Debugging the Windows breakage I noticed that SEH
only exists on 386, so we can balance the two stacks
a little more on amd64 and reclaim another word.

Now we're down to just one word consumed by
cgocallback_gofunc, having reclaimed 25% of the
overall budget (4 words out of 16).

Separately, fix windows/386 - the SEH must be on the
m0 stack, as must the saved SP, so we are forced to have
a three-word frame for 386. It matters much less for
386, because there 128 bytes gives 32 words to use.

R=dvyukov, alex.brainman
CC=golang-dev
https://golang.org/cl/11551044

R=dvyukov, r
CC=golang-dev
https://golang.org/cl/11761043

TBR=golang-dev
CC=golang-dev
https://golang.org/cl/11595045

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/11492045

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/11745044

The existing function, IsOneOf, is hard to use. Since the slice comes
before the rune, in parallelism with the other Is functions, the slice
is clumsy to build. This CL adds a nicer-signatured In function of
equivalent functionality (its implementation is identical) that's much
easier to use. Compare:
        unicode.IsOneOf([]*unicode.RangeTable{unicode.Letter, unicode.Number}, r)
        unicode.In(r, unicode.Letter, unicode.Number)

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/11672044

Also adds maxListenerBacklog placeholder for Plan 9.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11674044

Tying preemption to stack splits means that we have to able to
complete the call to exitsyscall (inside cgocallbackg at least for now)
without any stack split checks, meaning that the whole sequence
has to work within 128 bytes of stack, unless we increase the size
of the red zone. This CL frees up 24 bytes along that critical path
on amd64. (The 32-bit systems have plenty of space because all
their words are smaller.)

R=dvyukov
CC=golang-dev
https://golang.org/cl/11676043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/11709043

This would have failed with CL 11663043.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11480045

Fixes #5937.

R=golang-dev, mirtchovski, r
CC=golang-dev
https://golang.org/cl/11705043

When making an HTTPS client request, respect the
ServerName field in the tls.Config.

Fixes #5829

R=golang-dev, agl, adg
CC=golang-dev
https://golang.org/cl/11691043

Fixes #5936

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11620046

Phrases like "returns whether or not the image is opaque" could be
describing what the function does (it always returns, regardless of
the opacity) or what it returns (a boolean indicating the opacity).
Even when the "or not" is missing, the phrasing is bizarre.

Go with "reports whether", which is still clunky but at least makes
it clear we're talking about the return value.

These were edited by hand. A few were cleaned up in other ways.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/11699043

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11691044

Change use of x+(SP) to access the stack frame into x-(SP)

Fixes #5925.

R=golang-dev, bradfitz, dave, remyoudompheng, nick, rsc
CC=dave cheney <dave, golang-dev
https://golang.org/cl/11647043

For consistency with Go documentation style.

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/11697043

src/cmd/ld/lib.c:1379 set and not used: p
src/cmd/ld/lib.c:1426 format mismatch 6llux INT, arg 3
src/cmd/ld/lib.c:1437 format mismatch 6llux INT, arg 3
src/cmd/ld/lib.c:1456 format mismatch 6llux INT, arg 3
src/cmd/ld/lib.c:1477 format mismatch 6llux INT, arg 3
src/cmd/ld/lib.c:1459 set and not used: started

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/11615044

notetsleepg is the same as notetsleep, but is called on user g.
It includes entersyscall/exitsyscall and will help to avoid
split stack functions in syscall status.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/11681043

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11677043

This gives more space during the call to runtime.lock.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/11679043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/11671043

R=dave
CC=golang-dev
https://golang.org/cl/11537044

Moves the network poller from net package into runtime.

benchmark                           old ns/op    new ns/op    delta
BenchmarkTCP4OneShot                   316386       287061   -9.27%
BenchmarkTCP4OneShot-2                 339822       313424   -7.77%
BenchmarkTCP4OneShot-3                 330057       306589   -7.11%
BenchmarkTCP4OneShotTimeout            341775       287061  -16.01%
BenchmarkTCP4OneShotTimeout-2          380835       295849  -22.32%
BenchmarkTCP4OneShotTimeout-3          398412       328070  -17.66%
BenchmarkTCP4Persistent                 40622        33392  -17.80%
BenchmarkTCP4Persistent-2               44528        35736  -19.74%
BenchmarkTCP4Persistent-3               44919        36907  -17.84%
BenchmarkTCP4PersistentTimeout          45309        33588  -25.87%
BenchmarkTCP4PersistentTimeout-2        50289        38079  -24.28%
BenchmarkTCP4PersistentTimeout-3        51559        37103  -28.04%
BenchmarkTCP6OneShot                   361305       345645   -4.33%
BenchmarkTCP6OneShot-2                 361305       331976   -8.12%
BenchmarkTCP6OneShot-3                 376929       347598   -7.78%
BenchmarkTCP6OneShotTimeout            361305       322212  -10.82%
BenchmarkTCP6OneShotTimeout-2          378882       333928  -11.86%
BenchmarkTCP6OneShotTimeout-3          388647       335881  -13.58%
BenchmarkTCP6Persistent                 47653        35345  -25.83%
BenchmarkTCP6Persistent-2               49215        35736  -27.39%
BenchmarkTCP6Persistent-3               38474        37493   -2.55%
BenchmarkTCP6PersistentTimeout          56637        34369  -39.32%
BenchmarkTCP6PersistentTimeout-2        42575        38079  -10.56%
BenchmarkTCP6PersistentTimeout-3        44137        37689  -14.61%

R=dvyukov
CC=golang-dev
https://golang.org/cl/8670044

Trivial, but annoying while debugging this code.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11656043

Fixes #5898.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/11556043

Calls into math/rand are very slow, especially under race
detector because of heap accesses.

go test -bench . -run none -benchtime .1s
Before: 23.0s
After:  17.4s

Fixes #5837.

R=golang-dev, dave, r
CC=golang-dev
https://golang.org/cl/11564044

R=golang-dev, dave, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/10030043

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11623043

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/11620044

This does not change the default compiler on OS X to clang.
It appears that for now we can keep using gcc as long as we
enable a few more warning settings that are on-by-default
elsewhere.

R=golang-dev, bradfitz, dave
CC=golang-dev
https://golang.org/cl/11610044

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/11604043

Fixes #5924.

R=golang-dev, khr, rsc
CC=golang-dev
https://golang.org/cl/11606043

This CL introduces a FUNCDATA number for runtime-specific
garbage collection metadata, changes the C and Go compilers
to emit that metadata, and changes the runtime to expect it.

The old pseudo-instructions that carried this information
are gone, as is the linker code to process them.

R=golang-dev, dvyukov, cshapiro
CC=golang-dev
https://golang.org/cl/11406044

So far no checked-in assembly needs these,
but it matches having them for M and G.
I needed these for some manual testing.

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/11595043

where it belongs.

R=rsc
CC=golang-dev
https://golang.org/cl/11596043

whose argument size is unknown (C vararg functions, and
assembly code without an explicit specification).

We used to use 0 to mean "unknown" and 1 to mean "zero".
Now we use ArgsSizeUnknown (0x80000000) to mean "unknown".

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/11590043

This holds the last finalized object and arguments to its finalizer.
Fixes #5348.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/11454044

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/11432046

It contains pointers to first blocks of lots of spans.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/11416046