It was making the unsound assumption that cgn==nil => v is one
of {Global,Function,Const,Capture} to avoid checking v's type,
which is what it now does. This caused more expensive
constraints to be generated, which is suboptimal though not
wrong exactly.
In one benchmark, this change reduces the number of complex
constraints by about 23% of loads and 53% of stores, and
increases the number of (simple) copy constraints by about 5%.
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/106940043
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
This optimization reduces solve time (typically >90% of the
total) by about 78% when analysing real programs. It also
makes the solver 100% deterministic since all iterations are
ordered.
Also:
- remove unnecessary nodeid parameter to solve() method.
- don't add a fieldInfo for singleton tuples (cosmetic fix).
- inline+simplify "worklist" type.
- replace "constraintset" type by a slice.
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/95240043
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
Programs such as this cause the PtrTo solver to attempt to
enumerate an infinite set of types {T, *T, ..., *******T, etc}.
t := reflect.TypeOf(T{})
for {
t = reflect.PtrTo(t)
}
The fix is to bound the depth of reflectively created types at
about 4 map/chan/slice/pointer constructors.
+ test.
LGTM=gri
R=gri
CC=crawshaw, golang-codereviews
https://golang.org/cl/102030044
Existing tools use the default value of zero; their behaviour is unchanged.
(*Config).ParseFile is used only from tests.
LGTM=crawshaw, rsc, gri
R=crawshaw, gri, rsc
CC=golang-codereviews
https://golang.org/cl/79290044
This change renumbers nodes so that addressable ones
(that may appear in a points-to set) all have lower
numbers than non-addressable ones----initially at least:
reflection, SetFinalizer, etc add new nodes during
solving.
This improves the efficiency of sparse PTS
representations (to be added later). The largest int in
a PTS is now about 20% of the previous max.
Overview:
- move constraint stuff into constraint.go.
- add two methods to constraint:
(1) renumber(): renumbers all nodeids. The
implementations are very repetitive but simple. I
thought hard about other ways (mixins, reflection)
but decided this one was fine.
(2) indirect(): report the set of nodeids whose
points-to relations depend on the solver, not just
the initial constraint graph.
(This method is currently unused and is logically
part of a forthcoming change to implement PE/LE
presolver optimizations. (Perhaps I should comment
it out/remove it for now.)
- split up the population of the intrinsics map by file.
- delete analysis.probes (unused field)
- remove state="..." from panic message; unnecessary.
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/73320043
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
This is to avoid an internal error in pointer analysis from
bringing down a long-lived application such as godoc.
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/68930046
1) We remove context sensitivity from API. The pointer analysis is
not sufficiently context-sensitive for the context information to
be worth exposing. (The actual analysis precision still benefits
from being context-sensitive, though.) Since all clients would
discard the context info, we now do that for them.
2) Make the graph doubly-linked. Edges are now shared by the Nodes
at both ends of the edge so it's possible to navigate more easily
(e.g. to the callers).
3) Graph and Node are now concrete, not interfaces.
Less code in every file!
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/66460043
Previously, each {Indirect,}Query would return a set of Pointers, one per context; now it returns (at most) one Pointer combining information from all contexts.
The old API was more faithful to the implementation concepts, but the analysis is not sufficiently context-sensitive that it makes sense: all existing clients simply throw away the context information---so now we do that for them.
(I may remove the context-sensitivity from the callgraph too, but I'll benchmark that first to see if it reduces precision.)
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/66130044
Observation: not all alias facts are interesting.
- A channel-peers query also cares about pointers of kind chan.
- An oracle "points-to" query on an expression of kind map
only cares about maps.
- We always care about func, interface and reflect.Value,
since they're needed for sound analysis of dynamic dispatch.
We needn't bother collecting alias information for
uninteresting pointers, and this massively reduces the number
of labels flowing in to the constraint system.
The only constraints that create new labels are addressOf
and offsetAddr; both are now selectively emitted by type.
We compute the set of type kinds to track, based on the
{Indirect,}Query types. (We could enable tracking at an
even finer grain if we want.)
This requires that we can see all the {Indirect,}Query
value types a priori, which is not the case for the PrintCalls
mechanism used in the tests, so I have rewritten the latter
to use {Indirect,}Query instead.
This reduces the solver-phase time for the entire standard
library and tests from >8m to <2m. Similar speedups are
obtained on small and medium-sized programs.
Details:
- shouldTrack inspects the flattened form of a type to see if
it contains fields we must track. It memoizes the result.
- added precondition checks to (*Config).Add{,Indirect}Query.
- added (*ssa.Program).LookupMethod convenience method.
- added Example of how to use the Query mechanism.
- removed code made dead by a recent invariant:
the only pointerlike Const value is nil.
- don't generate constraints for any functions in "reflect".
(we had forgotten to skip synthetic wrappers too).
- write PTA warnings to the log.
- add annotations for more intrinsics.
LGTM=gri, crawshaw
R=crawshaw, gri
CC=golang-codereviews
https://golang.org/cl/62540043
Method-set caching is now performed externally using a MethodSetCache (if desired), not by the Types themselves.
This a minor deoptimization due to the extra maps, but avoids a situation in which method-sets are computed and frozen prematurely. (See b/7114)
LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/61430045
This is (a) more efficient and (b) avoids the need for
constant error handling, since buffer writes can't fail.
Also:
- added WriteFunction and WritePackage functions,
similar to types.WriteFoo.
- *Function and *Package now implement io.WriterTo.
LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/57930044
CL 49530047 made the (over-)simplifying assumption that the
Path of an ad-hoc (Created) package should default to its
Name, i.e. package declaration.
With this change, the Name is still always computed from the
package declaration (by go/types) but the Path may be
specified by the loader.Config. If "", the value of the Name
is used, which is not globally unique.
R=gri, axwalk
CC=golang-codereviews
https://golang.org/cl/55180043
Was: Now:
call.Graph callgraph.Graph
call.GraphNode callgraph.Node
call.Edge callgraph.Edge
Though call.Graph was cute, the original naming was a mistake:
'call' is too useful a var name to waste on a package.
R=gri, crawshaw
CC=golang-codereviews
https://golang.org/cl/53190043
Alan Donovan
Robert Griesemer