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>

Change-Id: If6eb3a7c9ad48a517e584567b1003479c1df6cca
Reviewed-on: https://go-review.googlesource.com/32136Reviewed-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>

Fixes #17686.

Change-Id: I7d07c367e50b448579f9855bea43df76ddb82bd0
Reviewed-on: https://go-review.googlesource.com/32420Reviewed-by: Rob Pike <r@golang.org>

Does not handle imports of packages with exported aliases yet.

For #17592.

Change-Id: Iee63fb9d521014995003a417271fbe0384ae04ef
Reviewed-on: https://go-review.googlesource.com/32108Reviewed-by: Alan Donovan <adonovan@google.com>

The map[typeOff]*_type object is created at run time and stored in
the moduledata. The moduledata object is marked by the linker as
SNOPTRDATA, so the reference is ignored by the GC. Running
misc/cgo/testplugin/test.bash with GOGC=1 will eventually collect
the typemap and crash.

This bug probably comes up in -linkshared binaries in Go 1.7.
I don't know why we haven't seen a report about this yet.

Fixes #17680

Change-Id: I0e9b5c006010e8edd51d9471651620ba665248d3
Reviewed-on: https://go-review.googlesource.com/32430
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Plumb the import path of a plugin package through to the linker, and
use it as the prefix on the exported symbol names.

Before this we used the basename of the plugin file as the prefix,
which could conflict and result in multiple loaded plugins sharing
symbols that are distinct.

Fixes #17155
Fixes #17579

Change-Id: I7ce966ca82d04e8507c0bcb8ea4ad946809b1ef5
Reviewed-on: https://go-review.googlesource.com/32355Reviewed-by: Ian Lance Taylor <iant@golang.org>

Previously, we were off by one.

Also fix a comment typo.

Change-Id: Ib94d23acc56d5fccd44144f71655481f98803ac8
Reviewed-on: https://go-review.googlesource.com/32149Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This is convenient for direct use of `go tool cgo`. We can also use it
from the go tool to reduce the length of the file names that cgo
generates.

Update #17070.

Change-Id: I8466a0a2cc68a732d17d07319e303497715bac8c
Reviewed-on: https://go-review.googlesource.com/32354
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

Disabled by https://golang.org/cl/53020044 due to false positives.
Reenable and model properly.

Fixes #17306.

Change-Id: I28405ddfcd17f58cf1427c300273212729154359
Reviewed-on: https://go-review.googlesource.com/31589
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

This field is a zero length array and has little use. Since Go 1.5, trailing
zero-length arrays take up space. Both syscall.UnixRights() and
syscall.ParseSocketControlMessage() depend on being able to do an unsafe cast
of socket control message data to Cmsghdr this is only safe if the socket
control message data is greater than or equal to the size of Cmsghdr. Since
control message data that is equal in size to Cmsghdr without X__cmsg_data is
a valid socket control message, we must remove X__cmsg_data or not perform the
unsafe cast.

Removing X__cmsg_data will prevent Go code that uses X__cmsg_data from
compiling, but removing the unsafe cast will cause Go code that uses
X__cmsg_data to fail or exhibit undefined behavior at runtime. It was
therefore decided that removing X__cmsg_data was the better option.

Fixes #17649

Change-Id: I39f323f978eca09d62da5785c5c5c9c7cbdf8c31
Reviewed-on: https://go-review.googlesource.com/32319Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Prior to this change, it was implied that transaction properties
would be carried in the context value. However, no such properties
were defined, not even common ones. Define two common properties:
isolation level and read-only. Drivers may choose to support
additional transaction properties. It is not expected any
further transaction properties will be added in the future.

Change-Id: I2f680115a14a1333c65ba6f943d9a1149d412918
Reviewed-on: https://go-review.googlesource.com/31258
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This updates the runtime to HEAD to keep it aligned and fixes some bugs.

http://llvm.org/viewvc/llvm-project?view=revision&revision=285454
fixes the crash on darwin related to unaligned data section (#17065).

http://llvm.org/viewvc/llvm-project?view=revision&revision=285451
enables core dumps by default (#16527).

http://llvm.org/viewvc/llvm-project?view=revision&revision=285455
adds a hook to obtain number of races reported so far (#15972).
Can now be obtained with:

//go:nosplit
func RaceReportCount() int {
	var n uint64
	racecall(&__tsan_report_count, uintptr(unsafe.Pointer(&n)), 0, 0, 0)
	return int(n)
}

Fixes #16527.
Fixes #17065.
Update #15972.

Change-Id: I8f869cb6275c9521a47303f3810a9965e9314357
Reviewed-on: https://go-review.googlesource.com/32160
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

No point in computing this info on startup.
Compute it at build time.
This lets us spend more time computing & checking the size classes.

Improve the div magic for rounding to the start of an object.
We can now use 32-bit multiplies & shifts, which should help
32-bit platforms.

The static data is <1KB.

The actual size classes are not changed by this CL.

Change-Id: I6450cec7d1b2b4ad31fd3f945f504ed2ec6570e7
Reviewed-on: https://go-review.googlesource.com/32219
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

This fixes systems for which ccache is the default compiler.

Also remove a couple of temporary files created by TestImportMain.

Fixes #17668.

Change-Id: I1edefdcec5f417be0533c146253c35ff4928c1c0
Reviewed-on: https://go-review.googlesource.com/32328Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Provides redirection support for 307, 308 server statuses.
Provides redirection support for DELETE method.

Updates old tests that assumed all redirects were treated
the way 301, 302 and 303 are processed.

Fixes #9348
Fixes #10767
Fixes #13994

Change-Id: Iffa8dbe0ff28a1afa8da59869290ec805b1dd2c4
Reviewed-on: https://go-review.googlesource.com/29852
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Iec469846dc8b5a747ad81690000f1f6f53721ea1
Reviewed-on: https://go-review.googlesource.com/32372Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The GZIP format records the ModTime as an uint32 counting seconds since
the Unix epoch. The zero value is explicitly defined in section 2.3.1
as meaning no timestamp is available.

Currently, the Writer always encodes the ModTime even if it is the zero
time.Time value, which causes the Writer to try and encode the value
-62135596800 into the uint32 MTIME field. This causes an overflow and
results in our GZIP files having MTIME fields indicating a date in 2042-07-13.

We alter the Writer to only encode ModTime if the value does not underflow
the MTIME field (i.e., it is newer than the Unix epoch). We do not attempt
to fix what happens when the timestamp overflows in the year 2106.

We alter the Reader to only decode ModTime if the value is non-zero.
There is no risk of overflowing time.Time when decoding.

Fixes #17663

Change-Id: Ie1b65770c6342cd7b14aeebe10e5a49e6c9eb730
Reviewed-on: https://go-review.googlesource.com/32325Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Updates http2 to x/net git rev 76c1a11e for:

     http2: initialize Server.IdleTimeout from http.Server as http1 does
     https://golang.org/cl/32230

     http2: change how Server.IdleTimeout is initialized from http.Server
     https://golang.org/cl/32323

Fixes #14204

Change-Id: I099f89fcd0d8bc0e42da163ae0a3b786fd81292f
Reviewed-on: https://go-review.googlesource.com/32322
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Because git.

Change-Id: Ia1e7c6ba0e8c4d47f993487d2483cbb213b465e5
Reviewed-on: https://go-review.googlesource.com/32351
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>