Call frame allocations can account for significant portion
of all allocations in a program, if call is executed
in an inner loop (e.g. to process every line in a log).
On the other hand, the allocation is easy to remove
using sync.Pool since the allocation is strictly scoped.
benchmark old ns/op new ns/op delta
BenchmarkCall 634 338 -46.69%
BenchmarkCall-4 496 167 -66.33%
benchmark old allocs new allocs delta
BenchmarkCall 1 0 -100.00%
BenchmarkCall-4 1 0 -100.00%
Update #7818
Change-Id: Icf60cce0a9be82e6171f0c0bd80dee2393db54a7
Reviewed-on: https://go-review.googlesource.com/1954
Reviewed-by: Keith Randall <khr@golang.org>
Currently we scan maps even if k/v does not contain pointers.
This is required because overflow buckets are hanging off the main table.
This change introduces a separate array that contains pointers to all
overflow buckets and keeps them alive. Buckets themselves are marked
as containing no pointers and are not scanned by GC (if k/v does not
contain pointers).
This brings maps in line with slices and chans -- GC does not scan
their contents if elements do not contain pointers.
Currently scanning of a map[int]int with 2e8 entries (~8GB heap)
takes ~8 seconds. With this change scanning takes negligible time.
Update #9477.
Change-Id: Id8a04066a53d2f743474cad406afb9f30f00eaae
Reviewed-on: https://go-review.googlesource.com/3288
Reviewed-by: Keith Randall <khr@golang.org>
For a non-zero-sized struct with a final zero-sized field,
add a byte to the size (before rounding to alignment). This
change ensures that taking the address of the zero-sized field
will not incorrectly leak the following object in memory.
reflect.funcLayout also needs this treatment.
Fixes#9401
Change-Id: I1dc503dc5af4ca22c8f8c048fb7b4541cc957e0f
Reviewed-on: https://go-review.googlesource.com/2452
Reviewed-by: Russ Cox <rsc@golang.org>
Use typedmemmove, typedslicecopy, and adjust reflect.call
to execute the necessary write barriers.
Found with GODEBUG=wbshadow=2 mode.
Eventually that will run automatically, but right now
it still detects other missing write barriers.
Change-Id: Iec5b5b0c1be5589295e28e5228e37f1a92e07742
Reviewed-on: https://go-review.googlesource.com/2312
Reviewed-by: Keith Randall <khr@golang.org>
The goalg function was a holdover from when we had algorithm
tables in both C and Go. It is no longer needed.
Change-Id: Ia0c1af35bef3497a899f22084a1a7b42daae72a0
Reviewed-on: https://go-review.googlesource.com/2099
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This test code is ugly. There must be a better way.
But for now, fix the build.
Change-Id: I33064145ea37f11abf040ec97caa87669be1a9fa
Reviewed-on: https://go-review.googlesource.com/2114
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Test more stuff:
1) flagNoPointers, an incorrect value was the cause of #9425
2) Total function layout size
3) gc program
Change-Id: I73f65fe740215938fa930d2f096febd9db0a0021
Reviewed-on: https://go-review.googlesource.com/2090
Reviewed-by: Ian Lance Taylor <iant@golang.org>
malloc checks kindNoPointers and if it is not set and the object
is one pointer in size, it assumes it contains a pointer. So we
must set kindNoPointers correctly; it isn't just a hint.
Fixes#9425
Change-Id: Ia43da23cc3298d6e3d6dbdf66d32e9678f0aedcf
Reviewed-on: https://go-review.googlesource.com/2055
Reviewed-by: Russ Cox <rsc@golang.org>
Pointers to zero-sized values may end up pointing to the next
object in memory, and possibly off the end of a span. This
can cause memory leaks and/or confuse the garbage collector.
By putting the overflow pointer at the end of the bucket, we
make sure that pointers to any zero-sized keys or values don't
accidentally point to the next object in memory.
fixes#9384
Change-Id: I5d434df176984cb0210b4d0195dd106d6eb28f73
Reviewed-on: https://go-review.googlesource.com/1869
Reviewed-by: Russ Cox <rsc@golang.org>
Most types are reflexive (k == k for all k of type t), so don't
bother calling equal(k, k) when the key type is reflexive.
Change-Id: Ia716b4198b8b298687843b94b878dbc5e8fc2c65
Reviewed-on: https://go-review.googlesource.com/1480
Reviewed-by: Russ Cox <rsc@golang.org>
This is to reduce the delta between dev.cc and dev.garbage to just garbage collector changes.
These are the files that had merge conflicts and have been edited by hand:
malloc.go
mem_linux.go
mgc.go
os1_linux.go
proc1.go
panic1.go
runtime1.go
LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/174180043
[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]
Adjustments for changes made in CL 169360043.
This change is already present in the dev.garbage branch.
LGTM=r
R=r
CC=austin, golang-codereviews, iant, khr
https://golang.org/cl/167520044
reflect/asm_power64x.s was missing changes made to other
platforms for stack maps. This CL ports those changes. With
this fix, the reflect test passes on power64x.
LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/170870043
This brings dev.power64 up-to-date with the current tip of
default. go_bootstrap is still panicking with a bad defer
when initializing the runtime (even on amd64).
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/152570049
This also removes pkg/runtime/traceback_lr.c, which was ported
to Go in an earlier commit and then moved to
runtime/traceback.go.
Reviewer: rsc@golang.org
rsc: LGTM
This test was failing but did not break the build because it
was not run when -test.short was used.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/157150043
I came across this while debugging a GC problem in gccgo.
There is code in assignTo and cvtT2I that handles assignment
to all interface values. It allocates an empty interface even
if the real type is a non-empty interface. The fields are
then set for a non-empty interface, but the memory is recorded
as holding an empty interface. This means that the GC has
incorrect information.
This is extremely unlikely to fail, because the code in the GC
that handles empty interfaces looks like this:
obj = nil;
typ = eface->type;
if(typ != nil) {
if(!(typ->kind&KindDirectIface) || !(typ->kind&KindNoPointers))
obj = eface->data;
In the current runtime the condition is always true--if
KindDirectIface is set, then KindNoPointers is clear--and we
always want to set obj = eface->data. So the question is what
happens when we incorrectly store a non-empty interface value
in memory marked as an empty interface. In that case
eface->type will not be a *rtype as we expect, but will
instead be a pointer to an Itab. We are going to use this
pointer to look at a *rtype kind field. The *rtype struct
starts out like this:
type rtype struct {
size uintptr
hash uint32 // hash of type; avoids computation in hash tables
_ uint8 // unused/padding
align uint8 // alignment of variable with this type
fieldAlign uint8 // alignment of struct field with this type
kind uint8 // enumeration for C
An Itab always has at least two pointers, so on a
little-endian 64-bit system the kind field will be the high
byte of the second pointer. This will normally be zero, so
the test of typ->kind will succeed, which is what we want.
On a 32-bit system it might be possible to construct a failing
case by somehow getting the Itab for an interface with one
method to be immediately followed by a word that is all ones.
The effect would be that the test would sometimes fail and the
GC would not mark obj, leading to an invalid dangling
pointer. I have not tried to construct this test.
I noticed this in gccgo, where this error is much more likely
to cause trouble for a rather random reason: gccgo uses a
different layout of rtype, and in gccgo the kind field happens
to be the low byte of a pointer, not the high byte.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/155450044
Replace i < 0 || i >= x with uint(i) >= uint(x).
Shorten a few other code sequences.
Move the kind bits to the bottom of the flag word, to avoid shifts.
LGTM=r
R=r, bradfitz
CC=golang-codereviews
https://golang.org/cl/159020043
The code for a generated type is already generating an
unrolled GC bitmask. Rather than unrolling the the source
type bitmasks and copying them, just generate the required
bitmask directly. Don't mark it as an unrolled GC program,
since there is no need to do so.
Fixes#8917.
LGTM=rsc
R=dvyukov, rsc
CC=golang-codereviews
https://golang.org/cl/156930044
TestMakeFuncVariadic only called the variadic function via Call and
CallSlice, not via a direct function call.
I thought these tests would fail under gccgo tip, but they don't. Still seems worth having though.
LGTM=iant
R=golang-codereviews, gobot, iant
CC=golang-codereviews
https://golang.org/cl/152060043
These tests fail when using gccgo. In gccgo using Interface
on the value of a method function is implemented using a
variant of MakeFunc. That approach did not correctly handle
variadic functions.
LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/151280043
Depending on flags&KindGCProg,
gc[0] and gc[1] are either pointers or inlined bitmap bits.
That's not compatible with a precise garbage collector:
it needs to be always pointers or never pointers.
Change the inlined bitmap case to store a pointer to an
out-of-line bitmap in gc[0]. The out-of-line bitmaps are
dedup'ed, so that for example all pointer types share the
same out-of-line bitmap.
Fixes#8864.
LGTM=r
R=golang-codereviews, dvyukov, r
CC=golang-codereviews, iant, khr, rlh
https://golang.org/cl/155820043
Like most of the Type methods, the definition of Comparable
is what the Go spec says it is.
Fixes#7911.
LGTM=gri
R=gri, r
CC=golang-codereviews
https://golang.org/cl/144020043
makeFuncStub and methodValueStub are used by reflect as
generic function implementations. Each call might have
different arguments. Extract those arguments from the
closure data instead of assuming it is the same each time.
Because the argument map is now being extracted from the
function itself, we don't need the special cases in reflect.Call
anymore, so delete those.
Fixes an occasional crash seen when stack copying does
not update makeFuncStub's arguments correctly.
Will also help make it safe to require stack maps in the
garbage collector.
Derived from CL 142000044 by khr.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/143890044
They will both need write barriers at some point.
But until then, no reason why we shouldn't share.
LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/141330043
