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Rémy Oudompheng 61a08fc6ce strconv: Implement Ryū algorithm for ftoa shortest mode
This patch implements the algorithm from Ulf Adams,
"Ryū: Fast Float-to-String Conversion" (doi:10.1145/3192366.3192369)
for formatting floating-point numbers with a fixed number of decimal
digits.

It is not a direct translation of the reference C implementation
but still follows the original paper. In particular, it uses full
128-bit powers of 10, which allows for more precision in the other
modes (fixed ftoa, atof).

name                              old time/op  new time/op   delta
AppendFloat/Decimal-4             49.6ns ± 3%   59.3ns ± 0%  +19.59%  (p=0.008 n=5+5)
AppendFloat/Float-4                122ns ± 1%     91ns ± 1%  -25.92%  (p=0.008 n=5+5)
AppendFloat/Exp-4                 89.3ns ± 1%  100.0ns ± 1%  +11.98%  (p=0.008 n=5+5)
AppendFloat/NegExp-4              88.3ns ± 2%   97.1ns ± 1%   +9.87%  (p=0.008 n=5+5)
AppendFloat/LongExp-4              143ns ± 2%    103ns ± 0%  -28.17%  (p=0.016 n=5+4)
AppendFloat/Big-4                  144ns ± 1%    110ns ± 1%  -23.26%  (p=0.008 n=5+5)
AppendFloat/BinaryExp-4           46.2ns ± 2%   46.0ns ± 1%     ~     (p=0.603 n=5+5)
AppendFloat/32Integer-4           49.1ns ± 1%   58.7ns ± 1%  +19.57%  (p=0.008 n=5+5)
AppendFloat/32ExactFraction-4     95.6ns ± 1%   88.6ns ± 1%   -7.30%  (p=0.008 n=5+5)
AppendFloat/32Point-4              122ns ± 1%     87ns ± 1%  -28.63%  (p=0.008 n=5+5)
AppendFloat/32Exp-4               88.6ns ± 2%   95.0ns ± 1%   +7.29%  (p=0.008 n=5+5)
AppendFloat/32NegExp-4            87.2ns ± 1%   91.3ns ± 1%   +4.63%  (p=0.008 n=5+5)
AppendFloat/32Shortest-4           107ns ± 1%     82ns ± 0%  -24.08%  (p=0.008 n=5+5)
AppendFloat/Slowpath64-4          1.00µs ± 1%   0.10µs ± 0%  -89.92%  (p=0.016 n=5+4)
AppendFloat/SlowpathDenormal64-4  34.1µs ± 3%    0.1µs ± 1%  -99.72%  (p=0.008 n=5+5)

Fixes #15672

Change-Id: Ib90dfa245f62490a6666671896013cf3f9a1fb22
Reviewed-on: https://go-review.googlesource.com/c/go/+/170080
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Trust: Nigel Tao <nigeltao@golang.org>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
2021-04-15 09:18:03 +00:00
.github .github: add link to questions in ISSUE_TEMPLATE 2020-01-06 17:05:31 +00:00
api syscall: restore broken GetQueuedCompletionStatus signature but make it not crash 2021-02-24 23:35:00 +00:00
doc runtime/cgo: add Handle for managing (c)go pointers 2021-04-06 23:39:42 +00:00
lib/time lib/time, time/tzdata: update tzdata to 2021a 2021-01-25 16:08:46 +00:00
misc runtime, cgo/test: improve debugging output 2021-04-13 23:56:27 +00:00
src strconv: Implement Ryū algorithm for ftoa shortest mode 2021-04-15 09:18:03 +00:00
test cmd/compile: propagate pragmas from generic function to stenciled implementation 2021-04-15 00:29:05 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
.gitignore .gitignore: ignore src/cmd/dist/dist 2017-10-28 21:55:49 +00:00
AUTHORS A+C: add new e-mail addresses for Andy Pan 2021-03-12 02:56:04 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS A+C: add new e-mail addresses for Andy Pan 2021-03-12 02:56:04 +00:00
LICENSE doc: revert copyright date to 2009 2016-06-01 22:40:04 +00:00
PATENTS LICENSE: separate, change PATENTS text 2010-12-06 16:31:59 -05:00
README.md README: pull gopher image from website 2021-02-16 18:25:10 +00:00
SECURITY.md SECURITY.md: update go versions 2019-09-26 15:34:57 +00:00

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