Currently, there is a single bit for LockOSThread, so two calls to
LockOSThread followed by one call to UnlockOSThread will unlock the
thread. There's evidence (#20458) that this is almost never what
people want or expect and it makes these APIs very hard to use
correctly or reliably.

Change this so LockOSThread/UnlockOSThread can be nested and the
calling goroutine will not be unwired until UnlockOSThread has been
called as many times as LockOSThread has. This should fix the vast
majority of incorrect uses while having no effect on the vast majority
of correct uses.

Fixes #20458.

Change-Id: I1464e5e9a0ea4208fbb83638ee9847f929a2bacb
Reviewed-on: https://go-review.googlesource.com/45752
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

The primary build tools cmd/asm, cmd/compile, and cmd/link are
built during cmd/dist bootstrap and then assumed by cmd/go to
be available for any future builds.

The only tool invoked by cmd/go during a build and not in this list
is cmd/cgo; instead of being built during cmd/dist and assumed by
cmd/go, cmd/go arranges to build cmd/cgo if needed as part of
the regular build. We got here because at the time cmd/go was written,
cmd/cgo was the only build tool written in Go (the others were in C),
and so it made some sense to put cmd/dist in charge of building
the C tools and to have custom code in cmd/go to build cmd/cgo
just in time for it to be used by a particular build.

This custom code has historically been quite subtle, though, because
the build of cmd/cgo inherits whatever build flags apply to the
build that wants to use cmd/cgo. If you're not careful,
"go install -race strings" might under the wrong circumstances
also install a race-enabled cmd/cgo binary, which is unexpected
at the least.

The custom code is only going to get more problematic as we
move toward more precise analysis of whether dependencies are
up-to-date. In that case, "go build -race strings" will check to
see if there is not just a cmd/cgo already but a race-enabled
cmd/cgo, which makes no sense.

Instead of perpetuating the special case, treat cgo like all the
other build tools: build it first in cmd/dist, and then assume it is present.
This simplifies cmd/go.

Building cmd/cgo during bootstrap also allows the default
build of cmd/cgo to be built using cgo, which may be necessary
on future essentially-cgo-only systems.

Change-Id: I414e22c10c9920f4e98f97fa35ff22058c0f143d
Reviewed-on: https://go-review.googlesource.com/68338
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

The loop finder doesn't return good information if it
encounters an irreducible loop.  Make a start on improving
this, and set a function-level flag to indicate when there
is such a loop (and the returned information might be flaky).

Use that flag to prevent the loop rotater from getting
confused; the existing code seems to depend on artifacts
of the previous loop-finding algorithm. (There is one
irreducible loop in the go library, in "inflate.go").

Change-Id: If6e26feab38d9b009d2252d556e1470c803bde40
Reviewed-on: https://go-review.googlesource.com/42150
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Change-Id: Ied42c2778899ce12cc256f0a124b77bf0e141aee
Reviewed-on: https://go-review.googlesource.com/68471
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Telling the truth about these will be important for
content-based staleness checks.

Change-Id: Iaed6ca6c945eb805d815156753a3e5dc48c6f0b9
Reviewed-on: https://go-review.googlesource.com/68336
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

Init functions are problematic because we want cmd/link to be
able to insert an import of runtime/cgo for external linking.
For all the other systems that just means putting runtime/cgo into
the binary. The linker is not set up to generate calls to init functions,
and luckily this one can be avoided entirely.

This means people don't have to import _ "runtime/cgo" in their
iOS programs anymore. The linker's default import is now enough.

This CL also adjusts cmd/go to record the linker's default import,
now that the explicit import is gone.

Change-Id: I81d23476663e03664f90d531c24db2e4f2e6c66b
Reviewed-on: https://go-review.googlesource.com/68490
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Historically, gc optimistically parsed the left-hand side of
assignments as expressions. Later, if it discovered a ":=" assignment,
it rewrote the parsed expressions as declarations.

This failed in the presence of dot imports though, because we lost
information about whether an imported object was named via a bare
identifier "Foo" or a normal qualified "pkg.Foo".

This CL fixes the issue by specially noding the left-hand side of ":="
assignments.

Fixes #22076.

Change-Id: I18190ecdb863112e7d009e1687e6112eec559921
Reviewed-on: https://go-review.googlesource.com/66810
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This applies the amd64-specific changes from CL 42611 to the s390x P256
implementation. The s390x implementation was disabled in CL 62292 and
this CL re-enables it.

Adam Langley's commit message from CL 42611:

The optimised P-256 includes a CombinedMult function, which doesn't do
dual-scalar multiplication, but does avoid an affine conversion for
ECDSA verification.

However, it currently uses an assembly point addition function that
doesn't handle exceptional cases.

Fixes #20215.

Change-Id: I2f6b532f495e85b8903475b4f64cc32a3b2f6769
Reviewed-on: https://go-review.googlesource.com/64290
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

We're going to start building cmd/cgo as part of the bootstrap,
and with it debug/elf, so the copy here needs to work with Go 1.4.
It does except for the use of the new io.SeekStart etc constants,
so remove that use.

Change-Id: Ib7fcf46e1e9060f96d2bacaaf349c9b0df347550
Reviewed-on: https://go-review.googlesource.com/68337
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

This shortens the args lists but also sets up better for
the content-based staleness changes.

While we're here, delete the now-unused Pkgpath method.

Change-Id: Ic60fa03efbc37a7c7fe9758a1cfa5dddef1a4151
Reviewed-on: https://go-review.googlesource.com/68335Reviewed-by: David Crawshaw <crawshaw@golang.org>

The following instructions were introduced in ARMv6, and the compiler
can do more optimization with them.

1. "MOVBS Rm@>i, Rd": rotates Rm 0/8/16/24 bits, does signed
byte extension to word, and writes the result to Rd.

2. "MOVHS Rm@>i, Rd": rotates Rm 0/8/16/24 bits, does signed
halfword extension to word, and writes the result to Rd.

3. "MOVBU Rm@>i, Rd": rotates Rm 0/8/16/24 bits, does unsigned
byte extension to word, and writes the result to Rd.

4. "MOVHU Rm@>i, Rd": rotates Rm 0/8/16/24 bits, does unsigned
half-word extension to word, and writes the result to Rd.

5. "XTAB Rm@>i, Rn, Rd": rotates Rm 0/8/16/24 bits, does signed
byte extension to word, adds Rn, and writes the result to Rd.

6. "XTAH Rm@>i, Rn, Rd": rotates Rm 0/8/16/24 bits, does signed
half-word extension to word, adds Rn, and writes the result to Rd.

7. "XTABU Rm@>i, Rn, Rd": rotates Rm 0/8/16/24 bits, does unsigned
byte extension to word, adds Rn, and writes the result to Rd.

8. "XTAHU Rm@>i, Rn, Rd": rotates Rm 0/8/16/24 bits, does unsigned
half-word extension to word, adds Rn, and writes the result to Rd.

Change-Id: I4306d7ebac93015d7e2e40d307f2c4271c03f466
Reviewed-on: https://go-review.googlesource.com/65790Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

For #22095

Change-Id: I2cb0d3e0aaf9f97952cf8dda0e99a4379e275020
Reviewed-on: https://go-review.googlesource.com/68332
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

For #22095

Change-Id: I07c288208d94dabae164c2ca0a067402a8e5c2e6
Reviewed-on: https://go-review.googlesource.com/68331
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Moves type symbol name mangling out of the object reader
and into a separate pass. Requires some care, as changing
the name of a type may require dealing with duplicate
symbols for the first time.

Disables DWARF for both plugins and programs that use plugin.Open,
because type manging is currently incompatible with the go.info.*
symbol generator in cmd/link. (It relies on the symbol names to
find type information.) A future fix for this would be moving the
go.info.* generation into the compiler, with the logic we use
for generating the type.* symbols.

Fixes #19529

Change-Id: I75615f8bdda86ff9e767e536d9aa36e15c194098
Reviewed-on: https://go-review.googlesource.com/67312
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

There is no cache here yet. This CL defines ActionID, Hash, and HashFile,
which the new content-based staleness code can use. Eventually we'll
put a real cache implementation here, but it's not necessary yet.

Change-Id: Ide433cb449f4dbe658694453f348c947642df79b
Reviewed-on: https://go-review.googlesource.com/67311Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

CL 41834 used approach suggested by Raymond Chen in
https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/
to implement os.Stat by getting Windows I/O manager
follow symbolic links.

Do the same for filepath.EvalSymlinks, when existing
strategy fails.

Updates #19922
Fixes #20506

Change-Id: I15f3d3a80256bae86ac4fb321fd8877e84d8834f
Reviewed-on: https://go-review.googlesource.com/55612Reviewed-by: Ian Lance Taylor <iant@golang.org>

(*sigctxt).fault() currently returns either uintptr, uint32, or uint64
depending on the platform. Make them all return uintptr.

For #10958 (but a nice change on its own).

Change-Id: I7813e779d0edcba112dd47fda776f4ce6e50e227
Reviewed-on: https://go-review.googlesource.com/68015
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Currently the linker figures out where runtime-gdb.py should be by
looking for the path to runtime/debug.go. However, debug.go contains
only a few symbols and can easily get dead-code eliminated entirely,
especially from simple binaries. When this happens, the resulting
binary lacks a reference to runtime-gdb.py, so the GDB helpers don't
get loaded.

Fix this by instead sniffing for runtime/proc.go. This contains
runtime.main and the scheduler, so it's not going anywhere.

Change-Id: Ie3380c77c840d28614fada68b8c5861625f2aff5
Reviewed-on: https://go-review.googlesource.com/68019
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

All of the callers want a *obj.LSym instead of a *types.Sym, and the
runtime type descriptors don't need Go source symbols anyway.

Passes toolstash-check.

Change-Id: I8ae4b64380fbb547857f49b42465118f41884eed
Reviewed-on: https://go-review.googlesource.com/68251
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

Change-Id: Ib042e472e62f48a6afaba1762beaf102a9b99cf5
Reviewed-on: https://go-review.googlesource.com/68290Reviewed-by: Russ Cox <rsc@golang.org>

Before CL 62530 fastrand always returned non-zero value, and one
condition in sema.go depends on this behavior.

fastrand is used to generate random weight for treap of sudog, and
it is checked against zero to verify sudog were inserted into treap or
wait queue.

Since its precision is not very important for correctness, lets just
always set its lowest bit in this place.

Updates #22047
Updates #21806

Change-Id: Iba0b56d81054e6ef9c49ffd293fc5d92a6a31e9b
Reviewed-on: https://go-review.googlesource.com/68050Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Ib42fabc6829b6033373c0378713733f88e73e73d
Reviewed-on: https://go-review.googlesource.com/68230Reviewed-by: Russ Cox <rsc@golang.org>

PlainAuth originally refused to send passwords to non-TLS servers
and was documented as such.

In 2013, issue #5184 was filed objecting to the TLS requirement,
despite the fact that it is spelled out clearly in RFC 4954.
The only possibly legitimate use case raised was using PLAIN auth
for connections to localhost, and the suggested fix was to let the
server decide: if it advertises that PLAIN auth is OK, believe it.
That approach was adopted in CL 8279043 and released in Go 1.1.

Unfortunately, this is exactly wrong. The whole point of the TLS
requirement is to make sure not to send the password to the wrong
server or to a man-in-the-middle. Instead of implementing this rule,
CL 8279043 blindly trusts the server, so that if a man-in-the-middle
says "it's OK, you can send me your password," PlainAuth does.
And the documentation was not updated to reflect any of this.

This CL restores the original TLS check, as required by RFC 4954
and as promised in the documentation for PlainAuth.
It then carves out a documented exception for connections made
to localhost (defined as "localhost", "127.0.0.1", or "::1").

Change-Id: I1d3729bbd33aa2f11a03f4c000e6bb473164957b
Reviewed-on: https://go-review.googlesource.com/68170
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

These are redundant with checking x.Sym.Pkg == localpkg.

Passes toolstash-check -all.

Change-Id: Iebe25f7932cd15a036141b468ad75c239abcdcf7
Reviewed-on: https://go-review.googlesource.com/66670
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Avoids generating useless equality and hash functions.

Shrinks cmd/go executable size on linux/amd64 by ~17kB.

Change-Id: Ifde5315cc5cbceb3a7260195c8803cace952359f
Reviewed-on: https://go-review.googlesource.com/66650
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

This can only lead to confusion.

Change-Id: Iae84c6404ab5eeb6950faa2364f97a017c67c506
Reviewed-on: https://go-review.googlesource.com/68110
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Simon Rawet <Simon@rawet.se>

This removes some of the []byte/string conversions currently
existing in the (un)marshaling methods of Int and Rat.

For Int we introduce a new function (*Int).setFromScanner() essentially
implementing the SetString method being given an io.ByteScanner instead
of a string. So we can handle the string case in (*Int).SetString with
a *strings.Reader and the []byte case in (*Int).UnmarshalText() with a
*bytes.Reader now avoiding the []byte/string conversion here.

For Rat we introduce a new function (*Rat).marshal() essentially
implementing the String method outputting []byte instead of string.
Using this new function and the same formatting rules as in
(*Rat).RatString we can implement (*Rat).MarshalText() without
the []byte/string conversion it used to have.

Change-Id: Ic5ef246c1582c428a40f214b95a16671ef0a06d9
Reviewed-on: https://go-review.googlesource.com/65950Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

It was only waiting 0.1 seconds for the two GCs it wanted.
Let it wait 1 second.

Change-Id: Ib3cdc8127cbf95694a9f173643c02529a85063af
Reviewed-on: https://go-review.googlesource.com/68151
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Before this change the ct == 0 check could never be true. Moreover the
values were not properly indirected.

Change-Id: Ice47e36e3492babc4b47d2f9099e8772be231c96
Reviewed-on: https://go-review.googlesource.com/68130Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Run-TryBot: Daniel Theophanes <kardianos@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Preparation for moving the object file reader to its own package.

For #22095

Change-Id: I31fe4a10a2c465f8ea4bf548f40918807e4ec6b5
Reviewed-on: https://go-review.googlesource.com/67314
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fix incorrect reference to string instead of byte slice.

Change-Id: I95553da32acfbcf5dde9613b07ea38408cb31ae8
Reviewed-on: https://go-review.googlesource.com/68090Reviewed-by: Ian Lance Taylor <iant@golang.org>

Also reduce the passed context from *Link to *sys.Arch, so fewer
data dependencies need to be wired through all the code dealing
with symbols.

For #22095

Change-Id: I50969405d6562c5152bd1a3c443b72413e9b70bc
Reviewed-on: https://go-review.googlesource.com/67313
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Update golang/go#22120

Change-Id: Ie7dbd0e7b01b116c960243a8cd3fa9fd121f317d
Reviewed-on: https://go-review.googlesource.com/68021Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

All current darwin architectures seem to take at least 100ms to dial a closed port,
and that was making the all.bash script fail.

Fixes #22062

Change-Id: Ib79c4b7a5db2373c95ce5d993cdcbee55cc0667f
Reviewed-on: https://go-review.googlesource.com/67350Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #19418

Change-Id: I98205f40c1915cd68a5d20438469ba06f1efb160
Reviewed-on: https://go-review.googlesource.com/67432
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Begin passing coutbuf by as a parameter. To make the initial plumbing
pass easier, it is also a field in the standard ctxt parameter.

Consolidate the byte writing functions into the OutBuf object.
The result is less architecture-dependent initialization.

To avoid plumbing out everywhere we want to report an error, move
handling of out file deletion to an AtExit function.

For #22095

Change-Id: I0863695241562e0662ae3669666c7922b8c846f9
Reviewed-on: https://go-review.googlesource.com/67318
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

For #22095

Change-Id: I9d1f0d93f8fd701a24af826dc903eea2bc235de2
Reviewed-on: https://go-review.googlesource.com/67317
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

No need to type this global as an unsafe.Pointer, we know
what type the referent is.

Change-Id: I7b1374065b53ccf1373754a21d54adbedf1fd587
Reviewed-on: https://go-review.googlesource.com/67990Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Latest macOS High Sierra changed how the wall time information
is exported into the commpage. Backward compatibility was partly
preserved, that is previous Go versions are basically forced to
go through a syscall which is much slower and is not able to
get nanosecond precision.

Implement the new commpage layout and wall time computation,
using a version check to fallback to the previous code on
older operating systems.

Fixes #22037

Change-Id: I8c2176eaca83a5d7be23443946a6b4c653ec7f68
Reviewed-on: https://go-review.googlesource.com/67332
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

cmd/cgo is special among the build tools because it is (re)built on demand
when needed for a package using cgo, to avoid additional bootstrap logic
elsewhere. (This is in contrast to cmd/compile, cmd/link, and so on, which
must be specially built before even invoking the go command.)

When the go command starts using content-based decisions about staleness,
it is important that the build of cmd/cgo never use -linkmode=external,
because that depends on runtime/cgo, which in turn depends on cmd/cgo.

Change-Id: I72a2be748606d1ed4b93a54f2a5c7084e87d5fbc
Reviewed-on: https://go-review.googlesource.com/67310Reviewed-by: Ian Lance Taylor <iant@golang.org>