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Russ Cox 4d0f3a1c95 cmd/internal/gc, runtime: use 1-bit bitmap for stack frames, data, bss 
The bitmaps were 2 bits per pointer because we needed to distinguish
scalar, pointer, multiword, and we used the leftover value to distinguish
uninitialized from scalar, even though the garbage collector (GC) didn't care.

Now that there are no multiword structures from the GC's point of view,
cut the bitmaps down to 1 bit per pointer, recording just live pointer vs not.

The GC assumes the same layout for stack frames and for the maps
describing the global data and bss sections, so change them all in one CL.

The code still refers to 4-bit heap bitmaps and 2-bit "type bitmaps", since
the 2-bit representation lives (at least for now) in some of the reflect data.

Because these stack frame bitmaps are stored directly in the rodata in
the binary, this CL reduces the size of the 6g binary by about 1.1%.

Performance change is basically a wash, but using less memory,
and smaller binaries, and enables other bitmap reductions.

name                                      old mean                new mean        delta
BenchmarkBinaryTree17                13.2s × (0.97,1.03)     13.0s × (0.99,1.01)  -0.93% (p=0.005)
BenchmarkBinaryTree17-2              9.69s × (0.96,1.05)     9.51s × (0.96,1.03)  -1.86% (p=0.001)
BenchmarkBinaryTree17-4              10.1s × (0.97,1.05)     10.0s × (0.96,1.05)  ~ (p=0.141)
BenchmarkFannkuch11                  4.35s × (0.99,1.01)     4.43s × (0.98,1.04)  +1.75% (p=0.001)
BenchmarkFannkuch11-2                4.31s × (0.99,1.03)     4.32s × (1.00,1.00)  ~ (p=0.095)
BenchmarkFannkuch11-4                4.32s × (0.99,1.02)     4.38s × (0.98,1.04)  +1.38% (p=0.008)
BenchmarkFmtFprintfEmpty            83.5ns × (0.97,1.10)    87.3ns × (0.92,1.11)  +4.55% (p=0.014)
BenchmarkFmtFprintfEmpty-2          81.8ns × (0.98,1.04)    82.5ns × (0.97,1.08)  ~ (p=0.364)
BenchmarkFmtFprintfEmpty-4          80.9ns × (0.99,1.01)    82.6ns × (0.97,1.08)  +2.12% (p=0.010)
BenchmarkFmtFprintfString            320ns × (0.95,1.04)     322ns × (0.97,1.05)  ~ (p=0.368)
BenchmarkFmtFprintfString-2          303ns × (0.97,1.04)     304ns × (0.97,1.04)  ~ (p=0.484)
BenchmarkFmtFprintfString-4          305ns × (0.97,1.05)     306ns × (0.98,1.05)  ~ (p=0.543)
BenchmarkFmtFprintfInt               311ns × (0.98,1.03)     319ns × (0.97,1.03)  +2.63% (p=0.000)
BenchmarkFmtFprintfInt-2             297ns × (0.98,1.04)     301ns × (0.97,1.04)  +1.19% (p=0.023)
BenchmarkFmtFprintfInt-4             302ns × (0.98,1.02)     304ns × (0.97,1.03)  ~ (p=0.126)
BenchmarkFmtFprintfIntInt            554ns × (0.96,1.05)     554ns × (0.97,1.03)  ~ (p=0.975)
BenchmarkFmtFprintfIntInt-2          520ns × (0.98,1.03)     517ns × (0.98,1.02)  ~ (p=0.153)
BenchmarkFmtFprintfIntInt-4          524ns × (0.98,1.02)     525ns × (0.98,1.03)  ~ (p=0.597)
BenchmarkFmtFprintfPrefixedInt       433ns × (0.97,1.06)     434ns × (0.97,1.06)  ~ (p=0.804)
BenchmarkFmtFprintfPrefixedInt-2     413ns × (0.98,1.04)     413ns × (0.98,1.03)  ~ (p=0.881)
BenchmarkFmtFprintfPrefixedInt-4     420ns × (0.97,1.03)     421ns × (0.97,1.03)  ~ (p=0.561)
BenchmarkFmtFprintfFloat             620ns × (0.99,1.03)     636ns × (0.97,1.03)  +2.57% (p=0.000)
BenchmarkFmtFprintfFloat-2           601ns × (0.98,1.02)     617ns × (0.98,1.03)  +2.58% (p=0.000)
BenchmarkFmtFprintfFloat-4           613ns × (0.98,1.03)     626ns × (0.98,1.02)  +2.15% (p=0.000)
BenchmarkFmtManyArgs                2.19µs × (0.96,1.04)    2.23µs × (0.97,1.02)  +1.65% (p=0.000)
BenchmarkFmtManyArgs-2              2.08µs × (0.98,1.03)    2.10µs × (0.99,1.02)  +0.79% (p=0.019)
BenchmarkFmtManyArgs-4              2.10µs × (0.98,1.02)    2.13µs × (0.98,1.02)  +1.72% (p=0.000)
BenchmarkGobDecode                  21.3ms × (0.97,1.05)    21.1ms × (0.97,1.04)  -1.36% (p=0.025)
BenchmarkGobDecode-2                20.0ms × (0.97,1.03)    19.2ms × (0.97,1.03)  -4.00% (p=0.000)
BenchmarkGobDecode-4                19.5ms × (0.99,1.02)    19.0ms × (0.99,1.01)  -2.39% (p=0.000)
BenchmarkGobEncode                  18.3ms × (0.95,1.07)    18.1ms × (0.96,1.08)  ~ (p=0.305)
BenchmarkGobEncode-2                16.8ms × (0.97,1.02)    16.4ms × (0.98,1.02)  -2.79% (p=0.000)
BenchmarkGobEncode-4                15.4ms × (0.98,1.02)    15.4ms × (0.98,1.02)  ~ (p=0.465)
BenchmarkGzip                        650ms × (0.98,1.03)     655ms × (0.97,1.04)  ~ (p=0.075)
BenchmarkGzip-2                      652ms × (0.98,1.03)     655ms × (0.98,1.02)  ~ (p=0.337)
BenchmarkGzip-4                      656ms × (0.98,1.04)     653ms × (0.98,1.03)  ~ (p=0.291)
BenchmarkGunzip                      143ms × (1.00,1.01)     143ms × (1.00,1.01)  ~ (p=0.507)
BenchmarkGunzip-2                    143ms × (1.00,1.01)     143ms × (1.00,1.01)  ~ (p=0.313)
BenchmarkGunzip-4                    143ms × (1.00,1.01)     143ms × (1.00,1.01)  ~ (p=0.312)
BenchmarkHTTPClientServer            110µs × (0.98,1.03)     109µs × (0.99,1.02)  -1.40% (p=0.000)
BenchmarkHTTPClientServer-2          154µs × (0.90,1.08)     149µs × (0.90,1.08)  -3.43% (p=0.007)
BenchmarkHTTPClientServer-4          138µs × (0.97,1.04)     138µs × (0.96,1.04)  ~ (p=0.670)
BenchmarkJSONEncode                 40.2ms × (0.98,1.02)    40.2ms × (0.98,1.05)  ~ (p=0.828)
BenchmarkJSONEncode-2               35.1ms × (0.99,1.02)    35.2ms × (0.98,1.03)  ~ (p=0.392)
BenchmarkJSONEncode-4               35.3ms × (0.98,1.03)    35.3ms × (0.98,1.02)  ~ (p=0.813)
BenchmarkJSONDecode                  119ms × (0.97,1.02)     117ms × (0.98,1.02)  -1.80% (p=0.000)
BenchmarkJSONDecode-2                115ms × (0.99,1.02)     114ms × (0.98,1.02)  -1.18% (p=0.000)
BenchmarkJSONDecode-4                116ms × (0.98,1.02)     114ms × (0.98,1.02)  -1.43% (p=0.000)
BenchmarkMandelbrot200              6.03ms × (1.00,1.01)    6.03ms × (1.00,1.01)  ~ (p=0.985)
BenchmarkMandelbrot200-2            6.03ms × (1.00,1.01)    6.02ms × (1.00,1.01)  ~ (p=0.320)
BenchmarkMandelbrot200-4            6.03ms × (1.00,1.01)    6.03ms × (1.00,1.01)  ~ (p=0.799)
BenchmarkGoParse                    8.63ms × (0.89,1.10)    8.58ms × (0.93,1.09)  ~ (p=0.667)
BenchmarkGoParse-2                  8.20ms × (0.97,1.04)    8.37ms × (0.97,1.04)  +1.96% (p=0.001)
BenchmarkGoParse-4                  8.00ms × (0.98,1.02)    8.14ms × (0.99,1.02)  +1.75% (p=0.000)
BenchmarkRegexpMatchEasy0_32         162ns × (1.00,1.01)     164ns × (0.98,1.04)  +1.35% (p=0.011)
BenchmarkRegexpMatchEasy0_32-2       161ns × (1.00,1.01)     161ns × (1.00,1.00)  ~ (p=0.185)
BenchmarkRegexpMatchEasy0_32-4       161ns × (1.00,1.00)     161ns × (1.00,1.00)  -0.19% (p=0.001)
BenchmarkRegexpMatchEasy0_1K         540ns × (0.99,1.02)     566ns × (0.98,1.04)  +4.98% (p=0.000)
BenchmarkRegexpMatchEasy0_1K-2       540ns × (0.99,1.01)     557ns × (0.99,1.01)  +3.21% (p=0.000)
BenchmarkRegexpMatchEasy0_1K-4       541ns × (0.99,1.01)     559ns × (0.99,1.01)  +3.26% (p=0.000)
BenchmarkRegexpMatchEasy1_32         139ns × (0.98,1.04)     139ns × (0.99,1.03)  ~ (p=0.979)
BenchmarkRegexpMatchEasy1_32-2       139ns × (0.99,1.04)     139ns × (0.99,1.02)  ~ (p=0.777)
BenchmarkRegexpMatchEasy1_32-4       139ns × (0.98,1.04)     139ns × (0.99,1.04)  ~ (p=0.771)
BenchmarkRegexpMatchEasy1_1K         890ns × (0.99,1.03)     885ns × (1.00,1.01)  -0.50% (p=0.004)
BenchmarkRegexpMatchEasy1_1K-2       888ns × (0.99,1.01)     885ns × (0.99,1.01)  -0.37% (p=0.004)
BenchmarkRegexpMatchEasy1_1K-4       890ns × (0.99,1.02)     884ns × (1.00,1.00)  -0.70% (p=0.000)
BenchmarkRegexpMatchMedium_32        252ns × (0.99,1.01)     251ns × (0.99,1.01)  ~ (p=0.081)
BenchmarkRegexpMatchMedium_32-2      254ns × (0.99,1.04)     252ns × (0.99,1.01)  -0.78% (p=0.027)
BenchmarkRegexpMatchMedium_32-4      253ns × (0.99,1.04)     252ns × (0.99,1.01)  -0.70% (p=0.022)
BenchmarkRegexpMatchMedium_1K       72.9µs × (0.99,1.01)    72.7µs × (1.00,1.00)  ~ (p=0.064)
BenchmarkRegexpMatchMedium_1K-2     74.1µs × (0.98,1.05)    72.9µs × (1.00,1.01)  -1.61% (p=0.001)
BenchmarkRegexpMatchMedium_1K-4     73.6µs × (0.99,1.05)    72.8µs × (1.00,1.00)  -1.13% (p=0.007)
BenchmarkRegexpMatchHard_32         3.88µs × (0.99,1.03)    3.92µs × (0.98,1.05)  ~ (p=0.143)
BenchmarkRegexpMatchHard_32-2       3.89µs × (0.99,1.03)    3.93µs × (0.98,1.09)  ~ (p=0.278)
BenchmarkRegexpMatchHard_32-4       3.90µs × (0.99,1.05)    3.93µs × (0.98,1.05)  ~ (p=0.252)
BenchmarkRegexpMatchHard_1K          118µs × (0.99,1.01)     117µs × (0.99,1.02)  -0.54% (p=0.003)
BenchmarkRegexpMatchHard_1K-2        118µs × (0.99,1.01)     118µs × (0.99,1.03)  ~ (p=0.581)
BenchmarkRegexpMatchHard_1K-4        118µs × (0.99,1.02)     117µs × (0.99,1.01)  -0.54% (p=0.002)
BenchmarkRevcomp                     991ms × (0.95,1.10)     989ms × (0.94,1.08)  ~ (p=0.879)
BenchmarkRevcomp-2                   978ms × (0.95,1.11)     962ms × (0.96,1.08)  ~ (p=0.257)
BenchmarkRevcomp-4                   979ms × (0.96,1.07)     974ms × (0.96,1.11)  ~ (p=0.678)
BenchmarkTemplate                    141ms × (0.99,1.02)     145ms × (0.99,1.02)  +2.75% (p=0.000)
BenchmarkTemplate-2                  135ms × (0.98,1.02)     138ms × (0.99,1.02)  +2.34% (p=0.000)
BenchmarkTemplate-4                  136ms × (0.98,1.02)     140ms × (0.99,1.02)  +2.71% (p=0.000)
BenchmarkTimeParse                   640ns × (0.99,1.01)     622ns × (0.99,1.01)  -2.88% (p=0.000)
BenchmarkTimeParse-2                 640ns × (0.99,1.01)     622ns × (1.00,1.00)  -2.81% (p=0.000)
BenchmarkTimeParse-4                 640ns × (1.00,1.01)     622ns × (0.99,1.01)  -2.82% (p=0.000)
BenchmarkTimeFormat                  730ns × (0.98,1.02)     731ns × (0.98,1.03)  ~ (p=0.767)
BenchmarkTimeFormat-2                709ns × (0.99,1.02)     707ns × (0.99,1.02)  ~ (p=0.347)
BenchmarkTimeFormat-4                717ns × (0.98,1.01)     718ns × (0.98,1.02)  ~ (p=0.793)

Change-Id: Ie779c47e912bf80eb918bafa13638bd8dfd6c2d9
Reviewed-on: https://go-review.googlesource.com/9406
Reviewed-by: Rick Hudson <rlh@golang.org>
 		2015-05-01 18:44:36 +00:00
api api: update next.txt 2015-04-11 07:13:48 +00:00
doc Revert "runtime/pprof: write heap statistics to heap profile always" 2015-05-01 15:56:20 +00:00
lib/time remove the obsolete lib/codereview. 2014-12-08 07:51:54 +00:00
misc misc/cgo/testcshared, misc/cgo/testshared: fix clang warnings and errors 2015-04-30 17:08:15 +00:00
src cmd/internal/gc, runtime: use 1-bit bitmap for stack frames, data, bss 2015-05-01 18:44:36 +00:00
test cmd/internal/gc: improve flow of input params to output params 2015-05-01 13:47:20 +00:00
.gitattributes .gitattributes: prevent all magic line ending changes 2014-12-12 23:14:54 +00:00
.gitignore .gitignore: ignore ARM64 build products 2015-03-16 18:44:22 +00:00
AUTHORS A+C: add another email address for Emil Hessman 2014-11-12 10:01:23 -08:00
CONTRIBUTING.md doc: direct people to the mailing list 2015-01-18 21:27:07 +00:00
CONTRIBUTORS C: add Nick Cooper (Google CLA). 2014-11-14 17:03:17 +11:00
LICENSE
…
PATENTS
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README.md doc: fix broken link in README 2015-02-19 05:50:57 +00:00
favicon.ico godoc: update favicon 2012-10-11 17:02:36 +11:00
robots.txt
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README.md

The Go Programming Language

Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.

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

Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.

Please report issues here: https://golang.org/issue/new

Go is the work of hundreds of contributors. We appreciate your help!

To contribute, please read the contribution guidelines: https://golang.org/doc/contribute.html

Please note that we do not use pull requests.

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--

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 file). 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-source.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 https://golang.org/doc/install or doc/install.html for more details.