PackageInfo:
- deleted IsType
- inlined + deleted: ValueOf, TypeCaseVar, ImportSpecPkg
- on failure, TypeOf accessor now returns nil (was: panic)
go/ssa: avoid extra map lookups by using Uses or Defs directly when safe to do so,
and keeping the TypeAndValue around in expr0().
LGTM=gri
R=gri, pcc
CC=golang-codereviews
https://golang.org/cl/107650043
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
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
Revision 0ea4058a1ca3 caused the node numbering to become
sparse, violating a precondition of
(*callgraphResult).toSerial. Now we renumber the callgraph
nodes always, not just the qpos != nil case.
Fixesgolang/go#8171
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/103240044
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
An identifier X in anonymous struct field struct{X} is both a
definition of a field (*Var) and reference to a type
(*TypeName). Now that we have split the map, we can capture
both of these aspects.
Interestingly, every client but one was going to extra effort
to iterate over just the uses or just the defs; this
simplifies them.
Also, fix two bug related to tagless switches:
- An entry was being recorded in the Object map for a piece of
synthetic syntax.
- The "true" identifier was being looked up in the current scope,
which allowed perverse users to locally redefine it. Now
we use the bool (not untyped boolean) constant true, per the
consequent clarification of the spec (issue 7404).
+ tests.
Fixesgolang/go#7276
LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/68270044
If a -pos argument is specified, a 'callgraph' query reports only the
functions within the query package. This produces a far more manageable
amount of information, and because we don't need to package-qualify the
names, the result is easier to read.
Added tests:
- callgraph query with/without -pos
(The test driver was extended to allow "nopos" queries.)
- callers and callees queries don't return wrappers
Also, in go/callgraph:
- (*Node).String, (*Edge).String
- (*Graph).DeleteSyntheticNodes eliminates synthetic wrapper functions,
preserving topology. Used in all four oracle "call*" queries.
- (*Graph).DeleteNode
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/66240044
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
Previously, each word could be a package import path or a
comma-separated list of *.go file names. Now, if the
first word ends with ".go", all words are assumed to be
Go source files. This makes it impossible to specify
two ad-hoc packages from source files, but no-one needs that.
FromArgs also takes a boolean indicating whether tests
are wanted or not.
Also: ssadump: add -test flag to set that boolean.
For the oracle it's always true.
LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/61470047
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
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
The Importer type has been replaced with Config and Program.
Clients populate a Config, directly or more usually via
convenience functions. They then call its Load() method to do
all of the typechecking and transitive-closure computation.
ssa.NewProgram and ssa.CreatePackages have been fused into
ssa.Create, which now cannot fail, since (*Config).Load()
reports all type errors.
Also:
- The addition of an ssa.GlobalDebug builder mode flag
eliminates a loop-over-packages repeated in many clients.
- PackageInfo.Err flag unexported. Clients never see bad infos now.
- cmd/ssadump: now only looks for func "main" in package "main".
- importsOf deleted, was dead code.
STILL TODO:
- ParseFile seems like API creep (though it's convenient)
and CreateFromFiles is dangerous (w.r.t. FileSet identity).
Need to think more...
- the need for clients to rely on elementwise correspondence
of Config.CreatePkgs and Program.Created is a little sad.
- The command-line interface has not changed.
That will happen in a follow-up.
r recommends using a repeated flag: -package p -package q ...
R=gri
CC=axwalk, frederik.zipp, golang-codereviews
https://golang.org/cl/49530047
Packages were not being created for all types.Packages,
specifically, indirectly imported packages were missing.
(*Program).CreatePackages now iterates over the type-checker's
package map too.
Also: removed all concurrency from importer. I think it was
incorrect (and hard to fix).
Also: change LoadInitialPackages so that all named packages
are loaded from source. This happens regardless of whether
GCImporter is used to satisfy imports.
Details:
- importer.Config.SourceImports flag determines whether to
load all packages from *.go source.
(Before, this was indicated by Config.Build != nil.)
- importer.Config.Build field effectively defaults to
&go/build.Default. A zero importer.Config is now usable.
- importer.Importer.Config field is now exported.
- LoadPackage renamed to ImportPackage since the resulting
packages may come from GCImporter (and be incomplete).
- doImport and ImportPackage fused.
Fixesgolang/go#7028
R=gri, axwalk
CC=golang-codereviews
https://golang.org/cl/48770043
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
This improves both performance (most calls are static) and
precision (e.g. for static calls in dead code).
Also, break callees() function into smaller ones.
R=crawshaw
CC=golang-dev
https://golang.org/cl/38740045
(Elminate premature abstraction.)
The test probes used Pointer!=nil for the "is pointerlike"
predicate. Now that Pointer is a struct, they check the type
of the expression, which is more accurate. Two probes on
non-pointerlike values have beem removed.
R=crawshaw
CC=golang-dev
https://golang.org/cl/38420043
This removes about 5% of φ-nodes in one large program
and eliminates many zero-value constants.
(This does cause some Idents to no longer map to an ssa.Value.
This is observable in the oracle, whose tests are here updated.)
R=gri, gri
CC=golang-dev
https://golang.org/cl/26980043
Users should be familiar with the sizes of all other types.
Currently we assume amd64 (as do other parts of the oracle,
e.g. go/build tags). Will parameterize later.
R=crawshaw
CC=golang-dev, gri
https://golang.org/cl/29710043
- fixed a couple of TODOs
- various cleanups along the way
- adjusted clients
Once submitted, clients of go/types that don't explicitly
specify Config.Import will need to add the extra import:
import _ "code.google.com/p/go.tools/go/gcimporter"
to install the default (gc) importer in go/types.
R=adonovan, gri
CC=golang-dev
https://golang.org/cl/26390043
A DebugRef associates a source expression E with an ssa.Value
V, but until now did not record whether V was the value or the
address of E. So, we would guess from the "pointerness" of
the Value, leading to confusion in some cases, e.g.
type N *N
var n N
n = &n // lvalue and rvalue are both pointers
Now we explicitly record 'IsAddress bool' in DebugRef, and
plumb this everywhere: through (*Function).ValueForExpr and
(*Program).VarValue, all the way to forming the pointer
analysis query.
Also:
- VarValue now treats each reference to a global distinctly,
just like it does for other vars. So:
var g int
func f() {
g = 1 // VarValue(g) == Const(1:int), !isAddress
print(g) // VarValue(g) == Global(g), isAddress
}
- DebugRefs are not emitted for references to predeclared
identifiers (nil, built-in).
- DebugRefs no longer prevent lifting of an Alloc var into a
register; now we update or discard the debug info.
- TestValueForExpr: improve coverage of ssa.EnclosingFunction
by putting expectations in methods and init funcs, not just
normal funcs.
- oracle: fix golden file broken by recent
(*types.Var).IsField change.
R=gri
CC=golang-dev
https://golang.org/cl/16610045
This allows us to run/analyze multiple tests.
Also it causes the production code packages to be properly initialized.
Also:
- cmd/ssadump: improved usage message (add example;
incorporate LoadInitialPackages usage; explain how -run
finds main).
- pointer, oracle, ssa/interp: use CreateTestMainPackage.
- ssa/builder.go: remove 'rundefers' instruction from package init,
which no longer uses 'defer'.
R=gri
CC=golang-dev
https://golang.org/cl/15920047
Motivation:
Previously, we assumed that the set of types for which a
complete method set (containing all synthesized wrapper
functions) is required at runtime was the set of types
used as operands to some *ssa.MakeInterface instruction.
In fact, this is an underapproximation because types can
be derived from other ones via reflection, and some of
these may need methods. The reflect.Type API allows *T to
be derived from T, and these may have different method
sets. Reflection also allows almost any subcomponent of a
type to be accessed (with one exception: given T, defined
'type T struct{S}', you can reach S but not struct{S}).
As a result, the pointer analysis was unable to generate
all necessary constraints before running the solver,
causing a crash when reflection derives types whose
methods are unavailable. (A similar problem would afflict
an ahead-of-time compiler based on ssa. The ssa/interp
interpreter was immune only because it does not require
all wrapper methods to be created before execution
begins.)
Description:
This change causes the SSA builder to record, for each
package, the set of all types with non-empty method sets that
are referenced within that package. This set is accessed via
Packages.TypesWithMethodSets(). Program.TypesWithMethodSets()
returns its union across all packages.
The set of references that matter are:
- types of operands to some MakeInterface instruction (as before)
- types of all exported package members
- all subcomponents of the above, recursively.
This is a conservative approximation to the set of types
whose methods may be called dynamically.
We define the owning package of a type as follows:
- the owner of a named type is the package in which it is defined;
- the owner of a pointer-to-named type is the owner of that named type;
- the owner of all other types is nil.
A package must include the method sets for all types that it
owns, and all subcomponents of that type that are not owned by
another package, recursively. Types with an owner appear in
exactly one package; types with no owner (such as struct{T})
may appear within multiple packages.
(A typical Go compiler would emit multiple copies of these
methods as weak symbols; a typical linker would eliminate
duplicates.)
Also:
- go/types/typemap: implement hash function for *Tuple.
- pointer: generate nodes/constraints for all of
ssa.Program.TypesWithMethodSets().
Add rtti.go regression test.
- Add API test of Package.TypesWithMethodSets().
- Set Function.Pkg to nil (again) for wrapper functions,
since these may be shared by many packages.
- Remove a redundant logging statement.
- Document that ssa CREATE phase is in fact sequential.
Fixesgolang/go#6605
R=gri
CC=golang-dev
https://golang.org/cl/14920056
Before, we would concatenate all the init() blocks together,
resulting in incorrect treatment of a recovered panic in one
init block: the implicit return would cause the subsequent ones
to be skipped.
The result is simpler, and closer to what gc does.
The additional functions are visible in the call graph,
so some tests required updating.
R=gri
CC=crawshaw, golang-dev
https://golang.org/cl/14671044
