TestPreemptM doesn't test preemptM, it tests signalM. Rename it and
co-locate it with the other tests related to signals.

Change-Id: I7b95f2ba96530c49cfa8d5bf33282946b5f2d9af
Reviewed-on: https://go-review.googlesource.com/c/go/+/203891
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

TestPreemptM tests signal delivery using SIGUSR1, but (for unknown
reasons) SIGUSR1 is blocked by default on android/arm and
android/arm64, causing the test to fail.

This fixes the test by ensuring that SIGUSR1 is unblocked for this
test.

Updates #10958, #24543.

Change-Id: I9f81fbab53f96c74622aabcb6f5276f79e2b6d33
Reviewed-on: https://go-review.googlesource.com/c/go/+/203957
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

As suggested by comments from the review of CL 168478, this adds
Go code to do reverse bytes and removes the asm code, as well
as making a few cosmetic changes.

Change-Id: I08276a11222e03c3b42f4c9dc0d10a371a418be7
Reviewed-on: https://go-review.googlesource.com/c/go/+/203937
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>

Mostly replaced [:x] slice operation with [:x:x]. 

According to @mdempsky, compiler specially recognizes when you combine
a pointer conversion with a full slice operation in a single expression
and makes an exception.

Updates golang/go#34972

Change-Id: I07d9de3b31da254d55f50d14c18155f8fc8f3ece
Reviewed-on: https://go-review.googlesource.com/c/go/+/203442Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>

n.Opt() is used in walkCheckPtrArithmetic to prevent infinite loops. The
fact that it's used today because n.Opt() is not used for OCONVNOP
during walk.go. If that changes, then it's not safe to repalce it
anymore. So doing hard fail if that case happens, the author of new
changes will be noticed and must change the usage of n.Opt() inside
walkCheckPtrArithmetic, too.

Change-Id: Ic7094baa1759c647fc10e82457c19026099a0d47
Reviewed-on: https://go-review.googlesource.com/c/go/+/202497
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Windows uses '\' not '/'.

Fixes #35175.

Change-Id: Ib3d01dcf148fc0675496d5213f5bcc9cf210a6fc
Reviewed-on: https://go-review.googlesource.com/c/go/+/203889Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

The asm encoder generally assumes that the lowest 5 bits of the
REG_XX constants match the machine instruction encoding, i.e.
the lowest 5 bits is the register number. This was not true for
FCR registers and M registers. Make it so.

MOV Rx, FCRy was encoded as two machine instructions. The first
is unnecessary. Remove.

Change-Id: Ib988e6b109ba8f564337cdd31019c1a6f1881f5b
Reviewed-on: https://go-review.googlesource.com/c/go/+/203717
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

For #10958, #24543, but makes sense on its own.

Change-Id: I2a87dab66b82a1863e4b6512b1f8def51463ce2a
Reviewed-on: https://go-review.googlesource.com/c/go/+/203284
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

We already have Load8, And8, and Or8.

For #10958, #24543, but makes sense on its own.

Change-Id: I478529fc643edc57efdeccaae413c99edd19b2eb
Reviewed-on: https://go-review.googlesource.com/c/go/+/203283
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Change-Id: Idac8473d1752059bf2f617fd7a781000ee2c3af4
GitHub-Last-Rev: 02a3aa1a3241d3ed4422518f1c954cd54bbe858e
GitHub-Pull-Request: golang/go#35141
Reviewed-on: https://go-review.googlesource.com/c/go/+/203218
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

"declared and not used" is technically correct, but might confuse
the user. Switching "and" to "but" will hopefully create the
contrast for the users: they did one thing (declaration), but
not the other --- actually using the variable.

This new message is still not ideal (specifically, declared is not
entirely precise here), but at least it matches the other parsers
and is one step in the right direction.

Change-Id: I725c7c663535f9ab9725c4b0bf35b4fa74b0eb20
Reviewed-on: https://go-review.googlesource.com/c/go/+/203282
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

This is a 2nd attempt at fixing CL 162337 which had an off-by-one error.
We were unconditionally getting the position of the start of the next line
from the last import without checking whether it is the end of the file or not.

Fix the code to check for that and move the testcase added in CL 190523
to the end of the file for it to trigger the issue properly.

Fixes #18929

Change-Id: I59e77256e256570b160fea6a17bce9ef49e810df
Reviewed-on: https://go-review.googlesource.com/c/go/+/190480
Run-TryBot: Agniva De Sarker <agniva.quicksilver@gmail.com>
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Reviewed-by: Robert Griesemer <gri@golang.org>

Allows Go asm calls referencing a function in a .syso file to be
passed through to the external linker, that would have otherwise
raised a "relocation target X not defined" error in cmd/link.

Fixes #33139

Change-Id: I2a8eb6063ebcd05fac96f141acf7652cf9189766
Reviewed-on: https://go-review.googlesource.com/c/go/+/198798
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Remove skipping of TestRemoveUnreadableDir on Windows.

Fixes #26295

Change-Id: I364a3caa55406c855ece807759f6298f7e4ddf1e
Reviewed-on: https://go-review.googlesource.com/c/go/+/203599
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

In the second step of make.bash, cmd/dist builds cmd/go by invoking
the compiler, linker, and other tools directly on transitive
dependencies of cmd/go. Essentially, cmd/dist acts as a minimal
version of 'go install' when building go_toolchain.

Until now, cmd/go has had no transitive dependencies in vendor
directories. This changes in CL 202698, where several packages are
deleted and equivalent versions in golang.org/x/mod are used
instead. So this CL adds support to cmd/dist for vendor directories.

Updates #31761

Change-Id: Iab4cdc7e505069a8df296287d16fbaa871944955
Reviewed-on: https://go-review.googlesource.com/c/go/+/203537
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Correctly track whether the closing } of a block (or a function body)
is present or not in the AST and report correct End() positions in
each case.

There are more cases like this but this CL addresses an immediate
issue and sets a precedent for how to fix similar cases if a need
arises.

Fixes #33649.

Change-Id: Id6662ddaac09f3c15f8003edc9275fe2b0c41c78
Reviewed-on: https://go-review.googlesource.com/c/go/+/202581
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

The go.mod sum was present, but not the module sum.

Change-Id: I7def303bf4507a88dfa1bb0502116efde4d64b01
Reviewed-on: https://go-review.googlesource.com/c/go/+/203882
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I243b6521cb91ba5312c0857ca81cf422a7c7b21a
Reviewed-on: https://go-review.googlesource.com/c/go/+/203881
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

We use -1 for Phi argLength, not "a really large number".

Change-Id: I5d4fa364c22c3cf40213f2368a9a20de7e989aac
Reviewed-on: https://go-review.googlesource.com/c/go/+/203883
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

pname already translated package path into a file path on for statement.
Use same as filepath.Clean rather than path.Clean.

Change-Id: I9782e2396313abc39ac55e3fdcec8f53bcaff84e
Reviewed-on: https://go-review.googlesource.com/c/go/+/202377Reviewed-by: Matthew Dempsky <mdempsky@google.com>

They all seem pretty low-risk, and the overall diff is small.

While at it, remove one in go/build too.

Change-Id: I31df52c1c97d843b06f6c1dc63462d390db4470d
Reviewed-on: https://go-review.googlesource.com/c/go/+/203607
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

On illumos systems, check for the "zone.cpu-cap" resource control when
determining how many usable CPUs are available.  If the resource control
is not set, or we are unable to read it, ignore the failure and return
the value we used to return; i.e., the CPU count from
sysconf(_SC_NPROCESSORS_ONLN).

Fixes golang/go#35199

Change-Id: Ic8a408f84cd140d544d128f1281baad527fb5e35
Reviewed-on: https://go-review.googlesource.com/c/go/+/203758
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

ZeroAuto was used with the ambiguously live logic. The
ambiguously live logic is removed as we switched to stack
objects. It is now never called. Remove.

Change-Id: If4cdd7fed5297f8ab591cc392a76c80f57820856
Reviewed-on: https://go-review.googlesource.com/c/go/+/203538
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #34751

Change-Id: I5ae1bb2bfddaa05245b364556d2b999b158a4cc4
Reviewed-on: https://go-review.googlesource.com/c/go/+/203879Reviewed-by: Bryan C. Mills <bcmills@google.com>

First letter of an error string should not be capitalized, as prescribed in the [wiki](https://github.com/golang/go/wiki/Errors).

Change-Id: Iea1413f19b5240d3bef79f216094d210b54bdb62
GitHub-Last-Rev: d8e167107122b603c4f647d722537668ad1c680d
GitHub-Pull-Request: golang/go#35203
Reviewed-on: https://go-review.googlesource.com/c/go/+/203797Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

If a compilation has multiple text sections, code in
textOff must compare the offset argument against the range
for each text section to determine which one it is in.
The comparison looks like this:

if uintptr(off) >= sectaddr && uintptr(off) <= sectaddr+sectlen

If the off value being compared is equal to sectaddr+sectlen then it
is not within the range of the text section but after it. The
comparison should be just '<'.

Updates #35207

Change-Id: I114633fd734563d38f4e842dd884c6c239f73c95
Reviewed-on: https://go-review.googlesource.com/c/go/+/203817
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

This adds an asm implementation of the p256 functions used
in crypto/elliptic, utilizing VMX, VSX to improve performance.
On a power9 the improvement is:

elliptic benchmarks:
name            old time/op    new time/op    delta
BaseMult          1.40ms ± 0%    1.44ms ± 0%   +2.66%  (p=0.029 n=4+4)
BaseMultP256       317µs ± 0%      50µs ± 0%  -84.14%  (p=0.029 n=4+4)
ScalarMultP256     854µs ± 2%     214µs ± 0%  -74.91%  (p=0.029 n=4+4)

ecdsa benchmarks:
name           old time/op    new time/op    delta
SignP256          377µs ± 0%     111µs ± 0%  -70.57%  (p=0.029 n=4+4)
SignP384         6.55ms ± 0%    6.48ms ± 0%   -1.03%  (p=0.029 n=4+4)
VerifyP256       1.19ms ± 0%    0.26ms ± 0%  -78.54%  (p=0.029 n=4+4)
KeyGeneration     319µs ± 0%      52µs ± 0%  -83.56%  (p=0.029 n=4+4)

This implemenation is based on the s390x implementation, using
comparable instructions for most with some minor changes where the
instructions are not quite the same.

Some changes were also needed since s390x is big endian and ppc64le
is little endian.

This also enables the fuzz_test for ppc64le.

Change-Id: I59a69515703b82ad2929f68ba2f11208fa833181
Reviewed-on: https://go-review.googlesource.com/c/go/+/168478
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>

If we marshal a non-pointer struct field whose type implements Marshaler with
a non-pointer receiver, then we avoid an allocation if we take the address of
the field before casting it to an interface.

name               old time/op    new time/op    delta
EncodeMarshaler-8     104ns ± 1%      92ns ± 2%  -11.72%  (p=0.001 n=7+7)

name               old alloc/op   new alloc/op   delta
EncodeMarshaler-8     36.0B ± 0%      4.0B ± 0%  -88.89%  (p=0.000 n=8+8)

name               old allocs/op  new allocs/op  delta
EncodeMarshaler-8      2.00 ± 0%      1.00 ± 0%  -50.00%  (p=0.000 n=8+8)

Test coverage already looks good enough for this change. TestRefValMarshal
already covers all possible combinations of value & pointer receivers on
value and pointer struct fields.

Change-Id: I6fc7f72396396d98f9a90c3c86e813690f41c099
Reviewed-on: https://go-review.googlesource.com/c/go/+/203608Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Based on work by Mikaël Urankar (@MikaelUrankar).

Updates #24715
Updates #35197

Change-Id: I91144101043d67d3f8444bf8389c9606abe2a66c
Reviewed-on: https://go-review.googlesource.com/c/go/+/199919
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Updates golang/go#35197

Change-Id: I4fd85c84475761d71d2c17e62796e0a411cf91d8
Reviewed-on: https://go-review.googlesource.com/c/go/+/203519
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

_defer.fn can be nil, so we need to add a check when dumping
_defer.fn.fn.

Fixes #35172

Change-Id: Ic1138be5ec9dce915a87467cfa51ff83acc6e3a9
Reviewed-on: https://go-review.googlesource.com/c/go/+/203697
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

This change improves performance of Compact by using a sync.Pool to allow re-use
of a scanner. This also has the side-effect of removing an allocation for each
field that implements Marshaler when marshalling JSON.

name               old time/op    new time/op    delta
EncodeMarshaler-8     118ns ± 2%     104ns ± 1%  -12.21%  (p=0.001 n=7+7)

name               old alloc/op   new alloc/op   delta
EncodeMarshaler-8      100B ± 0%       36B ± 0%  -64.00%  (p=0.000 n=8+8)

name               old allocs/op  new allocs/op  delta
EncodeMarshaler-8      3.00 ± 0%      2.00 ± 0%  -33.33%  (p=0.000 n=8+8)

Change-Id: Ic70c61a0a6354823da5220f5aad04b94c054f233
Reviewed-on: https://go-review.googlesource.com/c/go/+/200864Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

There's no reason not to enable DEP in 2019, especially given Go's
minimum operating system level.

RELNOTE=yes

Change-Id: I9c3bbc5b05a1654876a218123dd57b9c9077b780
Reviewed-on: https://go-review.googlesource.com/c/go/+/203601Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

This test's existence was predicated upon assumptions about the full
range of known data types and known data into those types. However,
we've learned from Microsoft that there are several undocumented secret
registry types that are in use by various parts of Windows, and we've
learned from inspection that many Microsoft uses of registry types don't
strictly adhere to the recommended value size. It's therefore foolhardy
to make any assumptions about what goes in and out of the registry, and
so this test, as well as its "blacklist", are meaningless.

Fixes #35084

Change-Id: I6c3fe5fb0e740e88858321b3b042c0ff1a23284e
Reviewed-on: https://go-review.googlesource.com/c/go/+/203604
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

Rhys Hiltner noted in #14939 that this defer was
syntactically inside a loop, but was only ever

executed once. Now that defer in a loop
is significantly slower, pull this one out.

name                                    old time/op   new time/op   delta
Throughput/MaxPacket/1MB/TLSv12-8        3.94ms ± 8%   3.93ms ±13%    ~     (p=0.967 n=15+15)
Throughput/MaxPacket/1MB/TLSv13-8        4.33ms ± 3%   4.51ms ± 7%  +4.00%  (p=0.000 n=14+14)
Throughput/MaxPacket/2MB/TLSv12-8        6.80ms ± 6%   7.01ms ± 4%  +3.15%  (p=0.000 n=14+14)
Throughput/MaxPacket/2MB/TLSv13-8        6.96ms ± 5%   6.80ms ± 5%  -2.43%  (p=0.006 n=15+14)
Throughput/MaxPacket/4MB/TLSv12-8        12.0ms ± 3%   11.7ms ± 2%  -2.88%  (p=0.000 n=15+13)
Throughput/MaxPacket/4MB/TLSv13-8        12.1ms ± 3%   11.7ms ± 2%  -3.54%  (p=0.000 n=13+13)
Throughput/MaxPacket/8MB/TLSv12-8        22.2ms ± 3%   21.6ms ± 3%  -2.97%  (p=0.000 n=15+15)
Throughput/MaxPacket/8MB/TLSv13-8        22.5ms ± 5%   22.0ms ± 3%  -2.34%  (p=0.004 n=15+15)
Throughput/MaxPacket/16MB/TLSv12-8       42.4ms ± 3%   41.3ms ± 3%  -2.49%  (p=0.001 n=15+15)
Throughput/MaxPacket/16MB/TLSv13-8       43.4ms ± 5%   42.3ms ± 3%  -2.33%  (p=0.006 n=15+14)
Throughput/MaxPacket/32MB/TLSv12-8       83.1ms ± 4%   80.6ms ± 3%  -2.98%  (p=0.000 n=15+15)
Throughput/MaxPacket/32MB/TLSv13-8       85.2ms ± 8%   82.6ms ± 4%  -3.02%  (p=0.005 n=15+15)
Throughput/MaxPacket/64MB/TLSv12-8        167ms ± 7%    158ms ± 2%  -5.21%  (p=0.000 n=15+15)
Throughput/MaxPacket/64MB/TLSv13-8        170ms ± 4%    162ms ± 3%  -4.83%  (p=0.000 n=15+15)
Throughput/DynamicPacket/1MB/TLSv12-8    4.13ms ± 7%   4.00ms ± 8%    ~     (p=0.061 n=15+15)
Throughput/DynamicPacket/1MB/TLSv13-8    4.72ms ± 6%   4.64ms ± 7%    ~     (p=0.377 n=14+15)
Throughput/DynamicPacket/2MB/TLSv12-8    7.29ms ± 7%   7.09ms ± 7%    ~     (p=0.070 n=15+14)
Throughput/DynamicPacket/2MB/TLSv13-8    7.18ms ± 5%   6.59ms ± 4%  -8.34%  (p=0.000 n=15+15)
Throughput/DynamicPacket/4MB/TLSv12-8    12.3ms ± 3%   11.9ms ± 4%  -3.31%  (p=0.000 n=15+14)
Throughput/DynamicPacket/4MB/TLSv13-8    12.2ms ± 4%   12.0ms ± 4%  -1.91%  (p=0.019 n=15+15)
Throughput/DynamicPacket/8MB/TLSv12-8    22.4ms ± 3%   21.9ms ± 3%  -2.18%  (p=0.000 n=15+15)
Throughput/DynamicPacket/8MB/TLSv13-8    22.7ms ± 3%   22.2ms ± 3%  -2.35%  (p=0.000 n=15+15)
Throughput/DynamicPacket/16MB/TLSv12-8   42.3ms ± 3%   42.1ms ± 3%    ~     (p=0.505 n=14+15)
Throughput/DynamicPacket/16MB/TLSv13-8   42.7ms ± 3%   43.3ms ± 7%    ~     (p=0.123 n=15+14)
Throughput/DynamicPacket/32MB/TLSv12-8   82.8ms ± 3%   81.9ms ± 3%    ~     (p=0.112 n=14+15)
Throughput/DynamicPacket/32MB/TLSv13-8   84.6ms ± 6%   83.9ms ± 4%    ~     (p=0.624 n=15+15)
Throughput/DynamicPacket/64MB/TLSv12-8    166ms ± 4%    163ms ± 6%    ~     (p=0.081 n=15+15)
Throughput/DynamicPacket/64MB/TLSv13-8    165ms ± 3%    168ms ± 3%  +1.56%  (p=0.029 n=15+15)

Change-Id: I22409b05afe761b8ed1912b15c67fc03f88d3d1f
Reviewed-on: https://go-review.googlesource.com/c/go/+/203481
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #35157 (the bug there was fixed by CL200861)

Change-Id: I67069207b4cdc2ad4a475dd0bbc8555ecc5f534f
Reviewed-on: https://go-review.googlesource.com/c/go/+/203598
Run-TryBot: Giovanni Bajo <rasky@develer.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>

Sometimes, poset needs to collapse a path making all nodes in
the path aliases. For instance, we know that A<=N1<=B and we
learn that B<=A, we can deduce A==N1==B, and thus we can
collapse all paths from A to B into a single aliased node.

Currently, this is a TODO. This CL implements the path-collapsing
primitive by doing a DFS walk to build a bitset of all nodes
across all paths, and then calling the new aliasnodes that allow
to mark multiple nodes as aliases of a single master node.

This helps only 4 times in std+cmd, but it will be fundamental
when we will rely on poset to calculate numerical limits, to
calculate the correct values.

This also fixes #35157, a bug uncovered by a previous CL in this
serie. A testcase will be added soon.

Change-Id: I5fc54259711769d7bd7c2d166a5abc1cddc26350
Reviewed-on: https://go-review.googlesource.com/c/go/+/200861
Run-TryBot: Giovanni Bajo <rasky@develer.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Change aliasnode into aliasnodes, to allow for recording
multiple aliases in a single pass. The nodes being aliased
are passed as bitset for performance reason (O(1) lookups).
It does look worse in the existing case of SetEqual where
we now need to allocate a bitset just for a single node,
but the new API will allow to fully implement a path-collapsing
primitive in next CL.

No functional changes, passes toolstash -cmp.

Change-Id: I06259610e8ef478106b36852464ed2caacd29ab5
Reviewed-on: https://go-review.googlesource.com/c/go/+/200860Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Giovanni Bajo <rasky@develer.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

In preparation for allowing to make multiple nodes as aliases
in a single pass, refactor aliasnode splitting out the case
in which one of the nodes is not in the post into a new
funciton (aliasnewnode).

No functional changes, passes toolstash -cmp

Change-Id: I19ca6ef8426f8aec9f2622b6151c5c617dbb25b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/200859Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Giovanni Bajo <rasky@develer.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Also a similar 'elapsed' function and its usages were deleted.

Fixes #19865.

Change-Id: Ib125365e69cf2eda60de64fa74290c8c7d1fd65a
Reviewed-on: https://go-review.googlesource.com/c/go/+/171730
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>