Make it clear that IsValid checks that we have valid
reflect.Value and not the value of `v`
fixes#34152
Change-Id: Ib3d359eeb3a82bf733b9ed17c777fc4c143bc29c
Reviewed-on: https://go-review.googlesource.com/c/go/+/193841
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Right now we generate hash functions for all types, just in case they
are used as map keys. That's a lot of wasted effort and binary size
for types which will never be used as a map key. Instead, generate
hash functions only for types that we know are map keys.
Just doing that is a bit too simple, since maps with an interface type
as a key might have to hash any concrete key type that implements that
interface. So for that case, implement hashing of such types at
runtime (instead of with generated code). It will be slower, but only
for maps with interface types as keys, and maybe only a bit slower as
the aeshash time probably dominates the dispatch time.
Reorg where we keep the equals and hash functions. Move the hash function
from the key type to the map type, saving a field in every non-map type.
That leaves only one function in the alg structure, so get rid of that and
just keep the equal function in the type descriptor itself.
cmd/go now has 10 generated hash functions, instead of 504. Makes
cmd/go 1.0% smaller. Update #6853.
Speed on non-interface keys is unchanged. Speed on interface keys
is ~20% slower:
name old time/op new time/op delta
MapInterfaceString-8 23.0ns ±21% 27.6ns ±14% +20.01% (p=0.002 n=10+10)
MapInterfacePtr-8 19.4ns ±16% 23.7ns ± 7% +22.48% (p=0.000 n=10+8)
Change-Id: I7c2e42292a46b5d4e288aaec4029bdbb01089263
Reviewed-on: https://go-review.googlesource.com/c/go/+/191198
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
When calling a function obtained from reflect.Value.Method (or
MethodByName), we copy the arguments from the caller frame, which
does not include the receiver, to a new frame to call the actual
method, which does include the receiver. Here we need to align
the first (non-receiver) argument. As the receiver is pointer
sized, it is generally naturally aligned, except on amd64p32,
where the argument can have larger alignment, and this aligning
becomes necessary.
Fixes#33628.
Change-Id: I5bea0e20173f06d1602c5666d4f334e3d0de5c1e
Reviewed-on: https://go-review.googlesource.com/c/go/+/190297
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
There is a subtle distinction between a value
*being* the zero value vs being *equal to* the zero value.
This was discussed at length in #31450.
Using "a zero value" in the docs suggests that there may
be more than zero value. That is possible on the "equal to
zero value" reading, but not the "is zero" reading that we
selected for the semantics of IsZero.
This change attempts to prevent any confusion on this front by
switching to "the zero value" in the documentation.
And while we're here, eliminate a double-space.
(Darn macbook keyboards.)
Change-Id: Iaa02ba297438793f5a90be9919a4d53baef92f8e
Reviewed-on: https://go-review.googlesource.com/c/go/+/182617
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Before this CL we used to panic with "nil pointer dereference" because
the value we're calling assignTo on is the zero Value. Provide a better
error message.
Fixes#28748
Change-Id: I7dd4c9e30b599863664d91e78cc45878d8b0052e
Reviewed-on: https://go-review.googlesource.com/c/go/+/175440
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Instead of requiring exact type match, allow assignment conversions
(those conversions allowed in the language spec without a cast) on the
returned values.
Particularly useful when the type being returned is an interface type,
but the Value actually returned is a concrete value implementing that
type (as it is tricky to return a Value which has interface type).
RELNOTE=y
Fixes#28761
Change-Id: I69eef07ca51690b2086dfa1eb549db5e4724c657
Reviewed-on: https://go-review.googlesource.com/c/go/+/174531
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
The spec carefully and consistently uses "key" and "element"
as map terminology. The implementation, not so much.
This change attempts to make the implementation consistently
hew to the spec's terminology. Beyond consistency, this has
the advantage of avoid some confusion and naming collisions,
since v and value are very generic and commonly used terms.
I believe that I found all everything, but there are a lot of
non-obvious places for these to hide, and grepping for them is hard.
Hopefully this change changes enough of them that we will start using
elem going forward. Any remaining hidden cases can be removed ad hoc
as they are discovered.
The only externally-facing part of this change is in package reflect,
where there is a minor doc change and a function parameter name change.
Updates #27167
Change-Id: I2f2d78f16c360dc39007b9966d5c2046a29d3701
Reviewed-on: https://go-review.googlesource.com/c/go/+/174523
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
mustBe was barely over budget, so manually inlining the first flag.kind
call is enough. Add a TODO to reverse that in the future, once the
compiler gets better.
mustBeExported and mustBeAssignable were over budget by a larger amount,
so add slow path functions instead. This is the same strategy used in
the sync package for common methods like Once.Do, for example.
Lots of exported reflect.Value methods call these assert-like unexported
methods, so avoiding the function call overhead in the common case does
shave off a percent from most exported APIs.
Finally, add the methods to TestIntendedInlining.
While at it, replace a couple of uses of the 0 Kind with its descriptive
name, Invalid.
name old time/op new time/op delta
Call-8 68.0ns ± 1% 66.8ns ± 1% -1.81% (p=0.000 n=10+9)
PtrTo-8 8.00ns ± 2% 7.83ns ± 0% -2.19% (p=0.000 n=10+9)
Updates #7818.
Change-Id: Ic1603b640519393f6b50dd91ec3767753eb9e761
Reviewed-on: https://go-review.googlesource.com/c/go/+/166462
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
We are copying the results to uninitialized stack space. Write
barrier is not needed.
Fixes#30041.
Change-Id: Ia91d74dbafd96dc2bd92de0cb479808991dda03e
Reviewed-on: https://go-review.googlesource.com/c/160737
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
UnsafePointer is a valid type kind to call IsNil on.
Fixes#29381
Change-Id: Iaf65d582c67f4be52cd1885badf40f174920500b
Reviewed-on: https://go-review.googlesource.com/c/155797
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Currently, package runtime contains the definition of reflect.call,
even though it's just a jump to runtime.reflectcall. This "push"
symbol is confusing, since it's not clear where the definition of
reflect.call comes from when you're in the reflect package.
Replace this with a "pull" symbol: the runtime now defines only
runtime.reflectcall and package reflect uses a go:linkname to access
this symbol directly. This makes it clear where reflect.call is coming
from without any spooky action at a distance and eliminates all of the
definitions of reflect.call in the runtime.
Change-Id: I3ec73cd394efe9df8d3061a57c73aece2e7048dd
Reviewed-on: https://go-review.googlesource.com/c/148657
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
During a call to a reflect-generated function or method (via
makeFuncStub or methodValueCall), when should we scan the return
values?
When we're starting a reflect call, the space on the stack for the
return values is not initialized yet, as it contains whatever junk was
on the stack of the caller at the time. The return space must not be
scanned during a GC.
When we're finishing a reflect call, the return values are
initialized, and must be scanned during a GC to make sure that any
pointers in the return values are found and their referents retained.
When the GC stack walk comes across a reflect call in progress on the
stack, it needs to know whether to scan the results or not. It doesn't
know the progress of the reflect call, so it can't decide by
itself. The reflect package needs to tell it.
This CL adds another slot in the frame of makeFuncStub and
methodValueCall so we can put a boolean in there which tells the
runtime whether to scan the results or not.
This CL also adds the args length to reflectMethodValue so the
runtime can restrict its scanning to only the args section (not the
results) if the reflect package says the results aren't ready yet.
Do a delicate dance in the reflect package to set the "results are
valid" bit. We need to make sure we set the bit only after we've
copied the results back to the stack. But we must set the bit before
we drop reflect's copy of the results. Otherwise, we might have a
state where (temporarily) no one has a live copy of the results.
That's the state we were observing in issue #27695 before this CL.
The bitmap used by the runtime currently contains only the args.
(Actually, it contains all the bits, but the size is set so we use
only the args portion.) This is safe for early in a reflect call, but
unsafe late in a reflect call. The test issue27695.go demonstrates
this unsafety. We change the bitmap to always include both args
and results, and decide at runtime which portion to use.
issue27695.go only has a test for method calls. Function calls were ok
because there wasn't a safepoint between when reflect dropped its copy
of the return values and when the caller is resumed. This may change
when we introduce safepoints everywhere.
This truncate-to-only-the-args was part of CL 9888 (in 2015). That
part of the CL fixed the problem demonstrated in issue27695b.go but
introduced the problem demonstrated in issue27695.go.
TODO, in another CL: simplify FuncLayout and its test. stack return
value is now identical to frametype.ptrdata + frametype.gcdata.
Fixes#27695
Change-Id: I2d49b34e34a82c6328b34f02610587a291b25c5f
Reviewed-on: https://go-review.googlesource.com/137440
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Fix the code to use write barriers on heap memory, and no
write barriers on stack memory.
These errors were discoverd as part of fixing #27695. They may
have something to do with that issue, but hard to be sure.
The core cause is different, so this fix is a separate CL.
Update #27695
Change-Id: Ib005f6b3308de340be83c3d07d049d5e316b1e3c
Reviewed-on: https://go-review.googlesource.com/137438
Reviewed-by: Austin Clements <austin@google.com>
Example of use:
iter := reflect.ValueOf(m).MapRange()
for iter.Next() {
k := iter.Key()
v := iter.Value()
...
}
See issue golang/go#11104
Q. Are there any benchmarks that would exercise the new calls to
copyval in existing code?
Change-Id: Ic469fcab5f1d9d853e76225f89bde01ee1d36e7a
Reviewed-on: https://go-review.googlesource.com/33572
Reviewed-by: Keith Randall <khr@golang.org>
On the API level this is just an update of the documentation to match
the current spec more closely.
On the implementation side, this is a rename of various unexported names.
For #22005.
Change-Id: Ie5ae32f3b10f003805240efcceab3d0fd373cd51
Reviewed-on: https://go-review.googlesource.com/112717
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
If the type of Type is known to be *rtype than the common
function is a no-op and does not need to be called.
name old time/op new time/op delta
New 31.0ns ± 5% 30.2ns ± 4% -2.74% (p=0.008 n=20+20)
Change-Id: I5d00346dbc782e34c530166d1ee0499b24068b51
Reviewed-on: https://go-review.googlesource.com/96115
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
It's not safe to do p+x with unsafe if that would point past the
end of the object. (Valid in C, not safe in Go.)
Pass a "whySafe" reason (compiled away) to explain at each
call site why it's safe.
Fixes#21733.
Change-Id: I5da8c25bde66f5c9beac232f2135dcab8e8bf3b1
Reviewed-on: https://go-review.googlesource.com/80738
Reviewed-by: Austin Clements <austin@google.com>
Call is meant to mirror the language semantics, which allow:
var r io.ReadWriter
f := func(io.Reader){}
f(r)
even though the conversion from io.ReadWriter to io.Reader is
being applied to a nil interface. This is different from an explicit
conversion:
_ = r.(io.Reader)
f(r.(io.Reader))
Both of those lines panic, but the implicit conversion does not.
By using E2I, which is the implementation of the explicit conversion,
the reflect.Call equivalent of f(r) was inadvertently panicking.
Avoid the panic.
Fixes#22143.
Change-Id: I6b2f5b808e0cd3b89ae8bc75881e307bf1c25558
Reviewed-on: https://go-review.googlesource.com/80736
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
All of these had a return or break in the else body, so flipping the
condition means we can unindent and simplify.
Change-Id: If93e97504480d18a0dac3f2c8ffe57ab8bcb929c
Reviewed-on: https://go-review.googlesource.com/74190
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This somewhat mirrors the special case behavior of the copy built-in.
Fixes#22215
Change-Id: Ic353003ad3de659d3a6b4e9d97295b42510f3bf7
Reviewed-on: https://go-review.googlesource.com/70431
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Currently, methods are sorted by name. This happens to guarantee that
exported ASCII methods appear before non-exported ASCII methods, but
this breaks down when Unicode method names are considered.
Type.Method already accounts for this by always indexing into the
slice returned by exportedMethods. This CL makes Value.Method do the
same.
Fixes#22073.
Change-Id: I9bfc6bbfb7353e0bd3c439a15d1c3da60d16d209
Reviewed-on: https://go-review.googlesource.com/66770
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
The reflect API normally grants only read-only access to non-exported
fields, but it specially handles non-exported embedded fields so that
users can still fully access promoted fields and methods. For example,
if v.Field(i) refers to a non-exported embedded field, it would be
limited to RO access. But if v.Field(i).Field(j) is an exported field,
then the resulting Value will have full access.
However, the way this was implemented allowed other operations to be
interspersed between the Field calls, which could grant inappropriate
access.
Relatedly, Elem() is safe to use on pointer-embeddings, but it was
also being allowed on embeddings of interface types. This is
inappropriate because it could allow accessing methods of the dynamic
value's complete method set, not just those that were promoted via the
interface embedding.
Fixes#22031.
Fixes#22053.
Change-Id: I9db9be88583f1c1d80c1b4705a76f23a4379182f
Reviewed-on: https://go-review.googlesource.com/66331
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
If a function with nonzero frame but zero-sized return value is
Call'd, we may write a past-the-end pointer in preparing the
return Values. Fix by return the zero value for zero-sized
return value.
Fixes#21717.
Change-Id: I5351cd86d898467170a888b4c3fc9392f0e7aa3b
Reviewed-on: https://go-review.googlesource.com/60811
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
We don't use it any more, remove it.
Change-Id: I76ce1a4c2e7048fdd13a37d3718b5abf39ed9d26
Reviewed-on: https://go-review.googlesource.com/44474
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Just use fun[0]==0 to indicate a bad itab.
Change-Id: I28ecb2d2d857090c1ecc40b1d1866ac24a844848
Reviewed-on: https://go-review.googlesource.com/44473
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Keep itabs in a growable hash table.
Use a simple open-addressable hash table, quadratic probing, power
of two sized.
Synchronization gets a bit more tricky. The common read path now
has two atomic reads, one to get the table pointer and one to read
the entry out of the table.
I set the max load factor to 75%, kind of arbitrarily. There's a
space-speed tradeoff here, and I'm not sure where we should land.
Because we use open addressing the itab.link field is no longer needed.
I'll remove it in a separate CL.
Fixes#20505
Change-Id: Ifb3d9a337512d6cf968c1fceb1eeaf89559afebf
Reviewed-on: https://go-review.googlesource.com/44472
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Following the spec clarification in CL 40393, copy that text
to reflect docs to state that the initial capacity of MakeMapWithSize
is a hint/approximate.
Fixes#19903
Change-Id: I6b3315b8183cafaa61fbb2839a4e42b76fd71544
Reviewed-on: https://go-review.googlesource.com/46270
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
v is not a pointer receiver, and v.typ isn't used in the lines below.
The assignment is dead. Remove it.
Keep the comment, as it refers to the whole case block and not just the
removed line.
Change-Id: Icb2d20c287d9a41bf620ebe5cdec764cd84178a7
Reviewed-on: https://go-review.googlesource.com/43134
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Providing size hint when creating a map allows avoiding re-allocating
underlying data structure if we know how many elements are going to
be inserted. This can be used for example during decoding maps in
gob.
Fixes#19599
Change-Id: I108035fec29391215d2261a73eaed1310b46bab1
Reviewed-on: https://go-review.googlesource.com/38335
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
reflect.callReflect heap-allocates a stack frame and then constructs
pointers to the arguments and result areas of that frame. However, if
there are no results, the results pointer will point past the end of
the frame allocation. If there are also no arguments, the arguments
pointer will also point past the end of the frame allocation. If the
GC observes either these pointers, it may panic.
Fix this by not constructing these pointers if these areas of the
frame are empty.
This adds a test of calling no-argument/no-result methods via reflect,
since nothing in std did this before. However, it's quite difficult to
demonstrate the actual failure because it depends on both exact
allocation patterns and on GC scanning the goroutine's stack while
inside one of the typedmemmovepartial calls.
I also audited other uses of typedmemmovepartial and
memclrNoHeapPointers in reflect, since these are the most susceptible
to this. These appear to be the only two cases that can construct
out-of-bounds arguments to these functions.
Fixes#19724.
Change-Id: I4b83c596b5625dc4ad0567b1e281bad4faef972b
Reviewed-on: https://go-review.googlesource.com/38736
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The chanrecv funcs don't use it at all. The chansend ones do, but the
element type is now part of the hchan struct, which is already a
parameter.
hchan can be nil in chansend when sending to a nil channel, so when
instrumenting we must copy to the stack to be able to read the channel
type.
name old time/op new time/op delta
ChanUncontended 6.42µs ± 1% 6.22µs ± 0% -3.06% (p=0.000 n=19+18)
Initially found by github.com/mvdan/unparam.
Fixes#19591.
Change-Id: I3a5e8a0082e8445cc3f0074695e3593fd9c88412
Reviewed-on: https://go-review.googlesource.com/38351
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Make the documentation more explicit that it is not safe to directly
compare Value. Get straight to the point on how to do it correctly.
Updates #18871
Change-Id: I2aa3253f779636b2f72a1aae8c9bb45d3c32c902
Reviewed-on: https://go-review.googlesource.com/36018
Reviewed-by: Keith Randall <khr@golang.org>
For #18130.
f8b4123613 [dev.typealias] spec: use term 'embedded field' rather than 'anonymous field'
9ecc3ee252 [dev.typealias] cmd/compile: avoid false positive cycles from type aliases
49b7af8a30 [dev.typealias] reflect: add test for type aliases
9bbb07ddec [dev.typealias] cmd/compile, reflect: fix struct field names for embedded byte, rune
43c7094386 [dev.typealias] reflect: fix StructOf use of StructField to match StructField docs
9657e0b077 [dev.typealias] cmd/doc: update for type alias
de2e5459ae [dev.typealias] cmd/compile: declare methods after resolving receiver type
9259f3073a [dev.typealias] test: match gccgo error messages on alias2.go
5d92916770 [dev.typealias] cmd/compile: change Func.Shortname to *Sym
a7c884efc1 [dev.typealias] go/internal/gccgoimporter: support for type aliases
5802cfd900 [dev.typealias] cmd/compile: export/import test cases for type aliases
d7cabd40dd [dev.typealias] go/types: clarified doc string
cc2dcce3d7 [dev.typealias] cmd/compile: a few better comments related to alias types
5c160b28ba [dev.typealias] cmd/compile: improved error message for cyles involving type aliases
b2386dffa1 [dev.typealias] cmd/compile: type-check type alias declarations
ac8421f9a5 [dev.typealias] cmd/compile: various minor cleanups
f011e0c6c3 [dev.typealias] cmd/compile, go/types, go/importer: various alias related fixes
49de5f0351 [dev.typealias] cmd/compile, go/importer: define export format and implement importing of type aliases
5ceec42dc0 [dev.typealias] go/types: export TypeName.IsAlias so clients can use it
aa1f0681bc [dev.typealias] go/types: improved Object printing
c80748e389 [dev.typealias] go/types: remove some more vestiges of prior alias implementation
80d8b69e95 [dev.typealias] go/types: implement type aliases
a917097b5e [dev.typealias] go/build: add go1.9 build tag
3e11940437 [dev.typealias] cmd/compile: recognize type aliases but complain for now (not yet supported)
e0a05c274a [dev.typealias] cmd/gofmt: added test cases for alias type declarations
2e5116bd99 [dev.typealias] go/ast, go/parser, go/printer, go/types: initial type alias support
Change-Id: Ia65f2e011fd7195f18e1dce67d4d49b80a261203
Will also fix type aliases.
Fixes#17766.
For #18130.
Change-Id: I9e1584d47128782152e06abd0a30ef423d5c30d2
Reviewed-on: https://go-review.googlesource.com/35732
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
When traceback sees reflect.makeFuncStub (or reflect.methodValueCall)
on the stack, it expects to be able to get the *reflect.makeFuncImpl
(or *reflect.methodValue) for that call from the first outgoing
argument slot of makeFuncStub/methodValueCall.
However, currently this object isn't necessarily kept live across
makeFuncStub. This means it may get garbage collected while in a
reflect call and reused for something else. If we then try to
traceback, the runtime will see a corrupted makeFuncImpl object and
panic. This was not a problem in previous releases because we always
kept arguments live across the whole function. This became a problem
when we stopped doing this.
Fix this by using reflect.KeepAlive to keep the
makeFuncImpl/methodValue live across all of callReflect/callMethod,
which in turn keeps it live as long as makeFuncStub/methodValueCall
are on the stack.
Fixes#18635.
Change-Id: I91853efcf17912390fddedfb0230648391c33936
Reviewed-on: https://go-review.googlesource.com/35151
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Since barrier-less memclr is only safe in very narrow circumstances,
this commit renames memclr to avoid accidentally calling memclr on
typed memory. This can cause subtle, non-deterministic bugs, so it's
worth some effort to prevent. In the near term, this will also prevent
bugs creeping in from any concurrent CLs that add calls to memclr; if
this happens, whichever patch hits master second will fail to compile.
This also adds the other new memclr variants to the compiler's
builtin.go to minimize the churn on that binary blob. We'll use these
in future commits.
Updates #17503.
Change-Id: I00eead049f5bd35ca107ea525966831f3d1ed9ca
Reviewed-on: https://go-review.googlesource.com/31369
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
The hybrid barrier requires distinguishing typed and untyped memory
even when zeroing because the *current* contents of the memory matters
even when overwriting.
This commit introduces runtime.typedmemclr and runtime.memclrHasPointers
as a typed memory clearing functions parallel to runtime.typedmemmove.
Currently these simply call memclr, but with the hybrid barrier we'll
need to shade any pointers we're overwriting. These will provide us
with the necessary hooks to do so.
Updates #17503.
Change-Id: I74478619f8907825898092aaa204d6e4690f27e6
Reviewed-on: https://go-review.googlesource.com/31366
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Currently reflectcall has a subtle dance with write barriers where the
assembly code copies the result values from the stack to the in-heap
argument frame without write barriers and then calls into the runtime
after the fact to invoke the necessary write barriers.
For the hybrid barrier (and for ROC), we need to switch to a
*pre*-write write barrier, which is very difficult to do with the
current setup. We could tie ourselves in knots of subtle reasoning
about why it's okay in this particular case to have a post-write write
barrier, but this commit instead takes a different approach. Rather
than making things more complex, this simplifies reflection calls so
that the argument copy is done in Go using normal bulk write barriers.
The one difficulty with this approach is that calling into Go requires
putting arguments on the stack, but the call* functions "donate" their
entire stack frame to the called function. We can get away with this
now because the copy avoids using the stack and has copied the results
out before we clobber the stack frame to call into the write barrier.
The solution in this CL is to call another function, passing arguments
in registers instead of on the stack, and let that other function
reserve more stack space and setup the arguments for the runtime.
This approach seemed to work out the best. I also tried making the
call* functions reserve 32 extra bytes of frame for the write barrier
arguments and adjust SP up by 32 bytes around the call. However, even
with the necessary changes to the assembler to correct the spdelta
table, the runtime was still having trouble with the frame layout (and
the changes to the assembler caused many other things that do strange
things with the SP to fail to assemble). The approach I took doesn't
require any funny business with the SP.
Updates #17503.
Change-Id: Ie2bb0084b24d6cff38b5afb218b9e0534ad2119e
Reviewed-on: https://go-review.googlesource.com/31655
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Introduce and start using nameOff for two encoded names. This pair
of changes is best done together because the linker's method decoder
expects the method layouts to match.
Precursor to converting all existing name and *string fields to
nameOff.
linux/amd64:
cmd/go: -45KB (0.5%)
jujud: -389KB (0.6%)
linux/amd64 PIE:
cmd/go: -170KB (1.4%)
jujud: -1.5MB (1.8%)
For #6853.
Change-Id: Ia044423f010fb987ce070b94c46a16fc78666ff6
Reviewed-on: https://go-review.googlesource.com/21396
Reviewed-by: Ian Lance Taylor <iant@golang.org>
cmd and runtime were handled separately, and I'm intentionally skipped
syscall. This is the rest of the standard library.
CL generated mechanically with github.com/mdempsky/unconvert.
Change-Id: I9e0eff886974dedc37adb93f602064b83e469122
Reviewed-on: https://go-review.googlesource.com/22104
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This CL introduces the typeOff type and a lookup method of the same
name that can turn a typeOff offset into an *rtype.
In a typical Go binary (built with buildmode=exe, pie, c-archive, or
c-shared), there is one moduledata and all typeOff values are offsets
relative to firstmoduledata.types. This makes computing the pointer
cheap in typical programs.
With buildmode=shared (and one day, buildmode=plugin) there are
multiple modules whose relative offset is determined at runtime.
We identify a type in the general case by the pair of the original
*rtype that references it and its typeOff value. We determine
the module from the original pointer, and then use the typeOff from
there to compute the final *rtype.
To ensure there is only one *rtype representing each type, the
runtime initializes a typemap for each module, using any identical
type from an earlier module when resolving that offset. This means
that types computed from an offset match the type mapped by the
pointer dynamic relocations.
A series of followup CLs will replace other *rtype values with typeOff
(and name/*string with nameOff).
For types created at runtime by reflect, type offsets are treated as
global IDs and reference into a reflect offset map kept by the runtime.
darwin/amd64:
cmd/go: -57KB (0.6%)
jujud: -557KB (0.8%)
linux/amd64 PIE:
cmd/go: -361KB (3.0%)
jujud: -3.5MB (4.2%)
For #6853.
Change-Id: Icf096fd884a0a0cb9f280f46f7a26c70a9006c96
Reviewed-on: https://go-review.googlesource.com/21285
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change removes a lot of dead code. Some of the code has never been
used, not even when it was first commited. The rest shouldn't have
survived refactors.
This change doesn't remove unused routines helpful for debugging, nor
does it remove code that's used in commented out blocks of code that are
only unused temporarily. Furthermore, unused constants weren't removed
when they were part of a set of constants from specifications.
One noteworthy omission from this CL are about 1000 lines of unused code
in cmd/fix, 700 lines of which are the typechecker, which hasn't been
used ever since the pre-Go 1 fixes have been removed. I wasn't sure if
this code should stick around for future uses of cmd/fix or be culled as
well.
Change-Id: Ib714bc7e487edc11ad23ba1c3222d1fd02e4a549
Reviewed-on: https://go-review.googlesource.com/20926
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Create a byte encoding designed for static Go names.
It is intended to be a compact representation of a name
and optional tag data that can be turned into a Go string
without allocating, and describes whether or not it is
exported without unicode table.
The encoding is described in reflect/type.go:
// The first byte is a bit field containing:
//
// 1<<0 the name is exported
// 1<<1 tag data follows the name
// 1<<2 pkgPath *string follow the name and tag
//
// The next two bytes are the data length:
//
// l := uint16(data[1])<<8 | uint16(data[2])
//
// Bytes [3:3+l] are the string data.
//
// If tag data follows then bytes 3+l and 3+l+1 are the tag length,
// with the data following.
//
// If the import path follows, then ptrSize bytes at the end of
// the data form a *string. The import path is only set for concrete
// methods that are defined in a different package than their type.
Shrinks binary sizes:
cmd/go: 164KB (1.6%)
jujud: 1.0MB (1.5%)
For #6853.
Change-Id: I46b6591015b17936a443c9efb5009de8dfe8b609
Reviewed-on: https://go-review.googlesource.com/20968
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
And fix the wrong comment.
Initially found this because the comment was wrong about the possible
values. Then noticed that there doesn't seem to be any reason to use
uintptr over SelectDir.
Change-Id: I4f9f9640e49d89e558ed00bd99e57dab890785f5
Reviewed-on: https://go-review.googlesource.com/20655
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
