This CL implements the following optimizations for ARM:
- use shifted ops (e.g. ADD R1<<2, R2) and indexed load/stores
- break up shift ops. Shifts used to be one SSA op that generates
  multiple instructions. We break them up to multiple ops, which
  allows constant folding and CSE for comparisons. Conditional moves
  are introduced for this.
- simplify zero/sign-extension ops.

Updates #15365.

Change-Id: I55e262a776a7ef2a1505d75e04d1208913c35d39
Reviewed-on: https://go-review.googlesource.com/24512
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Basically just copied all the amd64 files, removed all the *Q ops,
and rebuilt.

Compiles fib successfully.

Still need to do:
 - all the 64->32 bit op translations.
 - audit for instructions that aren't available on 386.
 - GO386=387?

Update #16358

Change-Id: Ib8c684586416a554a527a5eefa0cff71424e36f5
Reviewed-on: https://go-review.googlesource.com/24912Reviewed-by: Cherry Zhang <cherryyz@google.com>

Semi-regular merge of tip into dev.ssa.

Change-Id: I855817c4746237792a2dab6eaf471087a3646be4

Document that the http.Server is now stricter about rejecting
requests with invalid HTTP versions, and also that it rejects plaintext
HTTP/2 requests, except for `PRI * HTTP/2.0` upgrade requests.
The relevant CL is https://golang.org/cl/24505.

Updates #15810.

Change-Id: Ibbace23e001b5e2eee053bd341de50f9b6d3fde8
Reviewed-on: https://go-review.googlesource.com/24731Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

New Gophers sometimes misconstrue the advice in the "Generality" section
as "export interfaces instead of implementations" and add needless
interfaces to their code as a result.  Down the road, they end up
needing to add methods and either break existing callers or have to
resort to unpleasant hacks (e.g. using "magic method" type-switches).

Weaken the first paragraph of this section to only advise leaving types
unexported when they will never need additional methods.

Change-Id: I32a1ae44012b5896faf167c02e192398a4dfc0b8
Reviewed-on: https://go-review.googlesource.com/24892Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

Fixes #12272

Change-Id: I0306ce0ef4a87df2158df3b7d4d8d93a1cb6dabc
Reviewed-on: https://go-review.googlesource.com/24864Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

The cgocallback function picked up a ctxt parameter in CL 22508.
That CL updated the assembler implementation, but there are a few
mentions in Go code that were not updated. This CL fixes that.

Fixes #16326

Change-Id: I5f68e23565c6a0b11057aff476d13990bff54a66
Reviewed-on: https://go-review.googlesource.com/24848
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

The reflect package was returning a non-empty PkgPath for an unnamed
type with methods, such as a type whose methods have a pointer
receiver.

Fixes #16328.

Change-Id: I733e93981ebb5c5c108ef9b03bf5494930b93cf3
Reviewed-on: https://go-review.googlesource.com/24862Reviewed-by: David Crawshaw <crawshaw@golang.org>

This is a copy of the "FANOUT" benchmark recently added to RE2 with the
following comment:

    // This has quite a high degree of fanout.
    // NFA execution will be particularly slow.

Most of the benchmarks on the regexp package have very little fanout and
are designed for comparing the regexp package's NFA with backtracking
engines found in other regular expression libraries. This benchmark
exercises the performance of the NFA on expressions with high fanout.Reviewed-on: https://go-review.googlesource.com/24846Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
"

This reverts commit fc803874.

Reason for revert: Breaks the -race build because the benchmark takes too long to run.

Change-Id: I6ed4b466f74a4108d8bcd5b019b9abe971eb483e
Reviewed-on: https://go-review.googlesource.com/24861
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>

This is a copy of the "FANOUT" benchmark recently added to RE2 with the
following comment:

    // This has quite a high degree of fanout.
    // NFA execution will be particularly slow.

Most of the benchmarks on the regexp package have very little fanout and
are designed for comparing the regexp package's NFA with backtracking
engines found in other regular expression libraries. This benchmark
exercises the performance of the NFA on expressions with high fanout.

Change-Id: Ie9c8e3bbeffeb1fe9fb90474ddd19e53f2f57a52
Reviewed-on: https://go-review.googlesource.com/24846Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

PrintDefaults already calls os.Exit(2).

Change-Id: I0d783a6476f42b6157853cdb34ba69618e3f3fcb
Reviewed-on: https://go-review.googlesource.com/24844Reviewed-by: Andrew Gerrand <adg@golang.org>

A follow-on to https://golang.org/cl/24852 that mentions the
documentation clarifications.

Updates #16308.

Change-Id: Ic2a6e1d4938d74352f93a6649021fb610efbfcd0
Reviewed-on: https://go-review.googlesource.com/24857
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

There are no synchronization points protecting the readVal and readPos
variables. This leads to a race when Read is called concurrently.
Fix this by adding methods to lockedSource, which is the case where
a race matters.

Fixes #16308.

Change-Id: Ic028909955700906b2d71e5c37c02da21b0f4ad9
Reviewed-on: https://go-review.googlesource.com/24852Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Updates #16230

Change-Id: Ie38f85419c41c00108f8843960280428a39789b5
Reviewed-on: https://go-review.googlesource.com/24850
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #16303.

Change-Id: I2832477ce0117a66da53ca1f198ebb6121953d56
Reviewed-on: https://go-review.googlesource.com/24833
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #16299.

Change-Id: I76f541c7f11edb625df566f2f1035147b8bcd9dd
Reviewed-on: https://go-review.googlesource.com/24830
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

For better or for worse, it's IsExist, not IsExists.

Change-Id: I4503f961486edd459c0c81cf3f32047dff7703a4
Reviewed-on: https://go-review.googlesource.com/24819
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

In the beta version of the macOS Sierra (10.12) release, the
gettimeofday system call changed on x86. Previously it always returned
the time in the AX/DX registers. Now, if AX is returned as 0, it means
that the system call has stored the values into the memory pointed to by
the first argument, just as the libc gettimeofday function does. The
libc function handles both cases, and we need to do so as well.

Fixes #16272.

Change-Id: Ibe5ad50a2c5b125e92b5a4e787db4b5179f6b723
Reviewed-on: https://go-review.googlesource.com/24812Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The shrinkstack code locks all the channels a goroutine is waiting for,
but didn't handle the case of the same channel appearing in the list
multiple times. This led to a deadlock. The channels are sorted so it's
easy to avoid locking the same channel twice.

Fixes #16286.

Change-Id: Ie514805d0532f61c942e85af5b7b8ac405e2ff65
Reviewed-on: https://go-review.googlesource.com/24815
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Fixes #16273

Change-Id: I443e1f254fd683c4ff61beadae89c1c45ff5d972
Reviewed-on: https://go-review.googlesource.com/24744Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Quentin Smith <quentin@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The test was checking for 1 of 2 possible error values. But based on
goroutine scheduling and the randomness of select statement receive
cases, it was possible for a 3rd type of error to be returned.

This modifies the code (not the test) to make that third type of error
actually the second type of error, which is a nicer error message.

The test is no longer flaky. The flake was very reproducible with a
5ms sleep before the select at the end of Transport.getConn.

Thanks to Github user @jaredborner for debugging.

Fixes #16049

Change-Id: I0d2a036c9555a8d2618b07bab01f28558d2b0b2c
Reviewed-on: https://go-review.googlesource.com/24748Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I0c76e8deae49c1149647de421503c5175028b948
Reviewed-on: https://go-review.googlesource.com/24781
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Document explicitly which functions Clean the result rather than
documenting it in the package comment.

Updates #10122.
Fixes #16111.

Change-Id: Ia589c7ee3936c9a6a758725ac7f143054d53e41e
Reviewed-on: https://go-review.googlesource.com/24747
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This new comment can be used to declare that the uintptr arguments to a
function may be converted from pointers, and that those pointers should
be considered to escape. This is used for the Call methods in
dll_windows.go that take uintptr arguments, because they call Syscall.

We can't treat these functions as we do syscall.Syscall, because unlike
Syscall they may cause the stack to grow. For Syscall we can assume that
stack arguments can remain on the stack, but for these functions we need
them to escape.

Fixes #16035.

Change-Id: Ia0e5b4068c04f8d303d95ab9ea394939f1f57454
Reviewed-on: https://go-review.googlesource.com/24551Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #8833

Change-Id: I4523a1de112ed02371504e27882659bce8028a45
Reviewed-on: https://go-review.googlesource.com/24745Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

These were helpful for some autogenerated code
I'm working with.

Change-Id: I7b89c69552ca99bf560a14bfbcd6bd238595ddf6
Reviewed-on: https://go-review.googlesource.com/24742Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Mostly constant folding rules, analogous to AMD64 ones. Along with
some simplifications.

Updates #15365.

Change-Id: If83bc1188bb05acb982ef3a1c21704c187e3eb24
Reviewed-on: https://go-review.googlesource.com/24210
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

As Josh mentioned in CL 24716, there has been requests for using SSA
for ARM. SSA can still be disabled by setting -ssa=0 for cmd/compile,
or partially enabled with GOSSAFUNC, GOSSAPKG, and GOSSAHASH.

Not enable SSA by default on NaCl, which is not supported yet.

Enable SSA-specific tests on ARM: live_ssa.go and nilptr3_ssa.go;
disable non-SSA tests: live.go, nilptr3.go, and slicepot.go.

Updates #15365.

Change-Id: Ic2ca8d166aeca8517b9d262a55e92f2130683a16
Reviewed-on: https://go-review.googlesource.com/23953
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Chase <drchase@google.com>

Fixes #16258.

Docs for Encode and EncodeValue do not mention that
nil pointers are not permitted hence we panic,
because Gobs encode values yet nil pointers have no value
to encode. It moves a comment that was internal to EncodeValue
to the top level to make it clearer to users what to expect
when they pass in nil pointers.
Supplements test TestTopLevelNilPointer.

Change-Id: Ie54f609fde4b791605960e088456047eb9aa8738
Reviewed-on: https://go-review.googlesource.com/24740Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Don't issue a copylock warning about a result type; the function may
return a composite literal with a zero value, which is OK.

Don't issue a copylock warning about a function call on the RHS, or an
indirection of a function call; the function may return a composite
literal with a zero value, which is OK.

Updates #16227.

Change-Id: I94f0e066bbfbca5d4f8ba96106210083e36694a2
Reviewed-on: https://go-review.googlesource.com/24711Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Updates #13372.

Change-Id: If383c14af14839a303425ba7b80b97e35ca9b698
Reviewed-on: https://go-review.googlesource.com/24750
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The comments were mostly duplicated; unify them.
Add a check that the required invariant holds.

Change-Id: I42fe09dcd1fac76d3c4e191f7a58c591c5ce429b
Reviewed-on: https://go-review.googlesource.com/24719
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Chase <drchase@google.com>

ITab is handled by decomposition.
The rule is vestigial. Remove it.

Change-Id: I6fdf3d14d466761c7665c7ea14f34ca0e1e3e646
Reviewed-on: https://go-review.googlesource.com/24718
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

The original intent of the code was to allow both with and without .git
suffix for now to allow a transition period. The noVCSSuffix check was a
copy pasta error.

Fixes #15979.

Change-Id: I3d39aba8d026b40fc445244d6d01d8bc1979d1e4
Reviewed-on: https://go-review.googlesource.com/24645Reviewed-by: Ian Lance Taylor <iant@golang.org>

Encode the size and the alignment into AuxInt of Zero and Move ops.
On AMD64, we simply don't look at the alignment. On ARM and PPC64, we
only generate aligned stores.

Updates #15365.

Change-Id: Ifdcc205c364f67c4516b9adebfe7d50d223b6863
Reviewed-on: https://go-review.googlesource.com/24511Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

If we don't mark them as needzero, we have a live pointer variable
containing possible garbage, which will baffle the GC.

Fixes #16249.

Change-Id: I7c423ceaca199ddd46fc2c23e5965e7973f07584
Reviewed-on: https://go-review.googlesource.com/24715
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Fixes #16243.

Change-Id: I207d1e8aa48abe453a23c709ccf4f8e07368595b
Reviewed-on: https://go-review.googlesource.com/24648
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The frontend may emit node with line number missing. In this case,
use the parent line number. Instead of changing every call site of
pushLine, do it in pushLine itself.

Fixes #16214.

Change-Id: I80390550b56e4d690fc770b01ff725b892ffd6dc
Reviewed-on: https://go-review.googlesource.com/24641Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Updates x/net/http2 to git rev b400c2e for https://golang.org/cl/24214,
"http2: add additional blacklisted ciphersuites"

Both TLS_RSA_WITH_AES_128_GCM_SHA256 & TLS_RSA_WITH_AES_256_GCM_SHA384
are now blacklisted, per http://httpwg.org/specs/rfc7540.html#BadCipherSuites

Change-Id: I8b9a7f4dc3c152d0675e196523ddd36111744984
Reviewed-on: https://go-review.googlesource.com/24684Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

+ test.

Fixes #16230

Change-Id: Idac995437146a9df9e73f094d2a31abc25b1fa62
Reviewed-on: https://go-review.googlesource.com/24681Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>