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Dave Cheney 542dd8b9fb cmd/5g: peep.c: reactivate some optimisations 
Thanks to Minux and Remy for their advice.

The EOR optimisation is applied to a few places in the stdlib.

// hash/crc32/crc32.go
func update(crc uint32, tab *Table, p []byte) uint32 {
	crc = ^crc
	for _, v := range p {
        	crc = tab[byte(crc)^v] ^ (crc >> 8)
	}
	return ^crc
}

before:

--- prog list "update" ---
0164 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:101) TEXT        update+0(SB),$12-24
0165 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:101) MOVW        tab+4(FP),R8
0166 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:102) MOVW        crc+0(FP),R0
0167 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:102) EOR         $-1,R0,R5
0168 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:103) MOVW        p+8(FP),R0
0169 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:103) MOVW        R0,autotmp_0019+-12(SP)

after:

--- prog list "update" ---
0164 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:101) TEXT        update+0(SB),$12-24
0165 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:101) MOVW        tab+4(FP),R8
0166 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:102) MOVW        crc+0(FP),R0
0167 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:102) MVN         R0,R5
0168 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:103) MOVW        p+8(FP),R0
0169 (/home/dfc/go/src/pkg/hash/crc32/crc32.go:103) MOVW        R0,autotmp_0019+-12(SP)

After 5l has done its work,

        crc = ^crc
   3d710:       e59d0014        ldr     r0, [sp, #20]
   3d714:       e3e0b000        mvn     fp, #0
   3d718:       e020500b        eor     r5, r0, fp

becomes

        crc = ^crc
   3d710:       e59d0014        ldr     r0, [sp, #20]
   3d714:       e1e05000        mvn     r5, r0

The MOVB optimisation has a small impact on the stdlib, in strconv
and gzip.

// GZIP (RFC 1952) is little-endian, unlike ZLIB (RFC 1950).
func put2(p []byte, v uint16) {
        p[0] = uint8(v >> 0)
        p[1] = uint8(v >> 8)
}

before:

--- prog list "put2" ---
1369 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:76) TEXT       put2+0(SB),$0-16
1370 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:76) MOVHU      v+12(FP),R4
1371 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVHU      R4,R0
1372 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVHU      R0,R0
1373 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVBU      R0,R1
1374 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVBU      R1,R3
1375 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVW       $p+0(FP),R1

after:

--- prog list "put2" ---
1369 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:76) TEXT       put2+0(SB),$0-16
1370 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:76) MOVHU      v+12(FP),R4
1371 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVHU      R4,R0
1372 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVBU      R0,R1
1373 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVBU      R1,R3
1374 (/home/dfc/go/src/pkg/compress/gzip/gzip.go:77) MOVW       $p+0(FP),R1

R=remyoudompheng, rsc, minux.ma
CC=golang-dev
https://golang.org/cl/6674048
2012-10-26 18:19:10 +11:00
api cmd/api: add exception file 2012-10-04 11:35:17 +10:00
doc doc: remove misplaced articles from references page 2012-10-25 11:05:42 +11:00
include lib9, cmd/dist, cmd/5l: embed GOARM into cmd/5l and auto detect GOARM 2012-10-22 14:26:36 +08:00
lib codereview: protect against read-only upstream repository 2012-10-20 17:23:48 +08:00
misc gophertool: fix links 2012-10-22 01:05:21 +08:00
src cmd/5g: peep.c: reactivate some optimisations 2012-10-26 18:19:10 +11:00
test cmd/6g: fix crash in cgen_bmul. 2012-10-26 00:29:44 +02:00
.hgignore build: update Makefile to track source code dependencies better 2012-03-13 03:31:11 +08:00
.hgtags tag go1.0.3 2012-09-24 13:15:33 -05:00
AUTHORS A+C: Jingcheng Zhang and Patrick Smith (individual CLA x2) 2012-10-21 20:32:35 -04:00
CONTRIBUTORS A+C: Jingcheng Zhang and Patrick Smith (individual CLA x2) 2012-10-21 20:32:35 -04:00
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 build: update, streamline documentation for new $GOBIN 2010-08-24 20:00:50 -04:00
robots.txt godoc: serve robots.txt raw 2011-02-19 05:46:20 +11:00

README 

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.html in your web browser.

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

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.