Updates #6046.
This CL just does maxstring and concatstring. There are other functions
to fix but doing them a few at a time will help isolate any (unlikely)
breakages these changes bring up in architectures I can't test
myself.

R=golang-dev, dave, iant
CC=golang-dev
https://golang.org/cl/12519044

I broke it with the darwin getwd attrlist stuff (0583e9d36dd).
plan9 doesn't have syscall.ENOTSUP.

It's in api/go1.txt as a symbol always available (not context-specific):

pkg syscall, const ENOTSUP Errno

... but plan9 isn't considered by cmd/api, so it only looks
universally available.  Alternatively, we could add a fake ENOTSUP
to plan9, but they were making efforts earlier to clean their
syscall package, so I'd prefer not to dump more in it.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12509044

This change replaces the hard-coded switch on compression method
in zipfile reader and writer with a map into which users can
register compressors and decompressors in their init()s.

R=golang-dev, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/12421043

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/12557043

NetBSD and OpenBSD are broken like OS X is. Good to know.

Drop required count from avg/2 to avg/3, because the
Plan 9 builder just barely missed avg/2 in one of its runs.

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/12548043

It turned out that change 12413043 did not break
any builders. So let's lock this in.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12545043

Looks like latest FreeBSD doesn't set address family identifer
for RTAX_NETMASK stuff; probably RTAX_GENMASK too, not confirmed.
This CL tries to identify address families by using the length of
each socket address if possible.

The issue is confirmed on FreeBSD 9.1.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12332043

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12508043

Unlike the existing net package own pollster, runtime-integrated
network pollster on BSD variants, actually kqueue, requires a socket
that has beed passed to syscall.Listen previously for a stream
listener.

This CL separates pollDesc.Init (actually runtime_pollOpen) from newFD
to allow control of each state of sockets and adds init method to netFD
instead. Upcoming CLs will rearrange the call order of runtime-integrated
pollster and syscall functions like the following;

- For dialers that open active connections, runtime_pollOpen will be
  called in between syscall.Bind and syscall.Connect.

- For stream listeners that open passive stream connections,
  runtime_pollOpen will be called just after syscall.Listen.

- For datagram listeners that open datagram connections,
  runtime_pollOpen will be called just after syscall.Bind.

This is in preparation for runtime-integrated network pollster for BSD
variants.

Update #5199

R=dvyukov, alex.brainman, minux.ma
CC=golang-dev
https://golang.org/cl/8608044

The current failures were:

fatal error: runtime: stack split during syscall
goroutine 1 [stack split]:
runtime.findnull(0x105a9080)
        /usr/go/src/pkg/runtime/string.goc:14 fp=0x305aefb8
runtime: unexpected return pc for runtime.errstr called from 0x80
runtime.errstr()
        /usr/go/src/pkg/runtime/sys_plan9_386.s:196 +0x2f fp=0x305aefc8

fatal error: runtime: stack split during syscall
goroutine 2 [stack split]:
runtime.nanotime(0x305bff3c)
        /usr/go/src/pkg/runtime/time_plan9_386.c:9 fp=0x305bff34
notetsleep(0x305bff9c, 0xf8475800, 0xd, 0x0, 0x0, ...)
        /usr/go/src/pkg/runtime/lock_sema.c:195 +0x87 fp=0x305bff48
runtime.notetsleepg(0x305bff9c, 0xf8475800, 0xd)
        /usr/go/src/pkg/runtime/lock_sema.c:266 +0xa4 fp=0x305bff68
runtime.MHeap_Scavenger()
        /usr/go/src/pkg/runtime/mheap.c:463 +0xc2 fp=0x305bffd0
runtime.goexit()
        /usr/go/src/pkg/runtime/proc.c:1332 fp=0x305bffd4
created by runtime.main
        /usr/go/src/pkg/runtime/proc.c:168

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12128043

On 10.6, OS X's fcntl returns EBADF instead of EINVAL.

R=golang-dev, iant, dave
CC=golang-dev
https://golang.org/cl/12493043

Update #6046.
This CL just does findnull and findnullw. There are other functions
to fix but doing them a few at a time will help isolate any (unlikely)
breakages these changes bring up in architectures I can't test
myself.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/12520043

R=alex.brainman
CC=golang-dev
https://golang.org/cl/12502044

Embed all data necessary for read/write operations directly into netFD.

benchmark                    old ns/op    new ns/op    delta
BenchmarkTCP4Persistent          27669        23341  -15.64%
BenchmarkTCP4Persistent-2        18173        12558  -30.90%
BenchmarkTCP4Persistent-4        10390         7319  -29.56%

This change will intentionally break all builders to see
how many allocations they do per read/write.
This will be fixed soon afterwards.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/12413043

gcpc/gcsp are used by GC in similar situation.
gcpc/gcsp are also more stable than gp->sched,
because gp->sched is mutated by entersyscall/exitsyscall
in morestack and mcall. So it has higher chances of being inconsistent.
Also, rename gcpc/gcsp to syscallpc/syscallsp.

This is the same as reverted change 12250043
with save marked as textflag 7.
The problem was that if save calls morestack,
then subsequent lessstack spoils g->sched.pc/sp.
And that bad values were remembered in g->syscallpc/sp.
Entersyscallblock had the same problem,
but it was never triggered to date.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12478043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12403043

Basically a partial rollback of 12053043 until I can
figure out what is really going on.
Fixes bug 6051.

R=golang-dev
CC=golang-dev
https://golang.org/cl/12496043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12490043

This means that pprof will no longer report profiles on OS X.
That's unfortunate, but the profiles were often wrong and, worse,
it was difficult to tell whether the profile was wrong or not.

The workarounds were making the scheduler more complex,
possibly caused a deadlock (see issue 5519), and did not actually
deliver reliable results.

It may be possible for adventurous users to apply a patch to
their kernels to get working results, or perhaps having no results
will encourage someone to do the work of creating a profiling
thread like on Windows. Issue 6047 has details.

Fixes #5519.
Fixes #6047.

R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/12429045

Uglier.

««« original CL description
all: use strings.IndexByte instead of Index where possible

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/12486043
»»»

R=golang-dev
CC=golang-dev
https://golang.org/cl/12485044

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/12486043

Fixes #5372.
Fixes #5577.

R=gri, rsc, bradfitz, r
CC=golang-dev
https://golang.org/cl/12265043

This means that in the common case (modern kernel), we only
make 1 system call to dup instead of two, and we also avoid
grabbing the syscall.ForkLock.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/12476043

you do reflect.call with too big an argument list.
Not worth the hassle.

Fixes #6023
Fixes #6033

R=golang-dev, bradfitz, dave
CC=golang-dev
https://golang.org/cl/12485043

Fixes #3751

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/12483043

Fixes #4963.

Sets the append crossover to 0 on intel platforms.

Results for linux/amd64 Core i5 SNB

benchmark                     old ns/op    new ns/op    delta
BenchmarkAppend                     102          104   +1.96%
BenchmarkAppend1Byte                 10           11   +0.92%
BenchmarkAppend4Bytes                15           11  -28.10%
BenchmarkAppend7Bytes                17           12  -32.58%
BenchmarkAppend8Bytes                18           12  -36.17%
BenchmarkAppend15Bytes               24           11  -55.02%
BenchmarkAppend16Bytes               25           11  -56.03%
BenchmarkAppend32Bytes               11           12   +4.31%
BenchmarkAppendStr1Byte               8            9  +13.99%
BenchmarkAppendStr4Bytes             11            9  -17.52%
BenchmarkAppendStr8Bytes             14            9  -35.70%
BenchmarkAppendStr16Bytes            21            9  -55.19%
BenchmarkAppendStr32Bytes            10           10   -5.66%
BenchmarkAppendSpecialCase           49           52   +7.96%

Results for linux/386 Atom(TM) CPU 330 @ 1.60GHz

benchmark                     old ns/op    new ns/op    delta
BenchmarkAppend                     219          218   -0.46%
BenchmarkAppend1Byte                 75           72   -3.44%
BenchmarkAppend4Bytes                92           73  -19.87%
BenchmarkAppend7Bytes               108           74  -31.20%
BenchmarkAppend8Bytes               116           74  -35.95%
BenchmarkAppend15Bytes              162           77  -52.22%
BenchmarkAppend16Bytes              169           77  -54.20%
BenchmarkAppend32Bytes               88           86   -2.38%
BenchmarkAppendStr1Byte              57           59   +3.32%
BenchmarkAppendStr4Bytes             72           59  -17.40%
BenchmarkAppendStr8Bytes             92           60  -34.70%
BenchmarkAppendStr16Bytes           141           63  -54.89%
BenchmarkAppendStr32Bytes            75           73   -2.64%
BenchmarkAppendSpecialCase          270          270   +0.00%

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12440044

For normal slices a[i:j] we're generating 3 bounds
checks: j<={len(string),cap(slice)}, j<=j (!), and i<=j.
Somehow snuck in as part of the [i:j:k] implementation
where the second check does something.
Remove the second check when we don't need it.

R=rsc, r
CC=golang-dev
https://golang.org/cl/12311046

Update #5910.

R=golang-dev, daniel.morsing, rsc
CC=golang-dev
https://golang.org/cl/11373044

While we're here, add a test for the same functionality in gzip,
which was already implemented, and add bzip2 CRC checks.

Fixes #5772.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12387044

It's still easy to turn off, but the builders are happy.
Also document.

R=golang-dev, iant, dvyukov
CC=golang-dev
https://golang.org/cl/12371043

Break all 386 builders.

««« original CL description
runtime: use gcpc/gcsp during traceback of goroutines in syscalls
gcpc/gcsp are used by GC in similar situation.
gcpc/gcsp are also more stable than gp->sched,
because gp->sched is mutated by entersyscall/exitsyscall
in morestack and mcall. So it has higher chances of being inconsistent.
Also, rename gcpc/gcsp to syscallpc/syscallsp.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12250043
»»»

R=rsc
CC=golang-dev
https://golang.org/cl/12424045

Fixes #4807

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12349044

It was needed for the old scheduler,
because there temporary could be more threads than gomaxprocs.
In the new scheduler gomaxprocs is always respected.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12438043

gcpc/gcsp are used by GC in similar situation.
gcpc/gcsp are also more stable than gp->sched,
because gp->sched is mutated by entersyscall/exitsyscall
in morestack and mcall. So it has higher chances of being inconsistent.
Also, rename gcpc/gcsp to syscallpc/syscallsp.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12250043

GCM is Galois Counter Mode, an authenticated encryption mode that is,
nearly always, used with AES.

R=rsc
CC=golang-dev
https://golang.org/cl/12375043

In the event that code tries to use a hash function that isn't compiled
in and panics, give the developer a fighting chance of figuring out
which hash function it needed.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12420045

Fixes #6045.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12463043

Fixes #6025.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/12387046

Fixes #5785.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/10587043

Fixes #6003.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12387045