This optimizes deferproc and deferreturn in various ways.
The most important optimization is that it more carefully arranges to
prevent preemption or stack growth. Currently we do this by switching
to the system stack on every deferproc and every deferreturn. While we
need to be on the system stack for the slow path of allocating and
freeing defers, in the common case we can fit in the nosplit stack.
Hence, this change pushes the system stack switch down into the slow
paths and makes everything now exposed to the user stack nosplit. This
also eliminates the need for various acquirem/releasem pairs, since we
are now preventing preemption by preventing stack split checks.
As another smaller optimization, we special case the common cases of
zero-sized and pointer-sized defer frames to respectively skip the
copy and perform the copy in line instead of calling memmove.
This speeds up the runtime defer benchmark by 42%:
name old time/op new time/op delta
Defer-4 75.1ns ± 1% 43.3ns ± 1% -42.31% (p=0.000 n=8+10)
In reality, this speeds up defer by about 2.2X. The two benchmarks
below compare a Lock/defer Unlock pair (DeferLock) with a Lock/Unlock
pair (NoDeferLock). NoDeferLock establishes a baseline cost, so these
two benchmarks together show that this change reduces the overhead of
defer from 61.4ns to 27.9ns.
name old time/op new time/op delta
DeferLock-4 77.4ns ± 1% 43.9ns ± 1% -43.31% (p=0.000 n=10+10)
NoDeferLock-4 16.0ns ± 0% 15.9ns ± 0% -0.39% (p=0.000 n=9+8)
This also shaves 34ns off cgo calls:
name old time/op new time/op delta
CgoNoop-4 122ns ± 1% 88.3ns ± 1% -27.72% (p=0.000 n=8+9)
Updates #14939, #16051.
Change-Id: I2baa0dea378b7e4efebbee8fca919a97d5e15f38
Reviewed-on: https://go-review.googlesource.com/29656
Reviewed-by: Keith Randall <khr@golang.org>
This makes it possible to inline getcallersp. getcallersp is on the
hot path of defers, so this slightly speeds up defer:
name old time/op new time/op delta
Defer-4 78.3ns ± 2% 75.1ns ± 1% -4.00% (p=0.000 n=9+8)
Updates #14939.
Change-Id: Icc1cc4cd2f0a81fc4c8344432d0b2e783accacdd
Reviewed-on: https://go-review.googlesource.com/29655
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
The big documentation comment at the top of malloc.go has gotten
woefully out of date. Update it.
Change-Id: Ibdb1bdcfdd707a6dc9db79d0633a36a28882301b
Reviewed-on: https://go-review.googlesource.com/29731
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
This documents all fields in MemStats and more clearly documents where
mstats differs from MemStats.
Fixes#15849.
Change-Id: Ie09374bcdb3a5fdd2d25fe4bba836aaae92cb1dd
Reviewed-on: https://go-review.googlesource.com/28972
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
We used to compute an estimate of the reachable heap size that was
different from the marked heap size. This ultimately caused more
problems than it solved, so we pulled it out, but memstats still has
both heap_reachable and heap_marked, and there are some leftover TODOs
about the problems with this estimate.
Clean this up by eliminating heap_reachable in favor of heap_marked
and deleting the stale TODOs.
Change-Id: I713bc20a7c90683d2b43ff63c0b21a440269cc4d
Reviewed-on: https://go-review.googlesource.com/29271
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Back in Go 1.4, memstats.next_gc was both the heap size at which GC
would trigger, and the size GC kept the heap under. When we switched
to concurrent GC in Go 1.5, we got somewhat confused and made this
variable the trigger heap size, while gcController.heapGoal became the
goal heap size.
memstats.next_gc is exposed to the user via MemStats.NextGC, while
gcController.heapGoal is not. This is unfortunate because 1) the heap
goal is far more useful for diagnostics, and 2) the trigger heap size
is just part of the GC trigger heuristic, which means it wouldn't be
useful to an application even if it tried to use it.
We never noticed this mess because MemStats.NextGC is practically
undocumented. Now that we're trying to document MemStats, it became
clear that this field had diverged from its original usefulness.
Clean up this mess by shuffling things back around so that next_gc is
the goal heap size and the new (unexposed) memstats.gc_trigger field
is the trigger heap size. This eliminates gcController.heapGoal.
Updates #15849.
Change-Id: I2cbbd43b1d78bdf613cb43f53488bd63913189b7
Reviewed-on: https://go-review.googlesource.com/29270
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
All the variants that sets the new signal mask in minit do the same
thing, so merge them. This requires an OS-specific sigdelset function;
the function already exists for linux, and is now added for other OS's.
Change-Id: Ie96f6f02e2cf09c43005085985a078bd9581f670
Reviewed-on: https://go-review.googlesource.com/29771
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Added rules for compare double and word immediate,
including those that use invertflags to cope with
flipped operands.
Change-Id: I594430a210e076e52299a2cc6ab074dbb04a02bd
Reviewed-on: https://go-review.googlesource.com/29763
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Combine the various versions of sigtrampgo into a single function in
signal_unix.go. This requires defining a fixsigcode method on sigctxt
for all operating systems; it only does something on Darwin. This also
requires changing the darwin/amd64 signal handler to call sigreturn
itself, rather than relying on sigtrampgo to call sigreturn for it. We
can then drop the Darwin sigreturn function, as it is no longer used.
Change-Id: I5a0b9d2d2c141957e151b41e694efeb20e4b4b9a
Reviewed-on: https://go-review.googlesource.com/29761
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
There's no load-signed-byte on PPC, so MOVB
causes the assembler to macro-expand in a
useless sign extension.
Fixes#17211.
Change-Id: Ibcd73aea4c94ba6df0a998b0091e45508113be2a
Reviewed-on: https://go-review.googlesource.com/29762
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <munday@ca.ibm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When processing a fallthrough, the casebody function in swt.go
checks that the last statement has indeed Op == OXFALL (not-processed
fallthrough) before setting it to OFALL (processed fallthrough).
Unfortunately, sometimes the fallthrough statement won't be in the
last node. For example, in
case 0:
return func() int {return 1}()
fallthrough
the compiler generates
autotmp_0 = (func literal)(); return autotmp_0; fallthrough; <node VARKILL>
with an OVARKILL node in the last position. casebody will find that
last.Op != OXFALL, won't mark the fallthrough as processed, and the
fallthrough line will cause a "fallthrough statement out of place" error.
To fix this, we change casebody so that it searches for the fallthrough
statement backwards in the statements list, without assuming that it'll
be in the last position.
Fixes#13262
Change-Id: I366c6caa7fd7442d365bd7a08cc66a552212d9b2
Reviewed-on: https://go-review.googlesource.com/22921
Run-TryBot: Quentin Smith <quentin@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Quentin Smith <quentin@golang.org>
Change all Unix systems to use stackt for the alternate signal
stack (some were using sigaltstackt). Add OS-specific setSignalstackSP
function to handle different types for ss_sp field, and unify all
OS-specific signalstack functions into one. Unify handling of alternate
signal stack in OS-specific minit and sigtrampgo functions via new
functions minitSignalstack and setGsignalStack.
Change-Id: Idc316dc69b1dd725717acdf61a1cd8b9f33ed174
Reviewed-on: https://go-review.googlesource.com/29757
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Add a method to expose the handler to allow it to be installed at a
non-standard location or used with a different ServeMux.
fixes#15030
Change-Id: If778ad6fcc200f124a05c0a493511e364fca6078
Reviewed-on: https://go-review.googlesource.com/24722
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Implement a comment by Ralph Corderoy on CL 29754.
Change-Id: I22bbede211ddcb8a057f16b4f47d335a156cc8d2
Reviewed-on: https://go-review.googlesource.com/29756
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Currently raceSymbolizeCode uses funcline, which is internal runtime
function which crashes on incorrect PCs. Use FileLine instead,
it is public and does not crash on invalid data.
Note: FileLine returns "?" file on failure. That string is not NUL-terminated,
so we need to additionally check what FileLine returns.
Fixes#17190
Change-Id: Ic6fbd4f0e68ddd52e9b2dd25e625b50adcb69a98
Reviewed-on: https://go-review.googlesource.com/29714
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Don't write line info for types, we don't have it.
Otherwise types look like:
type _Ctype_struct_cb struct {
//line :1
on_test *[0]byte
//line :1
}
Which is not useful. Moreover we never override source info,
so subsequent source code uses the same source info.
Moreover, empty file name makes compile emit no source debug info at all.
Update #17190
Change-Id: I7ae6fa4964520d7665743d340419b787df0b51e8
Reviewed-on: https://go-review.googlesource.com/29713
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
PC passed to racegostart is expected to be a return PC
of the go statement. Race runtime will subtract 1 from the PC
before symbolization. Passing start PC of a function is wrong.
Add sys.PCQuantum to the function start PC.
Update #17190
Change-Id: Ia504c49e79af84ed4ea360c2aea472b370ea8bf5
Reviewed-on: https://go-review.googlesource.com/29712
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This sentence is partially guilty why httptrace is considered as an
http.Client tracing package. Removing the mention.
Updates #17152.
Change-Id: I69f78a6e10817db933f44e464a949ae896e44ec6
Reviewed-on: https://go-review.googlesource.com/29755
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Replace all the Unix sighandler functions with a single instance.
Push the relatively small amount of processor-specific code into five
methods on sigctxt: sigpc, sigsp, siglr, fault, preparePanic.
(Some processors already had a fault method.)
Change-Id: Ib459412ff8f7e0f5ad06bfd43eb827c8b196fc32
Reviewed-on: https://go-review.googlesource.com/29752
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Takes a bit too long to run it all the time.
Fixes#17217
Update #17104
Change-Id: I4802190ea16ee0f436a7f95b093ea0f995f5b11d
Reviewed-on: https://go-review.googlesource.com/29751
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Unify the OS-specific versions of msigsave, msigrestore, sigblock,
updatesigmask, and unblocksig into single versions in signal_unix.go.
To do this, make sigprocmask work the same way on all systems, which
required adding a definition of sigprocmask for linux and openbsd.
Also add a single OS-specific function sigmaskToSigset.
Change-Id: I7cbf75131dddb57eeefe648ef845b0791404f785
Reviewed-on: https://go-review.googlesource.com/29689
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This CL turns some special section marker symbols into real symbols
laid out in the sections they mark. This is to deal with the fact
that dyld on OS X resolves the section marker symbols in any dlopen-ed
Go program to the original section marker symbols in the host program.
More details in a comment in cmd/link/internal/ld/data.go.
Change-Id: Ie9451cfbf06d0bdcccb9959219c791b829f3f771
Reviewed-on: https://go-review.googlesource.com/29394
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The 2-byte rule was firing before the 4-byte rule, preventing
the 4-byte rule from firing. Update the 4-byte rule to use
the results of the 2-byte rule instead.
Add some tests to make sure we don't regress again.
Fixes#17147
Change-Id: Icfeccd9f2b96450981086a52edd76afb3191410a
Reviewed-on: https://go-review.googlesource.com/29382
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Before this change a nil check on s390x could be scheduled after the
target pointer has been dereferenced.
Change-Id: I7ea40a4b52f975739f6db183a2794be4981c4e3d
Reviewed-on: https://go-review.googlesource.com/29730
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This adds the instructions frim, frip, and friz to the ppc64x
assembler for use in implementing the math.Floor, math.Ceil, and
math.Trunc functions to improve performance.
Fixes#17185
BenchmarkCeil-128 21.4 6.99 -67.34%
BenchmarkFloor-128 13.9 6.37 -54.17%
BenchmarkTrunc-128 12.7 6.33 -50.16%
Change-Id: I96131bd4e8c9c8dbafb25bfeb544cf9d2dbb4282
Reviewed-on: https://go-review.googlesource.com/29654
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Michael Munday <munday@ca.ibm.com>
Attempt to fix the linux-amd64-clang builder, which broke
with CL 29472.
Turns out pthread_yield is a non-portable Linux function, and
should have #define _GNU_SOURCE before #include <pthread.h>.
GCC doesn't complain about this, but Clang does:
./raceprof.go:44:3: warning: implicit declaration of function 'pthread_yield' is invalid in C99 [-Wimplicit-function-declaration]
(Though the error, while explicable, certainly could be clearer.)
There is a portable POSIX equivalent, sched_yield, so this
CL uses it instead.
Change-Id: I58ca7a3f73a2b3697712fdb02e72a8027c391169
Reviewed-on: https://go-review.googlesource.com/29675
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Inspired by difficulties with plugin support on darwin.
Change-Id: I2cef8410837946454e75d00e94e46791f03f2267
Reviewed-on: https://go-review.googlesource.com/29391
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Instrumenting copy and append for the race detector changes them to call
different functions. In the runtime package the alternate functions are
not marked as nosplit. This caused a crash in the SIGPROF handler when
invoked on a non-Go thread in a program built with the race detector. In
some cases the handler can call copy, the race detector changed that to
a call to a non-nosplit function, the function tried to check the stack
guard, and crashed because it was running on a non-Go thread. The
SIGPROF handler is written carefully to avoid such problems, but hidden
function calls are difficult to avoid.
Fix this by changing the compiler to not instrument copy and append when
compiling the runtime package. Change the runtime package to add
explicit race checks for the only code I could find where copy is used
to write to user data (append is never used).
Change-Id: I11078a66c0aaa459a7d2b827b49f4147922050af
Reviewed-on: https://go-review.googlesource.com/29472
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
var x *X = ...
defer x.foo()
As part of the defer, we need to calculate &(*X).foo·f. This expression
is the address of the static closure that will call (*X).foo when a
pointer to that closure is used in a call/defer/go. This pointer is not
currently properly typed in SSA. It is a pointer type, but the base
type is nil, not a proper type.
This turns out not to be a problem currently because we never use the
type of these SSA values. But I'm trying to change that (to be able to
spill them) in CL 28391. To fix, use uint8 as the fake type of the
closure.
Change-Id: Ieee388089c9af398ed772ee8c815122c347cb633
Reviewed-on: https://go-review.googlesource.com/29444
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
On link-register machines we uses RET (sym), instead of JMP (sym),
for tail call (so the assembler knows and may rewrite it to
restore link register if necessary). Add RET to the analysis.
Fixes#17186.
Fixes#16016 on link-register machines.
Change-Id: I8690ac57dd9d49beeea76a5f291988e9a1d3afe5
Reviewed-on: https://go-review.googlesource.com/29570
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
After renegotiation support was added (af125a5193) it's possible for a
Write to block on a Read when racing to complete the handshake:
1. The Write determines that a handshake is needed and tries to
take the neccesary locks in the correct order.
2. The Read also determines that a handshake is needed and wins
the race to take the locks.
3. The Read goroutine completes the handshake and wins a race
to unlock and relock c.in, which it'll hold when waiting for
more network data.
If the application-level protocol requires the Write to complete before
data can be read then the system as a whole will deadlock.
Unfortunately it doesn't appear possible to reverse the locking order of
c.in and handshakeMutex because we might read a renegotiation request at
any point and need to be able to do a handshake without unlocking.
So this change adds a sync.Cond that indicates that a goroutine has
committed to doing a handshake. Other interested goroutines can wait on
that Cond when needed.
The test for this isn't great. I was able to reproduce the deadlock with
it only when building with -race. (Because -race happened to alter the
timing just enough.)
Fixes#17101.
Change-Id: I4e8757f7b82a84e46c9963a977d089f0fb675495
Reviewed-on: https://go-review.googlesource.com/29164
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This change modifies URL.String to prepend "./" to a relative URL which
contains a colon in the first path segment.
Per RFC 3986 §4.2:
> A path segment that contains a colon character (e.g., "this:that")
> cannot be used as the first segment of a relative-path reference, as
> it would be mistaken for a scheme name. Such a segment must be
> preceded by a dot-segment (e.g., "./this:that") to make a relative-
> path reference.
https://go-review.googlesource.com/27440 corrects the behavior for http.FileServer,
but URL.String will still return an invalid URL. This CL reverts the changes to
http.FileServer as they are unnecessary with this fix.
Fixes#17184
Change-Id: I9211ae20f82c91b785d1b079b2cd766487d94225
Reviewed-on: https://go-review.googlesource.com/29610
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Abandoned earlier efforts to expose zero register,
but left it in numbering to decrease squirrelyness of
register allocator.
ISELrelOp used in code generation of bool := x relOp y.
Some patterns added to better elide zero case and
some sign extension.
Updates: #17109
Change-Id: Ida7839f0023ca8f0ffddc0545f0ac269e65b05d9
Reviewed-on: https://go-review.googlesource.com/29380
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
