The 2-instruction TLS access sequence
	MOVQ TLS, BX
	MOVQ 0(BX)(TLS*1), BX
is not async preemptible, as if it is preempted and resumed on a
different thread, the TLS address may become invalid.

May fix #35349. (This is a rare failure and I haven't been able
to reproduce it.)

Change-Id: Ie1a366fd0d7d73627dc62ee2de01c0aa09365f2b
Reviewed-on: https://go-review.googlesource.com/c/go/+/206903
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Austin Clements <austin@google.com>

When we receive a signal, if G is nil we call badsignal, which
calls needm. When cgo is not used, there is no extra M, so needm
will just hang. In this situation, even GOTRACEBACK=crash cannot
get a stack trace, as we're in the signal handler and cannot
receive another signal (SIGQUIT).

Instead, just crash.

For #35554.
Updates #34391.

Change-Id: I061ac43fc0ac480435c050083096d126b149d21f
Reviewed-on: https://go-review.googlesource.com/c/go/+/206959
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The existing implementation is erroneously assume that having no
deadline in context.Context means that time returned from Deadline
method will have IsZero() == true. But technically speaking this is an
invalid assumption. The context.Context interface specification doesn't
specify what time should be returned from Deadline method when there is
no deadline set. It only specifies that second result of Deadline should
be false.

Fixes #35594

Change-Id: Ife00aad77ab3585e469f15017550ac6c0431b140
Reviewed-on: https://go-review.googlesource.com/c/go/+/207297
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

When -trimpath is used, packages built from the module cache still
have debug into that contains the module path and version. Only the
module cache directory is stripped.

With this CL, we now include the module path and version in the cache
key for build actions.

Fixes #35412

Change-Id: I1956592d0d86fcea2cca7c5fc8957e83543d6aa2
Reviewed-on: https://go-review.googlesource.com/c/go/+/207317
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Updates #28387
Updates #30316
Fixes #35574

Change-Id: I21c9e18573909e092ed8dcec91b8542bb97e9f5a
Reviewed-on: https://go-review.googlesource.com/c/go/+/207263Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The NDK is switching to ldd, and will stop including the gold linker.

Change-Id: If74168017c9874134b34010906ab1d94001528b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/206840
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

tryAdd shouldn't succeed (and accept the new frame) if the last
existing frame on the deck is not an inlined frame.

For example, when we see the followig stack
[300656 300664 300655 300664]

with each PC corresponds to

[{PC:300656 Func:nil Function:runtime.nanotime File:/workdir/go/src/runtime/time_nofake.go Line:19 Entry:300416 {0x28dac8 0x386c80}}]
[{PC:300664 Func:0x28dac8 Function:runtime.checkTimers File:/workdir/go/src/runtime/proc.go Line:2623 Entry:300416 {0x28dac8 0x386c80}}]
[{PC:300655 Func:nil Function:runtime.nanotime File:/workdir/go/src/runtime/time_nofake.go Line:19 Entry:300416 {0x28dac8 0x386c80}}]
[{PC:300664 Func:0x28dac8 Function:runtime.checkTimers File:/workdir/go/src/runtime/proc.go Line:2623 Entry:300416 {0x28dac8 0x386c80}}]

PC:300656 and PC:300664 belong to a single location entry,
but the bug in the current tryAdd logic placed the entire stack into one
location entry.

Also adds tests - this crash is a tricky case to test because I think it
should happen with normal go code. The new TestTryAdd simulates it by
using fake call sequences. The test crashed without the fix.

Update #35538

Change-Id: I6d3483f757abf4c429ab91616e4def90832fc04a
Reviewed-on: https://go-review.googlesource.com/c/go/+/206958Reviewed-by: Keith Randall <khr@golang.org>

Fixes #35085

Change-Id: Ice611e1223392f687061a43fd4c2298ea22774fb
Reviewed-on: https://go-review.googlesource.com/c/go/+/207081
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Fixes #35492

Change-Id: I00dce8fd1228f809e0c61013ac4de7a5953cbbf9
Reviewed-on: https://go-review.googlesource.com/c/go/+/206997
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

'go build' now reports a more useful error when a relative path on the
command line points to a directory that doesn't exist or a directory
without .go files. Errors are generated by go/build.Context.ImportDir
instead of a vague call to base.Fatalf in modload.

Fixes #35414

Change-Id: I2642230c5e409107b98bb6d6c3a484d8d25b4147
Reviewed-on: https://go-review.googlesource.com/c/go/+/206902
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

It turns out that there is a path that initializes netpoll and opens
file descriptors before running the os/exec init function: on some
systems, the uses of NewFile when setting os.Stdin and friends can
initialize netpoll which can open file descriptors. This in itself
is not a problem, but when we check whether the new files are open
using os.NewFile, a side-effect is to put them into non-blocking mode.
This can then break future uses of netpoll.

Updates #35469
Fixes #35566

Change-Id: I1b2e2c943695d1c2d29496b050abbce9ee710a00
Reviewed-on: https://go-review.googlesource.com/c/go/+/207078Reviewed-by: Bryan C. Mills <bcmills@google.com>

The bash version of the test wrote intermediate files to its testdata directory.

Updates #28387
Updates #30316
Fixes #35536

Change-Id: Ib81b547d3c43e90df713a2172c8f399fefb53c68
Reviewed-on: https://go-review.googlesource.com/c/go/+/206901
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The bounds in the last carry branch were wrong as there
is no reason for len(u) >= n+n/2 to always hold true.

We also adjust test to avoid using a remainder of 1
(in which case, the last step of the algorithm computes
(qhatv+1) - qhatv which rarely produces a carry).

Change-Id: I69fbab9c5e19d0db1c087fbfcd5b89352c2d26fb
Reviewed-on: https://go-review.googlesource.com/c/go/+/206839
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

In the discussion of CL 171828 we decided that it was not necessary to
acquire timersLock around the call to moveTimers, because the world is
stopped. However, that is not correct, as sysmon runs even when the world
is stopped, and it calls timeSleepUntil which looks through the timers.
timeSleepUntil acquires timersLock, but that doesn't help if moveTimers
is running at the same time.

Updates #6239
Updates #27707
Updates #35462

Change-Id: I346c5bde594c4aff9955ae430b37c2b6fc71567f
Reviewed-on: https://go-review.googlesource.com/c/go/+/206938
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

Change-Id: I09090effcc5d814d4e024da3f944e825365588f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/205477
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Test fix: in dwarf_test.go don't try to run the TestDWARF testpoint on
windows with c-archive build mode (linker + debug/pe support for that
build mode on Windows is not fully baked it seems).

Fixes #35512.

Change-Id: I1c87ff3d62e5b98e75062b184d762fb5ed937745
Reviewed-on: https://go-review.googlesource.com/c/go/+/206899
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Our attempts to close existing open files are flaky. They will fail if,
for example, file descriptor 3 is open when the test binary starts.
Instead, report any such cases, and skip TestExtraFiles.

Updates #35469

Change-Id: I7caec083f3f4a31579bf28fc9c82ae89b1bde49a
Reviewed-on: https://go-review.googlesource.com/c/go/+/206939Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

change "fp" to "fd".

Change-Id: I00e5fafcb68891356d508c49aa89969bfed7ed10
GitHub-Last-Rev: b06f976a3bacc6fc6f1fd0e4fc8c50da9764f736
GitHub-Pull-Request: golang/go#35557
Reviewed-on: https://go-review.googlesource.com/c/go/+/207038Reviewed-by: Keith Randall <khr@golang.org>

In CL 206757 I added a log.Printf to identify when GOROOT is not read-only.
However, it interacts badly with test sharding in the builders:
the log is repeated for every shard.

Since the log statement isn't particularly high-value, just remove it.

Updates #30316

Change-Id: I385a7f35da59e38ad8b9beef92dc11af931d9571
Reviewed-on: https://go-review.googlesource.com/c/go/+/206898
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Not a fix, but will give us more info when it flakes again.

Updates #35113

Change-Id: I2f90c24530c1bea81dd9d8c7a59f4b0640dfa4c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/206819
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Provide initial linker support for riscv64.

Based on riscv-go port.

Updates #27532

Change-Id: I8a881ce41cd49efef0358bad9171d4d18aaf7ab2
Reviewed-on: https://go-review.googlesource.com/c/go/+/204624
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Change-Id: Icd5006e37861d892a5f3d4397c3826179c1b12ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/206657
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>

The problem should be fixed by the previous CL. Reenable async
preemption on darwin/arm64.

Updates #35439.

Change-Id: I93e8c4702b4d8fe6abaa6fc9c27def5c8aed1b59
Reviewed-on: https://go-review.googlesource.com/c/go/+/206419Reviewed-by: Keith Randall <khr@golang.org>

iOS does not support SA_ONSTACK. The signal handler runs on the
G stack. Any writes below the SP may be clobbered by the signal
handler (even without call injection). So we save LR after
decrementing SP on iOS.

Updates #35439.

Change-Id: Ia6d7a0669e0bcf417b44c031d2e26675c1184165
Reviewed-on: https://go-review.googlesource.com/c/go/+/206418
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I9596536e04aef034623b51b42f44e4978f07ac47
Reviewed-on: https://go-review.googlesource.com/c/go/+/204339
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Some, but not all, architectures mix in OS-provided random seeds when
initializing the fastrand state. The others have TODOs saying we need
to do the same. Lift that logic up in the architecture-independent
part, and use memhash to mix the seed instead of a simple addition.

Previously, dumping the fastrand state at initialization would yield
something like the following on linux-amd64, where the values in the
first column do not change between runs (as thread IDs are sequential
and always start at 0), and the values in the second column, while
changing every run, are pretty correlated:

first run:

0x0 0x44d82f1c
0x5f356495 0x44f339de
0xbe6ac92a 0x44f91cd8
0x1da02dbf 0x44fd91bc
0x7cd59254 0x44fee8a4
0xdc0af6e9 0x4547a1e0
0x3b405b7e 0x474c76fc
0x9a75c013 0x475309dc
0xf9ab24a8 0x4bffd075

second run:

0x0 0xa63fc3eb
0x5f356495 0xa6648dc2
0xbe6ac92a 0xa66c1c59
0x1da02dbf 0xa671bce8
0x7cd59254 0xa70e8287
0xdc0af6e9 0xa7129d2e
0x3b405b7e 0xa7379e2d
0x9a75c013 0xa7e4c64c
0xf9ab24a8 0xa7ecce07

With this change, we get initial states that appear to be much more
unpredictable, both within the same run as well as between runs:

0x11bddad7 0x97241c63
0x553dacc6 0x2bcd8523
0x62c01085 0x16413d92
0x6f40e9e6 0x7a138de6
0xa4898053 0x70d816f0
0x5ca5b433 0x188a395b
0x62778ca9 0xd462c3b5
0xd6e160e4 0xac9b4bd
0xb9571d65 0x597a981d

Change-Id: Ib22c530157d74200df0083f830e0408fd4aaea58
Reviewed-on: https://go-review.googlesource.com/c/go/+/203439
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

https://github.com/google/pprof/compare/54271f7e092f...27840fff0d09

Change-Id: I7ded9be6deaaf8d11bd8d228bca8d7eb3ada8774
Reviewed-on: https://go-review.googlesource.com/c/go/+/205780
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Updates #35518.

Change-Id: Icd052c8c68aae32696b5831a29e04cc4cb224b06
Reviewed-on: https://go-review.googlesource.com/c/go/+/206820
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This test was failing when GOROOT was read-only.

(I'm not sure why that was the case, but it's simpler to convert to to
a script than to try to debug the non-script test.)

Updates #28387

Change-Id: I9943e28d990e5d8b01da10e70531f3ab99e319a7
Reviewed-on: https://go-review.googlesource.com/c/go/+/206897
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I72de8cb5e1df7a73e46a4b7e5b4e7290fcca4bc1
Reviewed-on: https://go-review.googlesource.com/c/go/+/204162
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

EpollEvent needs padding before Fd as was already done for x/sys/unix in
CL 21971.

Fixes #35479

Change-Id: Iee963f9e26d0a23d16d6bab736fd71ae7f502894
Reviewed-on: https://go-review.googlesource.com/c/go/+/206838
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

There is a (theoretical, but possible) chance that the
random number values a, b used for TestDiv are 0 or 1,
in which case the test would fail.

This CL makes sure that a >= 1 and b >= 2 at all times.

Fixes #35523.

Change-Id: I6451feb94241249516a821cd0066e95a0c65b0ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/206818
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #29583

Change-Id: Ia89433bddd4c9f67ec1f0150b730cde8a7e973ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/206759
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This CL detects infinite loops due to negative dereference cycles
during escape analysis, and terminates the loop gracefully. We still
fail to print a complete explanation of the escape path, but esc.go
didn't print *any* explanation for these test cases, so the release
blocking issue here is simply that we don't infinite loop.

Updates #35518.

Change-Id: I39beed036e5a685706248852f1fa619af3b7abbc
Reviewed-on: https://go-review.googlesource.com/c/go/+/206619
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Also log a message and skip the Chmods if running as root.

Updates #30316

Change-Id: Ifb68d06ce845275a72d64c808407e8609df270bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/206757
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

At least on Darwin notewakeup is not async-signal-safe.

Fixes #35276

Change-Id: I1d7523715e8e77dbd7f21d9b1ed131e52d46cc41
Reviewed-on: https://go-review.googlesource.com/c/go/+/206078Reviewed-by: Austin Clements <austin@google.com>

If no writes to the package buffer happen, then the package clause
does not get printed. This is a bug for cases where a file just contains
the package clause.

We fix this by separating the printing of package clause to a new
function and calling it from (*pkgBuffer).Write as well as (*Package).flush.

Updates #31457

Change-Id: Ia3bd0ea3963274c460a45d1e37fafc6ee0a197f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/206128
Run-TryBot: Agniva De Sarker <agniva.quicksilver@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

The current division algorithm produces one word of result at a time,
using 2-word division to compute the top word and mulAddVWW to compute
the remainder. The top word may need to be adjusted by 1 or 2 units.

The recursive version, based on Burnikel, Ziegler, "Fast Recursive Division",
uses the same principles, but in a multi-word setting, so that
multiplication benefits from the Karatsuba algorithm (and possibly later
improvements).

benchmark                             old ns/op        new ns/op      delta
BenchmarkDiv/20/10-4                  38.2             38.3           +0.26%
BenchmarkDiv/40/20-4                  38.7             38.5           -0.52%
BenchmarkDiv/100/50-4                 62.5             62.6           +0.16%
BenchmarkDiv/200/100-4                238              259            +8.82%
BenchmarkDiv/400/200-4                311              338            +8.68%
BenchmarkDiv/1000/500-4               604              649            +7.45%
BenchmarkDiv/2000/1000-4              1214             1278           +5.27%
BenchmarkDiv/20000/10000-4            38279            36510          -4.62%
BenchmarkDiv/200000/100000-4          3022057          1359615        -55.01%
BenchmarkDiv/2000000/1000000-4        310827664        54012939       -82.62%
BenchmarkDiv/20000000/10000000-4      33272829421      1965401359     -94.09%
BenchmarkString/10/Base10-4           158              156            -1.27%
BenchmarkString/100/Base10-4          797              792            -0.63%
BenchmarkString/1000/Base10-4         3677             3814           +3.73%
BenchmarkString/10000/Base10-4        16633            17116          +2.90%
BenchmarkString/100000/Base10-4       5779029          1793808        -68.96%
BenchmarkString/1000000/Base10-4      889840820        85524031       -90.39%
BenchmarkString/10000000/Base10-4     134338236860     4935657026     -96.33%

Fixes #21960
Updates #30943

Change-Id: I134c6f81a47870c688ca95b6081eb9211def15a2
Reviewed-on: https://go-review.googlesource.com/c/go/+/172018Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

An error check was missing: If the first argument of a pipeline is
parenthesized, and the pipeline has further arguments, then
syntactically the pipeline is a function invocation and there must
be a "call". Tricky rare corner case, but easily caught.

Add the error check and some tests to verify behavior.

Fixes #31810.

Change-Id: Ica80b7c11284e4ea9e8cc94a01dbbc9a67e42079
Reviewed-on: https://go-review.googlesource.com/c/go/+/206124Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #30955

Change-Id: I8a2bff5215ddf6c3a80b1e760cb72b0bb9a5e0d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/206122Reviewed-by: Robert Griesemer <gri@golang.org>