89bcbf40b8
math/bits: add examples for right rotation
...
Right rotation is achieved using negative k in RotateLeft*(x, k). Add
examples demonstrating that functionality.
Change-Id: I15dab159accd2937cb18d3fa8ca32da8501567d3
Reviewed-on: https://go-review.googlesource.com/75371
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2017-11-03 20:12:07 +00:00
2ddd07138d
math/bits: complete examples
...
Change-Id: Icbe6885ffd3aa4e77441ab03a2b9a04a9276d5eb
Reviewed-on: https://go-review.googlesource.com/68311
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
2017-10-06 16:58:03 +00:00
92cfd07a6c
math/bits: examples generator
...
Change-Id: Icdd0566d3b7dbc034256e16f8a6b6f1af07069b3
Reviewed-on: https://go-review.googlesource.com/54350
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-08-11 11:05:01 +00:00
762a0bae06
math/bits: Add examples for Reverse functions
...
Change-Id: I30563d31f6acea594cc853cc6b672ec664f90d48
Reviewed-on: https://go-review.googlesource.com/53636
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-08-09 18:02:36 +00:00
fa155066c4
math/bits: some regular examples for functions
...
Change-Id: Iee1b3e116b4dcc4071d6512abc5241eabedaeb5c
Reviewed-on: https://go-review.googlesource.com/53850
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-08-09 13:25:29 +00:00
3e3da54633
math/bits: fix example for OnesCount64
...
Erroneously called OnesCount instead of OnesCount64
Change-Id: Ie877e43f213253e45d31f64931c4a15915849586
Reviewed-on: https://go-review.googlesource.com/53410
Reviewed-by: Chris Broadfoot <cbro@golang.org>
2017-08-05 00:20:37 +00:00
9b1e7cf2ac
math/bits: add examples for OnesCount functions
...
Change-Id: Ie673f9665825a40281c2584d478ba1260f725856
Reviewed-on: https://go-review.googlesource.com/53357
Run-TryBot: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
2017-08-04 23:24:07 +00:00
5f7b3fabe1
math/bits: add examples for leading zero methods
...
Change-Id: Ib491d144387a7675af370f7b925fe6e62440d153
Reviewed-on: https://go-review.googlesource.com/48966
Run-TryBot: Kevin Burke <kev@inburke.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Kevin Burke <kev@inburke.com>
2017-07-15 21:55:58 +00:00
8304d10763
cmd/compile: ppc64x intrinsics for math/bits
...
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 <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
Reviewed-by: Keith Randall <khr@golang.org>
2017-05-10 12:10:56 +00:00
9d01def597
math/bits: support negative rotation count and remove RotateRight
...
For details see the discussion on the issue below.
RotateLeft functions can now be inlined because the don't panic
anymore for negative rotation counts.
name old time/op new time/op delta
RotateLeft-8 6.72ns ± 2% 1.86ns ± 0% -72.33% (p=0.016 n=5+4)
RotateLeft8-8 4.41ns ± 2% 1.67ns ± 1% -62.15% (p=0.008 n=5+5)
RotateLeft16-8 4.46ns ± 6% 1.65ns ± 0% -63.06% (p=0.008 n=5+5)
RotateLeft32-8 4.50ns ± 5% 1.67ns ± 1% -62.86% (p=0.008 n=5+5)
RotateLeft64-8 4.54ns ± 1% 1.85ns ± 1% -59.32% (p=0.008 n=5+5)
https://perf.golang.org/search?q=upload:20170411.4
(Measured on 2.3 GHz Intel Core i7 running macOS 10.12.3.)
For #18616 .
Change-Id: I0828d80d54ec24f8d44954a57b3d6aeedb69c686
Reviewed-on: https://go-review.googlesource.com/40394
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-04-11 23:57:24 +00:00
32b41c8dc7
math/bits: move left-over functionality from bits_impl.go to bits.go
...
Removes an extra function call for TrailingZeroes and thus may
increase chances for inlining.
Change-Id: Iefd8d4402dc89b64baf4e5c865eb3dadade623af
Reviewed-on: https://go-review.googlesource.com/37613
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-28 23:50:47 +00:00
83bc4a2fee
math/bits: faster LeadingZeros and Len functions
...
benchmark old ns/op new ns/op delta
BenchmarkLeadingZeros-8 8.43 3.10 -63.23%
BenchmarkLeadingZeros8-8 8.13 1.33 -83.64%
BenchmarkLeadingZeros16-8 7.34 2.07 -71.80%
BenchmarkLeadingZeros32-8 7.99 2.87 -64.08%
BenchmarkLeadingZeros64-8 8.13 2.96 -63.59%
Measured on 2.3 GHz Intel Core i7 running macOS 10.12.3.
Change-Id: Id343531b408d42ac45f10c76f60e85bdb977f91e
Reviewed-on: https://go-review.googlesource.com/37582
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-28 20:55:13 +00:00
9515cb511a
math/bits: faster TrailingZeroes8
...
For sizes > 8, the existing code is faster.
benchmark old ns/op new ns/op delta
BenchmarkTrailingZeros8-8 1.95 1.29 -33.85%
Measured on 2.3 GHz Intel Core i7 running macOS 10.12.3.
Change-Id: I6f3a33ec633a2c544ec29693c141f2f99335c745
Reviewed-on: https://go-review.googlesource.com/37581
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-28 20:55:01 +00:00
d7a659b11b
math/bits: faster OnesCount using table lookups for sizes 8,16,32
...
For uint64, the existing algorithm is faster.
benchmark old ns/op new ns/op delta
BenchmarkOnesCount8-8 1.95 0.97 -50.26%
BenchmarkOnesCount16-8 2.54 1.39 -45.28%
BenchmarkOnesCount32-8 2.61 1.96 -24.90%
Measured on 2.3 GHz Intel Core i7 running macOS 10.12.3.
Change-Id: I6cc42882fef3d24694720464039161e339a9ae99
Reviewed-on: https://go-review.googlesource.com/37580
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-28 20:54:49 +00:00
e18adbf88d
math/bits: faster Reverse8/16 functions using table lookups
...
Measured on 2.3 GHz Intel Core i7, running macOS 10.12.3:
benchmark old ns/op new ns/op delta
BenchmarkReverse8-8 1.70 0.99 -41.76%
BenchmarkReverse16-8 2.24 1.32 -41.07%
Fixes #19279 .
Change-Id: I398cf8a3513b7fa63c130efc7846a7c5353999d4
Reviewed-on: https://go-review.googlesource.com/37459
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-25 22:18:58 +00:00
ac91a514ff
math/bits: fix incorrect doc strings for TrailingZeros functions
...
Change-Id: I3e40018ab1903d3b9ada7ad7812ba71ea2a428e7
Reviewed-on: https://go-review.googlesource.com/37456
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-25 00:58:25 +00:00
177dfba112
math/bits: faster OnesCount
...
Using some additional suggestions per "Hacker's Delight".
Added documentation and extra tests.
Measured on 1.7 GHz Intel Core i7, running macOS 10.12.3.
benchmark old ns/op new ns/op delta
BenchmarkOnesCount-4 7.34 5.38 -26.70%
BenchmarkOnesCount8-4 2.03 1.98 -2.46%
BenchmarkOnesCount16-4 2.56 2.50 -2.34%
BenchmarkOnesCount32-4 2.98 2.39 -19.80%
BenchmarkOnesCount64-4 4.22 2.96 -29.86%
Change-Id: I566b0ef766e55cf5776b1662b6016024ebe5d878
Reviewed-on: https://go-review.googlesource.com/37223
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-19 18:50:48 +00:00
a4a3d63dbe
math/bits: added benchmarks for Leading/TrailingZeros
...
BenchmarkLeadingZeros-8 200000000 8.80 ns/op
BenchmarkLeadingZeros8-8 200000000 8.21 ns/op
BenchmarkLeadingZeros16-8 200000000 7.49 ns/op
BenchmarkLeadingZeros32-8 200000000 7.80 ns/op
BenchmarkLeadingZeros64-8 200000000 8.67 ns/op
BenchmarkTrailingZeros-8 1000000000 2.05 ns/op
BenchmarkTrailingZeros8-8 2000000000 1.94 ns/op
BenchmarkTrailingZeros16-8 2000000000 1.94 ns/op
BenchmarkTrailingZeros32-8 2000000000 1.92 ns/op
BenchmarkTrailingZeros64-8 2000000000 2.03 ns/op
Change-Id: I45497bf2d6369ba6cfc88ded05aa735908af8908
Reviewed-on: https://go-review.googlesource.com/37220
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 23:41:16 +00:00
19028bdd18
math/bits: faster Rotate functions, added respective benchmarks
...
Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.
benchmark old ns/op new ns/op delta
BenchmarkRotateLeft-8 7.87 7.00 -11.05%
BenchmarkRotateLeft8-8 8.41 4.52 -46.25%
BenchmarkRotateLeft16-8 8.07 4.55 -43.62%
BenchmarkRotateLeft32-8 8.36 4.73 -43.42%
BenchmarkRotateLeft64-8 7.93 4.78 -39.72%
BenchmarkRotateRight-8 8.23 6.72 -18.35%
BenchmarkRotateRight8-8 8.76 4.39 -49.89%
BenchmarkRotateRight16-8 9.07 4.44 -51.05%
BenchmarkRotateRight32-8 8.85 4.46 -49.60%
BenchmarkRotateRight64-8 8.11 4.43 -45.38%
Change-Id: I79ea1e9e6fc65f95794a91f860a911efed3aa8a1
Reviewed-on: https://go-review.googlesource.com/37219
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 23:40:45 +00:00
a12edb8db6
math/bits: faster OnesCount, added respective benchmarks
...
Also: Changed Reverse/ReverseBytes implementations to use
the same (smaller) masks as OnesCount.
BenchmarkOnesCount-8 37.0 6.26 -83.08%
BenchmarkOnesCount8-8 7.24 1.99 -72.51%
BenchmarkOnesCount16-8 11.3 2.47 -78.14%
BenchmarkOnesCount32-8 18.4 3.02 -83.59%
BenchmarkOnesCount64-8 40.0 3.78 -90.55%
BenchmarkReverse-8 6.69 6.22 -7.03%
BenchmarkReverse8-8 1.64 1.64 +0.00%
BenchmarkReverse16-8 2.26 2.18 -3.54%
BenchmarkReverse32-8 2.88 2.87 -0.35%
BenchmarkReverse64-8 5.64 4.34 -23.05%
BenchmarkReverseBytes-8 2.48 2.17 -12.50%
BenchmarkReverseBytes16-8 0.63 0.95 +50.79%
BenchmarkReverseBytes32-8 1.13 1.24 +9.73%
BenchmarkReverseBytes64-8 2.50 2.16 -13.60%
OnesCount-8 37.0ns ± 0% 6.3ns ± 0% ~ (p=1.000 n=1+1)
OnesCount8-8 7.24ns ± 0% 1.99ns ± 0% ~ (p=1.000 n=1+1)
OnesCount16-8 11.3ns ± 0% 2.5ns ± 0% ~ (p=1.000 n=1+1)
OnesCount32-8 18.4ns ± 0% 3.0ns ± 0% ~ (p=1.000 n=1+1)
OnesCount64-8 40.0ns ± 0% 3.8ns ± 0% ~ (p=1.000 n=1+1)
Reverse-8 6.69ns ± 0% 6.22ns ± 0% ~ (p=1.000 n=1+1)
Reverse8-8 1.64ns ± 0% 1.64ns ± 0% ~ (all samples are equal)
Reverse16-8 2.26ns ± 0% 2.18ns ± 0% ~ (p=1.000 n=1+1)
Reverse32-8 2.88ns ± 0% 2.87ns ± 0% ~ (p=1.000 n=1+1)
Reverse64-8 5.64ns ± 0% 4.34ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes-8 2.48ns ± 0% 2.17ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes16-8 0.63ns ± 0% 0.95ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes32-8 1.13ns ± 0% 1.24ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes64-8 2.50ns ± 0% 2.16ns ± 0% ~ (p=1.000 n=1+1)
Change-Id: I591b0ffc83fc3a42828256b6e5030f32c64f9497
Reviewed-on: https://go-review.googlesource.com/37218
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 23:40:10 +00:00
4498b68390
math/bits: faster Reverse, ReverseBytes
...
- moved from: x&m>>k | x&^m<<k to: x&m>>k | x<<k&m
This permits use of the same constant m twice (*) which may be
better for machines that can't use large immediate constants
directly with an AND instruction and have to load them explicitly.
*) CPUs don't usually have a &^ instruction, so x&^m becomes x&(^m)
- simplified returns
This improves the generated code because the compiler recognizes
x>>k | x<<k as ROT when k is the bitsize of x.
The 8-bit versions of these instructions can be significantly faster
still if they are replaced with table lookups, as long as the table
is in cache. If the table is not in cache, table-lookup is probably
slower, hence the choice of an explicit register-only implementation
for now.
BenchmarkReverse-8 8.50 6.86 -19.29%
BenchmarkReverse8-8 2.17 1.74 -19.82%
BenchmarkReverse16-8 2.89 2.34 -19.03%
BenchmarkReverse32-8 3.55 2.95 -16.90%
BenchmarkReverse64-8 6.81 5.57 -18.21%
BenchmarkReverseBytes-8 3.49 2.48 -28.94%
BenchmarkReverseBytes16-8 0.93 0.62 -33.33%
BenchmarkReverseBytes32-8 1.55 1.13 -27.10%
BenchmarkReverseBytes64-8 2.47 2.47 +0.00%
Reverse-8 8.50ns ± 0% 6.86ns ± 0% ~ (p=1.000 n=1+1)
Reverse8-8 2.17ns ± 0% 1.74ns ± 0% ~ (p=1.000 n=1+1)
Reverse16-8 2.89ns ± 0% 2.34ns ± 0% ~ (p=1.000 n=1+1)
Reverse32-8 3.55ns ± 0% 2.95ns ± 0% ~ (p=1.000 n=1+1)
Reverse64-8 6.81ns ± 0% 5.57ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes-8 3.49ns ± 0% 2.48ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes16-8 0.93ns ± 0% 0.62ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes32-8 1.55ns ± 0% 1.13ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes64-8 2.47ns ± 0% 2.47ns ± 0% ~ (all samples are equal)
Change-Id: I0064de8c7e0e568ca7885d6f7064344bef91a06d
Reviewed-on: https://go-review.googlesource.com/37215
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-17 22:20:28 +00:00
3a239a6ae4
math/bits: fix benchmarks (make sure calls don't get optimized away)
...
Sum up function results and store them in an exported (global)
variable. This prevents the compiler from optimizing away the
otherwise side-effect free function calls.
We now have more realistic set of benchmark numbers...
Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.
Note: These measurements are based on the same "old"
implementation as the prior measurements (commit 7d5c003https://go-review.googlesource.com/37213
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 20:58:12 +00:00
ddb15cea4a
math/bits: much faster ReverseBytes, added respective benchmarks
...
Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.
benchmark old ns/op new ns/op delta
BenchmarkReverseBytes-8 11.4 3.51 -69.21%
BenchmarkReverseBytes16-8 6.87 0.64 -90.68%
BenchmarkReverseBytes32-8 7.79 0.65 -91.66%
BenchmarkReverseBytes64-8 11.6 0.64 -94.48%
name old time/op new time/op delta
ReverseBytes-8 11.4ns ± 0% 3.5ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes16-8 6.87ns ± 0% 0.64ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes32-8 7.79ns ± 0% 0.65ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes64-8 11.6ns ± 0% 0.6ns ± 0% ~ (p=1.000 n=1+1)
Change-Id: I67b529652b3b613c61687e9e185e8d4ee40c51a2
Reviewed-on: https://go-review.googlesource.com/37211
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 19:38:26 +00:00
7d5c003a3a
math/bits: much faster Reverse, added respective benchmarks
...
Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.
name old time/op new time/op delta
Reverse-8 76.6ns ± 0% 8.1ns ± 0% ~ (p=1.000 n=1+1)
Reverse8-8 12.6ns ± 0% 0.6ns ± 0% ~ (p=1.000 n=1+1)
Reverse16-8 20.8ns ± 0% 0.6ns ± 0% ~ (p=1.000 n=1+1)
Reverse32-8 36.5ns ± 0% 0.6ns ± 0% ~ (p=1.000 n=1+1)
Reverse64-8 74.0ns ± 0% 6.4ns ± 0% ~ (p=1.000 n=1+1)
benchmark old ns/op new ns/op delta
BenchmarkReverse-8 76.6 8.07 -89.46%
BenchmarkReverse8-8 12.6 0.64 -94.92%
BenchmarkReverse16-8 20.8 0.64 -96.92%
BenchmarkReverse32-8 36.5 0.64 -98.25%
BenchmarkReverse64-8 74.0 6.38 -91.38%
Change-Id: I6b99b10cee2f2babfe79342b50ee36a45a34da30
Reviewed-on: https://go-review.googlesource.com/37149
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 19:38:13 +00:00
81acd308a4
math/bits: expand doc strings for all functions
...
Follow-up on https://go-review.googlesource.com/36315 .
No functionality change.
For #18616 .
Change-Id: Id4df34dd7d0381be06eea483a11bf92f4a01f604
Reviewed-on: https://go-review.googlesource.com/37140
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 19:02:56 +00:00
661e2179e5
math/bits: added package for bit-level counting and manipulation
...
Initial platform-independent implementation.
For #18616 .
Change-Id: I4585c55b963101af9059c06c1b8a866cb384754c
Reviewed-on: https://go-review.googlesource.com/36315
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2017-02-16 21:54:59 +00:00
Tobias Klauser
griesemer
romanyx
Wembley G. Leach, Jr
Francesc Campoy Flores
Francesc Campoy
Dylan Waits
Lynn Boger