.26x
BenchmarkAddVV/2-8          14683.65     19707.55     1.34x
BenchmarkAddVV/3-8          18226.96     27103.63     1.49x
BenchmarkAddVV/4-8          20204.50     33805.81     1.67x
BenchmarkAddVV/5-8          22348.64     39694.06     1.78x
BenchmarkAddVV/10-8         23212.74     57631.08     2.48x
BenchmarkAddVV/100-8        29300.07     77629.53     2.65x
BenchmarkAddVV/1000-8       31000.56     89094.54     2.87x
BenchmarkAddVV/10000-8      31163.61     89469.16     2.87x
BenchmarkAddVV/100000-8     30331.16     88393.73     2.91x

It also adds the use of CTR for the loop counter in subVV, instead of
manually updating the loop counter. This is slightly faster.

Change-Id: Ic4b05cad384fd057972d46a5618ed5c3039d7460
Reviewed-on: https://go-review.googlesource.com/41010
Run-TryBot: Lynn Boger 
TryBot-Result: Gobot Gobot 
Reviewed-by: Lynn Boger