gccgo has problems using reflect.Call with functions that take and
return structs with no members. Prior to fixing that problem there, I
thought it sensible to add some tests of this situation.
Update #6761
First contribution to Go, apologies in advance if I'm doing it wrong.
R=golang-dev, dave, minux.ma, iant, khr, bradfitz
CC=golang-dev
https://golang.org/cl/26570046
and methodValueCall directly. Instead, we inline their behavior
inside of reflect.call.
This change is required because otherwise we have a situation where
reflect.callXX calls makeFuncStub, neither of which knows the
layout of the args passed between them. That's bad for
precise gc & stack copying.
Fixes#6619.
R=golang-dev, dvyukov, rsc, iant, khr
CC=golang-dev
https://golang.org/cl/26970044
This change is part of the plan to get rid of all vararg C calls
which are a pain for getting exact stack scanning.
We allocate a chunk of zero memory to return a pointer to when a
map access doesn't find the key. This is simpler than returning nil
and fixing things up in the caller. Linker magic allocates a single
zero memory area that is shared by all (non-reflect-generated) map
types.
Passing things by reference gets rid of some copies, so it speeds
up code with big keys/values.
benchmark old ns/op new ns/op delta
BenchmarkBigKeyMap 34 31 -8.48%
BenchmarkBigValMap 37 30 -18.62%
BenchmarkSmallKeyMap 26 23 -11.28%
R=golang-dev, dvyukov, khr, rsc
CC=golang-dev
https://golang.org/cl/14794043
Failure occurred when using reflect.Call to pass a func value
following a non-pointer value.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/14186043
The argument slice was kept hidden from the garbage collector
by destroying its referent in an unsafe.Pointer to uintptr
conversion. This change preserves the unsafe.Pointer referent
and only performs an unsafe.Pointer to uintptr conversions
within expressions that construct new unsafe.Pointer values.
R=golang-dev, khr, rsc
CC=golang-dev
https://golang.org/cl/14008043
Bug #1:
Issue 5406 identified an interesting case:
defer iface.M()
may end up calling a wrapper that copies an indirect receiver
from the iface value and then calls the real M method. That's
two calls down, not just one, and so recover() == nil always
in the real M method, even during a panic.
[For the purposes of this entire discussion, a wrapper's
implementation is a function containing an ordinary call, not
the optimized tail call form that is somtimes possible. The
tail call does not create a second frame, so it is already
handled correctly.]
Fix this bug by introducing g->panicwrap, which counts the
number of bytes on current stack segment that are due to
wrapper calls that should not count against the recover
check. All wrapper functions must now adjust g->panicwrap up
on entry and back down on exit. This adds slightly to their
expense; on the x86 it is a single instruction at entry and
exit; on the ARM it is three. However, the alternative is to
make a call to recover depend on being able to walk the stack,
which I very much want to avoid. We have enough problems
walking the stack for garbage collection and profiling.
Also, if performance is critical in a specific case, it is already
faster to use a pointer receiver and avoid this kind of wrapper
entirely.
Bug #2:
The old code, which did not consider the possibility of two
calls, already contained a check to see if the call had split
its stack and so the panic-created segment was one behind the
current segment. In the wrapper case, both of the two calls
might split their stacks, so the panic-created segment can be
two behind the current segment.
Fix this by propagating the Stktop.panic flag forward during
stack splits instead of looking backward during recover.
Fixes#5406.
R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/13367052
But keep their case for ease of searching.
They were added recently. We don't want them part of go1.2's API.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/13569044
DeepEqual caches addresses of compared values
each time it visits addressable values. This is
more expensive than actually comparing them in
the common case of large slices of bytes or integers.
Also add a fast path for slices with identical
underlying array.
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13000044
pointer. An example that triggers the bad behavior on a 64bit
machine http://play.golang.org/p/GrNFakAYLN
rv1 := reflect.ValueOf(complex128(0))
rt := rv1.Type()
rv2 := rv1.Convert(rt)
rv3 := reflect.New(rt).Elem()
rv3.Set(rv2)
Running the code fails with the following:
panic: reflect: internal error: storeIword of 16-byte value
I've tested on a 64bit machine and verified this fixes the panic. I
haven't tested on a 32bit machine so I haven't verified the other
cases, but they follow logically.
R=golang-dev, r, iant
CC=golang-dev
https://golang.org/cl/12805045
Update #5000
Should reduce the flakiness a little. Malloc counting is important
to general testing but not to the build dashboard, which uses -short.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/12866047
See issue 4949 for a full explanation.
Allocs go from 1 to zero in the non-addressable case.
Fixes#4949.
BenchmarkInterfaceBig 90 14 -84.01%
BenchmarkInterfaceSmall 14 14 +0.00%
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12646043
you do reflect.call with too big an argument list.
Not worth the hassle.
Fixes#6023Fixes#6033
R=golang-dev, bradfitz, dave
CC=golang-dev
https://golang.org/cl/12485043
This is required to properly unwind reflect.methodValueCall/makeFuncStub.
Fixes#5954.
Stats for 'go install std':
61849 total INSTCALL
24655 currently have ArgSize metadata
27278 have ArgSize metadata with this change
godoc size before: 11351888, after: 11364288
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12163043
It changes an exported API, and breaks the build.
««« original CL description
reflect: use unsafe.Pointer in StringHeader and SliceHeader
Relates to issue 5193.
R=r
CC=golang-dev
https://golang.org/cl/8363045
»»»
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/8357051
This CL also replaces similar loops in other stdlib
package tests with calls to AllocsPerRun.
Fixes#4461.
R=minux.ma, rsc
CC=golang-dev
https://golang.org/cl/7002055
The spec mostly uses the term embedded.
It's too late to change the field name but at least fix the docs.
Fixes#4514.
R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/7235080
The new garbage collector (CL 6114046) may find the fake *[]byte value
and interpret its contents as bytes rather than as potential pointers.
This may lead the garbage collector to free memory blocks that
shouldn't be freed.
R=dvyukov, rsc, dave, minux.ma, remyoudompheng, iant
CC=golang-dev
https://golang.org/cl/7000059
The existing algorithm did not properly propagate the type
count from one level to the next, and as a consequence it
missed collisions.
Properly propagate multiplicity (count) information to the
next level.
benchmark old ns/op new ns/op delta
BenchmarkFieldByName1 182 180 -1.10%
BenchmarkFieldByName2 6273 6183 -1.43%
BenchmarkFieldByName3 49267 46784 -5.04%
Fixes#4355.
R=rsc
CC=golang-dev
https://golang.org/cl/6821094
In order to add these, we need to be able to find references
to such types that already exist in the binary. To do that, introduce
a new linker section holding a list of the types corresponding to
arrays, chans, maps, and slices.
To offset the storage cost of this list, and to simplify the code,
remove the interface{} header from the representation of a
runtime type. It was used in early versions of the code but was
made obsolete by the kind field: a switch on kind is more efficient
than a type switch.
In the godoc binary, removing the interface{} header cuts two
words from each of about 10,000 types. Adding back the list of pointers
to array, chan, map, and slice types reintroduces one word for
each of about 500 types. On a 64-bit machine, then, this CL *removes*
a net 156 kB of read-only data from the binary.
This CL does not include the needed support for precise garbage
collection. I have created issue 4375 to track that.
This CL also does not set the 'algorithm' - specifically the equality
and copy functions - for a new array correctly, so I have unexported
ArrayOf for now. That is also part of issue 4375.
Fixes#2339.
R=r, remyoudompheng, mirtchovski, iant
CC=golang-dev
https://golang.org/cl/6572043
The old code worked with gc, I assume because the linker
unified identical strings, but it failed with gccgo.
R=rsc
CC=gobot, golang-dev
https://golang.org/cl/6826063
