Some real world JPEG images are in 4:1:1 and 4:1:0 formats.

See also http://en.wikipedia.org/wiki/Chroma_subsampling

Change-Id: I2d51a41944f581cf11f4ab975046b1737271842f
Reviewed-on: https://go-review.googlesource.com/5838Reviewed-by: Rob Pike <r@golang.org>

There are no behavior changes in this CL, only specifying the status
quo. A follow-up CL, https://go-review.googlesource.com/#/c/5910/, will
change marshaling behavior.

Change-Id: Ib3f4d62e8c4758da2f11a6d26b285c10d3b0d98a
Reviewed-on: https://go-review.googlesource.com/6040Reviewed-by: Andrew Gerrand <adg@golang.org>

The existing Hostname function uses the GetComputerName system
function in windows to determine the hostname. It has some downsides:

  - The name is limited to 15 characters.
  - The name returned is for NetBIOS, other OS's return a DNS name

This change adds to the internal/syscall/windows package a
GetComputerNameEx function, and related enum constants. They are used
instead of the syscall.ComputerName function to implement os.Hostname
on windows.

Fixes #9982

Change-Id: Idc8782785eb1eea37e64022bd201699ce9c4b39c
Reviewed-on: https://go-review.googlesource.com/5852Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Carlos Castillo <cookieo9@gmail.com>
Reviewed-by: Yasuhiro MATSUMOTO <mattn.jp@gmail.com>

Change-Id: I9b78085adc12cbd240d0b8b48db6810ddb2aeadd
Reviewed-on: https://go-review.googlesource.com/5991Reviewed-by: Alan Donovan <adonovan@google.com>

Change-Id: Ie8310acc783659497e50dfe629f06d655b51d647
Reviewed-on: https://go-review.googlesource.com/5990Reviewed-by: Alan Donovan <adonovan@google.com>

Change-Id: Ie37673d4af2fa7476d67ffb686641611ab6a8e6b
Reviewed-on: https://go-review.googlesource.com/5930Reviewed-by: Alan Donovan <adonovan@google.com>

Macro definition ordering.

Change-Id: I0def4702d19a21a68ffa52ea5b7c22578830c578
Reviewed-on: https://go-review.googlesource.com/6030Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

Gives tests a way to find the bundle that contains their testdata, and
is generally useful for finding resources.

Change-Id: Idfa03e8543af927c17bc8ec8aadc5014ec82df28
Reviewed-on: https://go-review.googlesource.com/6000Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

Updates #10002

The gdb test added in 1c82e236 is failing on most arm systems.

Temporarily disable this test so that we can return to a working arm build.

Change-Id: Iff96ea8d5a99e1ceacf4979e864ff196e5503535
Reviewed-on: https://go-review.googlesource.com/5902Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Iee319c9f5375c172fb599da77234c10ccb0fd314
Reviewed-on: https://go-review.googlesource.com/6020Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I42929abe5cefd84a1daf4f36ee1806c490ce16ec
Reviewed-on: https://go-review.googlesource.com/5960Reviewed-by: Minux Ma <minux@golang.org>

We return memory to the kernel with madvise(..., DONTNEED).
Also mark returned memory with NOHUGEPAGE to keep the kernel from
merging this memory into a huge page, effectively reallocating it.

Only known to be a problem on linux/{386,amd64,amd64p32} at the moment.
It may come up on other os/arch combinations in the future.

Fixes #8832

Change-Id: Ifffc6627a0296926e3f189a8a9b6e4bdb54c79eb
Reviewed-on: https://go-review.googlesource.com/5660Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

We need to distinguish pointers to free spans, which indicate bugs in
our pointer analysis, from pointers to never-in-the-heap spans, which
can legitimately arise from sysAlloc/mmap/etc.  This normally isn't a
problem because the heap is contiguous, but in some situations (32
bit, particularly) the heap must grow around an already allocated
region.

The bad pointer test is disabled so this fix doesn't actually do
anything, but it removes one barrier from reenabling it.

Fixes #9872.

Change-Id: I0a92db4d43b642c58d2b40af69c906a8d9777f88
Reviewed-on: https://go-review.googlesource.com/5780Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

Each architecture had its own Dconv (operand printer) but the syntax is
close to uniform and the code overlap was considerable. Consolidate these
into a single top-level function. A similar but smaller unification is done
for Mconv ("Name" formatter) as well.

The signature is changed. The flag was unused so drop it. Add a
function argument, Rconv, that must be supplied by the caller.
TODO: A future change will unify Rconv as well and this argument
will go away.

Some formats changed, because of the automatic consistency
created by unification. For instance, 0(R1) always prints as (R1)
now, and foo+0(SB) is just foo(SB). Before, some made these
simplifications and some didn't; now they all do.

Update the asm tests that depend on the format.

Change-Id: I6e3310bc19814c0c784ff0b960a154521acd9532
Reviewed-on: https://go-review.googlesource.com/5920Reviewed-by: Russ Cox <rsc@golang.org>

Fixes #9083.

Change-Id: Ifbdebafb39a73a1dacf7e67171e8e88028d1f10b
Reviewed-on: https://go-review.googlesource.com/1219Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Chris Manghane <cmang@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Available darwin/arm devices sporadically have trouble mapping 256M.

I would really appreciate it if anyone could check my working on
this, and make sure sure there aren't obviously bad consequences I
haven't considered.

Change-Id: Id1a8edae104d974fcf5f9333274f958625467f79
Reviewed-on: https://go-review.googlesource.com/5752Reviewed-by: Keith Randall <khr@golang.org>

Fixes #9076.

Change-Id: Ib41a452fa9aa9fecf19f65c36d13715923548041
Reviewed-on: https://go-review.googlesource.com/1250Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Chris Manghane <cmang@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #9017.

Change-Id: I26cb1e7d6e137ff145773169cfe2d8bd4e1b339c
Reviewed-on: https://go-review.googlesource.com/1252Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Chris Manghane <cmang@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Also introduce actual data structure for table.

Change-Id: I6bbe9aff8a872ae254f3739ae4ca17f7b5c4507a
Reviewed-on: https://go-review.googlesource.com/5701Reviewed-by: Rob Pike <r@golang.org>

The dummy implementation was causing lots of argument lists
to be prepared and thrown away.

Change-Id: Id0040dec6b0937f3daa8a8d8911fa3280123e863
Reviewed-on: https://go-review.googlesource.com/5700Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Change-Id: I50e83248357928e56c94b88a8764de828f4f5c76
Reviewed-on: https://go-review.googlesource.com/5890Reviewed-by: Alan Donovan <adonovan@google.com>

verifyAsm is still on, but this CL changes the order to asm then 6a.
Before, it was 6a then asm, but that meant that any bugs in asm
for bad input would be prevented from happening because 6a would
catch them. Now asm gets first crack, as it must.

Also implement the -trimpath flag in asm. It's necessary and trivial.

Change-Id: Ifb2ab870de1aa1b53dec76a78ac697a0d36fa80a
Reviewed-on: https://go-review.googlesource.com/5850Reviewed-by: Russ Cox <rsc@golang.org>

Change-Id: If516e12d4b5dfb6f9288437d270569f7e4e2a1cd
Reviewed-on: https://go-review.googlesource.com/5871Reviewed-by: Alan Donovan <adonovan@google.com>

Change-Id: I6514f69b979d064b6a3c4b5d0828cc94f485cac2
Reviewed-on: https://go-review.googlesource.com/5694Reviewed-by: Russ Cox <rsc@golang.org>

Missing cases for JMP $4 and foo+4(SB):AX. Both are odd but 8a accepts them
and they seem valid.

Change-Id: Ic739f626fcc79ace1eaf646c5dfdd96da59df165
Reviewed-on: https://go-review.googlesource.com/5693Reviewed-by: Russ Cox <rsc@golang.org>

Since allglock is held in this function, there's no point to
tip-toeing around allgs.  Just use a for-range loop.

Change-Id: I1ee61c7e8cac8b8ebc8107c0c22f739db5db9840
Reviewed-on: https://go-review.googlesource.com/5882Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>

Previously, we had three loops in the garbage collector that all
cleared the per-G GC flags.  Consolidate these into one function.
This one function is designed to work in a concurrent setting.  As a
result, it's slightly more expensive than the loops it replaces during
STW phases, but these happen at most twice per GC.

Change-Id: Id1ec0074fd58865eb0112b8a0547b267802d0df1
Reviewed-on: https://go-review.googlesource.com/5881Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>

The loop in gcMark is redundant with the gcworkdone resetting
performed by markroot, which called a few lines later in gcMark.

Change-Id: Ie0a826a614ecfa79e6e6b866e8d1de40ba515856
Reviewed-on: https://go-review.googlesource.com/5880Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>

Package runtime's Go code was converted to directly call getcallerpc
and getcallersp in https://golang.org/cl/138740043, but the assembly
implementations were not removed.

Change-Id: Ib2eaee674d594cbbe799925aae648af782a01c83
Reviewed-on: https://go-review.googlesource.com/5901
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

NetBSD's semaphore implementation is derived from OpenBSD's, but has
subsequently diverged due to cleanups that were only applied to the
latter (https://golang.org/cl/137960043, https://golang.org/cl/5563).
This CL applies analogous cleanups for NetBSD.

Notably, we can also remove the scary NetBSD deadlock warning.
NetBSD's manual pages document that lwp_unpark on a not-yet-parked LWP
will cause that LWP's next lwp_park system call to return immediately,
so there's no race hazard.

Change-Id: Ib06844c420d2496ac289748eba13eb4700bbbbb2
Reviewed-on: https://go-review.googlesource.com/5564Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Joel Sing <jsing@google.com>

Updates #9974

The *at family of syscalls requires some constants to be defined in the
syscall package for linux. Add the necessary constants and regenerate
the ztypes_linux_*.go files.

Change-Id: I6df343fef7bcacad30d36c7900dbfb621465a4fe
Reviewed-on: https://go-review.googlesource.com/5836Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

(gdb) p x
Python Exception <class 'gdb.error'> There is no member named b.:
$2 = map[string]string
->
(gdb) p x
$1 = map[string]string = {["shane"] = "hansen"}

Change-Id: I874d02a029f2ac9afc5ab666afb65760ec2c3177
Reviewed-on: https://go-review.googlesource.com/5522Reviewed-by: Ian Lance Taylor <iant@golang.org>

OpenBSD's thrsleep system call includes an "abort" parameter, which
specifies a memory address to be tested after being registered on the
sleep channel (i.e., capable of being woken up by thrwakeup).  By
passing a pointer to waitsemacount for this parameter, we avoid race
conditions without needing a lock.  Instead we just need to use
atomicload, cas, and xadd to mutate the semaphore count.

Change-Id: If9f2ab7cfd682da217f9912783cadea7e72283a8
Reviewed-on: https://go-review.googlesource.com/5563Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Joel Sing <jsing@google.com>

Updates #9974

This proposal moves the definition of Dup2 from the generic syscall_linux.go
to the GOOS specific variants. This is in preparation for the arm64 port.

For all existing platforms Dup2 is not affected. When arm64 is added we'll use
either a forwarding method to Dup3 or

	//sysnb        Dup2(oldfd int, newfd int) (err error) = SYS_DUP3

Because mksycall.pl does not sort symbols before generating the output file
the diff includes some unavoidable code moves as Dup2 is processed latter in
the run.

Discussion: https://groups.google.com/forum/#!topic/golang-dev/zpeFtN2z5Fc

Change-Id: Icdedf55bb29e749c4230e1ee371bf9d0bd0cfb38
Reviewed-on: https://go-review.googlesource.com/5835Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>

https://go-review.googlesource.com/#/c/5691/ shouldn't affect anyone
because it reflects the RFC and behaviour of modern browsers, but it's
probably worth mentioning.

Change-Id: I8a8eedaac5226b1d8018dc56de6b2d41bd82a642
Reviewed-on: https://go-review.googlesource.com/5862Reviewed-by: Rob Pike <r@golang.org>

Change-Id: Ia92eea833283f8b16fa09d4ca1c9cb3bc0eb18a2
Reviewed-on: https://go-review.googlesource.com/5870Reviewed-by: Rob Pike <r@golang.org>

Updates #9974

This proposal moves the definition of Pipe an Pipe2 from the generic
syscall_linux.go to the GOOS specific variants. This is in preparation
for the arm64 port.

For platforms where pipe2(2) is not supported in the minimum 2.6.23 kernel,
amd64 and 386, we retain pipe(2). For all other platforms pipe(2) is removed
and Pipe forwards to pipe2(2).

Because mksycall.pl does not sort symbols before generating the output file
the diff includes some unavoidable code moves as Pipe and Pipe2 are processed
latter in the run.

Discussion: https://groups.google.com/forum/#!topic/golang-dev/zpeFtN2z5Fc

Change-Id: Ie26d6761eeb9760dbaff974ee8bc0d57a9ceaee4
Reviewed-on: https://go-review.googlesource.com/5833Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

This is a reproposal of CL 2957. This reproposal restricts the
scope of this change to just arm systems.

With respect to rsc's comments on 2957, on all my arm hosts they perform
the build significantly faster with this change in place.

Change-Id: Ie09be1a73d5bb777ec5bca3ba93ba73d5612d141
Reviewed-on: https://go-review.googlesource.com/5834Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

When GODEBUG=gctrace=2 two gcs are preformed. During the first gc
the stack scan sets the g's gcscanvalid and gcworkdone flags to true
indicating that the stacks have to be scanned and do not need to
be rescanned. These need to be reset to false for the second GC so the
stacks are rescanned, otherwise if the only pointer to an object is
on the stack it will not be discovered and the object will be freed.
Typically this will include the object that was just allocated in
the mallocgc call that initiated the GC.

Change-Id: Ic25163f4689905fd810c90abfca777324005c02f
Reviewed-on: https://go-review.googlesource.com/5861Reviewed-by: Russ Cox <rsc@golang.org>

Rebuild the zsyscall_linux_*.go files in preperation for #9974

The only change is the ppc64/ppc64le files which were not rebuilt when
syscall.use was added.

Change-Id: I804c63731e4900c782025de04ea3585d99688958
Reviewed-on: https://go-review.googlesource.com/5831Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>