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
The new method is functionally identical to typeCheck, and
obviates the LoadMainPackage method.
Updated all clients.
Fixes bug 6561.
R=gri
CC=golang-dev
https://golang.org/cl/14494051
Motivation: pointer analysis tools (like the oracle) want the
user to specify a set of initial packages, like 'go test'.
This change enables the user to specify a set of packages on
the command line using importer.LoadInitialPackages(args).
Each argument is interpreted as either:
- a comma-separated list of *.go source files together
comprising one non-importable ad-hoc package.
e.g. "src/pkg/net/http/triv.go" gives us [main].
- an import path, denoting both the imported package
and its non-importable external test package, if any.
e.g. "fmt" gives us [fmt, fmt_test].
Current type-checker limitations mean that only the first
import path may contribute tests: multiple packages augmented
by *_test.go files could create import cycles, which 'go test'
avoids by building a separate executable for each one.
That approach is less attractive for static analysis.
Details: (many files touched, but importer.go is the crux)
importer:
- PackageInfo.Importable boolean indicates whether
package is importable.
- un-expose Importer.Packages; expose AllPackages() instead.
- CreatePackageFromArgs has become LoadInitialPackages.
- imports() moved to util.go, renamed importsOf().
- InitialPackagesUsage usage message exported to clients.
- the package name for ad-hoc packages now comes from the
'package' decl, not "main".
ssa.Program:
- added CreatePackages() method
- PackagesByPath un-exposed, renamed 'imported'.
- expose AllPackages and ImportedPackage accessors.
oracle:
- describe: explain and workaround a go/types bug.
Misc:
- Removed various unnecessary error.Error() calls in Printf args.
R=crawshaw
CC=golang-dev
https://golang.org/cl/13579043
1. ParseFiles (in util.go) parses each file in its own goroutine.
2. (*Importer).LoadPackage asynchronously prefetches the
import graph by scanning the imports of each loaded package
and calling LoadPackage on each one.
LoadPackage is now thread-safe and idempotent: it uses a
condition variable per package; the first goroutine to
request a package becomes responsible for loading it and
broadcasts to the others (waiting) when it becomes ready.
ssadump runs 34% faster when loading the oracle.
Also, refactorings:
- delete SourceLoader mechanism; just expose go/build.Context directly.
- CreateSourcePackage now also returns an error directly,
rather than via PackageInfo.Err, since every client wants that.
R=crawshaw
CC=golang-dev
https://golang.org/cl/13509045
Before, VarValue looked for the ssa.Value for the 'var' object
in the same package as the object was defined, but this is
(obviously) wrong for a cross-package FieldVal selection,
expr.f. The caller must provide the package containing the
reference.
+ test.
Also:
- add 2 TODOs.
- split builder.expr into two functions so we don't need
defer, which makes panic dumps harder to read.
R=golang-dev, crawshaw
CC=golang-dev
https://golang.org/cl/13257045
CanonicalPos was inadequate since many pairs of instruction share the same pos (e.g. Allocs and Phis). Instead, we generalize the DebugRef instruction to associate not just Idents but Exprs with ssa.Values.
We no longer store any DebugRefs for constant expressions, to save space. (The type and value of such expressions can be obtained by other means, at a cost in complexity.)
Function.ValueForExpr queries the DebugRef info to return the ssa.Value of a given Expr.
Added tests.
Also:
- the DebugInfo flag is now per package, not global.
It must be set between Create and Build phases if desired.
- {Value,Instruction}.Pos() documentation updated: we still maintain
this information in the instruction stream even in non-debug mode,
but we make fewer claims about its invariants.
- Go and Defer instructions can now use their respective go/defer
token positions (not the call's lparen), so they do.
- SelectState:
Posn token.Pos indicates the <- position
DebugNode ast.Expr is the send stmt or receive expr.
- In building SelectStmt, we introduce extra temporaries in debug
mode to hold the result of the receive in 'case <-ch' even though
this value isn't ordinarily needed.
- Use *SelectState (indirectly) since the struct is getting bigger.
- Document some missing instructions in doc.go.
R=gri
CC=golang-dev
https://golang.org/cl/12147043
Also:
- Implement Program.FuncValue for interface methods (+ test).
- go/types.Object.String(): don't package-qualify names unless
they are package level objects---otherwise you see "main.x" for
locals, struct fields, etc.
- go/types.Func.String(): don't assume Type() is *Signature;
it could be *Builtin.
R=gri
CC=golang-dev
https://golang.org/cl/12058045
ssa:
- Prog.CreatePackages inlined into all callers.
- Prog.CreatePackage is now exposed; idempotent; and checks for errors.
- '*address' not 'address' now implements lvalue (since it's 6 words).
- removed types.Method case from createMemberFromObject.
importer:
- added importer.PackageInfo.String method.
- simplifed importer.PackageInfo by putting types.Info in it.
- removed obsolete precondition from IsType.
R=gri
CC=golang-dev
https://golang.org/cl/11408045
(Motivation: "Literal" is a syntactic property, not a semantic one.)
Also: delete a "TODO: opt" that the lifting pass already does for us.
R=gri
CC=golang-dev
https://golang.org/cl/11351043
This CL adds three new functions to determine the SSA Value
for a given syntactic var, func or const object:
Program.{Const,Func,Var}Value.
Since constants and functions are immutable, the first
two only need a types.Object; but each distinct
reference to a var may return a distinct Value, so the third
requires an ast.Ident parameter too.
Debug information for local vars is encoded in the
instruction stream in the form of DebugRef instructions,
which are a no-op but relate their operand to a particular
ident in the AST. The beauty of this approach is that it
naturally stays consistent during optimisation passes
(e.g. lifting) without additional bookkeeping.
DebugRef instructions are only generated if the DebugMode
builder flag is set; I plan to make the policy more fine-
grained (per function).
DebugRef instructions are inserted for:
- expr(Ident) for rvalue idents
- address.store() for idents that update an lvalue
- address.address() for idents that take address of lvalue
(this new method replaces all uses of lval.(address).addr)
- expr() for all constant expressions
- local ValueSpecs with implicit zero initialization (no RHS)
(this case doesn't call store() or address())
To ensure we don't forget to emit debug info for uses of Idents,
we must use the lvalue mechanism consistently. (Previously,
many simple cases had effectively inlined these functions.)
Similarly setCallFunc no longer inlines expr(Ident).
Also:
- Program.Value() has been inlined & specialized.
- Program.Package() has moved nearer the new lookup functions.
- refactoring: funcSyntax has lost paramFields, resultFields;
gained funcType, which provides access to both.
- add package-level constants to Package.values map.
- opt: don't call localValueSpec for constants.
(The resulting code is always optimised away.)
There are a number of comments asking whether Literals
should have positions. Will address in a follow-up.
Added tests of all interesting cases.
R=gri
CC=golang-dev
https://golang.org/cl/11259044
Details:
- builder is now un-exported and is now a per-package entity.
- Package.nTo1Vars is now part of builder, where it belongs.
- CREATE phase code split out into its own file, create.go
- Context type is gone; it had become trivial after the
Importer refactoring.
- importer.PackageInfo.Imports() now encapsulates iteration
over imports.
Typical usage is now:
prog := ssa.NewProgram(imp.Fset, mode)
prog.CreatePackages(imp)
prog.BuildAll()
Builder.BuildPackage(Package) is now Package.Build()
Builder.BuildAllPackages() is now Program.BuildAll()
R=iant, gri
CC=golang-dev
https://golang.org/cl/9970044
A Builder is now just a Program and a Context.
Details of this CL:
- Builder.imp field removed.
- Builder.globals split up into Package.values and Prog.Builtins.
- Builder.packages moved to Prog.packages.
- Builder.PackageFor moved to Program.Package(types.Object)
- Program.Lookup() func replaces Builder.globals map.
- also: keep Package.info field around until end of BuildPackage.
Planned follow-ups to eliminate Builder from API:
- split NewBuilder up into NewProgram and Program.CreatePackages(...)
- move Builder.BuildAllPackages -> Program.BuildAll(Context)
- move Builder.BuildPackage -> Package.Build(Context)
R=gri, iant
CC=golang-dev
https://golang.org/cl/9966044
PLEASE NOTE: the APIs for both "importer" and "ssa" packages
will continue to evolve and both need some polishing; the key
thing is that this CL splits them.
The go.types/importer package contains contains the Importer,
which takes care of the mechanics of loading a set of packages
and type-checking them. It exposes for each package a
PackageInfo containing:
- the package's ASTs (i.e. the input to the typechecker)
- the types.Package object
- the memoization of the typechecker callbacks for identifier
resolution, constant folding and expression type inference.
Method-set computation (and hence bridge-method creation) is
now moved to after creation of all packages: since they are no
longer created in topological order, we can't guarantee the
needed delegate methods exist yet.
ssa.Package no longer has public TypeOf, ObjectOf, ValueOf methods.
The private counterparts are valid only during the build phase.
Also:
- added to go/types an informative error (not crash) for an
importer() returning nil without error.
- removed Package.Name(), barely needed.
- changed Package.String() slightly.
- flag what looks like a bug in makeBridgeMethod. Will follow up.
R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/9898043
PathEnclosingInterval: maps a source position to an ast.Node.
EnclosingFunction: finds ssa.Function enclosing an ast.Node.
HasEnclosingFunction: cheaper impl of EnclosingFunction()!=nil
NodeDescription: user friendly node type descriptions.
+ tests.
Also: make ssa.Package.TypeInfo field a pointer.
R=gri, r
CC=golang-dev
https://golang.org/cl/9639045
