This reverts commit 08f19bbd.

Reason for revert:
The changed transformation takes effect on a larger set
of code snippets than expected.

For example, this:
    func foo() {

        // Comment
        bar()

    }
becomes:
    func foo() {
        // Comment
        bar()

    }

This is an unintended consequence.

Change-Id: Ifca88d6267dab8a8170791f7205124712bf8ace8
Reviewed-on: https://go-review.googlesource.com/81335Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Joe Tsai <joetsai@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #6007

Change-Id: I239a1699122e086e907ac1f18b1c86a650e1438a
Reviewed-on: https://go-review.googlesource.com/81135
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

GOEXPERIMENT is only set during make.bash, so checking the environment
variable isn't effectual. Instead, check the values exposed by objabi.

These experiments look potentially safe, but it seems too late in the
release cycle to try to assuage that. The one exception is frame
pointer experiment, which is trivially safe: it just amounts to
incrementing some stack offsets by PtrSize.

Fixes #22223.

Change-Id: I46dc7c54b1347143d02d6b9635038230cda6d164
Reviewed-on: https://go-review.googlesource.com/80760Reviewed-by: Russ Cox <rsc@golang.org>

It's not safe (it crashes), and it's also useless: if you run
multiple benchmarks in parallel you will not get reliable
timing results from any of them.

Fixes #18603.

Change-Id: I00e5a72f7c98151543cf7d5573c38383276e391a
Reviewed-on: https://go-review.googlesource.com/80841Reviewed-by: Ian Lance Taylor <iant@golang.org>

Reading the mem stats before our own allocations
avoids cluttering memory stats with our recent garbage.

Fixes #20565.

Change-Id: I3b0046c8300dca83cea24013ffebc32b2ae7f742
Reviewed-on: https://go-review.googlesource.com/80739Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Lock in fix for #22738, submitted in CL 78031.

Fixes #22738.

Change-Id: I6896feb158569e3f12fa7055387cbd7caad29ef4
Reviewed-on: https://go-review.googlesource.com/80635
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

The build tags already prevent the tests from being run on windows or
plan9, so there is no need to check GOOS again.

Change-Id: I74d3c3b7756d9c50f6e5fd4c3e8b0db618fdebbb
Reviewed-on: https://go-review.googlesource.com/81295
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Otherwise we may delay the delivery of these signals for an arbitrary
length of time. We are already careful to not block signals that the
program has asked to see.

Also make sure that we don't miss a signal delivery if a thread
decides to stop for a while while executing the signal handler.

Also clean up the TestAtomicStop output a little bit.

Fixes #21433

Change-Id: Ic0c1a4eaf7eba80d1abc1e9537570bf4687c2434
Reviewed-on: https://go-review.googlesource.com/79581
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Change-Id: I850d961e0444f8d34284e994aee183afba35eaa7
Reviewed-on: https://go-review.googlesource.com/79597Reviewed-by: Ian Lance Taylor <iant@golang.org>

This is inspired by
https://blog.cloudflare.com/go-dont-collect-my-garbage/
This CL adds allocation tracking and parallelizes p256-related benchmarks.
Amount of allocations can be significantly reduced by marking amd64 asm
functions as noescape. This exposes a bug in p256MovCond:
PANDN with memory argument will fault if memory is not aligned, so they
are replaced with MOVDQU (which is ok with unaligned memory) and
register version of PANDN.

Results on 88-thread machine (2x 22 cores) below:
crypto/elliptic:
name               old time/op    new time/op    delta
BaseMultP256-88      1.50µs ±11%    1.19µs ± 5%  -20.20%  (p=0.000 n=10+10)
ScalarMultP256-88    5.47µs ± 5%    3.63µs ±10%  -33.66%  (p=0.000 n=9+10)

name               old alloc/op   new alloc/op   delta
BaseMultP256-88        800B ± 0%      288B ± 0%  -64.00%  (p=0.000 n=10+10)
ScalarMultP256-88    2.59kB ± 0%    0.26kB ± 0%  -90.12%  (p=0.000 n=10+10)

name               old allocs/op  new allocs/op  delta
BaseMultP256-88        13.0 ± 0%       6.0 ± 0%  -53.85%  (p=0.000 n=10+10)
ScalarMultP256-88      16.0 ± 0%       5.0 ± 0%  -68.75%  (p=0.000 n=10+10)

crypto/ecdsa:
name              old time/op    new time/op    delta
SignP256-88         8.63µs ±37%    7.55µs ±38%     ~     (p=0.393 n=10+10)
VerifyP256-88       13.9µs ± 8%     7.0µs ± 7%  -49.29%  (p=0.000 n=10+9)
KeyGeneration-88    2.77µs ±11%    2.34µs ±11%  -15.57%  (p=0.000 n=10+10)

name              old alloc/op   new alloc/op   delta
SignP256-88         4.14kB ± 1%    2.98kB ± 2%  -27.94%  (p=0.000 n=10+10)
VerifyP256-88       4.47kB ± 0%    0.99kB ± 0%  -77.84%  (p=0.000 n=9+10)
KeyGeneration-88    1.21kB ± 0%    0.69kB ± 0%  -42.78%  (p=0.000 n=10+10)

name              old allocs/op  new allocs/op  delta
SignP256-88           47.0 ± 0%      34.0 ± 0%  -27.66%  (p=0.000 n=10+10)
VerifyP256-88         38.0 ± 0%      17.0 ± 0%  -55.26%  (p=0.000 n=10+10)
KeyGeneration-88      20.0 ± 0%      13.0 ± 0%  -35.00%  (p=0.000 n=10+10)

On machine with only 4 cores, results are much less impressive:
around 2% performance gain.

Change-Id: I8a2f8168f83d27ad9ace1b4b1a1e11cb83edf717
Reviewed-on: https://go-review.googlesource.com/80757
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Dim performance has regressed by 14% vs 1.9 on amd64.
Current pure go version of Dim is faster and,
what is even more important for performance, is inlinable, so
instead of tweaking asm implementation, just remove it.
I had to update BenchmarkDim, because it was simply reloading
constant(answer) in a loop.
Perf data below:

name   old time/op  new time/op  delta
Dim-6  6.79ns ± 0%  1.60ns ± 1%  -76.39%  (p=0.000 n=7+10)

If I modify benchmark to be the same as in this CL results are even better:

name   old time/op  new time/op  delta
Dim-6  10.2ns ± 0%   1.6ns ± 1%  -84.27%  (p=0.000 n=8+10)

Updates #21913

Change-Id: I00e23c8affc293531e1d9f0e0e49f3a525634f53
Reviewed-on: https://go-review.googlesource.com/80695
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Updates #22893.

Change-Id: I2cf5efb4fa6b77aaf82de5d8877c99f9aa5d519a
Reviewed-on: https://go-review.googlesource.com/81195
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

In nat.divLarge (having signature (z nat).divLarge(u, uIn, v nat)),
we check whether z aliases uIn or v, but aliasing is currently not
checked for the u parameter.

Unfortunately, z and u aliasing each other can in some cases cause
errors in the computation.

The q return parameter (which will hold the result's quotient), is
unconditionally initialized as

    q = z.make(m + 1)

When cap(z) ≥ m+1, z.make() will reuse z's backing array, causing q
and z to share the same backing array. If then z aliases u, setting q
during the quotient computation will then corrupt u, which at that
point already holds computation state.

To fix this, we add an alias(z, u) check at the beginning of the
function, taking care of aliasing the same way we already do for uIn
and v.

Fixes #22830

Change-Id: I3ab81120d5af6db7772a062bb1dfc011de91f7ad
Reviewed-on: https://go-review.googlesource.com/78995
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

The trace command computes IO, Schedule, Block, and Syscall profiles
by following the unblocking links in the execution trace and summing
up the duration.  This change offers variations of those profiles
that include only selected goroutine types. The id parameter takes the
goroutine type - i.e. pc of the goroutine.

The output is available from the /goroutine view. So, users can see
where the goroutines of interest typically block.

Also, these profiles are available for download so users can use
pprof or other tools to interpret the output. This change adds links
for download of global profile in the main page.

Change-Id: I35699252056d164e60de282b0406caf96d629c85
Reviewed-on: https://go-review.googlesource.com/75710Reviewed-by: Sameer Ajmani <sameer@golang.org>

Updates #18162 (mostly fixes)

Change-Id: I35bcb8a688bdaa432adb0ddbb73a2f7adda47b9e
Reviewed-on: https://go-review.googlesource.com/37958
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

I've been doing these tweaks by hand. I was going to write a tool in
Go for it, but it's not much additional shell here.

Fixes #22912
Updates #9797 (already closed)

Change-Id: Ia15bd9b6876e6f6a76aa9ca86b10f113095e96a3
Reviewed-on: https://go-review.googlesource.com/80895Reviewed-by: Ian Lance Taylor <iant@golang.org>

Updates #18162

Change-Id: I591fcf71a02678a99a56a6487da9689d3c9b1bb6
Reviewed-on: https://go-review.googlesource.com/37955
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Updates #18162

Change-Id: Iee854f48b2d1432955fdb462f2073ebbe76c34f8
Reviewed-on: https://go-review.googlesource.com/37957
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

GOMIPS is a GOARCH=mips{,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
'GOMIPS_{hardfloat,softfloat}'.

Note: GOMIPS will later also be used for a choice of MIPS instruction
set (mips32/mips32r2).

Updates #18162

Change-Id: I35417db8625695f09d6ccc3042431dd2eaa756a6
Reviewed-on: https://go-review.googlesource.com/37954
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

Fix a typo of "packageshlib" used for generating the link action ID.

Change-Id: Id6d39830908b03de658a58661030c32c592a1da9
Reviewed-on: https://go-review.googlesource.com/80935
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>

Compiler and linker changes to support DWARF inlined instances,
see https://go.googlesource.com/proposal/+/HEAD/design/22080-dwarf-inlining.md
for design details.

This functionality is gated via the cmd/compile option -gendwarfinl=N,
where N={0,1,2}, where a value of 0 disables dwarf inline generation,
a value of 1 turns on dwarf generation without tracking of formal/local
vars from inlined routines, and a value of 2 enables inlines with
variable tracking.

Updates #22080

Change-Id: I69309b3b815d9fed04aebddc0b8d33d0dbbfad6e
Reviewed-on: https://go-review.googlesource.com/75550
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

ORANGE node's Right node is the expression it is ranging over,
which is evaluated before the loop. In the escape analysis,
we should walk this node without loop depth incremented.

Fixes #21709.

Change-Id: Idc1e4c76e39afb5a344d85f6b497930a488ce5cf
Reviewed-on: https://go-review.googlesource.com/80740
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

This reverts commit a631daba.

Reason for revert: I was wrong. It still fails on the builders.

I don't know what's different about my VMWare VM, but on GCE it fails.

Change-Id: Ic6bee494b69235768bf08ba0bf59026bca41ad12
Reviewed-on: https://go-review.googlesource.com/80915Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #22778

Change-Id: I37f7a59c15828aa720fe787fff42fb3ef17729c7
Reviewed-on: https://go-review.googlesource.com/80815Reviewed-by: Ian Lance Taylor <iant@golang.org>

It must've been fixed since NetBSD 7.0. I can no longer reproduce it
with NetBSD 8-BETA (our new minimum NetBSD requirement).

Fixes #19293

Change-Id: I28f970ca41a53a037e1c6cddf1b7f286bda2d725
Reviewed-on: https://go-review.googlesource.com/80875
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The fix (CL 79575) for #18395 is too risky at this stage of the Go 1.10
release process.

Since issue #18395 is easily recognized (but not easily fixed), report
an error instead of silently continuing. This avoids inscrutable follow
on errors.

Also, make sure all empty interfaces are "completed", and adjust
printing code to report incomplete interfaces.

For #18395.

Change-Id: I7fa5f97ff31ac9775c9a6d318fce9f526b0350cd
Reviewed-on: https://go-review.googlesource.com/80455Reviewed-by: Alan Donovan <adonovan@google.com>

Fixes #22815.

Change-Id: Iaa54fa311bf2c0549a6316a0d51cc92425f5ba94
Reviewed-on: https://go-review.googlesource.com/80855Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #20650 (CL 45099 introduced the feature to x86).

Change-Id: If40cc9d87417a05281d8633f05cd91f6f434b136
Reviewed-on: https://go-review.googlesource.com/80843
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

In the x/arch repo, CL 45098 introduced SymLookup type, replacing
the unnamed function type for lookup functions. This affects the
signature of x86asm.GoSyntax. In particular, it cannot convert
one named type, namely lookupFunc, to the other without an
explicit cast. Make lookupFunc unnamed to fix.

Change-Id: I973300d29ef1dbfdbd7fc2429e89c5849e6a7329
Reviewed-on: https://go-review.googlesource.com/80842
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

For "type T = U" we were accidentally emitting a #define for "U__size"
instead of "T__size".

Fixes #22877.

Change-Id: I5ed6757d697753ed6d944077c16150759f6e1285
Reviewed-on: https://go-review.googlesource.com/80759
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The note about the single change workflow is included in the
git-codereview installation instructions, but it has nothing to do with
installing git-codereview. This note is more relevant for when a change
is actually being made.

Change-Id: Iccb90f3b7da87fab863fa4808438cd69a21a2fce
Reviewed-on: https://go-review.googlesource.com/76317Reviewed-by: Steve Francia <spf@golang.org>

Updates to x/net git rev a8b92947779 for CL 80755

Updates #22927

Change-Id: I84aad75afd954c9a6c57ad9a76328b99f1dc74a1
Reviewed-on: https://go-review.googlesource.com/80758
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Updates #22927
Updates #20852

Change-Id: I3ac0f8d38375d58a77781ab0e4f78ca57b258de0
Reviewed-on: https://go-review.googlesource.com/80756Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Several usages of tar (reasonably) just use the Header.FileInfo
to determine the type of the header. However, the os.FileMode type
is not expressive enough to represent "files" that are not files
at all, but some form of metadata.

Thus, Header{Typeflag: TypeXGlobalHeader}.FileInfo().Mode().IsRegular()
reports true, even though the expected result may have been false.

To reduce (not eliminate) the possibility of failure for such usages,
use the placeholder filename from the global PAX headers.
Thus, in the event the user did not handle special "meta" headers
specifically, they will just be written to disk as a regular file.

As an example use case, the "git archive --format=tgz" command produces
an archive where the first "file" is a global PAX header with the
name "global_pax_header". For users that do not explicitly check
the Header.Typeflag field to ignore such headers, they may end up
extracting a file named "global_pax_header". While it is a bogus file,
it at least does not stop the extraction process.

Updates #22748

Change-Id: I28448b528dcfacb4e92311824c33c71b482f49c9
Reviewed-on: https://go-review.googlesource.com/78355Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

For #22695.

Change-Id: Idcda3294070aeaeaf940aaf2014b573732fd60a4
Reviewed-on: https://go-review.googlesource.com/80696Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Dmitri Shuralyov <shurcool@gmail.com>

This CL is a simple doc typo fix, uncovered while reviewing the go-wasm
port.

Change-Id: I0fce915c341aaaea3a7cc365819abbc5f2c468c3
Reviewed-on: https://go-review.googlesource.com/80715Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Return an error when a user passes -o and -buildmode=exe to build a package
without a main.

Fixes #20017.

Change-Id: I07d49c75e7088a96f00afe18c9faa842c5d71afb
Reviewed-on: https://go-review.googlesource.com/49371
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

In order to avoid a regression where the date of the ModTime method
changed behavior, simply preserve the old behavior of determining
the date based on the legacy fields.

This ensures that anyone relying on ModTime before Go1.10 will have
the exact same behavior as before.
New users should use FileHeader.Modified instead.

We keep the UTC coersion logic in SetModTime since some users
manually compute timezone offsets in order to have precise control
over the MS-DOS time field.

Fixes #22738

Change-Id: Ib18b6ebd863bcf645748e083357dce9bc788cdba
Reviewed-on: https://go-review.googlesource.com/78031Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

A method is more in keeping with the rest of the Writer API and
incidentally allows the comment error to be reported earlier.

Fixes #22737.

Change-Id: I1eee2103a0720c76d0c394ccd6541e6219996dc0
Reviewed-on: https://go-review.googlesource.com/79415
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

If there are no more requests being made, wait to shut down
the response-writing codec until the pending requests are all
answered.

Fixes #17239.

Change-Id: Ie62c63ada536171df4e70b73c95f98f778069972
Reviewed-on: https://go-review.googlesource.com/79515
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>