cmd/go: fix typo in comment

Thanks to deafgoat.

Fixes #15215

Change-Id: I9fababc7ecd201ce86020a438e4faee95e7623a8
Reviewed-on: https://go-review.googlesource.com/21792
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

runtime: revert "do not call timeBeginPeriod on windows"

This reverts commit ab4c9298b8185a056ff1152f2c7bd9b38d3d06f3.

Sysmon critically depends on system timer resolution for retaking
of Ps blocked in system calls. See #14790 for an example
of a program where execution time goes from 2ms to 30ms if
timeBeginPeriod(1) is not used.

We can remove timeBeginPeriod(1) when we support UMS (#7876).

Update #14790

Change-Id: I362b56154359b2c52d47f9f2468fe012b481cf6d
Reviewed-on: https://go-review.googlesource.com/20834
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

cmd/internal/bio: move Bgetc to link/internal/ld

Also, remove bio.Brdline.

Change-Id: I3e0caed27a373fd71737cf6892de5e8fc208b776
Reviewed-on: https://go-review.googlesource.com/21783
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>

cmd: remove unused code

Generated with honnef.co/go/unused

There is a large amount of unused code in cmd/internal/obj/s390x but
that can wait til the s390x port is merged.

There is some unused code in
cmd/internal/unvendor/golang.org/x/arch/arm/armasm but that should be
addressed upstream and a new revision imported.

Change-Id: I252c0f9ea8c5bb1a0b530a374ef13a0a20ea56aa
Reviewed-on: https://go-review.googlesource.com/21782
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>

cmd/internal/bio: embed bufio.{Reader,Writer} in bio.{Reader,Writer}

Change-Id: Ie95b0b0d4f724f4769cf2d4f8063cb5019fa9bc9
Reviewed-on: https://go-review.googlesource.com/21781
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd: remove bio.BufReader and bio.BufWriter

bio.BufReader was never used.

bio.BufWriter was used to wrap an existing io.Writer, but the
bio.Writer returned would not be seekable, so replace all occurences
with bufio.Reader instead.

Change-Id: I9c6779e35c63178aa4e104c17bb5bb8b52de0359
Reviewed-on: https://go-review.googlesource.com/21722
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/link/internal: make ld.Bso a *bio.Writer

This is a pre requesite of CL 21722 and removes a lot of unidiomatic
boilerplate in the linker.

Change-Id: If7491b88212b2be7b0c8c588e9c196839131f8ad
Reviewed-on: https://go-review.googlesource.com/21780
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/cgo: fix cgo with gccgo

Change-Id: I1780899255e22c16d7f8e9947609a1c284d7c42e
Reviewed-on: https://go-review.googlesource.com/21690
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/compile: insert instrumentation more carefully in racewalk

Be more careful about inserting instrumentation in racewalk.
If the node being instrumented is an OAS, and it has a non-
empty Ninit, then append instrumentation to the Ninit list
rather than letting it be inserted before the OAS (and the
compilation of its init list).  This deals with the case that
the Ninit list defines a variable used in the RHS of the OAS.

Fixes #15091.

Change-Id: Iac91696d9104d07f0bf1bd3499bbf56b2e1ef073
Reviewed-on: https://go-review.googlesource.com/21771
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: David Chase <drchase@google.com>

runtime: emit file:line info into traces

This makes traces self-contained and simplifies trace workflow
in modern cloud environments where it is simpler to reach
a service via HTTP than to obtain the binary.

Change-Id: I6ff3ca694dc698270f1e29da37d5efaf4e843a0d
Reviewed-on: https://go-review.googlesource.com/21732
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

cmd/cgo: increase s390x int type size to 8 bytes

The size of the int type in Go on s390x is 8 bytes, not 4.

Change-Id: I1a71ce8c9925f3499abb61c1aa4f6fa2d2ec0d7e
Reviewed-on: https://go-review.googlesource.com/21760
Reviewed-by: Bill O'Farrell <billotosyr@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

bytes: add ContainsRune

Make package bytes consistent with strings
by adding missing function ContainsRune.

Fixes #15189

Change-Id: Ie09080b389e55bbe070c57aa3bd134053a805423
Reviewed-on: https://go-review.googlesource.com/21710
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

syscall: add assembly for Linux on s390x

Change-Id: I42ade65a91f3effc03dd663ee449410baa9f8ca8
Reviewed-on: https://go-review.googlesource.com/21740
Reviewed-by: Bill O'Farrell <billotosyr@gmail.com>
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

context: disable more flaky tests on openbsd

Updates #15158

Change-Id: Icb3788152a7a5a9b0d56ea38da46d770ffdce413
Reviewed-on: https://go-review.googlesource.com/21763
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

test: skip nilptr3 test on s390x

Fails for the same reason as ppc64 and mips64 (incomplete
optimization).

Change-Id: Ieb4d997fc27d4f2b756e63dd7f588abe10c0213a
Reviewed-on: https://go-review.googlesource.com/20963
Reviewed-by: Bill O'Farrell <billotosyr@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/link: add s390x to link tool main function

Change-Id: I83bc2b4a00216b069f133113e4ae9ad76c98a708
Reviewed-on: https://go-review.googlesource.com/21741
Run-TryBot: Michael Munday <munday@ca.ibm.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

io: change the name of ReadAtSizer to SizedReaderAt

This is a proposal. The old name is pretty poor. The new one describes
it better and may be easier to remember. It does not start with Read,
though I think that inconsistency is worthwhile.

Reworded the comment a bit for clarity.

Change-Id: Icb4f9c663cc68958e0363d7ff78a0b29cc521f98
Reviewed-on: https://go-review.googlesource.com/21629
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd: replace bio.Buf with bio.Reader and bio.Writer

Replace the bidirectional bio.Buf type with a pair of unidirectional
buffered seekable Reader and Writers.

Change-Id: I86664a06f93c94595dc67c2cbd21356feb6680ef
Reviewed-on: https://go-review.googlesource.com/21720
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/compile: cleanup -dynlink/-shared support check

Moves the list of architectures that support shared libraries into
a function. Also adds s390x to that list.

Change-Id: I99c8a9f6cd4816ce3d53abaabaf8d002e25e6b28
Reviewed-on: https://go-review.googlesource.com/21661
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Run-TryBot: Michael Munday <munday@ca.ibm.com>

cmd/compile/internal/gc: unexport Export

Export does not need to be exported.

Change-Id: I252f0c024732f1d056817cab13e8e3c589b54d13
Reviewed-on: https://go-review.googlesource.com/21721
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/go: fix failing tests since vet was moved from x/tools

Change-Id: I3276a118ced78f3efd8f1bc5fb8b8fa2fde52496
Reviewed-on: https://go-review.googlesource.com/21704
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

net/http: fixed trivial go vet warnings

Updates #15177

Change-Id: I748f025461f313b5b426821ead695f90d3011a6b
Reviewed-on: https://go-review.googlesource.com/21677
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/compile: Fix constant-folding of unsigned shifts

Make sure the results of unsigned constant-folded
shifts are sign-extended into the AuxInt field.

Fixes #15175

Change-Id: I3490d1bc3d9b2e1578ed30964645508577894f58
Reviewed-on: https://go-review.googlesource.com/21586
Reviewed-by: Alexandru Moșoi <alexandru@mosoi.ro>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/go: revise importPath when ImportPath is 'command-line-arguments'

Fixes #14613

Change-Id: I40d9696db3879549e78373ef17f6c92bd4b3470b
Reviewed-on: https://go-review.googlesource.com/21596
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

bytes, string: add Reset method to Reader

Currently, there is no easy allocation-free way to turn a
[]byte or string into an io.Reader. Thus, we add a Reset method
to bytes.Reader and strings.Reader to allow the reuse of these
Readers with another []byte or string.

This is consistent with the fact that many standard library io.Readers
already support a Reset method of some type:
bufio.Reader
flate.Reader
gzip.Reader
zlib.Reader
debug/dwarf.LineReader
bytes.Buffer
crypto/rc4.Cipher

Fixes #15033

Change-Id: I456fd1af77af6ef0b4ac6228b058ac1458ff3d19
Reviewed-on: https://go-review.googlesource.com/21386
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

runtime: add s390x support (new files and lfstack_64bit.go modifications)

Change-Id: I51c0a332e3cbdab348564e5dcd27583e75e4b881
Reviewed-on: https://go-review.googlesource.com/20946
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/link: hide go.dwarf symbols

Fixes #15179

Change-Id: I0f70b7ae1682eafaece7f22d8e76f0aa806f3ec9
Reviewed-on: https://go-review.googlesource.com/21589
Run-TryBot: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/link: disable DWARF when not generating symtab

Fixes #15166

Change-Id: I30284e3c0fb2c80b26a2572e2fb249b8018e85f9
Reviewed-on: https://go-review.googlesource.com/21587
Run-TryBot: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

C: fix jbd's identity

Change-Id: Ib4353710a742b1067723c7c6186e8639559668a3
Reviewed-on: https://go-review.googlesource.com/21655
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

context: mark more tests as flaky on OpenBSD

Updates #15158

Change-Id: I53e9e68d36efbf52736822e6caa047cfff501283
Reviewed-on: https://go-review.googlesource.com/21653
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

math/big: re-use memory in Int.GCD

This improves TLS handshake performance.

benchmark                                 old ns/op     new ns/op     delta
BenchmarkGCD10x10/WithoutXY-4             965           968           +0.31%
BenchmarkGCD10x10/WithXY-4                1813          1391          -23.28%
BenchmarkGCD10x100/WithoutXY-4            1093          1075          -1.65%
BenchmarkGCD10x100/WithXY-4               2348          1676          -28.62%
BenchmarkGCD10x1000/WithoutXY-4           1569          1565          -0.25%
BenchmarkGCD10x1000/WithXY-4              4262          3242          -23.93%
BenchmarkGCD10x10000/WithoutXY-4          6069          6066          -0.05%
BenchmarkGCD10x10000/WithXY-4             12123         11331         -6.53%
BenchmarkGCD10x100000/WithoutXY-4         52664         52610         -0.10%
BenchmarkGCD10x100000/WithXY-4            97494         95649         -1.89%
BenchmarkGCD100x100/WithoutXY-4           5244          5228          -0.31%
BenchmarkGCD100x100/WithXY-4              22572         18630         -17.46%
BenchmarkGCD100x1000/WithoutXY-4          6143          6233          +1.47%
BenchmarkGCD100x1000/WithXY-4             24652         19357         -21.48%
BenchmarkGCD100x10000/WithoutXY-4         15725         15804         +0.50%
BenchmarkGCD100x10000/WithXY-4            60552         55973         -7.56%
BenchmarkGCD100x100000/WithoutXY-4        107008        107853        +0.79%
BenchmarkGCD100x100000/WithXY-4           349597        340994        -2.46%
BenchmarkGCD1000x1000/WithoutXY-4         63785         64434         +1.02%
BenchmarkGCD1000x1000/WithXY-4            373186        334035        -10.49%
BenchmarkGCD1000x10000/WithoutXY-4        78038         78241         +0.26%
BenchmarkGCD1000x10000/WithXY-4           543692        507034        -6.74%
BenchmarkGCD1000x100000/WithoutXY-4       205607        207727        +1.03%
BenchmarkGCD1000x100000/WithXY-4          2488113       2415323       -2.93%
BenchmarkGCD10000x10000/WithoutXY-4       1731340       1714992       -0.94%
BenchmarkGCD10000x10000/WithXY-4          10601046      7111329       -32.92%
BenchmarkGCD10000x100000/WithoutXY-4      2239155       2212173       -1.21%
BenchmarkGCD10000x100000/WithXY-4         30097040      26538887      -11.82%
BenchmarkGCD100000x100000/WithoutXY-4     119845326     119863916     +0.02%
BenchmarkGCD100000x100000/WithXY-4        768006543     426795966     -44.43%

benchmark                                 old allocs     new allocs     delta
BenchmarkGCD10x10/WithoutXY-4             5              5              +0.00%
BenchmarkGCD10x10/WithXY-4                17             9              -47.06%
BenchmarkGCD10x100/WithoutXY-4            6              6              +0.00%
BenchmarkGCD10x100/WithXY-4               21             9              -57.14%
BenchmarkGCD10x1000/WithoutXY-4           6              6              +0.00%
BenchmarkGCD10x1000/WithXY-4              30             12             -60.00%
BenchmarkGCD10x10000/WithoutXY-4          6              6              +0.00%
BenchmarkGCD10x10000/WithXY-4             26             12             -53.85%
BenchmarkGCD10x100000/WithoutXY-4         6              6              +0.00%
BenchmarkGCD10x100000/WithXY-4            28             12             -57.14%
BenchmarkGCD100x100/WithoutXY-4           5              5              +0.00%
BenchmarkGCD100x100/WithXY-4              183            61             -66.67%
BenchmarkGCD100x1000/WithoutXY-4          8              8              +0.00%
BenchmarkGCD100x1000/WithXY-4             170            47             -72.35%
BenchmarkGCD100x10000/WithoutXY-4         8              8              +0.00%
BenchmarkGCD100x10000/WithXY-4            200            67             -66.50%
BenchmarkGCD100x100000/WithoutXY-4        8              8              +0.00%
BenchmarkGCD100x100000/WithXY-4           188            65             -65.43%
BenchmarkGCD1000x1000/WithoutXY-4         5              5              +0.00%
BenchmarkGCD1000x1000/WithXY-4            2435           1193           -51.01%
BenchmarkGCD1000x10000/WithoutXY-4        8              8              +0.00%
BenchmarkGCD1000x10000/WithXY-4           2211           1076           -51.33%
BenchmarkGCD1000x100000/WithoutXY-4       8              8              +0.00%
BenchmarkGCD1000x100000/WithXY-4          2271           1108           -51.21%
BenchmarkGCD10000x10000/WithoutXY-4       5              5              +0.00%
BenchmarkGCD10000x10000/WithXY-4          23183          11605          -49.94%
BenchmarkGCD10000x100000/WithoutXY-4      8              8              +0.00%
BenchmarkGCD10000x100000/WithXY-4         23421          11717          -49.97%
BenchmarkGCD100000x100000/WithoutXY-4     5              5              +0.00%
BenchmarkGCD100000x100000/WithXY-4        232976         116815         -49.86%

benchmark                                 old bytes      new bytes     delta
BenchmarkGCD10x10/WithoutXY-4             208            208           +0.00%
BenchmarkGCD10x10/WithXY-4                736            432           -41.30%
BenchmarkGCD10x100/WithoutXY-4            256            256           +0.00%
BenchmarkGCD10x100/WithXY-4               896            432           -51.79%
BenchmarkGCD10x1000/WithoutXY-4           368            368           +0.00%
BenchmarkGCD10x1000/WithXY-4              1856           1152          -37.93%
BenchmarkGCD10x10000/WithoutXY-4          1616           1616          +0.00%
BenchmarkGCD10x10000/WithXY-4             7920           7376          -6.87%
BenchmarkGCD10x100000/WithoutXY-4         13776          13776         +0.00%
BenchmarkGCD10x100000/WithXY-4            68800          68176         -0.91%
BenchmarkGCD100x100/WithoutXY-4           208            208           +0.00%
BenchmarkGCD100x100/WithXY-4              6960           2112          -69.66%
BenchmarkGCD100x1000/WithoutXY-4          544            560           +2.94%
BenchmarkGCD100x1000/WithXY-4             7280           2400          -67.03%
BenchmarkGCD100x10000/WithoutXY-4         2896           2912          +0.55%
BenchmarkGCD100x10000/WithXY-4            15280          10002         -34.54%
BenchmarkGCD100x100000/WithoutXY-4        27344          27365         +0.08%
BenchmarkGCD100x100000/WithXY-4           88288          83427         -5.51%
BenchmarkGCD1000x1000/WithoutXY-4         544            544           +0.00%
BenchmarkGCD1000x1000/WithXY-4            178288         40043         -77.54%
BenchmarkGCD1000x10000/WithoutXY-4        3344           3136          -6.22%
BenchmarkGCD1000x10000/WithXY-4           188720         54432         -71.16%
BenchmarkGCD1000x100000/WithoutXY-4       27792          27592         -0.72%
BenchmarkGCD1000x100000/WithXY-4          373872         239447        -35.95%
BenchmarkGCD10000x10000/WithoutXY-4       4288           4288          +0.00%
BenchmarkGCD10000x10000/WithXY-4          11935584       481875        -95.96%
BenchmarkGCD10000x100000/WithoutXY-4      31296          28834         -7.87%
BenchmarkGCD10000x100000/WithXY-4         13237088       1662620       -87.44%
BenchmarkGCD100000x100000/WithoutXY-4     40768          40768         +0.00%
BenchmarkGCD100000x100000/WithXY-4        1165518864     14256010      -98.78%

Change-Id: I652b3244bd074a03f3bc9a87c282330f9e5f1507
Reviewed-on: https://go-review.googlesource.com/21506
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

math/big: add s390x function implementations

Change-Id: I2aadc885d6330460e494c687757f07c5e006f3b0
Reviewed-on: https://go-review.googlesource.com/20937
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

sync/atomic: add s390x implementations of atomic functions

Load and store instructions are atomic on s390x.

Change-Id: I33c641a75954f4fbd301b11a467cb57872038880
Reviewed-on: https://go-review.googlesource.com/20947
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

go/types: make Identical(nil, T) == Identical(T, nil)

Fixes #15173

Change-Id: I353756f7bc36db0d2b24d40c80771481b7b18f6b
Reviewed-on: https://go-review.googlesource.com/21585
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Revert "runtime: merge lfstack{Pack,Unpack} into one file"

This broke solaris, which apparently does use the upper 17 bits of the address space.

This reverts commit 3b02c5b1b66df9cdb23d5a3243bb37b2c312ea1b.

Change-Id: Iedfe54abd0384960845468205f20191a97751c0b
Reviewed-on: https://go-review.googlesource.com/21652
Reviewed-by: Dave Cheney <dave@cheney.net>

cmd/compile: fold CMPconst and SHR

Fold the comparison when the SHR result is small.

Useful for:
- murmur mix like hashing where higher bits are desirable, i.e. hash = uint32(i * C) >> 18
- integer log2 via DeBruijn sequence: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogDeBruijn

Change-Id: If70ae18cb86f4cc83ab6213f88ced03cc4986156
Reviewed-on: https://go-review.googlesource.com/21514
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

runtime/pprof: make TestBlockProfile less timing dependent

The test for profiling of channel blocking is timing dependent,
and in particular the blockSelectRecvAsync case can fail on a
slow builder (plan9_arm) when many tests are run in parallel.
The child goroutine sleeps for a fixed period so the parent
can be observed to block in a select call reading from the
child; but if the OS process running the parent goroutine is
delayed long enough, the child may wake again before the
parent has reached the blocking point.  By repeating the test
three times, the likelihood of a blocking event is increased.

Fixes #15096

Change-Id: I2ddb9576a83408d06b51ded682bf8e71e53ce59e
Reviewed-on: https://go-review.googlesource.com/21604
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

runtime: merge lfstack{Pack,Unpack} into one file

Merge the remaining lfstack{Pack,Unpack} implemetations into one file.

unsafe.Sizeof(uintptr(0)) == 4 is a constant comparison so this branch
folds away at compile time.

Dmitry confirmed that the upper 17 bits of an address will be zero for a
user mode pointer, so there is no need to sign extend on amd64 during
unpack, so we can reuse the same implementation as all othe 64 bit
archs.

Change-Id: I99f589416d8b181ccde5364c9c2e78e4a5efc7f1
Reviewed-on: https://go-review.googlesource.com/21597
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

cmd/link/internal/amd64: remove empty source file

Change-Id: I2da012ed996c669db513a462f014c6f3ffa396ee
Reviewed-on: https://go-review.googlesource.com/21646
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>

cmd: extract obj's Biobuf code into new bio package

API could still be made more Go-ey.

Updates #15165.

Change-Id: I514ffceffa43c293ae5d7e5f1e9193fda0098865
Reviewed-on: https://go-review.googlesource.com/21644
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/internal/sys: change ArchFamily constants to iotas

RIP architecture characters.

Change-Id: I36f53afdc311b14b9459ff3821bd6df54a057ded
Reviewed-on: https://go-review.googlesource.com/21628
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

cmd/link: remove dependency on sys.ArchFamily values

Change-Id: I858054b72847f4f27a1ebbdaff82820a28c03743
Reviewed-on: https://go-review.googlesource.com/21627
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/compile, cmd/link: eliminate uses of ArchFamily in error messages

Two of these error messages are already dead code: cmd/compile.main
and cmd/link.main already switch on $GOARCH, ensuring it must be a
prefix of the sys.Arch.Family.

The error message about uncompiled Go source files can be just be
simplified: anyone who's manually constructing Go object file archives
probably knows what tool to use to compile Go source files.

Change-Id: Ia4a67c0a1d1158379c127c91e909226d3367f3c2
Reviewed-on: https://go-review.googlesource.com/21626
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd: add new common architecture representation

Information about CPU architectures (e.g., name, family, byte
ordering, pointer and register size) is currently redundantly
scattered around the source tree. Instead consolidate the basic
information into a single new package cmd/internal/sys.

Also, introduce new sys.I386, sys.AMD64, etc. names for the constants
'8', '6', etc. and replace most uses of the latter. The notable
exceptions are a couple of error messages that still refer to the old
char-based toolchain names and function reltype in cmd/link.

Passes toolstash/buildall.

Change-Id: I8a6f0cbd49577ec1672a98addebc45f767e36461
Reviewed-on: https://go-review.googlesource.com/21623
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

runtime: clamp OS-reported number of processors to _MaxGomaxprocs

So that all Go processes do not die on startup on a system with >256 CPUs.

I tested this by hacking osinit to set ncpu to 1000.

Updates #15131

Change-Id: I52e061a0de97be41d684dd8b748fa9087d6f1aef
Reviewed-on: https://go-review.googlesource.com/21599
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/link: generate DWARF info using symbols

This updates dwarf.go to generate debug information as symbols
instead of directly writing to the output file. This should make
it easier to move generation of some of the debug info into the compiler.

Change-Id: Id2358988bfb689865ab4d68f82716f0676336df4
Reviewed-on: https://go-review.googlesource.com/20679
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

math: add functions and stubs for s390x

Includes assembly implementations of Sqrt and Dim.

Change-Id: I57472e8d31e2ee74bcebf9f8e818f765eb9b8abf
Reviewed-on: https://go-review.googlesource.com/20936
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/compile, go/importer: minor cleanups

Change-Id: I4ffb79d8cb08b0b44f59757fb7f0ec3ed1e4479f
Reviewed-on: https://go-review.googlesource.com/21624
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

cmd/compile: move Type.Maplineno to separate data structure

Relatively few types are ever used as map keys,
so tracking this separately is a net win.

Passes toolstash -cmp.

name       old alloc/op     new alloc/op     delta
Template       55.9MB ± 0%      55.5MB ± 0%  -0.71%        (p=0.000 n=10+10)
Unicode        37.8MB ± 0%      37.7MB ± 0%  -0.27%        (p=0.000 n=10+10)
GoTypes         180MB ± 0%       179MB ± 0%  -0.52%         (p=0.000 n=7+10)
Compiler        806MB ± 0%       803MB ± 0%  -0.41%        (p=0.000 n=10+10)

CPU and number of allocs are unchanged.

Change-Id: I6d60d74a4866995a231dfed3dd5792d75d904292
Reviewed-on: https://go-review.googlesource.com/21622
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

bytes: add ContainsAny

This function is present in the strings package but missing from bytes,
and we would like to keep the two packages consistent.

Add it to bytes, and copy the test over as well.

Fixes #15140

Change-Id: I5dbd28da83a9fe741885794ed15f2af2f826cb3c
Reviewed-on: https://go-review.googlesource.com/21562
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

runtime: remove unused return value from lfstackUnpack

None of the two places that call lfstackUnpack use the second argument.
This simplifies a followup CL that merges the lfstack{Pack,Unpack}
implementations.

Change-Id: I3c93f6259da99e113d94f8c8027584da79c1ac2c
Reviewed-on: https://go-review.googlesource.com/21595
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/compile: replaces ANDQ with MOV?ZX

Where possible replace ANDQ with MOV?ZX.
Takes care that we don't regress wrt bounds checking,
for example [1000]int{}[i&255].

According to "Intel 64 and IA-32 Architectures Optimization Reference
Manual" Section: "3.5.1.13 Zero-Latency MOV Instructions"
MOV?ZX instructions have zero latency on newer processors.

Updates #15105

Change-Id: I63539fdbc5812d5563aa1ebc49eca035bd307997
Reviewed-on: https://go-review.googlesource.com/21508
Reviewed-by: Айнар Гарипов <gugl.zadolbal@gmail.com>
Reviewed-by: David Chase <drchase@google.com>

encoding/json: respect json.Marshaler when encoding byte kind slices

Fixes #13783.

Change-Id: I0122c1f0cf4075acabf5f58241bded1835699dc1
Reviewed-on: https://go-review.googlesource.com/19725
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

net, runtime: skip flaky tests on OpenBSD

Flaky tests are a distraction and cover up real problems.

File bugs instead and mark them as flaky.

This moves the net/http flaky test flagging mechanism to internal/testenv.

Updates #15156
Updates #15157
Updates #15158

Change-Id: I0e561cd2a09c0dec369cd4ed93bc5a2b40233dfe
Reviewed-on: https://go-review.googlesource.com/21614
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

cmd/compile: shrink gc.Type in half

Many of Type's fields are etype-specific.
This CL organizes them into their own auxiliary types,
duplicating a few fields as necessary,
and adds an Extra field to hold them.
It also sorts the remaining fields for better struct packing.
It also improves documentation for most fields.

This reduces the size of Type at the cost of some extra allocations.
There's no CPU impact; memory impact below.
It also makes the natural structure of Type clearer.

Passes toolstash -cmp on all architectures.

Ideas for future work in this vein:

(1) Width and Align probably only need to be
stored for Struct and Array types.
The refactoring to accomplish this would hopefully
also eliminate TFUNCARGS and TCHANARGS entirely.

(2) Maplineno is sparsely used and could probably better be
stored in a separate map[*Type]int32, with mapqueue updated
to store both a Node and a line number.

(3) The Printed field may be removable once the old (non-binary)
importer/exported has been removed.

(4) StructType's fields field could be changed from *[]*Field to []*Field,
which would remove a common allocation.

(5) I believe that Type.Nod can be moved to ForwardType. Separate CL.

name       old alloc/op     new alloc/op     delta
Template       57.9MB ± 0%      55.9MB ± 0%  -3.43%        (p=0.000 n=50+50)
Unicode        38.3MB ± 0%      37.8MB ± 0%  -1.39%        (p=0.000 n=50+50)
GoTypes         185MB ± 0%       180MB ± 0%  -2.56%        (p=0.000 n=50+50)
Compiler        824MB ± 0%       806MB ± 0%  -2.19%        (p=0.000 n=50+50)

name       old allocs/op    new allocs/op    delta
Template         486k ± 0%        497k ± 0%  +2.25%        (p=0.000 n=50+50)
Unicode          377k ± 0%        379k ± 0%  +0.55%        (p=0.000 n=50+50)
GoTypes         1.39M ± 0%       1.42M ± 0%  +1.63%        (p=0.000 n=50+50)
Compiler        5.52M ± 0%       5.57M ± 0%  +0.84%        (p=0.000 n=47+50)

Change-Id: I828488eeb74902b013d5ae4cf844de0b6c0dfc87
Reviewed-on: https://go-review.googlesource.com/21611
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

test: make goprint.go wait for goroutine termination

Test goprint.go sometimes failed on a slow builder (plan9_arm)
because of timing dependency.  Instead of sleeping for a fixed
time to allow the child goroutine to finish, wait explicitly for
child termination by calling runtime.NumGoroutine until the
returned value is 1.

Fixes #15097

Change-Id: Ib3ef5ec3c8277083c774542f48bcd4ff2f79efde
Reviewed-on: https://go-review.googlesource.com/21603
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

testing: fix flakey test on plan9

allow for more than 0.00s.

Fixes #15149

Change-Id: I1d428a9b3c9bb3d1db8682c53b86e44cecc1dde1
Reviewed-on: https://go-review.googlesource.com/21602
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/gofmt: make gofmt -s simplify slices in presence of dot-imports

A dot-import cannot possibly introduce a `len` function since that
function would not be exported (it's lowercase). Furthermore, the
existing code already (incorrectly) assumed that there was no other
`len` function in another file of the package. Since this has been
an ok assumption for years, let's leave it, but remove the dot-import
restriction.

Fixes #15153.

Change-Id: I18fbb27acc5a5668833b4b4aead0cca540862b52
Reviewed-on: https://go-review.googlesource.com/21613
Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

icmd/vet: improved checking for variadic Println-like functions

- Automatically determine the first argument to check.
- Skip checking matching non-variadic functions.
- Skip checking matching functions accepting non-interface{}
  variadic arguments.
- Removed fragile 'magic' code for special cases such as math.Log
  and error interface.

Fixes #15067
Fixes #15099

Change-Id: Ib313557f18b12b36daa493f4b02c598b9503b55b
Reviewed-on: https://go-review.googlesource.com/21513
Run-TryBot: Rob Pike <r@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

cmd/link: eliminate a bunch of open coded elf64/rela switches

We already have variables to track whether the target platform is
64-bit vs 32-bit or RELA vs REL, so no point in repeating the list of
obscure architecture characters everywhere.

Passes toolstash/buildall.

Change-Id: I6a07f74188ac592ef229a7c65848a9ba93013cdb
Reviewed-on: https://go-review.googlesource.com/21569
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

testing: fixed bug introduced by CL 21504

This broke T.Run

Change-Id: I12c8fe3612f3fa2caa83049c1c7003056daf2b0c
Reviewed-on: https://go-review.googlesource.com/21600
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

runtime: use windows.NewLazySystemDLL in mksyscall_windows.go

Change-Id: Ie4c4ff4167ee45ae93a8b764fb6197f402e7994d
Reviewed-on: https://go-review.googlesource.com/21593
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/vet: do not treat declaration as asignment in atomic check

Fixes #15118

Change-Id: Iad56ed412535c8ac0a01c4bd7769fd3d37688ac9
Reviewed-on: https://go-review.googlesource.com/21526
Run-TryBot: Rob Pike <r@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

os/user: wrap getgrnam_r to fix type issues

Even with -D_POSIX_PTHREAD_SEMANTICS, Solaris seems to not define
getgrnam_r in a POSIX compatible way.

Fixes #14967

Change-Id: I78cb7e5b30b2d8b860e336060a0a06f4720c0475
Reviewed-on: https://go-review.googlesource.com/21385
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

net/http/pprof: note calling runtime.SetBlockProfileRate is required for block profile

Fixes #15076

Change-Id: I5ce8f6253245d8cc1f862a1bf618775f557f955d
Reviewed-on: https://go-review.googlesource.com/21610
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/compile: fix x=x assignments

No point in doing anything for x=x assignments.
In addition, skipping these assignments prevents generating:
    VARDEF x
    COPY x -> x
which is bad because x is incorrectly considered
dead before the vardef.

Fixes #14904

Change-Id: I6817055ec20bcc34a9648617e0439505ee355f82
Reviewed-on: https://go-review.googlesource.com/21470
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

runtime: merge 64bit lfstack impls

Merge all the 64bit lfstack impls into one file, adjust build tags to
match.

Merge all the comments on the various lfstack implementations for
posterity.

lfstack_amd64.go can probably be merged, but it is slightly different so
that will happen in a followup.

Change-Id: I5362d5e127daa81c9cb9d4fa8a0cc5c5e5c2707c
Reviewed-on: https://go-review.googlesource.com/21591
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

os: consolidate os{1,2}_*.go files

Change-Id: I463ca59f486b2842f67f151a55f530ee10663830
Reviewed-on: https://go-review.googlesource.com/21568
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

runtime: rename os1_windows.go to os_windows.go

Change-Id: I11172f3d0e28f17b812e67a4db9cfe513b8e1974
Reviewed-on: https://go-review.googlesource.com/21565
Reviewed-by: Minux Ma <minux@golang.org>

runtime: merge os{,2}_windows.go into os1_windows.go.

A future CL will rename os1_windows.go to os_windows.go.

Change-Id: I223e76002dd1e9c9d1798fb0beac02c7d3bf4812
Reviewed-on: https://go-review.googlesource.com/21564
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

runtime: add s390x support (modified files only)

Change-Id: Ib79ad4a890994ad64edb1feb79bd242d26b5b08a
Reviewed-on: https://go-review.googlesource.com/20945
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

runtime: get randomness from AT_RANDOM AUXV on linux/arm64

Fixes #15147.

Change-Id: Ibfe46c747dea987787a51eb0c95ccd8c5f24f366
Reviewed-on: https://go-review.googlesource.com/21580
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

reflect: add s390x support

Change-Id: I1f975130179cf26af67e82664310b93d43e87a75
Reviewed-on: https://go-review.googlesource.com/20944
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

io: add ReadAtSizer interface

ReadAtSizer is a common abstraction for a stateless,
concurrently-readable fixed number of bytes.

This interface has existed in various codebases for over 3 years (previously
usually named SizeReaderAt). It is used inside Google in dl.google.com
(mentioned in https://talks.golang.org/2013/oscon-dl.slide) and other
packages. It is used in Camlistore, in Juju, in the Google API Go client, in
github.com/nightlyone/views, and 33 other pages of Github search results.

It is implemented by io.SectionReader, bytes.Reader, strings.Reader, etc.

Time to finally promote this interface to the standard library and give it a
standard name, blessing it as best practice.

Updates #7263
Updates #14889

Change-Id: Id28c0cafa7d2d37e8887c54708b5daf1b11c83ea
Reviewed-on: https://go-review.googlesource.com/21492
Reviewed-by: Rob Pike <r@golang.org>

runtime: rename os1_linux.go to os_linux.go

Change-Id: I938f61763c3256a876d62aeb54ef8c25cc4fc90e
Reviewed-on: https://go-review.googlesource.com/21567
Reviewed-by: Minux Ma <minux@golang.org>

runtime: merge os_linux.go into os1_linux.go

Change-Id: I791c47014fe69e8529c7b2f0b9a554e47902d46c
Reviewed-on: https://go-review.googlesource.com/21566
Reviewed-by: Minux Ma <minux@golang.org>

expvar: Ensure strings are written as valid JSON.

Change-Id: I5147dbf4e85cf42cd1f32c57861e4c16d9dbd049
Reviewed-on: https://go-review.googlesource.com/21529
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

net/http: keep request context during Client redirects

Change-Id: I25c51280ba55120ffeaf08222f5ac5d471632d89
Reviewed-on: https://go-review.googlesource.com/21535
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/compile: encapsulate reads of gc.Type.Funarg

Changes generated with eg and then manually
checked and in some cases simplified.

Passes toolstash -cmp.

Change-Id: I2119f37f003368ce1884d2863b406d6ffbfe38c7
Reviewed-on: https://go-review.googlesource.com/21563
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

net/http: document that Handlers shouldn't mutate Request

Also, don't read from the Request.Headers in the http Server code once
ServeHTTP has started. This is partially redundant with documenting
that handlers shouldn't mutate request, but: the space is free due to
bool packing, it's faster to do the checks once instead of N times in
writeChunk, and it's a little nicer to code which previously didn't
play by the unwritten rules. But I'm not going to fix all the cases.

Fixes #14940

Change-Id: I612a8826b41c8682b59515081c590c512ee6949e
Reviewed-on: https://go-review.googlesource.com/21530
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

runtime: minor Windows cleanup

Change-Id: I9a8081ef1109469e9577c642156aa635188d8954
Reviewed-on: https://go-review.googlesource.com/21538
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

net/http, net/http/httputil: start with capitals in deprecation sentences

Fixes #15139

Change-Id: I73111137907e612af871b77ccf166572bf78c840
Reviewed-on: https://go-review.googlesource.com/21544
Reviewed-by: Andrew Gerrand <adg@golang.org>

cmd/compile: move a lot of declarations outside of go.go

go.go is currently a grab bag of various unrelated type and variable
declarations. Move a bunch of them into other more relevant source
files.

There are still more that can be moved, but these were the low hanging
fruit with obvious homes.

No code/comment changes. Just shuffling stuff around.

Change-Id: I43dbe1a5b8b707709c1a3a034c693d38b8465063
Reviewed-on: https://go-review.googlesource.com/21561
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/compile: add comments explaining how declarations/scopes work

Change-Id: I301760b015eb69ff12eee53473fdbf5e9f168413
Reviewed-on: https://go-review.googlesource.com/21542
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

crypto/rsa, crypto/ecdsa: fail earlier on zero parameters

Change-Id: Ia6ed49d5ef3a256a55e6d4eaa1b4d9f0fc447013
Reviewed-on: https://go-review.googlesource.com/21560
Reviewed-by: Robert Griesemer <gri@golang.org>

testing: improve output

This introduces a few changes
- Skipped benchmarks now print a SKIP line, also if there was
no output
- The benchmark name is only printed if there the benchmark
was not skipped or did not fail in the probe phase.

It also fixes a bug of doubling a skip message in chatty mode in
absense of a failure.

The chatty flag is now passed in the common struct to allow
for testing of the printed messages.

Fixes #14799

Change-Id: Ia8eb140c2e5bb467e66b8ef20a2f98f5d95415d5
Reviewed-on: https://go-review.googlesource.com/21504
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

cmd/compile: pull ssa OAPPEND expression handing into its own function

Pure code movement.

Change-Id: Ia07ee0b0041c931b08adf090f262a6f74a6fdb01
Reviewed-on: https://go-review.googlesource.com/21546
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/compile: give TLS relocations a name when dumping assembly

Before:

...
0x00d0 ff ff ff e8 00 00 00 00 e9 23 ff ff ff cc cc cc  .........#......
rel 5+4 t=14 +0
rel 82+4 t=13 runtime.writeBarrier+0
...

After:

...
0x00d0 ff ff ff e8 00 00 00 00 e9 23 ff ff ff cc cc cc  .........#......
rel 5+4 t=14 TLS+0
rel 82+4 t=13 runtime.writeBarrier+0
...

Change-Id: Ibdaf694581b5fd5fb87fa8ce6a792f3eb4493622
Reviewed-on: https://go-review.googlesource.com/21545
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

os: deprecate os.SEEK_SET, os.SEEK_CUR, and os.SEEK_END

CL/19862 introduced the same set of constants to the io package.
We should steer users away from the os.SEEK* versions and towards
the io.Seek* versions.

Updates #6885

Change-Id: I96ec5be3ec3439e1295c937159dadaf1ebfb2737
Reviewed-on: https://go-review.googlesource.com/21540
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

go/importer: match predeclared type list with gc's list in binary exporter

I think we had this code before but it may have gone lost somehow.

Change-Id: Ifde490e686de0d2bfe907cbe19c9197f24f5fa8e
Reviewed-on: https://go-review.googlesource.com/21537
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

cmd/compile: note escape of parts of closured-capture vars

Missed a case for closure calls (OCALLFUNC && indirect) in
esc.go:esccall.

Cleanup to runtime code for windows to more thoroughly hide
a technical escape.  Also made code pickier about failing
to late non-optional kernel32.dll.

Fixes #14409.

Change-Id: Ie75486a2c8626c4583224e02e4872c2875f7bca5
Reviewed-on: https://go-review.googlesource.com/20102
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

crypto/dsa: eliminate invalid PublicKey early

For PublicKey.P == 0, Verify will fail. Don't even try.

Change-Id: I1009f2b3dead8d0041626c946633acb10086d8c8
Reviewed-on: https://go-review.googlesource.com/21533
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

doc: add httptest.ResponseRecorder note to go1.7.txt notes

Fixes #14928

Change-Id: Id772eb623815cb2bb3e49de68a916762345a9dc1
Reviewed-on: https://go-review.googlesource.com/21531
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

runtime: don't burn CPU unnecessarily

Two GC-related functions, scang and casgstatus, wait in an active spin loop.
Active spinning is never a good idea in user-space. Once we wait several
times more than the expected wait time, something unexpected is happenning
(e.g. the thread we are waiting for is descheduled or handling a page fault)
and we need to yield to OS scheduler. Moreover, the expected wait time is
very high for these functions: scang wait time can be tens of milliseconds,
casgstatus can be hundreds of microseconds. It does not make sense to spin
even for that time.

go install -a std profile on a 4-core machine shows that 11% of time is spent
in the active spin in scang:

  6.12%    compile  compile                [.] runtime.scang
  3.27%    compile  compile                [.] runtime.readgstatus
  1.72%    compile  compile                [.] runtime/internal/atomic.Load

The active spin also increases tail latency in the case of the slightest
oversubscription: GC goroutines spend whole quantum in the loop instead of
executing user code.

Here is scang wait time histogram during go install -a std:

13707.0000 - 1815442.7667 [   118]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎...
1815442.7667 - 3617178.5333 [     9]: ∎∎∎∎∎∎∎∎∎
3617178.5333 - 5418914.3000 [    11]: ∎∎∎∎∎∎∎∎∎∎∎
5418914.3000 - 7220650.0667 [     5]: ∎∎∎∎∎
7220650.0667 - 9022385.8333 [    12]: ∎∎∎∎∎∎∎∎∎∎∎∎
9022385.8333 - 10824121.6000 [    13]: ∎∎∎∎∎∎∎∎∎∎∎∎∎
10824121.6000 - 12625857.3667 [    15]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
12625857.3667 - 14427593.1333 [    18]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
14427593.1333 - 16229328.9000 [    18]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
16229328.9000 - 18031064.6667 [    32]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
18031064.6667 - 19832800.4333 [    28]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
19832800.4333 - 21634536.2000 [     6]: ∎∎∎∎∎∎
21634536.2000 - 23436271.9667 [    15]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
23436271.9667 - 25238007.7333 [    11]: ∎∎∎∎∎∎∎∎∎∎∎
25238007.7333 - 27039743.5000 [    27]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
27039743.5000 - 28841479.2667 [    20]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
28841479.2667 - 30643215.0333 [    10]: ∎∎∎∎∎∎∎∎∎∎
30643215.0333 - 32444950.8000 [     7]: ∎∎∎∎∎∎∎
32444950.8000 - 34246686.5667 [     4]: ∎∎∎∎
34246686.5667 - 36048422.3333 [     4]: ∎∎∎∎
36048422.3333 - 37850158.1000 [     1]: ∎
37850158.1000 - 39651893.8667 [     5]: ∎∎∎∎∎
39651893.8667 - 41453629.6333 [     2]: ∎∎
41453629.6333 - 43255365.4000 [     2]: ∎∎
43255365.4000 - 45057101.1667 [     2]: ∎∎
45057101.1667 - 46858836.9333 [     1]: ∎
46858836.9333 - 48660572.7000 [     2]: ∎∎
48660572.7000 - 50462308.4667 [     3]: ∎∎∎
50462308.4667 - 52264044.2333 [     2]: ∎∎
52264044.2333 - 54065780.0000 [     2]: ∎∎

and the zoomed-in first part:

13707.0000 - 19916.7667 [     2]: ∎∎
19916.7667 - 26126.5333 [     2]: ∎∎
26126.5333 - 32336.3000 [     9]: ∎∎∎∎∎∎∎∎∎
32336.3000 - 38546.0667 [     8]: ∎∎∎∎∎∎∎∎
38546.0667 - 44755.8333 [    12]: ∎∎∎∎∎∎∎∎∎∎∎∎
44755.8333 - 50965.6000 [    10]: ∎∎∎∎∎∎∎∎∎∎
50965.6000 - 57175.3667 [     5]: ∎∎∎∎∎
57175.3667 - 63385.1333 [     6]: ∎∎∎∎∎∎
63385.1333 - 69594.9000 [     5]: ∎∎∎∎∎
69594.9000 - 75804.6667 [     6]: ∎∎∎∎∎∎
75804.6667 - 82014.4333 [     6]: ∎∎∎∎∎∎
82014.4333 - 88224.2000 [     4]: ∎∎∎∎
88224.2000 - 94433.9667 [     1]: ∎
94433.9667 - 100643.7333 [     1]: ∎
100643.7333 - 106853.5000 [     2]: ∎∎
106853.5000 - 113063.2667 [     0]:
113063.2667 - 119273.0333 [     2]: ∎∎
119273.0333 - 125482.8000 [     2]: ∎∎
125482.8000 - 131692.5667 [     1]: ∎
131692.5667 - 137902.3333 [     1]: ∎
137902.3333 - 144112.1000 [     0]:
144112.1000 - 150321.8667 [     2]: ∎∎
150321.8667 - 156531.6333 [     1]: ∎
156531.6333 - 162741.4000 [     1]: ∎
162741.4000 - 168951.1667 [     0]:
168951.1667 - 175160.9333 [     0]:
175160.9333 - 181370.7000 [     1]: ∎
181370.7000 - 187580.4667 [     1]: ∎
187580.4667 - 193790.2333 [     2]: ∎∎
193790.2333 - 200000.0000 [     0]:

Here is casgstatus wait time histogram:

  631.0000 -  5276.6333 [     3]: ∎∎∎
 5276.6333 -  9922.2667 [     5]: ∎∎∎∎∎
 9922.2667 - 14567.9000 [     2]: ∎∎
14567.9000 - 19213.5333 [     6]: ∎∎∎∎∎∎
19213.5333 - 23859.1667 [     5]: ∎∎∎∎∎
23859.1667 - 28504.8000 [     6]: ∎∎∎∎∎∎
28504.8000 - 33150.4333 [     6]: ∎∎∎∎∎∎
33150.4333 - 37796.0667 [     2]: ∎∎
37796.0667 - 42441.7000 [     1]: ∎
42441.7000 - 47087.3333 [     3]: ∎∎∎
47087.3333 - 51732.9667 [     0]:
51732.9667 - 56378.6000 [     1]: ∎
56378.6000 - 61024.2333 [     0]:
61024.2333 - 65669.8667 [     0]:
65669.8667 - 70315.5000 [     0]:
70315.5000 - 74961.1333 [     1]: ∎
74961.1333 - 79606.7667 [     0]:
79606.7667 - 84252.4000 [     0]:
84252.4000 - 88898.0333 [     0]:
88898.0333 - 93543.6667 [     0]:
93543.6667 - 98189.3000 [     0]:
98189.3000 - 102834.9333 [     0]:
102834.9333 - 107480.5667 [     1]: ∎
107480.5667 - 112126.2000 [     0]:
112126.2000 - 116771.8333 [     0]:
116771.8333 - 121417.4667 [     0]:
121417.4667 - 126063.1000 [     0]:
126063.1000 - 130708.7333 [     0]:
130708.7333 - 135354.3667 [     0]:
135354.3667 - 140000.0000 [     1]: ∎

Ideally we eliminate the waiting by switching to async
state machine for GC, but for now just yield to OS scheduler
after a reasonable wait time.

To choose yielding parameters I've measured
golang.org/x/benchmarks/http tail latencies with different yield
delays and oversubscription levels.

With no oversubscription (to the degree possible):

scang yield delay = 1, casgstatus yield delay = 1
Latency-50   1.41ms ±15%  1.41ms ± 5%    ~     (p=0.611 n=13+12)
Latency-95   5.21ms ± 2%  5.15ms ± 2%  -1.15%  (p=0.012 n=13+13)
Latency-99   7.16ms ± 2%  7.05ms ± 2%  -1.54%  (p=0.002 n=13+13)
Latency-999  10.7ms ± 9%  10.2ms ±10%  -5.46%  (p=0.004 n=12+13)

scang yield delay = 5000, casgstatus yield delay = 3000
Latency-50   1.41ms ±15%  1.41ms ± 8%    ~     (p=0.511 n=13+13)
Latency-95   5.21ms ± 2%  5.14ms ± 2%  -1.23%  (p=0.006 n=13+13)
Latency-99   7.16ms ± 2%  7.02ms ± 2%  -1.94%  (p=0.000 n=13+13)
Latency-999  10.7ms ± 9%  10.1ms ± 8%  -6.14%  (p=0.000 n=12+13)

scang yield delay = 10000, casgstatus yield delay = 5000
Latency-50   1.41ms ±15%  1.45ms ± 6%    ~     (p=0.724 n=13+13)
Latency-95   5.21ms ± 2%  5.18ms ± 1%    ~     (p=0.287 n=13+13)
Latency-99   7.16ms ± 2%  7.05ms ± 2%  -1.64%  (p=0.002 n=13+13)
Latency-999  10.7ms ± 9%  10.0ms ± 5%  -6.72%  (p=0.000 n=12+13)

scang yield delay = 30000, casgstatus yield delay = 10000
Latency-50   1.41ms ±15%  1.51ms ± 7%  +6.57%  (p=0.002 n=13+13)
Latency-95   5.21ms ± 2%  5.21ms ± 2%    ~     (p=0.960 n=13+13)
Latency-99   7.16ms ± 2%  7.06ms ± 2%  -1.50%  (p=0.012 n=13+13)
Latency-999  10.7ms ± 9%  10.0ms ± 6%  -6.49%  (p=0.000 n=12+13)

scang yield delay = 100000, casgstatus yield delay = 50000
Latency-50   1.41ms ±15%  1.53ms ± 6%  +8.48%  (p=0.000 n=13+12)
Latency-95   5.21ms ± 2%  5.23ms ± 2%    ~     (p=0.287 n=13+13)
Latency-99   7.16ms ± 2%  7.08ms ± 2%  -1.21%  (p=0.004 n=13+13)
Latency-999  10.7ms ± 9%   9.9ms ± 3%  -7.99%  (p=0.000 n=12+12)

scang yield delay = 200000, casgstatus yield delay = 100000
Latency-50   1.41ms ±15%  1.47ms ± 5%    ~     (p=0.072 n=13+13)
Latency-95   5.21ms ± 2%  5.17ms ± 2%    ~     (p=0.091 n=13+13)
Latency-99   7.16ms ± 2%  7.02ms ± 2%  -1.99%  (p=0.000 n=13+13)
Latency-999  10.7ms ± 9%   9.9ms ± 5%  -7.86%  (p=0.000 n=12+13)

With slight oversubscription (another instance of http benchmark
was running in background with reduced GOMAXPROCS):

scang yield delay = 1, casgstatus yield delay = 1
Latency-50    840µs ± 3%   804µs ± 3%  -4.37%  (p=0.000 n=15+18)
Latency-95   6.52ms ± 4%  6.03ms ± 4%  -7.51%  (p=0.000 n=18+18)
Latency-99   10.8ms ± 7%  10.0ms ± 4%  -7.33%  (p=0.000 n=18+14)
Latency-999  18.0ms ± 9%  16.8ms ± 7%  -6.84%  (p=0.000 n=18+18)

scang yield delay = 5000, casgstatus yield delay = 3000
Latency-50    840µs ± 3%   809µs ± 3%  -3.71%  (p=0.000 n=15+17)
Latency-95   6.52ms ± 4%  6.11ms ± 4%  -6.29%  (p=0.000 n=18+18)
Latency-99   10.8ms ± 7%   9.9ms ± 6%  -7.55%  (p=0.000 n=18+18)
Latency-999  18.0ms ± 9%  16.5ms ±11%  -8.49%  (p=0.000 n=18+18)

scang yield delay = 10000, casgstatus yield delay = 5000
Latency-50    840µs ± 3%   823µs ± 5%  -2.06%  (p=0.002 n=15+18)
Latency-95   6.52ms ± 4%  6.32ms ± 3%  -3.05%  (p=0.000 n=18+18)
Latency-99   10.8ms ± 7%  10.2ms ± 4%  -5.22%  (p=0.000 n=18+18)
Latency-999  18.0ms ± 9%  16.7ms ±10%  -7.09%  (p=0.000 n=18+18)

scang yield delay = 30000, casgstatus yield delay = 10000
Latency-50    840µs ± 3%   836µs ± 5%    ~     (p=0.442 n=15+18)
Latency-95   6.52ms ± 4%  6.39ms ± 3%  -2.00%  (p=0.000 n=18+18)
Latency-99   10.8ms ± 7%  10.2ms ± 6%  -5.15%  (p=0.000 n=18+17)
Latency-999  18.0ms ± 9%  16.6ms ± 8%  -7.48%  (p=0.000 n=18+18)

scang yield delay = 100000, casgstatus yield delay = 50000
Latency-50    840µs ± 3%   836µs ± 6%    ~     (p=0.401 n=15+18)
Latency-95   6.52ms ± 4%  6.40ms ± 4%  -1.79%  (p=0.010 n=18+18)
Latency-99   10.8ms ± 7%  10.2ms ± 5%  -4.95%  (p=0.000 n=18+18)
Latency-999  18.0ms ± 9%  16.5ms ±14%  -8.17%  (p=0.000 n=18+18)

scang yield delay = 200000, casgstatus yield delay = 100000
Latency-50    840µs ± 3%   828µs ± 2%  -1.49%  (p=0.001 n=15+17)
Latency-95   6.52ms ± 4%  6.38ms ± 4%  -2.04%  (p=0.001 n=18+18)
Latency-99   10.8ms ± 7%  10.2ms ± 4%  -4.77%  (p=0.000 n=18+18)
Latency-999  18.0ms ± 9%  16.9ms ± 9%  -6.23%  (p=0.000 n=18+18)

With significant oversubscription (background http benchmark
was running with full GOMAXPROCS):

scang yield delay = 1, casgstatus yield delay = 1
Latency-50   1.32ms ±12%  1.30ms ±13%    ~     (p=0.454 n=14+14)
Latency-95   16.3ms ±10%  15.3ms ± 7%  -6.29%  (p=0.001 n=14+14)
Latency-99   29.4ms ±10%  27.9ms ± 5%  -5.04%  (p=0.001 n=14+12)
Latency-999  49.9ms ±19%  45.9ms ± 5%  -8.00%  (p=0.008 n=14+13)

scang yield delay = 5000, casgstatus yield delay = 3000
Latency-50   1.32ms ±12%  1.29ms ± 9%    ~     (p=0.227 n=14+14)
Latency-95   16.3ms ±10%  15.4ms ± 5%  -5.27%  (p=0.002 n=14+14)
Latency-99   29.4ms ±10%  27.9ms ± 6%  -5.16%  (p=0.001 n=14+14)
Latency-999  49.9ms ±19%  46.8ms ± 8%  -6.21%  (p=0.050 n=14+14)

scang yield delay = 10000, casgstatus yield delay = 5000
Latency-50   1.32ms ±12%  1.35ms ± 9%     ~     (p=0.401 n=14+14)
Latency-95   16.3ms ±10%  15.0ms ± 4%   -7.67%  (p=0.000 n=14+14)
Latency-99   29.4ms ±10%  27.4ms ± 5%   -6.98%  (p=0.000 n=14+14)
Latency-999  49.9ms ±19%  44.7ms ± 5%  -10.56%  (p=0.000 n=14+11)

scang yield delay = 30000, casgstatus yield delay = 10000
Latency-50   1.32ms ±12%  1.36ms ±10%     ~     (p=0.246 n=14+14)
Latency-95   16.3ms ±10%  14.9ms ± 5%   -8.31%  (p=0.000 n=14+14)
Latency-99   29.4ms ±10%  27.4ms ± 7%   -6.70%  (p=0.000 n=14+14)
Latency-999  49.9ms ±19%  44.9ms ±15%  -10.13%  (p=0.003 n=14+14)

scang yield delay = 100000, casgstatus yield delay = 50000
Latency-50   1.32ms ±12%  1.41ms ± 9%  +6.37%  (p=0.008 n=14+13)
Latency-95   16.3ms ±10%  15.1ms ± 8%  -7.45%  (p=0.000 n=14+14)
Latency-99   29.4ms ±10%  27.5ms ±12%  -6.67%  (p=0.002 n=14+14)
Latency-999  49.9ms ±19%  45.9ms ±16%  -8.06%  (p=0.019 n=14+14)

scang yield delay = 200000, casgstatus yield delay = 100000
Latency-50   1.32ms ±12%  1.42ms ±10%   +7.21%  (p=0.003 n=14+14)
Latency-95   16.3ms ±10%  15.0ms ± 7%   -7.59%  (p=0.000 n=14+14)
Latency-99   29.4ms ±10%  27.3ms ± 8%   -7.20%  (p=0.000 n=14+14)
Latency-999  49.9ms ±19%  44.8ms ± 8%  -10.21%  (p=0.001 n=14+13)

All numbers are on 8 cores and with GOGC=10 (http benchmark has
tiny heap, few goroutines and low allocation rate, so by default
GC barely affects tail latency).

10us/5us yield delays seem to provide a reasonable compromise
and give 5-10% tail latency reduction. That's what used in this change.

go install -a std results on 4 core machine:

name      old time/op  new time/op  delta
Time       8.39s ± 2%   7.94s ± 2%  -5.34%  (p=0.000 n=47+49)
UserTime   24.6s ± 2%   22.9s ± 2%  -6.76%  (p=0.000 n=49+49)
SysTime    1.77s ± 9%   1.89s ±11%  +7.00%  (p=0.000 n=49+49)
CpuLoad    315ns ± 2%   313ns ± 1%  -0.59%  (p=0.000 n=49+48) # %CPU
MaxRSS    97.1ms ± 4%  97.5ms ± 9%    ~     (p=0.838 n=46+49) # bytes

Update #14396
Update #14189

Change-Id: I3f4109bf8f7fd79b39c466576690a778232055a2
Reviewed-on: https://go-review.googlesource.com/21503
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

runtime: sleep less when we can do work

Usleep(100) in runqgrab negatively affects latency and throughput
of parallel application. We are sleeping instead of doing useful work.
This is effect is particularly visible on windows where minimal
sleep duration is 1-15ms.

Reduce sleep from 100us to 3us and use osyield on windows.
Sync chan send/recv takes ~50ns, so 3us gives us ~50x overshoot.

benchmark                    old ns/op     new ns/op     delta
BenchmarkChanSync-12         216           217           +0.46%
BenchmarkChanSyncWork-12     27213         25816         -5.13%

CPU consumption goes up from 106% to 108% in the first case,
and from 107% to 125% in the second case.

Test case from #14790 on windows:

BenchmarkDefaultResolution-8  4583372   29720    -99.35%
Benchmark1ms-8                992056    30701    -96.91%

99-th latency percentile for HTTP request serving is improved by up to 15%
(see http://golang.org/cl/20835 for details).

The following benchmarks are from the change that originally added this sleep
(see https://golang.org/s/go15gomaxprocs):

name        old time/op  new time/op  delta
Chain       22.6µs ± 2%  22.7µs ± 6%    ~      (p=0.905 n=9+10)
ChainBuf    22.4µs ± 3%  22.5µs ± 4%    ~      (p=0.780 n=9+10)
Chain-2     23.5µs ± 4%  24.9µs ± 1%  +5.66%   (p=0.000 n=10+9)
ChainBuf-2  23.7µs ± 1%  24.4µs ± 1%  +3.31%   (p=0.000 n=9+10)
Chain-4     24.2µs ± 2%  25.1µs ± 3%  +3.70%   (p=0.000 n=9+10)
ChainBuf-4  24.4µs ± 5%  25.0µs ± 2%  +2.37%  (p=0.023 n=10+10)
Powser       2.37s ± 1%   2.37s ± 1%    ~       (p=0.423 n=8+9)
Powser-2     2.48s ± 2%   2.57s ± 2%  +3.74%   (p=0.000 n=10+9)
Powser-4     2.66s ± 1%   2.75s ± 1%  +3.40%  (p=0.000 n=10+10)
Sieve        13.3s ± 2%   13.3s ± 2%    ~      (p=1.000 n=10+9)
Sieve-2      7.00s ± 2%   7.44s ±16%    ~      (p=0.408 n=8+10)
Sieve-4      4.13s ±21%   3.85s ±22%    ~       (p=0.113 n=9+9)

Fixes #14790

Change-Id: Ie7c6a1c4f9c8eb2f5d65ab127a3845386d6f8b5d
Reviewed-on: https://go-review.googlesource.com/20835
Reviewed-by: Austin Clements <austin@google.com>

cmd/compile/internal/amd64: Use 32-bit operands for byte operations

We already generate ADDL for byte operations, reflect this in code.
This also allows inc/dec for +-1 operation, which are 1-byte shorter,
and enables lea for 3-operand addition/subtraction.

Change-Id: Ibfdfee50667ca4cd3c28f72e3dece0c6d114d3ae
Reviewed-on: https://go-review.googlesource.com/21251
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

encoding/json: allow non-string type keys for (un-)marshal

This CL allows JSON-encoding & -decoding maps whose keys are types that
implement encoding.TextMarshaler / TextUnmarshaler.

During encode, the map keys are marshaled upfront so that they can be
sorted.

Fixes #12146

Change-Id: I43809750a7ad82a3603662f095c7baf75fd172da
Reviewed-on: https://go-review.googlesource.com/20356
Run-TryBot: Caleb Spare <cespare@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

io: define SeekStart, SeekCurrent, SeekEnd constants for use with Seeker

Fixes #6885

Change-Id: I6907958186f6a2427da1ad2f6c20bd5d7bf7a3f9
Reviewed-on: https://go-review.googlesource.com/19862
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/compile: add a pass to print bound checks

Since BCE happens over several passes (opt, loopbce, prove)
it's easy to regress especially with rewriting.

The pass is only activated with special debug flag.

Change-Id: I46205982e7a2751156db8e875d69af6138068f59
Reviewed-on: https://go-review.googlesource.com/21510
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

net/http: zero pad Response status codes to three digits

Go 1.6's HTTP/1.x Transport started enforcing that responses have 3
status digits, per the spec, but we could still write out invalid
status codes ourselves if the called
ResponseWriter.WriteHeader(0). That is bogus anyway, since the minimum
status code is 1xx, but be a little bit less bogus (and consistent)
and zero pad our responses.

Change-Id: I6883901fd95073cb72f6b74035cabf1a79c35e1c
Reviewed-on: https://go-review.googlesource.com/19130
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>