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Commit Graph

31595 Commits

Author SHA1 Message Date
Josh Bleecher Snyder
2774085bdc cmd/vet/all: update windows whitelist
A last-minute rollback of a change left some
unreachable code that we don't want to remove.

Change-Id: Ida0af5b18ed1a2e13ef66c303694afcc49d7bff4
Reviewed-on: https://go-review.googlesource.com/37304
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-21 18:42:16 +00:00
Josh Bleecher Snyder
b6e0d4647f runtime: update assembly var names after monotonic time changes
Change-Id: I721045120a4df41462c02252e2e5e8529ae2d694
Reviewed-on: https://go-review.googlesource.com/37303
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-21 18:42:05 +00:00
Josh Bleecher Snyder
ea52f4b374 cmd/vet/all: update whitelists for monotonic time changes
Change-Id: Ib942cb9e0cb20821aea4274bc3ddc83a215afbcb
Reviewed-on: https://go-review.googlesource.com/37302
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-21 18:41:56 +00:00
Josh Bleecher Snyder
84a855e547 cmd/vet/all: add mips and mipsle
Change-Id: I689b2e8e214561350f88fa4e20c8f34cf69dc6a7
Reviewed-on: https://go-review.googlesource.com/37301
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-21 18:41:47 +00:00
Josh Bleecher Snyder
8ccd007f24 cmd/vet/all: work around vet printf checker deficiencies
cmd/vet has a known deficiency in its handling of fmt.Formatters.
This causes a spurious printf error only for non-host platforms.
Since cmd/vet/all may get run on any given platform,
whitelists cannot help here.

Work around the issue by skipping printf tests entirely
for non-host platforms.

Work around the one known acceptable false positive from vet
by whitelisting the file that contains it.

Change-Id: Id74b3d4db0519cf9a670a065683715f856266e45
Reviewed-on: https://go-review.googlesource.com/36936
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-21 18:41:38 +00:00
Ian Lance Taylor
35ffca31b1 os/exec: deflake TestStdinCloseRace
Stop reporting errors from cmd.Process.Kill; they don't matter for
purposes of this test, and they can occur if the process exits quickly.

Fixes #19211.
Fixes #19213.

Change-Id: I1a0bb9170220ca69199abb8e8811b1dde43e1897
Reviewed-on: https://go-review.googlesource.com/37309
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-21 17:12:57 +00:00
Cherry Zhang
a355639c60 cmd/compile: fix storeOrder
storeOrder visits values in DFS order. It should "break" after
pushing one argument to stack, instead of "continue".

Fixes #19179.

Change-Id: I561afb44213df40ebf8bf7d28e0fd00f22a81ac0
Reviewed-on: https://go-review.googlesource.com/37250
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
2017-02-21 16:29:12 +00:00
Alex Brainman
b32170abdf cmd/link: simplify peemitreloc
No functional changes.

For #10776.

Change-Id: If9a5ef832af116c5802b06a38e0c050d7363f2d5
Reviewed-on: https://go-review.googlesource.com/36981
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-21 06:11:39 +00:00
Alex Brainman
d0a978f5b5 cmd/link: reorder pe sections
dwarf writing code assumes that dwarf sections follow
.data and .bss, not .ctors. Make pe section writing code
match that assumption.

For #10776.

Change-Id: I128c3ad125f7d0db19e922f165704a054b2af7ba
Reviewed-on: https://go-review.googlesource.com/36980
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-21 06:11:17 +00:00
Alex Brainman
6db4d92e4c cmd/link: do not add __image_base__ and _image_base__ if external linker
The symbols get in a way when using external linker. They are
not associated with a section. And linker fails when
generating relocations for them.

__image_base__ and _image_base__ have been added long time ago.
I do not think they are needed anymore. If I delete them, all
tests still PASS. I tried going back to the commit that added
them to see if I can reproduce original error, but I cannot
build it. I don't have hg version of go repo, and my gcc is
complaining about cc source code.

I wasted too much time with this, so I decided to leave them only
for internal linker. That is what they were originally added for.

For #10776.

Change-Id: Ibb72b04f3864947c782f964a7badc69f4b074e25
Reviewed-on: https://go-review.googlesource.com/36979
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-21 06:10:51 +00:00
Alex Brainman
b660a4b04d cmd/link: add all pe section names to pe symbol table
dwarf relocations refer to dwarf section symbols, so dwarf
section symbols must be present in pe symbol table before we
write dwarf relocations.

.ctors pe section already refer to .text symbol.

Write all pe section name symbols into symbol table, so we
can use them whenever we need them.

This CL also simplified some code.

For #10776.

Change-Id: I9b8c680ea75904af90c797a06bbb1f4df19e34b6
Reviewed-on: https://go-review.googlesource.com/36978
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-21 05:52:04 +00:00
Alex Brainman
e9abf1a716 cmd/link: introduce shNames
Introduce a slice that keeps long pe section names as we add them.
It will be used later to output pe symbol table and dwarf relocations.

For #10776.

Change-Id: I02f808a456393659db2354031baf1d4f9e0b2d61
Reviewed-on: https://go-review.googlesource.com/36977
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-21 05:41:43 +00:00
Alex Brainman
a7e2556255 cmd/link: set VirtualAddress to 0 for external linker
This is what gcc does when it generates object files.
And pecoff.doc says: "for simplicity, compilers should
 set this to zero". It is easier to count everything,
when it starts from 0. Make go linker do the same.

For #10776.

Change-Id: Iffa4b3ad86160624ed34adf1c6ba13feba34c658
Reviewed-on: https://go-review.googlesource.com/36976
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-21 01:05:55 +00:00
Brad Fitzpatrick
a37f9d8a17 runtime/pprof: mark TestMutexProfile as flaky for now
Flaky tests hurt productivity. Disable for now.

Updates #19139

Change-Id: I2e3040bdf0e53597a1c4f925b788e3268ea284c1
Reviewed-on: https://go-review.googlesource.com/37291
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Peter Weinberger <pjw@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-20 20:17:16 +00:00
David Lazar
b9574f46f9 cmd/objdump: make test independent of inlining
Fixes #19189.

Change-Id: Ice69216c7fc2eaeb3dbbdcd08a8284204c7f52ef
Reviewed-on: https://go-review.googlesource.com/37237
Run-TryBot: David Lazar <lazard@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-02-19 21:27:16 +00:00
Martin Möhrmann
3892d50796 cmd/compile: remove unused constant divide strength reduction code
Change list https://golang.org/cl/37015/ moved the optimization
of division by constants to the generic ssa backend.
This removes the old now unused code that was used
for this optimization outside of the ssa backend.

Change-Id: I86223e56742e48dbb372ba8d779681e66448c513
Reviewed-on: https://go-review.googlesource.com/37198
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
2017-02-19 19:11:45 +00:00
Robert Griesemer
177dfba112 math/bits: faster OnesCount
Using some additional suggestions per "Hacker's Delight".
Added documentation and extra tests.

Measured on 1.7 GHz Intel Core i7, running macOS 10.12.3.

benchmark                  old ns/op     new ns/op     delta
BenchmarkOnesCount-4       7.34          5.38          -26.70%
BenchmarkOnesCount8-4      2.03          1.98          -2.46%
BenchmarkOnesCount16-4     2.56          2.50          -2.34%
BenchmarkOnesCount32-4     2.98          2.39          -19.80%
BenchmarkOnesCount64-4     4.22          2.96          -29.86%

Change-Id: I566b0ef766e55cf5776b1662b6016024ebe5d878
Reviewed-on: https://go-review.googlesource.com/37223
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-19 18:50:48 +00:00
Martin Möhrmann
d9a19f86fb fmt: remove unused global variable byteType
Change list https://golang.org/cl/20686/ removed the last use
of the variable byteType.

Change-Id: I4ea79095136a49a9d22767b37f48f3404da05056
Reviewed-on: https://go-review.googlesource.com/37197
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-19 18:50:46 +00:00
Keith Randall
cfb0d34992 cmd/compile: amd64, allow XCHG on stack pointers
XCHG needs to allow the stack pointer as an argument because we have a
rewrite that incorporates the address of a local variable into the
instruction.

Fixes #19184

Change-Id: Ic438e6e1946332cdce3864d15abecd41b911b2a9
Reviewed-on: https://go-review.googlesource.com/37253
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2017-02-19 17:16:01 +00:00
Jaana Burcu Dogan
f37428d8b7 cmd/go/internal/envcmd: report PKG_CONFIG after the CGO group
Before the change, `go env` reports PKG_CONFIG in between the
CGO env group:

    GOARCH="amd64"
    GOBIN=""
    GOEXE=""
    GOHOSTARCH="amd64"
    GOHOSTOS="darwin"
    GOOS="darwin"
    GOPATH="/Users/jbd"
    GORACE=""
    GOROOT="/Users/jbd/go"
    GOTOOLDIR="/Users/jbd/go/pkg/tool/darwin_amd64"
    GCCGO="gccgo"
    CC="clang"
    GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/lq/qcn67khn4_1b41_g48x3zchh005d21/T/go-build184491598=/tmp/go-build -gno-record-gcc-switches -fno-common"
    CXX="clang++"
    CGO_ENABLED="1"
    PKG_CONFIG="pkg-config"
    CGO_CFLAGS="-g -O2"
    CGO_CPPFLAGS=""
    CGO_CXXFLAGS="-g -O2"
    CGO_FFLAGS="-g -O2"
    CGO_LDFLAGS="-g -O2"

The change makes PKG_CONFIG to be reported as the final item,
and not breaking the CGO_* group apart.

Change-Id: I1e7ed6bdec83009ff118f85c9f0f7b78a67fdd76
Reviewed-on: https://go-review.googlesource.com/37228
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-19 08:04:38 +00:00
Martin Möhrmann
e97f407ec1 fmt: support sharp flag for float and complex value printing
Added an alternate form of printing floats and complex values
by specifying the sharp flag.

Output formatted using the the verbs v, e, E, f, F, g and G in
combination with the sharp flag will always include a decimal point.

The alternate form specified by the sharp flag for %g and %G verbs
will not truncate trailing zeros and assume a default precision of 6.

Fixes #18857.

Change-Id: I4d776239e06d7a6a90f2d8556240a359888cb7c3
Reviewed-on: https://go-review.googlesource.com/37051
Reviewed-by: Rob Pike <r@golang.org>
2017-02-19 07:18:56 +00:00
Kenny Grant
1e69aefb7e net/url: document that Query returns only valid values
Fixes #19110

Change-Id: I291fa4ec3c61145162acd019e3f0e5dd3d7c97e9
Reviewed-on: https://go-review.googlesource.com/37194
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-18 19:01:08 +00:00
Martin Möhrmann
6cfc3b25e9 math: protect benchmarked functions from being optimized away
Add exported global variables and store the results of benchmarked
functions in them. This prevents the current compiler optimizations
from removing the instructions that are needed to compute the return
values of the benchmarked functions.

Change-Id: If8b08424e85f3796bb6dd73e761c653abbabcc5e
Reviewed-on: https://go-review.googlesource.com/37195
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-18 17:00:59 +00:00
Martin Möhrmann
6ef92b6e3b os: remove incorrect detection of O_CLOEXEC flag on darwin
The below range loop will not stop when encountering
the first '.' character in a Darwin version string like "15.6.0".

for i = range osver {
   if osver[i] != '.' {
         continue
      }
   }
}

Therefore, the condition i > 2 was always satisfied and
supportsCloseOnExec was always set to true.

Since the minimum supported version of OSX for go is currently 10.8
and O_CLOEXEC is implemented from OSX 10.7 on the detection code
can be removed and support for O_CLOEXEC is always assumed to exist.

Change-Id: Idd10094d8385dd4adebc8d7a6d9e9a8f29455867
Reviewed-on: https://go-review.googlesource.com/37193
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-18 16:14:15 +00:00
Kenny Grant
497b608fab go/doc: allow : in godoc links
The emphasize function used a complex regexp to find URLs, which
truncated some types of URL and did not match others.
This has been simplified and adjusted to allow valid punctuation
like :: or ! in the path part and :[] in the host part.
Comments were added to clarify what this regexp allows.
The path part matches query and fragment also so document this.
Removed news, telnet, wais, and prospero protocols.

Tests were added for:
 IPV6 URLs
 URLs surrounded by brackets
 URLs containing ::
 URLs containing :;!- in the path

In order to allow punctuation and yet preserve current behaviour,
URLs are not permitted to end in .,:;?! to allow the use of
normal punctuation surrounding URLs in comments.

Fixes #18139

Change-Id: I38b2d7a85fe0d171e4bf4aac420f8c2d3ced8a2f
Reviewed-on: https://go-review.googlesource.com/37192
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-18 06:35:36 +00:00
Robert Griesemer
a4a3d63dbe math/bits: added benchmarks for Leading/TrailingZeros
BenchmarkLeadingZeros-8      	200000000	         8.80 ns/op
BenchmarkLeadingZeros8-8     	200000000	         8.21 ns/op
BenchmarkLeadingZeros16-8    	200000000	         7.49 ns/op
BenchmarkLeadingZeros32-8    	200000000	         7.80 ns/op
BenchmarkLeadingZeros64-8    	200000000	         8.67 ns/op

BenchmarkTrailingZeros-8     	1000000000	         2.05 ns/op
BenchmarkTrailingZeros8-8    	2000000000	         1.94 ns/op
BenchmarkTrailingZeros16-8   	2000000000	         1.94 ns/op
BenchmarkTrailingZeros32-8   	2000000000	         1.92 ns/op
BenchmarkTrailingZeros64-8   	2000000000	         2.03 ns/op

Change-Id: I45497bf2d6369ba6cfc88ded05aa735908af8908
Reviewed-on: https://go-review.googlesource.com/37220
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 23:41:16 +00:00
Robert Griesemer
19028bdd18 math/bits: faster Rotate functions, added respective benchmarks
Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.

benchmark                    old ns/op     new ns/op     delta
BenchmarkRotateLeft-8        7.87          7.00          -11.05%
BenchmarkRotateLeft8-8       8.41          4.52          -46.25%
BenchmarkRotateLeft16-8      8.07          4.55          -43.62%
BenchmarkRotateLeft32-8      8.36          4.73          -43.42%
BenchmarkRotateLeft64-8      7.93          4.78          -39.72%

BenchmarkRotateRight-8       8.23          6.72          -18.35%
BenchmarkRotateRight8-8      8.76          4.39          -49.89%
BenchmarkRotateRight16-8     9.07          4.44          -51.05%
BenchmarkRotateRight32-8     8.85          4.46          -49.60%
BenchmarkRotateRight64-8     8.11          4.43          -45.38%

Change-Id: I79ea1e9e6fc65f95794a91f860a911efed3aa8a1
Reviewed-on: https://go-review.googlesource.com/37219
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 23:40:45 +00:00
Robert Griesemer
a12edb8db6 math/bits: faster OnesCount, added respective benchmarks
Also: Changed Reverse/ReverseBytes implementations to use
the same (smaller) masks as OnesCount.

BenchmarkOnesCount-8          37.0          6.26          -83.08%
BenchmarkOnesCount8-8         7.24          1.99          -72.51%
BenchmarkOnesCount16-8        11.3          2.47          -78.14%
BenchmarkOnesCount32-8        18.4          3.02          -83.59%
BenchmarkOnesCount64-8        40.0          3.78          -90.55%
BenchmarkReverse-8            6.69          6.22          -7.03%
BenchmarkReverse8-8           1.64          1.64          +0.00%
BenchmarkReverse16-8          2.26          2.18          -3.54%
BenchmarkReverse32-8          2.88          2.87          -0.35%
BenchmarkReverse64-8          5.64          4.34          -23.05%
BenchmarkReverseBytes-8       2.48          2.17          -12.50%
BenchmarkReverseBytes16-8     0.63          0.95          +50.79%
BenchmarkReverseBytes32-8     1.13          1.24          +9.73%
BenchmarkReverseBytes64-8     2.50          2.16          -13.60%

OnesCount-8       37.0ns ± 0%   6.3ns ± 0%   ~             (p=1.000 n=1+1)
OnesCount8-8      7.24ns ± 0%  1.99ns ± 0%   ~             (p=1.000 n=1+1)
OnesCount16-8     11.3ns ± 0%   2.5ns ± 0%   ~             (p=1.000 n=1+1)
OnesCount32-8     18.4ns ± 0%   3.0ns ± 0%   ~             (p=1.000 n=1+1)
OnesCount64-8     40.0ns ± 0%   3.8ns ± 0%   ~             (p=1.000 n=1+1)
Reverse-8         6.69ns ± 0%  6.22ns ± 0%   ~             (p=1.000 n=1+1)
Reverse8-8        1.64ns ± 0%  1.64ns ± 0%   ~     (all samples are equal)
Reverse16-8       2.26ns ± 0%  2.18ns ± 0%   ~             (p=1.000 n=1+1)
Reverse32-8       2.88ns ± 0%  2.87ns ± 0%   ~             (p=1.000 n=1+1)
Reverse64-8       5.64ns ± 0%  4.34ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes-8    2.48ns ± 0%  2.17ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes16-8  0.63ns ± 0%  0.95ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes32-8  1.13ns ± 0%  1.24ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes64-8  2.50ns ± 0%  2.16ns ± 0%   ~             (p=1.000 n=1+1)

Change-Id: I591b0ffc83fc3a42828256b6e5030f32c64f9497
Reviewed-on: https://go-review.googlesource.com/37218
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 23:40:10 +00:00
Ilya Tocar
21c71d7788 cmd/compile/internal/ssa: combine load + op on AMD64
On AMD64 Most operation can have one operand in memory.
Combine load and dependand operation into one new operation,
where possible. I've seen no significant performance changes on go1,
but this allows to remove ~1.8kb code from go tool. And in math package
I see e. g.:

Remainder-6            70.0ns ± 0%   64.6ns ± 0%   -7.76%  (p=0.000 n=9+1
Change-Id: I88b8602b1d55da8ba548a34eb7da4b25d59a297e
Reviewed-on: https://go-review.googlesource.com/36793
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-02-17 22:21:49 +00:00
Keith Randall
a9292b833b cmd/compile: fix 32-bit unsigned division on 64-bit machines
The type of an intermediate multiply was wrong.  When that
intermediate multiply was spilled, the top 32 bits were lost.

Fixes #19153

Change-Id: Ib29350a4351efa405935b7f7ee3c112668e64108
Reviewed-on: https://go-review.googlesource.com/37212
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2017-02-17 22:21:04 +00:00
Robert Griesemer
4498b68390 math/bits: faster Reverse, ReverseBytes
- moved from: x&m>>k | x&^m<<k to: x&m>>k | x<<k&m
  This permits use of the same constant m twice (*) which may be
  better for machines that can't use large immediate constants
  directly with an AND instruction and have to load them explicitly.
  *) CPUs don't usually have a &^ instruction, so x&^m becomes x&(^m)

- simplified returns
  This improves the generated code because the compiler recognizes
  x>>k | x<<k as ROT when k is the bitsize of x.

The 8-bit versions of these instructions can be significantly faster
still if they are replaced with table lookups, as long as the table
is in cache. If the table is not in cache, table-lookup is probably
slower, hence the choice of an explicit register-only implementation
for now.

BenchmarkReverse-8            8.50          6.86          -19.29%
BenchmarkReverse8-8           2.17          1.74          -19.82%
BenchmarkReverse16-8          2.89          2.34          -19.03%
BenchmarkReverse32-8          3.55          2.95          -16.90%
BenchmarkReverse64-8          6.81          5.57          -18.21%
BenchmarkReverseBytes-8       3.49          2.48          -28.94%
BenchmarkReverseBytes16-8     0.93          0.62          -33.33%
BenchmarkReverseBytes32-8     1.55          1.13          -27.10%
BenchmarkReverseBytes64-8     2.47          2.47          +0.00%

Reverse-8         8.50ns ± 0%  6.86ns ± 0%   ~             (p=1.000 n=1+1)
Reverse8-8        2.17ns ± 0%  1.74ns ± 0%   ~             (p=1.000 n=1+1)
Reverse16-8       2.89ns ± 0%  2.34ns ± 0%   ~             (p=1.000 n=1+1)
Reverse32-8       3.55ns ± 0%  2.95ns ± 0%   ~             (p=1.000 n=1+1)
Reverse64-8       6.81ns ± 0%  5.57ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes-8    3.49ns ± 0%  2.48ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes16-8  0.93ns ± 0%  0.62ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes32-8  1.55ns ± 0%  1.13ns ± 0%   ~             (p=1.000 n=1+1)
ReverseBytes64-8  2.47ns ± 0%  2.47ns ± 0%   ~     (all samples are equal)

Change-Id: I0064de8c7e0e568ca7885d6f7064344bef91a06d
Reviewed-on: https://go-review.googlesource.com/37215
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-17 22:20:28 +00:00
Matthew Dempsky
c61cf5e6b7 cmd/compile/internal/gc: remove Node.IsStatic field
We can immediately emit static assignment data rather than queueing
them up to be processed during SSA building.

Passes toolstash -cmp.

Change-Id: I8bcea4b72eafb0cc0b849cd93e9cde9d84f30d5e
Reviewed-on: https://go-review.googlesource.com/37024
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2017-02-17 22:06:52 +00:00
Cherry Zhang
3557d54609 cmd/compile: check both syms when folding address into load/store on ARM64
The rules for folding addresses into load/stores checks sym1 is
not on stack (because the stack offset is not known at that point).
But sym1 could be nil, which invalidates the check. Check merged
sym instead.

Fixes #19137.

Change-Id: I8574da22ced1216bb5850403d8f08ec60a8d1005
Reviewed-on: https://go-review.googlesource.com/37145
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2017-02-17 21:23:24 +00:00
Robert Griesemer
3a239a6ae4 math/bits: fix benchmarks (make sure calls don't get optimized away)
Sum up function results and store them in an exported (global)
variable. This prevents the compiler from optimizing away the
otherwise side-effect free function calls.

We now have more realistic set of benchmark numbers...

Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.

Note: These measurements are based on the same "old"
implementation as the prior measurements (commit 7d5c003).

benchmark                     old ns/op     new ns/op     delta
BenchmarkReverse-8            72.9          8.50          -88.34%
BenchmarkReverse8-8           13.2          2.17          -83.56%
BenchmarkReverse16-8          21.2          2.89          -86.37%
BenchmarkReverse32-8          36.3          3.55          -90.22%
BenchmarkReverse64-8          71.3          6.81          -90.45%
BenchmarkReverseBytes-8       11.2          3.49          -68.84%
BenchmarkReverseBytes16-8     6.24          0.93          -85.10%
BenchmarkReverseBytes32-8     7.40          1.55          -79.05%
BenchmarkReverseBytes64-8     10.5          2.47          -76.48%

Reverse-8         72.9ns ± 0%   8.5ns ± 0%   ~     (p=1.000 n=1+1)
Reverse8-8        13.2ns ± 0%   2.2ns ± 0%   ~     (p=1.000 n=1+1)
Reverse16-8       21.2ns ± 0%   2.9ns ± 0%   ~     (p=1.000 n=1+1)
Reverse32-8       36.3ns ± 0%   3.5ns ± 0%   ~     (p=1.000 n=1+1)
Reverse64-8       71.3ns ± 0%   6.8ns ± 0%   ~     (p=1.000 n=1+1)
ReverseBytes-8    11.2ns ± 0%   3.5ns ± 0%   ~     (p=1.000 n=1+1)
ReverseBytes16-8  6.24ns ± 0%  0.93ns ± 0%   ~     (p=1.000 n=1+1)
ReverseBytes32-8  7.40ns ± 0%  1.55ns ± 0%   ~     (p=1.000 n=1+1)
ReverseBytes64-8  10.5ns ± 0%   2.5ns ± 0%   ~     (p=1.000 n=1+1)

Change-Id: I8aef1334b84f6cafd25edccad7e6868b37969efb
Reviewed-on: https://go-review.googlesource.com/37213
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 20:58:12 +00:00
Robert Griesemer
ddb15cea4a math/bits: much faster ReverseBytes, added respective benchmarks
Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.

benchmark                     old ns/op     new ns/op     delta
BenchmarkReverseBytes-8       11.4          3.51          -69.21%
BenchmarkReverseBytes16-8     6.87          0.64          -90.68%
BenchmarkReverseBytes32-8     7.79          0.65          -91.66%
BenchmarkReverseBytes64-8     11.6          0.64          -94.48%

name              old time/op  new time/op  delta
ReverseBytes-8    11.4ns ± 0%   3.5ns ± 0%   ~     (p=1.000 n=1+1)
ReverseBytes16-8  6.87ns ± 0%  0.64ns ± 0%   ~     (p=1.000 n=1+1)
ReverseBytes32-8  7.79ns ± 0%  0.65ns ± 0%   ~     (p=1.000 n=1+1)
ReverseBytes64-8  11.6ns ± 0%   0.6ns ± 0%   ~     (p=1.000 n=1+1)

Change-Id: I67b529652b3b613c61687e9e185e8d4ee40c51a2
Reviewed-on: https://go-review.googlesource.com/37211
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 19:38:26 +00:00
Robert Griesemer
7d5c003a3a math/bits: much faster Reverse, added respective benchmarks
Measured on 2.3 GHz Intel Core i7, running maxOS 10.12.3.

name         old time/op  new time/op  delta
Reverse-8    76.6ns ± 0%   8.1ns ± 0%   ~     (p=1.000 n=1+1)
Reverse8-8   12.6ns ± 0%   0.6ns ± 0%   ~     (p=1.000 n=1+1)
Reverse16-8  20.8ns ± 0%   0.6ns ± 0%   ~     (p=1.000 n=1+1)
Reverse32-8  36.5ns ± 0%   0.6ns ± 0%   ~     (p=1.000 n=1+1)
Reverse64-8  74.0ns ± 0%   6.4ns ± 0%   ~     (p=1.000 n=1+1)

benchmark                old ns/op     new ns/op     delta
BenchmarkReverse-8       76.6          8.07          -89.46%
BenchmarkReverse8-8      12.6          0.64          -94.92%
BenchmarkReverse16-8     20.8          0.64          -96.92%
BenchmarkReverse32-8     36.5          0.64          -98.25%
BenchmarkReverse64-8     74.0          6.38          -91.38%

Change-Id: I6b99b10cee2f2babfe79342b50ee36a45a34da30
Reviewed-on: https://go-review.googlesource.com/37149
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 19:38:13 +00:00
Cherry Zhang
c4b8dadb40 cmd/compile: fix some types in SSA
These seem not to really matter, but good to be correct.

Change-Id: I02edb9797c3d6739725cfbe4723c75f151acd05e
Reviewed-on: https://go-review.googlesource.com/36837
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2017-02-17 19:20:46 +00:00
Cherry Zhang
c4ef597c47 cmd/compile: redo writebarrier pass
SSA's writebarrier pass requires WB store ops are always at the
end of a block. If we move write barrier insertion into SSA and
emits normal Store ops when building SSA, this requirement becomes
impractical -- it will create too many blocks for all the Store
ops.

Redo SSA's writebarrier pass, explicitly order values in store
order, so it no longer needs this requirement.

Updates #17583.
Fixes #19067.

Change-Id: I66e817e526affb7e13517d4245905300a90b7170
Reviewed-on: https://go-review.googlesource.com/36834
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2017-02-17 19:20:25 +00:00
Cherry Zhang
98061fa5f3 cmd/compile: re-enable nilcheck removal in same block
Nil check removal in the same block is disabled due to issue 18725:
because the values are not ordered, a nilcheck may influence a
value that is logically before it. This CL re-enables same-block
nilcheck removal by ordering values in store order first.

Updates #18725.

Change-Id: I287a38525230c14c5412cbcdbc422547dabd54f6
Reviewed-on: https://go-review.googlesource.com/35496
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2017-02-17 19:19:59 +00:00
Robert Griesemer
81acd308a4 math/bits: expand doc strings for all functions
Follow-up on https://go-review.googlesource.com/36315.
No functionality change.

For #18616.

Change-Id: Id4df34dd7d0381be06eea483a11bf92f4a01f604
Reviewed-on: https://go-review.googlesource.com/37140
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-17 19:02:56 +00:00
Koki Ide
045ad5bab8 all: fix a few typos in comments
Change-Id: I0455ffaa51c661803d8013c7961910f920d3c3cc
Reviewed-on: https://go-review.googlesource.com/37043
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-17 18:15:41 +00:00
Dmitry Vyukov
0556e26273 sync: make Mutex more fair
Add new starvation mode for Mutex.
In starvation mode ownership is directly handed off from
unlocking goroutine to the next waiter. New arriving goroutines
don't compete for ownership.
Unfair wait time is now limited to 1ms.
Also fix a long standing bug that goroutines were requeued
at the tail of the wait queue. That lead to even more unfair
acquisition times with multiple waiters.

Performance of normal mode is not considerably affected.

Fixes #13086

On the provided in the issue lockskew program:

done in 1.207853ms
done in 1.177451ms
done in 1.184168ms
done in 1.198633ms
done in 1.185797ms
done in 1.182502ms
done in 1.316485ms
done in 1.211611ms
done in 1.182418ms

name                    old time/op  new time/op   delta
MutexUncontended-48     0.65ns ± 0%   0.65ns ± 1%     ~           (p=0.087 n=10+10)
Mutex-48                 112ns ± 1%    114ns ± 1%   +1.69%        (p=0.000 n=10+10)
MutexSlack-48            113ns ± 0%     87ns ± 1%  -22.65%         (p=0.000 n=8+10)
MutexWork-48             149ns ± 0%    145ns ± 0%   -2.48%         (p=0.000 n=9+10)
MutexWorkSlack-48        149ns ± 0%    122ns ± 3%  -18.26%         (p=0.000 n=6+10)
MutexNoSpin-48           103ns ± 4%    105ns ± 3%     ~           (p=0.089 n=10+10)
MutexSpin-48             490ns ± 4%    515ns ± 6%   +5.08%        (p=0.006 n=10+10)
Cond32-48               13.4µs ± 6%   13.1µs ± 5%   -2.75%        (p=0.023 n=10+10)
RWMutexWrite100-48      53.2ns ± 3%   41.2ns ± 3%  -22.57%        (p=0.000 n=10+10)
RWMutexWrite10-48       45.9ns ± 2%   43.9ns ± 2%   -4.38%        (p=0.000 n=10+10)
RWMutexWorkWrite100-48   122ns ± 2%    134ns ± 1%   +9.92%        (p=0.000 n=10+10)
RWMutexWorkWrite10-48    206ns ± 1%    188ns ± 1%   -8.52%         (p=0.000 n=8+10)
Cond32-24               12.1µs ± 3%   12.4µs ± 3%   +1.98%         (p=0.043 n=10+9)
MutexUncontended-24     0.74ns ± 1%   0.75ns ± 1%     ~           (p=0.650 n=10+10)
Mutex-24                 122ns ± 2%    124ns ± 1%   +1.31%        (p=0.007 n=10+10)
MutexSlack-24           96.9ns ± 2%  102.8ns ± 2%   +6.11%        (p=0.000 n=10+10)
MutexWork-24             146ns ± 1%    135ns ± 2%   -7.70%         (p=0.000 n=10+9)
MutexWorkSlack-24        135ns ± 1%    128ns ± 2%   -5.01%         (p=0.000 n=10+9)
MutexNoSpin-24           114ns ± 3%    110ns ± 4%   -3.84%        (p=0.000 n=10+10)
MutexSpin-24             482ns ± 4%    475ns ± 8%     ~           (p=0.286 n=10+10)
RWMutexWrite100-24      43.0ns ± 3%   43.1ns ± 2%     ~           (p=0.956 n=10+10)
RWMutexWrite10-24       43.4ns ± 1%   43.2ns ± 1%     ~            (p=0.085 n=10+9)
RWMutexWorkWrite100-24   130ns ± 3%    131ns ± 3%     ~           (p=0.747 n=10+10)
RWMutexWorkWrite10-24    191ns ± 1%    192ns ± 1%     ~           (p=0.210 n=10+10)
Cond32-12               11.5µs ± 2%   11.7µs ± 2%   +1.98%        (p=0.002 n=10+10)
MutexUncontended-12     1.48ns ± 0%   1.50ns ± 1%   +1.08%        (p=0.004 n=10+10)
Mutex-12                 141ns ± 1%    143ns ± 1%   +1.63%        (p=0.000 n=10+10)
MutexSlack-12            121ns ± 0%    119ns ± 0%   -1.65%          (p=0.001 n=8+9)
MutexWork-12             141ns ± 2%    150ns ± 3%   +6.36%         (p=0.000 n=9+10)
MutexWorkSlack-12        131ns ± 0%    138ns ± 0%   +5.73%         (p=0.000 n=9+10)
MutexNoSpin-12          87.0ns ± 1%   83.7ns ± 1%   -3.80%        (p=0.000 n=10+10)
MutexSpin-12             364ns ± 1%    377ns ± 1%   +3.77%        (p=0.000 n=10+10)
RWMutexWrite100-12      42.8ns ± 1%   43.9ns ± 1%   +2.41%         (p=0.000 n=8+10)
RWMutexWrite10-12       39.8ns ± 4%   39.3ns ± 1%     ~            (p=0.433 n=10+9)
RWMutexWorkWrite100-12   131ns ± 1%    131ns ± 0%     ~            (p=0.591 n=10+9)
RWMutexWorkWrite10-12    173ns ± 1%    174ns ± 0%     ~            (p=0.059 n=10+8)
Cond32-6                10.9µs ± 2%   10.9µs ± 2%     ~           (p=0.739 n=10+10)
MutexUncontended-6      2.97ns ± 0%   2.97ns ± 0%     ~     (all samples are equal)
Mutex-6                  122ns ± 6%    122ns ± 2%     ~           (p=0.668 n=10+10)
MutexSlack-6             149ns ± 3%    142ns ± 3%   -4.63%        (p=0.000 n=10+10)
MutexWork-6              136ns ± 3%    140ns ± 5%     ~           (p=0.077 n=10+10)
MutexWorkSlack-6         152ns ± 0%    138ns ± 2%   -9.21%         (p=0.000 n=6+10)
MutexNoSpin-6            150ns ± 1%    152ns ± 0%   +1.50%         (p=0.000 n=8+10)
MutexSpin-6              726ns ± 0%    730ns ± 1%     ~           (p=0.069 n=10+10)
RWMutexWrite100-6       40.6ns ± 1%   40.9ns ± 1%   +0.91%         (p=0.001 n=8+10)
RWMutexWrite10-6        37.1ns ± 0%   37.0ns ± 1%     ~            (p=0.386 n=9+10)
RWMutexWorkWrite100-6    133ns ± 1%    134ns ± 1%   +1.01%         (p=0.005 n=9+10)
RWMutexWorkWrite10-6     152ns ± 0%    152ns ± 0%     ~     (all samples are equal)
Cond32-2                7.86µs ± 2%   7.95µs ± 2%   +1.10%        (p=0.023 n=10+10)
MutexUncontended-2      8.10ns ± 0%   9.11ns ± 4%  +12.44%         (p=0.000 n=9+10)
Mutex-2                 32.9ns ± 9%   38.4ns ± 6%  +16.58%        (p=0.000 n=10+10)
MutexSlack-2            93.4ns ± 1%   98.5ns ± 2%   +5.39%         (p=0.000 n=10+9)
MutexWork-2             40.8ns ± 3%   43.8ns ± 7%   +7.38%         (p=0.000 n=10+9)
MutexWorkSlack-2        98.6ns ± 5%  108.2ns ± 2%   +9.80%         (p=0.000 n=10+8)
MutexNoSpin-2            399ns ± 1%    398ns ± 2%     ~             (p=0.463 n=8+9)
MutexSpin-2             1.99µs ± 3%   1.97µs ± 1%   -0.81%          (p=0.003 n=9+8)
RWMutexWrite100-2       37.6ns ± 5%   46.0ns ± 4%  +22.17%         (p=0.000 n=10+8)
RWMutexWrite10-2        50.1ns ± 6%   36.8ns ±12%  -26.46%         (p=0.000 n=9+10)
RWMutexWorkWrite100-2    136ns ± 0%    134ns ± 2%   -1.80%          (p=0.001 n=7+9)
RWMutexWorkWrite10-2     140ns ± 1%    138ns ± 1%   -1.50%        (p=0.000 n=10+10)
Cond32                  5.93µs ± 1%   5.91µs ± 0%     ~            (p=0.411 n=9+10)
MutexUncontended        15.9ns ± 0%   15.8ns ± 0%   -0.63%          (p=0.000 n=8+8)
Mutex                   15.9ns ± 0%   15.8ns ± 0%   -0.44%        (p=0.003 n=10+10)
MutexSlack              26.9ns ± 3%   26.7ns ± 2%     ~           (p=0.084 n=10+10)
MutexWork               47.8ns ± 0%   47.9ns ± 0%   +0.21%          (p=0.014 n=9+8)
MutexWorkSlack          54.9ns ± 3%   54.5ns ± 3%     ~           (p=0.254 n=10+10)
MutexNoSpin              786ns ± 2%    765ns ± 1%   -2.66%        (p=0.000 n=10+10)
MutexSpin               3.87µs ± 1%   3.83µs ± 0%   -0.85%          (p=0.005 n=9+8)
RWMutexWrite100         21.2ns ± 2%   21.0ns ± 1%   -0.88%         (p=0.018 n=10+9)
RWMutexWrite10          22.6ns ± 1%   22.6ns ± 0%     ~             (p=0.471 n=9+9)
RWMutexWorkWrite100      132ns ± 0%    132ns ± 0%     ~     (all samples are equal)
RWMutexWorkWrite10       124ns ± 0%    123ns ± 0%     ~           (p=0.656 n=10+10)

Change-Id: I66412a3a0980df1233ad7a5a0cd9723b4274528b
Reviewed-on: https://go-review.googlesource.com/34310
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2017-02-17 17:24:59 +00:00
Wander Lairson Costa
79f6a5c7bd syscall: only call setgroups if we need to
If the caller set ups a Credential in os/exec.Command,
os/exec.Command.Start will end up calling setgroups(2), even if no
supplementary groups were given.

Only root can call setgroups(2) on BSD kernels, which causes Start to
fail for non-root users when they try to set uid and gid for the new
process.

We fix by introducing a new field to syscall.Credential named
NoSetGroups, and setgroups(2) is only called if it is false.
We make this field with inverted logic to preserve backward
compatibility.

RELNOTES=yes

Change-Id: I3cff1f21c117a1430834f640ef21fd4e87e06804
Reviewed-on: https://go-review.googlesource.com/36697
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-17 14:36:27 +00:00
Keith Randall
708ba22a0c cmd/compile: move constant divide strength reduction to SSA rules
Currently the conversion from constant divides to multiplies is mostly
done during the walk pass.  This is suboptimal because SSA can
determine that the value being divided by is constant more often
(e.g. after inlining).

Change-Id: If1a9b993edd71be37396b9167f77da271966f85f
Reviewed-on: https://go-review.googlesource.com/37015
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2017-02-17 06:16:44 +00:00
Matthew Dempsky
794f1ebff7 cmd/compile: simplify needwritebarrier
Currently, whether we need a write barrier is simply a property of the
pointer slot being written to.

The only optimization we currently apply using the value being written
is that pointers to stack variables can omit write barriers because
they're only written to stack slots... but we already omit write
barriers for all writes to the stack anyway.

Passes toolstash -cmp.

Change-Id: I7f16b71ff473899ed96706232d371d5b2b7ae789
Reviewed-on: https://go-review.googlesource.com/37109
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-16 22:42:36 +00:00
Shenghou Ma
211102c85f math: fix typos in Bessel function docs
While we're at it, also document Yn(0, 0) = -Inf for completeness.

Fixes #18823.

Change-Id: Ib6db68f76d29cc2373c12ebdf3fab129cac8c167
Reviewed-on: https://go-review.googlesource.com/35970
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-16 22:41:34 +00:00
Robert Griesemer
661e2179e5 math/bits: added package for bit-level counting and manipulation
Initial platform-independent implementation.

For #18616.

Change-Id: I4585c55b963101af9059c06c1b8a866cb384754c
Reviewed-on: https://go-review.googlesource.com/36315
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2017-02-16 21:54:59 +00:00
Robert Griesemer
1693e7b6f2 cmd/compile/internal/syntax: better errors and recovery for invalid character literals
Fixes #15611.

Change-Id: I352b145026466cafef8cf87addafbd30716bda24
Reviewed-on: https://go-review.googlesource.com/37138
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-02-16 21:46:43 +00:00
Russ Cox
990124da2a runtime: use balanced tree for addr lookup in semaphore implementation
CL 36792 fixed #17953, a linear scan caused by n goroutines piling into
two different locks that hashed to the same bucket in the semaphore table.
In that CL, n goroutines contending for 2 unfortunately chosen locks
went from O(n²) to O(n).

This CL fixes a different linear scan, when n goroutines are contending for
n/2 different locks that all hash to the same bucket in the semaphore table.
In this CL, n goroutines contending for n/2 unfortunately chosen locks
goes from O(n²) to O(n log n). This case is much less likely, but any linear
scan eventually hurts, so we might as well fix it while the problem is fresh
in our minds.

The new test in this CL checks for both linear scans.

The effect of this CL on the sync benchmarks is negligible
(but it fixes the new test).

name                      old time/op    new time/op    delta
Cond1-48                     576ns ±10%     575ns ±13%     ~     (p=0.679 n=71+71)
Cond2-48                    1.59µs ± 8%    1.61µs ± 9%     ~     (p=0.107 n=73+69)
Cond4-48                    4.56µs ± 7%    4.55µs ± 7%     ~     (p=0.670 n=74+72)
Cond8-48                    9.87µs ± 9%    9.90µs ± 7%     ~     (p=0.507 n=69+73)
Cond16-48                   20.4µs ± 7%    20.4µs ±10%     ~     (p=0.588 n=69+71)
Cond32-48                   45.4µs ±10%    45.4µs ±14%     ~     (p=0.944 n=73+73)
UncontendedSemaphore-48     19.7ns ±12%    19.7ns ± 8%     ~     (p=0.589 n=65+63)
ContendedSemaphore-48       55.4ns ±26%    54.9ns ±32%     ~     (p=0.441 n=75+75)
MutexUncontended-48         0.63ns ± 0%    0.63ns ± 0%     ~     (all equal)
Mutex-48                     210ns ± 6%     213ns ±10%   +1.30%  (p=0.035 n=70+74)
MutexSlack-48                210ns ± 7%     211ns ± 9%     ~     (p=0.184 n=71+72)
MutexWork-48                 299ns ± 5%     300ns ± 5%     ~     (p=0.678 n=73+75)
MutexWorkSlack-48            302ns ± 6%     300ns ± 5%     ~     (p=0.149 n=74+72)
MutexNoSpin-48               135ns ± 6%     135ns ±10%     ~     (p=0.788 n=67+75)
MutexSpin-48                 693ns ± 5%     689ns ± 6%     ~     (p=0.092 n=65+74)
Once-48                     0.22ns ±25%    0.22ns ±24%     ~     (p=0.882 n=74+73)
Pool-48                     5.88ns ±36%    5.79ns ±24%     ~     (p=0.655 n=69+69)
PoolOverflow-48             4.79µs ±18%    4.87µs ±20%     ~     (p=0.233 n=75+75)
SemaUncontended-48          0.80ns ± 1%    0.82ns ± 8%   +2.46%  (p=0.000 n=60+74)
SemaSyntNonblock-48          103ns ± 4%     102ns ± 5%   -1.11%  (p=0.003 n=75+75)
SemaSyntBlock-48             104ns ± 4%     104ns ± 5%     ~     (p=0.231 n=71+75)
SemaWorkNonblock-48          128ns ± 4%     129ns ± 6%   +1.51%  (p=0.000 n=63+75)
SemaWorkBlock-48             129ns ± 8%     130ns ± 7%     ~     (p=0.072 n=75+74)
RWMutexUncontended-48       2.35ns ± 1%    2.35ns ± 0%     ~     (p=0.144 n=70+55)
RWMutexWrite100-48           139ns ±18%     141ns ±21%     ~     (p=0.071 n=75+73)
RWMutexWrite10-48            145ns ± 9%     145ns ± 8%     ~     (p=0.553 n=75+75)
RWMutexWorkWrite100-48       297ns ±13%     297ns ±15%     ~     (p=0.519 n=75+74)
RWMutexWorkWrite10-48        588ns ± 7%     585ns ± 5%     ~     (p=0.173 n=73+70)
WaitGroupUncontended-48     0.87ns ± 0%    0.87ns ± 0%     ~     (all equal)
WaitGroupAddDone-48         63.2ns ± 4%    62.7ns ± 4%   -0.82%  (p=0.027 n=72+75)
WaitGroupAddDoneWork-48      109ns ± 5%     109ns ± 4%     ~     (p=0.233 n=75+75)
WaitGroupWait-48            0.17ns ± 0%    0.16ns ±16%   -8.55%  (p=0.000 n=56+75)
WaitGroupWaitWork-48        1.78ns ± 1%    2.08ns ± 5%  +16.92%  (p=0.000 n=74+70)
WaitGroupActuallyWait-48    52.0ns ± 3%    50.6ns ± 5%   -2.70%  (p=0.000 n=71+69)

https://perf.golang.org/search?q=upload:20170215.1

Change-Id: Ia29a8bd006c089e401ec4297c3038cca656bcd0a
Reviewed-on: https://go-review.googlesource.com/37103
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-16 17:52:15 +00:00
Matthew Dempsky
fc456c7f7b cmd/compile/internal/gc: drop unused src.XPos params in SSA builder
Passes toolstash -cmp.

Change-Id: I037278404ebf762482557e2b6867cbc595074a83
Reviewed-on: https://go-review.googlesource.com/37023
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2017-02-16 17:34:39 +00:00