net/http: remove deadstore statement

Change-Id: Icfa3fd519df48f8d7d7aa3795535fd7e6aaa159f
Reviewed-on: https://go-review.googlesource.com/c/go/+/435936
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net: delete unused code

Change-Id: Id4c3a140d9619796aee1ba3214f7d5fce040b4e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/435935
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net/http: use time.Compare

Change-Id: I4730673130bdfbda9987dcb5869f421082f92150
Reviewed-on: https://go-review.googlesource.com/c/go/+/435615
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debug/elf: fix typo in R_PPC64_TPREL34 and R_PPC64_DTPREL34

The suffix should be 34 not 28. I misread the name because the
reloc listed before these two in the ABI is named "R_PC64_PCREL28".

Updates #54345

Change-Id: Ie8238f55e441c787d70ead58e0a177c650f8b89e
Reviewed-on: https://go-review.googlesource.com/c/go/+/435415
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Run-TryBot: Paul Murphy <murp@ibm.com>
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go/types, types2: use "generic" rather than "parameterized" in error messages

Fix a couple of places where we still use "parameterized".

Change-Id: I2c70356d4e363ee709c5ef19ec8786956d5e9001
Reviewed-on: https://go-review.googlesource.com/c/go/+/436815
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cmd: add skips as needed to get tests to pass on js/wasm

For #54219.

Change-Id: I9767f46a5b44beeee62a3d53c4de4f6acb6b6e73
Reviewed-on: https://go-review.googlesource.com/c/go/+/436816
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Reviewed-by: Than McIntosh <thanm@google.com>
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os/exec: avoid leaking a process in TestDoubleStartLeavesPipesOpen

Updates #52580.
For #50436.

Change-Id: I0929055ffca1ca429f6ebec7d877f4268bd1fda2
Reviewed-on: https://go-review.googlesource.com/c/go/+/436656
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errors, fmt: add support for wrapping multiple errors

An error which implements an "Unwrap() []error" method wraps all the
non-nil errors in the returned []error.

We replace the concept of the "error chain" inspected by errors.Is
and errors.As with the "error tree". Is and As perform a pre-order,
depth-first traversal of an error's tree. As returns the first
matching result, if any.

The new errors.Join function returns an error wrapping a list of errors.

The fmt.Errorf function now supports multiple instances of the %w verb.

For #53435.

Change-Id: Ib7402e70b68e28af8f201d2b66bd8e87ccfb5283
Reviewed-on: https://go-review.googlesource.com/c/go/+/432898
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Rob Pike <r@golang.org>
Run-TryBot: Damien Neil <dneil@google.com>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>

cmd/go/internal/lockedfile/internal/filelock: remove unused type token

Change-Id: If815d17851e4e4eac026417b820f15d11939d9cc
Reviewed-on: https://go-review.googlesource.com/c/go/+/436595
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cmd/compile: limit goroutine count to parallelism

When the compiler crashes, it is not uncommon to see many hundreds
of goroutines all blocked waiting their turn to be one of the nWorkers
goroutines that is allowed to run. All these goroutine stacks are not a
terribly efficient use of memory, and they also make the crash dumps
hard to read.

Introduce a manager goroutine to hand out work to at most nWorker
goroutines, maintaining pending work in a local slice, rather than
having all those blocked goroutines hanging around waiting to run.

Change-Id: I46cb4e1afd6392805f359e14554ebc17d538bcba
Reviewed-on: https://go-review.googlesource.com/c/go/+/431956
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
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cmd/{cover,go}: avoid use of os.PathListSeparator in cmd/cover flag

Rework the mechanism for passing a list of output files from cmd/go to
cmd/cover when running new-style package-scope coverage
instrumentation (-pkgcfg mode). The old scheme passed a single string
with all output files joined together with os.PathListSeparator, but
this scheme is not viable on plan9, where strings containing the
separator character are not permitted when running exec.Command().
Instead, switch cmd/cover to use an arguments file (a file containing
a list of names) to specify names of instrumented output files. This
fixes the cmd/cover test failures on the plan9 builders.

Updates #51430.

Change-Id: I919f5e0a79500e28648fb9177225a9b938e4fdee
Reviewed-on: https://go-review.googlesource.com/c/go/+/436675
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go/types, types2: more concise error messages for cycle errors

If a cycle has length 1, don't enumerate the single cycle entry;
instead just mention "refers to itself". For instance, for an
invalid recursive type T we now report:

invalid recursive type: T refers to itself

instead of:

invalid recursive type T
T refers to
T

Adjust tests to check for the different error messages.

Change-Id: I5bd46f62fac0cf167f0d0c9a55f952981d294ff4
Reviewed-on: https://go-review.googlesource.com/c/go/+/436295
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runtime/coverage: apis to emit counter data under user control

Add hooks/apis to support writing of coverage counter data and
meta-data under user control (from within an executing "-cover"
binary), so as to provide a way to obtain coverage data from programs
that do not terminate. This patch also adds a hook for clearing the
coverage counter data for a running program, something that can be
helpful when the intent is to capture coverage info from a specific
window of program execution.

Updates #51430.

Change-Id: I34ee6cee52e5597fa3698b8b04f1b34a2a2a418f
Reviewed-on: https://go-review.googlesource.com/c/go/+/401236
Reviewed-by: David Chase <drchase@google.com>

cmd{cover,covdata,go}: better coverage for tests that build tools

Some of the unit tests in Go's "cmd" tree wind up building a separate
copy of the tool being tested, then exercise the freshly built tool as
a way of doing regression tests. The intent is to make sure that "go
test" is testing the current state of the source code, as opposed to
whatever happened to be current when "go install <tool>" was last run.

Doing things this way is unfriendly for coverage testing. If I run "go
test -cover cmd/mumble", and the cmd/mumble test harness builds a
fresh copy of mumble.exe, any runs of that new executable won't
generate coverage data.

This patch updates the test harnesses to use the unit test executable
as a stand-in for the tool itself, so that if "go test -cover" is in
effect, we get the effect of building the tool executable for coverage
as well. Doing this brings up the overall test coverage number for
cmd/cover quite dramatically:

before change:

  $ go test -cover .
  ok   cmd/cover 1.100s coverage: 1.5% of statements

after change:

  $ go test -cover .
  ok   cmd/cover 1.299s coverage: 84.2% of statements

Getting this to work requires a small change in the Go command as
well, to set GOCOVERDIR prior to executing a test binary.

Updates #51430.

Change-Id: Ifcf0ea85773b80fcda794aae3702403ec8e0b733
Reviewed-on: https://go-review.googlesource.com/c/go/+/404299
Reviewed-by: Bryan Mills <bcmills@google.com>

runtime/coverage: improve unit tests

Add a testpoint to cover support routines used to help
implement "go test -cover".

Change-Id: Ic28bf884a4e0d2c0a6d8fd04fc29c0c949227f21
Reviewed-on: https://go-review.googlesource.com/c/go/+/432315
Reviewed-by: Bryan Mills <bcmills@google.com>

crypto: use fmt.Appendf

Change-Id: I022a221e2d73cd8c70e8e04b7046c388748646a5
Reviewed-on: https://go-review.googlesource.com/c/go/+/435696
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cmd/nm: use print-style not printf-style

Change-Id: Ic977026a99a825954117902051e59928de9ccbdb
Reviewed-on: https://go-review.googlesource.com/c/go/+/435947
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cmd/cgo: use strings.TrimSuffix

Change-Id: I97b5592c678c350fd77069d7c40a98864733707a
Reviewed-on: https://go-review.googlesource.com/c/go/+/435946
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cmd/cgo: delete unused code

Change-Id: I6007cc6363e22ffa5f9a8f0441a642fd85127397
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cmd/cgo: use strings.Contains instead of strings.Index

Change-Id: Iaa623dae50ccae36ad44af25899c6453b6108046
Reviewed-on: https://go-review.googlesource.com/c/go/+/435944
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cmd/asm: use strings.TrimSuffix

Change-Id: If08ce3f8534f5fb7ce97ec124bfeff937e65f63b
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cmd/asm: delete unused func newAddr

Change-Id: I62f38aa07e9c6e2f0947d23adc7a1b453277c790
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cmd/asm: optimize if statement to return directly

Change-Id: Ieb8fb7c623ecd8b9ddd15cdb6eb2c6326a9bbd3b
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cmd/asm: use opd.String() instead of fmt.Sprintf

Change-Id: Idbade74025bddb26ec3c10527de5af5dc2b8c1cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/435940
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os/exec: refactor goroutine error reporting

Use a separate channel to report the final error of the copying
goroutines, receiving a value only when all of the copying goroutines
have completed. In a followup change (CL 401835), that will allow
waiters to select on goroutine completion alongside other events (such
as Context cancellation).

Also mildly refactor the watchCtx helper method so that its structure
better matches what will be needed to implement WaitDelay.

For #50436.

Change-Id: I54b3997fb6931d204814d8382f0a388a67b520f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/435995
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os/exec: do not close pipes on a double-Start error

This fixes a bug introduced in CL 401834 in which calling Start twice
with pipes attached to a command would spuriously close those pipes
when returning the error from the second Start call.

For #50436.

Change-Id: I3563cc99c0a0987752190fef95da3e9927a76fda
Reviewed-on: https://go-review.googlesource.com/c/go/+/436095
Reviewed-by: Ian Lance Taylor <iant@google.com>
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encoding/gob: add top level security doc

Add a slightly expanded version of the Decoder type comment to the top
level package doc, which explains that this package is not designed
to be hardened against adversarial inputs.

Change-Id: I8b83433838c8235eb06ded99041fdf726c811ee5
Reviewed-on: https://go-review.googlesource.com/c/go/+/436096
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Reviewed-by: Damien Neil <dneil@google.com>

go/types, types2: consistently use "cause" instead of "reason" for error details (cleanup)

There were many more uses of the variable name "cause" than "reason"
to hold error message details. Consistently use "cause" throughout.

Accordingly, s/MissingMethodReason/MissingMethodCause/.

Change-Id: I171d784faabc66a4c58ba8944784204687595203
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go/types, types2: remove (C/c)ompilerErrorMessages flag - not needed anymore

Fixes #55326.

Change-Id: Ic300976ddf504224faadc5bae21736fe94dac6bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/435416
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Auto-Submit: Robert Griesemer <gri@google.com>
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cmd/compile: use "shifted operand %s (type %s) must be integer" for some shift errors

This matches what go/types and types2 report and it also matches
the compiler errors reported for some related shift problems.

For #55326.

Change-Id: Iee40e8d988d5a7f9ff2c49f019884d02485c9fdf
Reviewed-on: https://go-review.googlesource.com/c/go/+/436177
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cmd/compile: use "cannot use %s as %s value in %s: %s" error message

This is close to what the compiler used to say, except now we say
"as T value" rather than "as type T" which is closer to the truth
(we cannot use a value as a type, after all). Also, place the primary
error and the explanation (cause) on a single line.

Make respective (single line) adjustment to the matching "cannot
convert" error.

Adjust various tests.

For #55326.

Change-Id: Ib646cf906b11f4129b7ed0c38cf16471f9266b88
Reviewed-on: https://go-review.googlesource.com/c/go/+/436176
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go/types, types2: use "assignment mismatch: x variables but y values" error message

This matches current compiler behavior.

For #55326.

Change-Id: I7197cf4ce21e614291a1a2e1048dd78d0a232b64
Reviewed-on: https://go-review.googlesource.com/c/go/+/436175
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Robert Griesemer <gri@google.com>

go/ast: record start and end of file in File.File{Start,End}

This change causes the parser to record the positions of the first
and last character in the file in new ast.File fields FileStart
and FileEnd.

The behavior of the existing Pos() and End() methods,
which record the span of declarations, must remain unchanged
for compatibility.

Fixes golang/go#53202

Change-Id: I250b19e69f41e3590292c3fe6dea1943ec98f629
Reviewed-on: https://go-review.googlesource.com/c/go/+/427955
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Alan Donovan <adonovan@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>

cmd/dist: test cmd module on js/wasm

Most tests will be skipped anyway because 'go build' is not available,
but this ensures cmd will be build tested by TryBots for js/wasm.

For #25911
For #35220
For #54219

Change-Id: I09c75905c36311810eb1ae75eeee2fa6102c1c0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/435237
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

cmd/compile/internal/base: replace io/ioutil with os package

Change-Id: Ide7618b65fcff7947809051d51b993d330e35717
GitHub-Last-Rev: 298853a82006655fe4f226cc5bea3bc21613b832
GitHub-Pull-Request: golang/go#55914
Reviewed-on: https://go-review.googlesource.com/c/go/+/435537
Run-TryBot: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

testing: fail if T.Setenv is called via T.Run in a parallel test

The existing implementation can call to T.Setenv in T.Run even after
calling to T.Parallel, so I changed it to cause a panic in that case.

Fixes #55128

Change-Id: Ib89d998ff56f00f96a5ca218af071bd35fdae53a
Reviewed-on: https://go-review.googlesource.com/c/go/+/431101
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>

cmd/go: using strings.CutSuffix replace strings.HasSuffix and strings.TrimSuffix

Change-Id: I79854419091d6c5c5c2922a1f45a3c5589673f11
Reviewed-on: https://go-review.googlesource.com/c/go/+/435138
Run-TryBot: xie cui <523516579@qq.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>

cmd/link/internal/loadelf: add additional relocations for riscv64

These relocations are produced by clang/llvm.

Change-Id: I4820e7ed805d1b7341023b263c167a285ca32cf5
Reviewed-on: https://go-review.googlesource.com/c/go/+/431755
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
TryBot-Result: Gopher Robot <gobot@golang.org>

os/signal: disable GNU readline to deflake TestTerminalSignal

Fixes #55903.

Change-Id: I992865277fb6526929d6c7db2b3b8d22ca0760f2
GitHub-Last-Rev: fc6f28e17c3d6c5f16f1cc047e42ac0ceb60e769
GitHub-Pull-Request: golang/go#55904
Reviewed-on: https://go-review.googlesource.com/c/go/+/435735
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>

cmd/internal/obj/ppc64: remove unnecessary opcodes

This CL removes some opcode placeholders that do not correspond
to any existing instructions and hence create confusion. Some
instructions that are no longer valid like LDMX are also removed.
Any references to this instruction in ISA 3.0 are considered
as documentation errata.

Change-Id: Ib71a657099723bbe1db88873233ee573b5c42fe7
Reviewed-on: https://go-review.googlesource.com/c/go/+/429860
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Paul Murphy <murp@ibm.com>
Run-TryBot: Archana Ravindar <aravind5@in.ibm.com>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Archana Ravindar <aravind5@in.ibm.com>

all: fix some typos

Change-Id: I8b28aebbb9494b2c877139a4584a5a42253e3bea
GitHub-Last-Rev: e3703fd3a50b811785df75751472aa3ab098b3d1
GitHub-Pull-Request: golang/go#55902
Reviewed-on: https://go-review.googlesource.com/c/go/+/435617
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

cmd/compile: remove some lines from PPC64.rules

In CL 429035 Keith suggested removing some
rules that were covered by generic rules. This
follows up on that comment.

Change-Id: I57b6c9ae0cd85f33a0eb2fef8356575d3d7820fb
Reviewed-on: https://go-review.googlesource.com/c/go/+/430417
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

cmd/go: support new hybrid coverage instrumentation

If GOEXPERIMENT=coverageredesign is in effect, introduce a new
top-level '-cover' option to "go build" to turn on new-style hybrid
code coverage instrumentation. Similarly, use the new instrumentation
for "go test -cover".

The main effects of "-cover" under the hood are to instrument files at
the package level using cmd/cover and to pass additional options to
the compiler when building instrumented packages.

The previous workflow for "go tool -cover mypkg" would expand to a
series of "go tool cover" commands (one per file) followed by a single
package compilation command to build the rewritten sources.

With the new workflow, the Go command will pass all of the Go files in
a package to the cover tool as a chunk (along with a config file
containing other parameters), then the cover tool will write
instrumented versions of the sources along with another "output"
config with info on coverage variable names for the the compiler. The
Go command will then kick off the compiler on the modified source
files, also passing in the config file generated by cmd/cover.

Updates #51430.

Change-Id: Id65621ff6a8c70a30168c1412c2d6f805ff3b9e7
Reviewed-on: https://go-review.googlesource.com/c/go/+/355452
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

cmd/go: refactor package references in Builder.build

Refactor references to "a.Package" in Builder.build to be consistent,
e.g. all via the "p" helper variable. No change in functionality, this
is just intended to make the code more readable/consistent (since
prior to this point we had a random mix of "p" and "a.Package").

Change-Id: Ifea5ff9b314c39a0cf6e688511907d08cc56c603
Reviewed-on: https://go-review.googlesource.com/c/go/+/424819
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>

cmd/go: add hook to check for GOEXPERIMENT in script tests

Add a new hook to allow script tests to check whether a specific
GOEXPERIMENT is enabled.

Updates #51430.

Change-Id: Icdf39f845ff2c8b10c634d49e9c27bc90e7984f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/402174
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

cmd/cover: add hybrid instrumentation mode

Add a new mode of coverage instrumentation that works as a hybrid
between purely tool-based and purely compiler-based. The cmd/cover
tool still does source-to-source rewriting, but it also generates
information to be used by the compiler to do things like marking
meta-data vars as read-only.

In hybrid mode, the cmd/cover tool is invoked not on a single source
file but on all the files in a package, and is passed a config file
containing the import path of the package in question, along with
other parameters needed for the run. It writes a series of modified
files and an output config file to be passed to the compiler when
compiling the modified files.

Not completely useful by itself, still needs a corresponding set of
changes in the Go command and in the compiler.

Updates #51430.

Change-Id: I0fcbd93a9a8fc25064187b159152486a2549ea54
Reviewed-on: https://go-review.googlesource.com/c/go/+/395896
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

runtime/coverage: runtime routines to emit coverage data

This patch fleshes out the runtime support for emitting coverage data
at the end of a run of an instrumented binary. Data is emitted in the
form of a pair of files, a meta-out-file and counter-data-outfile,
each written to the dir GOCOVERDIR. The meta-out-file is emitted only
if required; no need to emit again if an existing meta-data file with
the same hash and length is present.

Updates #51430.

Change-Id: I59d20a4b8c05910c933ee29527972f8e401b1685
Reviewed-on: https://go-review.googlesource.com/c/go/+/355451
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Than McIntosh <thanm@google.com>

cmd/covdata: add tools to read/manipulate coverage data files

Add a set of helper packages for reading collections of related
meta-data and counter-data files ("pods") produced by runs of
coverage-instrumented binaries, and a new tool program (cmd/covdata)
for dumping and/or manipulating coverage data files.

Currently "go tool covdata" subcommands include 'merge', 'intersect',
'percent', 'pkglist', 'subtract', 'debugdump', and 'textfmt'
(conversion to the legacy "go tool cover" format).

Updates #51430.

Change-Id: I44167c578f574b4636ab8726e726388531fd3258
Reviewed-on: https://go-review.googlesource.com/c/go/+/357609
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

go/types, types2: use "invalid operation: x rel y (cause)" for comparison error messages

Matches compiler behavior and is consistent with what we do with other
binary operations.

While at it, also use parentheses rather than a colon for a couple of
errors caused by not having a core type.

For #55326.

Change-Id: I0a5cec1a31ffda98d363e5528791965a1ccb5842
Reviewed-on: https://go-review.googlesource.com/c/go/+/435618
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>

time: add comment explaining >>33 in Now

Change-Id: I022b617cd345b412bee0b50a862676a1dca94e01
Reviewed-on: https://go-review.googlesource.com/c/go/+/418376
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

cmd/nm, runtime/cgo: add cgo support for freebsd/riscv64

Updates #53466

Change-Id: I08ea279c905e265a579b6b3e23aee012165beaee
Reviewed-on: https://go-review.googlesource.com/c/go/+/431658
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Goutnik <dgoutnik@gmail.com>

cmd/dist: enable cgo tests on freebsd/riscv64

Updates #53466

Change-Id: I17a41adb93c22fa84a7bdcec9d8c65001c5a8ba9
Reviewed-on: https://go-review.googlesource.com/c/go/+/431657
Reviewed-by: Dmitri Goutnik <dgoutnik@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Meng Zhuo <mzh@golangcn.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

crypto: use bytes.Clone

Change-Id: I92e110023739c6f8f7815c7e47ad7639c4e8812d
Reviewed-on: https://go-review.googlesource.com/c/go/+/435279
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: xie cui <523516579@qq.com>

net/textproto: use bytes.Clone

Change-Id: Ic73d667a98df3f2d1705a67e7e8625c6ba65cc0a
Reviewed-on: https://go-review.googlesource.com/c/go/+/435284
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>

internal: use bytes.Clone

Change-Id: Ia96ddd520a7bd2fd53bff55315c6fac04ae96a2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/435282
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>

encoding/xml: use bytes.Clone

Change-Id: I3218b1e3f8869f579facddb29471df13c835dc66
Reviewed-on: https://go-review.googlesource.com/c/go/+/435281
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>

runtime: add support for freebsd/riscv64

Updates #53466

Change-Id: I42ca5f1d0f20b5ecfcfba70d298566b6c851fefc
Reviewed-on: https://go-review.googlesource.com/c/go/+/431656
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Meng Zhuo <mzh@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Goutnik <dgoutnik@gmail.com>

database: use bytes.Clone

Change-Id: I66aad199884cffd51946f53f01580a3a353f5c97
Reviewed-on: https://go-review.googlesource.com/c/go/+/435280
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Meng Zhuo <mzh@golangcn.org>

crypto/rsa,crypto/internal/boring: fix PSS salt handling

Fix the coversion between our sentinel salt length variables and the
BoringSSL versions in SignRSAPSS. We previously set -1 (hash length
equals salt length) when 0 was passed when we should've been setting
-2. This now matches the conversion that happens in VerifyRSAPSS. Also
adds a note documenting why we do this.

Additionally in non-Boring mode, properly handle passing of salt lengths
with a negative value which aren't one of the magic constants, returning
an error instead of panicking.

See https://commondatastorage.googleapis.com/chromium-boringssl-docs/rsa.h.html#RSA_sign_pss_mgf1
for the BoringSSL docs.

Fixes #54803

Change-Id: Id1bd14dcf0ef4733867367257830ed43e25ef882
Reviewed-on: https://go-review.googlesource.com/c/go/+/426659
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Roland Shoemaker <roland@golang.org>

go/types, types2: use 2nd operand position for comparison type mismatch errors

When a comparison is invalid due to mismatched types, we only know
when we see the 2nd operand; so use that operand's position for the
error message. This matches compiler behavior.

For #55326.

Change-Id: I79450756bbdd2b4bb90ed4e960a451be0197b186
Reviewed-on: https://go-review.googlesource.com/c/go/+/435555
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

debug/elf: return error on reading from SHT_NOBITS sections

An SHT_NOBITS section contains no bytes and occupies no space in the
file. This change makes it return an error on reading from this section
so that it will force the caller to check for an SHT_NNOBITS section.

We have considered another option to return "nil, nil" for the Data
method. It's abandoned because it might lead a program to simply do
the wrong thing, thinking that the section is empty.

Please note that it breaks programs which expect a byte slice with the
length described by the sh_size field. There are two reasons to
introduce this breaking change: 1. SHT_NOBITS means no data and it's
unnecessary to allocate memory for it; 2. it could result in an OOM if
the file is corrupted and has a huge sh_size.

Fixes #54967.

Change-Id: I0c3ed4e097214fe88413d726a89122105ad45d4f
GitHub-Last-Rev: 994c12d9da8c7029ce1d26eb1eb4d333ef3b1f97
GitHub-Pull-Request: golang/go#54994
Reviewed-on: https://go-review.googlesource.com/c/go/+/429601
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

crypto/x509: use unsafe.Slice

Change-Id: I40fdfbd5cfb9f5ccb80d55bca28ff9ba1ec490f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/435285
Run-TryBot: Ian Lance Taylor <iant@golang.org>
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Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
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cmd/compile: use "method T.m already declared" for method redeclaration errors

Compromise between old compiler error "T.m redeclared in this block"
(where the "in this block" is not particularly helpful) and the old
type-checker error "method m already declared for type T ...".
In the case where we have position information for the original
declaration, the error message is "method T.m already declared at
<position>". The new message is both shorter and more precise.

For #55326.

Change-Id: Id4a7f326fe631b11db9e8030eccb417c72d6c7db
Reviewed-on: https://go-review.googlesource.com/c/go/+/435016
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go/types, types2: use "unknown field f in struct literal of type S" in error messages

This is a compromise of the error reported by the compiler (quotes
around field name removed) and the error reported by the type checkers
(added mention of struct type).

For #55326.

Change-Id: Iac4fb5c717f17c6713e90d327d39e68d3be40074
Reviewed-on: https://go-review.googlesource.com/c/go/+/434815
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go/types, types2: use "multiple-value" instead "n-valued" in error messages

This matches current compiler behavior.

For #55326.

Change-Id: I9ebe2914323072b5454fb9af2d15c9dd2d711bad
Reviewed-on: https://go-review.googlesource.com/c/go/+/434735
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go/types, types2: uniformly use "cannot convert X to type T"

This matches current compiler behavior.

For #55326.

Change-Id: I660bd15f13a8d9eb00fafa937f8261e664b0e065
Reviewed-on: https://go-review.googlesource.com/c/go/+/433276
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go/types, types2: use "and not used" instead of "but not used" in error messages

This matches longstanding compiler behavior.

Also, for unused packages, report:

`"pkg" imported and not used`
`"pkg" imported as X and not used`

This matches the other `X declared and not used` errors.

For #55326.

Change-Id: Ie71cf662fb5f4648449c64fc51bede298a1bdcbf
Reviewed-on: https://go-review.googlesource.com/c/go/+/432557
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cmd/compile: rework PPC64 Mul64uhilo lowering rules

Remove OpPPC64LoweredMuluhilo as this operation can be done
more efficiently with MULHDU and MULLD directly. This has the
benefit of not needing to use tuple select operations, and giving
the scheduler more freedom to place these operations.

The primary reason to avoid using tuples here is to to avoid
suboptimal scheduling when carry ops (e.x ADDC/ADDE) are used in
the same block as 64->128b multiples. CL 432275 modifies the
scheduling priorities which may cause non-flag/non-carry generating
tuple ops to interfere with carry opcodes. Thus resulting in excess
saving and restoring of the XER register.

This allows CL 432275 to adjust the scheduling priorities without
having to workaround odd tuple scheduling behavior.

Change-Id: Id04ef009ec4b86416e5436f2b44ae1474e73720e
Reviewed-on: https://go-review.googlesource.com/c/go/+/434855
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cmd/compile: make a type-specialized copy of encoding/binary.ReadUvarint

This is to get better escape analysis for a frequently-allocated object.

Change-Id: I1942a4e1c3cd1f0fa870bc8433a0165c18ce9c75
Reviewed-on: https://go-review.googlesource.com/c/go/+/435336
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cmd/compile: introduce "temporary" readers for more storage reuse

Change-Id: Id05d6099624284a9c1583b066d1a703e806b1e22
Reviewed-on: https://go-review.googlesource.com/c/go/+/433037
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Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
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cmd/compile: use stricter rule for possible partial overlap

Partial overlaps can only happen for strict sub-pieces of larger arrays.
That's a much stronger condition than the current optimization rules.

Update #54467

Change-Id: I11e539b71099e50175f37ee78fddf69283f83ee5
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go/scanner: emit implicit semicolon tokens in correct order

Prior to this change, the scanner, in ScanComments mode, would emit
the implicit SEMICOLON token generated by a newline ahead of any
immediately preceding comment "tokens". For example:

 foo /*a*/ /*b*/ /*c*/ \n   =>  [IDENT SEMICOLON COMMENT COMMENT COMMENT]

Now, tokens and comments are emitted by the scanner in lexical order
of their start position. SEMICOLON tokens corresponding to newlines
always have the position of the newline (even in the special case
in which the newline is in the middle of a general comment /*\n*/).

The scanner no longer needs to look ahead, possibly across multiple
comments, for a newline, when it encounters a comment.
The scanner semicolon tests have been rewritten to be less magical.

The parser must now expect line comments before an implicit semicolon.
Line comments for an explicit semicolon still appear after.
The new assertions in the parser TestLeadAndLineComments are
not changes to behavior.

Fixes golang/go#54941

Change-Id: Iffe97fd10e9e0b52882da8659307698ccb31c093
Reviewed-on: https://go-review.googlesource.com/c/go/+/429635
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bufio: use bytes.Clone

Change-Id: Ic21d979da8be1a6047b9bcd65b5ee71ca2ef7548
Reviewed-on: https://go-review.googlesource.com/c/go/+/435278
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cmd/link: fix coverage counter issue on AIX

Update the linker's XCOFF writer to handle coverage counter sections
properly; they need to be treated as bss, not data. Fixes a problem
with the aix-ppc64 builder introduced in CL 401235), e.g.
"runtime.covctrs: A symbol with type XTY_SD must be in a .text or
.data section".

Updates #51430.

Change-Id: I3fc385a37e2549c46cc7cc3b4718af989a36752a
Reviewed-on: https://go-review.googlesource.com/c/go/+/435335
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cmd/internal/pkgpath: use MustHaveExec in TestToSymbolFunc

ToSymbolFunc executes a command using exec.Command.

Change-Id: Ic6c274bdc23050d021ec98ba67748338ac34f12c
Reviewed-on: https://go-review.googlesource.com/c/go/+/435236
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cmd/api: skip tests on platforms that cannot exec

These tests execute commands using exec.Command.

Change-Id: I2708d6d24762fe2b2a902b1b221cc67392bf5c41
Reviewed-on: https://go-review.googlesource.com/c/go/+/435235
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cmd/link: refactor usage of SymLocalentry helper functions

PPC64 ELFv2 uses the st_other field of a symbol to specify an offset
from the global entry point to its local entry point. Similarly, some
values (i.e 1) may also require additional linker support which is
missing today.

For now, generate an error if we encounter unsupported local entry
values on PPC64, and update the Localentry values to use bytes, not
32b instruction words.

Similarly, ELFv2 1.5 also updates the wording of values 2-6. They
now map to a specific number of bytes.

Change-Id: Id1b71c3b0fea982bdcfb7eac91d9f93e04ae43f9
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misc/wasm: update deprecated substr usage

String.prototype.substr is deprecated and usage is no longer
recommended so using String.prototype.substring instead.

Change-Id: I9eb49a8c065890df73301e3a04af59f550bc3ae1
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runtime: using bytes.CutPrefix

Change-Id: I3f2dae17496b5b4efbdc022802f941a616abd87a
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cmd/compile: abstract type type+value obtained from types2

In preparation for encoding it in a more efficient way.

Change-Id: I299dd2befc3d07107a1b7b49225bbb9f2e48a343
Reviewed-on: https://go-review.googlesource.com/c/go/+/432896
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bytes,strings: optimize Repeat

When generating long strings or slices with Repeat we
currently reuse intermediate states as a way to quickly
build exponentially longer results.

This works well as long as the intermediate states fit into
the processor D-cache. If they don't we start thrashing the
D-cache by reading in the whole intermediate state over and
over on each iteration.

Instead, once we reach a large enough intermediate state (that
allows the memcpy operation to perform at peak) we cap the
size of chunk of the state that is used as source for subsequent
appends. This ensures that this smaller source chunk is always
present in the D-cache, and the append operation does not need
to read the state contents from memory.

Currently the cap is set to 8KB, a number derived via
experimentation to yield the highest performance across a
a large range of result sizes. Slightly higher caps also
produced similar results: 8KB was chosen as the smallest one
in this performance plateau with the intention to minimize
D-cache pollution.

For result sizes larger than the fastest cache levels we get
significantly higher performance compared to the current
implementation:
strings:
name                            old speed      new speed      delta
RepeatLarge/256/1-16            1.73GB/s ± 1%  1.73GB/s ± 0%      ~     (p=0.556 n=5+4)
RepeatLarge/256/16-16           2.02GB/s ± 0%  1.95GB/s ± 8%      ~     (p=0.222 n=5+5)
RepeatLarge/512/1-16            2.30GB/s ±13%  2.47GB/s ± 1%      ~     (p=0.548 n=5+5)
RepeatLarge/512/16-16           2.38GB/s ±16%  2.77GB/s ± 1%   +16.27%  (p=0.032 n=5+5)
RepeatLarge/1024/1-16           3.17GB/s ± 1%  3.18GB/s ± 0%      ~     (p=0.730 n=4+5)
RepeatLarge/1024/16-16          3.39GB/s ± 2%  3.38GB/s ± 1%      ~     (p=0.548 n=5+5)
RepeatLarge/2048/1-16           3.32GB/s ± 2%  3.32GB/s ± 2%      ~     (p=1.000 n=5+5)
RepeatLarge/2048/16-16          3.41GB/s ± 4%  3.46GB/s ± 2%      ~     (p=0.310 n=5+5)
RepeatLarge/4096/1-16           3.60GB/s ± 4%  3.67GB/s ± 3%      ~     (p=0.690 n=5+5)
RepeatLarge/4096/16-16          3.74GB/s ± 3%  3.71GB/s ± 5%      ~     (p=0.690 n=5+5)
RepeatLarge/8192/1-16           3.94GB/s ± 4%  4.01GB/s ± 1%      ~     (p=0.222 n=5+5)
RepeatLarge/8192/16-16          3.94GB/s ± 6%  4.05GB/s ± 1%      ~     (p=0.222 n=5+5)
RepeatLarge/8192/4097-16        4.25GB/s ± 6%  4.32GB/s ± 3%      ~     (p=0.690 n=5+5)
RepeatLarge/16384/1-16          4.96GB/s ± 1%  5.02GB/s ± 2%      ~     (p=0.421 n=5+5)
RepeatLarge/16384/16-16         4.99GB/s ± 2%  5.07GB/s ± 1%      ~     (p=0.421 n=5+5)
RepeatLarge/16384/4097-16       5.15GB/s ± 3%  5.17GB/s ± 1%      ~     (p=1.000 n=5+5)
RepeatLarge/32768/1-16          5.44GB/s ± 2%  5.42GB/s ± 1%      ~     (p=0.841 n=5+5)
RepeatLarge/32768/16-16         5.46GB/s ± 4%  5.44GB/s ± 1%      ~     (p=0.905 n=5+4)
RepeatLarge/32768/4097-16       4.84GB/s ± 2%  4.59GB/s ±12%    -5.05%  (p=0.032 n=5+5)
RepeatLarge/65536/1-16          5.85GB/s ± 0%  5.84GB/s ± 1%      ~     (p=0.690 n=5+5)
RepeatLarge/65536/16-16         5.81GB/s ± 2%  5.84GB/s ± 2%      ~     (p=0.421 n=5+5)
RepeatLarge/65536/4097-16       5.38GB/s ± 6%  5.45GB/s ± 1%      ~     (p=1.000 n=5+5)
RepeatLarge/131072/1-16         6.20GB/s ± 1%  6.31GB/s ± 1%    +1.80%  (p=0.008 n=5+5)
RepeatLarge/131072/16-16        6.12GB/s ± 3%  6.25GB/s ± 3%      ~     (p=0.095 n=5+5)
RepeatLarge/131072/4097-16      5.95GB/s ± 1%  5.85GB/s ±10%      ~     (p=1.000 n=5+5)
RepeatLarge/262144/1-16         6.33GB/s ± 1%  6.56GB/s ± 0%    +3.62%  (p=0.016 n=5+4)
RepeatLarge/262144/16-16        6.42GB/s ± 0%  6.65GB/s ± 1%    +3.58%  (p=0.016 n=4+5)
RepeatLarge/262144/4097-16      6.31GB/s ± 1%  6.44GB/s ± 1%    +1.94%  (p=0.008 n=5+5)
RepeatLarge/524288/1-16         6.23GB/s ± 1%  6.92GB/s ± 3%   +11.02%  (p=0.008 n=5+5)
RepeatLarge/524288/16-16        6.24GB/s ± 1%  6.97GB/s ± 2%   +11.77%  (p=0.016 n=4+5)
RepeatLarge/524288/4097-16      6.14GB/s ± 2%  6.73GB/s ± 3%    +9.50%  (p=0.008 n=5+5)
RepeatLarge/1048576/1-16        5.23GB/s ± 1%  6.53GB/s ± 6%   +24.85%  (p=0.008 n=5+5)
RepeatLarge/1048576/16-16       5.21GB/s ± 1%  6.56GB/s ± 4%   +25.93%  (p=0.008 n=5+5)
RepeatLarge/1048576/4097-16     5.22GB/s ± 1%  6.26GB/s ± 2%   +20.09%  (p=0.008 n=5+5)
RepeatLarge/2097152/1-16        3.95GB/s ± 1%  5.96GB/s ± 1%   +51.01%  (p=0.008 n=5+5)
RepeatLarge/2097152/16-16       3.94GB/s ± 1%  5.98GB/s ± 2%   +51.99%  (p=0.008 n=5+5)
RepeatLarge/2097152/4097-16     4.94GB/s ± 1%  5.71GB/s ± 2%   +15.63%  (p=0.008 n=5+5)
RepeatLarge/4194304/1-16        3.10GB/s ± 1%  5.89GB/s ± 1%   +89.90%  (p=0.008 n=5+5)
RepeatLarge/4194304/16-16       3.09GB/s ± 1%  5.86GB/s ± 1%   +89.89%  (p=0.008 n=5+5)
RepeatLarge/4194304/4097-16     3.13GB/s ± 1%  5.89GB/s ± 1%   +88.36%  (p=0.008 n=5+5)
RepeatLarge/8388608/1-16        3.06GB/s ± 1%  6.31GB/s ±16%  +105.84%  (p=0.008 n=5+5)
RepeatLarge/8388608/16-16       3.08GB/s ± 1%  6.62GB/s ± 1%  +114.66%  (p=0.008 n=5+5)
RepeatLarge/8388608/4097-16     3.13GB/s ± 2%  6.87GB/s ± 1%  +119.62%  (p=0.008 n=5+5)
RepeatLarge/16777216/1-16       3.21GB/s ± 3%  5.88GB/s ± 1%   +83.27%  (p=0.008 n=5+5)
RepeatLarge/16777216/16-16      3.23GB/s ± 2%  5.84GB/s ± 2%   +80.49%  (p=0.008 n=5+5)
RepeatLarge/16777216/4097-16    3.30GB/s ± 6%  5.88GB/s ± 2%   +78.18%  (p=0.008 n=5+5)
RepeatLarge/33554432/1-16       3.71GB/s ± 3%  5.91GB/s ± 2%   +59.17%  (p=0.008 n=5+5)
RepeatLarge/33554432/16-16      3.67GB/s ± 3%  5.91GB/s ± 2%   +61.13%  (p=0.008 n=5+5)
RepeatLarge/33554432/4097-16    3.71GB/s ± 1%  5.77GB/s ± 6%   +55.51%  (p=0.008 n=5+5)
RepeatLarge/67108864/1-16       4.61GB/s ±11%  6.00GB/s ± 5%   +30.15%  (p=0.008 n=5+5)
RepeatLarge/67108864/16-16      4.62GB/s ± 7%  6.11GB/s ± 2%   +32.35%  (p=0.008 n=5+5)
RepeatLarge/67108864/4097-16    4.71GB/s ± 2%  6.24GB/s ± 2%   +32.60%  (p=0.008 n=5+5)
RepeatLarge/134217728/1-16      4.53GB/s ± 8%  6.28GB/s ±11%   +38.57%  (p=0.008 n=5+5)
RepeatLarge/134217728/16-16     4.78GB/s ± 3%  6.36GB/s ± 3%   +33.16%  (p=0.008 n=5+5)
RepeatLarge/134217728/4097-16   4.73GB/s ± 6%  6.46GB/s ± 3%   +36.63%  (p=0.008 n=5+5)
RepeatLarge/268435456/1-16      4.09GB/s ±25%  6.37GB/s ±19%   +56.00%  (p=0.008 n=5+5)
RepeatLarge/268435456/16-16     4.50GB/s ± 4%  6.86GB/s ± 0%   +52.49%  (p=0.016 n=5+4)
RepeatLarge/268435456/4097-16   4.73GB/s ± 5%  6.90GB/s ± 0%   +45.94%  (p=0.008 n=5+5)
RepeatLarge/536870912/1-16      4.38GB/s ±36%  6.52GB/s ± 8%   +48.68%  (p=0.008 n=5+5)
RepeatLarge/536870912/16-16     4.69GB/s ±12%  6.90GB/s ± 1%   +46.97%  (p=0.008 n=5+5)
RepeatLarge/536870912/4097-16   4.87GB/s ± 8%  6.98GB/s ± 0%   +43.36%  (p=0.008 n=5+5)
RepeatLarge/1073741824/1-16     3.87GB/s ±28%  6.96GB/s ± 1%   +79.94%  (p=0.016 n=5+4)
RepeatLarge/1073741824/16-16    4.79GB/s ± 9%  6.93GB/s ± 0%   +44.79%  (p=0.008 n=5+5)
RepeatLarge/1073741824/4097-16  4.65GB/s ± 8%  7.02GB/s ± 1%   +51.02%  (p=0.008 n=5+5)

bytes:
name                            old speed      new speed      delta
RepeatLarge/256/1-16            1.93GB/s ± 1%  1.84GB/s ± 1%    -4.81%  (p=0.000 n=10+10)
RepeatLarge/256/16-16           2.25GB/s ± 2%  2.15GB/s ± 1%    -4.45%  (p=0.000 n=9+8)
RepeatLarge/512/1-16            2.71GB/s ± 1%  2.62GB/s ± 1%    -3.27%  (p=0.000 n=10+9)
RepeatLarge/512/16-16           2.96GB/s ± 4%  2.91GB/s ± 1%      ~     (p=0.243 n=9+10)
RepeatLarge/1024/1-16           3.35GB/s ± 1%  3.27GB/s ± 1%    -2.61%  (p=0.000 n=9+10)
RepeatLarge/1024/16-16          3.56GB/s ± 2%  3.52GB/s ± 1%    -1.10%  (p=0.010 n=10+9)
RepeatLarge/2048/1-16           3.52GB/s ± 1%  3.45GB/s ± 1%    -1.92%  (p=0.000 n=10+10)
RepeatLarge/2048/16-16          3.61GB/s ± 1%  3.58GB/s ± 0%    -0.82%  (p=0.008 n=9+8)
RepeatLarge/4096/1-16           3.85GB/s ± 2%  3.80GB/s ± 2%      ~     (p=0.165 n=10+10)
RepeatLarge/4096/16-16          3.88GB/s ± 3%  3.84GB/s ± 4%      ~     (p=0.393 n=10+10)
RepeatLarge/8192/1-16           4.12GB/s ± 2%  4.04GB/s ± 1%    -1.96%  (p=0.000 n=10+10)
RepeatLarge/8192/16-16          4.11GB/s ± 2%  4.09GB/s ± 1%      ~     (p=0.278 n=9+10)
RepeatLarge/8192/4097-16        4.38GB/s ± 1%  4.39GB/s ± 4%      ~     (p=0.720 n=9+10)
RepeatLarge/16384/1-16          5.06GB/s ± 2%  4.95GB/s ± 3%    -2.29%  (p=0.001 n=10+9)
RepeatLarge/16384/16-16         5.11GB/s ± 3%  5.06GB/s ± 3%      ~     (p=0.315 n=10+9)
RepeatLarge/16384/4097-16       5.22GB/s ± 3%  5.26GB/s ± 3%      ~     (p=0.211 n=9+10)
RepeatLarge/32768/1-16          5.54GB/s ± 2%  5.50GB/s ± 3%      ~     (p=0.353 n=10+10)
RepeatLarge/32768/16-16         5.55GB/s ± 1%  5.60GB/s ± 1%    +0.91%  (p=0.035 n=10+9)
RepeatLarge/32768/4097-16       4.88GB/s ± 2%  4.85GB/s ± 2%      ~     (p=0.447 n=10+9)
RepeatLarge/65536/1-16          5.86GB/s ± 1%  5.93GB/s ± 2%    +1.18%  (p=0.043 n=8+10)
RepeatLarge/65536/16-16         5.83GB/s ± 2%  5.98GB/s ± 1%    +2.67%  (p=0.000 n=10+10)
RepeatLarge/65536/4097-16       5.57GB/s ± 0%  5.56GB/s ± 3%      ~     (p=0.696 n=8+10)
RepeatLarge/131072/1-16         6.23GB/s ± 1%  6.38GB/s ± 2%    +2.51%  (p=0.000 n=9+10)
RepeatLarge/131072/16-16        6.21GB/s ± 2%  6.37GB/s ± 1%    +2.72%  (p=0.000 n=9+10)
RepeatLarge/131072/4097-16      6.04GB/s ± 1%  6.09GB/s ± 3%      ~     (p=0.356 n=9+10)
RepeatLarge/262144/1-16         6.47GB/s ± 1%  6.63GB/s ± 2%    +2.57%  (p=0.003 n=10+10)
RepeatLarge/262144/16-16        6.45GB/s ± 2%  6.69GB/s ± 2%    +3.65%  (p=0.000 n=10+10)
RepeatLarge/262144/4097-16      6.35GB/s ± 1%  6.51GB/s ± 2%    +2.48%  (p=0.000 n=9+10)
RepeatLarge/524288/1-16         6.21GB/s ± 2%  6.95GB/s ± 1%   +11.95%  (p=0.000 n=10+10)
RepeatLarge/524288/16-16        6.24GB/s ± 2%  6.93GB/s ± 2%   +11.11%  (p=0.000 n=10+10)
RepeatLarge/524288/4097-16      6.18GB/s ± 2%  6.82GB/s ± 1%   +10.39%  (p=0.000 n=9+10)
RepeatLarge/1048576/1-16        5.34GB/s ± 2%  6.41GB/s ± 2%   +20.05%  (p=0.000 n=10+10)
RepeatLarge/1048576/16-16       5.33GB/s ± 1%  6.45GB/s ± 2%   +20.84%  (p=0.000 n=10+9)
RepeatLarge/1048576/4097-16     5.28GB/s ± 1%  6.17GB/s ± 2%   +16.75%  (p=0.000 n=10+10)
RepeatLarge/2097152/1-16        4.04GB/s ± 1%  6.21GB/s ± 1%   +53.89%  (p=0.000 n=9+8)
RepeatLarge/2097152/16-16       4.02GB/s ± 1%  6.20GB/s ± 2%   +54.37%  (p=0.000 n=10+9)
RepeatLarge/2097152/4097-16     4.94GB/s ± 1%  6.04GB/s ± 1%   +22.36%  (p=0.000 n=10+10)
RepeatLarge/4194304/1-16        3.10GB/s ± 1%  5.74GB/s ± 0%   +85.04%  (p=0.000 n=10+9)
RepeatLarge/4194304/16-16       3.10GB/s ± 2%  5.72GB/s ± 1%   +84.26%  (p=0.000 n=9+10)
RepeatLarge/4194304/4097-16     3.03GB/s ± 4%  5.61GB/s ± 1%   +85.06%  (p=0.000 n=10+9)
RepeatLarge/8388608/1-16        3.08GB/s ± 2%  6.25GB/s ± 1%  +103.09%  (p=0.000 n=9+9)
RepeatLarge/8388608/16-16       3.07GB/s ± 2%  6.26GB/s ± 3%  +104.07%  (p=0.000 n=10+9)
RepeatLarge/8388608/4097-16     3.08GB/s ± 2%  6.23GB/s ± 2%  +102.09%  (p=0.000 n=9+10)
RepeatLarge/16777216/1-16       3.25GB/s ± 2%  5.78GB/s ± 3%   +78.03%  (p=0.000 n=9+9)
RepeatLarge/16777216/16-16      3.25GB/s ± 1%  5.75GB/s ± 1%   +77.21%  (p=0.000 n=9+10)
RepeatLarge/16777216/4097-16    3.29GB/s ± 3%  5.72GB/s ± 2%   +73.74%  (p=0.000 n=10+10)
RepeatLarge/33554432/1-16       3.68GB/s ± 2%  5.90GB/s ± 1%   +60.20%  (p=0.000 n=10+10)
RepeatLarge/33554432/16-16      3.69GB/s ± 3%  5.88GB/s ± 1%   +59.54%  (p=0.000 n=10+9)
RepeatLarge/33554432/4097-16    3.74GB/s ± 1%  5.94GB/s ± 2%   +58.68%  (p=0.000 n=7+10)
RepeatLarge/67108864/1-16       4.62GB/s ±12%  6.11GB/s ± 3%   +32.23%  (p=0.000 n=10+9)
RepeatLarge/67108864/16-16      4.77GB/s ± 2%  6.09GB/s ± 2%   +27.88%  (p=0.000 n=9+9)
RepeatLarge/67108864/4097-16    4.78GB/s ± 1%  6.19GB/s ± 1%   +29.51%  (p=0.000 n=9+10)
RepeatLarge/134217728/1-16      4.60GB/s ±16%  6.52GB/s ± 9%   +41.67%  (p=0.000 n=10+10)
RepeatLarge/134217728/16-16     4.80GB/s ± 4%  6.81GB/s ± 2%   +41.82%  (p=0.000 n=10+9)
RepeatLarge/134217728/4097-16   4.79GB/s ± 4%  6.81GB/s ± 2%   +42.31%  (p=0.000 n=9+10)
RepeatLarge/268435456/1-16      4.43GB/s ±25%  6.27GB/s ±14%   +41.52%  (p=0.000 n=10+10)
RepeatLarge/268435456/16-16     4.75GB/s ± 4%  6.68GB/s ± 4%   +40.50%  (p=0.000 n=9+10)
RepeatLarge/268435456/4097-16   4.75GB/s ± 3%  6.58GB/s ± 4%   +38.68%  (p=0.000 n=9+10)
RepeatLarge/536870912/1-16      4.96GB/s ± 9%  6.39GB/s ±16%   +28.90%  (p=0.000 n=8+10)
RepeatLarge/536870912/16-16     4.66GB/s ± 6%  6.57GB/s ± 7%   +40.82%  (p=0.000 n=10+9)
RepeatLarge/536870912/4097-16   4.68GB/s ±11%  6.88GB/s ± 3%   +47.01%  (p=0.000 n=10+9)
RepeatLarge/1073741824/1-16     4.39GB/s ±23%  6.57GB/s ± 5%   +49.75%  (p=0.000 n=10+8)
RepeatLarge/1073741824/16-16    4.73GB/s ±13%  6.89GB/s ± 1%   +45.68%  (p=0.000 n=9+8)
RepeatLarge/1073741824/4097-16  4.97GB/s ±15%  6.73GB/s ± 9%   +35.45%  (p=0.000 n=10+10)

The results above come from a Intel i9-9980HK (256KB L2) with
TurboBoost disabled.

Change-Id: I79dd57da0429aee9020ffd7bc458a034b999b740
Reviewed-on: https://go-review.googlesource.com/c/go/+/419054
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

debug/elf: suport files with >= 65280 (0xff00) sections

The spec https://refspecs.linuxfoundation.org/elf/gabi4+/ch4.eheader.html
states:

1. e_shnum: If the number of sections is greater than or equal to
SHN_LORESERVE (0xff00), this member has the value zero and the actual
number of section header table entries is contained in the sh_size
field of the section header at index 0.

2. e_shstrndx: If the section name string table section index is
greater than or equal to SHN_LORESERVE (0xff00), this member has the
value SHN_XINDEX (0xffff) and the actual index of the section name
string table section is contained in the sh_link field of the section
header at index 0.

This CL makes these changes to support files with >= 0xff00 sections:

1. if shoff > 0 && shnum == 0, read sh_size from the initial section
header entry as shnum.
2. if shstrndx == SHN_XINDEX, read sh_link from the initial section
header entry as shstrndx.

It returns an error if the type of the initial section is not SHT_NULL.

A file with >= 0xff00 sections is too big to include in the repository,
so the test case constructs one on the fly, with some of the sections
zeroed out.

While here, remove the unnecessary use of reflect.DeepEqual in the test.

Fixes #55294.

Change-Id: I15ec43612c7cce6e8decfe4e81da3a5b16de47f7
GitHub-Last-Rev: 797c16480bc76524ff1a7c01ed09b759fcd7d45b
GitHub-Pull-Request: golang/go#55295
Reviewed-on: https://go-review.googlesource.com/c/go/+/432255
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

cmd: relocate search.MatchPattern to cmd/internal/pkgpattern

Relocate cmd/go's search.MatchPattern helper routine to a new package
in cmd/internal from its current location, as to allow it to be used
in other tools that accept package pattern command line flags. No
change in functionality along the way.

Updates #51430.

Change-Id: I726e974ccd66a055bb5a94497b36b8d68d47cad1
Reviewed-on: https://go-review.googlesource.com/c/go/+/432757
Reviewed-by: Bryan Mills <bcmills@google.com>

runtime/trace: add missing events for the locked g in extra M.

Extra Ms may lead to the "no consistent ordering of events possible" error when parsing trace file with cgo enabled, since:
1. The gs in the extra Ms may be in `_Gdead` status while starting trace by invoking `runtime.StartTrace`,
2. and these gs will trigger `traceEvGoSysExit` events in `runtime.exitsyscall` when invoking go functions from c,
3. then, the events of those gs are under non-consistent ordering, due to missing the previous events.

Add two events, `traceEvGoCreate` and `traceEvGoInSyscall`, in `runtime.StartTrace`, will make the trace parser happy.

Fixes #29707

Change-Id: I2fd9d1713cda22f0ddb36efe1ab351f88da10881
GitHub-Last-Rev: 7bbfddb81b70041250e3c59ce53bea44f7afd2c3
GitHub-Pull-Request: golang/go#54974
Reviewed-on: https://go-review.googlesource.com/c/go/+/429858
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: xie cui <523516579@qq.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Pratt <mpratt@google.com>

cmd/go/internal: use strings.CutSuffix

Updates #42537

Change-Id: I2d4c5e911c8a2ddfe9a976896b05d3cd8be61f6b
GitHub-Last-Rev: a87597d8a7a84c4975fb5e13004feda9b6abce34
GitHub-Pull-Request: golang/go#55830
Reviewed-on: https://go-review.googlesource.com/c/go/+/433275
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

reflect: clarify that Value.Comparable checks the value

For #46746

Change-Id: Ic7a31ddf7cd6bf6dd0db6b9eb3fee68fc180f72e
Reviewed-on: https://go-review.googlesource.com/c/go/+/435277
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

debug/dwarf: don't crash on invalid range/rnglist offset

No test case because the problem can only happen for invalid data. Let
the fuzzer find cases like this.

Fixes #53529

Change-Id: I318c87795e545fe5a006d16b4d361cd4bf5d502d
Reviewed-on: https://go-review.googlesource.com/c/go/+/434936
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

net/http: fix the potential leak of textproto.Reader from pool

Fixes #55835

Change-Id: I6109bab2941b859e8cfef22f65a6a3a5f977a8d7
Reviewed-on: https://go-review.googlesource.com/c/go/+/433835
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

image/gif,image/jpeg,image/png: skip FuzzDecode in testing short mode

The image/gif.FuzzDecode takes an excessive amount of time to run on various
builders - skip these in testing short mode. Likewise for image/jpeg and
image/png.

Fixes #55839

Change-Id: I1049d06b9dcbbc7dbc4f53d3c49b64e2254eabbd
Reviewed-on: https://go-review.googlesource.com/c/go/+/435175
Reviewed-by: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

internal/goroot: using strings.CutPrefix replace strings.HasPrefix and strings.TrimPrefix

Change-Id: I63b2af955e2ada6d20e72c10797576d93bbc7e71
Reviewed-on: https://go-review.googlesource.com/c/go/+/435135
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

all: replace [0-9] with \d in regexps

1. replace [0-9] with \d in regexps
2. replace [a-zA-Z0-9_] with \w in regexps

Change-Id: I9e260538252a0c1071e76aeb1c5f885c6843a431
GitHub-Last-Rev: 286e1a4619c4bdda7f461afbd6d30b9f312c0486
GitHub-Pull-Request: golang/go#54874
Reviewed-on: https://go-review.googlesource.com/c/go/+/428435
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>

runtime: add cgo guard for exit hooks test

Add an additional guard to ensure that we don't try to run the "-race"
variant of the exit hooks test when CGO is explicitly turned off via
CGO_ENABLED=0 (this fixes a failure on the no-cgo builder caused
by CL 354790).

Change-Id: I9dc7fbd71962e9a098916da69d9119a753f27116
Reviewed-on: https://go-review.googlesource.com/c/go/+/434935
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

cmd/go/internal: use time.DateTime constant

Use the newly defined time.Datetime constant instead of a string literal.

Updates #52746

Change-Id: I2722415ecc67fd2adfdab2eaba3298774032bff3
GitHub-Last-Rev: 65d3aa9bc229cf6d07d6d0c1aaee4ada9056cd49
GitHub-Pull-Request: golang/go#55833
Reviewed-on: https://go-review.googlesource.com/c/go/+/433277
Run-TryBot: Joseph Tsai <joetsai@digital-static.net>
Auto-Submit: Joseph Tsai <joetsai@digital-static.net>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

cmd/compile: add coverage fixup mode

Adds a -coveragecfg=<configfile> command line option to the compiler
to help support a cooperative "tool and compiler" mode for coverage
instrumentation. In this mode the cmd/cover tool generates most of the
counter instrumentation via source-to-source rewriting, but the
compiler fixes up the result if passed the "-coveragecfg" option. The
fixups include:

  - reclassifying counter variables (special storage class)
  - marking meta-data variables are read-only
  - adding in an init call to do registation

Updates #51430.

Change-Id: Iead72b85209725ee044542374465f118a3ee72e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/395895
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

cmd/compile,cmd/link: hooks for identifying coverage counters

Add a new "coverage counter" classification for variables to be used
for storing code coverage counter values (somewhat in the same way
that we identify fuzzer counters). Tagging such variables allows us to
aggregate them in the linker, and to treat updates specially.

Updates #51430.

Change-Id: Ib49fb05736ffece98bcc2f7a7c37e991b7f67bbb
Reviewed-on: https://go-review.googlesource.com/c/go/+/401235
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

all: use strings.CutPrefix

Updates #42537

Change-Id: Ice23d7d36bbede27551cbc086119694f6a3b5e4a
GitHub-Last-Rev: 0d65208313ea318725159186fad045fc6400fb25
GitHub-Pull-Request: golang/go#55347
Reviewed-on: https://go-review.googlesource.com/c/go/+/432895
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
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go/types, types2: report "undefined: p.x" instead of "x not declared by package p"

This matches the compiler's long-standing behavior.

For #55326.

Change-Id: Icd946b031b1b6e65498fb52bceb4a53807732463
Reviewed-on: https://go-review.googlesource.com/c/go/+/432556
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

go/types, types2: report "undefined: x" instead of "undeclared name: x"

This matches the compiler's long-standing behavior.

For #55326.

Change-Id: I90696a11f0b7d1f4be95a4b9a6f01844df2a2347
Reviewed-on: https://go-review.googlesource.com/c/go/+/432555
Run-TryBot: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

sync: clarify Cond.Wait documentation

The previous wording was unclear and seemingly contradictory.

Change-Id: I0781dc4525948f4e8e5698271362a82387688f81
GitHub-Last-Rev: c1e032fa9451dd50a69cf572cd80dcdbe6591d2e
GitHub-Pull-Request: golang/go#53516
Reviewed-on: https://go-review.googlesource.com/c/go/+/413774
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

runtime: add an exit hook facility

Add a new API (not public/exported) for registering a function with
the runtime that should be called when program execution terminates,
to be used in the new code coverage re-implementation. The API looks
like

  func addExitHook(f func(), runOnNonZeroExit bool)

The first argument is the function to be run, second argument controls
whether the function is invoked even if there is a call to os.Exit
with a non-zero status. Exit hooks are run in reverse order of
registration, e.g. the first hook to be registered will be the last to
run. Exit hook functions are not allowed to panic or to make calls to
os.Exit.

Updates #51430.

Change-Id: I906f8c5184b7c1666f05a62cfc7833bf1a4300c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/354790
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>