Command set:
- what: an extremely fast query that parses a single
file and returns the AST stack, package name and the
set of query modes that apply to the current selection.
Intended for GUI tools that need to grey out UI elements.
- definition: shows the definition of an identifier.
- pointsto: the PTA features of 'describe' have been split
out into their own command.
- describe: with PTA stripped out, the cost is now bounded by
type checking.
Performance:
- The importer.Config.TypeCheckFuncBodies predicate supports
setting the 'IgnoreFuncBodies' typechecker flag on a
per-package basis. This means we can load dependencies from
source more quickly if we only need exported types.
(We avoid gcimport data because it may be absent or stale.)
This also means we can run type-based queries on packages
that aren't part of the pointer analysis scope. (Yay.)
- Modes that require only type analysis of the query package
run a "what" query first, and restrict their analysis scope
to just that package and its dependencies (sans func
bodies), making them much faster.
- We call newOracle not oracle.New in Query, so that the
'needs' bitset isn't ignored (oops!). This makes the
non-PTA queries faster.
Also:
- removed vestigial timers junk.
- pos.go: existing position utilties split out into own file.
Added parsePosFlag utility.
- numerous cosmetic tweaks.
+ very basic tests.
To do in follow-ups:
- sophisticated editor integration of "what".
- better tests.
- refactoring of control flow as described in comment.
- changes to "implements", "describe" commands.
- update design doc + user manual.
R=crawshaw, dominik.honnef
CC=golang-dev, gri
https://golang.org/cl/40630043
reflect.Values may point to tagged objects with
interface type, e.g. x := reflect.ValueOf(new(interface{})).Elem().
We failed to consider this when implementing Elem.
Also, (reflect.Value).Interface() must do one "unboxing"
when it encounters such tagged objects.
i.e., x.Elem().Interface() and x.Interface() are equivalent
in that case.
Also:
- add example of tagged object with interface type.
- untabify (Label).String docstring.
- added tests.
R=crawshaw
CC=golang-dev
https://golang.org/cl/18020044
Since the Go runtime treats it specially, so must the pointer analysis.
Details:
- Combine object.{val,typ} fields into 'data interface{}'.
It may now hold a string, describing an instrinsically
allocated object such as the command-line args.
- extend Label accordingly; add Label.ReflectType() accessor.
Also: document pointer analysis algorithm classification.
R=crawshaw
CC=golang-dev
https://golang.org/cl/14156043
Also: pointer.Analyze now returns a pointer.Result object,
containing the callgraph and the results of ssa.Value queries.
The oracle has been updated to use the new call and pointer APIs.
R=crawshaw, gri
CC=golang-dev
https://golang.org/cl/13915043
Core:
reflect.TypeOf
reflect.ValueOf
reflect.Zero
reflect.Value.Interface
Maps:
(reflect.Value).MapIndex
(reflect.Value).MapKeys
(reflect.Value).SetMapIndex
(*reflect.rtype).Elem
(*reflect.rtype).Key
+ tests:
pointer/testdata/mapreflect.go.
oracle/testdata/src/main/reflection.go.
Interface objects (T, V...) have been renamed "tagged objects".
Abstraction: we model reflect.Value similar to
interface{}---as a pointer that points only to tagged
objects---but a reflect.Value may also point to an "indirect
tagged object", one in which the payload V is of type *T not T.
These are required because reflect.Values can hold lvalues,
e.g. when derived via Field() or Elem(), though we won't use
them till we get to structs and pointers.
Solving: each reflection intrinsic defines a new constraint
and resolution rule. Because of the nature of reflection,
generalizing across types, the resolution rules dynamically
create additional complex constraints during solving, where
previously only simple (copy) constraints were created.
This requires some solver changes:
The work done before the main solver loop (to attach new
constraints to the graph) is now done before each iteration,
in processNewConstraints.
Its loop over constraints is broken into two passes:
the first handles base (addr-of) constraints,
the second handles simple and complex constraints.
constraint.init() has been inlined. The only behaviour that
varies across constraints is ptr()
Sadly this will pessimize presolver optimisations, when we get
there; such is the price of reflection.
Objects: reflection intrinsics create objects (i.e. cause
memory allocations) with no SSA operation. We will represent
them as the cgnode of the instrinsic (e.g. reflect.New), so we
extend Labels and node.data to represent objects as a product
(not sum) of ssa.Value and cgnode and pull this out into its
own type, struct object. This simplifies a number of
invariants and saves space. The ntObject flag is now
represented by obj!=nil; the other flags are moved into
object.
cgnodes are now always recorded in objects/Labels for which it
is appropriate (all but those for globals, constants and the
shared contours for functions).
Also:
- Prepopulate the flattenMemo cache to consider reflect.Value
a fake pointer, not a struct.
- Improve accessors and documentation on type Label.
- @conctypes assertions renamed @types (since dyn. types needn't be concrete).
- add oracle 'describe' test on an interface (missing, an oversight).
R=crawshaw
CC=golang-dev
https://golang.org/cl/13418048
