An ETXTBSY error when starting a test binary is almost certainly
caused by the race reported in #22315. That race will resolve quickly
on its own, so we should just retry the command instead of reporting a
spurious failure.
Fixes#62221.
Change-Id: I408f3eaa7ab5d7efbc7a2b1c8bea3dbc459fc794
Reviewed-on: https://go-review.googlesource.com/c/go/+/522015
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Change-Id: Ia63a4604449b5e460e6f54c962fb7d6db2bc6a43
Reviewed-on: https://go-review.googlesource.com/c/go/+/519457
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
In checking whether a type implements an interface, there's this
complex predicate spanning multiple lines, which is very obtuse.
So let's just use the helper function we already have in package types
instead.
Change-Id: I80f69d41c2bee8d6807601cf913840fa4f042b5e
Reviewed-on: https://go-review.googlesource.com/c/go/+/521435
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
LookupRuntime is the only reason for using SubstArgTypes, and most
callers to LookupRuntime need to immediately call it anyway. So might
as well fuse them together.
Change-Id: Ie0724ed164b949040e898a2a77bea632801b64fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/521415
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Make more use of RecvParams and RecvParamsResults helper methods.
Also, correct misuse of Go spec terminology ("return" is a statement;
"result" is the class of parameters that appear in a function type).
Change-Id: I94807a747c494c9daa5441da7d9e3aea77aae33b
Reviewed-on: https://go-review.googlesource.com/c/go/+/521395
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
The types.RecvsParamsResults, etc. helpers existed to make it "easier"
to iterate over all parameters, or recvs+params, or params+results;
but they end up still being quite clumsy to use due to the design goal
of not allocating temporary slices.
Now that recvs+params+results are stored in a single consecutive slice
anyway, we can just return different subslices and simplify the loops.
Change-Id: I84791b80dc099dfbfbbe6eddbc006135528c23b4
Reviewed-on: https://go-review.googlesource.com/c/go/+/521375
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Now that all of the uses of signature types have been cleaned up, we
can simplify the internal representation significantly.
In particular, instead of 3 separate struct objects each with 3
separate slices of fields, we can store all of the parameters in a
single slice and track the boundaries between them.
We still need a results tuple struct for representing the type of
multi-value call expressions, but just a single one and it can safely
reuse the results subsection of the full parameters slice.
Note: while Sizeof(Func) has increased (e.g., 32->56 on amd64), we're
saving on the allocation of 2 Types, 2 Structs, and 2 []*Field (288
bytes total on amd64), not counting any extra GC size class padding
from using a single shared []*Field instead of 3 separate ones.
Change-Id: I119b5e960e715b3bc4f1f726e58b910a098659da
Reviewed-on: https://go-review.googlesource.com/c/go/+/521335
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
TryBot-Bypass: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
We already have a magic constant to represent fields that haven't had
their offsets calculated. We don't need two.
Change-Id: Ibfa95a3a15a5cd43e1e5ec7d0971d3e61d47fb3c
Reviewed-on: https://go-review.googlesource.com/c/go/+/521317
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
This CL changes the pretty printer to not rely on parameter lists
being represented as TSTRUCTs.
Change-Id: Ie2b8192ee07b96ffbe224e5d98a335368f47abc2
Reviewed-on: https://go-review.googlesource.com/c/go/+/521316
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
There's no need for the Funarg type anymore. A simple boolean suffices
to indicate whether a TSTRUCT represents a parameter tuple.
While here, rename Struct.Funarg to ParamTuple.
Change-Id: I657512d4ba10e51ec4cfd7c7d77e0194bdb0853b
Reviewed-on: https://go-review.googlesource.com/c/go/+/521315
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
This CL simplifies how struct sizes and field offsets are calculated.
Change-Id: If4af778cb49218d295277df596e45bdd8b23ed9d
Reviewed-on: https://go-review.googlesource.com/c/go/+/521276
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This consolidates the NoInstrumentPkgs and NoRacePkgs lists into the
objabi.LookupPkgSpecial mechanism.
Change-Id: I411654afdd690fb01c412e7e8b57ddfbe85415e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/521702
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Austin Clements <austin@google.com>
Currently, this list includes *almost* all runtime packages, but not
quite all.
We leave out internal/bytealg for reasons explained in the code.
Compiling with or without race instrumentation has no effect on the
other packages added to the list here, so this is a no-op change
today, but makes this more robust.
Change-Id: Iaec585b2efbc72983d8cb3929394524c42dd664d
Reviewed-on: https://go-review.googlesource.com/c/go/+/521701
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This adds a test that all packages imported by runtime are marked as
runtime tests by LookupPkgSpecial. We add two packages that were
missing from the list.
Change-Id: I2545980ab09474de0181cf546541527d8baaf2e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/521700
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
As we did for the asm -compiling-runtime flag, this CL modifies the
compiler to compute the -+ (compiling runtime) flag from the package
path. Unlike for asm, some tests use -+ explicitly to opt in to
runtime restrictions, so we leave the flag, but it's no longer passed
by any build tools.
This lets us eliminate cmd/go's list of "runtime packages" in favor of
the unified objabi.LookupPkgSpecial. It also fixes an inconsistency
with dist, which only passed -+ when compiling "runtime" itself.
One consequence of this is that the compiler now ignores the -N flag
when compiling runtime packages. Previously, cmd/go would strip -N
when passing -+ and the compiler would fatal if it got both -N and -+,
so the overall effect was that the compiler never saw -N when
compiling a runtime package. Now we simply move that logic to disable
-N down into the compiler.
Change-Id: I4876047a1563210ed122a31b72d62798762cbcf5
Reviewed-on: https://go-review.googlesource.com/c/go/+/521699
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
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>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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>
TryBot-Result: Gopher Robot <gobot@golang.org>
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>
TryBot-Result: Gopher Robot <gobot@golang.org>
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>
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>
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>
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>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@google.com>
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>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
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>
Auto-Submit: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
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
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Austin Clements <austin@google.com>
TryBot-Bypass: Austin Clements <austin@google.com>
