There is currently no way for os.FileMode.IsRegular to report false
without being one of the following types:
	ModeDir | ModeSymlink | ModeNamedPipe | ModeSocket | ModeDevice

This makes it difficult for custom implementations of os.FileInfo to return
a Mode that is explicitly not regular without resorting to setting one
of the types listed above. However, every one of the aforementioned types
are ill-suited as a general-purpose "not regular" file type.

Thus, add a ModeIrregular to serve exactly for that purpose.
The ModeIrregular type carries no information other than the fact that the
file is not regular.

Updates #22903
Fixes #23878

Change-Id: I4f34d88f960bcb014816d8e7b5de8b1035077948
Reviewed-on: https://go-review.googlesource.com/94856Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Before this change, the smallest result Ldexp can handle was
ldexp(2, -1075), which is SmallestNonzeroFloat64.
There are some numbers below it should also be rounded to
SmallestNonzeroFloat64. The change fixes this.

Fixes #23407

Change-Id: I76f4cb005a6e9ccdd95b5e5c734079fd5d29e4aa
Reviewed-on: https://go-review.googlesource.com/87338
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Incorporate https://code-review.googlesource.com/#/c/re2/+/3050/ from
the re2 repository. Description of that change:

    Preserve the original behaviour of \s.

    Prior to Perl 5.18, \s did not match vertical tab. Bake that into
    make_perl_groups.pl as an override so that perl_groups.cc retains
    its current definitions when rebuilt with newer versions of Perl.

This fixes make_perl_groups.pl to generate an unchanged perl_groups.go
with perl versions 5.18 and later.

Fixes #22057

Change-Id: I9a56e9660092ed6c1ff1045b4a3847de355441a7
Reviewed-on: https://go-review.googlesource.com/103517
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Pulling these operations out separately so it's easier to add
instrumentation calls.

Passes toolstash-check.

Updates #19054.

Change-Id: If6a537124a87bac2eceff1d66d9df5ebb3bf07be
Reviewed-on: https://go-review.googlesource.com/102816Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I99407e27e340689009af798989b33cef7cb92070
Reviewed-on: https://go-review.googlesource.com/103376
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This change modifies the codegen test harness driver so that it no
longer modifies the environment GOOS/GOARCH, since that seems to cause
flakiness in other concurrently-running tests.

The change also enables the codegen tests in run.go.

Fixes #24538

Change-Id: I997ac1eb38eb92054efff67fe5c4d3cccc86412b
Reviewed-on: https://go-review.googlesource.com/103455
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This resolves a long-standing regalloc TODO:
If you must evict a register, choose to evict a register
containing a rematerializable value, since that value
won't need to be spilled.

Provides very minor performance and size improvements.

name                     old time/op    new time/op    delta
BinaryTree17-8              2.20s ± 3%     2.18s ± 2%  -0.77%  (p=0.000 n=45+49)
Fannkuch11-8                2.14s ± 2%     2.15s ± 2%  +0.73%  (p=0.000 n=43+44)
FmtFprintfEmpty-8          30.6ns ± 4%    30.2ns ± 3%  -1.14%  (p=0.000 n=50+48)
FmtFprintfString-8         54.5ns ± 6%    53.6ns ± 5%  -1.64%  (p=0.001 n=50+48)
FmtFprintfInt-8            58.0ns ± 7%    57.6ns ± 4%    ~     (p=0.220 n=50+50)
FmtFprintfIntInt-8         85.3ns ± 2%    84.8ns ± 3%  -0.62%  (p=0.001 n=44+47)
FmtFprintfPrefixedInt-8    93.9ns ± 6%    93.6ns ± 5%    ~     (p=0.706 n=50+48)
FmtFprintfFloat-8           178ns ± 4%     177ns ± 4%    ~     (p=0.107 n=49+50)
FmtManyArgs-8               376ns ± 4%     374ns ± 3%  -0.58%  (p=0.013 n=45+50)
GobDecode-8                4.77ms ± 2%    4.76ms ± 3%    ~     (p=0.059 n=47+46)
GobEncode-8                4.04ms ± 2%    3.99ms ± 3%  -1.13%  (p=0.000 n=49+49)
Gzip-8                      177ms ± 2%     180ms ± 3%  +1.43%  (p=0.000 n=48+48)
Gunzip-8                   28.5ms ± 6%    28.3ms ± 5%    ~     (p=0.104 n=50+49)
HTTPClientServer-8         72.1µs ± 1%    72.0µs ± 1%  -0.15%  (p=0.042 n=48+42)
JSONEncode-8               9.81ms ± 5%   10.03ms ± 6%  +2.29%  (p=0.000 n=50+49)
JSONDecode-8               39.2ms ± 3%    39.3ms ± 2%    ~     (p=0.095 n=49+49)
Mandelbrot200-8            3.48ms ± 2%    3.46ms ± 2%  -0.80%  (p=0.000 n=47+48)
GoParse-8                  2.54ms ± 3%    2.51ms ± 3%  -1.35%  (p=0.000 n=49+49)
RegexpMatchEasy0_32-8      66.0ns ± 7%    65.7ns ± 8%    ~     (p=0.331 n=50+50)
RegexpMatchEasy0_1K-8       155ns ± 4%     154ns ± 4%    ~     (p=0.986 n=49+50)
RegexpMatchEasy1_32-8      62.6ns ± 8%    62.2ns ± 5%    ~     (p=0.395 n=50+49)
RegexpMatchEasy1_1K-8       260ns ± 5%     255ns ± 3%  -1.92%  (p=0.000 n=49+49)
RegexpMatchMedium_32-8     92.9ns ± 2%    91.8ns ± 2%  -1.25%  (p=0.000 n=46+48)
RegexpMatchMedium_1K-8     27.7µs ± 3%    27.0µs ± 2%  -2.59%  (p=0.000 n=49+49)
RegexpMatchHard_32-8       1.23µs ± 4%    1.21µs ± 2%  -2.16%  (p=0.000 n=49+44)
RegexpMatchHard_1K-8       36.4µs ± 2%    35.7µs ± 2%  -1.87%  (p=0.000 n=48+49)
Revcomp-8                   274ms ± 2%     276ms ± 3%  +0.70%  (p=0.034 n=45+48)
Template-8                 45.1ms ± 8%    45.1ms ± 8%    ~     (p=0.643 n=50+50)
TimeParse-8                 223ns ± 2%     223ns ± 2%    ~     (p=0.401 n=47+47)
TimeFormat-8                245ns ± 2%     246ns ± 3%    ~     (p=0.758 n=49+50)
[Geo mean]                 36.5µs         36.3µs       -0.54%


name        old object-bytes  new object-bytes  delta
Template          480kB ± 0%        480kB ± 0%    ~     (all equal)
Unicode           214kB ± 0%        214kB ± 0%    ~     (all equal)
GoTypes          1.54MB ± 0%       1.54MB ± 0%  -0.03%  (p=0.008 n=5+5)
Compiler         5.75MB ± 0%       5.75MB ± 0%    ~     (all equal)
SSA              14.6MB ± 0%       14.6MB ± 0%  -0.01%  (p=0.008 n=5+5)
Flate             300kB ± 0%        300kB ± 0%  -0.01%  (p=0.008 n=5+5)
GoParser          366kB ± 0%        366kB ± 0%    ~     (all equal)
Reflect          1.20MB ± 0%       1.20MB ± 0%    ~     (all equal)
Tar               413kB ± 0%        413kB ± 0%    ~     (all equal)
XML               529kB ± 0%        528kB ± 0%  -0.13%  (p=0.008 n=5+5)
[Geo mean]        909kB             909kB       -0.02%


Change-Id: I46d37a55197683a98913f35801dc2b0d609653c8
Reviewed-on: https://go-review.googlesource.com/103240
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

The existing behaviour of go generate is to pass GOPACKAGE=p
to all package files, including XTest files. This however is
incorrect as the package name for the XTest files is p_test.

Fixes #24594

Change-Id: I96b6e5777ec511cdcf1a6267a43f4d8c544c4af3
Reviewed-on: https://go-review.googlesource.com/103415
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Mostly same as golang.org/cl/102156, except the parts that
deal with different data types.

Change-Id: I061b858b73898725e3bf175ed022c2e3e55fc485
Reviewed-on: https://go-review.googlesource.com/103158Reviewed-by: Andrew Bonventre <andybons@golang.org>

Using go test -c makes you responsible for managing and merging the
coverage profile yourself.

Fixes #24588

Change-Id: I2037a91ceb904f9f35d76c7b5e5fae6bcbed4e46
Reviewed-on: https://go-review.googlesource.com/103395
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: If56bd72917a9cbf5920ae8b5a36dc67f10959b94
Reviewed-on: https://go-review.googlesource.com/103175
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

Decode AT_PAGESZ to determine physPageSize on dragonfly.

Change-Id: I7236d7cbe43433f16dffddad19c1655bc0c7f31d
Reviewed-on: https://go-review.googlesource.com/103257
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The escape_because.go test file (which tests the "because" escape
explainations printed by `-m -m`) cointains a machine-generated list
of all the escape reasons seen in the escape tests.

The list appears to be outdated; moreove a new escape reason was added
in CL 102895. This change re-generates the list.

Change-Id: Idc721c6bbfe9516895b5cf1e6d09b77deda5a3dd
Reviewed-on: https://go-review.googlesource.com/103375Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #23164

Change-Id: I6e8c6443f3ef91df71e117cce1cfa1faba647dd7
Reviewed-on: https://go-review.googlesource.com/87337Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

-race sets a hard cap of 8,192, which is easily hit while testing.

Fixes #23611

Change-Id: I0f720ec39c82c2194a485d437d6373f4bdc8a9c1
Reviewed-on: https://go-review.googlesource.com/103160Reviewed-by: Rob Pike <r@golang.org>

Change-Id: I7c0716711a2cadd347fdf242c792b109539f7355
Reviewed-on: https://go-review.googlesource.com/103163Reviewed-by: Andrew Bonventre <andybons@golang.org>

Change-Id: Idf88d289bac9603d852a9d19eb4b764f8589f8d9
Reviewed-on: https://go-review.googlesource.com/103159Reviewed-by: Andrew Bonventre <andybons@golang.org>

Fixes #23264

Change-Id: Ib6c343dc8e32949c6de72cb628cace2e8fabc302
Reviewed-on: https://go-review.googlesource.com/103236
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

In general use of these magic methods must be documented so that
users understand what will happen.

Fixes #23289

Change-Id: Ic46915eee1d3b7e57d8d1886834ddfb2e8e66e62
Reviewed-on: https://go-review.googlesource.com/103238Reviewed-by: Rob Pike <r@golang.org>

Change-Id: I8f12b188d2e13555e1d7634b9cc0319fc737cb1d
Reviewed-on: https://go-review.googlesource.com/103216Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Ibba5d4fd8124db9b1e4e50b8f37366f8dd23f47e
Reviewed-on: https://go-review.googlesource.com/103217Reviewed-by: Ian Lance Taylor <iant@golang.org>

A very small number of old browsers consider content as HTML
even when it is explicitly stated in the Content-Type header
that it is not. If content served is based on user-supplied
input, then an XSS is possible. Introduce three mitigations:

+ Don't reflect user input in error strings
+ Set a Content-Disposition header when requesting a resource
  that should never be displayed in a browser window
+ Set X-Content-Type-Options: nosniff on all responses

Change-Id: I81c9d6736e0439ebd1db99cd7fb701cc56d24805
Reviewed-on: https://go-review.googlesource.com/102318
Run-TryBot: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #24225

Change-Id: I876ac1b9d3615283f7b88cfa0b965ef81a57f056
Reviewed-on: https://go-review.googlesource.com/102955Reviewed-by: Rob Pike <r@golang.org>

When snapshotting the execution time stats of a goroutine
we take into account the intermediate values kepts in the GDesc's
gdesc field. At the end of goroutine analysis, we go through all
goroutines and replace the GExecutionStat with the new snapshot.
Here the mistake was that we replaced the GExecutionStat with
the value that reflects the intermediate values, but did clear
the intermediate values. So, when the following finalizeActiveSpans
runs, it trieds to add the intermediate values again (double-counting)
when taking a snapshot.

Fix the issue by using the finalized GExecutionStat instead of
recomputing the snapshot. While we are here, refactor the finalization
logic so it can be used when processing GoEnd, GoStop events.

Change-Id: Ibdb342214c29b65d4ea37e52b1f8b83f1fb20143
Reviewed-on: https://go-review.googlesource.com/103157Reviewed-by: Peter Weinberger <pjw@google.com>

Fixes #24132


name                     old time/op    new time/op    delta
BinaryTree17-8              2.18s ± 2%     2.15s ± 2%  -1.28%  (p=0.000 n=25+26)
Fannkuch11-8                2.16s ± 3%     2.13s ± 3%  -1.54%  (p=0.000 n=27+30)
FmtFprintfEmpty-8          29.9ns ± 3%    29.6ns ± 3%  -1.08%  (p=0.001 n=29+26)
FmtFprintfString-8         53.6ns ± 2%    54.0ns ± 4%    ~     (p=0.193 n=28+29)
FmtFprintfInt-8            56.8ns ± 3%    57.0ns ± 3%    ~     (p=0.330 n=29+29)
FmtFprintfIntInt-8         85.3ns ± 2%    85.8ns ± 3%  +0.56%  (p=0.042 n=30+29)
FmtFprintfPrefixedInt-8    94.1ns ± 5%    99.0ns ± 8%  +5.20%  (p=0.000 n=27+30)
FmtFprintfFloat-8           183ns ± 4%     182ns ± 3%    ~     (p=0.619 n=30+26)
FmtManyArgs-8               369ns ± 2%     369ns ± 2%    ~     (p=0.748 n=27+29)
GobDecode-8                4.78ms ± 2%    4.75ms ± 1%    ~     (p=0.051 n=28+27)
GobEncode-8                4.06ms ± 3%    4.07ms ± 3%    ~     (p=0.781 n=29+30)
Gzip-8                      178ms ± 2%     177ms ± 2%    ~     (p=0.171 n=29+30)
Gunzip-8                   28.2ms ± 7%    28.0ms ± 4%    ~     (p=0.155 n=30+30)
HTTPClientServer-8         71.5µs ± 3%    71.3µs ± 1%    ~     (p=0.913 n=25+27)
JSONEncode-8               9.71ms ± 5%    9.86ms ± 4%  +1.55%  (p=0.015 n=28+30)
JSONDecode-8               38.8ms ± 2%    39.3ms ± 2%  +1.41%  (p=0.000 n=28+29)
Mandelbrot200-8            3.47ms ± 6%    3.44ms ± 3%    ~     (p=0.183 n=28+28)
GoParse-8                  2.55ms ± 2%    2.54ms ± 3%  -0.58%  (p=0.003 n=27+29)
RegexpMatchEasy0_32-8      66.0ns ± 5%    65.3ns ± 4%    ~     (p=0.124 n=30+30)
RegexpMatchEasy0_1K-8       152ns ± 2%     152ns ± 3%    ~     (p=0.881 n=30+30)
RegexpMatchEasy1_32-8      62.9ns ± 9%    62.7ns ± 7%    ~     (p=0.717 n=30+30)
RegexpMatchEasy1_1K-8       263ns ± 3%     263ns ± 4%    ~     (p=0.909 n=30+29)
RegexpMatchMedium_32-8     93.4ns ± 3%    89.3ns ± 2%  -4.32%  (p=0.000 n=29+29)
RegexpMatchMedium_1K-8     27.5µs ± 3%    27.1µs ± 2%  -1.46%  (p=0.000 n=30+27)
RegexpMatchHard_32-8       1.33µs ± 3%    1.31µs ± 3%  -1.50%  (p=0.000 n=27+28)
RegexpMatchHard_1K-8       39.4µs ± 2%    39.1µs ± 2%  -0.54%  (p=0.027 n=28+28)
Revcomp-8                   274ms ± 4%     276ms ± 2%  +0.67%  (p=0.048 n=29+28)
Template-8                 45.1ms ± 5%    44.6ms ± 7%  -1.22%  (p=0.029 n=30+29)
TimeParse-8                 227ns ± 3%     224ns ± 3%  -1.25%  (p=0.000 n=28+27)
TimeFormat-8                248ns ± 3%     245ns ± 3%  -1.33%  (p=0.002 n=30+29)
[Geo mean]                 36.6µs         36.5µs       -0.32%


Change-Id: I24083f0013506b77e2d9da99c40ae2f67803285e
Reviewed-on: https://go-review.googlesource.com/101076
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

The additions were machine-generated.

The change for x * 7 avoids a reg-reg move,
reducing the number of instructions from 3 to 2.

Change-Id: Ib002e39f29ca5e46cfdb8daaf87ddc7ba50a17e5
Reviewed-on: https://go-review.googlesource.com/102395
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

If the character after $ cannot be detected as a valid
variable declaration, do not gobble the $.

Fixes #24345

Change-Id: Iec47be1f2e4f8147b8ceb64c30778eae8045b58f
Reviewed-on: https://go-review.googlesource.com/103055
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This change reduces the time to run this test on my machine from

real	0m2.491s
user	0m3.020s
sys	0m0.331s

to

real	0m0.237s
user	0m0.180s
sys	0m0.173s

This will make it reasonable to add more constants to the test.
I am also hopeful that it might help a bit with intermittent
cmd/compile/internal/gc test timeouts on the build dashboard
on the slower builders.

The time savings are entirely in compilation time,
by avoiding generating one giant func main.
Instead, generate tables of tests to be run,
which are translated into static data,
and then loop over those tests.

While we're here, do some minor cleanup:

* Remove the _ssa suffix on function names,
  as that was only needed during ssa bootstrapping.
* Clean up error handling during test generation.
* Make functions single-line, to reduce future diff sizes.
  Diffing giant files is slow.

Change-Id: Ic5fccdb71679169bea756c7d33c07d05e4801860
Reviewed-on: https://go-review.googlesource.com/102956
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

This change makes `-m -m` print a better explanation for the case
where a slice is marked as escaping and heap-allocated because it
has a non-constant len/cap.

Fixes #24578

Change-Id: I0ebafb77c758a99857d72b365817bdba7b446cc0
Reviewed-on: https://go-review.googlesource.com/102895Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>

Use internal/cpu instead.

Change-Id: I8670440389cbd88951fee61e352c4a10ac7eee6e
Reviewed-on: https://go-review.googlesource.com/102737
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #23937

Change-Id: Ie63d91355d1a724d0012d99d457d939deeeb8d3e
Reviewed-on: https://go-review.googlesource.com/102818
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Bonventre <andybons@golang.org>

When parsing an ECDSA certificate, improve the error message upon
failing to parse the curve as a named curve, rather than returning
the original ASN1 error.

Fixes #21502

Change-Id: I7ae7b3ea7a9dcbd78a9607f46f5883d3193b8367
Reviewed-on: https://go-review.googlesource.com/57050Reviewed-by: Filippo Valsorda <filippo@golang.org>

Fixes #24526

Change-Id: I0e38322fca12f9c88db836776920b9dfb66ff844
Reviewed-on: https://go-review.googlesource.com/102423Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Rob Pike <r@golang.org>

Don't compile the runtime packages with coverage when using the race
detector. The user can, perhaps accidentally, request coverage for the
runtime by using -coverpkg=all. If using the race detector, the
runtime package coverage will call into the race detector before it
has been initialized. This will cause the program to crash
mysteriously on startup.

Fixes #23882

Change-Id: I9a63867a9138797d8b8afb0856ae21079accdb27
Reviewed-on: https://go-review.googlesource.com/94898
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Bonventre <andybons@golang.org>

parsePrivateKey can't return useful error messages because it does trial
decoding of multiple formats.  Try ParseCertificate first in case it
offers a useful error message.

Fixes #23591

Change-Id: I380490a5850bee593a7d2f584a27b2a14153d768
Reviewed-on: https://go-review.googlesource.com/90435
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>

Fixes #24540

Change-Id: I65e9f2f99403e22d25ea64cc26701bf62a31d070
Reviewed-on: https://go-review.googlesource.com/102699
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #24389
Fixes #24396

Change-Id: I37399528700e2a39d9523d7c41bdc929618eb095
Reviewed-on: https://go-review.googlesource.com/102619Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This CL implements Exp and Exp2 with arm64 assembly. By inlining Ldexp and
using fused instructions(fmadd, fmsub, fnmsub), this CL helps to improve
the performance of functions Exp, Exp2, Sinh, Cosh and Tanh.

Benchmarks:
name                   old time/op  new time/op  delta
Cosh-8                  138ns ± 0%    96ns ± 0%  -30.72%  (p=0.008 n=5+5)
Exp-8                   105ns ± 0%    58ns ± 0%  -45.24%  (p=0.000 n=5+4)
Exp2-8                  100ns ± 0%    57ns ± 0%  -43.21%  (p=0.008 n=5+5)
Sinh-8                  139ns ± 0%   102ns ± 0%  -26.62%  (p=0.008 n=5+5)
Tanh-8                  134ns ± 0%   100ns ± 0%  -25.67%  (p=0.008 n=5+5)

Change-Id: I7483a3333062a1d3525cedf3de56db78d79031c6
Reviewed-on: https://go-review.googlesource.com/86615
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Change-Id: Ib67a61d5b37af210ff15d60d72bd5238b9c2d0ca
Reviewed-on: https://go-review.googlesource.com/94815
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1. STPW stores the lower 32-bit words of a pair of registers to memory.
2. LDPW loads two 32-bit words from memory, zero extends them to 64-bit,
and then copies to a pair of registers.
3. LDPSW does the same as LDPW, except a sign extension.

This CL implements those 3 instructions and adds test cases.

Change-Id: Ied9834d8240240d23ce00e086b4ea456e1611f1a
Reviewed-on: https://go-review.googlesource.com/99956
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>