CL 214239 improved type printing, but introduced performance regressions:
3-5% memory increase, 1-2% CPU time increase.

There were two primary sources of the memory regression:

* allocating a bytes.Buffer for every type to print
* always printing to that buffer, even when we could return a constant string

This change addresses both of those regressions.
The sync.Pool allows buffer re-use.
String interning prevents allocation for re-used strings.

It addresses some, but not all, of the CPU time regression.


Memory performance impact vs master:

name        old alloc/op      new alloc/op      delta
Template         37.6MB ± 0%       36.3MB ± 0%  -3.30%  (p=0.008 n=5+5)
Unicode          28.7MB ± 0%       28.3MB ± 0%  -1.55%  (p=0.008 n=5+5)
GoTypes           127MB ± 0%        122MB ± 0%  -4.38%  (p=0.008 n=5+5)
Compiler          584MB ± 0%        568MB ± 0%  -2.72%  (p=0.008 n=5+5)
SSA              1.99GB ± 0%       1.95GB ± 0%  -1.97%  (p=0.008 n=5+5)
Flate            23.5MB ± 0%       22.8MB ± 0%  -2.84%  (p=0.008 n=5+5)
GoParser         29.2MB ± 0%       28.0MB ± 0%  -4.17%  (p=0.008 n=5+5)
Reflect          81.9MB ± 0%       78.6MB ± 0%  -4.09%  (p=0.008 n=5+5)
Tar              35.3MB ± 0%       34.1MB ± 0%  -3.29%  (p=0.008 n=5+5)
XML              45.5MB ± 0%       44.3MB ± 0%  -2.61%  (p=0.008 n=5+5)
[Geo mean]       82.4MB            79.9MB       -3.09%

name        old allocs/op     new allocs/op     delta
Template           394k ± 0%         363k ± 0%  -7.73%  (p=0.008 n=5+5)
Unicode            340k ± 0%         329k ± 0%  -3.25%  (p=0.008 n=5+5)
GoTypes           1.41M ± 0%        1.28M ± 0%  -9.54%  (p=0.008 n=5+5)
Compiler          5.77M ± 0%        5.39M ± 0%  -6.58%  (p=0.008 n=5+5)
SSA               19.1M ± 0%        18.1M ± 0%  -5.13%  (p=0.008 n=5+5)
Flate              247k ± 0%         228k ± 0%  -7.50%  (p=0.008 n=5+5)
GoParser           325k ± 0%         295k ± 0%  -9.24%  (p=0.008 n=5+5)
Reflect           1.04M ± 0%        0.95M ± 0%  -8.48%  (p=0.008 n=5+5)
Tar                365k ± 0%         336k ± 0%  -7.93%  (p=0.008 n=5+5)
XML                449k ± 0%         417k ± 0%  -7.10%  (p=0.008 n=5+5)
[Geo mean]         882k              818k       -7.26%


Memory performance going from 52c44884,
which is the commit preceding CL 214239, to this change:

name        old alloc/op      new alloc/op      delta
Template         36.5MB ± 0%       36.3MB ± 0%  -0.37%  (p=0.008 n=5+5)
Unicode          28.3MB ± 0%       28.3MB ± 0%  -0.06%  (p=0.008 n=5+5)
GoTypes           123MB ± 0%        122MB ± 0%  -0.64%  (p=0.008 n=5+5)
Compiler          571MB ± 0%        568MB ± 0%  -0.51%  (p=0.008 n=5+5)
SSA              1.96GB ± 0%       1.95GB ± 0%  -0.13%  (p=0.008 n=5+5)
Flate            22.8MB ± 0%       22.8MB ± 0%    ~     (p=0.421 n=5+5)
GoParser         28.1MB ± 0%       28.0MB ± 0%  -0.37%  (p=0.008 n=5+5)
Reflect          78.8MB ± 0%       78.6MB ± 0%  -0.32%  (p=0.008 n=5+5)
Tar              34.3MB ± 0%       34.1MB ± 0%  -0.35%  (p=0.008 n=5+5)
XML              44.3MB ± 0%       44.3MB ± 0%  +0.05%  (p=0.032 n=5+5)
[Geo mean]       80.1MB            79.9MB       -0.27%

name        old allocs/op     new allocs/op     delta
Template           372k ± 0%         363k ± 0%  -2.46%  (p=0.008 n=5+5)
Unicode            333k ± 0%         329k ± 0%  -0.97%  (p=0.008 n=5+5)
GoTypes           1.33M ± 0%        1.28M ± 0%  -3.71%  (p=0.008 n=5+5)
Compiler          5.53M ± 0%        5.39M ± 0%  -2.50%  (p=0.008 n=5+5)
SSA               18.3M ± 0%        18.1M ± 0%  -1.22%  (p=0.008 n=5+5)
Flate              234k ± 0%         228k ± 0%  -2.44%  (p=0.008 n=5+5)
GoParser           305k ± 0%         295k ± 0%  -3.23%  (p=0.008 n=5+5)
Reflect            980k ± 0%         949k ± 0%  -3.12%  (p=0.008 n=5+5)
Tar                345k ± 0%         336k ± 0%  -2.69%  (p=0.008 n=5+5)
XML                425k ± 0%         417k ± 0%  -1.72%  (p=0.008 n=5+5)
[Geo mean]         838k              818k       -2.41%


Remaining CPU time regression, that is,
the change from before CL 214239 to this change:

name        old time/op       new time/op       delta
Template          208ms ± 2%        209ms ± 1%    ~     (p=0.181 n=47+46)
Unicode          82.9ms ± 2%       81.9ms ± 2%  -1.25%  (p=0.000 n=50+48)
GoTypes           709ms ± 3%        714ms ± 3%  +0.77%  (p=0.003 n=48+49)
Compiler          3.31s ± 2%        3.32s ± 2%    ~     (p=0.271 n=48+48)
SSA               10.8s ± 1%        10.9s ± 1%  +0.61%  (p=0.000 n=46+47)
Flate             134ms ± 2%        134ms ± 1%  +0.41%  (p=0.002 n=48+46)
GoParser          166ms ± 2%        167ms ± 2%  +0.41%  (p=0.010 n=46+48)
Reflect           440ms ± 4%        444ms ± 4%  +1.05%  (p=0.002 n=50+49)
Tar               183ms ± 2%        184ms ± 2%    ~     (p=0.074 n=45+45)
XML               247ms ± 2%        248ms ± 2%  +0.67%  (p=0.001 n=49+48)
[Geo mean]        425ms             427ms       +0.34%

name        old user-time/op  new user-time/op  delta
Template          271ms ± 2%        271ms ± 2%    ~     (p=0.654 n=48+48)
Unicode           117ms ± 2%        116ms ± 3%    ~     (p=0.458 n=47+45)
GoTypes           952ms ± 3%        963ms ± 2%  +1.11%  (p=0.000 n=48+49)
Compiler          4.50s ± 5%        4.49s ± 7%    ~     (p=0.894 n=50+50)
SSA               15.0s ± 2%        15.1s ± 2%  +0.46%  (p=0.015 n=50+49)
Flate             166ms ± 2%        167ms ± 2%  +0.40%  (p=0.005 n=49+48)
GoParser          202ms ± 2%        203ms ± 2%  +0.60%  (p=0.002 n=49+47)
Reflect           583ms ± 3%        588ms ± 3%  +0.82%  (p=0.001 n=49+46)
Tar               223ms ± 2%        224ms ± 2%  +0.37%  (p=0.046 n=48+46)
XML               310ms ± 2%        311ms ± 2%  +0.46%  (p=0.009 n=50+49)
[Geo mean]        554ms             556ms       +0.36%


Change-Id: I85951a6538373ef4309a2cc366cc1ebaf1f4582d
Reviewed-on: https://go-review.googlesource.com/c/go/+/214818
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

I noticed this leak while writing CL 214977.

Change-Id: I7566952b8e4bc58939d23435aea86576fc58ddca
Reviewed-on: https://go-review.googlesource.com/c/go/+/214978
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Based on riscv-go port.

Updates #27532

Change-Id: Id8ae7d851c393ec3702e4176c363accb0a42587f
Reviewed-on: https://go-review.googlesource.com/c/go/+/204633Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Go 1.14 will drop support for macOS 10.10, see #23011

This reverts CL 155097

Updates #26475
Updates #29340

Change-Id: I64d0275141407313b73068436ee81d13eacc4c76
Reviewed-on: https://go-review.googlesource.com/c/go/+/214058
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #36520

Change-Id: I698ab235f82f7c81caa09318c954847cf3833153
GitHub-Last-Rev: 368a1dc7889c2370fba272bcb45d94822b60d7b9
GitHub-Pull-Request: golang/go#36559
Reviewed-on: https://go-review.googlesource.com/c/go/+/214821Reviewed-by: Robert Griesemer <gri@golang.org>

Change-Id: I83f806e76ef4d268b187bd273d78ceb41b7e8fa5
GitHub-Last-Rev: ee82eaae64536cecb631df328aafe2541f71d3f2
GitHub-Pull-Request: golang/go#36194
Reviewed-on: https://go-review.googlesource.com/c/go/+/211799Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The HTML linter 'tidy' reports:

	go_spec.html:2556: Warning: unescaped & which should be written as &
	go_spec.html:3293: Warning: unescaped & or unknown entity "&s1"
	go_spec.html:3293: Warning: unescaped & or unknown entity "&a"
	go_spec.html:3294: Warning: unescaped & or unknown entity "&s2"
	go_spec.html:3294: Warning: unescaped & or unknown entity "&a"
	go_spec.html:2045: Warning: trimming empty <p>
	go_spec.html:4526: Warning: trimming empty <ul>
	go_spec.html:4533: Warning: trimming empty <ul>
	go_spec.html:4539: Warning: trimming empty <ul>

This CL fixes all but the <ul> ones, which I think should be fixed
but are defended by a comment.

Change-Id: I0ca88f5e80755024801877ab1298025ecf8f10c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/214457Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

This reduces lock contention when only a few P's are running and
checking for whether they need to run timers on the sleeping P's.
Without this change the running P's would get lock contention
while looking at the sleeping P's timers. With this change a single
atomic load suffices to determine whether there are any ready timers.

Change-Id: Ie843782bd56df49867a01ecf19c47498ec827452
Reviewed-on: https://go-review.googlesource.com/c/go/+/214185
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: David Chase <drchase@google.com>

Currently, the scavenger is paced according to how long it takes to
scavenge one runtime page's worth of memory. However, this pacing
doesn't take into account the additional cost of actually using a
scavenged page. This operation, "sysUsed," is a counterpart to the
scavenging operation "sysUnused." On most systems this operation is a
no-op, but on some systems like Darwin and Windows we actually make a
syscall. Even on systems where it's a no-op, the cost is implicit: a
more expensive page fault when re-using the page.

On Darwin in particular the cost of "sysUnused" is fairly close to the
cost of "sysUsed", which skews the pacing to be too fast. A lot of
soon-to-be-allocated memory ends up scavenged, resulting in many more
expensive "sysUsed" operations, ultimately slowing down the application.

The way to fix this problem is to include the future cost of "sysUsed"
on a page in the scavenging cost. However, measuring the "sysUsed" cost
directly (like we do with "sysUnused") on most systems is infeasible
because we would have to measure the cost of the first access.

Instead, this change applies a multiplicative constant to the measured
scavenging time which is based on a per-system ratio of "sysUnused" to
"sysUsed" costs in the worst case (on systems where it's a no-op, we
measure the cost of the first access). This ultimately slows down the
scavenger to a more reasonable pace, limiting its impact on performance
but still retaining the memory footprint improvements from the previous
release.

Fixes #36507.

Change-Id: I050659cd8cdfa5a32f5cc0b56622716ea0fa5407
Reviewed-on: https://go-review.googlesource.com/c/go/+/214517
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Even though I contributed to golang/go[^1], the rule[^2] did not reflect my name in CONTRIBUTORS, so I added it.

[^1]: https://go-review.googlesource.com/c/go/+/164199
[^2]: https://github.com/golang/build/blob/e21a90b/cmd/updatecontrib/updatecontrib.go#L118

Change-Id: I5d6b5684d61ea5da679519a9e703d977470de175
Reviewed-on: https://go-review.googlesource.com/c/go/+/214617Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This reverts CL 214437.

Does not fix the issue, and the test was wrong so it did not detect that it did not fix the issue.

Updates #36375

Change-Id: I6a4112035a1e90f4fdafed6fdf4ec9dfc718b571
Reviewed-on: https://go-review.googlesource.com/c/go/+/214601Reviewed-by: Ian Lance Taylor <iant@golang.org>

Since Durations only span 290 years, they are not good for
manipulating very remote times. I bounced off this problem recently
while doing some astronomical calculations and it took me a while to
realize I could get a 64-bit seconds value from time.Time.Unix and
subtract two of them to evaluate the interval.

I thought it worth adding a sentence to make this clear. It didn't
occur to me for quite a while that "Unix time" spans a huge range in
the Go library.

Change-Id: I76c75dc951dfd6bcf86e8b0be3cfec518a3ecdee
Reviewed-on: https://go-review.googlesource.com/c/go/+/213977Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

Fixes #36526.

Change-Id: Ic51a287579f139422cc1a7b2fb82d6732114b031
Reviewed-on: https://go-review.googlesource.com/c/go/+/214597Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #36375

Change-Id: I407a1db23868880b83e73bc136d274659483fb69
Reviewed-on: https://go-review.googlesource.com/c/go/+/214437
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change the type printer to take a map of types that we're currently
printing. When we happen upon a type that we're already in the middle
of printing, print a reference to it instead.

A reference to another type is built using the offset of the first
byte of that type's string representation in the result. To facilitate
that computation (and it's probably more efficient, regardless), we
print the type to a buffer as we go, and build the string at the end.

It would be nice to use string.Builder instead of bytes.Buffer, but
string.Builder wasn't around in Go 1.4, and we'd like to bootstrap
from that version.

Fixes #29312

Change-Id: I49d788c1fa20f770df7b2bae3b9979d990d54803
Reviewed-on: https://go-review.googlesource.com/c/go/+/214239Reviewed-by: Robert Griesemer <gri@golang.org>

The comment contained a link that had a file name and ID that no longer existed, so change to the URL of the corresponding part of the latest page.

Change-Id: I74e0885aabf470facc39b84035f7a83fef9c6a8e
GitHub-Last-Rev: 5681c84d9f1029449da6860c65a1d9a128296e85
GitHub-Pull-Request: golang/go#36514
Reviewed-on: https://go-review.googlesource.com/c/go/+/214181
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Whenever more than 1/4 of the timers on a P's heap are deleted,
remove them from the heap.

Change-Id: Iff63ed3d04e6f33ffc5c834f77f645c52c007e52
Reviewed-on: https://go-review.googlesource.com/c/go/+/214299
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

Updates #36489

Change-Id: I1ca215ba0a64a31d662134385b8be46bb4ba4434
Reviewed-on: https://go-review.googlesource.com/c/go/+/214282
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

We had a few test cases to make sure checkptr didn't have certain
false positives, but none to test for any true positives. This CL
fixes that.

Updates #22218.

Change-Id: I24c02e469a4af43b1748829a9df325ce510f7cc4
Reviewed-on: https://go-review.googlesource.com/c/go/+/214238
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Make file names consistent, using only forward slashes in the path.

Fixes #36495

Change-Id: I337119d6dff233ab9d4bfe757147ec25961ae021
Reviewed-on: https://go-review.googlesource.com/c/go/+/214286
Run-TryBot: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This pulls in two new commits: a fix for a test broken on plan9 and a
correction to a comment.

Change-Id: I31cf046a5073872714c758894732b2fcc800ab6b
Reviewed-on: https://go-review.googlesource.com/c/go/+/214289
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

When adjustTimers sees a timerModifiedEarlier or timerModifiedLater,
it removes it from the heap, leaving a new timer at that position
in the heap. We were accidentally skipping that new timer in our loop.
In some unlikely cases this could cause adjustTimers to look at more
timers than necessary.

Change-Id: Ic71e54c175ab7d86a7fa46f1497aca71ed1c43cc
Reviewed-on: https://go-review.googlesource.com/c/go/+/214338
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This imports CL 213880.

Fixes #35511

Change-Id: I55d18713bdac8fa556ba5a2aced922f80d1ac970
Reviewed-on: https://go-review.googlesource.com/c/go/+/214078Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Ic7997d1f747152afec78e8e439770166029f34ec
GitHub-Last-Rev: 6a07f25056c960dc8684cd6eac22cd3405a936c8
GitHub-Pull-Request: golang/go#36491
Reviewed-on: https://go-review.googlesource.com/c/go/+/214298
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Go 1.14 will drop support for macOS 10.10, see #23011

This reverts CL 125304

Updates #26475
Updates #26513

Change-Id: Ia13eef30f22d67103f7ae45424124fbb116e1261
Reviewed-on: https://go-review.googlesource.com/c/go/+/214057
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Go 1.14 will be the last to support macOS 10.11.
Go 1.15 will require macOS 10.12 (Sierra).

Updates #23011

Change-Id: I8fff555e5b8fffe088e7e960e77fac9558cb74e4
Reviewed-on: https://go-review.googlesource.com/c/go/+/210137Reviewed-by: Andrew Bonventre <andybons@golang.org>

Updates #34964.

Change-Id: I5afb2c1e77a9a47358a1d0d108c4a787d7172b94
Reviewed-on: https://go-review.googlesource.com/c/go/+/214217
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

In "Module support" section, there were two mentions of "Go 1.13",
assuming that's the latest version. Rather than update these to 1.14,
this CL changes those to "The go command".

Also, a minor change in wording for finding go.mod files.

Change-Id: Id194be9405b540f221464814e71c361a22cc0f55
Reviewed-on: https://go-review.googlesource.com/c/go/+/214140
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Hopefully we'll have the remaining safety violations in the standard
library ironed out by 1.15.

We also fix a minor (but important) typo while we're here.

Updates #34964, #34972.

Change-Id: Ic72fd4d9411b749f8c0cea87e95ab68347009893
Reviewed-on: https://go-review.googlesource.com/c/go/+/214118Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This update was automatically generated using the updatecontrib command:

	cd gotip
	go run golang.org/x/build/cmd/updatecontrib

With minor manual changes based on publicly available information
to canonicalize letter case and formatting for a few names.

Actions taken (relative to CONTRIBUTORS at origin/master):

	Added Aaron Beitch <aaronb@arista.com>
	Added Adam Shelton <aashelt90@gmail.com>
	Added Aditya Harindar <aditya.harindar@gmail.com>
	Added Alec Benzer <alec.benzer@gmail.com>
	Added Alex Buchanan <buchanae@gmail.com>
	Added Alex Gaynor <alex@alloy.us>
	Added Alex Harford <alex.harford@saucelabs.com>
	Added Alex Zhirov <azhirov@google.com>
	Added Alexandr Mayorskiy <a.mayorskiy@corp.mail.ru>
	Added An Xiao <hac@zju.edu.cn>
	Added Andrei Enshin <b1os@bk.ru>
	Added Andrew Medvedev <andrew.y.medvedev@gmail.com>
	Added Andrew Stormont <astormont@racktopsystems.com>
	Added Antonio Huete Jimenez <tuxillo@quantumachine.net>
	Added Arda Güçlü <ardaguclu@gmail.com>
	Added Artem Alekseev <artem.alekseev@intel.com>
	Added Ayan George <ayan@ayan.net>
	Added Barnaby Keene <accounts@southcla.ws>
	Added Ben Toews <mastahyeti@gmail.com>
	Added Benjamin Wuethrich <benjamin.wuethrich@gmail.com>
	Added Brandon Philips <brandon@ifup.org>
	Added Carlos Amedee <carlos@golang.org>
	Added Changkun Ou <hi@changkun.us>
	Added Chauncy Cullitan <chauncyc@google.com>
	Added Clint J. Edwards <clint.j.edwards@gmail.com>
	Added Daisuke Suzuki <daisuzu@gmail.com>
	Added Dan Scales <danscales@google.com>
	Added David Bond <davidsbond93@gmail.com>
	Added Denis Isaev <idenx@yandex.com>
	Added Domas Tamašauskas <puerdomus@gmail.com>
	Added Duco van Amstel <duco.vanamstel@gmail.com>
	Added Eduardo Villaseñor <evillasrmx@gmail.com>
	Added Eric Biggers <ebiggers@google.com>
	Added Eric Brown <browne@vmware.com>
	Added Eric Rutherford <erutherford@gmail.com>
	Added Gabriel Rosenhouse <rosenhouse@gmail.com>
	Added George Hartzell <hartzell@alerce.com>
	Added Gert Cuykens <gert.cuykens@gmail.com>
	Added Ghazni Nattarshah <ghazni.nattarshah@gmail.com>
	Added GitHub User DQNEO (188741) <dqneoo@gmail.com>
	Added GitHub User Matts966 (28551465) <Matts966@users.noreply.github.com>
	Added GitHub User ajz01 (4744634) <ajzdenek@gmail.com>
	Added GitHub User andig (184815) <cpuidle@gmx.de>
	Added GitHub User jinmiaoluo (39730824) <jinmiaoluo@icloud.com>
	Added GitHub User maltalex (10195391) <code@bit48.net>
	Added GitHub User po3rin (29445112) <abctail30@gmail.com>
	Added GitHub User pokutuna (57545) <popopopopokutuna@gmail.com>
	Added GitHub User ramenjuniti (32011829) <ramenjuniti@gmail.com>
	Added GitHub User skanehira (7888591) <sho19921005@gmail.com>
	Added GitHub User witchard (4994659) <witchard@hotmail.co.uk>
	Added GitHub User zikaeroh (48577114) <zikaeroh@gmail.com>
	Added Günther Noack <gnoack@google.com>
	Added Hasit Bhatt <hasit.p.bhatt@gmail.com>
	Added Howard Zhang <howard.zhang@arm.com>
	Added Huan Du <i@huandu.me>
	Added Ignacio Hagopian <jsign.uy@gmail.com>
	Added Ilya Sinelnikov <sidhmangh@gmail.com>
	Added Irbe Krumina <irbekrm@gmail.com>
	Added Isfan Azhabil <isfan.azhabil@tokopedia.com>
	Added Ivan Trubach <mr.trubach@icloud.com>
	Added Jaap Aarts <jaap.aarts1@gmail.com>
	Added Jeremy Faller <jeremy@golang.org>
	Added Johan Jansson <johan.jansson@iki.fi>
	Added John Papandriopoulos <jpap.code@gmail.com>
	Added Jorge L. Fatta <jorge.fatta@auth0.com>
	Added Josa Gesell <josa@gesell.me>
	Added Julian Tibble <julian.tibble@gmail.com>
	Added Jun Zhang <jim.zoumo@gmail.com>
	Added Jędrzej Szczepaniak <jbszczepaniak@gmail.com>
	Added Kalman Bekesi <kalmanb@google.com>
	Added Katharine Berry <ktbry@google.com>
	Added Keisuke Kishimoto <keisuke.kishimoto@gmail.com>
	Added Kevan Swanberg <kevswanberg@gmail.com>
	Added Koki Tomoshige <tomocy.dev@gmail.com>
	Added Liz Rice <liz@lizrice.com>
	Added Lorenz Brun <lorenz@brun.one>
	Added Luke Young <bored-engineer@users.noreply.github.com>
	Added Marc Sanmiquel <marcsanmiquel@gmail.com>
	Added Marko Kungla <marko.kungla@gmail.com>
	Added Mikhail Fesenko <proggga@gmail.com>
	Added Mohit Verma <vmohit.93@gmail.com>
	Added Moritz Fain <moritz@fain.io>
	Added Nathan Dias <nathan.dias@orijtech.com>
	Added Nikita Vanyasin <nikita.vanyasin@gmail.com>
	Added Nuno Cruces <ncruces@users.noreply.github.com>
	Added Oliver Powell <oliverpowell84@gmail.com>
	Added Panos Georgiadis <pgeorgiadis@suse.de>
	Added Pantelis Sampaziotis <psampaz@gmail.com>
	Added Paulo Gomes <paulo.gomes.uk@gmail.com>
	Added Prashant Agrawal <prashant.a.vjti@gmail.com>
	Added Ricardo Seriani <ricardo.seriani@gmail.com>
	Added Rob Findley <rfindley@google.com>
	Added Robin Zhong <robin@robinzhong.co>
	Added Rohan Challa <rohan@golang.org>
	Added Roman Kollár <roman.kollar.0@gmail.com>
	Added Ruixin Bao <ruixin.bao@ibm.com>
	Added Sardorbek Pulatov <sardorbek.pulatov@outlook.com>
	Added Scott Ragan <ragansa@fb.com>
	Added Sean Liao <seankhliao@gmail.com>
	Added Sebastian Chlopecki <sebsebmc@gmail.com>
	Added Sebastian Kinne <skinne@google.com>
	Added Sergei Lemeshkin <sergeilem@gmail.com>
	Added Serhat Giydiren <serhatgiydiren@gmail.com>
	Added Shivashis Padhi <shivashispadhi@gmail.com>
	Added Simarpreet Singh <simar@linux.com>
	Added Simon Ferquel <simon.ferquel@docker.com>
	Added Simon Rozman <simon@rozman.si>
	Added Sjoerd Siebinga <sjoerd.siebinga@gmail.com>
	Added Spencer Kocot <spencerkocot@gmail.com>
	Added Srinidhi Kaushik <shrinidhi.kaushik@gmail.com>
	Added Sven Taute <sven.taute@gmail.com>
	Added Tao Qingyun <qingyunha@gmail.com>
	Added Tianji Wu <the729@gmail.com>
	Added Tomas Dabasinskas <tomas@dabasinskas.net>
	Added Ville Skyttä <ville.skytta@iki.fi>
	Added Vitaly Zdanevich <zdanevich.vitaly@ya.ru>
	Added Vladimir Evgrafov <evgrafov.vladimir@gmail.com>
	Added Vojtech Bocek <vbocek@gmail.com>
	Added Wang Xuerui <git@xen0n.name>
	Added William Poussier <william.poussier@gmail.com>
	Added Xiangdong Ji <xiangdong.ji@arm.com>
	Added Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
	Added Ziheng Liu <lzhfromustc@gmail.com>
	Used GitHub User DQNEO (188741) form for DQNEO <dqneoo@gmail.com> https://github.com/golang/go/commit/f07059d949 [go]
	Used GitHub User Matts966 (28551465) form for Matts966 <Matts966@users.noreply.github.com> https://github.com/golang/tools/commit/d89860af [tools]
	Used GitHub User ajz01 (4744634) form for ajz01 <ajzdenek@gmail.com> https://github.com/golang/go/commit/57ad6ef15d [go]
	Used GitHub User andig (184815) form for andig <cpuidle@gmx.de> https://github.com/golang/go/commit/cf630586ca [go sys]
	Used GitHub User jinmiaoluo (39730824) form for jinmiaoluo <jinmiaoluo@icloud.com> https://github.com/golang/go/commit/c7e73ef60a [go]
	Used GitHub User maltalex (10195391) form for maltalex <code@bit48.net> https://github.com/golang/sys/commit/c709ea0 [sys]
	Used GitHub User po3rin (29445112) form for po3rin <abctail30@gmail.com> https://github.com/golang/go/commit/bf865823ba [go]
	Used GitHub User pokutuna (57545) form for pokutuna <popopopopokutuna@gmail.com> https://github.com/golang/go/commit/46e0d724b3 [go]
	Used GitHub User ramenjuniti (32011829) form for ramenjuniti <ramenjuniti@gmail.com> https://github.com/golang/go/commit/f9dd99cae3 [go]
	Used GitHub User skanehira (7888591) form for skanehira <sho19921005@gmail.com> https://github.com/golang/go/commit/87805c92fd [go]
	Used GitHub User utkarsh-extc (53217283) form for utkarsh-extc <53217283+utkarsh-extc@users.noreply.github.com> https://github.com/golang/sys/commit/51ab0e2 [sys]
	Used GitHub User witchard (4994659) form for witchard <witchard@hotmail.co.uk> https://github.com/golang/go/commit/42db1da8e9 [go]
	Used GitHub User zikaeroh (48577114) form for zikaeroh <zikaeroh@gmail.com> https://github.com/golang/tools/commit/e84277c2 [tools]
	Used GitHub name "Adam Shelton" for Adam <aashelt90@gmail.com> https://github.com/golang/exp/commit/c286b88 [exp]
	Used GitHub name "Andrew Bonventre" for Andrew <andybons@golang.org> https://github.com/golang/go/commit/8bbfc51d9a [arch blog build crypto debug exp gddo go image lint mobile net oauth2 perf playground proposal.git review sync sys talks term text time tools tour website]
	Used GitHub name "David Bond" for davidsbond <davidsbond93@gmail.com> https://github.com/golang/go/commit/b421b85841 [go]
	Used GitHub name "Eduardo Villaseñor" for galaxy-designer <evillasrmx@gmail.com> https://github.com/golang/tools/commit/db047d72 [tools]
	Used GitHub name "George Hartzell" for hartzell <hartzell@alerce.com> https://github.com/golang/tools/commit/5eefd052 [tools]
	Used GitHub name "Ignacio Hagopian" for jsign <jsign.uy@gmail.com> https://github.com/golang/go/commit/4d4ddd862d [go]
	Used GitHub name "Ivan Markin" for nogoegst <nogoegst@users.noreply.github.com> https://github.com/golang/go/commit/a1addf15df [go]
	Used GitHub name "Jun Zhang" for zoumo <jim.zoumo@gmail.com> https://github.com/golang/tools/commit/81ca6dc7 [tools]
	Used GitHub name "Keiji Yoshida" for yosssi <yoshida.keiji.84@gmail.com> https://github.com/golang/lint/commit/ac6833c [lint]
	Used GitHub name "Koki Tomoshige" for tomocy <tomocy.dev@gmail.com> https://github.com/golang/go/commit/2f04903fec [go]
	Used GitHub name "Michalis Kargakis" for kargakis <mkargaki@redhat.com> https://github.com/golang/go/commit/e243d242d7 [go]
	Used GitHub name "Nikita Vanyasin" for nikita-vanyasin <nikita.vanyasin@gmail.com> https://github.com/golang/go/commit/c3e8a20a65 [go]
	Used GitHub name "Roberto Clapis" for Roberto <empijei@users.noreply.github.com> https://github.com/golang/go/commit/963776e689 [go]
	Used GitHub name "Robin Eklind" for mewmew <rnd0x00@gmail.com> https://github.com/golang/go/commit/b8620afb8d [arch blog go proposal.git]
	Used GitHub name "Sergei Lemeshkin" for sergeilem <sergeilem@gmail.com> https://github.com/golang/go/commit/a3a1bdff79 [go]
	Used GitHub name "Vladimir Evgrafov" for vovapi <evgrafov.vladimir@gmail.com> https://github.com/golang/go/commit/207a0b7933 [go]

Updates #12042

Change-Id: I1ba3c17108491316255f914c3a71f69fc6f4341a
Reviewed-on: https://go-review.googlesource.com/c/go/+/213824Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>

Currently, scavenging information is printed if the gctrace debug
variable is >0. Scavenging information is also printed naively, for
every page scavenged, resulting in a lot of noise when the typical
expectation for GC trace is one line per GC.

This change adds a new GODEBUG flag called scavtrace which prints
scavenge information roughly once per GC cycle and removes any scavenge
information from gctrace. The exception is debug.FreeOSMemory, which may
force an additional line to be printed.

Fixes #32952.

Change-Id: I4177dcb85fe3f9653fd74297ea93c97c389c1811
Reviewed-on: https://go-review.googlesource.com/c/go/+/212640
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The information requested by these flags is not available from the
vendor directory.

Noticed while diagnosing #36478.

Updates #33848

Change-Id: I2b181ba5c27f01fdd6277d8d0ab1003c05774ff7
Reviewed-on: https://go-review.googlesource.com/c/go/+/214081
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

'go list -m' allows explicit module@version arguments,
which it resolves (using Query) but does not add to the build list.
Similarly, 'go list -u' resolves versions without modifying the build list.

These explicit operations should be allowed even when '-mod=readonly' is set.

Updates #36478

'go list' and 'go mod download' do not

Change-Id: I5d2735729ad573635b9c1902d5d3a8bd960b8a76
Reviewed-on: https://go-review.googlesource.com/c/go/+/214077
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

On Windows, we implement asynchronous preemption using SuspendThread
to suspend other threads in our process. However, SuspendThread is
itself actually asynchronous (it enqueues a kernel "asynchronous
procedure call" and returns). Unfortunately, Windows' ExitProcess API
kills all threads except the calling one and then runs APCs. As a
result, if SuspendThread and ExitProcess are called simultaneously,
the exiting thread can be suspended and the suspending thread can be
exited, leaving behind a ghost process consisting of a single thread
that's suspended.

We've already protected against the runtime's own calls to
ExitProcess, but if Go code calls external code, there's nothing
stopping that code from calling ExitProcess. For example, in #35775,
our own call to racefini leads to C code calling ExitProcess and
occasionally causing a deadlock.

This CL fixes this by introducing synchronization between calling
external code on Windows and preemption. It adds an atomic field to
the M that participates in a simple CAS-based synchronization protocol
to prevent suspending a thread running external code. We use this to
protect cgocall (which is used for both cgo calls and system calls on
Windows) and racefini.

Tested by running the flag package's TestParse test compiled in race
mode in a loop. Before this change, this would reliably deadlock after
a few minutes.

Fixes #35775.
Updates #10958, #24543.

Change-Id: I50d847abcdc2688b4f71eee6a75eca0f2fee892c
Reviewed-on: https://go-review.googlesource.com/c/go/+/213837
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>

In CL 204777, I made the "finding" messages in cachingRepo only print
after a “longish” delay, on the theory that they would help diagnose
slow or stuck fetches.

However, as I've been testing Go 1.14 beta 1, I've found that these
messages are mostly just noise, and the fact that they are so
nondeterministic causes both confusion and test flakes (#35539).

Moreover, it currently triggers once for each candidate module, when
what we're usually after is actually a specific package within the
module.

So let's log the package operation unconditionally instead of the
module fetches nondeterministically.

Fixes #35539
Updates #26152

Change-Id: I41a1c772465b2f0b357d3402bc372b6907773741
Reviewed-on: https://go-review.googlesource.com/c/go/+/213679
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

On Windows, it might be possible that SuspendThread suspends a
thread right between when an exception happens and when the
exception handler runs. (This is my guess. I don't know the
implementation detail of Windows exceptions to be sure.) In this
case, we may inject a call to asyncPreempt before the exception
handler runs. The exception handler will inject a sigpanic call,
which will make the stack trace looks like

sigpanic
asyncPreempt
actual panicking function

i.e. it appears asyncPreempt panicked.

Instead, just overwrite the PC, without pushing another frame.

Fixes #35773.

Change-Id: Ief4e964dcb7f45670b5f93c4dcf285cc1c737514
Reviewed-on: https://go-review.googlesource.com/c/go/+/213879
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

We know of at least one module (github.com/stripe/stripe-go) that has
a run of +incompatible versions, followed by a run of versions with
go.mod files, followed by another run of +incompatible versions.

We want the heuristics for showing +incompatible versions to reflect
the authors' current intent, and it seems clear that the current
intent of the authors of that module is for users of the unversioned
import path to still be on +incompatible versions.

To respect that intent, we need to keep checking for +incompatible
versions even after we have seen a lower major version with an
explicit go.mod file.

However, we still don't want to download every single version of the
module to check it. A given major version should have a consistent,
canonical import path, so the path (as inferred by the presence or
absence of a go.mod file) should be the same for every release across
that major version.

To avoid unnecessary overhead — and to allow module authors to correct
accidental changes to a major version's import path — we check only
the most recent release of each major version. If a release
accidentally changes the import path in either direction (by deleting
or adding a go.mod file), it can be corrected by issuing a single
subsequent release of that major version to restore the correct path.

I manually verified that, with this change,
github.com/stripe/stripe-go@latest reverts to v68.7.0+incompatible
as it was in Go 1.13.
The other regression tests for #34165 continue to pass.

Updates #34165

Change-Id: I5daff3cd2123f94c7c49519babf4eecd509f169e
Reviewed-on: https://go-review.googlesource.com/c/go/+/212317Reviewed-by: Jay Conrod <jayconrod@google.com>

This avoids the security problem in #29312 where two very deep, but
distinct, types are given the same name. They both make it to the
linker which chooses one, and the use of the other is now type unsafe.

Instead, give every very deep type its own name. This errs on the
other side, in that very deep types that should be convertible to each
other might now not be. But at least that's not a security hole.

Update #29312.

Change-Id: Iac0ebe73fdc50594fd6fbf7432eef65f9a053126
Reviewed-on: https://go-review.googlesource.com/c/go/+/213517
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>

Fixes #35620

Change-Id: I71bc56ec7a7507d14b4f013177b4b816bb1a2094
Reviewed-on: https://go-review.googlesource.com/c/go/+/212458Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This is more readable and less error-prone than using RSP offsets.

Suggested during review of CL 212765.

Change-Id: I070190abeeac8eae5dbd414407602619d9d57422
Reviewed-on: https://go-review.googlesource.com/c/go/+/213577
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>