Update #6853
For an ephemeral binary - one created, run, and then deleted -
there is no need to write dwarf debug information, since the
binary will not be used with gdb. In this case, instruct the linker
not to spend time and disk space generating the debug information
by passing the -w flag to the linker.
Omitting dwarf information reduces the size of most binaries by 25%.
We may be more aggressive about this in the future.
LGTM=bradfitz, r
R=r, bradfitz
CC=golang-codereviews
https://golang.org/cl/65890043
Update #6853
Every function now has a gcargs and gclocals symbol
holding associated garbage collection information.
Put them all in the same meta-symbol as the go.func data
and then drop individual entries from symbol table.
Removing gcargs and gclocals reduces the size of a
typical binary by 10%.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/65870044
IsNil isn't quite the same as == nil, as this snippet shows:
// http://play.golang.org/p/huomslDZgw
package main
import "fmt"
import "reflect"
func main() {
var i interface{}
v := reflect.ValueOf(i)
fmt.Println(v.IsValid(), i == nil)
fmt.Println(v.IsNil())
}
The fact that IsNil panics if you call it with an untyped nil
was not apparent. Verbiage added for clarity.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/65480043
Update #6853
Nothing reads the Plan 9 symbol table anymore.
The last holdout was 'go tool nm', but since being rewritten in Go
it uses the standard symbol table for the binary format
(ELF, Mach-O, PE) instead.
Removing the Plan 9 symbol table saves ~15% disk space
on most binaries.
Two supporting changes included in this CL:
debug/gosym: use Go 1.2 pclntab to synthesize func-only
symbol table when there is no Plan 9 symbol table
debug/elf, debug/macho, debug/pe: ignore final EOF from ReadAt
LGTM=r
R=r, bradfitz
CC=golang-codereviews
https://golang.org/cl/65740045
c-mode classically uses ff-find-other-file to toggle between headers
and implementation. For Go it seemingly makes sense to jump between
implementation and test.
While there's no enforced mapping of file names for tests, the mapping
in this CL seems to be very common at least throughout the standard
library, and ff-find-other-file fails gracefully when the mapping
doesn't apply.
LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://golang.org/cl/65750044
The code was returning the original value rather than the cloned value
resulting in the tests not being repeatable.
Fixes#7111.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/65720045
This is a relatively minor change.
This does not result in changes to go.text/unicode/norm. The go.text
packages will therefore be relatively unaffected. It does make the
way for an upgrade to CLDR 24, though.
The tests of all.bash pass, as well as the tests in go.text after
this update.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/65400044
broke 32-bit builds
««« original CL description
cmd/gc, runtime: enable precisestack by default
Precisestack makes stack collection completely precise,
in the sense that there are no "used and not set" errors
in the collection of stack frames, no times where the collector
reads a pointer from a stack word that has not actually been
initialized with a pointer (possibly a nil pointer) in that function.
The most important part is interfaces: precisestack means
that if reading an interface value, the interface value is guaranteed
to be initialized, meaning that the type word can be relied
upon to be either nil or a valid interface type word describing
the data word.
This requires additional zeroing of certain values on the stack
on entry, which right now costs about 5% overall execution
time in all.bash. That cost will come down before Go 1.3
(issue 7345).
There are at least two known garbage collector bugs right now,
issues 7343 and 7344. The first happens even without precisestack.
The second I have only seen with precisestack, but that does not
mean that precisestack is what causes it. In fact it is very difficult
to explain by what precisestack does directly. Precisestack may
be exacerbating an existing problem. Both of those issues are
marked for Go 1.3 as well.
The reasons for enabling precisestack now are to give it more
time to soak and because the copying stack work depends on it.
LGTM=r
R=r
CC=golang-codereviews, iant, khr
https://golang.org/cl/64100044
»»»
TBR=r
CC=golang-codereviews
https://golang.org/cl/65230043
Precisestack makes stack collection completely precise,
in the sense that there are no "used and not set" errors
in the collection of stack frames, no times where the collector
reads a pointer from a stack word that has not actually been
initialized with a pointer (possibly a nil pointer) in that function.
The most important part is interfaces: precisestack means
that if reading an interface value, the interface value is guaranteed
to be initialized, meaning that the type word can be relied
upon to be either nil or a valid interface type word describing
the data word.
This requires additional zeroing of certain values on the stack
on entry, which right now costs about 5% overall execution
time in all.bash. That cost will come down before Go 1.3
(issue 7345).
There are at least two known garbage collector bugs right now,
issues 7343 and 7344. The first happens even without precisestack.
The second I have only seen with precisestack, but that does not
mean that precisestack is what causes it. In fact it is very difficult
to explain by what precisestack does directly. Precisestack may
be exacerbating an existing problem. Both of those issues are
marked for Go 1.3 as well.
The reasons for enabling precisestack now are to give it more
time to soak and because the copying stack work depends on it.
LGTM=r
R=r
CC=golang-codereviews, iant, khr
https://golang.org/cl/64100044
I have seen this cause leaks where not all objects in a sync.Pool
would be reclaimed during the sync package tests.
I found it while debugging the '0 of 100 finalized' failure we are
seeing on arm, but it seems not to be the root cause for that one.
LGTM=dave, dvyukov
R=golang-codereviews, dave, dvyukov
CC=golang-codereviews
https://golang.org/cl/64920044
Callers of md5.Sum should do so to avoid allocations, the example did not demonstate this property.
««« original CL description
crypto/md5: add example for Sum
LGTM=dave
R=golang-codereviews, dave
CC=golang-codereviews
https://golang.org/cl/64820044
»»»
LGTM=minux.ma
R=r, minux.ma
CC=golang-codereviews
https://golang.org/cl/65180043
Add b.RunParallel function that captures parallel benchmark boilerplate:
creates worker goroutines, joins worker goroutines, distributes work
among them in an efficient way, auto-tunes grain size.
Fixes#7090.
R=bradfitz, iant, josharian, tracey.brendan, r, rsc, gobot
CC=golang-codereviews
https://golang.org/cl/57270043
CL 64170043 disabled it in run.bash for Unix systems.
I did not realize Windows systems also ran the race detector test.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/64480043
Not recording the address being taken was causing
the liveness analysis not to preserve x in the absence
of direct references to x, which in turn was making the
net test fail with GOGC=0.
In addition to the test, this fixes a bug wherein
GOGC=0 go test -short net
crashed if liveness analysis was in use (like at tip, not like Go 1.2).
TBR=ken2
CC=golang-codereviews
https://golang.org/cl/64470043
This problem was discovered by reading the code.
I have not seen it in practice, nor do I have any ideas
on how to trigger it reliably in a test. But it's still worth
fixing.
TBR=ken2
CC=golang-codereviews
https://golang.org/cl/64370046
The VARDEF placement must be before the initialization
but after any final use. If you have something like s = ... using s ...
the rhs must be evaluated, then the VARDEF, then the lhs
assigned.
There is a large comment in pgen.c on gvardef explaining
this in more detail.
This CL also includes Ian's suggestions from earlier CLs,
namely commenting the use of mode in link.h and fixing
the precedence of the ~r check in dcl.c.
This CL enables the check that if liveness analysis decides
a variable is live on entry to the function, that variable must
be a function parameter (not a result, and not a local variable).
If this check fails, it indicates a bug in the liveness analysis or
in the generated code being analyzed.
The race detector generates invalid code for append(x, y...).
The code declares a temporary t and then uses cap(t) before
initializing t. The new liveness check catches this bug and
stops the compiler from writing out the buggy code.
Consequently, this CL disables the race detector tests in
run.bash until the race detector bug can be fixed
(golang.org/issue/7334).
Except for the race detector bug, the liveness analysis check
does not detect any problems (this CL and the previous CLs
fixed all the detected problems).
The net test still fails with GOGC=0 but the rest of the tests
now pass or time out (because GOGC=0 is so slow).
TBR=iant
CC=golang-codereviews
https://golang.org/cl/64170043
The existing tests issue4463.go and issue4654.go had failures at
typechecking and did not test walking the AST.
Fixes#7272.
LGTM=khr
R=khr, rsc, iant
CC=golang-codereviews
https://golang.org/cl/60550044
Catch the error instead and return it to the user. Before this fix,
the template package panicked. Now you get:
template: bug11:1:14: executing "bug11" at <.PS>: dereference of nil pointer of type *string
Extended example at http://play.golang.org/p/uP6pCW3qKTFixes#7333.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/64150043
These should never be found in a bzip2 file but it does appear that
there's a buggy encoder that is producing them. Since the official
bzip2 handles this case, this change makes the Go code do likewise.
With this change, the code produces the same output as the official
bzip2 code on the invalid example given in the bug.
Fixes#7279.
LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/64010043
Rfork is not splitting the stack when creating a new thread,
so the parent and child are executing on the same stack.
However, if the parent returns and keeps executing before
the child can read the arguments from the parent stack,
the child will not see the right arguments. The solution
is to load the needed pieces from the parent stack into
register before INT $64.
Thanks to Russ Cox for the explanation.
LGTM=rsc
R=rsc
CC=ality, golang-codereviews
https://golang.org/cl/64140043
A previous CL added support for cross compiling with cgo, but
missed the GOOS check in cmd/go. Remove it.
Update #4714
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/57210046
Changing the PC confuses gdb, because execution does not
continue where gdb expects it. Not changing the PC has the
potential to confuse a stack dump, but when running under gdb
it seems better to confuse a stack dump than to confuse gdb.
Fixes#6776.
LGTM=rsc
R=golang-codereviews, dvyukov, rsc
CC=golang-codereviews
https://golang.org/cl/49580044
On Linux include/net directory is just to help porting applications
from BSDs and files under net keep less information than include/linux.
Making use of files under include/linux instead of include/net prevents
lack of information.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/63930043
The following checkdead message is false positive:
$ go test -race -c runtime
$ ./runtime.test -test.cpu=2 -test.run=TestSmhasherWindowed -test.v
=== RUN TestSmhasherWindowed-2
checkdead: find g 18 in status 1
SIGABRT: abort
PC=0x42bff1
LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews, iant, khr
https://golang.org/cl/59490046
Currently small and large (size>rate) objects are merged into a single entry.
But rate adjusting is required only for small objects.
As a result pprof either incorrectly adjusts large objects
or does not adjust small objects.
With this change objects of different sizes are stored in different buckets.
LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/59220049
When the liveness code doesn't know a function doesn't return
(but the generated code understands that), the liveness analysis
invents a control flow edge that is not really there, which can cause
variables to seem spuriously live. This is particularly bad when the
variables are uninitialized.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/63720043
Currently it periodically fails with the following message.
The immediate cause is the wrong base register when obtaining g
in sys_windows_amd64/386.s.
But there are several secondary problems as well.
runtime: unknown pc 0x0 after stack split
panic: invalid memory address or nil pointer dereference
fatal error: panic during malloc
[signal 0xc0000005 code=0x0 addr=0x60 pc=0x42267a]
runtime stack:
runtime.panic(0x7914c0, 0xc862af)
c:/src/perfer/work/windows-amd64-a15f344a9efa/go/src/pkg/runtime/panic.c:217 +0x2c
runtime: unexpected return pc for runtime.externalthreadhandler called from 0x0
R=rsc, alex.brainman
CC=golang-codereviews
https://golang.org/cl/63310043
The registerization code needs the function to end in a RET,
even if that RET is actually unreachable.
The liveness code needs to avoid such unreachable RETs.
It had a special case for final RET after JMP, but no case
for final RET after UNDEF. Instead of expanding the special
cases, let fixjmp - which already knows what is and is not
reachable definitively - mark the unreachable RET so that
the liveness code can identify it.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/63680043
A normal RET is treated as using the return values,
but a tail jump RET does not - it is jumping to the
function that is going to fill in the return values.
If a tail jump RET is recorded as using the return values,
since nothing initializes them they will be marked as
live on entry to the function, which is clearly wrong.
Found and tested by the new code in plive.c that looks
for variables that are incorrectly live on entry.
That code is disabled for now because there are other
cases remaining to be fixed. But once it is enabled,
test/live1.go becomes a real test of this CL.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/63570045
Any initialization of a variable by a block copy or block zeroing
or by multiple assignments (componentwise copying or zeroing
of a multiword variable) needs to emit a VARDEF. These cases were not.
Fixes#7205.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/63650044
The test added in CL 63630043 fails on 5g and 8g because they
were not emitting the VARDEF instruction when clearing a fat
value by clearing the components. 6g had the call in the right place.
Hooray tests.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/63660043
