Enable cgo on OpenBSD.

The OpenBSD ld.so(1) does not currently support PT_TLS sections. Work
around this by fixing up the TCB that has been provided by librthread
and reallocating a TCB with additional space for TLS. Also provide a
wrapper for pthread_create, allowing zeroed TLS to be allocated for
threads created externally to Go.

Joint work with Shenghou Ma (minux).

Requires change 6846064.

Fixes #3205.

R=golang-dev, minux.ma, iant, rsc, iant
CC=golang-dev
https://golang.org/cl/6853059

The OpenBSD ld.so(1) does not currently support PT_TLS and refuses
to load ELF binaries that contain PT_TLS sections. Do not emit PT_TLS
sections - we will handle this appropriately in runtime/cgo instead.

R=golang-dev, minux.ma, iant
CC=golang-dev
https://golang.org/cl/6846064

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6968049

Fixes #4550.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6973048

If a handler did a panic(nil), the connection was never closed.

Fixes #4050

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6971049

Fixes #4345.

Benchmarks are promising,

benchmark         old ns/op    new ns/op    delta
BenchmarkPrint     14716391     14747131   +0.21%

benchmark         old ns/op    new ns/op    delta
BenchmarkParse      8846219      8809343   -0.42%

benchmark          old MB/s     new MB/s  speedup
BenchmarkParse         6.61         6.64    1.00x

Also includes additional tests to improve token.FileSet coverage.

R=dvyukov, gri
CC=golang-dev
https://golang.org/cl/6968044

Update #4354.

Add a test to expose the race in the FileSet position cache.

R=dvyukov, gri
CC=fullung, golang-dev
https://golang.org/cl/6940078

R=golang-dev, agl, iant
CC=golang-dev
https://golang.org/cl/6955043

caught by https://github.com/lyda/misspell-check.

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/6949072

cmd/go: pass gccgoflags at the end of gccgo command line, warn if user passes the wrong toolchain options

R=iant
CC=golang-dev
https://golang.org/cl/6940082

runtime: use "mp" and "gp" instead of "m" and "g" for local variable name to avoid confusion with the global "m" and "g".

R=golang-dev, minux.ma, rsc
CC=bradfitz, golang-dev
https://golang.org/cl/6939064

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/6945079

For CL 6853059.

R=jsing, rsc
CC=golang-dev
https://golang.org/cl/6938076

For Linux/{386,arm}, FreeBSD/{386,amd64,arm}, NetBSD/{386,amd64}, OpenBSD/{386,amd64}.
Note: our Darwin implementation already has ns resolution.

Linux/386 (Core i7-2600 @ 3.40GHz, kernel 3.5.2-gentoo)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow          110          118   +7.27%

Linux/ARM (ARM Cortex-A8 @ 800MHz, kernel 2.6.32.28 android)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow          625          542  -13.28%

Linux/ARM (ARM Cortex-A9 @ 1GHz, Pandaboard)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow          992          909   -8.37%

FreeBSD 9-REL-p1/amd64 (Dell R610 Server with Xeon X5650 @ 2.67GHz)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow          699          695   -0.57%

FreeBSD 9-REL-p1/amd64 (Atom D525 @ 1.80GHz)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow         1553         1658   +6.76%

OpenBSD/amd64 (Dell E6410 with i5 CPU M 540 @ 2.53GHz)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow         1262         1236   -2.06%

OpenBSD/i386 (Asus eeePC 701 with Intel Celeron M 900MHz - locked to 631MHz)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow         5089         5043   -0.90%

NetBSD/i386 (VMware VM with Core i5 CPU @ 2.7GHz)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow          277          278   +0.36%

NetBSD/amd64 (VMware VM with Core i5 CPU @ 2.7Ghz)
benchmark       old ns/op    new ns/op    delta
BenchmarkNow          103          105   +1.94%

Thanks Maxim Khitrov, Joel Sing, and Dave Cheney for providing benchmark data.

R=jsing, dave, rsc
CC=golang-dev
https://golang.org/cl/6820120

R=golang-dev, bradfitz, gri
CC=golang-dev
https://golang.org/cl/6935071

R=rsc, alex.brainman
CC=golang-dev
https://golang.org/cl/6948066

Fixes #4518.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6932045

Fixes #4481.

hello-world-core.gz was generated with a simple hello world c program and core dumped as suggested in the issue.

Also: add support for gz compressed test fixtures.

R=minux.ma, rsc, iant
CC=golang-dev
https://golang.org/cl/6936058

Fixes #4502.

R=rsc
CC=golang-dev
https://golang.org/cl/6949058

Fixes #4531

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6937069

Details:
- fixed variadic parameter passing and calls of the form f(g())
- fixed implementation of ^x for unsigned constants x
- fixed assignability of untyped booleans
- resolved a few TODOs, various minor fixes
- enabled many more tests (only 6 std packages don't typecheck)

R=rsc
CC=golang-dev
https://golang.org/cl/6930053

This is expensive but it might be useful in cases where
people are suffering from false positives during garbage
collection and are willing to trade the CPU time for getting
rid of the false positives.

On the other hand it only eliminates false positives caused
by other function calls, not false positives caused by dead
temporaries stored in the current function call.

The 5g/6g/8g changes were pulled out of the history, from
the last time we needed to do this (to work around a goto bug).
The code in go.h, lex.c, pgen.c is new but tiny.

R=ken2
CC=golang-dev
https://golang.org/cl/6938073

reader.Read() can return both 0,nil and len(buf),err.
To be safe, we use io.ReadFull instead of doing reader.Read directly.

Fixes #3472.

R=bradfitz, rsc, ality
CC=golang-dev
https://golang.org/cl/6285050

This decreases the amount of system calls during the
first call to Getenv. Calling Environ will still read
in all environment variables and populate the cache.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6939048

Fixes #3729.

R=rsc
CC=golang-dev
https://golang.org/cl/6938052

With this change the runtime can now read GOMAXPROCS, GOGC, etc.

I'm not quite sure how we missed this.

R=seed, lucio.dere, rsc
CC=golang-dev
https://golang.org/cl/6935062

Update #4555.

R=gri, iant
CC=golang-dev
https://golang.org/cl/6944059

A data race was found in TestSendMail by the race detector.

Fixes #4559.

R=golang-dev, bradfitz, dave, rsc
CC=golang-dev
https://golang.org/cl/6944057

there is no concept of “undefined” variables for Expand。

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6946063

Fixes #4548.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6944053

R=golang-dev, rsc, bradfitz
CC=golang-dev
https://golang.org/cl/6935061

Fixes #4051

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6943063

The code:
func main() {
        v := make([]int64, 10)
        i := 1
        _ = v[(i*4)/3]
}
crashes compiler with:

Program received signal SIGSEGV, Segmentation fault.
0x000000000043c274 in walkexpr (np=0x7fffffffc9b8, init=0x0) at src/cmd/gc/walk.c:587
587			*init = concat(*init, n->ninit);
(gdb) bt
#0  0x000000000043c274 in walkexpr (np=0x7fffffffc9b8, init=0x0) at src/cmd/gc/walk.c:587
#1  0x0000000000432d15 in copyexpr (n=0x7ffff7f69a48, t=<optimized out>, init=0x0) at src/cmd/gc/subr.c:2020
#2  0x000000000043f281 in walkdiv (init=0x0, np=0x7fffffffca70) at src/cmd/gc/walk.c:2901
#3  walkexpr (np=0x7ffff7f69760, init=0x0) at src/cmd/gc/walk.c:956
#4  0x000000000043d801 in walkexpr (np=0x7ffff7f69bc0, init=0x0) at src/cmd/gc/walk.c:988
#5  0x000000000043cc9b in walkexpr (np=0x7ffff7f69d38, init=0x0) at src/cmd/gc/walk.c:1068
#6  0x000000000043c50b in walkexpr (np=0x7ffff7f69f50, init=0x0) at src/cmd/gc/walk.c:879
#7  0x000000000043c50b in walkexpr (np=0x7ffff7f6a0c8, init=0x0) at src/cmd/gc/walk.c:879
#8  0x0000000000440a53 in walkexprlist (l=0x7ffff7f6a0c8, init=0x0) at src/cmd/gc/walk.c:357
#9  0x000000000043d0bf in walkexpr (np=0x7fffffffd318, init=0x0) at src/cmd/gc/walk.c:566
#10 0x00000000004402bf in vmkcall (fn=<optimized out>, t=0x0, init=0x0, va=0x7fffffffd368) at src/cmd/gc/walk.c:2275
#11 0x000000000044059a in mkcall (name=<optimized out>, t=0x0, init=0x0) at src/cmd/gc/walk.c:2287
#12 0x000000000042862b in callinstr (np=0x7fffffffd4c8, init=0x7fffffffd568, wr=0, skip=<optimized out>) at src/cmd/gc/racewalk.c:478
#13 0x00000000004288b7 in racewalknode (np=0x7ffff7f68108, init=0x7fffffffd568, wr=0, skip=0) at src/cmd/gc/racewalk.c:287
#14 0x0000000000428781 in racewalknode (np=0x7ffff7f65840, init=0x7fffffffd568, wr=0, skip=0) at src/cmd/gc/racewalk.c:302
#15 0x0000000000428abd in racewalklist (l=0x7ffff7f65840, init=0x0) at src/cmd/gc/racewalk.c:97
#16 0x0000000000428d0b in racewalk (fn=0x7ffff7f5f010) at src/cmd/gc/racewalk.c:63
#17 0x0000000000402b9c in compile (fn=0x7ffff7f5f010) at src/cmd/6g/../gc/pgen.c:67
#18 0x0000000000419f86 in funccompile (n=0x7ffff7f5f010, isclosure=0) at src/cmd/gc/dcl.c:1414
#19 0x0000000000424161 in p9main (argc=<optimized out>, argv=<optimized out>) at src/cmd/gc/lex.c:431
#20 0x0000000000401739 in main (argc=<optimized out>, argv=<optimized out>) at src/lib9/main.c:35

The problem is nil init passed to mkcall().

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6940045

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/6937065

Those variables come from ancient times when reflect.Value was
an interface.

R=dave, rsc
CC=golang-dev
https://golang.org/cl/6946059

Add a Hello method that allows clients to set the server sent in the EHLO/HELO exchange; the default remains localhost.
Based on CL 5555045 by rsc.

Fixes #4219.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6946057

Details:

- This CL is the conceptual skeleton of code found in CL 6114046

- The garbage collector uses struct Obj to specify memory blocks

- scanblock() is putting found memory blocks into an intermediate buffer
  (xbuf) before adding/flushing them to the main work buffer (wbuf)

- The main loop in scanblock() is replaced with a skeleton code that
  in the future will be able to recognize the type of objects and
  thus will improve the garbage collector's precision.
  For now, all objects are simply sequences of pointers so
  the precision of the garbage collector remains unchanged.

- The code plugs .gcdata and .gcbss sections into the garbage collector.
  scanblock() in this CL is unable to make any use of this.

R=rsc, dvyukov, remyoudompheng
CC=dave, golang-dev, minux.ma
https://golang.org/cl/6856121

Fixes #4499.

R=rsc
CC=golang-dev
https://golang.org/cl/6931046

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/6947067

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/6951043