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57965 Commits

Author SHA1 Message Date
Austin Clements
88a6df72c9 cmd/internal/objabi: generalize "is runtime package" check
There are several implementations of "is this package path a runtime
package". They all have slightly different lists because they all care
about slightly different properties of building the runtime.

To start converging these, we replace objabi.IsRuntimePackagePath with
objabi.LookupPkgSpecial, which returns a struct we can extend with
various special build properties. We'll extend this with several other
flags in the following CLs.

Change-Id: I21959cb8c3d18a350d6060467681c72ea49af712
Reviewed-on: https://go-review.googlesource.com/c/go/+/521698
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
2023-08-22 19:18:26 +00:00
Austin Clements
72946ae867 cmd/asm,cmd/dist,cmd/go: remove asm -compiling-runtime flag
Currently, dist and go pass a -compiling-runtime flag to asm if
they're compiling a runtime package. However, now that we always pass
the package path to asm, it can make that determination just as well
as its callers can. This CL moves that check into asm and drops the
flag.

This in turn makes dist's copy of IsRuntimePackagePath unnecessary, so
we delete it.

Change-Id: I6ecf2d50b5b83965012af34dbe5f9a973ba0778b
Reviewed-on: https://go-review.googlesource.com/c/go/+/521697
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-22 19:18:23 +00:00
Austin Clements
596120fdc6 cmd/compile: redo IsRuntimePkg/IsReflectPkg predicate
Currently, the types package has IsRuntimePkg and IsReflectPkg
predicates for testing if a Pkg is the runtime or reflect packages.
IsRuntimePkg returns "true" for any "CompilingRuntime" package, which
includes all of the packages imported by the runtime. This isn't
inherently wrong, except that all but one use of it is of the form "is
this Sym a specific runtime.X symbol?" for which we clearly only want
the package "runtime" itself. IsRuntimePkg was introduced (as
isRuntime) in CL 37538 as part of separating the real runtime package
from the compiler built-in fake runtime package. As of that CL, the
"runtime" package couldn't import any other packages, so this was
adequate at the time.

We could fix this by just changing the implementation of IsRuntimePkg,
but the meaning of this API is clearly somewhat ambiguous. Instead, we
replace it with a new RuntimeSymName function that returns the name of
a symbol if it's in package "runtime", or "" if not. This is what
every call site (except one) actually wants, which lets us simplify
the callers, and also more clearly addresses the ambiguity between
package "runtime" and the general concept of a runtime package.

IsReflectPkg doesn't have the same issue of ambiguity, but it
parallels IsRuntimePkg and is used in the same way, so we replace it
with a new ReflectSymName for consistency.

Change-Id: If3a81d7d11732a9ab2cac9488d17508415cfb597
Reviewed-on: https://go-review.googlesource.com/c/go/+/521696
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-22 19:18:21 +00:00
Michael Anthony Knyszek
9f9bb26880 runtime: avoid MADV_HUGEPAGE for heap memory
Currently the runtime marks all new memory as MADV_HUGEPAGE on Linux and
manages its hugepage eligibility status. Unfortunately, the default
THP behavior on most Linux distros is that MADV_HUGEPAGE blocks while
the kernel eagerly reclaims and compacts memory to allocate a hugepage.

This direct reclaim and compaction is unbounded, and may result in
significant application thread stalls. In really bad cases, this can
exceed 100s of ms or even seconds.

Really all we want is to undo MADV_NOHUGEPAGE marks and let the default
Linux paging behavior take over, but the only way to unmark a region as
MADV_NOHUGEPAGE is to also mark it MADV_HUGEPAGE.

The overall strategy of trying to keep hugepages for the heap unbroken
however is sound. So instead let's use the new shiny MADV_COLLAPSE if it
exists.

MADV_COLLAPSE makes a best-effort synchronous attempt at collapsing the
physical memory backing a memory region into a hugepage. We'll use
MADV_COLLAPSE where we would've used MADV_HUGEPAGE, and stop using
MADV_NOHUGEPAGE altogether.

Because MADV_COLLAPSE is synchronous, it's also important to not
re-collapse huge pages if the huge pages are likely part of some large
allocation. Although in many cases it's advantageous to back these
allocations with hugepages because they're contiguous, eagerly
collapsing every hugepage means having to page in at least part of the
large allocation.

However, because we won't use MADV_NOHUGEPAGE anymore, we'll no longer
handle the fact that khugepaged might come in and back some memory we
returned to the OS with a hugepage. I've come to the conclusion that
this is basically unavoidable without a new madvise flag and that it's
just not a good default. If this change lands, advice about Linux huge
page settings will be added to the GC guide.

Verified that this change doesn't regress Sweet, at least not on my
machine with:

/sys/kernel/mm/transparent_hugepage/enabled [always or madvise]
/sys/kernel/mm/transparent_hugepage/defrag [madvise]
/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none [0 or 511]

Unfortunately, this workaround means that we only get forced hugepages
on Linux 6.1+.

Fixes #61718.

Change-Id: I7f4a7ba397847de29f800a99f9cb66cb2720a533
Reviewed-on: https://go-review.googlesource.com/c/go/+/516795
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
2023-08-22 19:05:10 +00:00
Bryan C. Mills
5dda490372 net/http: use testenv.Command instead of exec.Command in tests
On Unix platforms, testenv.Command sends SIGQUIT to stuck commands
before the test times out. For subprocesses that are written in Go,
that causes the runtime to dump running goroutines, and in other
languages it triggers similar behavior (such as a core dump).
If the subprocess is stuck due to a bug (such as #57999), that may
help to diagnose it.

For #57999.

Change-Id: Ia2e9d14718a26001e030e162c69892497a8ebb21
Reviewed-on: https://go-review.googlesource.com/c/go/+/521816
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
2023-08-22 18:18:19 +00:00
Tobias Klauser
282cd561bb net/netip: remove unused netIPv{4,6}len consts
These were added by CL 339309 but never used.

Change-Id: I40cbb5b18ac94e72bc56c15bb239677de2a202f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/521216
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
2023-08-22 17:28:10 +00:00
Keith Randall
463c34451d cmd/compile: use better line numbers for write barriers
When the write barrier does several pointer writes under one
write barrier flag check, the line numbers aren't really correct.

The writes inside the write barrier have a confusing set of positions.
The loads of the old values are given the line number of the
corresponding store instruction, but the stores into the write buffer
are given the line number of the first store. Instead, give them all
line numbers corresponding to the store instruction.

The writes at the merge point, which are the original writes and the
only ones that happen when the barrier is off, are currently all given
the line number of the first write. Instead give them their original
line number.

Change-Id: Id64820b707f45f07b0978f8d03c97900fdc4bc0b
Reviewed-on: https://go-review.googlesource.com/c/go/+/521499
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
2023-08-22 15:11:33 +00:00
Meng Zhuo
63ab68ddc5 cmd/compile: add single-precision FMA code generation for riscv64
This CL adds FMADDS,FMSUBS,FNMADDS,FNMSUBS SSA support for riscv

Change-Id: I1e7dd322b46b9e0f4923dbba256303d69ed12066
Reviewed-on: https://go-review.googlesource.com/c/go/+/506616
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Run-TryBot: M Zhuo <mzh@golangcn.org>
2023-08-22 12:05:36 +00:00
Meng Zhuo
05f9511582 cmd/compile: improve FP FMA performance on riscv64
FMADD/FMSUB/FNSUB are an efficient FP FMA instructions, which can
be used by the compiler to improve FP performance.

Erf               188.0n ± 2%   139.5n ± 2%  -25.82% (p=0.000 n=10)
Erfc              193.6n ± 1%   143.2n ± 1%  -26.01% (p=0.000 n=10)
Erfinv            244.4n ± 2%   172.6n ± 0%  -29.40% (p=0.000 n=10)
Erfcinv           244.7n ± 2%   173.0n ± 1%  -29.31% (p=0.000 n=10)
geomean           216.0n        156.3n       -27.65%

Ref: The RISC-V Instruction Set Manual Volume I: Unprivileged ISA
11.6 Single-Precision Floating-Point Computational Instructions

Change-Id: I89aa3a4df7576fdd47f4a6ee608ac16feafd093c
Reviewed-on: https://go-review.googlesource.com/c/go/+/506036
Reviewed-by: Joel Sing <joel@sing.id.au>
Run-TryBot: M Zhuo <mzh@golangcn.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-22 08:38:08 +00:00
Joel Sing
e7e99a8e02 syscall: add support for openbsd/ppc64
Add syscall support for the openbsd/ppc64 port.

Updates #56001

Change-Id: I695c5c296e90645515de0c8f89f1bc57e976679d
Reviewed-on: https://go-review.googlesource.com/c/go/+/475636
Reviewed-by: Eric Grosse <grosse@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-22 03:24:15 +00:00
Joel Sing
c140105e1c runtime: add support for openbsd/ppc64
Add runtime support for the openbsd/ppc64 port.

Updates #56001

Change-Id: I3cf010b34f96ce269858b02f16481fdad2cd5b77
Reviewed-on: https://go-review.googlesource.com/c/go/+/475618
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Eric Grosse <grosse@gmail.com>
2023-08-22 02:48:11 +00:00
Joel Sing
b291538d33 runtime: rework asmcgocall on ppc64x
On some platforms asmcgocall can be called with a nil g. Additionally, it
can be called when already on a the system (g0) stack or on a signal stack.
In these cases we do not need to switch (and/or cannot switch) to the
system stack and as a result, do not need to save the g.

Rework asmcgocall on ppc64x to follow the pattern used on other architectures,
such as amd64 and arm64, where a separate nosave path is called in the above
cases. The nil g case will be needed to support openbsd/ppc64.

Updates #56001

Change-Id: I431d4200bcbc4aaddeb617aefe18590165ff2927
Reviewed-on: https://go-review.googlesource.com/c/go/+/478775
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-22 02:47:15 +00:00
Joel Sing
26d4ce70d4 cmd/internal/obj/arm64: add test coverage for VMOVS and VMOVD
Change-Id: I31ba6696e124dccf37d674d090fdf04ba0a049a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/515616
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
2023-08-22 02:46:11 +00:00
Matthew Dempsky
14f5eb7f31 cmd/compile/internal/types: overhaul and simplify API
This CL removes a lot of the redundant methods for accessing struct
fields and signature parameters. In particular, users never have to
write ".Slice()" or ".FieldSlice()" anymore; the exported APIs just do
what you want.

Further internal refactorings to follow.

Change-Id: I45212f6772fe16aad39d0e68b82d71b0796e5639
Reviewed-on: https://go-review.googlesource.com/c/go/+/521295
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
2023-08-22 01:53:41 +00:00
Matthew Dempsky
fecf51717f cmd/compile/internal/walk: reuse runtime.scase
Shaves ~1.5kB off cmd/go binary.

Change-Id: I8ad85aa4a24bc197b009c8e1ea9201957222152a
Reviewed-on: https://go-review.googlesource.com/c/go/+/521677
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
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Reviewed-by: Keith Randall <khr@google.com>
2023-08-21 23:34:34 +00:00
Matthew Dempsky
e7240ed886 cmd/compile/internal/ssagen: share runtime._defer types
Rather than constructing a new runtime._defer struct type at each
defer statement, we can use a single shared one. Also, by naming it
runtime._defer, we avoid emitting new runtime and DWARF type
descriptors in every package that contains a "defer" statement.

Shaves ~1kB off cmd/go.

Change-Id: I0bd819aec9f856546e684abf620e339a7555e73f
Reviewed-on: https://go-review.googlesource.com/c/go/+/521676
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
2023-08-21 23:30:29 +00:00
Matthew Dempsky
42f4ccb6f9 cmd/compile/internal/reflectdata: share hmap and hiter types
There's no need for distinct hmap and hiter types for each map.

Shaves 9kB off cmd/go binary size.

Change-Id: I7bc3b2d8ec82e7fcd78c1cb17733ebd8b615990a
Reviewed-on: https://go-review.googlesource.com/c/go/+/521615
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
2023-08-21 23:29:33 +00:00
Matthew Dempsky
ba6fe5172d spec: clarify that []byte("") must be non-nil
The example text below suggests that []byte("") always evaluates to
the non-nil value []byte{}, but the text proper doesn't explicitly
require that. This CL makes it clear that it must not evaluate to
[]byte(nil), which otherwise was allowed by the wording.

Change-Id: I6564bfd5e2fd0c820d9b55d17406221ff93ce80c
Reviewed-on: https://go-review.googlesource.com/c/go/+/521035
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
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Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
2023-08-21 23:20:08 +00:00
Jes Cok
e3c80f5778 os/exec: don't convert byte slice to string when using verb %s
Change-Id: I4d755e401acf670fb5a154ff59e4e4335ed2138e
GitHub-Last-Rev: a91d74ae55
GitHub-Pull-Request: golang/go#62150
Reviewed-on: https://go-review.googlesource.com/c/go/+/520918
Run-TryBot: Ian Lance Taylor <iant@golang.org>
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Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2023-08-21 23:20:06 +00:00
Mateusz Poliwczak
c513a61988 net: use avoidDNS for search suffixes
The go resolver shouldn't attempt to query .onion domains, but
the restriction was not restricted for search domains.

Also before this change query for "sth.onion" would
not be suffixed with any search domain (for "go.dev" search
domain, it should query fine the "std.onion.go.dev" domain).

Change-Id: I0f3e1387e0d59721381695f94586e3743603c30e
GitHub-Last-Rev: 7e8ec44078
GitHub-Pull-Request: golang/go#60678
Reviewed-on: https://go-review.googlesource.com/c/go/+/501701
Run-TryBot: Mateusz Poliwczak <mpoliwczak34@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
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2023-08-21 23:20:00 +00:00
Matthew Dempsky
4764542034 cmd/compile/internal/compare: simplify unit test framework
This CL refactors the compare unit tests to be simpler and to stop
using the types API in non-idiomatic ways, to facilitate further
refactoring of the API.

Change-Id: I864a66b2842a0d8dd45f4e3d773144d71666caf2
Reviewed-on: https://go-review.googlesource.com/c/go/+/521275
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
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2023-08-21 21:48:32 +00:00
Matthew Dempsky
d5cd55a289 cmd/compile/internal/abi: stop using types.Func
This is supposed to be an internal type within package types. At least
for now, users of the types package should stick to the types.Type
APIs as much as possible.

This CL also unexports FuncType and a few others to prevent
backsliding.

Change-Id: I053fc115a5e6a57c148c8149851a45114756072f
Reviewed-on: https://go-review.googlesource.com/c/go/+/521255
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Austin Clements <austin@google.com>
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2023-08-21 21:44:12 +00:00
Matthew Dempsky
d1593b7a4a cmd/compile: do some TODOs about Fatalf
Separate CL in case I'm mistaken.

Change-Id: I6b5fa0efb27a6b4fb4c133698bd7e2f01b4cccdb
Reviewed-on: https://go-review.googlesource.com/c/go/+/521195
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
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Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
2023-08-21 21:39:33 +00:00
Austin Clements
caf9e15fb7 runtime: drop stack-allocated pcvalueCaches
Now that pcvalue keeps its cache on the M, we can drop all of the
stack-allocated pcvalueCaches and stop carefully passing them around
between lots of operations. This significantly simplifies a fair
amount of code and makes several structures smaller.

This series of changes has no statistically significant effect on any
runtime Stack benchmarks.

I also experimented with making the cache larger, now that the impact
is limited to the M struct, but wasn't able to measure any
improvements.

This is a re-roll of CL 515277

Change-Id: Ia27529302f81c1c92fb9c3a7474739eca80bfca1
Reviewed-on: https://go-review.googlesource.com/c/go/+/520064
Auto-Submit: Austin Clements <austin@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
2023-08-21 21:06:52 +00:00
Austin Clements
4a8373c553 runtime: move pcvalue cache to M
Currently, the pcvalue cache is stack allocated for each operation
that needs to look up a lot of pcvalues. It's not always clear where
to put it, a lot of the time we just pass a nil cache, it doesn't get
reused across operations, and we put a surprising amount of effort
into threading these caches around.

This CL moves it to the M, where it can be long-lived and used by all
pcvalue lookups, and we don't have to carefully thread it across
operations.

This is a re-roll of CL 515276 with a fix for reentrant use of the
pcvalue cache from the signal handler.

Change-Id: Id94c0c0fb3004d1fda1b196790eebd949c621f28
Reviewed-on: https://go-review.googlesource.com/c/go/+/520063
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Auto-Submit: Austin Clements <austin@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
2023-08-21 21:05:54 +00:00
Keith Randall
0b47b94a62 cmd/compile: remove more extension ops when not needed
If we're not using the upper bits, don't bother issuing a
sign/zero extension operation.

For arm64, after CL 520916 which fixed a correctness bug with
extensions but as a side effect leaves many unnecessary ones
still in place.

Change-Id: I5f4fe4efbf2e9f80969ab5b9a6122fb812dc2ec0
Reviewed-on: https://go-review.googlesource.com/c/go/+/521496
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-21 20:52:15 +00:00
Keith Randall
a9bedc36a5 cmd/compile: ensure we keep top 32 bits zeroed for 32-bit arm64 ops
When rewriting, for example, MSUBW, we need to ensure that the result
has its 32 top bits zeroed. That's what the instruction is spec'd to do.
Normally, we'd only use MSUBW for computations on 32-bit values, and
as such the top 32 bits aren't normally used. But some situations, like
if we cast the result to a uint64, the top 32 bits do matter.

This comes up in 62131 because we have a rule saying, MOVWUreg applied
to a MSUBW is unnecessary, as the arg to MOVWUreg already has zeroed
top 32 bits. But if MSUBW is later rewritten to another op that doesn't
zero the top 32 bits (SUB, probably), getting rid of the MOVWUreg earlier
causes a problem.

So change rewrite rules to always maintain the top 32 bits as zero if the
instruction is spec'd to provide that. We need to introduce a few *W operations
to make that happen.

Fixes #62131

Change-Id: If3d160821e285fd7454746b735a243671bff8894
Reviewed-on: https://go-review.googlesource.com/c/go/+/520916
Run-TryBot: Keith Randall <khr@golang.org>
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Reviewed-by: Keith Randall <khr@google.com>
2023-08-21 20:51:49 +00:00
Bryan C. Mills
1081f8c058 context: fix synchronization in ExampleAfterFunc_cond
Condition variables are subtle and error-prone, and this example
demonstrates exactly the sorts of problems that they introduce.
Unfortunately, we're stuck with them for the foreseeable future.

As previously implemented, this example was racy: since the callback
passed to context.AfterFunc did not lock the mutex before calling
Broadcast, it was possible for the Broadcast to occur before the
goroutine was parked in the call to Wait, causing in a missed wakeup
resulting in deadlock.

The example also had a more insidious problem: it was not safe for
multiple goroutines to call waitOnCond concurrently, but the whole
point of using a sync.Cond is generally to synchronize concurrent
goroutines. waitOnCond must use Broadcast to ensure that it wakes up
the target goroutine, but the use of Broadcast in this way would
produce spurious wakeups for all of the other goroutines waiting on
the same condition variable. Since waitOnCond did not recheck the
condition in a loop, those spurious wakeups would cause waitOnCond
to spuriously return even if its own ctx was not yet done.

Fixing the aforementioned bugs exposes a final problem, inherent to
the use of condition variables in this way. This one is a performance
problem: for N concurrent calls to waitOnCond, the resulting CPU cost
is at least O(N²). This problem cannot be addressed without either
reintroducing one of the above bugs or abandoning sync.Cond in the
example entirely. Given that this example was already published in Go
1.21, I worry that Go users may think that it is appropriate to use a
sync.Cond in conjunction with context.AfterFunc, so I have chosen to
retain the Cond-based example and document its pitfalls instead of
removing or replacing it entirely.

I described this class of bugs and performance issues — and suggested
some channel-based alternatives — in my GopherCon 2018 talk,
“Rethinking Classical Concurrency Patterns”. The section on condition
variables starts on slide 37. (https://youtu.be/5zXAHh5tJqQ?t=679)

Fixes #62180.
For #20491.

Change-Id: If987cd9d112997c56171a7ef4fccadb360bb79bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/521596
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
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2023-08-21 20:24:28 +00:00
Bryan C. Mills
9e9556d328 cmd/go: find GOROOT using os.Executable when installed to GOROOT/bin/GOOS_GOARCH
When running make.bash in a cross-compiled configuration
(for example, GOARCH different from GOHOSTARCH), cmd/go
is installed to GOROOT/bin/GOOS_GOARCH instead of GOROOT/bin.

That means that we need to look for GOROOT in both ../.. and ../../..,
not just the former.

Fixes #62119.
Updates #18678.

Change-Id: I283c6a10c46df573ff44da826f870417359226a7
Reviewed-on: https://go-review.googlesource.com/c/go/+/521015
Reviewed-by: Michael Matloob <matloob@golang.org>
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2023-08-21 20:24:22 +00:00
Austin Clements
e7a1eb066b cmd/compile: move racewalk comment to walk/race.go
This comment got left behind in some refactoring and now refers to
code "below" that is no longer below. Move it to be with the code it's
referring to.

Change-Id: I7f7bf0cf8b22c1f6e05ff12b8be71d18fb3359d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/521177
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Auto-Submit: Austin Clements <austin@google.com>
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2023-08-21 20:20:03 +00:00
Austin Clements
01cad815a1 runtime: remove runtime.Add testing function
Replace with unsafe.Add.

Change-Id: Ic5c155349dadc51457119b3c05ab717cdfd26c95
Reviewed-on: https://go-review.googlesource.com/c/go/+/521176
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2023-08-21 20:20:01 +00:00
Alexander Yastrebov
38a0c5bdb4 net/http: clear reference to the request context after transport getConn
Clears wannConn ctx and prevents pending dialConnFor after connection delivered or canceled.

Updates #50798

Change-Id: I9a681ac0f222be56571fa768700220f6b5ee0888
GitHub-Last-Rev: fd6c83ab07
GitHub-Pull-Request: golang/go#61524
Reviewed-on: https://go-review.googlesource.com/c/go/+/512196
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2023-08-21 20:17:03 +00:00
Alexander Yastrebov
c738344171 net/http: use cancelKey to cancel request
Follows up on CL 245357 and adds missing returns in waitCondition (CL 477196)

Fixes #51354

Change-Id: I7950ff889ad72c4927a969c35fedc0186e863bd6
GitHub-Last-Rev: 52ce05bc83
GitHub-Pull-Request: golang/go#61724
Reviewed-on: https://go-review.googlesource.com/c/go/+/515435
Reviewed-by: Damien Neil <dneil@google.com>
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2023-08-21 18:00:29 +00:00
Josh Kraft
e4a8fb0fa0 os: add tests for UserCacheDir and UserConfigDir
Adds basic test scenarios for UserCacheDir and
UserConfigDir.

Fixes #57638

Change-Id: Ieb86e95faff44287bfa13daa0cb26e7b5401373b
Reviewed-on: https://go-review.googlesource.com/c/go/+/520262
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2023-08-21 17:46:57 +00:00
Andy Pan
a7c3de7052 runtime: document maxStack and m.createstack in more details
Change-Id: If93b6cfa5a598a5f4101c879a0cd88a194e4a6aa
Reviewed-on: https://go-review.googlesource.com/c/go/+/518116
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2023-08-21 17:10:00 +00:00
qmuntal
50f2b7b764 os: avoid allocating a string for ReadDir skipped entries on Windows
Shave off a few allocations while reading a directory by checking
if the entry name is "." or ".." before allocating a string for it.

Change-Id: I05a87d7572bd4fc191db70aaa9e22a6102f68b4b
Reviewed-on: https://go-review.googlesource.com/c/go/+/520415
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2023-08-21 08:33:51 +00:00
Austin Clements
e094e80f65 runtime: add self-check mode to cache in pcvalue
This would have helped with debugging the failures caused by CL 515276.

Change-Id: Id641949d8bcd763de7f93778ad9bd3fdde95dcb2
Reviewed-on: https://go-review.googlesource.com/c/go/+/520062
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2023-08-20 17:52:59 +00:00
Matthew Dempsky
9ac6b00e79 cmd/compile/internal/typecheck: add selector helpers
This CL refactors common patterns for constructing field and method
selector expressions. Notably, XDotField and XDotMethod are now the
only two functions where a SelecterExpr with OXDOT is constructed.

Change-Id: I4c087225d8b295c4a6a92281ffcbcabafe2dc94d
Reviewed-on: https://go-review.googlesource.com/c/go/+/520979
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2023-08-20 05:57:18 +00:00
Matthew Dempsky
3761e3fbfd cmd/compile/internal/typecheck: simplify NewMethodExpr
This CL changes NewMethodExpr to directly construct the OMETHEXPR
node, instead of running through the generic OXDOT typechecking
machinery.

Change-Id: Ic2af0bab6ff1aef45e8463bccb1f69c50db68f65
Reviewed-on: https://go-review.googlesource.com/c/go/+/520919
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2023-08-20 05:57:15 +00:00
Matthew Dempsky
a2ec545e0a cmd/compile/internal/typecheck: add NewMethodExpr helper
This CL refactors the common pattern for constructing OMETHEXPR nodes,
which is the most common use of ir.TypeNode currently.

Change-Id: I446a21af97ab5a4bc2f04bbd581c1ede8a5ede60
Reviewed-on: https://go-review.googlesource.com/c/go/+/520978
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2023-08-20 05:56:51 +00:00
Matthew Dempsky
009ca22fe2 cmd/compile/internal/typecheck: refactor and simplify DeclFunc
This CL refactors typecheck.DeclFunc to require the caller to have
already constructed the ir.Func and signature type using ir.NewFunc
and types.NewSignature, and simplifies typecheck.DeclFunc to simply
return the slices of param and results ONAMEs.

typecheck.DeclFunc was the last reason that ir.Field still exists, so
this CL also gets rid of that.

Change-Id: Ib398420bac2fd135a235810b8af1635fa754965c
Reviewed-on: https://go-review.googlesource.com/c/go/+/520977
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2023-08-20 05:56:49 +00:00
Brad Fitzpatrick
b581e44739 slices: simplify Clone a bit
No need for an explicit nil check. Slicing the input slice
down to zero capacity also preserves nil.

Change-Id: I1f53cc485373d0e65971cd87b6243650ac72612c
Reviewed-on: https://go-review.googlesource.com/c/go/+/521037
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2023-08-20 04:12:09 +00:00
Mateusz Poliwczak
0b6ea6bb04 net: return "cannot unmarshal" error while parsing DNS messages
Change-Id: I407f5d3d3a3e8b3d43ff154f731d885e831971e9
GitHub-Last-Rev: d6a400d1ba
GitHub-Pull-Request: golang/go#62155
Reviewed-on: https://go-review.googlesource.com/c/go/+/520980
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2023-08-19 23:35:39 +00:00
Dmitri Shuralyov
69285cd778 cmd/compile/internal/gc: remove unused reflectdata import
CL 521036 was prepared and tested before the revert CL 521155,
and it so happens that the reflectdata import ended up unused.
Drop it to fix the build.

Change-Id: I230c8fee616fc58cc82f3e5da886bcee2e02a3d3
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2023-08-19 23:35:09 +00:00
Joe Tsai
81d9214ff6 expvar: emit valid JSON strings
Map.String and expvarHandler used the %q flag with fmt.Fprintf
to escape Go strings, which does so according to the Go grammar,
which is not always compatible with JSON strings.

Rather than calling json.Marshal for every string,
which will always allocate, declare a local appendJSONQuote
function that does basic string escaping.
Also, we declare an unexported appendJSON method on every
concrete Var type so that the final JSON output can be
constructed with far fewer allocations.

The resulting logic is both more correct and also much faster.
This does not alter the whitespace style of Map.String or expvarHandler,
but may alter the representation of JSON strings.

Performance:

	name         old time/op    new time/op    delta
	MapString    5.10µs ± 1%    1.56µs ± 1%  -69.33%  (p=0.000 n=10+9)

	name         old alloc/op   new alloc/op   delta
	MapString    1.21kB ± 0%    0.66kB ± 0%  -45.12%  (p=0.000 n=10+10)

	name         old allocs/op  new allocs/op  delta
	MapString      37.0 ± 0%       7.0 ± 0%  -81.08%  (p=0.000 n=10+10)

Fixes #59040

Change-Id: I46a2125f43550b91d52019e5edc003d9dd19590f
Reviewed-on: https://go-review.googlesource.com/c/go/+/476336
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2023-08-19 23:26:49 +00:00
Ian Lance Taylor
e019d01d98 encoding/csv: correct Column docs
For #44221
Fixes #62147

Change-Id: Ibcc0d11c8253f51a8f5771791ea4173a38a61950
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2023-08-19 23:05:33 +00:00
Andy Pan
ba626ac327 encoding/gob: prevent panic from index out of range in Decoder.typeString
I believe this bug is introduced by CL 460543 which optimizes the allocations
by changing the type of `idToType` from map to slice, but didn't update the
access code in `Decoder.typeString` that is safe for map but not for slice.

Fixes #62117

Change-Id: I0f2e4cc2f34c54dada1f83458ba512a6fde6dcbe
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2023-08-19 23:03:14 +00:00
Matthew Dempsky
7b2f81eb3b cmd/compile/internal/typecheck: remove NeedRuntimeType
The only remaining use for typecheck.NeedRuntimeType is to make sure
that method expressions with anonymous receiver types (e.g.,
"struct{T}.M") have the promoted-method wrapper generated. But the
unified frontend takes care of arranging for this now.

Change-Id: I89340cb6a81343f35e0de1062610cbb993d3b6bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/521036
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2023-08-19 22:40:55 +00:00
Joe Tsai
e8cdab5c49 encoding: optimize growth behavior in Encoding.AppendDecode
The Encoding.DecodedLen API only returns the maximum length of the
expected decoded output, since it does not know about padding.
Since we have the input, we can do better by computing the
input length without padding, and then perform the DecodedLen
calculation as if there were no padding.

This avoids over-growing the destination slice if possible.
Over-growth is still possible since the input may contain
ignore characters like newlines and carriage returns,
but those a rarely encountered in practice.

Change-Id: I38b8f91de1f4fbd3a7128c491a25098bd385cf74
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2023-08-19 22:25:23 +00:00
Matthew Dempsky
e47fad515d Revert "cmd/compile/internal/gc: steps towards work-queue"
This reverts commit CL 520611.

Reason for revert: #62156.

Change-Id: Iebd17bdfc00824de3d5011a74d071a41c4fa06f1
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2023-08-19 22:20:28 +00:00