For modular exponentiation, negative exponents can be handled using
the following relation.

for y < 0: x**y mod m == (x**(-1))**|y| mod m

First compute ModInverse(x, m) and then compute the exponentiation
with the absolute value of the exponent.  Non-modular exponentiation
with a negative exponent still returns 1.

Fixes #25865

Change-Id: I2a35986a24794b48e549c8de935ac662d217d8a0
Reviewed-on: https://go-review.googlesource.com/118562
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

This commit adds support for JavaScript callbacks back into
WebAssembly. This is experimental API, just like the rest of the
syscall/js package. The time package now also uses this mechanism
to properly support timers without resorting to a busy loop.

JavaScript code can call into the same entry point multiple times.
The new RUN register is used to keep track of the program's
run state. Possible values are: starting, running, paused and exited.
If no goroutine is ready any more, the scheduler can put the
program into the "paused" state and the WebAssembly code will
stop running. When a callback occurs, the JavaScript code puts
the callback data into a queue and then calls into WebAssembly
to allow the Go code to continue running.

Updates #18892
Updates #25506

Change-Id: Ib8701cfa0536d10d69bd541c85b0e2a754eb54fb
Reviewed-on: https://go-review.googlesource.com/114197Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

It's non-portable, and the test isn't hard to write without diff.
It still produces helpful output in case of trouble:

--- FAIL: TestCoverHTML (0.75s)
    cover_test.go:325: line 4 differs: got:
        	case &lt;-ch:<span class="cov0" title="0"></span>
        want:
        	case &lt;-ch:<span class="cov0" xitle="0"></span>

This makes the test operating-system independent.

Change-Id: Iff35f00cb76ba89bc1b93db01c6f994e74341f4a
Reviewed-on: https://go-review.googlesource.com/118795Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Instead of first looking for values of unnamed signature type, first
treat the types and builtins. All the remaining cases will be what we're
after.

Change-Id: I328e22ae0be1cccaeb45ed4ddaa360233d447e7e
Reviewed-on: https://go-review.googlesource.com/117835
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Robert Griesemer <gri@golang.org>

Handling of sign bit as defined by IEEE 754-2008, section 6.3:

When the sum of two operands with opposite signs (or the difference of
two operands with like signs) is exactly zero, the sign of that sum (or
difference) shall be +0 in all rounding-direction attributes except
roundTowardNegative; under that attribute, the sign of an exact zero
sum (or difference) shall be −0. However, x+x = x−(−x) retains the same
sign as x even when x is zero.

This change handles the special case of Add/Sub resulting in exactly zero
when the rounding mode is ToNegativeInf setting the sign bit accordingly.

Fixes #25798

Change-Id: I4d0715fa3c3e4a3d8a4d7861dc1d6423c8b1c68c
Reviewed-on: https://go-review.googlesource.com/117495
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Inlining of switch statements into a RETURNed expression
can sometimes lead to the switch being walked twice, which
results in a miscompiled switch statement. The bug depends
on:

1) multiple results
2) named results
3) a return statement whose expression includes a call to a
function containing a switch statement that is inlined.

It may also be significant that the default case of that
switch is a panic(), though that's not proven.

Rearranged the walk case for ORETURN so that double walks are
not possible.  Added a test, because this is so fiddly.
Added a check against double walks, verified that it fires
w/o other fix.

Fixes #25776.

Change-Id: I2d594351fa082632512ef989af67eb887059729b
Reviewed-on: https://go-review.googlesource.com/118318
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

NewReader cannot return an error. This behaviour is kept.
NextPart returns EOF when boundary is empty.
RFC 2046 does not allow it. The fix is to return an error
on the call of NextPart.

Fixes #23170

Change-Id: I775afd3f93e8b56e6cb274bc5c9de362a18bcc3c
Reviewed-on: https://go-review.googlesource.com/118822Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Follow the convertion (https://golang.org/s/generatedcode) for generated
code in alldocs.go

Change-Id: I03985de20363ba8e09a5a624a931090ec8d196e6
Reviewed-on: https://go-review.googlesource.com/118816
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The TestMapping test invokes the go tool in an exec.Command by
directly hard-coding a "go" string for the command. This can cause
test failures on systems where the "go" command points to an old
toolchain where the test is not supposed to work.

Use testenv.GoToolPath instead.

Also call 'go run' directly on the mappingtest/main.go file instead of
go-running the directory.

Change-Id: Ib91877c021209cbf4da50a561737d7a9d42c6adc
Reviewed-on: https://go-review.googlesource.com/118662
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

TestFifoEOF fails on android because the mkfifo syscall is not allowed:

--- FAIL: TestFifoEOF (0.00s)
    fifo_test.go:39: permission denied

Change-Id: I007ff359831525add39cec34de4b3d3cd3adb047
Reviewed-on: https://go-review.googlesource.com/118815
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Follow the convertion (https://golang.org/s/generatedcode) for generated
code.

Change-Id: I4ac8b99ac45f25dd2399d048ea831489e5394984
Reviewed-on: https://go-review.googlesource.com/118821
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Current SendFile implementation assumes that TransmitFile starts from
the current file position. But that appears not true for Windows 10
Version 1803.

TransmitFile documentation

https://msdn.microsoft.com/en-us/library/windows/desktop/ms740565(v=vs.85).aspx

suggests, "You can use the lpOverlapped parameter to specify a 64-bit
offset within the file at which to start the file data transfer by
setting the Offset and OffsetHigh member of the OVERLAPPED structure."

Do as it advises.

Fixes #25722

Change-Id: I241d3bf76d0d5590d4df27c6f922d637068232fb
Reviewed-on: https://go-review.googlesource.com/117816
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Godoc expects text after a header, not code.

Change-Id: I99f412ad15e10bf9cea0dbd19019ed6ce477736c
Reviewed-on: https://go-review.googlesource.com/117595Reviewed-by: Rob Pike <r@golang.org>

This change updates the go tool's documentation under the section
"Generate Go files by processing source" to mention the convention that
generated source files should have a line of text that matches the
following regular expression:

    ^// Code generated .* DO NOT EDIT\.$

Previously, the canonical documentation for this convention
(https://golang.org/s/generatedcode) referenced Rob Pike's comment at
https://golang.org/issue/13560#issuecomment-288457920. This change
merely moves that information to a more visible place.

Updates #25433.

Change-Id: I804d95d307d1dc68cb28da3750ebe9090178c474
Reviewed-on: https://go-review.googlesource.com/118756Reviewed-by: Rob Pike <r@golang.org>

It was apparently waiting on CL 36942, which was submitted.

Fixes #21416

Change-Id: I8f4ccc5a3176070abf0df019c82700c5761b5f53
Reviewed-on: https://go-review.googlesource.com/117055
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This avoids name conflicts when two identical packages use cgo.
This can happen in practice when the same package is vendored multiple
times in a single build.

Fixes #23555

Change-Id: I9f0ec6db9165dcf9cdf3d314c668fee8ada18f9c
Reviewed-on: https://go-review.googlesource.com/118739
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Ensure that compiler error suggestions after case insensitive
field lookups don't mistakenly reported unexported fields if
those fields aren't in the local package being processed.

Fixes #25727

Change-Id: Icae84388c2a82c8cb539f3d43ad348f50a644caa
Reviewed-on: https://go-review.googlesource.com/117755
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #23720

Change-Id: I28e0c16503bc043f793e0dab19668f7a66313312
Reviewed-on: https://go-review.googlesource.com/118737
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The current implementation does not support calling C variadic
functions (as discussed in #975). Document that.

Fixes #23537

Change-Id: If4c684a3d135f3c2782a720374dc4c07ea66dcbb
Reviewed-on: https://go-review.googlesource.com/90415Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I9154df128b349c102854bb0f21e4c313685dd0e6
Reviewed-on: https://go-review.googlesource.com/118659Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #25876

Change-Id: I149dbb2afef13cc13fb5722d930377ed918d7e3c
Reviewed-on: https://go-review.googlesource.com/118717Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #25849

Change-Id: I09ee928b462ab538a9d38c4e317eaeb8856919f2
Reviewed-on: https://go-review.googlesource.com/118335Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

Fixes #25472

Change-Id: Idb72ed06a3dc43c49ab984a80f8885352b036465
Reviewed-on: https://go-review.googlesource.com/118695Reviewed-by: Rob Pike <r@golang.org>

The function parseInitData appears to be unused. Deleted.

Change-Id: I7d4efed9d2519cfbd0ba03d89b45add8b314ea84
Reviewed-on: https://go-review.googlesource.com/118556
Run-TryBot: Robert Griesemer <gri@golang.org>
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Display just a few columns in ssa.html, other
columns can be expanded by clicking on collapsed column.

Use sans serif font for the text, slightly smaller font size
for non program text.

Fixes #25286

Change-Id: I1094695135401602d90b97b69e42f6dda05871a2
Reviewed-on: https://go-review.googlesource.com/117275
Run-TryBot: Yury Smolsky <yury@smolsky.by>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

As mentioned in #25845, port CL 46474 from golang.org/x/sys/unix to the
syscall package.

Currently Linux' fchmodat(2) syscall implementation doesn't support the
flags parameter (though it might in future versions [1]). Fchmodat in
the syscall package takes the parameter and (wrongly) passes it on to the
syscall which will ignore it.

According to the POSIX.1-2008 manual page [2], AT_SYMLINK_NOFOLLOW is
the only valid value for the flags parameter and EOPNOTSUPP should be
returned in case changing the mode of a symbolic link is not supported
by the underlying system. EINVAL should be returned for any other value
of the flags parameter.

  [1] https://patchwork.kernel.org/patch/9596301/
  [2] http://pubs.opengroup.org/onlinepubs/9699919799/functions/chmod.html

Updates #20130
Updates #25845

Change-Id: I1021dd0e6a4f4cb3557cb1c1b34dd618c378cda6
Reviewed-on: https://go-review.googlesource.com/118658Reviewed-by: Ian Lance Taylor <iant@golang.org>

The Darwin kqueue implementation doesn't report any event when the
last writer for a fifo is closed.

Fixes #24164

Change-Id: Ic2c47018ef1284bf2e26379f8dd7646edaad4d05
Reviewed-on: https://go-review.googlesource.com/118566Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Ie97c9c9163f5af7b4768c34faac726e21627aa79
Reviewed-on: https://go-review.googlesource.com/118660
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

kqueue, kevent, closeonexec, setitimer, with sysctl and fcntl helpers.

TODO:arm,arm64

Change-Id: I9386f377186d6ac7cb99064c524a67e0c8282eba
Reviewed-on: https://go-review.googlesource.com/118561Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

The test requires cgo

Change-Id: I1bffee5f187afcf4b7e27516451c56ddfc263a26
Reviewed-on: https://go-review.googlesource.com/118638Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This reverts commit bd837745.

Reason for revert: This broke ELF layout on arm, arm64, mips*, mips64*, ppc64*, and s390x.

Change-Id: I56a27b76e6f4b22ce39a99790af9116f8687eee9
Reviewed-on: https://go-review.googlesource.com/118675Reviewed-by: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #25852

Change-Id: I35c630367c8f1934dcffc0b0e08891d55a903518
Reviewed-on: https://go-review.googlesource.com/118560
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Bonventre <andybons@golang.org>

Like on other architectures, use rawSyscallNoError for Linux syscalls
that don't return an error and convert all applicable occurences of
RawSyscall to use it instead.

This was missed in CL 84485 because mkall.sh doesn't support
mipsx/mips64x, so add the corresponding entries as well.

Updates #22924

Change-Id: I762cbee0827140b9890c4a10830e0b4cd33de92f
Reviewed-on: https://go-review.googlesource.com/118655
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This commit changes wasm_exec.js to not depend on the existence of
performance.timeOrigin. The field is not yet supported on all
browsers, e.g. it is unavailable on Safari.

Change-Id: I6cd3834376c1c55424c29166fde1219f0d4d338f
Reviewed-on: https://go-review.googlesource.com/118617Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The pprof tool utilizes attributes of mapping entries
such as HasFunctions to determine whether the profile
includes necessary symbol information.
If none of the attributes is set, pprof tool tries to
read the corresponding binary to use for local symbolization.
If the binary doesn't exist, it prints out error messages.

Go runtime generated profiles without any of the attributes
set so the pprof tool always printed out the error messages.
The error messages became more obvious with the new
terminal support that uses red color for error messages.

Go runtime can symbolize all Go symbols and generate
self-contained profile for pure Go program. Thus, there
is no reason for the pprof tool to look for the copy of
the binary. So, this CL sets one of the attributes
(HasFunctions) true if all PCs in samples look fully
symbolized.

For non-pure Go program, however, it's possible that
symbolization of non-Go PCs is incomplete. In this case,
we need to leave the attributes all false so pprof can attempt
to symbolize using the local copy of the binary if available.
It's hard to determine whether a mapping includes non-Go
code. Instead, this CL checks PCs from collected samples.
If unsuccessful symbolization is observed, it skips setting
the HasFunctions attribute.

Fixes #25743

Change-Id: I5108be45bbc37ab486d145fa03e7ce37d88fad50
Reviewed-on: https://go-review.googlesource.com/118275
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This is needed in addition to CL 110066 in order to be able to generate
Go type definitions for linux/riscv64 in the golang.org/x/sys/unix
package.

Change-Id: I4a27e6424aaea63283b55bd4f73b958b41f29d72
Reviewed-on: https://go-review.googlesource.com/118618
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
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Reviewed-by: Ian Lance Taylor <iant@golang.org>

CL 108156 added -cgo and -export,
but in the usage line it added -cgo and -list.
CL 117015 correctly added -export to the usage line.
All that remains is to remove -list.

Change-Id: I8cc5cfc78bc6b52080ae1b861f92620a8f18b53f
Reviewed-on: https://go-review.googlesource.com/118375
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I9d2d25df067ca573589db5ff18296a5ec33866be
Reviewed-on: https://go-review.googlesource.com/118595Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I3ac25cf1770b5ac0d36690c37615b3badd27463d
Reviewed-on: https://go-review.googlesource.com/118455Reviewed-by: Rob Pike <r@golang.org>

Change-Id: Iea5c705dd58f9b83fbeb0500defcc08c34716169
GitHub-Last-Rev: 35702c784e2329fe3e44947430d246f8cdb04645
GitHub-Pull-Request: golang/go#25858
Reviewed-on: https://go-review.googlesource.com/118536Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>