Fixes #4040.

R=rsc
CC=golang-dev
https://golang.org/cl/6497098

Broke tests on 386.

««« original CL description
6l/8l: emit correct opcodes to F(SUB|DIV)R?D.

When the destination was not F0, 6l and 8l swapped FSUBD/FSUBRD and
FDIVD/FDIVRD.

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6498092
»»»

R=golang-dev
CC=golang-dev
https://golang.org/cl/6492100

When the destination was not F0, 6l and 8l swapped FSUBD/FSUBRD and
FDIVD/FDIVRD.

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6498092

Also, clear Content-Type and Content-Length on Not Modified
responses before server.go strips them and spams the logs with
warnings.

R=rsc
CC=golang-dev
https://golang.org/cl/6503090

No longer necessary after https://golang.org/cl/6497073/
removed the `if(n5.op != OXXX) { regfree(&n5); }`.

R=remy, r
CC=golang-dev, rsc
https://golang.org/cl/6498101

R=golang-dev
CC=golang-dev
https://golang.org/cl/6497106

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/6496099

This makes the compilers code more similar and improves
code generation a lot.

The number of LEAL instructions generated for cmd/go drops
by 60%.

% GOARCH=386 go build -gcflags -S -a cmd/go | grep LEAL | wc -l
Before:       89774
After:        47548

benchmark                              old ns/op    new ns/op    delta
BenchmarkAppendFloatDecimal                  540          444  -17.78%
BenchmarkAppendFloat                        1160         1035  -10.78%
BenchmarkAppendFloatExp                     1060          922  -13.02%
BenchmarkAppendFloatNegExp                  1053          920  -12.63%
BenchmarkAppendFloatBig                     1773         1558  -12.13%
BenchmarkFormatInt                         13065        12481   -4.47%
BenchmarkAppendInt                         10981         9900   -9.84%
BenchmarkFormatUint                         3804         3650   -4.05%
BenchmarkAppendUint                         3506         3303   -5.79%
BenchmarkUnquoteEasy                         714          683   -4.34%
BenchmarkUnquoteHard                        5117         2915  -43.03%

Update #1914.

R=nigeltao, rsc, golang-dev
CC=golang-dev, remy
https://golang.org/cl/6489067

It might be meaningful, and stable than others.

R=golang-dev, agl
CC=golang-dev
https://golang.org/cl/6499091

Refactored build + buildTrie into build + buildOrdering.
Note that since the tailoring code is not checked in yet, all tailorings are identical
to root.  The table therefore should not and does not grow at this point.

R=r
CC=golang-dev
https://golang.org/cl/6500087

R=r
CC=golang-dev
https://golang.org/cl/6499079

R=r
CC=golang-dev
https://golang.org/cl/6493097

R=r
CC=golang-dev
https://golang.org/cl/6498106

R=golang-dev, 0xjnml, iant, adonovan, aram
CC=golang-dev
https://golang.org/cl/6500092

R=r
CC=golang-dev
https://golang.org/cl/6490095

Fixes #4052.

R=golang-dev, bradfitz, iant, rsc
CC=golang-dev
https://golang.org/cl/6490092

This test was previously removed in 087c6e15702e.

R=bradfitz, rsc, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/6506061

After further deliberation, let's back down to the Unicode proposal.
Ignoring aBOMinations anywhere means that things like
        grep unsafe *.go
might fail because there's a BOM in the middle: unBOMsafe.

R=golang-dev, rsc, 0xjnml, gri, bradfitz
CC=golang-dev
https://golang.org/cl/6490091

R=r
CC=dsymonds, gobot, golang-dev
https://golang.org/cl/6495085

Fixes #4037.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6488093

It's easier just to declare a new variable.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6501103

The main case where it happens is when evaluating &s[i] without
bounds checking, which usually happens during range loops (i=0).

This allows registerization of the corresponding variables,
saving 16 bytes of stack frame for each such range loop and a
LEAQ instruction.

R=golang-dev, rsc, dave
CC=golang-dev, remy
https://golang.org/cl/6497073

Fixes #3911.

Requires CL 6449127.

dfc@qnap:~$ ./runtime.test
runtime: this CPU has no floating point hardware, so it cannot run
this GOARM=7 binary. Recompile using GOARM=5.

R=rsc, minux.ma
CC=golang-dev
https://golang.org/cl/6442109

When generating enums use the debug data section instead of the
DWARF debug info, if it is available in the ELF file. This allows
mkerrors.sh to work correctly on OpenBSD/386 and NetBSD/386.

Fixes #2470.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/6495090

The parser depends on it but the client might not import it, so make sure it's there.
Fixes #4038.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6497094

Happy Birthday UTF-8.

R=golang-dev, rsc, 0xjnml
CC=golang-dev
https://golang.org/cl/6506083

Regenerate/update netbsd z-files on NetBSD 6.0 RC1.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6506062

Fixes #3862.

There were many areas where conn.err was being accessed
outside the mutex. This proposal moves the err value to
an embedded struct to make it more obvious when the error
value is being accessed.

As there are no Benchmark tests in this package I cannot
feel confident of the impact of this additional locking,
although most will be uncontended.

R=dvyukov, agl
CC=golang-dev
https://golang.org/cl/6497070

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/6493087

promised in CL 13985.

R=r
CC=golang-dev
https://golang.org/cl/6503071

order.

JPEG images generated prior to this CL are still valid JPEGs, as the
quantization tables used are encoded in the wire format. Such JPEGs just
don't use the recommended quantization tables.

R=r, dsymonds, raph, adg
CC=golang-dev, tuom.larsen
https://golang.org/cl/6497083

consistent with OLROT. Delete unused OBAD, OLRC.

R=rsc, dave
CC=golang-dev
https://golang.org/cl/6489082

The old code was a depth first graph traversal that could, under the
right conditions, end up re-exploring the same subgraphs multiple
times, once for each way to arrive at that subgraph at a given depth.

The new code uses a breadth first search to make sure that it only
visits each reachable embedded struct once.

Also add fast path for the trivial case.

benchmark                old ns/op    new ns/op    delta
BenchmarkFieldByName1         1321          187  -85.84%
BenchmarkFieldByName2         6118         5186  -15.23%
BenchmarkFieldByName3      8218553        42112  -99.49%

R=gri, r
CC=golang-dev
https://golang.org/cl/6458090

R=nigeltao
CC=golang-dev
https://golang.org/cl/6499075

R=dsymonds
CC=golang-dev
https://golang.org/cl/6503070

R=rsc, daniel.morsing
CC=golang-dev
https://golang.org/cl/6495074

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6490076

All of them call `newFileFD' which must properly restore close-on-exec on
duplicated fds.

R=golang-dev, bradfitz, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/6445081

Signal handlers are global resources but many language
environments (Go, C++ at Google, etc) assume they have sole
ownership of a particular handler.  Signal handlers in
mixed-language applications must therefore be robust against
unexpected delivery of certain signals, such as SIGPROF.

The default Go signal handler runtime·sigtramp assumes that it
will never be called on a non-Go thread, but this assumption
is violated by when linking in C++ code that spawns threads.
Specifically, the handler asserts the thread has an associated
"m" (Go scheduler).

This CL is a very simple workaround: discard SIGPROF delivered to non-Go threads.  runtime.badsignal(int32) now receives the signal number; if it returns without panicking (e.g. sig==SIGPROF) the signal is discarded.

I don't think there is any really satisfactory solution to the
problem of signal-based profiling in a mixed-language
application.  It's not only the issue of handler clobbering,
but also that a C++ SIGPROF handler called in a Go thread
can't unwind the Go stack (and vice versa).  The best we can
hope for is not crashing.

Note:
- I've ported this to all POSIX platforms, except ARM-linux which already ignores unexpected signals on m-less threads.
- I've avoided tail-calling runtime.badsignal because AFAICT the 6a/6l don't support it.
- I've avoided hoisting 'push sig' (common to both function calls) because it makes the code harder to read.
- Fixed an (apparently incorrect?) docstring.

R=iant, rsc, minux.ma
CC=golang-dev
https://golang.org/cl/6498057

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6489065