We could undoubtedly squeeze even more out of these loops, and in the
long term, a better compiler would be smarter with bounds checks, but in
the short term, this small change is an easy win.

benchmark                      old ns/op     new ns/op     delta
BenchmarkFillOver-8            1619470       1323192       -18.29%
BenchmarkCopyOver-8            1129369       1062787       -5.90%
BenchmarkGlyphOver-8           420070        378608        -9.87%

On github.com/golang/freetype/truetype's BenchmarkDrawString:
benchmark                 old ns/op     new ns/op     delta
BenchmarkDrawString-8     9561435       8807019       -7.89%

Change-Id: Ib1c6271ac18bced85e0fb5ebf250dd57d7747e75
Reviewed-on: https://go-review.googlesource.com/14093Reviewed-by: Rob Pike <r@golang.org>

This may fix the flakiness on Windows/x64, assuming that it's actually
due to a variance in the connection time which slightly exceeds 100ms.

150ms + 95ms = 245ms, which is still low enough to avoid triggering
Happy Eyeballs (300ms) on non-Windows platforms.

Updates #12309

Change-Id: I816a36fbc0a3e5c90e3cf1b75a134faf0d91557c
Reviewed-on: https://go-review.googlesource.com/14120
Run-TryBot: Paul Marks <pmarks@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Update #10994

CASE and BCASE were used by 5c in switch statements, cmd/compile
does not use them.

Change-Id: I7a578c461b52b94690e35460926849b28971b770
Reviewed-on: https://go-review.googlesource.com/14009Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The hash tests generate occasional failures, quiet them some more.

In particular we can get 1 collision when the expected number is
.001 or so. That shouldn't be a dealbreaker.

Fixes #12311

Change-Id: I784e91b5d21f4f1f166dc51bde2d1cd3a7a3bfea
Reviewed-on: https://go-review.googlesource.com/13902Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Fixes #12340.

Change-Id: I17a8b3711a8593ec60882a0dcadb38f0cc138f4b
Reviewed-on: https://go-review.googlesource.com/13949Reviewed-by: Rob Pike <r@golang.org>

Change-Id: I15bf55aa5ac3588c05f0a253f583c52bab209892
Reviewed-on: https://go-review.googlesource.com/14041Reviewed-by: Dave Cheney <dave@cheney.net>

Change-Id: If0d00999c58f7421e4da06e1822ba5abccf72cac
Reviewed-on: https://go-review.googlesource.com/14111Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This is basic validation and should be performed early

Fixes #12412

Change-Id: I903f7eeafdc22376704985a53d649698cf9d8ef4
Reviewed-on: https://go-review.googlesource.com/14110Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #10994

CASE and BCASE were used by 7c in switch statements, cmd/compile
does not use them, cmd/assemble couldn't assemble them, and the arm64
peephole optimiser didn't know about them.

Change-Id: Id04835fcb37e207f76d211ce54a4db9c057d6112
Reviewed-on: https://go-review.googlesource.com/14100Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Run-TryBot: Aram Hăvărneanu <aram@mgk.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>

All implementations of File.read ensure that n >= 0. This is usually via
fixCount, except for Windows console reads, which only ever add to n.

Change-Id: Ic019d6a2da5ef1ac68d2690c908deca4fcc6b4a4
Reviewed-on: https://go-review.googlesource.com/12624Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This helps vet see a real issue:

    cmd/internal/gc$ go vet
    gen.go:1223: unreachable code

Fixes #12106.

Change-Id: I720868b07ae6b6d5a4dc6b238baa8c9c889da6d8
Reviewed-on: https://go-review.googlesource.com/14083Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

And clean up the mess on arm64 (the mess on arm is too confusing).

See issue #10050

Change-Id: I2ce813fe8646d4e818eb660612a7e4b2bb04de4c
Reviewed-on: https://go-review.googlesource.com/13884Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes external linking of net/http tests (or anything that uses
sendfile).

Fixes #12390.

Change-Id: Iee08998cf66e7b0ce851db138a00ebae6dc2395e
Reviewed-on: https://go-review.googlesource.com/14072Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>

Currently the stack barrier stub blindly unwinds the next stack
barrier from the G's stack barrier array without checking that it's
the right stack barrier. If through some bug the stack barrier array
position gets out of sync with where we actually are on the stack,
this could return to the wrong PC, which would lead to difficult to
debug crashes. To address this, this commit adds a check to the amd64
stack barrier stub that it's unwinding the correct stack barrier.

Updates #12238.

Change-Id: If824d95191d07e2512dc5dba0d9978cfd9f54e02
Reviewed-on: https://go-review.googlesource.com/13948Reviewed-by: Russ Cox <rsc@golang.org>

Currently enabling the debugging mode where stack barriers are
installed at every frame requires recompiling the runtime. However,
this is potentially useful for field debugging and for runtime tests,
so make this mode a GODEBUG.

Updates #12238.

Change-Id: I6fb128f598b19568ae723a612e099c0ed96917f5
Reviewed-on: https://go-review.googlesource.com/13947Reviewed-by: Russ Cox <rsc@golang.org>

Currently the runtime can install stack barriers in any frame.
However, the frame of cgocallback_gofunc is special: it's the one
function that switches from a regular G stack to the system stack on
return. Hence, the return PC slot in its frame on the G stack is
actually used to save getg().sched.pc (so tracebacks appear to unwind
to the last Go function running on that G), and not as an actual
return PC for cgocallback_gofunc.

Because of this, if we install a stack barrier in cgocallback_gofunc's
return PC slot, when cgocallback_gofunc does return, it will move the
stack barrier stub PC in to getg().sched.pc and switch back to the
system stack. The rest of the runtime doesn't know how to deal with a
stack barrier stub in sched.pc: nothing knows how to match it up with
the G's stack barrier array and, when the runtime removes stack
barriers, it doesn't know to undo the one in sched.pc. Hence, if the C
code later returns back in to Go code, it will attempt to return
through the stack barrier saved in sched.pc, which may no longer have
correct unwinding information.

Fix this by blacklisting cgocallback_gofunc's frame so the runtime
won't install a stack barrier in it's return PC slot.

Fixes #12238.

Change-Id: I46aa2155df2fd050dd50de3434b62987dc4947b8
Reviewed-on: https://go-review.googlesource.com/13944Reviewed-by: Russ Cox <rsc@golang.org>

(See referenced bug for details.)

Fixes #11966.

Change-Id: I91f9c95594cf4fd6d25d9a81f155a643c7a1f8e0
Reviewed-on: https://go-review.googlesource.com/13038Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

https://tools.ietf.org/html/rfc7301#section-3.1 specifies that a
ProtocolName may not be empty. This change enforces this for ServerHello
messages—it's already enforced for ClientHello messages.

Change-Id: Ic5a5be6bebf07fba90a3cabd10b07ab7b4337f53
Reviewed-on: https://go-review.googlesource.com/12003Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

In Go 1.5, Config.Certificates is no longer required if
Config.GetCertificate has been set. This change updated four comments to
reflect that.

Change-Id: Id72cc22fc79e931b2d645a7c3960c3241042762c
Reviewed-on: https://go-review.googlesource.com/13800Reviewed-by: Adam Langley <agl@golang.org>

The existing implementation didn't use the CLMUL instructions for fast
and constant time binary-field multiplication. With this change, amd64
CPUs that support both AES and CLMUL instructions will use an optimised
asm implementation.

benchmark                 old ns/op     new ns/op     delta
BenchmarkAESGCMSeal8K     91723         3200          -96.51%
BenchmarkAESGCMOpen8K     91487         3324          -96.37%
BenchmarkAESGCMSeal1K     11873         546           -95.40%
BenchmarkAESGCMOpen1K     11833         594           -94.98%

benchmark                 old MB/s     new MB/s     speedup
BenchmarkAESGCMSeal8K     89.31        2559.62      28.66x
BenchmarkAESGCMOpen8K     89.54        2463.78      27.52x
BenchmarkAESGCMSeal1K     86.24        1872.49      21.71x
BenchmarkAESGCMOpen1K     86.53        1721.78      19.90x

Change-Id: Idd63233098356d8b353d16624747b74d0c3f193e
Reviewed-on: https://go-review.googlesource.com/10484
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>

Go 1.5 allowed TLS connections where Config.Certificates was nil as long
as the GetCertificate callback was given. However, tls.Listen wasn't
updated accordingly until this change.

Change-Id: I5f67f323f63c988ff79642f3daf8a6b2a153e6b2
Reviewed-on: https://go-review.googlesource.com/13801Reviewed-by: Adam Langley <agl@golang.org>

Recursive types R containing slices of R's did not terminate despite the
effort in CL 10821.

For recursive types there was a competition between slice expansion by a
factor 'complexSize', and termination with probability '1/complexSize'
which lead to stack overflow as soon as a recursive struct had slices
pointing to its own type.

Fix this by shrinking the size hint as a function of recursion depth.
This has the dual effect of reducing the number of elements generated
per slice and also increasing the probability for termination.

Fixes #11148.

Change-Id: Ib61155b4f2e2de3873d508d63a1f4be759426d67
Reviewed-on: https://go-review.googlesource.com/13830Reviewed-by: Adam Langley <agl@golang.org>

For primes which are 3 mod 4, using Tonelli-Shanks is slower
and more complicated than using the identity

     a**((p+1)/4) mod p == sqrt(a)

For 2^450-2^225-1 and 2^10860-2^5430-1, which are 3 mod 4:

BenchmarkModSqrt225_TonelliTri      1000     1135375 ns/op
BenchmarkModSqrt225_3Mod4          10000      156009 ns/op
BenchmarkModSqrt5430_Tonelli           1  3448851386 ns/op
BenchmarkModSqrt5430_3Mod4             2   914616710 ns/op

~2.6x to 7x faster.

Fixes #11437 (which is a prime choice of issues to fix)

Change-Id: I813fb29454160483ec29825469e0370d517850c2
Reviewed-on: https://go-review.googlesource.com/11522Reviewed-by: Adam Langley <agl@golang.org>

Fixes #11127.

Change-Id: Ibcfc3a05e91fa4260d70b04bee2bbba2376bd313
Reviewed-on: https://go-review.googlesource.com/13923Reviewed-by: Adam Langley <agl@golang.org>

Should only matter on ppc64 and ppc64le.

Fixes #11336

Change-Id: Id4b0ac28b573648e1aa98e87bf010f00d006b146
Reviewed-on: https://go-review.googlesource.com/13901Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

Change-Id: I33c2c222ea884d9ff57800ea5185644b5d8e591a
Reviewed-on: https://go-review.googlesource.com/14034Reviewed-by: Minux Ma <minux@golang.org>

Update testzip.proto to reflect vendoring of golang.org/x/arch.

Change-Id: I532da1100f74d1e9887eb3cf26974660ae818d92
Reviewed-on: https://go-review.googlesource.com/14007Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Ib79ab787fdc90a5a29b25474d91afa9bfaf51276
Reviewed-on: https://go-review.googlesource.com/13589Reviewed-by: Minux Ma <minux@golang.org>

Val.Ctype used to be struct field, it's now a method.

Change-Id: I08f0b32b66dba15b2a392e84a557efb905b530cb
Reviewed-on: https://go-review.googlesource.com/14031Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #12361.

Change-Id: Ifd62e8d93b2d733e67e0186c7185cd6291d3bbc1
Reviewed-on: https://go-review.googlesource.com/13939Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The code is now in cmd/vendor/golang.org/x/arch.

Change-Id: I518d48c21b0d7fed914552b89ee41411f088456b
Reviewed-on: https://go-review.googlesource.com/14021Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I5348774ff01a5f0f706a1dba4aa9500661841f47
Reviewed-on: https://go-review.googlesource.com/14020Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

For use by cmd/objdump in place of the current cmd/internal/rsc.io/... tree.

Change-Id: I7d765ddf43ab4118a3221fd755ff0a2a02daa5de
Reviewed-on: https://go-review.googlesource.com/13979Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Right now we find out implicitly if stack barriers are in place,
or defers. This change makes sure we find out about short
unwinds always.

Change-Id: Ibdde1ba9c79eb792660dcb7aa6f186e4e4d559b3
Reviewed-on: https://go-review.googlesource.com/13966Reviewed-by: Austin Clements <austin@google.com>

Change-Id: I34eff138c61e5ad456a4918c402ca0e8333601a0
Reviewed-on: https://go-review.googlesource.com/13978Reviewed-by: Russ Cox <rsc@golang.org>

Start go1.6.txt with a note that nacl ports are no longer
restricted to pepper_41 and a record of the text/template change.

Change-Id: I21dda64aec113c35caf1d565f29e3aac8171480a
Reviewed-on: https://go-review.googlesource.com/14004Reviewed-by: Rob Pike <r@golang.org>

GetMUIStringValue tries as a convenience to resolve string values even for pathless
resource DLLs by searching the system directory (one of several paths used
by the system's standard DLL search order algorithm). This would not be
needed if regLoadMUIString searched for pathless DLLs itself, but it
doesn't, instead it needs an absolute path, otherwise it will fail.

This approach works fine for solving issue #12015 (handle localized time
zone names; for which GetMUIStringValue was created) since tzres.dll that
is used to resolve localized time zone names has no path in the registry
but is located under the system directory.

However, this approach will fail if a pathless DLL is located somewhere
else than the system directory.

Because of this limitation GetMUIStringValue may have to be revised in the
future to allow for custom paths, possibly through another version of the
function.

See also:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms724890%28v=vs.85%29.aspx
https://msdn.microsoft.com/en-us/library/windows/desktop/ms682586%28v=vs.85%29.aspx

Change-Id: Ida66a0ef1928e0461ce248c795827902d785e6cd
Reviewed-on: https://go-review.googlesource.com/13929Reviewed-by: Rob Pike <r@golang.org>

Fixes #11961

Minux removed the use of SRPC in 003dccfa, but the SRPC name service
code was left in the tree. SRPC was removed in pepper_42 making the
code, which ran on startup, fail, even though it was not used.

Removing srpc_nacl.go for a total diff of -822 lines has got to count
as one of the easiest nacl fixes we've had to date.

Change-Id: Ic4e348146bfe47450bbb9cabb91699ba153e6bf0
Reviewed-on: https://go-review.googlesource.com/13958Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Issue 6754 reports that Go bzip2 Decode function is much slower
(about 2.5x in go1.5) than the Python equivalent (which is
actually just a wrapper around the usual C library) on random data.

Profiling the code shows that half a dozen of CMP instructions in a
tight loop are responsibile for most of the execution time.

This patch reduces the number of branches of the loop, greatly
improving performance on random data and speeding up decoding of
real data.

name            old time/op    new time/op    delta
DecodeDigits-4    9.28ms ± 1%    8.05ms ± 1%  -13.18%  (p=0.000 n=15+14)
DecodeTwain-4     28.9ms ± 2%    26.4ms ± 1%   -8.57%  (p=0.000 n=15+14)
DecodeRand-4      3.94ms ± 1%    3.06ms ± 1%  -22.45%  (p=0.000 n=15+14)

name            old speed      new speed      delta
DecodeDigits-4  4.65MB/s ± 1%  5.36MB/s ± 1%  +15.21%  (p=0.000 n=13+14)
DecodeTwain-4   4.32MB/s ± 2%  4.72MB/s ± 1%   +9.36%  (p=0.000 n=15+14)
DecodeRand-4    4.27MB/s ± 1%  5.51MB/s ± 1%  +28.86%  (p=0.000 n=15+14)

I've run some benchmark comparing Go bzip2 implementation with the
usual Linux bzip2 command (which is written in C). On my machine
this patch brings go1.5
  from ~2.26x to ~1.50x of bzip2 time (on 64MB  random data)
  from ~1.70x to ~1.50x of bzip2 time (on 100MB english text)
  from ~2.00x to ~1.88x of bzip2 time (on 64MB  /dev/zero data)

Fixes #6754

Change-Id: I3cb12d2c0c2243c1617edef1edc88f05f91d26d1
Reviewed-on: https://go-review.googlesource.com/13853Reviewed-by: Nigel Tao <nigeltao@golang.org>

This changed in https://golang.org/cl/10761.

Update #12203.

Change-Id: Ia37ebb7ecba689ad3cb2559213d675f21cf03a95
Reviewed-on: https://go-review.googlesource.com/13799Reviewed-by: Russ Cox <rsc@golang.org>