Fixes #5036.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7531045

Will help people find the rules by searching the spec by
having a comment saying "missing return";
"terminating statement" does not evoke the rule to the
uninitiated.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7838044

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7834046

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7973043

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7879044

The GIF89a spec says: "Each image must fit within the
boundaries of the Logical Screen, as defined in the
Logical Screen Descriptor." Also, do not accept
GIFs which have too much data for the image size.

R=nigeltao, jra, r
CC=bradfitz, golang-dev
https://golang.org/cl/7602045

On Darwin and FreeBSD, the mmap syscall return value is returned
unmodified. This means that the return value will either be a
valid address or a positive error number.

Also check return value from mmap in SysReserve - the callers of
SysReserve expect nil to be returned if the allocation failed.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7871043

Rather than just checking for ENOMEM, check for a return value of less
than 4096, so that we catch other errors such as EACCES and EINVAL.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7942043

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7958043

R=golang-dev, nigeltao
CC=golang-dev
https://golang.org/cl/7835046

data does not agree with its bounds.

R=r, jeff.allen
CC=golang-dev
https://golang.org/cl/7938043

Change from atoi to strtol since atoi does not set errno.

R=golang-dev, minux.ma, rsc, bradfitz
CC=golang-dev
https://golang.org/cl/7888047

R=adonovan, cw, patrick.allen.higgins, bradfitz
CC=golang-dev
https://golang.org/cl/7844045

Saves over 8KB of allocations per new connection.

benchmark                             old ns/op    new ns/op    delta
BenchmarkServerFakeConnNoKeepAlive        28777        24927  -13.38%

benchmark                            old allocs   new allocs    delta
BenchmarkServerFakeConnNoKeepAlive           52           46  -11.54%

benchmark                             old bytes    new bytes    delta
BenchmarkServerFakeConnNoKeepAlive        13716         5286  -61.46%

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7799047

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7927044

After the revert of revision 9ea9e7e6e0c8
the related revision 76ff7da868c6 must be reverted too.

Fixes #5102.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7961044

To be submitted once gc agrees.

R=rsc, iant, remyoudompheng
CC=golang-dev
https://golang.org/cl/7861045

Fixes #4813.

R=golang-dev, daniel.morsing, rsc
CC=golang-dev
https://golang.org/cl/7625050

-notes="BUG|TODO" instead of -notes="BUG,TODO".
Permits -notes=".*" to see all notes.

R=cnicolaou
CC=golang-dev
https://golang.org/cl/7951043

Also fix the examples to use stderr for errors.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7716052

If a handler didn't consume all its Request.Body, child.go was
closing the socket while the host was still writing to it,
causing the child to send a RST and the host (at least nginx)
to send an empty response body.

Now, we tell the host we're done with the request/response
first, and then close our input pipe after consuming a bit of
it. Consuming the body fixes the problem, and flushing to the
host first to tell it that we're done increases the chance
that the host cuts off further data to us, meaning we won't
have much to consume.

No new tests, because this package is lacking in tests.
Tested by hand with nginx.  See issue for testing details.

Fixes #4183

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7939045

Also adjust the implementation of applyRelocationsAMD64
so that the test added in CL 6848044 still passes.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/7686049

Fixes #1517.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7906043

Only the net stuff remains as significant work in the "minor changes" section.

R=golang-dev, dave, elias.naur, rsc
CC=golang-dev
https://golang.org/cl/7933044

XOR key into data 128 bits at a time instead of 64 bits
and pipeline half of state loads. Rotate loop to allow
single-register indexing for state[i].

On a MacBookPro10,2 (Core i5):

benchmark           old ns/op    new ns/op    delta
BenchmarkRC4_128          412          224  -45.63%
BenchmarkRC4_1K          3179         1613  -49.26%
BenchmarkRC4_8K         25223        12545  -50.26%

benchmark            old MB/s     new MB/s  speedup
BenchmarkRC4_128       310.51       570.42    1.84x
BenchmarkRC4_1K        322.09       634.48    1.97x
BenchmarkRC4_8K        320.97       645.32    2.01x

For comparison, on the same machine, openssl 0.9.8r reports
its rc4 speed as somewhat under 350 MB/s for both 1K and 8K
(it is operating 64 bits at a time).

On an Intel Xeon E5520:

benchmark           old ns/op    new ns/op    delta
BenchmarkRC4_128          418          259  -38.04%
BenchmarkRC4_1K          3200         1884  -41.12%
BenchmarkRC4_8K         25173        14529  -42.28%

benchmark            old MB/s     new MB/s  speedup
BenchmarkRC4_128       306.04       492.48    1.61x
BenchmarkRC4_1K        319.93       543.26    1.70x
BenchmarkRC4_8K        321.61       557.20    1.73x

For comparison, on the same machine, openssl 1.0.1
reports its rc4 speed as 587 MB/s for 1K and 601 MB/s for 8K.

R=agl
CC=golang-dev
https://golang.org/cl/7865046

fix code that implicitly assumes little-endian machines.

R=golang-dev, bradfitz, rsc, alex.brainman
CC=golang-dev
https://golang.org/cl/6792043

gcc generates only attr DW_AT_byte_size for DW_TAG_pointer_type of "void *",
but we used to also generate DW_AT_type pointing to imaginary unspecified
type "void", which confuses some gdb.
This change makes old Apple gdb 6.x (specifically, Apple version gdb-1515)
accepts our binary without issue like this:
(gdb) b 'main.main'
Die: DW_TAG_unspecified_type (abbrev = 10, offset = 47079)
    has children: FALSE
    attributes:
        DW_AT_name (DW_FORM_string) string: "void"
Dwarf Error: Cannot find type of die [in module /Users/minux/go/go2.hg/bin/go]

Special thanks to Russ Cox for pointing out the problem in comment #6 of
CL 7891044.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7744051

CL 7504044 accidentally reverted part of CL 7891044 and 7552045, this CL
bring those part back.

R=golang-dev
TBR=rsc
CC=golang-dev
https://golang.org/cl/7950045

R=rsc
CC=golang-dev
https://golang.org/cl/7949043

R=r
CC=golang-dev
https://golang.org/cl/7920048

-- amd64 --

On a MacBookPro10,2 (Core i5):

benchmark              old ns/op    new ns/op    delta
BenchmarkHash8Bytes          785          592  -24.59%
BenchmarkHash1K             8727         3014  -65.46%
BenchmarkHash8K            64926        20723  -68.08%

benchmark               old MB/s     new MB/s  speedup
BenchmarkHash8Bytes        10.19        13.50    1.32x
BenchmarkHash1K           117.34       339.71    2.90x
BenchmarkHash8K           126.17       395.31    3.13x

For comparison, on the same machine, openssl 0.9.8r reports
its sha1 speed as 341 MB/s for 1K and 404 MB/s for 8K.

On an Intel Xeon E5520:

benchmark              old ns/op    new ns/op    delta
BenchmarkHash8Bytes          984          707  -28.15%
BenchmarkHash1K            11141         3466  -68.89%
BenchmarkHash8K            82435        23411  -71.60%

benchmark               old MB/s     new MB/s  speedup
BenchmarkHash8Bytes         8.13        11.31    1.39x
BenchmarkHash1K            91.91       295.36    3.21x
BenchmarkHash8K            99.37       349.91    3.52x

For comparison, on the same machine, openssl 1.0.1 reports
its sha1 speed as 286 MB/s for 1K and 394 MB/s for 8K.

-- 386 --

On a MacBookPro10,2 (Core i5):

benchmark              old ns/op    new ns/op    delta
BenchmarkHash8Bytes         1041          713  -31.51%
BenchmarkHash1K            15612         3382  -78.34%
BenchmarkHash8K           110152        22733  -79.36%

benchmark               old MB/s     new MB/s  speedup
BenchmarkHash8Bytes         7.68        11.21    1.46x
BenchmarkHash1K            65.59       302.76    4.62x
BenchmarkHash8K            74.37       360.36    4.85x

On an Intel Xeon E5520:

benchmark              old ns/op    new ns/op    delta
BenchmarkHash8Bytes         1221          842  -31.04%
BenchmarkHash1K            14643         4137  -71.75%
BenchmarkHash8K           108722        27394  -74.80%

benchmark               old MB/s     new MB/s  speedup
BenchmarkHash8Bytes         6.55         9.49    1.45x
BenchmarkHash1K            69.93       247.51    3.54x
BenchmarkHash8K            75.35       299.04    3.97x

R=agl, dave
CC=golang-dev
https://golang.org/cl/7763049

-- amd64 --

On a MacBookPro10,2 (Core i5):

benchmark                       old ns/op    new ns/op    delta
BenchmarkHash8Bytes                   471          524  +11.25%
BenchmarkHash1K                      3018         2220  -26.44%
BenchmarkHash8K                     20634        14604  -29.22%
BenchmarkHash8BytesUnaligned          468          523  +11.75%
BenchmarkHash1KUnaligned             3006         2212  -26.41%
BenchmarkHash8KUnaligned            20820        14652  -29.63%

benchmark                        old MB/s     new MB/s  speedup
BenchmarkHash8Bytes                 16.98        15.26    0.90x
BenchmarkHash1K                    339.26       461.19    1.36x
BenchmarkHash8K                    397.00       560.92    1.41x
BenchmarkHash8BytesUnaligned        17.08        15.27    0.89x
BenchmarkHash1KUnaligned           340.65       462.75    1.36x
BenchmarkHash8KUnaligned           393.45       559.08    1.42x

For comparison, on the same machine, openssl 0.9.8r reports
its md5 speed as 350 MB/s for 1K and 410 MB/s for 8K.

On an Intel Xeon E5520:

benchmark                       old ns/op    new ns/op    delta
BenchmarkHash8Bytes                   565          607   +7.43%
BenchmarkHash1K                      3753         2475  -34.05%
BenchmarkHash8K                     25945        16250  -37.37%
BenchmarkHash8BytesUnaligned          559          594   +6.26%
BenchmarkHash1KUnaligned             3754         2474  -34.10%
BenchmarkHash8KUnaligned            26011        16359  -37.11%

benchmark                        old MB/s     new MB/s  speedup
BenchmarkHash8Bytes                 14.15        13.17    0.93x
BenchmarkHash1K                    272.83       413.58    1.52x
BenchmarkHash8K                    315.74       504.11    1.60x
BenchmarkHash8BytesUnaligned        14.31        13.46    0.94x
BenchmarkHash1KUnaligned           272.73       413.78    1.52x
BenchmarkHash8KUnaligned           314.93       500.73    1.59x

For comparison, on the same machine, openssl 1.0.1 reports
its md5 speed as 443 MB/s for 1K and 513 MB/s for 8K.

-- 386 --

On a MacBookPro10,2 (Core i5):

benchmark                       old ns/op    new ns/op    delta
BenchmarkHash8Bytes                   602          670  +11.30%
BenchmarkHash1K                      4038         2549  -36.87%
BenchmarkHash8K                     27879        16690  -40.13%
BenchmarkHash8BytesUnaligned          602          670  +11.30%
BenchmarkHash1KUnaligned             4025         2546  -36.75%
BenchmarkHash8KUnaligned            27844        16692  -40.05%

benchmark                        old MB/s     new MB/s  speedup
BenchmarkHash8Bytes                 13.28        11.93    0.90x
BenchmarkHash1K                    253.58       401.69    1.58x
BenchmarkHash8K                    293.83       490.81    1.67x
BenchmarkHash8BytesUnaligned        13.27        11.94    0.90x
BenchmarkHash1KUnaligned           254.40       402.05    1.58x
BenchmarkHash8KUnaligned           294.21       490.77    1.67x

On an Intel Xeon E5520:

benchmark                       old ns/op    new ns/op    delta
BenchmarkHash8Bytes                   752          716   -4.79%
BenchmarkHash1K                      5307         2799  -47.26%
BenchmarkHash8K                     36993        18042  -51.23%
BenchmarkHash8BytesUnaligned          748          730   -2.41%
BenchmarkHash1KUnaligned             5301         2795  -47.27%
BenchmarkHash8KUnaligned            36983        18085  -51.10%

benchmark                        old MB/s     new MB/s  speedup
BenchmarkHash8Bytes                 10.64        11.16    1.05x
BenchmarkHash1K                    192.93       365.80    1.90x
BenchmarkHash8K                    221.44       454.03    2.05x
BenchmarkHash8BytesUnaligned        10.69        10.95    1.02x
BenchmarkHash1KUnaligned           193.15       366.36    1.90x
BenchmarkHash8KUnaligned           221.51       452.96    2.04x

R=agl
CC=golang-dev
https://golang.org/cl/7621049

-- amd64 --

On a MacBookPro10,2 (Core i5):

benchmark           old ns/op    new ns/op    delta
BenchmarkRC4_128          470          421  -10.43%
BenchmarkRC4_1K          3123         3275   +4.87%
BenchmarkRC4_8K         26351        25866   -1.84%

benchmark            old MB/s     new MB/s  speedup
BenchmarkRC4_128       272.22       303.40    1.11x
BenchmarkRC4_1K        327.80       312.58    0.95x
BenchmarkRC4_8K        307.24       313.00    1.02x

For comparison, on the same machine, openssl 0.9.8r reports
its rc4 speed as somewhat under 350 MB/s for both 1K and 8K.
The Core i5 performance can be boosted another 20%, but only
by making the Xeon performance significantly slower.

On an Intel Xeon E5520:

benchmark           old ns/op    new ns/op    delta
BenchmarkRC4_128          774          417  -46.12%
BenchmarkRC4_1K          6121         3200  -47.72%
BenchmarkRC4_8K         48394        25151  -48.03%

benchmark            old MB/s     new MB/s  speedup
BenchmarkRC4_128       165.18       306.84    1.86x
BenchmarkRC4_1K        167.28       319.92    1.91x
BenchmarkRC4_8K        167.29       321.89    1.92x

For comparison, on the same machine, openssl 1.0.1
(which uses a different implementation than 0.9.8r)
reports its rc4 speed as 587 MB/s for 1K and 601 MB/s for 8K.
It is using SIMD instructions to do more in parallel.

So there's still some improvement to be had, but even so,
this is almost 2x faster than what it replaced.

-- 386 --

On a MacBookPro10,2 (Core i5):

benchmark           old ns/op    new ns/op    delta
BenchmarkRC4_128         3491          421  -87.94%
BenchmarkRC4_1K         28063         3205  -88.58%
BenchmarkRC4_8K        220392        25228  -88.55%

benchmark            old MB/s     new MB/s  speedup
BenchmarkRC4_128        36.66       303.81    8.29x
BenchmarkRC4_1K         36.49       319.42    8.75x
BenchmarkRC4_8K         36.73       320.90    8.74x

On an Intel Xeon E5520:

benchmark           old ns/op    new ns/op    delta
BenchmarkRC4_128         2268          524  -76.90%
BenchmarkRC4_1K         18161         4137  -77.22%
BenchmarkRC4_8K        142396        32350  -77.28%

benchmark            old MB/s     new MB/s  speedup
BenchmarkRC4_128        56.42       244.13    4.33x
BenchmarkRC4_1K         56.38       247.46    4.39x
BenchmarkRC4_8K         56.86       250.26    4.40x

R=agl
CC=golang-dev
https://golang.org/cl/7547050

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