In reclaimChunk, the runtime is calling traceGCSweepDone() while holding the mheap
lock. traceGCSweepDone() can call traceEvent() and traceFlush(). These functions
not only can get various trace locks, but they may also do memory allocations
(runtime.newobject) that may end up getting the mheap lock. So, there may be
either a self-deadlock or a possible deadlock between multiple threads.

It seems better to release the mheap lock before calling traceGCSweepDone(). It is
fine to release the lock, since the operations to get the index of the chunk of
work to do are atomic. We already release the lock to call sweep, so there is no
new behavior for any of the callers of reclaimChunk.

With this change, mheap is a leaf lock (no other lock is ever acquired while it
is held).

Testing: besides normal all.bash, also ran all.bash with --long enabled, since
it does longer tests of runtime/trace.

Change-Id: I4f8cb66c24bb8d424f24d6c2305b4b8387409248
Reviewed-on: https://go-review.googlesource.com/c/go/+/207846Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

Updates #36019

Change-Id: I9fea2c3c5138e2233290979e4724f6e7b91da652
Reviewed-on: https://go-review.googlesource.com/c/go/+/213439Reviewed-by: Ian Lance Taylor <iant@golang.org>

In the previous CL we ensures that memmove writes pointers
atomically, so the concurrent GC won't observe a partially
updated pointer. This CL adds a test.

Change-Id: Icd1124bf3a15ef25bac20c7fb8933f1a642d897c
Reviewed-on: https://go-review.googlesource.com/c/go/+/212627Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This change converts TestCoverageWithCgo and TestCgoConsistentResults
to the script framework.

Change-Id: Ic5a13f6dd6099d3d73a5cda8cbc724a79a3d2c58
Reviewed-on: https://go-review.googlesource.com/c/go/+/212621
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: Ibc3cb3823bd1c1b80058076f2c9933dc729447a5
Reviewed-on: https://go-review.googlesource.com/c/go/+/213127
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Addressing comment in golang.org/cl/212620. I submitted the
change before I addressed the comment.

Change-Id: I008fdb4fed1e0b2d24d739991fe10122695b90b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/213419
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

It's already parallel, but we might as well convert it and
get rid of the testdata/src dircetory completely.

Updates #36320

Change-Id: I75e335b32d64a8ddedd65e4337949b729c9e0fbe
Reviewed-on: https://go-review.googlesource.com/c/go/+/212877
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

This change converts TestFatalInBenchmarkCauseNonZeroExitStatus,
TestBenchmarkLabels and TestWildCardsDoNotLookInUselessDirectories
to the script framework so they can run in parallel. These tests
used the testdata directory so they didn't call tg.parallel, because
they couldn't be sure the testdata directory wasn't being
modified while they were being run.

The tests are converted to the script framework instead of being modified
because the script framework tests are easier to read and are self-contained.

Also remove the directory src/cmd/go/testdata/src/badc. The testcase
that used it, "TestDisallowedCSourceFiles" was deleted in
golang.org/cl/19613.

Updates #17751

Change-Id: I0b9b417ae1a9b148067a3e5f8531229f3414f104
Reviewed-on: https://go-review.googlesource.com/c/go/+/212620
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Sprinkle in some more calls to tg.Parallel in the cmd/go
tests. These are the easy cases that don't operate in the
testdata directory.

I think the best thing to do for those tests that do operate
in testdata is to use the script tests. They're easier to
read and write, and jump into t.Parallel immediately.

Updates #17751

Change-Id: If8aeb8129cfdc0a9aa91f5a540f179790077fce5
Reviewed-on: https://go-review.googlesource.com/c/go/+/212618
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Add a link redirecting questions to the wiki page/forums

Change-Id: I05b784e6bb0c260cb01c4535ad05fb17ba80110e
GitHub-Last-Rev: a927ce5c69df7854ae919013b0e55ab4d356fc4c
GitHub-Pull-Request: golang/go#36413
Reviewed-on: https://go-review.googlesource.com/c/go/+/213440Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: Id1afafad2063d917fd55e08f0725ce3e93201c35
Reviewed-on: https://go-review.googlesource.com/c/go/+/212878
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Part of the effort to convert all non-parallel cmd/go tests to the script
framework.

Updates #17751
Updates #36320

Change-Id: I2bc0b1e5c03e2c49b5c79ac24a908a202840d5d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/212879
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

TestSelfConnect from CL 5650071 was renamed TestTCPSelfConnect in CL 21447.

Change-Id: I0de110dbe1da77bfba540a1b51c139f3bedae67f
Reviewed-on: https://go-review.googlesource.com/c/go/+/213437Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

This reverts commit 8adc1e00.

Reason for revert: The test added in this commit fails on several
builders.

Fixes #36389. Re-opens #33979.

Change-Id: I31191098c36af00f7688749b3376686673b3ac68
Reviewed-on: https://go-review.googlesource.com/c/go/+/213417
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: Ic16a0c6c1eabeba003b9cff620e2911078fd6cf8
Reviewed-on: https://go-review.googlesource.com/c/go/+/212813
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

It doesn't seem to be used anywhere.

Change-Id: If979b6d69c9bf5261afd980d96f67991c417d46d
Reviewed-on: https://go-review.googlesource.com/c/go/+/213218
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

For some reason the existing versions have additional padding - manually resync these
structs with those in x/sys/unix, also bringing in pollFd which does not currently
exist for linux/riscv64.

Cross checked with the output from 'go tool cgo -godefs' on a linux/riscv64 machine.

Updates #27532

Change-Id: I9fd2d3ad7222208a138773f4a9153c3c9cad7381
Reviewed-on: https://go-review.googlesource.com/c/go/+/212763
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

linux/riscv64 does not provide a renameat syscall and there is no SYS_RENAMEAT
defined in the syscall package. Provide Renameat as a wrapper around renameat2
instead.

Updates #27532

Change-Id: I4864bdf0055e4272920583dcfb0efe2fd40adcbc
Reviewed-on: https://go-review.googlesource.com/c/go/+/212762
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

RISCV has no instruction to store an immediate value to memory, or to
subtract an immediate value. An immediate needs to be moved to a register
first, or in the case of $0, the zero value register (ZERO or R0) can be
used instead. Restore the original riscv-go code so that it compiles.

Updates #27532

Change-Id: I3c60e6f385c59679252a710dbba153357a367516
Reviewed-on: https://go-review.googlesource.com/c/go/+/212761
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

Fixes #36396

Change-Id: I52190f450fa9ac52fbf4ecdc814e954dc29029cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/213377Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

ErrorUnresolved attempts to find the missing symbol in another ABI,
in order to provide more friendly error messages. However, in doing so
it checks the same ABI and can find the symbol reference for the symbol
that it is currently reporting the unresolved error for. Avoid this by
ignoring SXREF symbols, which is the same behaviour used when linking
is performed.

Fixes #33979

Change-Id: I3cb2477b2ad4baa7c2007323b983eb29404b0aac
Reviewed-on: https://go-review.googlesource.com/c/go/+/192597
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Joel Sing <joel@sing.id.au>

Move the CALL reloc symbol back to p.From.Sym, rather than p.To.Sym - while
p.To.Sym is the correct final location, the call to lowerJALR flips the p.To
and p.From addresses (and proves that this form of obj.Prog rewriting is not
a good idea).

Updates #27532

Change-Id: Iaf9fa24b05bda32b963f8d243401c6cd82c1355c
Reviewed-on: https://go-review.googlesource.com/c/go/+/212759Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Handle the rewriting of MOV pseudo-instructions in a separate pass. This allows
AMOV to be more readily used by other code, including AGETCALLERPC and ARET
implementations.

Updates #27532

Change-Id: Iea794121210048ed23ed0fb8f3c5e3cd5354a311
Reviewed-on: https://go-review.googlesource.com/c/go/+/212758Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

R11 a.k.a. REGTMP is the temp register used by the assembler. It
may be clobbered if the assembler needs to synthesize
instructions. In particular, in nanotime1/walltime1, the load of
global variable runtime.iscgo clobbers it. So, avoid using R11
to hold a long-lived value.

Fixes #36309.

Change-Id: Iec2ab9d664532cad8fbf58da17f580e64a744f62
Reviewed-on: https://go-review.googlesource.com/c/go/+/212641Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Andrew G. Morgan <agm@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

It was pointed out to me that the thread sanitizer library has many more
flags than the ones documented in this doc page. In particular, I was
able to make use of GORACE=atexit_sleep_ms=10 to reduce the amount that
'go test -race' will sleep before finishing.

I'm sure that this flag will be useful to others in the future, so add
it here. This is still not a complete list, but we can simply add useful
flags that work when we think they deserve a mention.

Change-Id: If199d36fd80a0945af90055d110519e5dba27361
Reviewed-on: https://go-review.googlesource.com/c/go/+/200863Reviewed-by: Heschi Kreinick <heschi@google.com>

Fixes #36297

Change-Id: I2623e9ee386644eddfa9a348ba368c5f1a81f893
Reviewed-on: https://go-review.googlesource.com/c/go/+/213134
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>

The literal string match had to be turned into a regexp, otherwise
pretty straightforward.

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: I46f62312f02dc9adf83ed91c6f807420d29fbb12
Reviewed-on: https://go-review.googlesource.com/c/go/+/212939
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: Icd62dc8db55bec52ad326bc370ee7e435aae2559
Reviewed-on: https://go-review.googlesource.com/c/go/+/212812
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

This conversion is a bit weird, because the original test runs in the cmd/go
directory, while the script test runs in the GOPATH directory. So even though
it's not necessary for the new test, it changes dircectory to $WORK, so that
its error message regexp can have four components like the original, just
changing the old gopath directory 'testdata' the new one 'gopath'.

Part of converting all tests to script framework to improve test parallelism.

Updates #36320
Updates #17751

Change-Id: Ie5b029c43dc22167278d3104b37c0b57c61326be
Reviewed-on: https://go-review.googlesource.com/c/go/+/212814
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

This test already runs in parallel, but still convert it to the
script framework so we can delete the testdata/src directory and
remove any ambiguity about which tests can run in parallel.

Updates #36320

Change-Id: I6470979bd8bad0631dc6ead0d4eb9c83878356e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/212815
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

The error that's tested in this test is also tested in list_test_err.txt
which uses go list -test -deps. Because both commands are just loading
packages, the difference is not meaningful.

Updates #36320
Updates #17751

Change-Id: Ie712a77d64e8985dd908a1afb515ed3ecc0a9985
Reviewed-on: https://go-review.googlesource.com/c/go/+/212937
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

TestPluginNonMain was broken before this change! (It provided the
wrong directory for testdep/p2: testdata/testdep/p2 instead of
testdata/src/testdep/p2).

Change-Id: Ib815f119bae1d758b500cd8ad82c016cb630d71e
Reviewed-on: https://go-review.googlesource.com/c/go/+/212938
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

This includes TestMatchesNoTestsDoesNotOverrideBuildFailure
and TestErrorMessageForSyntaxErrorInTestGoFileSaysFAIL.
Convert the tests that use the testdata/src/syntaxerror directory
to the script framework.

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: I2b2b616e8c124996ae8c8e5b737f15bb493ec588
Reviewed-on: https://go-review.googlesource.com/c/go/+/212816
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

root.html has been moved to the x/website repo in CL 180959
(commit golang/website@d83058ced3fadc3e8189107d2fb86c333c356b75).

conduct.html has been moved to the x/website repo in CL 207437
(commit golang/website@99763cba2e5b53679a96f69725f917feb319b799).

There should be only one copy, otherwise it may lead to confusion,
or changes made in the wrong place. This CL removes the old copies
from this repo since they're no longer used.

Updates #29206

Change-Id: I41adfb2c34ed3d870fb7a671f48ccc8f90863feb
Reviewed-on: https://go-review.googlesource.com/c/go/+/213157
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Found by running the go vet pass 'testinggoroutine' that
I started in CL 212920.

Change-Id: Ic9462fac85dbafc437fe4a323b886755a67a1efa
Reviewed-on: https://go-review.googlesource.com/c/go/+/213097
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Updates #33637

Change-Id: Ia782b3fdc5a8873606b96120a34c9bf194a1a346
Reviewed-on: https://go-review.googlesource.com/c/go/+/211197Reviewed-by: Jay Conrod <jayconrod@google.com>

Change-Id: Icd92d115e5d7f00b2100598baf2522ebebcdb223
Reviewed-on: https://go-review.googlesource.com/c/go/+/213125Reviewed-by: Ian Lance Taylor <iant@golang.org>

If a pointer write is not atomic, if the GC is running
concurrently, it may observe a partially updated pointer, which
may point to unallocated or already dead memory. Most pointer
writes, like the store instructions generated by the compiler,
are already atomic. But we still need to be careful in places
like memmove. In memmove, we don't know which bits are pointers
(or too expensive to query), so we ensure that all aligned
pointer-sized units are written atomically.

Fixes #36101.

Change-Id: I1b3ca24c6b1ac8a8aaf9ee470115e9a89ec1b00b
Reviewed-on: https://go-review.googlesource.com/c/go/+/212626Reviewed-by: Austin Clements <austin@google.com>

When a goroutine yields the remainder of its time to another goroutine
during direct semaphore handoff (as in an Unlock of a sync.Mutex in
starvation mode), it needs to signal that change to the execution
tracer. The discussion in CL 200577 didn't reach consensus on how best
to describe that, but pointed out that "traceEvGoSched / goroutine calls
Gosched" could be confusing.

Emit a "traceEvGoPreempt / goroutine is preempted" event in this case,
to allow the execution tracer to find a consistent event ordering
without being both specific and inaccurate about why the active
goroutine has changed.

Fixes #36186

Change-Id: Ic4ade19325126db2599aff6aba7cba028bb0bee9
Reviewed-on: https://go-review.googlesource.com/c/go/+/211797
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Starting with 2014 (golang.org/cl/46660043), we have enjoyed 6
consecutive years of the gopher. Now, the slice¹ of gophers is
ready to make its way into the next decade, as 2020 is the new
Year of the Gopher.

¹ https://en.wikipedia.org/w/index.php?title=List_of_English_terms_of_venery,_by_animal&oldid=932675028#G

Change-Id: I5f9598dbedb373bd13021964193fa9e44c67693e
Reviewed-on: https://go-review.googlesource.com/c/go/+/213017
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Symonds <dsymonds@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>