Add support for the context function set by runtime.SetCgoTraceback.
The context function was added in CL 17761, without support.
This CL is the support.

This CL has not been tested for real C code, as a working context
function for C code requires unwind support that does not seem to exist.
I wanted to get the CL out before the freeze.

I apologize for the length of this CL.  It's mostly plumbing, but
unfortunately the plumbing is processor-specific.

Change-Id: I8ce11a0de9b3dafcc29efd2649d776e93bff0e90
Reviewed-on: https://go-review.googlesource.com/22508Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This is a subset of https://golang.org/cl/20022 with only the copyright
header lines, so the next CL will be smaller and more reviewable.

Go policy has been single space after periods in comments for some time.

The copyright header template at:

    https://golang.org/doc/contribute.html#copyright

also uses a single space.

Make them all consistent.

Change-Id: Icc26c6b8495c3820da6b171ca96a74701b4a01b0
Reviewed-on: https://go-review.googlesource.com/20111
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This is Part 2 of the change, see Part 1 here: in https://go-review.googlesource.com/#/c/7692/

Suggested by iant@, 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.

The above mechanism is implemented only on linux_amd64.  Next step is to
support it on linux_arm.  Other platforms don't yet support shared library
compiling/linking, but we intend to use the same strategy there as well.

Change-Id: Ib2c81b1b83bee837134084b75a3beecfb8de6bf4
Reviewed-on: https://go-review.googlesource.com/8094
Run-TryBot: Srdjan Petrovic <spetrovic@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The Go builders (and standard development cycle) for programs on iOS
require running the programs under lldb. Unfortunately lldb intercepts
SIGSEGV and will not give it back.

https://llvm.org/bugs/show_bug.cgi?id=22868

We get around this by never letting lldb see the SIGSEGV. On darwin,
Unix signals are emulated on top of mach exceptions. The debugger
registers a task-level mach exception handler. We register a
thread-level exception handler which acts as a faux signal handler.
The thread-level handler gets precedence over the task-level handler,
so we can turn the exception EXC_BAD_ACCESS into a panic before lldb
can see it.

Fixes #10043

Change-Id: I64d7c310dfa7ecf60eb1e59f094966520d473335
Reviewed-on: https://go-review.googlesource.com/7072Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>

Commit to stack copying for stack growth.

We're carrying around a surprising amount of cruft from older schemes.
I am confident that precise stack scans and stack copying are here to stay.

Delete fallback code for when precise stack info is disabled.
Delete fallback code for when copying stacks is disabled.
Delete fallback code for when StackCopyAlways is disabled.
Delete Stktop chain - there is only one stack segment now.
Delete M.moreargp, M.moreargsize, M.moreframesize, M.cret.
Delete G.writenbuf (unrelated, just dead).
Delete runtime.lessstack, runtime.oldstack.
Delete many amd64 morestack variants.
Delete initialization of morestack frame/arg sizes (shortens split prologue!).

Replace G's stackguard/stackbase/stack0/stacksize/
syscallstack/syscallguard/forkstackguard with simple stack
bounds (lo, hi).

Update liblink, runtime/cgo for adjustments to G.

LGTM=khr
R=khr, bradfitz
CC=golang-codereviews, iant, r
https://golang.org/cl/137410043

Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.

Both stdout and stderr are sent to /dev/null in android
apps. Introducing fatalf allows android to implement its
own copy that sends fatal errors to __android_log_print.

LGTM=minux, dave
R=minux, dave
CC=golang-codereviews
https://golang.org/cl/108400045

The runtime has historically held two dedicated values g (current goroutine)
and m (current thread) in 'extern register' slots (TLS on x86, real registers
backed by TLS on ARM).

This CL removes the extern register m; code now uses g->m.

On ARM, this frees up the register that formerly held m (R9).
This is important for NaCl, because NaCl ARM code cannot use R9 at all.

The Go 1 macrobenchmarks (those with per-op times >= 10 µs) are unaffected:

BenchmarkBinaryTree17              5491374955     5471024381     -0.37%
BenchmarkFannkuch11                4357101311     4275174828     -1.88%
BenchmarkGobDecode                 11029957       11364184       +3.03%
BenchmarkGobEncode                 6852205        6784822        -0.98%
BenchmarkGzip                      650795967      650152275      -0.10%
BenchmarkGunzip                    140962363      141041670      +0.06%
BenchmarkHTTPClientServer          71581          73081          +2.10%
BenchmarkJSONEncode                31928079       31913356       -0.05%
BenchmarkJSONDecode                117470065      113689916      -3.22%
BenchmarkMandelbrot200             6008923        5998712        -0.17%
BenchmarkGoParse                   6310917        6327487        +0.26%
BenchmarkRegexpMatchMedium_1K      114568         114763         +0.17%
BenchmarkRegexpMatchHard_1K        168977         169244         +0.16%
BenchmarkRevcomp                   935294971      914060918      -2.27%
BenchmarkTemplate                  145917123      148186096      +1.55%

Minux previous reported larger variations, but these were caused by
run-to-run noise, not repeatable slowdowns.

Actual code changes by Minux.
I only did the docs and the benchmarking.

LGTM=dvyukov, iant, minux
R=minux, josharian, iant, dave, bradfitz, dvyukov
CC=golang-codereviews
https://golang.org/cl/109050043

- do not lose profiling signals when we have no mcache (possible for syscalls/cgo)
- do not lose any profiling signals on windows
- fix profiling of cgo programs on windows (they had no m->thread setup)
- properly setup tls in cgo programs on windows
- check _beginthread return value

Fixes #6417.
Fixes #6986.

R=alex.brainman, rsc
CC=golang-codereviews
https://golang.org/cl/44820047

The naming in this package is a disaster.
Make it all consistent.

Remove some 'static' from functions that will
be referred to from other files soon.

This CL is purely renames using global search and replace.

Submitting separately so that real changes will not
be drowned out by these renames in future CLs.

TBR=iant
CC=golang-dev
https://golang.org/cl/7416046

Otherwise some OS X toolchains complain about the redeclaration
of libcgo_thread_start by multiple object files.  The real definition
is in util.c.

Fixes #2167.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5364045

This is a second attempt at submitting
https://golang.org/cl/3420043

A Mercurial problem lost the new files
in that submit.

TBR=r
CC=golang-dev
https://golang.org/cl/3511043

Returns R14 and R15 to the available register pool.
Plays more nicely with ELF ABI C code.
In particular, our signal handlers will no longer crash
when a signal arrives during execution of a cgo C call.

Fixes #720.

R=ken2, r
CC=golang-dev
https://golang.org/cl/1847051

better mach binaries.
cgo working on darwin+linux amd64+386.
eliminated context switches - pi is 30x faster.
add libcgo to build.

on snow leopard:
  - non-cgo binaries work; all tests pass.
  - cgo binaries work on amd64 but not 386.

R=r
DELTA=2031  (1316 added, 626 deleted, 89 changed)
OCL=35264
CL=35304