Adds the runtime initialization flow for arm akin to amd64.
In particular,we use the library initialization entry point to:
    - create a new OS thread and run the "regular" runtime init stack on
      that thread
    - return immediately from the main (i.e., loader) thread
    - at the first CGO invocation, we wait for the runtime initialization
      to complete.

Verified to work on a Raspberry Pi and an Android phone.

Change-Id: I32f39228ae30a03ce9569287f234b305790fecf6
Reviewed-on: https://go-review.googlesource.com/8455Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Srdjan Petrovic <spetrovic@google.com>

Change-Id: I1668a6885c45180ff88fe673d04cec7eba395ee7
Reviewed-on: https://go-review.googlesource.com/8861Reviewed-by: Ian Lance Taylor <iant@golang.org>

Related to issue #10410

For some reason, any non-trivial code in _cgo_wait_runtime_init_done
(even fprintf()) will crash that call.

If anybody has any guess why this is happening, please let me know!

For now, I'm clearing the functions for ppc64, as it's currently not used.

Change-Id: I1b11383aaf4f9f9a16f1fd6606842cfeedc9f0b3
Reviewed-on: https://go-review.googlesource.com/8766Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Srdjan Petrovic <spetrovic@google.com>

This is friendlier for manual runs and personal devices.
Builders will pass -restart.

Fixes #10333.

Change-Id: Ia64c8f1660e275b5a1543d7f81f5f5efb623182f
Reviewed-on: https://go-review.googlesource.com/8870Reviewed-by: David Crawshaw <crawshaw@golang.org>

Change-Id: I469254384b0f4e5b5f08a18658934e19259935f9
Reviewed-on: https://go-review.googlesource.com/8718Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Ia9ff9c0d381fad43fc5d3e5972dd6e66503733a5
Reviewed-on: https://go-review.googlesource.com/8815Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ibaba67980db6e05aa71568199b2dac2fcaa86fd6
Reviewed-on: https://go-review.googlesource.com/8824Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: I5ed26975670d4189a46b585a56c66c199905d168
Reviewed-on: https://go-review.googlesource.com/8823Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ic75927bd6457d37cda7dd8279fd9b4cd52edc1d1
Reviewed-on: https://go-review.googlesource.com/8813Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm, the test devices can only install and execute
a single app at a time.

Change-Id: I74e6130ef83537c465b4585a366d02953fd907bf
Reviewed-on: https://go-review.googlesource.com/8827Reviewed-by: Minux Ma <minux@golang.org>

Like other arm64 platforms, darwin/arm64 has a different physical
page size to logical page size so it is running into issue 9993. I
hope it can be fixed for Go 1.5, but for now it is demonstrating the
same bug as the other skipped os+arch combinations.

Change-Id: Iedaf9afe56d6954bb4391b6e843d81742a75a00c
Reviewed-on: https://go-review.googlesource.com/8814Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ib0438021bfe9eb105222b93e5bb375c282cc7b8c
Reviewed-on: https://go-review.googlesource.com/8822Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ic5c6c0b2fdbb89f4579677e120a8f2dbf300e5b9
Reviewed-on: https://go-review.googlesource.com/8820Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: I1a9f51c572c14b78d35ea62f52927f2bdc46e4c0
Reviewed-on: https://go-review.googlesource.com/8821Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ia8c912e91259a5073aa3ab2b6509a18aa9a1fce7
Reviewed-on: https://go-review.googlesource.com/8818Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: I4b0ab4a104f2c8a821ca8b5fa8d266e51883709f
Reviewed-on: https://go-review.googlesource.com/8816Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ie4998d24b2d891a9f6c8047ec40cd3fdf80622cd
Reviewed-on: https://go-review.googlesource.com/8812Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ib9a32bb0aed5f08b27de11a93aaf273cacdf5779
Reviewed-on: https://go-review.googlesource.com/8819Reviewed-by: Minux Ma <minux@golang.org>

Previously, running

  $ go get -u -v golang.org/x/tools/cmd/godoc

would results in dozens of HTTP requests for

  https://golang.org/x/tools?go-get=1

once per package under x/tools.

Now it caches the results. We still end up doing one HTTP request for
all the packages under x/tools, but this reduces the total number of
HTTP requests in ~half.

This also moves the singleflight package back into an internal
package. singleflight was originally elsewhere as a package, then got
copied into "net" (without its tests). But now that we have internal,
put it in its own package, and restore its test.

Fixes #9249

Change-Id: Ieb5cf04fc4d0a0c188cb957efdc7ea3068c34e3f
Reviewed-on: https://go-review.googlesource.com/8727Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I9654a5c85bd9b3ae9c7a9eddaef1ec752f42bd1b
Reviewed-on: https://go-review.googlesource.com/8840Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The background index in the global palette (located in the image.Config)
is necessary for interpreting GIF frames properly

Frame disposal information is necessary for interpreting GIF frames in
the context of a sequence (or animation)

Removes decoder.flags as it can be a local variable

Change-Id: I6790a7febf6ba0859175c834c807bc6413e6b194
Reviewed-on: https://go-review.googlesource.com/4620Reviewed-by: Nigel Tao <nigeltao@golang.org>

Float type from a mutex to atomic bit array in a manner akin to
Google Guava's AtomicDouble[0], including adding a benchmark for the
type (benchcmp included below) along with some expvar_test.go cruft
being fixed.

benchmark             old ns/op     new ns/op     delta
BenchmarkFloatSet     115           9.37          -91.85%
BenchmarkFloatAdd     114           17.1          -85.00%

benchmark             old allocs     new allocs     delta
BenchmarkFloatSet     0              0              +0.00%
BenchmarkFloatAdd     0              0              +0.00%

benchmark             old bytes     new bytes     delta
BenchmarkFloatSet     0             0             +0.00%
BenchmarkFloatAdd     0             0             +0.00%

[0] - http://goo.gl/m4dtlI

Change-Id: I4ce6a913734ec692e3ed243f6e6f7c11da4c6036
Reviewed-on: https://go-review.googlesource.com/3687Reviewed-by: Rob Pike <r@golang.org>

This test checks the working directory is
always consistent after Chdir in a Go program.

Fixes #10035.

Change-Id: I6abf0e4fcd40680ee572c6b40fc52ab17ef38d54
Reviewed-on: https://go-review.googlesource.com/6382Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

In Plan 9, goroutines can run in different processes,
which don't share their working directory. However,
Go expects the working directory to be program-wide.

We use a Fixwd function to fix the working directory
before calling system calls which depend on the
working directory.

In fixwdLocked, the working directory is not fixed
when getwd returns an error. However, an error can
happen is some cases, notably when the directory
has been previously removed in another process.

Fixes #10422.

Change-Id: Ie0c36f97c4b5ebe27ff0ead360987c5b35f825e4
Reviewed-on: https://go-review.googlesource.com/8800Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Ic453da17817f66e1073f6ba740b830b8daf2fc38
Reviewed-on: https://go-review.googlesource.com/8829Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Currently, Entry has a Val method that looks up an attribute and
returns its value. Now that Field has more fields than the attribute
and its value, it's useful to return the whole Field and let the
caller retrieve the parts it needs.

This change adds an AttrField method to Entry that does the same
lookup at Val, but returns the whole *Field rather than just the
value.

Change-Id: Ic629744c14c0e09d7528fa1026b0e1857789948c
Reviewed-on: https://go-review.googlesource.com/8503Reviewed-by: Ian Lance Taylor <iant@golang.org>

To return DWARF attribute values, debug/dwarf maps the DWARF attribute
value classes to Go types. Unfortunately, this mapping is ambiguous in
a way that makes it impossible to correctly interpret some DWARF
attributes as of DWARF 4. For example, AttrStartScope can be either a
constant or a rangelistptr. The attribute is interpreted differently
depending on its class, but debug/dwarf maps both classes to int64, so
the caller can't distinguish them from the Go type.
AttrDataMemberLocation is similar.

To address this, this change adds a field to type Field that indicates
the exact DWARF attribute value class of that field's value. This
makes it possible to distinguish value classes that can't be
distinguished by their Go type alone.

The root of this type ambiguity was DWARF itself. For example, DWARF 2
made no distinction between constants that were just constants and
constants that were section offsets because no attribute could have
both meanings. Hence, the single int64 type was sufficient. To avoid
introducing just another layer of ambiguity, this change takes pains
to canonicalize ambiguous classes in DWARF 2 and 3 files into the
unambiguous classes of DWARF 4.

Of course, there's no guarantee that future DWARF versions won't do
the same thing again and further subdivide the DWARF 4 classes. This
change gets ahead of this somewhat by distinguishing the various *ptr
classes even though the encoding does not. If there's some other form
of split, we can handle this in a backwards-compatible way by
introducing, for example, a Class5 field and type.

Change-Id: I4ef96d1223b0fd7f96ecf44fcc0e704a36af02b4
Reviewed-on: https://go-review.googlesource.com/8502Reviewed-by: Ian Lance Taylor <iant@golang.org>

Uses ar to create an archive when -buildmode=c-archive.

A small example (that I hope to turn into a test in a later CL):

goarchive.go:
	package main

	import "fmt"

	import "C"

	func init() {
		fmt.Println("ran go init")
	}

	//export FuncInGo
	func FuncInGo() {
		fmt.Println("called a go function")
	}

	func main() {
		fmt.Println("in main")
	}

This can be compiled with:

	go build -ldflags=-buildmode=c-archive -o=libgo.a goarchive.go

main.c:

	#include <stdio.h>

	extern void FuncInGo();

	int main(void) {
		printf("c hello\n");
		FuncInGo();
		printf("c goodbye\n");
		return 0;
	}

Can be compiled with:

	cc main.c libgo.a

Apple provide a warning about the lack of PIE, but still produce a
binary which runs and outputs (on darwin/amd64):

	c hello
	ran go init
	called a go function
	c goodbye

Change-Id: I7611925f210a83afa6bd1e66a5601dd636a428c8
Reviewed-on: https://go-review.googlesource.com/8711Reviewed-by: Ian Lance Taylor <iant@golang.org>

Tested by using -buildmode=c-archive to generate an archive, add it
to an Xcode project and calling a Go function from an iOS app. (I'm
still investigating proper buildmode tests for all.bash.)

Change-Id: I7890df15246df8e90ad27837b8d64ba2cde409fe
Reviewed-on: https://go-review.googlesource.com/8719Reviewed-by: Ian Lance Taylor <iant@golang.org>

Just like darwin/arm.

Change-Id: Ia84662f58f6b1bb168cce8a9837945b1cbd175e1
Reviewed-on: https://go-review.googlesource.com/8828Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm, cannot fork..

Change-Id: If565afbceb79013b9e3103e1e28d93691e9fc0a5
Reviewed-on: https://go-review.googlesource.com/8826Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Iadc30b7307ae56fd4f8a681d49672bed7ca6966f
Reviewed-on: https://go-review.googlesource.com/8810Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Iabb6282f18548da43117ee60f7ad6e272502f09d
Reviewed-on: https://go-review.googlesource.com/8825Reviewed-by: Minux Ma <minux@golang.org>

Just like darwin/arm.

Change-Id: Ib64a3e8ff11249a20b0208bd3b900db318c682b7
Reviewed-on: https://go-review.googlesource.com/8817Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Similar to darwin/arm. This issue is quite worrying and I hope it
can be addressed for Go 1.5.

Change-Id: Ic095281d6a2e9a38a59973f58d464471db5a2edc
Reviewed-on: https://go-review.googlesource.com/8811Reviewed-by: Minux Ma <minux@golang.org>

Change-Id: Ia49ab729747acb07bf392d90aea9e752471e152e
Reviewed-on: https://go-review.googlesource.com/8789Reviewed-by: Minux Ma <minux@golang.org>

Change-Id: Id469165b1acd383837b1f4e1e6f961e10dfa5d61
Reviewed-on: https://go-review.googlesource.com/8332Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

While here, this changes DWAbbrev's attr field from a [30]DWAttrForm
with zero-termination to a simple []DWAttrForm, and updates its users
accordingly.

Passes "go build -toolexec 'toolstash -cmp' -a std" on linux/amd64.

Change-Id: I52b5f7a749bdb3e7588fc8ebdb8fee2cf8cab602
Reviewed-on: https://go-review.googlesource.com/8762
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

Change-Id: I440435927fc9f417d81ed4e8656a73787bf0968a
Reviewed-on: https://go-review.googlesource.com/8801Reviewed-by: Ian Lance Taylor <iant@golang.org>

The symbols for the actual data in a constant string or bytes literal should
be local.

Change-Id: Idafcfba9a638eaa4e460e5103d96843960559b35
Reviewed-on: https://go-review.googlesource.com/8772Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>