This makes it possible to avoid tests where coverage affects the test
results by skipping them (or otherwise adjusting them) when coverage
is enabled.

Update #17699

Change-Id: Ifcc36cfcd88ebd677890e82ba80ee3d696ed3d7c
Reviewed-on: https://go-review.googlesource.com/32483Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #13290

Change-Id: I0f7e7683d86db501cbedb6a0b7349ceb0769701c
Reviewed-on: https://go-review.googlesource.com/32481Reviewed-by: Martin Möhrmann <martisch@uos.de>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

sigfwd calls an arbitrary C signal handler function.  The System V ABI
for x86_64 (and the most recent revision of the ABI for i386) requires
the stack to be 16-byte aligned.

Fixes: #17641

Change-Id: I77f53d4a8c29c1b0fe8cfbcc8d5381c4e6f75a6b
Reviewed-on: https://go-review.googlesource.com/32107
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Go's http1 implementation originally had a mechanism to send HTTP
trailers based on pre-declaring the trailer keys whose values you'd
later let after the header was written.

http2 copied the same mechanism, but it was found to be unsufficient
for gRPC's wire protocol. A second trailer mechanism was added later
(but only to http2) for handlers that want to send a trailer without
knowing in advance they'd need to.

Copy the same mechanism back to http1 and document it.

Fixes #15754

Change-Id: I8c40d55e28b0e5b7087d3d1a904a392c56ee1f9b
Reviewed-on: https://go-review.googlesource.com/32479Reviewed-by: Ian Lance Taylor <iant@golang.org>

Skip TestObjdumpPowerManual if the host system is not ppc64 or ppc64le.
This test depends on using the host objdump and comparing output, which
does not work as expected if the test is run on another host.

Orignates from golang.org/x/arch/ppc64/ppc64asm commit 8e2d4898.

Fixes #17698

Change-Id: I956b0fb78c5ec33641db752d46a755008403d269
Reviewed-on: https://go-review.googlesource.com/32531Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This should never be called but should help identify causes of
unexpected panics such as in issue #17716.

Change-Id: Id6ad0cef1088a41bfcc69110a93484a7e39c4128
Reviewed-on: https://go-review.googlesource.com/32480
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

Fixes #17683

Change-Id: I46f45c63796b58e8a8f14e37592231cbe7cd6934
Reviewed-on: https://go-review.googlesource.com/32438Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The introduction of -buildmode=plugin means modules can be added to a
Go program while it is running. This means there exists some time
while the program is running with the module is on the moduledata
linked list, but it has not been initialized to the satisfaction of
other parts of the runtime. Notably, the GC.

This CL adds a new way of access modules, an activeModules function.
It returns a slice of modules that is built in the background and
atomically swapped in. The parts of the runtime that need to wait on
module initialization can use this slice instead of the linked list.

Fixes #17455

Change-Id: I04790fd07e40c7295beb47cea202eb439206d33d
Reviewed-on: https://go-review.googlesource.com/32357Reviewed-by: Ian Lance Taylor <iant@golang.org>

There is no benefit to folding ADDconsts unless the resultant immediate
will fit into a 20-bit signed integer, so limit these rules accordingly.

Also the signed load operations were missing, so I've added them, and
I've also removed some MOVDaddr rules that were dead code (MOVDaddrs
are rematerializable on s390x which means they can't take inputs other
than SP or SB).

Change-Id: Iebeba78da37d3d71d32d4b7f49fe4ea9095d40ec
Reviewed-on: https://go-review.googlesource.com/30616
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

- Adds overflow checks
- Adds parsing of negative integers
- Adds boolean return value to signal parsing errors
- Adds atoi32 for parsing of integers that fit in an int32
- Adds tests

Handling of errors to provide error messages
at the call sites is left to future CLs.

Updates #17718

Change-Id: I3cacd0ab1230b9efc5404c68edae7304d39bcbc0
Reviewed-on: https://go-review.googlesource.com/32390Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This implements a check that can be done at runtime for the ISA level and
hardware capability. It follows the same implementation as in s390x.

These checks will be important as we enable new instructions and write go
asm implementations using those.

Updates #15403
Fixes #16643

Change-Id: Idfee374a3ffd7cf13a7d8cf0a6c83d247d3bee16
Reviewed-on: https://go-review.googlesource.com/32330Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Use vector instructions to speed up indexing operations for short
strings (64 bytes or less).

bytes_s390x.go and strings_s390x.go are based on their amd64
equivalents in CL 31690.

bytes package:

name                   old time/op    new time/op    delta
Index/10                 40.3ns ± 7%    11.3ns ± 4%    -72.06%  (p=0.000 n=10+10)
Index/32                  196ns ± 1%      27ns ± 2%    -86.25%  (p=0.000 n=10+10)
Index/4K                 28.9µs ± 1%     1.5µs ± 2%    -94.94%    (p=0.000 n=9+9)
Index/4M                 30.1ms ± 2%     1.5ms ± 3%    -94.94%  (p=0.000 n=10+10)
Index/64M                 549ms ±13%      28ms ± 3%    -94.87%   (p=0.000 n=10+9)
IndexEasy/10             18.8ns ±11%    11.5ns ± 2%    -38.81%  (p=0.000 n=10+10)
IndexEasy/32             23.6ns ± 6%    28.1ns ± 3%    +19.29%  (p=0.000 n=10+10)
IndexEasy/4K              251ns ± 5%     223ns ± 8%    -11.04%  (p=0.000 n=10+10)
IndexEasy/4M              318µs ± 9%     266µs ± 8%    -16.42%  (p=0.000 n=10+10)
IndexEasy/64M            14.7ms ±16%    13.2ms ±11%    -10.22%  (p=0.001 n=10+10)

strings package:

name                   old time/op  new time/op  delta
IndexRune              88.1ns ±16%  28.9ns ± 4%  -67.20%  (p=0.000 n=10+10)
IndexRuneLongString     456ns ± 7%    34ns ± 3%  -92.50%  (p=0.000 n=10+10)
IndexRuneFastPath      12.9ns ±14%  11.1ns ± 6%  -13.84%  (p=0.000 n=10+10)
Index                  13.0ns ± 7%  11.3ns ± 4%  -13.31%  (p=0.000 n=10+10)
IndexHard1             3.38ms ± 9%  0.07ms ± 1%  -97.79%  (p=0.000 n=10+10)
IndexHard2             3.58ms ± 7%  0.37ms ± 2%  -89.78%  (p=0.000 n=10+10)
IndexHard3             3.47ms ± 7%  0.75ms ± 1%  -78.52%  (p=0.000 n=10+10)
IndexHard4             3.56ms ± 6%  1.34ms ± 0%  -62.39%    (p=0.000 n=9+9)

Change-Id: If36c2afb8c02e80fcaa1cf5ec2abb0a2be08c7d1
Reviewed-on: https://go-review.googlesource.com/32447
Run-TryBot: Michael Munday <munday@ca.ibm.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

In a previous change, cmd/go was taught to show a "no tests ran" warning
if test did nothing. But it missed a case - if no tests nor examples ran
but any benchmarks were meant to be run, it would still produce the
warning. This meant that running only benchmarks, which is common, would
be confusing:

	 $ go test -run='^$' -bench=.
	testing: warning: no tests to run
	BenchmarkFoo-4            300000              5056 ns/op
	[...]

I believe this was because of a copy-paste error in the tests. This was
being tested, but on the wrong file which does contain a test that was
being run. Fix the path and fix the now failing test by never showing
the warning if -bench was given a non-empty string.

The rationale is that if -bench was given but there was no output, it's
obvious that nothing happened as benchmarks always produce output even
without -v. So showing a warning in those cases is redundant.

To make future typos less likely, make sure that no tests are being run
in the cases where we only want to run benchmarks.

Fixes #17603.

Change-Id: I4c626caf39f72260c6a9761c06446663f465f947
Reviewed-on: https://go-review.googlesource.com/32157Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Adds ModifyResponse, an optional func to ReverseProxy
that modifies a response in the backend, right before
the headers of the response are written to the internal
response writer.
If ModifyResponse returns an error, the proxy returns
a StatusBadGateway error.

Fixes #14237.

Change-Id: I8e03139e34dea0084512ccbd8cc49e941bf9fb5d
Reviewed-on: https://go-review.googlesource.com/32356Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This CL expands upon a change made in (http://golang.org/cl/21811)
to ensure that a nil RawMessage gets serialized as "null" instead of
being a nil slice.

The added check only triggers when the RawMessage is nil. We do not
handle the case when the RawMessage is non-nil, but empty.

Fixes #17704
Updates #14493

Change-Id: I0fbebcdd81f7466c5b78c94953afc897f162ceb4
Reviewed-on: https://go-review.googlesource.com/32472Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

If no error handler is provided, terminate parsing with first error
and report that error.

Fixes #17697.

Change-Id: I9070faf7239bd53725de141507912b92ded3474b
Reviewed-on: https://go-review.googlesource.com/32456
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Also updates x/net/http2 to git rev 541150 for:

   http2: add support for graceful shutdown of Server
   https://golang.org/cl/32412

   http2: make http2.Server access http1's Server via an interface check
   https://golang.org/cl/32417

Fixes #4674
Fixes #9478

Change-Id: I8021a18dee0ef2fe3946ac1776d2b10d3d429052
Reviewed-on: https://go-review.googlesource.com/32329
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I54f8788a4703283b9aa3904e2e610097ac3e3586
Reviewed-on: https://go-review.googlesource.com/32471
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>

Currently we have write barriers for direct channel sends, where the
receiver is blocked and the sender is writing directly to the
receiver's stack; but not for direct channel receives, where the
sender is blocked and the receiver is reading directly from the
sender's stack.

This was okay with the old write barrier because either 1) the
receiver would write the received pointer into the heap (causing it to
be shaded), 2) the pointer would still be on the receiver's stack at
mark termination and we would rescan it, or 3) the receiver dropped
the pointer so it wasn't necessarily reachable anyway.

This is not okay with the write barrier because it lets a grey stack
send a white pointer to a black stack and then remove it from its own
stack. If the grey stack was the sole grey-protector of this pointer,
this hides the object from the garbage collector.

Fix this by making direct receives perform a stack-to-stack write
barrier just like direct sends do.

Fixes #17694.

Change-Id: I1a4cb904e4138d2ac22f96a3e986635534a5ae41
Reviewed-on: https://go-review.googlesource.com/32450Reviewed-by: Rick Hudson <rlh@golang.org>

typecheckcomplit nils out node's type, upon finding new errors.
This hides new errors in children's node as well as the type info
of current node. This change fixes that.

Fixes #17645.

Change-Id: Ib473291f31c7e8fa0307cb1d494e0c112ddd3583
Reviewed-on: https://go-review.googlesource.com/32324Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Currently, assists can only perform heap marking jobs. However, at the
beginning of GC, there are only root jobs and no heap marking jobs. As
a result, there's often a period at the beginning of a GC cycle where
no goroutine has accumulated assist credit, but at the same time it
can't get any credit because there are no heap marking jobs for it to
do yet. As a result, many goroutines often block on the assist queue
at the very beginning of the GC cycle.

This commit fixes this by allowing assists to perform root marking
jobs. The tricky part of this (and the reason we haven't done this
before) is that stack scanning jobs can lead to deadlocks if the
goroutines performing the stack scanning are themselves
non-preemptible, since two non-preemptible goroutines may try to scan
each other. To address this, we use the same insight d6625caf used to
simplify the mark worker stack scanning: as long as we're careful with
the stacks and only drain jobs while on the system stack, we can put
the goroutine into a preemptible state while we drain jobs. This means
an assist's user stack can be scanned while it continues to do work.

This reduces the rate of assist blocking in the x/benchmarks HTTP
benchmark by a factor of 3 and all remaining blocking happens towards
the *end* of the GC cycle, when there may genuinely not be enough work
to go around.

Ideally, assists would get credit for working on root jobs. Currently
they do not; however, this change prioritizes heap work over root jobs
in assists, so they're likely to mostly perform heap work. In contrast
with mark workers, for assists, the root jobs act only as a backstop
to create heap work when there isn't enough heap work.

Fixes #15361.

Change-Id: If6e169863e4ad75710b0c8dc00f6125b41e9a595
Reviewed-on: https://go-review.googlesource.com/32432Reviewed-by: Rick Hudson <rlh@golang.org>

This lifts the part of gcAssistAlloc that runs on the system stack to
its own function in preparation for letting assists perform root jobs
(notably stack scanning). This makes it easy to see that there are no
references to the user stack once we've entered gcAssistAlloc1, which
means it's safe to shrink the stack while in gcAssistAlloc1.

This does not yet make assists perform root jobs, so it's not actually
possible for the stack to shrink yet. That will happen in the next
commit.

The code in gcAssistAlloc1 is identical to the code that's currently
passed in a closure to systemstack with one exception. Currently, we
set the "completed" variable in the enclosing scope to indicate that
the assist completed the mark phase. This is exactly the sort of
cross-stack reference lifting this function is meant to prevent. We
replace this variable with setting gp.param to nil or non-nil to
indicate the completion status.

Updates #15361.

Change-Id: Iba7cfb758c781070a441aea86c0117b399a24dbd
Reviewed-on: https://go-review.googlesource.com/32431
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>

Change-Id: I113ea712838511ee823375d9ea059089195414f5
Reviewed-on: https://go-review.googlesource.com/32449
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

Fixes #16910.

Change-Id: I0e97e88bee0361cd3621cacd1d4b84e6e42af718
Reviewed-on: https://go-review.googlesource.com/32424Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Iba5cfa033483b843dbd3681ffad50b117cced4a7
Reviewed-on: https://go-review.googlesource.com/32448Reviewed-by: Alan Donovan <adonovan@google.com>

Previously, on encountering Func.Nname.Type == nil, typecheckfunc()
returned without initializing Decldepth for that func. This causes
typecheckclosure() to fatal. This change ensures that we initialize
Decldepth in all cases.

Fixes #17588.

Change-Id: I2e3c81ad52e8383395025388989e8dbf03438b68
Reviewed-on: https://go-review.googlesource.com/32415Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

We used to have to keep on-stack copies of these types.
Now they can be registerized.

[0]T is kind of trivial but might as well handle it.

This change enables another change I'm working on to improve how x.(T)
expressions are handled (#17405).  This CL helps because now all
types that are direct interface types are registerizeable (e.g. [1]*byte).

No higher-degree arrays for now because non-constant indexes are hard.

Update #17405

Change-Id: I2399940965d17b3969ae66f6fe447a8cefdd6edd
Reviewed-on: https://go-review.googlesource.com/32416
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

This is an extension of
https://go-review.googlesource.com/c/31662/
to mark all the temporaries, not just the ssa-generated ones.

Before-and-after ls -l `go tool -n compile` shows a 3%
reduction in size (or rather, a prior 3% inflation for
failing to filter temps out properly.)

Replaced name-dependent "is it a temp?" tests with calls to
*Node.IsAutoTmp(), which depends on AutoTemp.  Also replace
calls to istemp(n) with n.IsAutoTmp(), to reduce duplication
and clean up function name space.  Generated temporaries
now come with a "." prefix to avoid (apparently harmless)
clashes with legal Go variable names.

Fixes #17644.
Fixes #17240.

Change-Id: If1417f29c79a7275d7303ddf859b51472890fd43
Reviewed-on: https://go-review.googlesource.com/32255
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Change-Id: I8a28a88a655d9929f8641f71573dc01dc53be00f
Reviewed-on: https://go-review.googlesource.com/32443Reviewed-by: Alan Donovan <adonovan@google.com>

This picks up just a trivial fix,
making vet (and thus me) happy.

Change-Id: Ib82ae44c081ff1ec5c078196a6cd5e1a3505d03b
Reviewed-on: https://go-review.googlesource.com/32427
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Ic66eb2939d83559610e62cbb181a8faa6193ecc4
Reviewed-on: https://go-review.googlesource.com/32426
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Makes vet happy.

Change-Id: I00de44a844afa57901b31991acf9e7ac834a9572
Reviewed-on: https://go-review.googlesource.com/32425
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #17592.

Change-Id: I914fa8c0729012990878b6e5c3e99b0f9b0e2be8
Reviewed-on: https://go-review.googlesource.com/32350
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

-M, -P, and -R were for debugging backend passes that no longer
exists.

-g is used for debugging instructions generated with Gins, but the SSA
backend mostly generates instructions directly. The handful of
instructions still generated with Gins are pretty useless for
debugging.

-x was used to debug the old lexer, but now it only causes us to print
file names as they're parsed, and only if we manually hack the
compiler to enable tracing.

Change-Id: Ia58d4bc9c1312693466171a3fcefc1221e9a2381
Reviewed-on: https://go-review.googlesource.com/32428
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Adds an assembly implementation of sha256.block for ppc64le to improve its
performance.  This implementation is largely based on the original amd64
implementation, which unrolls the 64 iterations of the inner loop.

Fixes #17652

benchmark               old ns/op     new ns/op     delta
BenchmarkHash8Bytes     1263          767           -39.27%
BenchmarkHash1K         14048         7766          -44.72%
BenchmarkHash8K         102245        55626         -45.60%

benchmark               old MB/s     new MB/s     speedup
BenchmarkHash8Bytes     6.33         10.43        1.65x
BenchmarkHash1K         72.89        131.85       1.81x
BenchmarkHash8K         80.12        147.27       1.84x

Change-Id: Ib4adf429423b20495580400be10bd7e171bcc70b
Reviewed-on: https://go-review.googlesource.com/32318Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Adds an assembly implementation of sha512.block for ppc64le to improve its
performance.  This implementation is largely based on the original amd64
implementation, unrolling the 80 iterations of the inner loop.

Fixes #17660

benchmark               old ns/op     new ns/op     delta
BenchmarkHash8Bytes     1715          1133          -33.94%
BenchmarkHash1K         10098         5513          -45.41%
BenchmarkHash8K         68004         35278         -48.12%

benchmark               old MB/s     new MB/s     speedup
BenchmarkHash8Bytes     4.66         7.06         1.52x
BenchmarkHash1K         101.40       185.72       1.83x
BenchmarkHash8K         120.46       232.21       1.93x

Change-Id: Ifd55a49a24cb159b3a09a8e928c3f37727aca103
Reviewed-on: https://go-review.googlesource.com/32320Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

These were accidentally removed by a rollback cl: golang.org/cl/32441

Change-Id: I0cfa8b3397be324dabfb8f33b6548a03c10571eb
Reviewed-on: https://go-review.googlesource.com/32334Reviewed-by: Alan Donovan <adonovan@google.com>

This reverts commit b33030a7.

Reason for revert: We're going to try to get the code in this change
submitted in smaller, more carefully reviewed changes.

Change-Id: I4175f4b297f0e69fb78b11f9dc0bd82f27865be7
Reviewed-on: https://go-review.googlesource.com/32441Reviewed-by: Russ Cox <rsc@golang.org>

Fixes #16997

Change-Id: I9ca27d8cff1905584862997d0e8a11ce3c4c21cb
Reviewed-on: https://go-review.googlesource.com/30750Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Also add a link to more information about isolation levels as defined by the
SQL standard. Fixes #17682.

Change-Id: I94c53b713f4c882af40cf15fe5f1e5dbc53ea741
Reviewed-on: https://go-review.googlesource.com/32418Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>