Implement it through a partial order datastructure, which
keeps the relations between SSA values in a forest of DAGs
and is able to discover contradictions.

In make.bash, this patch is able to prove hundreds of conditions
which were not proved before.

Compilebench:

name       old time/op       new time/op       delta
Template         371ms ± 2%        368ms ± 1%    ~     (p=0.222 n=5+5)
Unicode          203ms ± 6%        199ms ± 3%    ~     (p=0.421 n=5+5)
GoTypes          1.17s ± 4%        1.18s ± 1%    ~     (p=0.151 n=5+5)
Compiler         5.54s ± 2%        5.59s ± 1%    ~     (p=0.548 n=5+5)
SSA              12.9s ± 2%        13.2s ± 1%  +2.96%  (p=0.032 n=5+5)
Flate            245ms ± 2%        247ms ± 3%    ~     (p=0.690 n=5+5)
GoParser         302ms ± 6%        302ms ± 4%    ~     (p=0.548 n=5+5)
Reflect          764ms ± 4%        773ms ± 3%    ~     (p=0.095 n=5+5)
Tar              354ms ± 6%        361ms ± 3%    ~     (p=0.222 n=5+5)
XML              434ms ± 3%        429ms ± 1%    ~     (p=0.421 n=5+5)
StdCmd           22.6s ± 1%        22.9s ± 1%  +1.40%  (p=0.032 n=5+5)

name       old user-time/op  new user-time/op  delta
Template         436ms ± 8%        426ms ± 5%    ~     (p=0.579 n=5+5)
Unicode          219ms ±15%        219ms ±12%    ~     (p=1.000 n=5+5)
GoTypes          1.47s ± 6%        1.53s ± 6%    ~     (p=0.222 n=5+5)
Compiler         7.26s ± 4%        7.40s ± 2%    ~     (p=0.389 n=5+5)
SSA              17.7s ± 4%        18.5s ± 4%  +4.13%  (p=0.032 n=5+5)
Flate            257ms ± 5%        268ms ± 9%    ~     (p=0.333 n=5+5)
GoParser         354ms ± 6%        348ms ± 6%    ~     (p=0.913 n=5+5)
Reflect          904ms ± 2%        944ms ± 4%    ~     (p=0.056 n=5+5)
Tar              398ms ±11%        430ms ± 7%    ~     (p=0.079 n=5+5)
XML              501ms ± 7%        489ms ± 5%    ~     (p=0.444 n=5+5)

name       old text-bytes    new text-bytes    delta
HelloSize        670kB ± 0%        670kB ± 0%  +0.00%  (p=0.008 n=5+5)
CmdGoSize       7.22MB ± 0%       7.21MB ± 0%  -0.07%  (p=0.008 n=5+5)

name       old data-bytes    new data-bytes    delta
HelloSize       9.88kB ± 0%       9.88kB ± 0%    ~     (all equal)
CmdGoSize        248kB ± 0%        248kB ± 0%  -0.06%  (p=0.008 n=5+5)

name       old bss-bytes     new bss-bytes     delta
HelloSize        125kB ± 0%        125kB ± 0%    ~     (all equal)
CmdGoSize        145kB ± 0%        144kB ± 0%  -0.20%  (p=0.008 n=5+5)

name       old exe-bytes     new exe-bytes     delta
HelloSize       1.43MB ± 0%       1.43MB ± 0%    ~     (all equal)
CmdGoSize       14.5MB ± 0%       14.5MB ± 0%  -0.06%  (p=0.008 n=5+5)

Fixes #19714
Updates #20393

Change-Id: Ia090f5b5dc1bcd274ba8a39b233c1e1ace1b330e
Reviewed-on: https://go-review.googlesource.com/100277
Run-TryBot: Giovanni Bajo <rasky@develer.com>
Reviewed-by: David Chase <drchase@google.com>

There are several things combined in this change.

First, eliminate the gobitvector type in favor
of adding a ptrbit method to bitvector.
In non-performance-critical code, use that method.
In performance critical code, though, load the bitvector data
one byte at a time and iterate only over set bits.
To support that, add and use sys.Ctz8.

name                old time/op  new time/op  delta
StackCopyPtr-8      81.8ms ± 5%  78.9ms ± 3%   -3.58%  (p=0.000 n=97+96)
StackCopy-8         65.9ms ± 3%  62.8ms ± 3%   -4.67%  (p=0.000 n=96+92)
StackCopyNoCache-8   105ms ± 3%   102ms ± 3%   -3.38%  (p=0.000 n=96+95)

Change-Id: I00b80f45612708bd440b1a411a57fa6dfa24aa74
Reviewed-on: https://go-review.googlesource.com/109716
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

getArgInfo is called a lot during stack copying.
In the common case it doesn't do much work,
but it cannot be inlined.

This change works around that.

name                old time/op  new time/op  delta
StackCopyPtr-8       108ms ± 5%    96ms ± 4%  -10.40%  (p=0.000 n=20+20)
StackCopy-8         82.6ms ± 3%  78.4ms ± 6%   -5.15%  (p=0.000 n=19+20)
StackCopyNoCache-8   130ms ± 3%   122ms ± 3%   -6.44%  (p=0.000 n=20+20)

Change-Id: If7d8a08c50a4e2e76e4331b399396c5dbe88c2ce
Reviewed-on: https://go-review.googlesource.com/108945
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Currently, when the runtime looks up the stack map for a frame, it
uses frame.continpc - 1 unless continpc is the function entry PC, in
which case it uses frame.continpc. As a result, if continpc is the
function entry point (which happens for deferred frames), it will
actually look up the stack map *following* the first instruction.

I think, though I am not positive, that this is always okay today
because the first instruction of a function can never change the stack
map. It's usually not a CALL, so it doesn't have PCDATA. Or, if it is
a CALL, it has to have the entry stack map.

But we're about to start emitting stack maps at every instruction that
changes them, which means the first instruction can have PCDATA
(notably, in leaf functions that don't have a prologue).

To prepare for this, tweak how the runtime looks up stack map indexes
so that if continpc is the function entry point, it directly uses the
entry stack map.

For #24543.

Change-Id: I85aa818041cd26aff416f7b1fba186e9c8ca6568
Reviewed-on: https://go-review.googlesource.com/109349Reviewed-by: Rick Hudson <rlh@golang.org>

This instruction was introduced on the z14 to accelerate "limbified"
multiplications for certain cryptographic algorithms. This change allows
it to be used in Go assembly.

Change-Id: Ic93dae7fec1756f662874c08a5abc435bce9dd9e
Reviewed-on: https://go-review.googlesource.com/109695
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Current optab entries are unordered, because the new instructions
are added at the end of the optab. The patch reorders them by comments
in optab, such as arithmetic operations, logical operations and a
series of load/store etc.

The patch removes the VMOVS opcode because FMOVS already has the same
operation.

Change-Id: Iccdf89ecbb3875b9dfcb6e06be2cc19c7e5581a2
Reviewed-on: https://go-review.googlesource.com/109896
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Return a non-zero exit code if the WebAssembly host fails to compile
the WebAssmbly bytecode to machine code.

Change-Id: I774309db2872b6a2de77a1b0392608058414160d
Reviewed-on: https://go-review.googlesource.com/110097Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

ARM64 supports efficient instructions which combine shift, addition, load/store
together. Such as "MOVD (R0)(R1<<3), R2" and "MOVWU R6, (R4)(R1<<2)".

This CL optimizes the compiler to emit such efficient instuctions. And below
is some test data.

1. binary size before/after
binary                 size change
pkg/linux_arm64        +80.1KB
pkg/tool/linux_arm64   +121.9KB
go                     -4.3KB
gofmt                  -64KB

2. go1 benchmark
There is big improvement for the test case Fannkuch11, and slight
improvement for sme others, excluding noise.

name                     old time/op    new time/op    delta
BinaryTree17-4              43.9s ± 2%     44.0s ± 2%     ~     (p=0.820 n=30+30)
Fannkuch11-4                30.6s ± 2%     24.5s ± 3%  -19.93%  (p=0.000 n=25+30)
FmtFprintfEmpty-4           500ns ± 0%     499ns ± 0%   -0.11%  (p=0.000 n=23+25)
FmtFprintfString-4         1.03µs ± 0%    1.04µs ± 3%     ~     (p=0.065 n=29+30)
FmtFprintfInt-4            1.15µs ± 3%    1.15µs ± 4%   -0.56%  (p=0.000 n=30+30)
FmtFprintfIntInt-4         1.80µs ± 5%    1.82µs ± 0%     ~     (p=0.094 n=30+24)
FmtFprintfPrefixedInt-4    2.17µs ± 5%    2.20µs ± 0%     ~     (p=0.100 n=30+23)
FmtFprintfFloat-4          3.08µs ± 3%    3.09µs ± 4%     ~     (p=0.123 n=30+30)
FmtManyArgs-4              7.41µs ± 4%    7.17µs ± 1%   -3.26%  (p=0.000 n=30+23)
GobDecode-4                93.7ms ± 0%    94.7ms ± 4%     ~     (p=0.685 n=24+30)
GobEncode-4                78.7ms ± 7%    77.1ms ± 0%     ~     (p=0.729 n=30+23)
Gzip-4                      4.01s ± 0%     3.97s ± 5%   -1.11%  (p=0.037 n=24+30)
Gunzip-4                    389ms ± 4%     384ms ± 0%     ~     (p=0.155 n=30+23)
HTTPClientServer-4          536µs ± 1%     537µs ± 1%     ~     (p=0.236 n=30+30)
JSONEncode-4                179ms ± 1%     182ms ± 6%     ~     (p=0.763 n=24+30)
JSONDecode-4                843ms ± 0%     839ms ± 6%   -0.42%  (p=0.003 n=25+30)
Mandelbrot200-4            46.5ms ± 0%    46.5ms ± 0%   +0.02%  (p=0.000 n=26+26)
GoParse-4                  44.3ms ± 6%    43.3ms ± 0%     ~     (p=0.067 n=30+27)
RegexpMatchEasy0_32-4      1.07µs ± 7%    1.07µs ± 4%     ~     (p=0.835 n=30+30)
RegexpMatchEasy0_1K-4      5.51µs ± 0%    5.49µs ± 0%   -0.35%  (p=0.000 n=23+26)
RegexpMatchEasy1_32-4      1.01µs ± 0%    1.02µs ± 4%   +0.96%  (p=0.014 n=24+30)
RegexpMatchEasy1_1K-4      7.43µs ± 0%    7.18µs ± 0%   -3.41%  (p=0.000 n=23+24)
RegexpMatchMedium_32-4     1.78µs ± 0%    1.81µs ± 4%   +1.47%  (p=0.012 n=23+30)
RegexpMatchMedium_1K-4      547µs ± 1%     542µs ± 3%   -0.90%  (p=0.003 n=24+30)
RegexpMatchHard_32-4       30.4µs ± 0%    29.7µs ± 0%   -2.15%  (p=0.000 n=19+23)
RegexpMatchHard_1K-4        913µs ± 0%     915µs ± 6%   +0.25%  (p=0.012 n=24+30)
Revcomp-4                   6.32s ± 1%     6.42s ± 4%     ~     (p=0.342 n=25+30)
Template-4                  868ms ± 6%     878ms ± 6%   +1.15%  (p=0.000 n=30+30)
TimeParse-4                4.57µs ± 4%    4.59µs ± 3%   +0.65%  (p=0.010 n=29+30)
TimeFormat-4               4.51µs ± 0%    4.50µs ± 0%   -0.27%  (p=0.000 n=27+24)
[Geo mean]                  695µs          689µs        -0.92%

name                     old speed      new speed      delta
GobDecode-4              8.19MB/s ± 0%  8.12MB/s ± 4%     ~     (p=0.680 n=24+30)
GobEncode-4              9.76MB/s ± 7%  9.96MB/s ± 0%     ~     (p=0.616 n=30+23)
Gzip-4                   4.84MB/s ± 0%  4.89MB/s ± 4%   +1.16%  (p=0.030 n=24+30)
Gunzip-4                 49.9MB/s ± 4%  50.6MB/s ± 0%     ~     (p=0.162 n=30+23)
JSONEncode-4             10.9MB/s ± 1%  10.7MB/s ± 6%     ~     (p=0.575 n=24+30)
JSONDecode-4             2.30MB/s ± 0%  2.32MB/s ± 5%   +0.72%  (p=0.003 n=22+30)
GoParse-4                1.31MB/s ± 6%  1.34MB/s ± 0%   +2.26%  (p=0.002 n=30+27)
RegexpMatchEasy0_32-4    30.0MB/s ± 6%  30.0MB/s ± 4%     ~     (p=1.000 n=30+30)
RegexpMatchEasy0_1K-4     186MB/s ± 0%   187MB/s ± 0%   +0.35%  (p=0.000 n=23+26)
RegexpMatchEasy1_32-4    31.8MB/s ± 0%  31.5MB/s ± 4%   -0.92%  (p=0.012 n=25+30)
RegexpMatchEasy1_1K-4     138MB/s ± 0%   143MB/s ± 0%   +3.53%  (p=0.000 n=23+24)
RegexpMatchMedium_32-4    560kB/s ± 0%   553kB/s ± 4%   -1.19%  (p=0.005 n=23+30)
RegexpMatchMedium_1K-4   1.87MB/s ± 0%  1.89MB/s ± 3%   +1.04%  (p=0.002 n=24+30)
RegexpMatchHard_32-4     1.05MB/s ± 0%  1.08MB/s ± 0%   +2.40%  (p=0.000 n=19+23)
RegexpMatchHard_1K-4     1.12MB/s ± 0%  1.12MB/s ± 5%   +0.12%  (p=0.006 n=25+30)
Revcomp-4                40.2MB/s ± 1%  39.6MB/s ± 4%     ~     (p=0.242 n=25+30)
Template-4               2.24MB/s ± 6%  2.21MB/s ± 6%   -1.15%  (p=0.000 n=30+30)
[Geo mean]               7.87MB/s       7.91MB/s        +0.44%

Change-Id: If374cb7abf83537aa0a176f73c0f736f7800db03
Reviewed-on: https://go-review.googlesource.com/108735Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The init function and runtime.addmoduledata were not added when
building plugin, which caused the runtime could not find the
module.

Testplugin is still not enabled on linux/arm64
(https://go.googlesource.com/go/+/master/src/cmd/dist/test.go#948)
because the gold linker on the builder is too old, which fails
with an internal error (see issue #17138). I tested locally and
it passes.

Fixes #24940.
Updates #17138.

Change-Id: I26aebca6c38a3443af0949471fa12b6d550e8c6c
Reviewed-on: https://go-review.googlesource.com/109917
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

mips64 softfloat support is based on mips implementation and introduces
new enviroment variable GOMIPS64.

GOMIPS64 is a GOARCH=mips64{,le} specific option, for a choice between
hard-float and soft-float. Valid values are 'hardfloat' (default) and
'softfloat'. It is passed to the assembler as
'GOMIPS64_{hardfloat,softfloat}'.

Change-Id: I7f73078627f7cb37c588a38fb5c997fe09c56134
Reviewed-on: https://go-review.googlesource.com/108475Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Hex before: d0 a1
Hex after: 43

Not sure where that came from.

Change-Id: I189e7e21f8faf480ba72846b956a149976f720f8
Reviewed-on: https://go-review.googlesource.com/109777Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I561640768c43491288e7f5bd1a34247787793dab
Reviewed-on: https://go-review.googlesource.com/109935Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #24999

Change-Id: Ie0bb6a6e0fa3992cdd272d42347af65ae7c95463
Reviewed-on: https://go-review.googlesource.com/108755
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

As a follow-up to the first README for cmd/compile/internal/ssa.

Since this is the parent package for all the compiler packages, this
README serves as an overview of the compiler and its packages. As more
READMEs are added for specific parts with more detail, such as ssa's,
they can be linked from this one.

Thanks to Iskander Sharipov, Josh Bleecher Snyder, Matthew Dempsky,
Alberto Donizetti, and Robert Griesemer for helping with all the details
in this document.

Change-Id: I820a535e25dce86ccc667ce1c6e92b75fc32f3af
Reviewed-on: https://go-review.googlesource.com/103935Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Not a big win, but cheap.

name        old alloc/op      new alloc/op      delta
Template         34.4MB ± 0%       34.4MB ± 0%  -0.20%  (p=0.000 n=15+15)
Unicode          29.2MB ± 0%       29.3MB ± 0%  +0.17%  (p=0.000 n=15+15)
GoTypes           113MB ± 0%        113MB ± 0%  -0.22%  (p=0.000 n=15+15)
Compiler          509MB ± 0%        508MB ± 0%  -0.11%  (p=0.000 n=15+14)
SSA              1.46GB ± 0%       1.46GB ± 0%  -0.08%  (p=0.000 n=14+15)
Flate            23.8MB ± 0%       23.7MB ± 0%  -0.22%  (p=0.000 n=15+15)
GoParser         27.9MB ± 0%       27.8MB ± 0%  -0.21%  (p=0.000 n=14+15)
Reflect          77.2MB ± 0%       77.0MB ± 0%  -0.27%  (p=0.000 n=14+15)
Tar              34.0MB ± 0%       33.9MB ± 0%  -0.21%  (p=0.000 n=13+15)
XML              42.6MB ± 0%       42.5MB ± 0%  -0.15%  (p=0.000 n=15+15)
[Geo mean]       75.8MB            75.7MB       -0.15%

name        old allocs/op     new allocs/op     delta
Template           322k ± 0%         320k ± 0%  -0.60%  (p=0.000 n=15+15)
Unicode            337k ± 0%         336k ± 0%  -0.23%  (p=0.000 n=12+15)
GoTypes           1.13M ± 0%        1.12M ± 0%  -0.58%  (p=0.000 n=15+14)
Compiler          4.67M ± 0%        4.65M ± 0%  -0.38%  (p=0.000 n=14+15)
SSA               11.7M ± 0%        11.6M ± 0%  -0.25%  (p=0.000 n=15+15)
Flate              216k ± 0%         214k ± 0%  -0.67%  (p=0.000 n=15+15)
GoParser           271k ± 0%         270k ± 0%  -0.57%  (p=0.000 n=15+15)
Reflect            927k ± 0%         920k ± 0%  -0.72%  (p=0.000 n=13+14)
Tar                318k ± 0%         316k ± 0%  -0.57%  (p=0.000 n=15+15)
XML                376k ± 0%         375k ± 0%  -0.46%  (p=0.000 n=14+14)
[Geo mean]         731k              727k       -0.50%

Change-Id: I1417c5881e866fb3efe62a3d0fbe1134275da31a
Reviewed-on: https://go-review.googlesource.com/109755
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

I forgot this in CL 109358.

Change-Id: Ia5e8bd9cf43393f098b101a0d6a0c526e3e4f101
Reviewed-on: https://go-review.googlesource.com/109775
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

If the vetted function supplies zero arguments, previously you would
get an error message like this:

    Printf format %v reads arg #1, but call has only 0 args

"has only 0 args" is an odd construction, and "has 0 args" sounds
better. Getting rid of "only" in all cases simplifies the code and
reads just as well.

Change-Id: I4706dfe4a75f13bf4db9c0650e459ca676710752
Reviewed-on: https://go-review.googlesource.com/109457
Run-TryBot: Kevin Burke <kev@inburke.com>
Run-TryBot: David Symonds <dsymonds@golang.org>
Reviewed-by: David Symonds <dsymonds@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Simplify some C-style loops with range statements, and move some
declarations closer to their uses.

While at it, ensure that all the SymbolType consts are typed.

Change-Id: I04b06afb2c1fb249ef8093a0c5cca0a597d1e05c
Reviewed-on: https://go-review.googlesource.com/105217
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Using oldname+resolve is how typecheck handles this anyway.

Passes toolstash -cmp, with both -iexport enabled and disabled.

Change-Id: I12b0f0333d6b86ce6bfc4d416c461b5f15c1110d
Reviewed-on: https://go-review.googlesource.com/109715
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Getcallerpc/sp no longer takes argument.

Change-Id: I80b30020e798990c59c8ffd0a4e078af6a75aea0
Reviewed-on: https://go-review.googlesource.com/109696Reviewed-by: Ian Lance Taylor <iant@golang.org>

Also change tasks to be represented as "slices" instead of
asynchronous events which are more efficiently represented in trace
viewer data model. This change allows to utilize the flow events
(arrows) to represent task hierarchies.

Introduced RegionArgs and TaskArgs where the task id infomation and
goroutine id informations are stored for information-purpose.

Change-Id: I11bec7dd716fdfc5f94ea39661b2e51344367a6f
Reviewed-on: https://go-review.googlesource.com/109337Reviewed-by: Heschi Kreinick <heschi@google.com>

Change-Id: I919444886a264bc11026faa8ccda193bf09a8d8d
Reviewed-on: https://go-review.googlesource.com/109675Reviewed-by: Heschi Kreinick <heschi@google.com>

Change-Id: I220a459f67ecb310b6e9a526a1ff55527d421e70
Reviewed-on: https://go-review.googlesource.com/109416
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Fixes #24883.

Change-Id: Iff992ec3f2f31f4d82923d7cc806df4ee58e70b0
Reviewed-on: https://go-review.googlesource.com/108295
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Elias Naur <elias.naur@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

getcallersp is intrinsified, and so the dummy arg is no longer
needed. Remove it, as well as a few dummy args that are solely
to feed getcallersp.

Change-Id: Ibb6c948ff9c56537042b380ac3be3a91b247aaa6
Reviewed-on: https://go-review.googlesource.com/109596
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The example in the 'A web server' section of the effective Go document
uses Google's image charts API (at chart.apis.google.com).

The service is now deprecated (see developers.google.com/chart/image),
and visiting http://chart.apis.google.com gives a 404. The endpoint is
still active, so the Go code in the example still works, but there's
no point in making the link clickable by the user if the page returns
a 404.

Change the element to `<code>`.

Change-Id: Ie67f4723cfa636e3dc1460507055b6bbb2b0970c
Reviewed-on: https://go-review.googlesource.com/109576Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

'%SystemRoot%/System32/chcp.com' is a tool on Windows that
is used to change the active code page in the console.

'go test os/exec' can fail with:
"'chcp' is not recognized as an internal or external command"

The test uses a custom PATH variable but does not include
'%SystemRoot%/System32'. Always append that to PATH.

Updates #24709

Change-Id: I1ab83b326072e3f0086b391b836234bcfd8a1fb7
GitHub-Last-Rev: fb930529bb0673cdec921df5a2821c4b41de745e
GitHub-Pull-Request: golang/go#25088
Reviewed-on: https://go-review.googlesource.com/109361
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

'%SystemRoot%/System32/chcp.com' is a tool on Windows that
is used to change the active code page in the console.

'go test path/filepath' can fail with:
"'chcp' is not recognized as an internal or external command"

The test uses a custom PATH variable but does not include
'%SystemRoot%/System32'. Always append that to PATH.

Updates #24709

Change-Id: Ib4c83ffdcc5dd6eb7bb34c07386cf2ab61dcae57
GitHub-Last-Rev: fac92613cce0d60f6794ad850618ed64d04c76fd
GitHub-Pull-Request: golang/go#25089
Reviewed-on: https://go-review.googlesource.com/109362
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

On amd64, Ctz must include special handling of zeros.
But the prove pass has enough information to detect whether the input
is non-zero, allowing a more efficient lowering.

Introduce new CtzNonZero ops to capture and use this information.

Benchmark code:

func BenchmarkVisitBits(b *testing.B) {
	b.Run("8", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			x := uint8(0xff)
			for x != 0 {
				sink = bits.TrailingZeros8(x)
				x &= x - 1
			}
		}
	})

    // and similarly so for 16, 32, 64
}

name            old time/op  new time/op  delta
VisitBits/8-8   7.27ns ± 4%  5.58ns ± 4%  -23.35%  (p=0.000 n=28+26)
VisitBits/16-8  14.7ns ± 7%  10.5ns ± 4%  -28.43%  (p=0.000 n=30+28)
VisitBits/32-8  27.6ns ± 8%  19.3ns ± 3%  -30.14%  (p=0.000 n=30+26)
VisitBits/64-8  44.0ns ±11%  38.0ns ± 5%  -13.48%  (p=0.000 n=30+30)

Fixes #25077

Change-Id: Ie6e5bd86baf39ee8a4ca7cadcf56d934e047f957
Reviewed-on: https://go-review.googlesource.com/109358
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Running 'go run *.go' in the gen directory resulted in this diff.

Change-Id: Iee398a720f54d3f2c3c122fc6fc45a708a39e45e
Reviewed-on: https://go-review.googlesource.com/109575
Run-TryBot: Michael Munday <mike.munday@ibm.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #25106

Change-Id: I315817543b44aa581980828a32ecc224f8c0a44d
Reviewed-on: https://go-review.googlesource.com/109316Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

When creating a directory, Writer.Create now returns a dummy
io.Writer that always returns an error on Write.

Fixes #24043

Change-Id: I7792f54440d45d22d0aa174cba5015ed5fab1c5c
Reviewed-on: https://go-review.googlesource.com/108615Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

NewReplacer's documentation says that "replacements are performed in
order", meaning that substrings are replaced in the order they appear
in the target string, and not that the old->new replacements are
applied in the order they're passed to NewReplacer.

Rephrase the doc to make this clearer.

Fixes #25071

Change-Id: Icf3aa6a9d459b94764c9d577e4a76ad8c04d158d
Reviewed-on: https://go-review.googlesource.com/109375Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This change provides VSRI instruction for ChaCha20Poly1305 implementation.

Change-Id: Ifee727b6f3982b629b44a67cac5bbe87ca59027b
Reviewed-on: https://go-review.googlesource.com/109342
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Doesn't cause an error, see #25085.
But we should fix it nonetheless.

Change-Id: I7b6799e0a95475202cacefc3a7f02487e61bfd31
Reviewed-on: https://go-review.googlesource.com/109355Reviewed-by: Heschi Kreinick <heschi@google.com>

Use CMN/TST to simplify comparisons. This can reduce the
register pressure by removing single def/use registers for example:
ADDW R0, R1, R8 -> CMNW R1, R0 ; CMN is an alias of ADDS.
CBZW R8, label  -> BEQ  label  ; single def/use of R8 removed.

Little change in performance of go1 benchmark on Amberwing:
name                   old time/op    new time/op    delta
RegexpMatchEasy0_32       247ns ± 0%     246ns ± 0%  -0.40%  (p=0.008 n=5+5)
RegexpMatchEasy0_1K       581ns ± 0%     580ns ± 0%    ~     (p=0.079 n=4+5)
RegexpMatchEasy1_32       244ns ± 0%     243ns ± 0%  -0.41%  (p=0.008 n=5+5)
RegexpMatchEasy1_1K       804ns ± 0%     806ns ± 0%  +0.25%  (p=0.016 n=5+4)
RegexpMatchMedium_32      313ns ± 0%     311ns ± 0%  -0.64%  (p=0.008 n=5+5)
RegexpMatchMedium_1K     52.2µs ± 0%    51.9µs ± 0%  -0.51%  (p=0.008 n=5+5)
RegexpMatchHard_32       2.76µs ± 3%    2.74µs ± 0%    ~     (p=0.683 n=5+5)
RegexpMatchHard_1K       78.8µs ± 0%    78.9µs ± 0%  +0.04%  (p=0.008 n=5+5)
FmtFprintfEmpty          58.6ns ± 0%    57.7ns ± 0%  -1.54%  (p=0.008 n=5+5)
FmtFprintfString          118ns ± 0%     115ns ± 0%  -2.54%  (p=0.008 n=5+5)
FmtFprintfInt             119ns ± 0%     119ns ± 0%    ~     (all equal)
FmtFprintfIntInt          192ns ± 0%     192ns ± 0%    ~     (all equal)
FmtFprintfPrefixedInt     224ns ± 0%     205ns ± 0%  -8.48%  (p=0.008 n=5+5)
FmtFprintfFloat           336ns ± 0%     333ns ± 1%    ~     (p=0.683 n=5+5)
FmtManyArgs               779ns ± 1%     760ns ± 1%  -2.41%  (p=0.008 n=5+5)
Gzip                      437ms ± 0%     436ms ± 0%  -0.27%  (p=0.008 n=5+5)
HTTPClientServer         90.1µs ± 1%    91.1µs ± 0%  +1.19%  (p=0.008 n=5+5)
JSONEncode               20.1ms ± 0%    20.2ms ± 1%    ~     (p=0.690 n=5+5)
JSONDecode               94.5ms ± 1%    94.1ms ± 1%    ~     (p=0.095 n=5+5)
Mandelbrot200            5.37ms ± 0%    5.37ms ± 0%    ~     (p=0.421 n=5+5)
TimeParse                 450ns ± 0%     446ns ± 0%  -0.89%  (p=0.000 n=5+4)
TimeFormat                483ns ± 1%     473ns ± 0%  -2.19%  (p=0.008 n=5+5)
Template                 90.6ms ± 0%    89.7ms ± 0%  -0.93%  (p=0.008 n=5+5)
GoParse                  5.97ms ± 0%    6.01ms ± 0%  +0.65%  (p=0.008 n=5+5)
BinaryTree17              11.8s ± 0%     11.7s ± 0%  -0.28%  (p=0.016 n=5+5)
Revcomp                   669ms ± 0%     669ms ± 0%    ~     (p=0.222 n=5+5)
Fannkuch11                3.28s ± 0%     3.34s ± 0%  +1.72%  (p=0.016 n=4+5)
[Geo mean]               46.6µs         46.3µs       -0.74%

name                   old speed      new speed      delta
RegexpMatchEasy0_32     129MB/s ± 0%   130MB/s ± 0%  +0.32%  (p=0.016 n=5+4)
RegexpMatchEasy0_1K    1.76GB/s ± 0%  1.76GB/s ± 0%  +0.13%  (p=0.016 n=4+5)
RegexpMatchEasy1_32     131MB/s ± 0%   132MB/s ± 0%  +0.32%  (p=0.008 n=5+5)
RegexpMatchEasy1_1K    1.27GB/s ± 0%  1.27GB/s ± 0%  -0.24%  (p=0.016 n=5+4)
RegexpMatchMedium_32   3.19MB/s ± 0%  3.21MB/s ± 0%  +0.63%  (p=0.008 n=5+5)
RegexpMatchMedium_1K   19.6MB/s ± 0%  19.7MB/s ± 0%  +0.51%  (p=0.029 n=4+4)
RegexpMatchHard_32     11.6MB/s ± 2%  11.7MB/s ± 0%    ~     (p=1.000 n=5+5)
RegexpMatchHard_1K     13.0MB/s ± 0%  13.0MB/s ± 0%    ~     (p=0.079 n=4+5)
Gzip                   44.4MB/s ± 0%  44.5MB/s ± 0%  +0.27%  (p=0.008 n=5+5)
JSONEncode             96.4MB/s ± 0%  96.2MB/s ± 1%    ~     (p=0.579 n=5+5)
JSONDecode             20.5MB/s ± 1%  20.6MB/s ± 1%    ~     (p=0.111 n=5+5)
Template               21.4MB/s ± 0%  21.6MB/s ± 0%  +0.94%  (p=0.008 n=5+5)
GoParse                9.70MB/s ± 0%  9.63MB/s ± 0%  -0.68%  (p=0.016 n=4+5)
Revcomp                 380MB/s ± 0%   380MB/s ± 0%    ~     (p=0.222 n=5+5)
[Geo mean]             55.3MB/s       55.4MB/s       +0.23%

Change-Id: I2e5338138991d9bc984e67b51212aa5d1b0f2a6b
Reviewed-on: https://go-review.googlesource.com/97335Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>

This change implements math.Round as an intrinsic on ppc64x so it can be
done using a single instruction.

benchmark                   old ns/op     new ns/op     delta
BenchmarkRound-16           2.60          0.69          -73.46%

Change-Id: I9408363e96201abdfc73ced7bcd5f0c29db006a8
Reviewed-on: https://go-review.googlesource.com/109395
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>

When we moved racewalk to buildssa, we disabled SSA of structs with
2-4 fields while instrumenting because it caused false dependencies
because for "x.f" we would emit

    (StructSelect (Load (Addr x)) "f")

Even though we later simplify this to

    (Load (OffPtr (Addr x) "f"))

the instrumentation saw a load of x in its entirety and would issue
appropriate race/msan calls.

The fix taken here is to directly emit the OffPtr form when x.f is
addressable and can't be represented in SSA form.

Change-Id: I0caf37bced52e9c16937466b0ac8cab6d356e525
Reviewed-on: https://go-review.googlesource.com/109360
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

This is a followup for CL 93156.

Fixes #22942.

Change-Id: Ic6e2de44011d041b91454353a6f2e3b0cf590060
Reviewed-on: https://go-review.googlesource.com/108095
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Now that #18395 is fixed, let's see if we can insist
on vet during go test being able to type-check
packages again.

Change-Id: Iaa55a4d9c582ba743df2347d28c24f130e16e406
Reviewed-on: https://go-review.googlesource.com/108555
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>