Adds the new canMergeLoad function which can be used by rules to
decide whether a load can be merged into an operation. The function
ensures that the merge will not reorder the load relative to memory
operations (for example, stores) in such a way that the block can no
longer be scheduled.

This new function enables transformations such as:

MOVD 0(R1), R2
ADD  R2, R3

to:

ADD  0(R1), R3

The two-operand form of the following instructions can now read a
single memory operand:

 - ADD
 - ADDC
 - ADDW
 - MULLD
 - MULLW
 - SUB
 - SUBC
 - SUBE
 - SUBW
 - AND
 - ANDW
 - OR
 - ORW
 - XOR
 - XORW

Improves SHA3 performance by 6-8%.

Updates #15054.

Change-Id: Ibcb9122126cd1a26f2c01c0dfdbb42fe5e7b5b94
Reviewed-on: https://go-review.googlesource.com/29272
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Inspired by Alberto Donizetti's observations in
https://go-review.googlesource.com/#/c/30099/.

name                 old time/op  new time/op  delta
DecimalConversion-8   138µs ± 1%   136µs ± 2%  -1.85%  (p=0.000 n=10+10)

10 runs each, measured on a Mac Mini, 2.3 GHz Intel Core i7.

Performance improvements varied between -1.25% to -4.4%; -1.85% is
about in the middle of the observed improvement. The generated code
is slightly shorter in the inner loops of the conversion code.

Change-Id: I10fb3b2843da527691c39ad5e5e5bd37ed63e2fa
Reviewed-on: https://go-review.googlesource.com/31250Reviewed-by: Alan Donovan <adonovan@google.com>

GC assists retry if preempted or if they fail to park. However, on the
retry path they currently use stale statistics. In particular, the
retry can use "debtBytes", but debtBytes isn't updated when the debt
changes (since other than retries it is only used once). Also, though
less of a problem, the if the assist ratio has changed while the
assist was blocked, the retry will still use the old assist ratio.

Fix all of this by simply making the retry jump back to where we
compute these statistics, rather than just after.

Change-Id: I2ed8b4f0fc9f008ff060aa926f4334b662ac7d3f
Reviewed-on: https://go-review.googlesource.com/30701Reviewed-by: Rick Hudson <rlh@golang.org>

This puts all of the assist queue-related code together and makes it
easier to modify how the assist queue works.

Change-Id: Id54e06702bdd5a5dd3fef2ce2c14cd7ca215303c
Reviewed-on: https://go-review.googlesource.com/30700Reviewed-by: Rick Hudson <rlh@golang.org>

It's pretty simple.  For:
  e = (interface{})(i)
Do:
  tmp = i.itab
  if tmp != nil {
    tmp = tmp.typ_ // load type from itab
  }
  e = eface{tmp, i.data}

It is smaller and faster than calling the runtime.

Change-Id: I0ad27f62f4ec0b6cd53bc8530e4da0eae3e67a6c
Reviewed-on: https://go-review.googlesource.com/31260
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

getArgInfo for reflect.makeFuncStub and reflect.methodValueCall is
necessarily special. These have dynamically determined argument maps
that are stored in their context (that is, their *funcval). These
functions are written to store this context at 0(SP) when called, and
getArgInfo retrieves it from there.

This technique works if getArgInfo is passed an active call frame for
one of these functions. However, getArgInfo is also used in
tracebackdefers, where the "call" is not a true call with an active
stack frame, but a deferred call. In this situation, getArgInfo
currently crashes because tracebackdefers passes a frame with sp set
to 0. However, the entire approach used by getArgInfo is flawed in
this situation because the wrapper has not actually executed, and
hence hasn't saved this metadata to any stack frame.

In the defer case, we know the *funcval from the _defer itself, so we
can fix this by teaching getArgInfo to use the *funcval context
directly when its available, and otherwise get it from the active call
frame.

While we're here, this commit simplifies getArgInfo a bit by making it
play more nicely with the type system. Rather than decoding the
*reflect.methodValue that is the wrapper's context as a *[2]uintptr,
just write out a copy of the reflect.methodValue type in the runtime.

Fixes #16331. Fixes #17471.

Change-Id: I81db4d985179b4a81c68c490cceeccbfc675456a
Reviewed-on: https://go-review.googlesource.com/31138
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

If morestack runs on the g0 or gsignal stack, it currently performs
some abort operation that typically produces a signal (e.g., it does
an INT $3 on x86). This is useful if you're running in a debugger, but
if you're not, the runtime tries to trap this signal, which is likely
to send the program into a deeper spiral of collapse and lead to very
confusing diagnostic output.

Help out people trying to debug without a debugger by making morestack
print an informative message before blowing up.

Change-Id: I2814c64509b137bfe20a00091d8551d18c2c4749
Reviewed-on: https://go-review.googlesource.com/31133
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Per discussion on #12808, it's a bit odd that if you do

	CGO_ENABLED=0 ./make.bash

then you get a toolchain that still tries to use cgo.
So make the CGO_ENABLED setting propagate into
the resulting toolchain as the default setting for that
environment variable, like we do with other variables
like CC and GOROOT.

No reasonable way to test automatically, but I did
test by hand that after the above command, 'go env'
shows CGO_ENABLED=0; before it showed CGO_ENABLED=1.

Fixes #12808.

Change-Id: I26a2fa6cc00e73bde8af7469270b27293392ed71
Reviewed-on: https://go-review.googlesource.com/31141
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This improves the performance for byte.Compare by rewriting
the cmpbody function in runtime/asm_ppc64x.s.  The previous code
had a simple loop which loaded a pair of bytes and compared them,
which is inefficient for long buffers.  The updated function checks
for 8 or 32 byte chunks and then loads and compares double words where
possible.

Because the byte.Compare result indicates greater or less than,
the doubleword loads must take endianness into account, using a
byte reversed load in the little endian case.

Fixes #17433

benchmark                                   old ns/op     new ns/op     delta
BenchmarkBytesCompare/8-16                  13.6          7.16          -47.35%
BenchmarkBytesCompare/16-16                 25.7          7.83          -69.53%
BenchmarkBytesCompare/32-16                 38.1          7.78          -79.58%
BenchmarkBytesCompare/64-16                 63.0          10.6          -83.17%
BenchmarkBytesCompare/128-16                112           13.0          -88.39%
BenchmarkBytesCompare/256-16                211           28.1          -86.68%
BenchmarkBytesCompare/512-16                410           38.6          -90.59%
BenchmarkBytesCompare/1024-16               807           60.2          -92.54%
BenchmarkBytesCompare/2048-16               1601          103           -93.57%

Change-Id: I121acc74fcd27c430797647b8d682eb0607c63eb
Reviewed-on: https://go-review.googlesource.com/30949Reviewed-by: David Chase <drchase@google.com>

To match the language spec, strconv.Unquote needs to strip carriage
returns from the raw string.

Also fixes TestUnquote to not be a noop.

Fixes #15997

Change-Id: I2456f50f2ad3830f37e545f4f6774ced9fe609d7
Reviewed-on: https://go-review.googlesource.com/31210Reviewed-by: Robert Griesemer <gri@golang.org>

The assembly in math/big may contain instructions that the bootstrap
compiler does not support. Disable it using the math_big_pure_go
build tag.

Fixes #17484.

Change-Id: I766cab6a888721ab4ed76ebdbfc87ad4e919ec41
Reviewed-on: https://go-review.googlesource.com/31142
Run-TryBot: Michael Munday <munday@ca.ibm.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The relevant benchmark (on an Intel i7-4510U machine):

name                      old time/op  new time/op  delta
FormatFloat/Slowpath64-4  68.6µs ± 0%  44.1µs ± 2%  -35.71%  (p=0.000 n=13+15)

Change-Id: I67eb0e81ce74ed57752d0280059f91419f09e93b
Reviewed-on: https://go-review.googlesource.com/30099Reviewed-by: Robert Griesemer <gri@golang.org>

This change imports the chacha20poly1305 and poly1305 packages from
x/crypto at 5f4e837b98443e9e7a65072235205993af565d85. These packages
will be used to support the ChaCha20-Poly1305 AEAD in crypto/tls.

Change-Id: I1a38d671ef9aeff3bc41e3924655883d465a5617
Reviewed-on: https://go-review.googlesource.com/30956Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Sometimes .git is a plain file; maybe others will follow.
This CL matches CL 21430, made in x/tools/go/vcs.

The change in the Swift test case makes the test case
pass by changing the test to match current behavior,
which I assume is better than the reverse.
(The test only runs locally and without -short, so the
builders are not seeing this particular failure.)

For #10322.

Change-Id: Iccd08819a01c5609a2880b9d8a99af936e20faff
Reviewed-on: https://go-review.googlesource.com/30948
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This change adds support for trampolines on ppc64x when using
internal linking, in the case where the offset to the branch
target is larger than what fits in the field provided by the
branch instruction.

Fixes #16665

Change-Id: Icfee72910f38c94588d2adce517b64dee6176145
Reviewed-on: https://go-review.googlesource.com/30850Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

The driver.Valuer interface lets types map their Go representation to
a suitable database/sql/driver.Value.

If a user defines the Value method with a value receiver, such as:

    type MyStr string

    func (s MyStr) Value() (driver.Value, error) {
        return strings.ToUpper(string(s)), nil
    }

Then they can't use (*MyStr)(nil) as an argument to an SQL call via
database/sql, because *MyStr also implements driver.Value, but via a
compiler-generated wrapper which checks whether the pointer is nil and
panics if so.

We now accept (*MyStr)(nil) and map it to "nil" (an SQL "NULL")
if the Valuer method is implemented on MyStr instead of *MyStr.

If a user implements the driver.Value interface with a pointer
receiver, they retain full control of what nil means:

    type MyStr string

    func (s *MyStr) Value() (driver.Value, error) {
        if s == nil {
            return "missing MyStr", nil
        }
        return strings.ToUpper(string(*s)), nil
    }

Adds tests for both cases.

Fixes #8415

Change-Id: I897d609d80d46e2354d2669a8a3e090688eee3ad
Reviewed-on: https://go-review.googlesource.com/31259
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Delete vendored copy.

Change-Id: I06e9d3b709553a1a8d06275e99bd8f617aac5788
Reviewed-on: https://go-review.googlesource.com/31011Reviewed-by: Ian Lance Taylor <iant@golang.org>

This allows use of newer math/big (and later debug/pe)
without maintaining a vendored copy somewhere in cmd.

Use for math/big, deleting cmd/compile/internal/big.

Change-Id: I2bffa7a9ef115015be29fafdb02acc3e7a665d11
Reviewed-on: https://go-review.googlesource.com/31010Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1. Define behavior for Unmarshal of JSON null into Unmarshaler and
TextUnmarshaler. Specifically, an Unmarshaler will be given the
literal null and can decide what to do (because otherwise
json.RawMessage is impossible to implement), and a TextUnmarshaler
will be skipped over (because there is no text to unmarshal), like
most other inappropriate types. Document this in Unmarshal, with a
reminder in UnmarshalJSON about handling null.

2. Test all this.

3. Fix the TextUnmarshaler case, which was returning an unmarshalling
error, to match the definition.

4. Fix the error that had been used for the TextUnmarshaler, since it
was claiming that there was a JSON string when in fact the problem was
NOT having a string.

5. Adjust time.Time and big.Int's UnmarshalJSON to ignore null, as is
conventional.

Fixes #9037.

Change-Id: If78350414eb8dda712867dc8f4ca35a9db041b0c
Reviewed-on: https://go-review.googlesource.com/30944Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The CloseWrite method sends a close_notify alert record to the other
side of the connection. This record indicates that the sender has
finished sending on the connection. Unlike the Close method, the sender
may still read from the connection until it recieves a close_notify
record (or the underlying connection is closed). This is analogous to a
TCP half-close.

Updates #8579

Change-Id: I9c6bc193efcb25cc187f7735ee07170afa7fdde3
Reviewed-on: https://go-review.googlesource.com/25159Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

For #16360.

Change-Id: I99d1e5ab1f814f65b3066a498158a442f1bd477f
Reviewed-on: https://go-review.googlesource.com/31137
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Copies utf8 constants and EncodeRune implementation from unicode/utf8.

Adds a new decoderune implementation that is used by the compiler
in code generated for ranging over strings. It does not handle
ASCII runes since these are handled directly before calls to decoderune.

The DecodeRuneInString implementation from unicode/utf8 is not used
since it uses a lookup table that would increase the use of cpu caches.

Adds more tests that check decoding of valid and invalid utf8 sequences.

name                              old time/op  new time/op  delta
RuneIterate/range2/ASCII-4        7.45ns ± 2%  7.45ns ± 1%     ~     (p=0.634 n=16+16)
RuneIterate/range2/Japanese-4     53.5ns ± 1%  49.2ns ± 2%   -8.03%  (p=0.000 n=20+20)
RuneIterate/range2/MixedLength-4  46.3ns ± 1%  41.0ns ± 2%  -11.57%  (p=0.000 n=20+20)

new:
"".decoderune t=1 size=423 args=0x28 locals=0x0
old:
"".charntorune t=1 size=666 args=0x28 locals=0x0

Change-Id: I1df1fdb385bb9ea5e5e71b8818ea2bf5ce62de52
Reviewed-on: https://go-review.googlesource.com/28490
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Referencing RFC 7230 Section 3.3.2, this CL
deduplicates multiple identical Content-Length headers
of a message or rejects the message as invalid if the
Content-Length values differ.

Fixes #16490

Change-Id: Ia6b0f58ec7d35710b11a36113d2bd9128f693f64
Reviewed-on: https://go-review.googlesource.com/31252Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Deadlines aren't implemented on Plan 9 yet.

Updates #17477.

Change-Id: I44ffdbef97276dfec56547e5189672b7da24bfc1
Reviewed-on: https://go-review.googlesource.com/31188Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: David du Colombier <0intro@gmail.com>

The incorrect table was used for estimating output size.
This can give suboptimal selection of entropy encoder in rare cases.

Change-Id: I8b358200f2d1f9a3f9b79a44269d7be704e1d2d9
Reviewed-on: https://go-review.googlesource.com/31172Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #16736

Change-Id: I335d201e3f6738d838de3881087cb640fc7670e8
Reviewed-on: https://go-review.googlesource.com/30578
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Modify the new Context methods to take a name-value driver struct.
This will require more modifications to drivers to use, but will
reduce the overall number of structures that need to be maintained
over time.

Fixes #12381

Change-Id: I30747533ce418a1be5991a0c8767a26e8451adbd
Reviewed-on: https://go-review.googlesource.com/30166Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

In ReadRune store the size of the rune that was read into lastRead
to avoid the need to call DecodeRuneLast in UnreadRune.

fmt:
name        old time/op  new time/op  delta
ScanInts-4   481µs ± 4%   458µs ± 3%  -4.64%  (p=0.000 n=20+20)

Change-Id: I500848e663a975f426402a4b3d27a541e5cac06c
Reviewed-on: https://go-review.googlesource.com/28817Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Updates #16456

Change-Id: Ifea651ea3ece2267a6f0c1638181d6ddd9248a9f
Reviewed-on: https://go-review.googlesource.com/31181Reviewed-by: Ian Lance Taylor <iant@golang.org>

Flesh out nacl's fake network system to match how all the other
platforms work: all other systems' SetReadDeadline and
SetWriteDeadline affect currently-blocked read & write calls.
This was documented in golang.org/cl/30164 because it was the status
quo and existing packages relied on it. (notably the net/http package)

And add a test.

Change-Id: I074a1054dcabcedc97b173dad5e827f8babf7cfc
Reviewed-on: https://go-review.googlesource.com/31178
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Template.escape makes the assumption that t.Lookup(t.Name()) is t
(escapeTemplate looks up the associated template by name and sets
escapeErr appropriately).

This assumption did not hold for a Cloned template, because the template
associated with t.Name() was a second copy of the original.

Add a test for the assumption that t.Lookup(t.Name()) == t.

One effect of this broken assumption was #16101: parallel Executes
racily accessed the template namespace because each Execute call saw
t.escapeErr == nil and re-escaped the template concurrently with read
accesses occurring outside the namespace mutex.

Add a test for this race.

Related to #12996 and CL 16104.

Fixes #16101

Change-Id: I59831d0847abbabb4ef9135f2912c6ce982f9837
Reviewed-on: https://go-review.googlesource.com/31092
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Fixes #17439

Change-Id: I7caa28519f38692f9ca306f0789cbb975fa1d7c4
Reviewed-on: https://go-review.googlesource.com/31112Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #16423

Change-Id: I9635db295be4d356d427adadd309084e16c4582f
Reviewed-on: https://go-review.googlesource.com/31255Reviewed-by: Ian Lance Taylor <iant@golang.org>

Exit code 3 is unprecedented and inconsistent with other failures here,
such as having no tool directory.

Fixes #17145

Change-Id: Ie7ed56494d4511a600214666ce3a726d63a8fd8e
Reviewed-on: https://go-review.googlesource.com/31253Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

No need to skip it. It passes.

Maybe it was fixed at some point.

Change-Id: I9848924aefda44f9b3a574a8705fa549d657f28d
Reviewed-on: https://go-review.googlesource.com/31177
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>

Change-Id: Ibae0be046c6a6596d3a98b094ec5f089bb68be7a
Reviewed-on: https://go-review.googlesource.com/31182Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I8a176ed9c7f59ebdfd39c1e2b88905f977179982
Reviewed-on: https://go-review.googlesource.com/31119Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Idca6115181960eed7a955027ee77a02decb4e7f2
Reviewed-on: https://go-review.googlesource.com/31179Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The error check patterns in this test are more complex than necessary
because f2 gets inlined into f1. This behavior isn't important to the
test, so disable inlining of f2 and simplify the error check patterns.

Change-Id: Ia8aee92a52f9217ad71b89b2931494047e8d2185
Reviewed-on: https://go-review.googlesource.com/31132
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Currently we use go:nowritebarrier in many places in proc.go.
go:notinheap and go:yeswritebarrierrec now let us use
go:nowritebarrierrec (the recursive form of the go:nowritebarrier
pragma) more liberally. Do so in proc.go

Change-Id: Ia7fcbc12ce6c51cb24730bf835fb7634ad53462f
Reviewed-on: https://go-review.googlesource.com/30942Reviewed-by: Rick Hudson <rlh@golang.org>