It is currently possible in the compiler to create a struct type,
calculate the widths of types that depend on it,
and then alter the struct type.

transformclosure has local protection against this.
Protect against it at a deeper level.

This is preparation to call dowidth automatically,
rather than explicitly.

Change-Id: Ic1578ca014610197cfe54a9f4d044d122a7217e8
Reviewed-on: https://go-review.googlesource.com/38469
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Change-Id: I9e52a2c52b754568412d719b415f91a998d247fe
Reviewed-on: https://go-review.googlesource.com/38467
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: If5eabd622700a6b82dc4961ae9174c9d907eedb7
Reviewed-on: https://go-review.googlesource.com/38465
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

In livenessepilogue, if we save liveness information for instructions
before updating liveout, we can avoid an extra bitvector temporary and
some extra copying around.

Passes toolstash-check -all.

Change-Id: I10d5803167ef3eba2e9e95094adc7e3d33929cc7
Reviewed-on: https://go-review.googlesource.com/38408Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

In some newer Linux distros, systemd forces
all mount namespaces to be shared, starting
at /. This disables the CLONE_NEWNS
flag in unshare(2) and clone(2).
While this problem is most commonly seen
on systems with systemd, it can happen anywhere,
due to how Linux namespaces now work.

Hence, to create a private mount namespace,
it is not sufficient to just set
CLONE_NEWS; you have to call mount(2) to change
the behavior of namespaces, i.e.
mount("none", "/", NULL, MS_REC|MS_PRIVATE, NULL)

This is tested and working and we can now correctly
start child process with private namespaces on Linux
distros that use systemd.

The new test works correctly on Ubuntu 16.04.2 LTS.
It fails if I comment out the new Mount, and
succeeds otherwise. In each case it correctly
cleans up after itself.

Fixes #19661

Change-Id: I52240b59628e3772b529d9bbef7166606b0c157d
Reviewed-on: https://go-review.googlesource.com/38471Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

A -0 constant is the same as 0. Use explicit negative zero
for float64 -0.0. Also, fix two test cases that were wrong.

Fixes #19673.

Change-Id: Ic09775f29d9bc2ee7814172e59c4a693441ea730
Reviewed-on: https://go-review.googlesource.com/38463
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

CL 38337 modified canMergeLoad to reject loads with multiple uses
so it is no longer necessary to check this in the SSA rules.

Change-Id: I03498390e778da1be8cb59ae0948e99289008315
Reviewed-on: https://go-review.googlesource.com/38473
Run-TryBot: Michael Munday <munday@ca.ibm.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Introduce a new type, gc.Progs, to manage
generation of Progs for a function.
Use it to replace globals pc and pcloc.

Passes toolstash-check -all.

Updates #15756

Change-Id: I2206998d7c58fe2a76b620904909f2e1cec8a57d
Reviewed-on: https://go-review.googlesource.com/38418
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Regalloc uses loop depths - make sure they are initialized!

Test to make sure we aren't pushing spills into loops.

This fixes a generated-code performance bug introduced with
the better spill placement change:
https://go-review.googlesource.com/c/34822/

Update #19595

Change-Id: Ib9f0da6fb588503518847d7aab51e569fd3fa61e
Reviewed-on: https://go-review.googlesource.com/38434Reviewed-by: David Chase <drchase@google.com>

We want to merge a load and op into a single instruction

    l = LOAD ptr mem
    y = OP x l

into

    y = OPload x ptr mem

However, all of our OPload instructions require that y uses
the same register as x. If x is needed past this instruction, then
we must copy x somewhere else, losing the whole benefit of merging
the instructions in the first place.

Disable this optimization if x is live past the OP.

Also disable this optimization if the OP is in a deeper loop than the load.

Update #19595

Change-Id: I87f596aad7e91c9127bfb4705cbae47106e1e77a
Reviewed-on: https://go-review.googlesource.com/38337Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>

As #19357 reported,

TST has 3 different sub forms
TST $imme, Rx
TST Ry << imme, Rx
TST Ry << Rz, Rx

just like CMP/CMN/TEQ has. But current arm assembler assembles all TST
instructions wrongly. This patch fixes it and adds more tests.

Fixes #19357

Change-Id: Iafedccfaab2cbb2631e7acf259837a782e2e8e2f
Reviewed-on: https://go-review.googlesource.com/37662
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

It was already marked flaky for everything but the dashboard.
Remove that restriction. It's just flaky overall.

It's doing more harm than good.

Updates #13324

Change-Id: I36feff32a1b8681e77700f74b9c70cb4073268eb
Reviewed-on: https://go-review.googlesource.com/38459
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Fixes #19667.

Change-Id: Iaa71e2020af123c1bd3ac25e0b760956688e8bdf
Reviewed-on: https://go-review.googlesource.com/38458
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

exporter.nesting was added in c7b9bd74 to mitigate #16369 which was
closed in ee272bbf. Remove the exporter.nesting field as it is now unused.

Change-Id: I07873d1a07d6a08b11994b817a1483ffc2f5e45f
Reviewed-on: https://go-review.googlesource.com/38490
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

CL 38446 introduced the use of the sys.ArchFamily type into the
cmd/internal/obj/mips package and redefined the mips.Mips32 and
mips.Mips64 constants in terms of their sys.ArchFamily counterparts.
This CL removes these local declarations and consolidates on sys.MIPS
and sys.MIPS64 respectively.

Change-Id: Id7aab6c7fd0de42ff43dde605df6bd4c85a3d895
Reviewed-on: https://go-review.googlesource.com/38287Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The step method implementations check directly if the next rune
only needs one byte to be decoded and avoid calling utf8.DecodeRune
for such ASCII characters.

Introduce the same fast path optimization for rune decoding
for the context methods.

Results for regexp benchmarks that use the context methods:

name                            old time/op  new time/op  delta
AnchoredLiteralShortNonMatch-4  97.5ns ± 1%  94.8ns ± 2%  -2.80%  (p=0.000 n=45+43)
AnchoredShortMatch-4             163ns ± 1%   160ns ± 1%  -1.84%  (p=0.000 n=46+47)
NotOnePassShortA-4               742ns ± 2%   742ns ± 2%    ~     (p=0.440 n=49+50)
NotOnePassShortB-4               535ns ± 1%   533ns ± 2%  -0.37%  (p=0.005 n=46+48)
OnePassLongPrefix-4              169ns ± 2%   166ns ± 2%  -2.06%  (p=0.000 n=50+49)

Change-Id: Ib302d9e8c63333f02695369fcf9963974362e335
Reviewed-on: https://go-review.googlesource.com/38256Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

There were no allocations in regexp.Match for *non* onepass regex
because m.matchcap length is reset to zero (ncap=0 for regexp.Match).

But, as for onepass regex, m.matchcap length remains as it is even when
ncap=0 and it leads needless allocations.

benchmark                                    old ns/op      new ns/op      delta
BenchmarkMatch_onepass_regex/32-4      6465           4628           -28.41%
BenchmarkMatch_onepass_regex/1K-4      208324         151558         -27.25%
BenchmarkMatch_onepass_regex/32K-4     7230259        5834492        -19.30%
BenchmarkMatch_onepass_regex/1M-4      234379810      166310682      -29.04%
BenchmarkMatch_onepass_regex/32M-4     7903529363     4981119950     -36.98%

benchmark                                    old MB/s     new MB/s     speedup
BenchmarkMatch_onepass_regex/32-4      4.95         6.91         1.40x
BenchmarkMatch_onepass_regex/1K-4      4.92         6.76         1.37x
BenchmarkMatch_onepass_regex/32K-4     4.53         5.62         1.24x
BenchmarkMatch_onepass_regex/1M-4      4.47         6.30         1.41x
BenchmarkMatch_onepass_regex/32M-4     4.25         6.74         1.59x

benchmark                                    old allocs     new allocs     delta
BenchmarkMatch_onepass_regex/32-4      32             0              -100.00%
BenchmarkMatch_onepass_regex/1K-4      1024           0              -100.00%
BenchmarkMatch_onepass_regex/32K-4     32768          0              -100.00%
BenchmarkMatch_onepass_regex/1M-4      1048576        0              -100.00%
BenchmarkMatch_onepass_regex/32M-4     104559255      0              -100.00%

benchmark                                    old bytes      new bytes     delta
BenchmarkMatch_onepass_regex/32-4      512            0             -100.00%
BenchmarkMatch_onepass_regex/1K-4      16384          0             -100.00%
BenchmarkMatch_onepass_regex/32K-4     524288         0             -100.00%
BenchmarkMatch_onepass_regex/1M-4      16777216       0             -100.00%
BenchmarkMatch_onepass_regex/32M-4     2019458128     0             -100.00%

Fixes #19573

Change-Id: I033982d0003ebb0360bb40b92eb3941c781ec74d
Reviewed-on: https://go-review.googlesource.com/38270
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This greatly improves the latency of starting a child process when
the Go process is using a lot of memory. Even though the kernel uses
copy-on-write, preparation for that can take up to several 100ms under
certain conditions. All other goroutines are suspended while starting
a subprocess so this latency directly affects total throughput.

With CLONE_VM the child process shares the same memory with the parent
process. On its own this would lead to conflicting use of the same
memory, so CLONE_VFORK is used to suspend the parent process until the
child releases the memory when switching to to the new program binary
via the exec syscall. When the parent process continues to run, one
has to consider the changes to memory that the child process did,
namely the return address of the syscall function needs to be restored
from a register.

A simple benchmark has shown a difference in latency of 16ms vs. 0.5ms
at 10GB memory usage. However, much higher latencies of several 100ms
have been observed in real world scenarios. For more information see
comments on #5838.

Fixes #5838

Change-Id: I6377d7bd8dcd00c85ca0c52b6683e70ce2174ba6
Reviewed-on: https://go-review.googlesource.com/37439Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

When unmarshaling, if an element is empty, eg. '<tag></tag>', and
destination type is int, uint, float or bool, do not attempt to parse
value (""). Set to its zero value instead.

Fixes #13417

Change-Id: I2d79f6d8f39192bb277b1a9129727d5abbb2dd1f
Reviewed-on: https://go-review.googlesource.com/38386Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The DefaultServeMux included in net/http uses a map to store routes,
but iterates all keys for every request to allow longer paths.

This change checks the map for an exact match first.

To check performance was better, BenchmarkServeMux has been added -
this adds >100 routes and checks the matches.

Exact matches are faster and more predictable on this benchmark
and on most existing package benchmarks.

https://perf.golang.org/search?q=upload:20170312.1

ServeMux-4  2.02ms ± 2%	0.04ms ± 2%  −98.08%  (p=0.004 n=5+6)

https://perf.golang.org/search?q=upload:20170312.2

ReadRequestChrome-4	184MB/s  ± 8%	186MB/s  ± 1%	~
ReadRequestCurl-4	45.0MB/s ± 1%	46.2MB/s ± 1%	+2.71%
Read...Apachebench-4	45.8MB/s ±13%	48.7MB/s ± 1%	~
ReadRequestSiege-4	63.6MB/s ± 5%	69.2MB/s ± 1%	+8.75%
ReadRequestWrk-4	30.9MB/s ± 9%	34.4MB/s ± 2%	+11.25%

Change-Id: I8afafcb956f07197419d545a9f1c03ecaa307384
Reviewed-on: https://go-review.googlesource.com/38057Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This simplifies the code and removes a premature optimization.
It increases the amount of allocated syntax.Node space by ~0.4%
for parsing all of std lib, which is negligible.

Before the change (best of 5 runs):

  $ go test -run StdLib -fast
  parsed 1517022 lines (3394 files) in 793.487886ms (1911840 lines/s)
  allocated 387.086Mb (267B/line, 487.828Mb/s)

After the change (best of 5 runs):

  $ go test -run StdLib -fast
  parsed 1516911 lines (3392 files) in 805.028655ms (1884294 lines/s)
  allocated 388.466Mb (268B/line, 482.549Mb/s)

Change-Id: Id19d6210fdc62393862ba3b04913352d95c599be
Reviewed-on: https://go-review.googlesource.com/38439
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

This change adds position information for { and } braces in the
source. There's a 1.9% increase in memory use for syntax.Nodes,
which is negligible relative to overall compiler memory consumption.

Parsing the std library (using syntax package only) and memory
consumption before this change (fastest of 5 runs):

  $ go test -run StdLib -fast
  parsed 1516827 lines (3392 files) in 780.612335ms (1943124 lines/s)
  allocated 379.903Mb (486.673Mb/s)

After this change (fastest of 5 runs):

  $ go test -run StdLib -fast
  parsed 1517022 lines (3394 files) in 793.487886ms (1911840 lines/s)
  allocated 387.086Mb (267B/line, 487.828Mb/s)

While not an exact apples-to-apples comparison (the syntax package
has changed and is also parsed), the overall impact is small.

Also: Small improvements to nodes_test.go.

Change-Id: Ib8a7f90bbe79de33d83684e33b1bf8dbc32e644a
Reviewed-on: https://go-review.googlesource.com/38435Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Change-Id: I2d155c838935cd8427abd142a462ff4c56829715
Reviewed-on: https://go-review.googlesource.com/37948Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Ia739337dc9961422982912cc6a669022559fb991
Reviewed-on: https://go-review.googlesource.com/38365Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Preparation for eliminating Prog-related globals.

Passes toolstash-check -all.

Updates #15756

Change-Id: Ia199fcb282cc3a84903a6e92a3ce342c5faba79c
Reviewed-on: https://go-review.googlesource.com/38409
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Starting in go1.9, the minimum processor requirement for ppc64 is POWER8.
Therefore, the checks for OldArch and the code enabled by it are not necessary
anymore.

Updates #19074

Change-Id: I33d6a78b2462c80d57c5dbcba2e13424630afab4
Reviewed-on: https://go-review.googlesource.com/38404
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Starting in go1.9, the minimum processor requirement for ppc64 is POWER8. This
means the checks for GOARCH_ppc64 in asm_ppc64x.s can be removed, since we can
assume LBAR and STBCCC instructions (both from ISA 2.06) will always be
available.

Updates #19074

Change-Id: Ib4418169cd9fc6f871a5ab126b28ee58a2f349e2
Reviewed-on: https://go-review.googlesource.com/38406Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Ie22a08c93dfcfd4b336e7b158415448dd55b2c11
Reviewed-on: https://go-review.googlesource.com/38407
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Asmode is always set to p.Mode,
which is always set based on the arch family.
Instead, use the arch family directly.

Passes toolstash-check -all.

Change-Id: Id982472dcc8eeb6dd22cac5ad2f116b54a44caee
Reviewed-on: https://go-review.googlesource.com/38451
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Replace Ctxt.Mode with a method, Ctxt.RegWidth,
which is calculated directly off the arch info.

I believe that Prog.Mode can also be removed; future CL.

This is a step towards obj.Link immutability.

Passes toolstash-check -all.

Updates #15756

Change-Id: Ifd7f8f6ed0a2fdc032d1dd306fcd695a14aa5bc5
Reviewed-on: https://go-review.googlesource.com/38446
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Step one in eliminating Prog-related globals.

Passes toolstash-check -all.

Updates #15756

Change-Id: I3b777fb5a7716f2d9da3067fbd94c28ca894a465
Reviewed-on: https://go-review.googlesource.com/38450
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Fixes golang/go#19656

Change-Id: Ied20d3f25b6e147cc693a1dd1aeb9480adc6687e
Reviewed-on: https://go-review.googlesource.com/38405Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>

TestOnlyWriteTimeout assumes wrongly that:
- the Accept method of trackLastConnListener is called only once
- the shared variable conn never becomes nil
and crashes on some circumstances.

Updates #19032.

Change-Id: I61de22618cd90b84a2b6401afdb6e5d9b3336b12
Reviewed-on: https://go-review.googlesource.com/36735
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

To enable this, inline the call to nod and simplify.
Eliminates a reference to lineno from the backend.

Passes toolstash-check -all.

Updates #15756

Change-Id: I9c4bd77d10d727aa8f5e6c6bb16b0e05de165631
Reviewed-on: https://go-review.googlesource.com/38441
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Add docs.
Reduce indentation.

Passes toolstash-check -all.

Change-Id: I968d1af25989886ae9945052e05e211a107dde9c
Reviewed-on: https://go-review.googlesource.com/38443
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Benchmark results for GOARCH=amd64:

name                                     old time/op  new time/op  delta
FormatInt-4                              2.51µs ± 2%  2.40µs ± 2%   -4.51%  (p=0.000 n=9+10)
AppendInt-4                              1.67µs ± 2%  1.61µs ± 3%   -3.74%  (p=0.000 n=9+9)
FormatUint-4                              698ns ± 2%   643ns ± 3%   -7.95%  (p=0.000 n=10+8)
AppendUint-4                              478ns ± 1%   418ns ± 2%  -12.61%  (p=0.000 n=8+10)
AppendUintVarlen/1-4                     9.30ns ± 6%  9.15ns ± 1%     ~     (p=0.199 n=9+10)
AppendUintVarlen/12-4                    9.12ns ± 0%  9.16ns ± 2%     ~     (p=0.307 n=9+9)
AppendUintVarlen/123-4                   18.6ns ± 2%  18.7ns ± 0%     ~     (p=0.091 n=10+6)
AppendUintVarlen/1234-4                  19.1ns ± 4%  17.7ns ± 1%   -7.35%  (p=0.000 n=10+9)
AppendUintVarlen/12345-4                 21.5ns ± 3%  20.7ns ± 3%   -3.78%  (p=0.002 n=9+10)
AppendUintVarlen/123456-4                23.5ns ± 3%  20.9ns ± 1%  -11.14%  (p=0.000 n=10+9)
AppendUintVarlen/1234567-4               25.0ns ± 2%  23.6ns ± 7%   -5.48%  (p=0.004 n=9+10)
AppendUintVarlen/12345678-4              26.8ns ± 2%  23.4ns ± 2%  -12.79%  (p=0.000 n=9+10)
AppendUintVarlen/123456789-4             29.8ns ± 3%  26.5ns ± 5%  -11.03%  (p=0.000 n=10+10)
AppendUintVarlen/1234567890-4            31.6ns ± 3%  26.9ns ± 3%  -14.95%  (p=0.000 n=10+9)
AppendUintVarlen/12345678901-4           33.8ns ± 3%  29.3ns ± 5%  -13.21%  (p=0.000 n=10+10)
AppendUintVarlen/123456789012-4          35.5ns ± 4%  29.2ns ± 4%  -17.82%  (p=0.000 n=10+10)
AppendUintVarlen/1234567890123-4         37.6ns ± 4%  31.4ns ± 3%  -16.48%  (p=0.000 n=10+10)
AppendUintVarlen/12345678901234-4        39.8ns ± 6%  32.0ns ± 7%  -19.60%  (p=0.000 n=10+10)
AppendUintVarlen/123456789012345-4       40.7ns ± 0%  34.4ns ± 4%  -15.55%  (p=0.000 n=6+10)
AppendUintVarlen/1234567890123456-4      45.4ns ± 6%  35.1ns ± 4%  -22.66%  (p=0.000 n=10+10)
AppendUintVarlen/12345678901234567-4     45.1ns ± 1%  36.7ns ± 4%  -18.77%  (p=0.000 n=9+10)
AppendUintVarlen/123456789012345678-4    46.9ns ± 0%  36.4ns ± 3%  -22.49%  (p=0.000 n=9+10)
AppendUintVarlen/1234567890123456789-4   50.6ns ± 6%  38.8ns ± 3%  -23.28%  (p=0.000 n=10+10)
AppendUintVarlen/12345678901234567890-4  51.3ns ± 2%  38.4ns ± 0%  -25.00%  (p=0.000 n=9+8)

Benchmark results for GOARCH=386:

name                                     old time/op  new time/op  delta
FormatInt-4                              6.21µs ± 0%  6.14µs ± 0%  -1.11%  (p=0.008 n=5+5)
AppendInt-4                              4.95µs ± 0%  4.85µs ± 0%  -1.99%  (p=0.016 n=5+4)
FormatUint-4                             1.89µs ± 1%  1.83µs ± 1%  -2.94%  (p=0.008 n=5+5)
AppendUint-4                             1.59µs ± 0%  1.57µs ± 2%  -1.72%  (p=0.040 n=5+5)
FormatIntSmall-4                         8.48ns ± 0%  8.48ns ± 0%    ~     (p=0.905 n=5+5)
AppendIntSmall-4                         12.2ns ± 0%  12.2ns ± 0%    ~     (all equal)
AppendUintVarlen/1-4                     10.6ns ± 1%  10.7ns ± 0%    ~     (p=0.238 n=5+4)
AppendUintVarlen/12-4                    10.7ns ± 0%  10.7ns ± 1%    ~     (p=0.333 n=4+5)
AppendUintVarlen/123-4                   29.9ns ± 1%  30.2ns ± 0%  +1.07%  (p=0.016 n=5+4)
AppendUintVarlen/1234-4                  32.4ns ± 1%  30.4ns ± 0%  -6.30%  (p=0.008 n=5+5)
AppendUintVarlen/12345-4                 35.1ns ± 2%  34.9ns ± 0%    ~     (p=0.238 n=5+5)
AppendUintVarlen/123456-4                36.6ns ± 0%  35.3ns ± 0%  -3.55%  (p=0.029 n=4+4)
AppendUintVarlen/1234567-4               38.9ns ± 0%  39.6ns ± 0%  +1.80%  (p=0.029 n=4+4)
AppendUintVarlen/12345678-4              41.3ns ± 0%  40.1ns ± 0%  -2.91%  (p=0.000 n=5+4)
AppendUintVarlen/123456789-4             44.9ns ± 1%  44.8ns ± 0%    ~     (p=0.667 n=5+5)
AppendUintVarlen/1234567890-4            65.6ns ± 0%  66.2ns ± 1%  +0.88%  (p=0.016 n=4+5)
AppendUintVarlen/12345678901-4           77.9ns ± 0%  76.3ns ± 0%  -2.00%  (p=0.000 n=4+5)
AppendUintVarlen/123456789012-4          80.7ns ± 0%  79.1ns ± 1%  -2.01%  (p=0.008 n=5+5)
AppendUintVarlen/1234567890123-4         83.6ns ± 0%  80.2ns ± 1%  -4.07%  (p=0.008 n=5+5)
AppendUintVarlen/12345678901234-4        86.2ns ± 1%  83.3ns ± 0%  -3.39%  (p=0.008 n=5+5)
AppendUintVarlen/123456789012345-4       88.5ns ± 0%  83.7ns ± 0%  -5.42%  (p=0.008 n=5+5)
AppendUintVarlen/1234567890123456-4      90.6ns ± 0%  88.3ns ± 0%  -2.54%  (p=0.008 n=5+5)
AppendUintVarlen/12345678901234567-4     92.7ns ± 0%  89.0ns ± 1%  -4.01%  (p=0.008 n=5+5)
AppendUintVarlen/123456789012345678-4    95.6ns ± 1%  92.6ns ± 0%  -3.18%  (p=0.016 n=5+4)
AppendUintVarlen/1234567890123456789-4    118ns ± 0%   114ns ± 0%    ~     (p=0.079 n=4+5)
AppendUintVarlen/12345678901234567890-4   138ns ± 0%   136ns ± 0%  -1.45%  (p=0.008 n=5+5)

Updates #19445

Change-Id: Iafbe5c074898187c150dc3854e5b9fc19c10be05
Reviewed-on: https://go-review.googlesource.com/38255
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Coalesce identical cases.
Give it a proper doc comment.
Fix comment locations.
Update/delete old comments.

Passes toolstash-check -all.

Change-Id: I88d9cf20e6e04b0c1c6583e92cd96335831f183f
Reviewed-on: https://go-review.googlesource.com/38442
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

AMODE appears to have been intended to allow
a Prog to switch between 16 (!), 32, or 64 bit x86.
It is unused anywhere in the tree.

Passes toolstash-check -all.

Updates #15756

Change-Id: Ic57b257cfe580f29dad81d97e4193bf3c330c598
Reviewed-on: https://go-review.googlesource.com/38445
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

None of the following code uses it.

Passes toolstash-check -all.

Updates #15756

Change-Id: Ieeaaca8ba31e5c345c0c8a758d520b24be88e173
Reviewed-on: https://go-review.googlesource.com/38444
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

By analogy with the handling of methods on types, show the documentation
for a single field of a struct.

	% go doc ast.structtype.fields
	struct StructType {
	    Fields *FieldList  // list of field declarations
	}
	%

Fixes #19169.

Change-Id: I002f992e4aa64bee667e2e4bccc7082486149842
Reviewed-on: https://go-review.googlesource.com/38438Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>