We've copy-pasted the pattern of releasem in many places. This CL
replaces almost everywhere that manipulates g.m.locks and g.preempt
with calls to acquirem/releasem. There are a few where we do something
more complicated, like where exitsyscall has to restore the stack
bound differently depending on the preempt flag, which this CL leaves
alone.

Change-Id: Ia7a46c261daea6e7802b80e7eb9227499f460433
Reviewed-on: https://go-review.googlesource.com/c/go/+/170064
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

CL 3660 replaced m.gcing with m.preemptoff, but unintentionally
reversed the sense of part of a sanity check in notetsleep.
Originally, notetsleep required that it be called from g0 or with
preemption disabled (specifically from within the garbage collector).
CL 3660 made it require that it be called from g0 or that preemption
be *enabled*.

I'm not sure why it had the original exception for being called from a
user g within the garbage collector, but the current garbage collector
certainly doesn't need that, and the new condition is completely wrong.

Make the sanity check just require that it's called on g0.

Change-Id: I6980d44f5a4461935e10b1b33a981e32b1b7b0c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/170063
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Currently, every Pool is cleared completely at the start of each GC.
This is a problem for heavy users of Pool because it causes an
allocation spike immediately after Pools are clear, which impacts both
throughput and latency.

This CL fixes this by introducing a victim cache mechanism. Instead of
clearing Pools, the victim cache is dropped and the primary cache is
moved to the victim cache. As a result, in steady-state, there are
(roughly) no new allocations, but if Pool usage drops, objects will
still be collected within two GCs (as opposed to one).

This victim cache approach also improves Pool's impact on GC dynamics.
The current approach causes all objects in Pools to be short lived.
However, if an application is in steady state and is just going to
repopulate its Pools, then these objects impact the live heap size *as
if* they were long lived. Since Pooled objects count as short lived
when computing the GC trigger and goal, but act as long lived objects
in the live heap, this causes GC to trigger too frequently. If Pooled
objects are a non-trivial portion of an application's heap, this
increases the CPU overhead of GC. The victim cache lets Pooled objects
affect the GC trigger and goal as long-lived objects.

This has no impact on Get/Put performance, but substantially reduces
the impact to the Pool user when a GC happens. PoolExpensiveNew
demonstrates this in the substantially reduction in the rate at which
the "New" function is called.

name                 old time/op     new time/op     delta
Pool-12                 2.21ns ±36%     2.00ns ± 0%     ~     (p=0.070 n=19+16)
PoolOverflow-12          587ns ± 1%      583ns ± 1%   -0.77%  (p=0.000 n=18+18)
PoolSTW-12              5.57µs ± 3%     4.52µs ± 4%  -18.82%  (p=0.000 n=20+19)
PoolExpensiveNew-12     3.69ms ± 7%     1.25ms ± 5%  -66.25%  (p=0.000 n=20+19)

name                 old p50-ns/STW  new p50-ns/STW  delta
PoolSTW-12               5.48k ± 2%      4.53k ± 2%  -17.32%  (p=0.000 n=20+20)

name                 old p95-ns/STW  new p95-ns/STW  delta
PoolSTW-12               6.69k ± 4%      5.13k ± 3%  -23.31%  (p=0.000 n=19+18)

name                 old GCs/op      new GCs/op      delta
PoolExpensiveNew-12       0.39 ± 1%       0.32 ± 2%  -17.95%  (p=0.000 n=18+20)

name                 old New/op      new New/op      delta
PoolExpensiveNew-12       40.0 ± 6%       12.4 ± 6%  -68.91%  (p=0.000 n=20+19)

(https://perf.golang.org/search?q=upload:20190311.2)

Fixes #22950.

Change-Id: If2e183d948c650417283076aacc20739682cdd70
Reviewed-on: https://go-review.googlesource.com/c/go/+/166961
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Currently, Pool stores each per-P shard's overflow in a slice
protected by a Mutex. In order to store to the overflow or steal from
another shard, a P must lock that shard's Mutex. This allows for
simple synchronization between Put and Get, but has unfortunate
consequences for clearing pools.

Pools are cleared during STW sweep termination, and hence rely on
pinning a goroutine to its P to synchronize between Get/Put and
clearing. This makes the Get/Put fast path extremely fast because it
can rely on quiescence-style coordination, which doesn't even require
atomic writes, much less locking.

The catch is that a goroutine cannot acquire a Mutex while pinned to
its P (as this could deadlock). Hence, it must drop the pin on the
slow path. But this means the slow path is not synchronized with
clearing. As a result,

1) It's difficult to reason about races between clearing and the slow
path. Furthermore, this reasoning often depends on unspecified nuances
of where preemption points can occur.

2) Clearing must zero out the pointer to every object in every Pool to
prevent a concurrent slow path from causing all objects to be
retained. Since this happens during STW, this has an O(# objects in
Pools) effect on STW time.

3) We can't implement a victim cache without making clearing even
slower.

This CL solves these problems by replacing the locked overflow slice
with a lock-free structure. This allows Gets and Puts to be pinned the
whole time they're manipulating the shards slice (Pool.local), which
eliminates the races between Get/Put and clearing. This, in turn,
eliminates the need to zero all object pointers, reducing clearing to
O(# of Pools) during STW.

In addition to significantly reducing STW impact, this also happens to
speed up the Get/Put fast-path and the slow path. It somewhat
increases the cost of PoolExpensiveNew, but we'll fix that in the next
CL.

name                 old time/op     new time/op     delta
Pool-12                 3.00ns ± 0%     2.21ns ±36%  -26.32%  (p=0.000 n=18+19)
PoolOverflow-12          600ns ± 1%      587ns ± 1%   -2.21%  (p=0.000 n=16+18)
PoolSTW-12              71.0µs ± 2%      5.6µs ± 3%  -92.15%  (p=0.000 n=20+20)
PoolExpensiveNew-12     3.14ms ± 5%     3.69ms ± 7%  +17.67%  (p=0.000 n=19+20)

name                 old p50-ns/STW  new p50-ns/STW  delta
PoolSTW-12               70.7k ± 1%       5.5k ± 2%  -92.25%  (p=0.000 n=20+20)

name                 old p95-ns/STW  new p95-ns/STW  delta
PoolSTW-12               73.1k ± 2%       6.7k ± 4%  -90.86%  (p=0.000 n=18+19)

name                 old GCs/op      new GCs/op      delta
PoolExpensiveNew-12       0.38 ± 1%       0.39 ± 1%   +2.07%  (p=0.000 n=20+18)

name                 old New/op      new New/op      delta
PoolExpensiveNew-12       33.9 ± 6%       40.0 ± 6%  +17.97%  (p=0.000 n=19+20)

(https://perf.golang.org/search?q=upload:20190311.1)

Fixes #22331.
For #22950.

Change-Id: Ic5cd826e25e218f3f8256dbc4d22835c1fecb391
Reviewed-on: https://go-review.googlesource.com/c/go/+/166960
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

This adds two benchmarks that will highlight two problems in Pool that
we're about to address.

The first benchmark measures the impact of large Pools on GC STW time.
Currently, STW time is O(# of items in Pools), and this benchmark
demonstrates 70µs STW times.

The second benchmark measures the impact of fully clearing all Pools
on each GC. Typically this is a problem in heavily-loaded systems
because it causes a spike in allocation. This benchmark stresses this
by simulating an expensive "New" function, so the cost of creating new
objects is reflected in the ns/op of the benchmark.

For #22950, #22331.

Change-Id: I0c8853190d23144026fa11837b6bf42adc461722
Reviewed-on: https://go-review.googlesource.com/c/go/+/166959
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

This adds a dynamically sized, lock-free, single-producer,
multi-consumer queue that will be used in the new Pool stealing
implementation. It's built on top of the fixed-size queue added in the
previous CL.

For #22950, #22331.

Change-Id: Ifc0ca3895bec7e7f9289ba9fb7dd0332bf96ba5a
Reviewed-on: https://go-review.googlesource.com/c/go/+/166958
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

This is the first step toward fixing multiple issues with sync.Pool.
This adds a fixed size, lock-free, single-producer, multi-consumer
queue that will be used in the new Pool stealing implementation.

For #22950, #22331.

Change-Id: I50e85e3cb83a2ee71f611ada88e7f55996504bb5
Reviewed-on: https://go-review.googlesource.com/c/go/+/166957
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Change-Id: Iec5e69b3ea163f42234d3b73696427a7aa8732e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/170884Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I990c451ff24844b39dee2477cec4caa9db2e8ebb
Reviewed-on: https://go-review.googlesource.com/c/go/+/170883Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This matches NullBool, NullFloat64, and NullInt64.

Fixes #30305

Change-Id: I79bfcf04a3d43b965d2a3159b0ac22f3e8084a53
Reviewed-on: https://go-review.googlesource.com/c/go/+/170699
Run-TryBot: Daniel Theophanes <kardianos@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

fdopendir takes ownership of its file descriptor argument.
Getdirentries shouldn't do that, so dup the file descriptor
before passing to fdopendir.

Fixes #31269

Change-Id: Ie36be8fd6c59eb339dcc9f40228d4191fc1e5850
Reviewed-on: https://go-review.googlesource.com/c/go/+/170698
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Don't panic with "index out of range" on empty string argument.

Fixes golang/go#31277

Change-Id: I005f9523caec76337cb2ec87272a6be4736bce18
Reviewed-on: https://go-review.googlesource.com/c/go/+/170937
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I8a40461b93eab034ed930e0c5e32391f84cdbc5a
Reviewed-on: https://go-review.googlesource.com/c/go/+/170799Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Sebastien Binet <seb.binet@gmail.com>

Upon unrecovered panic and program termination, process exit code is hard-coded
to 2, not set to the parameter passed to panic().

Change-Id: If64b75493227b4fd69c0bbb529f84e6df2d1b93f
Reviewed-on: https://go-review.googlesource.com/c/go/+/167709Reviewed-by: Robert Griesemer <gri@golang.org>

load.PackageAndErrors now preloads data used to build load.Package
structures. Multiple packages may be preloaded in parallel, so this
parallelizes most of the package loading work.

The actual package construction and error-checking process is still
sequential, since this process needs to detect and report cycles.

Fixes #29758

Change-Id: Icf37e6669836ce8aad076e34fd895f97f4f3f9e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/161397
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

If x does not have an inverse modulo m, and a negative exponent is used,
return nil just like ModInverse does now.

Change-Id: I8fa72f7a851e8cf77c5fab529ede88408740626f
Reviewed-on: https://go-review.googlesource.com/c/go/+/170757
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

The INODE64 variant only exists on 64-bit.

Fixes #31262

Change-Id: I528277c9b3312fdb15463ccbea0d537ff300f4ae
Reviewed-on: https://go-review.googlesource.com/c/go/+/170837
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This adds an internal runtime debug log. It uses per-M time-stamped
ring buffers of binary log records. On panic, these buffers are
collected, interleaved, and printed.

The entry-point to the debug log is a new "dlog" function. dlog is
designed so it can be used even from very constrained corners of the
runtime such as signal handlers or inside the write barrier.

The facility is only enabled if the debuglog build tag is set.
Otherwise, it compiles away to a no-op implementation.

The debug log format is also designed so it would be reasonable to
decode from a core dump, though this hasn't been implemented.

Change-Id: I6e2737c286358e97a0d8091826498070b95b66a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/157997
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

This change adds directives to link the res_search function in libSystem.
The corresponding Go function is then used in `lookup_darwin.go` for
resolution when cgo is disabled. This makes DNS resolution logic more
reliable as macOS has some unique quirks such as the `/etc/resolver/`
directory for specifying nameservers.

Fixes #12524

Change-Id: I367263c4951383965b3ef6491196152f78e614b1
GitHub-Last-Rev: 3c3ff6bfa7e4811f206f3b119a867c841a016e10
GitHub-Pull-Request: golang/go#30686
Reviewed-on: https://go-review.googlesource.com/c/go/+/166297
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

When building as part of the bootstrap process, avoid
use of "go:linkname" applied to variables, since this
feature is ill-defined/unsupported for gccgo.

Updates #30771.

Change-Id: Id44d01b5c98d292702e5075674117518cb59e2d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/170737Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This change adds the GOWASM option "satconv" to enable the generation
of experimental saturating (non-trapping) float-to-int conversions.
It improves the performance of the conversion by 42%.

Previously the conversions had already been augmented with helper
functions to have saturating behavior. Now Wasm.rules is always using
the new operation names and wasm/ssa.go is falling back to the helpers
if the feature is not enabled.

The feature is in phase 4 of the WebAssembly proposal process:
https://github.com/WebAssembly/meetings/blob/master/process/phases.md

More information on the feature can be found at:
https://github.com/WebAssembly/nontrapping-float-to-int-conversions/blob/master/proposals/nontrapping-float-to-int-conversion/Overview.md

Change-Id: Ic6c3688017054ede804b02b6b0ffd4a02ef33ad7
Reviewed-on: https://go-review.googlesource.com/c/go/+/170119Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This commit adds a KeepAlive field to ListenConfig and uses it
analogously to Dialer.KeepAlive to set TCP KeepAlives per default on
Accept()

Fixes #23378

Change-Id: I57eaf9508c979e7f0e2b8c5dd8e8901f6eb27fd6
GitHub-Last-Rev: e9e035d53ee8aa3d899d12db08b293f599daecb6
GitHub-Pull-Request: golang/go#31242
Reviewed-on: https://go-review.googlesource.com/c/go/+/170678
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Rewrote a few lines to be more idiomatic/less assembly-ish.

Benchmarked with `go test -bench Float -tags math_big_pure_go`:

name                  old time/op    new time/op    delta
FloatString/100-8        751ns ± 0%     746ns ± 1%  -0.71%  (p=0.000 n=10+10)
FloatString/1000-8      22.9µs ± 0%    22.9µs ± 0%    ~     (p=0.271 n=10+10)
FloatString/10000-8     1.89ms ± 0%    1.89ms ± 0%    ~     (p=0.481 n=10+10)
FloatString/100000-8     184ms ± 0%     184ms ± 0%    ~     (p=0.094 n=9+9)
FloatAdd/10-8           56.4ns ± 1%    56.5ns ± 0%    ~     (p=0.170 n=9+9)
FloatAdd/100-8          59.7ns ± 0%    59.3ns ± 0%  -0.70%  (p=0.000 n=8+9)
FloatAdd/1000-8          101ns ± 0%      99ns ± 0%  -1.89%  (p=0.000 n=8+8)
FloatAdd/10000-8         553ns ± 0%     536ns ± 0%  -3.00%  (p=0.000 n=9+10)
FloatAdd/100000-8       4.94µs ± 0%    4.74µs ± 0%  -3.94%  (p=0.000 n=9+10)
FloatSub/10-8           50.3ns ± 0%    50.5ns ± 0%  +0.52%  (p=0.000 n=8+8)
FloatSub/100-8          52.0ns ± 0%    52.2ns ± 1%  +0.46%  (p=0.012 n=8+10)
FloatSub/1000-8         77.9ns ± 0%    77.3ns ± 0%  -0.80%  (p=0.000 n=7+8)
FloatSub/10000-8         371ns ± 0%     362ns ± 0%  -2.67%  (p=0.000 n=10+10)
FloatSub/100000-8       3.20µs ± 0%    3.10µs ± 0%  -3.16%  (p=0.000 n=10+10)
ParseFloatSmallExp-8    7.84µs ± 0%    7.82µs ± 0%  -0.17%  (p=0.037 n=9+9)
ParseFloatLargeExp-8    29.3µs ± 1%    29.5µs ± 0%    ~     (p=0.059 n=9+8)
FloatSqrt/64-8           516ns ± 0%     519ns ± 0%  +0.54%  (p=0.000 n=9+9)
FloatSqrt/128-8         1.07µs ± 0%    1.07µs ± 0%    ~     (p=0.109 n=8+9)
FloatSqrt/256-8         1.23µs ± 0%    1.23µs ± 0%  +0.50%  (p=0.000 n=9+9)
FloatSqrt/1000-8        3.43µs ± 0%    3.44µs ± 0%  +0.53%  (p=0.000 n=9+8)
FloatSqrt/10000-8       40.9µs ± 0%    40.7µs ± 0%  -0.39%  (p=0.000 n=9+8)
FloatSqrt/100000-8      1.07ms ± 0%    1.07ms ± 0%  -0.10%  (p=0.017 n=10+9)
FloatSqrt/1000000-8     89.3ms ± 0%    89.2ms ± 0%  -0.07%  (p=0.015 n=9+8)

Change-Id: Ibf07c6142719d11bc7f329246957d87a9f3ba3d2
GitHub-Last-Rev: 870a041ab7bb9c24be083114f53653a5f4eed611
GitHub-Pull-Request: golang/go#31220
Reviewed-on: https://go-review.googlesource.com/c/go/+/170449
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Before this fix, a mistaken := in a (const/type/var) declaration
ended that declaration with an error from which the parser didn't
recover well. This low-cost change will provide a better error
message and lets the parser recover perfectly.

Fixes #31092.

Change-Id: Ic4f94dc5e29dd00b7ef6d53a80dded638e3cea80
Reviewed-on: https://go-review.googlesource.com/c/go/+/169958Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Getdirentries is implemented with the __getdirentries64 function
in libSystem.dylib. That function works, but it's on Apple's
can't-be-used-in-an-app-store-application list.

Implement Getdirentries using the underlying fdopendir/readdir_r/closedir.
The simulation isn't faithful, and could be slow, but it should handle
common cases.

Don't use Getdirentries in the stdlib, use fdopendir/readdir_r/closedir
instead (via (*os.File).readdirnames).

Fixes #30933

Update #28984

RELNOTE=yes

Change-Id: Ia6b5d003e5bfe43ba54b1e1d9cfa792cc6511717
Reviewed-on: https://go-review.googlesource.com/c/go/+/168479Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

These new calls should not prevent NOSPLIT promotion, like the old ones.
These new calls should not prevent racefuncenter/exit removal.

(The latter was already true, as the new calls are not yet lowered
to StaticCalls at the point where racefuncenter/exit removal is done.)

Add tests to make sure we don't regress (again).

Fixes #31219

Change-Id: I3fb6b17cdd32c425829f1e2498defa813a5a9ace
Reviewed-on: https://go-review.googlesource.com/c/go/+/170639
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>

Some var declarations return "extra expression" or "missing expression"
errors when they should return “assignment mismatch” instead. Change
the returned error messages to exhibit the desired behavior.

Fixes #30085.

Change-Id: I7189355fbb0f976d70100779db4f81a9ae64fb11
Reviewed-on: https://go-review.googlesource.com/c/go/+/161558Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>

We rely on SSL certificates to verify the identity of origin servers.
If an HTTPS server redirects through a plain-HTTP URL, that hop can be
compromised. We should allow it only if the user set the -insecure
flag explicitly.

Fixes #29591

Change-Id: I00639541cca2ca034c01c464385a43b3aa8ee84f
Reviewed-on: https://go-review.googlesource.com/c/go/+/156838
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

nanomsg.org currently performs an HTTPS-to-HTTP redirect, so this case
fails after the fix for #29591.

Updates #29591

Change-Id: I6306d378ef213e98c0271258bbc6669bb33f9021
Reviewed-on: https://go-review.googlesource.com/c/go/+/170637
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Fixes #31233

Change-Id: I2831d5e6532d3f4ed7eb99af5d6e0e1a41ebac9a
Reviewed-on: https://go-review.googlesource.com/c/go/+/170624Reviewed-by: Andrew Bonventre <andybons@golang.org>

Fixes #30688

Change-Id: I8b63feba4b18bc07a09f6fbfaa33c1b3326b40e6
Reviewed-on: https://go-review.googlesource.com/c/go/+/169597Reviewed-by: Rob Pike <r@golang.org>

Change-Id: I32b0c02039d8baca1358dac2cc0afd14fa6cd173
GitHub-Last-Rev: d3be7aa039fbe94450c54f2c1dc5a510cf183378
GitHub-Pull-Request: golang/go#31232
Reviewed-on: https://go-review.googlesource.com/c/go/+/170657Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

mvs.BuildList and functions that invoke it directly (UpgradeAll) now
return an *mvs.BuildListError when there is an error retrieving the
requirements for a module. This new error prints the chain of
requirements from the main module to the module where the error
occurred.

These errors come up most commonly when a go.mod file has an
unexpected module path or can't be parsed for some other reason. It's
currently difficult to debug these errors because it's not clear where
the "bad" module is required from. Tools like "go list -m" and
"go mod why" don't work without the build graph.

Fixes #30661

Change-Id: I3c9d4683dcd9a5d7c259e5e4cc7e1ee209700b10
Reviewed-on: https://go-review.googlesource.com/c/go/+/166984
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

The compiler (and race detector) don't interpret locking a file as a
synchronization operation, so we add an explicit (and redundant)
sync.Mutex to make that property clear.

The additional synchronization makes it safe to parallelize the tests
in cmd/go/internal/modfetch/coderepo_test.go, which cuts the wall time
of that test by around 50%.

Updates #30550

Change-Id: Ief3479020ebf9e0fee524a4aae5568697727c683
Reviewed-on: https://go-review.googlesource.com/c/go/+/170597
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Jay Conrod <jayconrod@google.com>

As ld on AIX doesn't keep the same layout in .text section,
-Wl,-bnoobjreoder must be passed to gcc when building a C program with a
Go archive.

Change-Id: I89b584cce43ab5792f315192b073923c10d5690e
Reviewed-on: https://go-review.googlesource.com/c/go/+/170538
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Decoder.Decode and Unmarshal actually scan the input bytes twice - the
first time to check for syntax errors and the length of the value, and
the second to perform the decoding.

It's in the second scan that we actually tokenize the bytes. Since
syntax errors aren't a possibility, we can take shortcuts.

In particular, literals such as quoted strings are very common in JSON,
so we can avoid a lot of work by special casing them.

name                  old time/op    new time/op    delta
CodeDecoder-8           10.3ms ± 1%     9.1ms ± 0%  -11.89%  (p=0.002 n=6+6)
UnicodeDecoder-8         342ns ± 0%     283ns ± 0%  -17.25%  (p=0.000 n=6+5)
DecoderStream-8          239ns ± 0%     230ns ± 0%   -3.90%  (p=0.000 n=6+5)
CodeUnmarshal-8         11.0ms ± 0%     9.8ms ± 0%  -11.45%  (p=0.002 n=6+6)
CodeUnmarshalReuse-8    10.3ms ± 0%     9.0ms ± 0%  -12.72%  (p=0.004 n=5+6)
UnmarshalString-8        104ns ± 0%      92ns ± 0%  -11.35%  (p=0.002 n=6+6)
UnmarshalFloat64-8      93.2ns ± 0%    87.6ns ± 0%   -6.01%  (p=0.010 n=6+4)
UnmarshalInt64-8        74.5ns ± 0%    71.5ns ± 0%   -3.91%  (p=0.000 n=5+6)

name                  old speed      new speed      delta
CodeDecoder-8          189MB/s ± 1%   214MB/s ± 0%  +13.50%  (p=0.002 n=6+6)
UnicodeDecoder-8      40.9MB/s ± 0%  49.5MB/s ± 0%  +20.96%  (p=0.002 n=6+6)
CodeUnmarshal-8        176MB/s ± 0%   199MB/s ± 0%  +12.93%  (p=0.002 n=6+6)

Updates #28923.

Change-Id: I7a5e2aef51bd4ddf2004aad24210f6f50e01eaeb
Reviewed-on: https://go-review.googlesource.com/c/go/+/151042
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #23109.

Change-Id: I55f7860c868acc948a6397ab6a9295e177724a56
Reviewed-on: https://go-review.googlesource.com/c/go/+/170450
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

(*mvsReqs).Required assumes that it is safe to mutate the slice
returned by (*mvsReqs).required. In most cases, that was true, but in
the case of -mod=vendor it resulted in unsynchronized (and
potentially interfering) writes to the global vendorList.

Fixes #30550

Change-Id: I99bcc2037e0182418b7dfda1002f8b540dbf3a1d
Reviewed-on: https://go-review.googlesource.com/c/go/+/170598
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

splittests already contains most of the tests that cover explode. Add
the missing ones and skip the append test for empty results which would
otherwise lead to an "index out of range" panic.

Change-Id: I2cb922282d2676be9ef85f186513075ae17c0243
Reviewed-on: https://go-review.googlesource.com/c/go/+/170126
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 sendmsg, recvmsg to use nsendmsg, nrecvmsg on AIX.
These syscalls support the new msghdr structure (with Control
and Controllen) which is needed for golang.org/x/net.
Also define SockaddrDataLink.

Change-Id: I233fbd24f9eb86648e0d4d50c2b56da3626292d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/170537
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>