When a non-Go thread calls into Go, the runtime needs an M to run the Go
code. The runtime keeps a list of extra M's available. When the last
extra M is allocated, the needextram field is set to tell it to allocate
a new extra M as soon as it is running in Go. This ensures that an extra
M will always be available for the next thread.
However, if many threads need an extra M at the same time, this
serializes them all. One thread will get an extra M with the needextram
field set. All the other threads will see that there is no M available
and will go to sleep. The one thread that succeeded will create a new
extra M. One lucky thread will get it. All the other threads will see
that there is no M available and will go to sleep. The effect is
thundering herd, as all the threads looking for an extra M go through
the process one by one. This seems to have a particularly bad effect on
the FreeBSD scheduler for some reason.
With this change, we track the number of threads waiting for an M, and
create all of them as soon as one thread gets through. This still means
that all the threads will fight for the lock to pick up the next M. But
at least each thread that gets the lock will succeed, instead of going
to sleep only to fight again.
This smooths out the performance greatly on FreeBSD, reducing the
average wall time of `testprogcgo CgoCallbackGC` by 74%. On GNU/Linux
the average wall time goes down by 9%.
Fixes#13926Fixes#16396
Change-Id: I6dc42a4156085a7ed4e5334c60b39db8f8ef8fea
Reviewed-on: https://go-review.googlesource.com/25047
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
This copies the frozen wording from the log/syslog package.
Fixes#16436
Change-Id: If5d478023328925299399f228d8aaf7fb117c1b4
Reviewed-on: https://go-review.googlesource.com/25080
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
Fix up zero/move code, including duff calls and rep movs.
Handle the new ops generated by dec64.rules.
Fix constant shifts.
Change-Id: I7d89194b29b04311bfafa0fd93b9f5644af04df9
Reviewed-on: https://go-review.googlesource.com/25033
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Rather than saying "stop-the-world", say "garbage collection pauses".
Change-Id: Ifb2931781ab3094e04bea93f01f18f1acb889bdc
Reviewed-on: https://go-review.googlesource.com/25018
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
We now allow Values to have 2 outputs. Use that ability for amd64.
This allows x,y := a/b,a%b to use just a single divide instruction.
Update #6815
Change-Id: Id70bcd20188a2dd8445e631a11d11f60991921e4
Reviewed-on: https://go-review.googlesource.com/25004
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
Make tuple types and their SelectX ops fully generic.
These ops no longer need to be lowered.
Regalloc understands them and their tuple-generating arguments.
We can now have opcodes returning arbitrary pairs of results.
(And it would be easy to move to >2 results if needed.)
Update arm implementation to the new standard.
Implement just enough in 386 port to do 64-bit add.
Change-Id: I370ed5aacce219c82e1954c61d1f63af76c16f79
Reviewed-on: https://go-review.googlesource.com/24976
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Because,
* The CGI spec defines that incoming request header "Foo: Bar" maps to
environment variable HTTP_FOO == "Bar". (see RFC 3875 4.1.18)
* The HTTP_PROXY environment variable is conventionally used to configure
the HTTP proxy for HTTP clients (and is respected by default for
Go's net/http.Client and Transport)
That means Go programs running in a CGI environment (as a child
process under a CGI host) are vulnerable to an incoming request
containing "Proxy: attacker.com:1234", setting HTTP_PROXY, and
changing where Go by default proxies all outbound HTTP requests.
This is CVE-2016-5386, aka https://httpoxy.org/Fixes#16405
Change-Id: I6f68ade85421b4807785799f6d98a8b077e871f0
Reviewed-on: https://go-review.googlesource.com/25010
Run-TryBot: Chris Broadfoot <cbro@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Reviewed-on: https://go-review.googlesource.com/25013
Because,
* The CGI spec defines that incoming request header "Foo: Bar" maps to
environment variable HTTP_FOO == "Bar". (see RFC 3875 4.1.18)
* The HTTP_PROXY environment variable is conventionally used to configure
the HTTP proxy for HTTP clients (and is respected by default for
Go's net/http.Client and Transport)
That means Go programs running in a CGI environment (as a child
process under a CGI host) are vulnerable to an incoming request
containing "Proxy: attacker.com:1234", setting HTTP_PROXY, and
changing where Go by default proxies all outbound HTTP requests.
This is CVE-2016-5386, aka https://httpoxy.org/Fixes#16405
Change-Id: I6f68ade85421b4807785799f6d98a8b077e871f0
Reviewed-on: https://go-review.googlesource.com/25010
Run-TryBot: Chris Broadfoot <cbro@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Most of the runtime improvements are hard to quantify or summarize,
but it's worth mentioning some of the substantial improvements in STW
time, and that the scavenger now actually works on ARM64, PPC64, and
MIPS.
Change-Id: I0e951038516378cc3f95b364716ef1c183f3445a
Reviewed-on: https://go-review.googlesource.com/24966
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Only run TestDialerDualStack on the builders, as to not annoy or
otherwise distract users when it's not their fault.
Even though the intention is to only run this on the builders, very
few of the builders have IPv6 support. Oh well. We'll get some
coverage.
Updates #13324
Change-Id: I13e7e3bca77ac990d290cabec88984cc3d24fb67
Reviewed-on: https://go-review.googlesource.com/24985
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
Change https://golang.org/cl/19895 caused a regression
where the last character in a string would be dropped if it was
accompanied by an io.EOF.
This change fixes the logic so that the last byte is still returned
without a problem.
Fixes#16393
Change-Id: I7a4d0abf761c2c15454136a79e065fe002d736ea
Reviewed-on: https://go-review.googlesource.com/24981
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
NaCl code runs in sandbox and there are restrictions for its
instruction uses
(https://developer.chrome.com/native-client/reference/sandbox_internals/arm-32-bit-sandbox).
Like the legacy backend, on NaCl,
- don't use R9, which is used as NaCl's "thread pointer".
- don't use Duff's device.
- don't use indexed load/stores.
- the assembler rewrites DIV/MOD to runtime calls, which on NaCl
clobbers R12, so R12 is marked as clobbered for DIV/MOD.
- other restrictions are satisfied by the assembler.
Enable SSA specific tests on nacl/arm, and disable non-SSA ones.
Updates #15365.
Change-Id: I9262693ec6756b89ca29d3ae4e52a96fe5403b02
Reviewed-on: https://go-review.googlesource.com/24859
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Add some simplification rules for floating point ops.
cmd/internal/obj/arm supports instructions that compare FP register
to 0, but runtime softfloat simulator does not. This CL adds these
instructions to softfloat simulator as well.
Updates #15365.
Change-Id: I29405b2bfcb4c8cf106cb7a1a811409fec91b170
Reviewed-on: https://go-review.googlesource.com/24790
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
We decided that ppc64 should maintain power5 compatibility.
ppc64le requires power8.
Fixes#16372.
Change-Id: If5b309a0563f55a3c1fe9c853d29a463f5b71101
Reviewed-on: https://go-review.googlesource.com/24915
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
If a spill is used to satisfy a merge edge (in shuffle), don't sink
it out of loop.
This is found in the following code (on ARM) where there is a stack
Phi (v268) inside a loop (b36 -> ... -> b47 -> b38 -> b36).
(before shuffle)
b36: <- b34 b38
...
v268 = Phi <int> v410 v360 : autotmp_198[int]
...
... -> b47
b47: <- b44
...
v360 = ... : R6
v230 = StoreReg <int> v360 : autotmp_198[int]
v261 = CMPconst <flags> [0] v360
EQ v261 -> b49 b38 (unlikely)
b38: <- b47
...
Plain -> b36
During shuffle, v230 (as spill of v360) is found to satisfy v268, but
it didn't record its use in shuffle, and v230 is sunk out of the loop
(to b49), which leads to bad value in v268.
This seems never happened on AMD64 (in make.bash), until 4 registers
are removed.
Change-Id: I01dfc28ae461e853b36977c58bcfc0669e556660
Reviewed-on: https://go-review.googlesource.com/24858
Reviewed-by: David Chase <drchase@google.com>
This CL implements the following optimizations for ARM:
- use shifted ops (e.g. ADD R1<<2, R2) and indexed load/stores
- break up shift ops. Shifts used to be one SSA op that generates
multiple instructions. We break them up to multiple ops, which
allows constant folding and CSE for comparisons. Conditional moves
are introduced for this.
- simplify zero/sign-extension ops.
Updates #15365.
Change-Id: I55e262a776a7ef2a1505d75e04d1208913c35d39
Reviewed-on: https://go-review.googlesource.com/24512
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Basically just copied all the amd64 files, removed all the *Q ops,
and rebuilt.
Compiles fib successfully.
Still need to do:
- all the 64->32 bit op translations.
- audit for instructions that aren't available on 386.
- GO386=387?
Update #16358
Change-Id: Ib8c684586416a554a527a5eefa0cff71424e36f5
Reviewed-on: https://go-review.googlesource.com/24912
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This fixes erroneous handling of the more result parameter of
runtime.Frames.Next.
Fixes#16349.
Change-Id: I4f1c0263dafbb883294b31dbb8922b9d3e650200
Reviewed-on: https://go-review.googlesource.com/24911
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Regression from Go 1.6 to Go 1.7rc1: we had broken the ability for
users to vendor "golang.org/x/net/http2" or "golang.org/x/net/route"
because we were vendoring them ourselves and cmd/go and cmd/compile do
not understand multiple vendor directories across multiple GOPATH
workspaces (e.g. user's $GOPATH and default $GOROOT).
As a short-term fix, since fixing cmd/go and cmd/compile is too
invasive at this point in the cycle, just rename "golang.org" to
"golang_org" for the standard library's vendored copy.
Fixes#16333
Change-Id: I9bfaed91e9f7d4ca6bab07befe80d71d437a21af
Reviewed-on: https://go-review.googlesource.com/24902
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Document that the http.Server is now stricter about rejecting
requests with invalid HTTP versions, and also that it rejects plaintext
HTTP/2 requests, except for `PRI * HTTP/2.0` upgrade requests.
The relevant CL is https://golang.org/cl/24505.
Updates #15810.
Change-Id: Ibbace23e001b5e2eee053bd341de50f9b6d3fde8
Reviewed-on: https://go-review.googlesource.com/24731
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
New Gophers sometimes misconstrue the advice in the "Generality" section
as "export interfaces instead of implementations" and add needless
interfaces to their code as a result. Down the road, they end up
needing to add methods and either break existing callers or have to
resort to unpleasant hacks (e.g. using "magic method" type-switches).
Weaken the first paragraph of this section to only advise leaving types
unexported when they will never need additional methods.
Change-Id: I32a1ae44012b5896faf167c02e192398a4dfc0b8
Reviewed-on: https://go-review.googlesource.com/24892
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
Fixes#12272
Change-Id: I0306ce0ef4a87df2158df3b7d4d8d93a1cb6dabc
Reviewed-on: https://go-review.googlesource.com/24864
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
The cgocallback function picked up a ctxt parameter in CL 22508.
That CL updated the assembler implementation, but there are a few
mentions in Go code that were not updated. This CL fixes that.
Fixes#16326
Change-Id: I5f68e23565c6a0b11057aff476d13990bff54a66
Reviewed-on: https://go-review.googlesource.com/24848
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
The reflect package was returning a non-empty PkgPath for an unnamed
type with methods, such as a type whose methods have a pointer
receiver.
Fixes#16328.
Change-Id: I733e93981ebb5c5c108ef9b03bf5494930b93cf3
Reviewed-on: https://go-review.googlesource.com/24862
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This is a copy of the "FANOUT" benchmark recently added to RE2 with the
following comment:
// This has quite a high degree of fanout.
// NFA execution will be particularly slow.
Most of the benchmarks on the regexp package have very little fanout and
are designed for comparing the regexp package's NFA with backtracking
engines found in other regular expression libraries. This benchmark
exercises the performance of the NFA on expressions with high fanout.Reviewed-on: https://go-review.googlesource.com/24846
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
"
This reverts commit fc803874d3.
Reason for revert: Breaks the -race build because the benchmark takes too long to run.
Change-Id: I6ed4b466f74a4108d8bcd5b019b9abe971eb483e
Reviewed-on: https://go-review.googlesource.com/24861
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
This is a copy of the "FANOUT" benchmark recently added to RE2 with the
following comment:
// This has quite a high degree of fanout.
// NFA execution will be particularly slow.
Most of the benchmarks on the regexp package have very little fanout and
are designed for comparing the regexp package's NFA with backtracking
engines found in other regular expression libraries. This benchmark
exercises the performance of the NFA on expressions with high fanout.
Change-Id: Ie9c8e3bbeffeb1fe9fb90474ddd19e53f2f57a52
Reviewed-on: https://go-review.googlesource.com/24846
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
A follow-on to https://golang.org/cl/24852 that mentions the
documentation clarifications.
Updates #16308.
Change-Id: Ic2a6e1d4938d74352f93a6649021fb610efbfcd0
Reviewed-on: https://go-review.googlesource.com/24857
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
There are no synchronization points protecting the readVal and readPos
variables. This leads to a race when Read is called concurrently.
Fix this by adding methods to lockedSource, which is the case where
a race matters.
Fixes#16308.
Change-Id: Ic028909955700906b2d71e5c37c02da21b0f4ad9
Reviewed-on: https://go-review.googlesource.com/24852
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
For better or for worse, it's IsExist, not IsExists.
Change-Id: I4503f961486edd459c0c81cf3f32047dff7703a4
Reviewed-on: https://go-review.googlesource.com/24819
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In the beta version of the macOS Sierra (10.12) release, the
gettimeofday system call changed on x86. Previously it always returned
the time in the AX/DX registers. Now, if AX is returned as 0, it means
that the system call has stored the values into the memory pointed to by
the first argument, just as the libc gettimeofday function does. The
libc function handles both cases, and we need to do so as well.
Fixes#16272.
Change-Id: Ibe5ad50a2c5b125e92b5a4e787db4b5179f6b723
Reviewed-on: https://go-review.googlesource.com/24812
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-on: https://go-review.googlesource.com/24755
Reviewed-by: Chris Broadfoot <cbro@golang.org>
In the beta version of the macOS Sierra (10.12) release, the
gettimeofday system call changed on x86. Previously it always returned
the time in the AX/DX registers. Now, if AX is returned as 0, it means
that the system call has stored the values into the memory pointed to by
the first argument, just as the libc gettimeofday function does. The
libc function handles both cases, and we need to do so as well.
Fixes#16272.
Change-Id: Ibe5ad50a2c5b125e92b5a4e787db4b5179f6b723
Reviewed-on: https://go-review.googlesource.com/24812
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
The shrinkstack code locks all the channels a goroutine is waiting for,
but didn't handle the case of the same channel appearing in the list
multiple times. This led to a deadlock. The channels are sorted so it's
easy to avoid locking the same channel twice.
Fixes#16286.
Change-Id: Ie514805d0532f61c942e85af5b7b8ac405e2ff65
Reviewed-on: https://go-review.googlesource.com/24815
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
