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Russ Cox 3c40ee0fe0 cmd/gc: simplify compiled code for explicit zeroing
Among other things, *x = T{} does not need a write barrier.
The changes here avoid an unnecessary copy even when
no pointers are involved, so it may have larger effects.

In 6g and 8g, avoid manually repeated STOSQ in favor of
writing explicit MOVs, under the theory that the MOVs
should have fewer dependencies and pipeline better.

Benchmarks compare best of 5 on a 2012 MacBook Pro Core i5
with TurboBoost disabled. Most improvements can be explained
by the changes in this CL.

The effect in Revcomp is real but harder to explain: none of
the instructions in the inner loop changed. I suspect loop
alignment but really have no idea.

benchmark                       old         new         delta
BenchmarkBinaryTree17           3809027371  3819907076  +0.29%
BenchmarkFannkuch11             3607547556  3686983012  +2.20%
BenchmarkFmtFprintfEmpty        118         103         -12.71%
BenchmarkFmtFprintfString       289         277         -4.15%
BenchmarkFmtFprintfInt          304         290         -4.61%
BenchmarkFmtFprintfIntInt       507         458         -9.66%
BenchmarkFmtFprintfPrefixedInt  425         408         -4.00%
BenchmarkFmtFprintfFloat        555         555         +0.00%
BenchmarkFmtManyArgs            1835        1733        -5.56%
BenchmarkGobDecode              14738209    14639331    -0.67%
BenchmarkGobEncode              14239039    13703571    -3.76%
BenchmarkGzip                   538211054   538701315   +0.09%
BenchmarkGunzip                 135430877   134818459   -0.45%
BenchmarkHTTPClientServer       116488      116618      +0.11%
BenchmarkJSONEncode             28923406    29294334    +1.28%
BenchmarkJSONDecode             105779820   104289543   -1.41%
BenchmarkMandelbrot200          5791758     5771964     -0.34%
BenchmarkGoParse                5376642     5310943     -1.22%
BenchmarkRegexpMatchEasy0_32    195         190         -2.56%
BenchmarkRegexpMatchEasy0_1K    477         455         -4.61%
BenchmarkRegexpMatchEasy1_32    170         165         -2.94%
BenchmarkRegexpMatchEasy1_1K    1410        1394        -1.13%
BenchmarkRegexpMatchMedium_32   336         329         -2.08%
BenchmarkRegexpMatchMedium_1K   108979      106328      -2.43%
BenchmarkRegexpMatchHard_32     5854        5821        -0.56%
BenchmarkRegexpMatchHard_1K     185089      182838      -1.22%
BenchmarkRevcomp                834920364   780202624   -6.55%
BenchmarkTemplate               137046937   129728756   -5.34%
BenchmarkTimeParse              600         594         -1.00%
BenchmarkTimeFormat             559         539         -3.58%

LGTM=r
R=r
CC=golang-codereviews, iant, khr, rlh
https://golang.org/cl/157910047
2014-10-15 19:33:15 -04:00
api unicode: strconv: regexp: Upgrade to Unicode 7.0.0. 2014-08-18 20:26:10 +02:00
doc go1.4: add note about change to bufio.SplitFunc at EOF 2014-10-12 11:41:55 -07:00
include liblink: require DATA lines to be ordered by offset, with no overlap 2014-10-14 23:25:12 -04:00
lib codereview: do not hit upload_complete on first patch 2014-08-06 16:12:24 -04:00
misc cmd/go: add '_go_' suffix to go files compiled by gccgo to avoid naming conflicts 2014-10-15 13:13:37 -07:00
src cmd/gc: simplify compiled code for explicit zeroing 2014-10-15 19:33:15 -04:00
test cmd/gc: blank methods are not permitted in interface types 2014-10-15 09:55:13 -07:00
.hgignore .hgignore: delete some dregs 2014-09-25 17:30:12 -07:00
.hgtags tag go1.3.3 2014-10-01 13:38:00 +10:00
AUTHORS A+C: Ron Hashimoto (individual CLA) 2014-10-08 07:10:04 -07:00
CONTRIBUTORS C: add Hana Kim (Google CLA) 2014-10-09 15:00:23 +02:00
favicon.ico godoc: update favicon 2012-10-11 17:02:36 +11:00
LICENSE doc: update licensing text one more time 2012-03-27 15:09:13 +11:00
PATENTS LICENSE: separate, change PATENTS text 2010-12-06 16:31:59 -05:00
README README: Fix installation instructions 2013-11-20 13:47:37 -08:00
robots.txt godoc: serve robots.txt raw 2011-02-19 05:46:20 +11:00

This is the source code repository for the Go programming language.  

For documentation about how to install and use Go,
visit http://golang.org/ or load doc/install-source.html
in your web browser.

After installing Go, you can view a nicely formatted
doc/install-source.html by running godoc --http=:6060
and then visiting http://localhost:6060/doc/install/source.

Unless otherwise noted, the Go source files are distributed
under the BSD-style license found in the LICENSE file.

--

Binary Distribution Notes

If you have just untarred a binary Go distribution, you need to set
the environment variable $GOROOT to the full path of the go
directory (the one containing this README).  You can omit the
variable if you unpack it into /usr/local/go, or if you rebuild
from sources by running all.bash (see doc/install.html).
You should also add the Go binary directory $GOROOT/bin
to your shell's path.

For example, if you extracted the tar file into $HOME/go, you might
put the following in your .profile:

    export GOROOT=$HOME/go
    export PATH=$PATH:$GOROOT/bin

See doc/install.html for more details.