Fixes #5061.

Current code relies on the fact that fd's are automatically removed from epoll set when closed. However, it is not true. Underlying file description is removed from epoll set only when *all* fd's referring to it are closed.

There are 2 bad consequences:
1. Kernel delivers notifications on already closed fd's.
2. The following sequence of events leads to error:
   - add fd1 to epoll
   - dup fd1 = fd2
   - close fd1 (not removed from epoll since we've dup'ed the fd)
   - dup fd2 = fd1 (get the same fd as fd1)
   - add fd1 to epoll = EEXIST

So, if fd can be potentially dup'ed of fork'ed, it's necessary to explicitly remove the fd from epoll set.

R=golang-dev, bradfitz, dave
CC=golang-dev
https://golang.org/cl/7870043

Use per-thread work buffers instead of global mutex-protected pool. This eliminates contention from parallel scan phase.

benchmark                             old ns/op    new ns/op    delta
garbage.BenchmarkTree2-8               97100768     71417553  -26.45%
garbage.BenchmarkTree2LastPause-8     970931485    714103692  -26.45%
garbage.BenchmarkTree2Pause-8         469127802    345029253  -26.45%
garbage.BenchmarkParser-8            2880950854   2715456901   -5.74%
garbage.BenchmarkParserLastPause-8    137047399    103336476  -24.60%
garbage.BenchmarkParserPause-8         80686028     58922680  -26.97%

R=golang-dev, 0xe2.0x9a.0x9b, dave, adg, rsc, iant
CC=golang-dev
https://golang.org/cl/7816044

Add missing CLOSUREVAR in switch.
Mark MAKE, string conversion nodes as impossible.
Control statements do not need instrumentation.
Instrument COM and LROT nodes.
Instrument map length.

Update #4228

R=dvyukov, golang-dev
CC=golang-dev
https://golang.org/cl/7504047

Currently fails with a compiler error, though.

R=golang-dev, agl, rsc
CC=golang-dev
https://golang.org/cl/7933043

R=ken2
CC=golang-dev
https://golang.org/cl/7518050

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7936043

R=rsc, bradfitz, khr
CC=golang-dev
https://golang.org/cl/7849047

The analysis does not depend on the values of the items.
Fixes #4648.

R=golang-dev, gri, rsc
CC=golang-dev
https://golang.org/cl/7593050

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7858045

R=rsc, minux.ma, khr
CC=golang-dev
https://golang.org/cl/7763050

TBR=dvyukov
CC=golang-dev
https://golang.org/cl/7635046

Fixes #5089.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7767044

R=ken2, ken
CC=golang-dev
https://golang.org/cl/7546052

Fixes #2280.

R=golang-dev, r, bradfitz, iant, andybalholm, gri
CC=golang-dev
https://golang.org/cl/7816045

Hashtable is arranged as an array of
8-entry buckets with chained overflow.
Each bucket has 8 extra hash bits
per key to provide quick lookup within
a bucket.  Table is grown incrementally.

Update #3885
Go time drops from 0.51s to 0.34s.

R=r, rsc, m3b, dave, bradfitz, khr, ugorji, remyoudompheng
CC=golang-dev
https://golang.org/cl/7504044

Fixes #5074 in multi-threaded scenarios.

R=golang-dev, daniel.morsing, dave, dvyukov, bradfitz, rsc
CC=golang-dev, remyoudompheng
https://golang.org/cl/7916043

Found this inconsistency from net/http's Server while
debugging Issue 4183

Unfortunately this package lacks testing around this,
or most of child.go. :/

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7735046

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7786046

Fixes #5085.

{6,8}c/swt.c allocates a third Biobuf in automatic memory which is not terminated at the end of the function. This causes the buffer to be 'in use' when the batexit handler fires, confusing valgrind.

Huge thanks to DMorsing for the diagnosis.

R=golang-dev, daniel.morsing, rsc
CC=golang-dev
https://golang.org/cl/7844044

Fixes cgo builds.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/7784044

No net package involved. And with ReportAllocs we can see
how much garbage is created per request.

R=adg, dave
CC=golang-dev
https://golang.org/cl/7913044

Fixes build. One part of ../misc/cgo/test appears to be unhappy but this does not cause the build to fail.

R=rsc, r
CC=golang-dev
https://golang.org/cl/7769047

R=golang-dev, rsc, dave
CC=golang-dev
https://golang.org/cl/7914043

R=rsc, daniel.morsing
CC=golang-dev
https://golang.org/cl/7613046

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/7856048

Inserting a key-value pair into a hashmap storing keys or values
indirectly can cause the garbage collector to find the hashmap in
an inconsistent	state.

Fixes #5074.

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/7913043

R=rsc
CC=golang-dev
https://golang.org/cl/7662045

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/7552045

While we're here, downgrade DWARF to version 2.
We're not using any version 3 features, and OS X gdb
only supports version 2.

Fixes #3436.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/7891044

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7909043

Still disabled. Need to fix TLS.

R=golang-dev, minux.ma, bradfitz
CC=golang-dev
https://golang.org/cl/7783044

R=golang-dev, rsc
CC=dvyukov, golang-dev
https://golang.org/cl/7879043

R=golang-dev, dvyukov, rsc
CC=golang-dev
https://golang.org/cl/7473044

R=golang-dev, r, rsc
CC=golang-dev
https://golang.org/cl/7869043

- A note doesn't have to be in the first
comment of a comment group anymore, and
several notes may appear in the same comment
group (e.g., it is fairly common to have a
TODO(uid) note immediately following another
comment).

- Define a doc.Note type which also contains
note uid and position info.

- Better formatting in godoc output. The position
information is not yet used, but could be used to
locate the note in the source text if desired.

Fixes #4843.

R=r, cnicolaou
CC=gobot, golang-dev
https://golang.org/cl/7496048

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7856044

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7884045

Also applies camel style to test case holders.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7884043

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7554051

godef[1][2] is a third party tool for printing information about
expressions, especially the location of their definition. This can be
used to implement a "jump to definition" function. Unlike
cross-language solutions like ctags, godef does not require an index,
operates on the Go AST instead of symbols and works across packages,
including the standard library.

This patch implements two new public functions: godef-describe (C-c
C-d) and godef-jump (C-d C-j). godef-describe describes the expression
at point, printing its type, and godef-jump jumps to its definition.

[1]: https://code.google.com/p/rog-go/source/browse/exp/cmd/godef/
[2]: go get code.google.com/p/rog-go/exp/cmd/godef

R=adonovan, cw, patrick.allen.higgins, sameer
CC=golang-dev
https://golang.org/cl/7781043