Also, define ssa:wrapnilchk intrinsic to check and gracefully
fail when a T method is dynamically invoked via a nil *T receiver.
+ Test.
A follow-up CL will add another intrinsic, ssa:memclr.
+ minor cleanups.
LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/101170044
It is easier for clients to recover from panics if the recover block
is always present. Otherwise, the client has to work around the lack
of a recover block by synthesizing a zero value return.
LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://golang.org/cl/87210044
Blocks dominated by "if false" should be retained in the
initial SSA form so they remain visible to subsequent source
code analysis tools.
In any case, true compilers already need a stronger version of
this optimization so they can simplify CFGs such as this:
const x, y = ...
switch x {case y:...}
where a branch is constant but the comparison of constants
does not occur within an expression.
LGTM=gri
R=gri
CC=golang-codereviews, pcc
https://golang.org/cl/101250043
The SSA builder shouldn't be in the business of
interprocedural optimization, especially in the presence of
concurrency.
This causes the instruction count to increase by 0.03%.
LGTM=gri
R=gri, pcc
CC=golang-codereviews
https://golang.org/cl/105020045
Also:
- extend Parent() to all Values and add to interface:
(Builtin/Const/Global => nil; Function => Enclosing)
- hide Function.Enclosing since it's now redundant wrt Parent()
- make (*Function).String robust for synthetics without pkg object
LGTM=gri
R=gri
CC=golang-codereviews, khr
https://golang.org/cl/87580044
Until now, the same Function was used to represent a method
(T)func() and the "method expression" function func(T) formed
from it. So the SSA code for this:
var buf bytes.Buffer
f := Buffer.Bytes
f(buf)
buf.Bytes()
would involve an implicit cast (ChangeType) on line 2.
However, compilers based on go/ssa may want to use different
calling conventions for them, like gccgo does (see issue
7839). This change decouples them by using an anonymous
function called a "thunk", rather like this:
f := func(r *bytes.Buffer) []byte { return r.Bytes() }
Thunks are similar to method wrappers; both are created by
makeWrapper.
"Interface method wrappers" were a special case of thunks for
direct calls (no indirection/fields) of interface methods.
They are now subsumed by thunks and have been deleted. Now
that only the needed thunks are built, we don't need to
populate the concrete method sets of interface types at all,
so (*Program).Method and LookupMethod return nil for them.
This results in a slight reduction in function count (>1%) and
instruction count (<<1%).
Details:
go/ssa:
- API: ChangeType no longer supports func/method conversions.
- API: (*Program).FuncValue now returns nil for abstract
(interface) methods.
- API: (*Function).RelString simplified.
"$bound" is now a suffix not a prefix, and the receiver
type is rendered package-relative.
- API: Function.Object is now defined for all wrappers too.
- API: (*Program).Method and LookupMethod return nil for
abstract methods.
- emitConv no longer permits (non-identical)
Signature->Signature conversions. Added assertion.
- add and use isInterface helper
- sanity: we check packages after Build, not Create, otherwise
cross-package refs might fail.
go/pointer:
- update tests for new function strings.
- pointer_test: don't add non-pointerlike probes to analysis.
(The error was checked, but too late, causing a panic.)
- fixed a minor bug: if a test probe print(x) was the sole
reference to x, no nodes were generated for x.
- (reflect.Type).MethodByName: updated due to ssa API changes.
Also, fixed incorrect testdata/funcreflect.go expectation
for MethodByName on interfaces.
oracle:
- fix for new FuncValue semantics.
- a "pointsto" query on an I.f thunk now returns an error.
Fixesgolang/go#7839
LGTM=gri
R=gri
CC=golang-codereviews, pcc
https://golang.org/cl/93780044
Before, they were named func@line:col which made them easy to find in the source if you know the file, but hard if you don't, and it made tests fragile.
Now, they are named outer$1, outer$2, etc, which makes them
more informative in a UI since "outer" has meaning.
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/65630048
Method Signatures (types.Signatures with a non-nil receiver) behave
like ordinary func Signatures in the hash function/equivalence relation
used by typemap.M, which leads to surprising incomplete traversal
over the type graph if an M is used to remember types already
visited.
This change avoids ever putting method Signatures in a typemap.
% go test -v code.google.com/p/go.tools/go/ssa
now repeatedly shows the exact same number of functions and
instructions.
(We should discuss how to avoid this problem more generally.)
Also:
- recur over the params/results of all the methods of
each type when computing necessary method sets.
- there's no longer any need to treat declarations of unexported
methods as a root for traversal. Added test case.
- enable SourceImports flag in stdlib_test, which was dropped
during a recent refactoring (d'oh).
- doc tweaks
LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/65450043
Alan Donovan
Peter Collingbourne
Robert Griesemer