go.tools/go/loader: use new types.TypeAndValue mode predicates.

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

go/loader/pkginfo.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"go/ast"
 
-	"code.google.com/p/go.tools/go/exact"
 	"code.google.com/p/go.tools/go/types"
 )
 
@@ -32,90 +31,29 @@ func (info *PackageInfo) String() string {
 	return fmt.Sprintf("PackageInfo(%s)", info.Pkg.Path())
 }
 
-// TypeOf returns the type of expression e.
+// TODO(gri): move the methods below to types.Info.
-// Precondition: e belongs to the package's ASTs.
+
-//
+// TypeOf returns the type of expression e, or nil if not found.
 func (info *PackageInfo) TypeOf(e ast.Expr) types.Type {
 	if t, ok := info.Types[e]; ok {
 		return t.Type
 	}
-	// Defining ast.Idents (id := expr) get only Ident callbacks
+	// Idents appear only in Defs/Uses, not Types.
-	// but not Expr callbacks.
 	if id, ok := e.(*ast.Ident); ok {
 		return info.ObjectOf(id).Type()
 	}
-	panic("no type for expression")
+	return nil
 }
 
-// ValueOf returns the value of expression e if it is a constant, nil
+// ObjectOf returns the type-checker object denoted by the specified
-// otherwise.
+// id, or nil if not found.
-// Precondition: e belongs to the package's ASTs.
 //
-func (info *PackageInfo) ValueOf(e ast.Expr) exact.Value {
+// If id is an anonymous struct field, ObjectOf returns the field
-	return info.Types[e].Value
+// (*types.Var) it uses, not the type (*types.TypeName) it defines.
-}
-
-// ObjectOf returns the typechecker object denoted by the specified id.
-//
-// If id is an anonymous struct field, the field (*types.Var) is
-// returned, not the type (*types.TypeName).
-//
-// Precondition: id belongs to the package's ASTs.
 //
 func (info *PackageInfo) ObjectOf(id *ast.Ident) types.Object {
-	obj, ok := info.Defs[id]
+	if obj, ok := info.Defs[id]; ok {
-	if ok {
 		return obj
 	}
 	return info.Uses[id]
 }
-
-// IsType returns true iff expression e denotes a type.
-// Precondition: e belongs to the package's ASTs.
-//
-// TODO(gri): move this into go/types.
-//
-func (info *PackageInfo) IsType(e ast.Expr) bool {
-	switch e := e.(type) {
-	case *ast.SelectorExpr: // pkg.Type
-		if _, ok := info.Selections[e]; !ok {
-			// qualified identifier
-			_, isType := info.Uses[e.Sel].(*types.TypeName)
-			return isType
-		}
-	case *ast.StarExpr: // *T
-		return info.IsType(e.X)
-	case *ast.Ident:
-		_, isType := info.ObjectOf(e).(*types.TypeName)
-		return isType
-	case *ast.ArrayType, *ast.StructType, *ast.FuncType, *ast.InterfaceType, *ast.MapType, *ast.ChanType:
-		return true
-	case *ast.ParenExpr:
-		return info.IsType(e.X)
-	}
-	return false
-}
-
-// TypeCaseVar returns the implicit variable created by a single-type
-// case clause in a type switch, or nil if not found.
-//
-func (info *PackageInfo) TypeCaseVar(cc *ast.CaseClause) *types.Var {
-	if v := info.Implicits[cc]; v != nil {
-		return v.(*types.Var)
-	}
-	return nil
-}
-
-// ImportSpecPkg returns the PkgName for a given ImportSpec, possibly
-// an implicit one for a dot-import or an import-without-rename.
-// It returns nil if not found.
-//
-func (info *PackageInfo) ImportSpecPkg(spec *ast.ImportSpec) *types.PkgName {
-	if spec.Name != nil {
-		return info.ObjectOf(spec.Name).(*types.PkgName)
-	}
-	if p := info.Implicits[spec]; p != nil {
-		return p.(*types.PkgName)
-	}
-	return nil
-}

go/ssa/builder.go

@@ -446,19 +446,23 @@ func (b *builder) exprInPlace(fn *Function, loc lvalue, e ast.Expr, isZero bool)
 // to fn and returning the Value defined by the expression.
 //
 func (b *builder) expr(fn *Function, e ast.Expr) Value {
-	// Is expression a constant?
-	if v := fn.Pkg.info.ValueOf(e); v != nil {
-		return NewConst(v, fn.Pkg.typeOf(e))
-	}
 	e = unparen(e)
-	v := b.expr0(fn, e)
+
+	tv := fn.Pkg.info.Types[e]
+
+	// Is expression a constant?
+	if tv.Value != nil {
+		return NewConst(tv.Value, tv.Type)
+	}
+
+	v := b.expr0(fn, e, tv)
 	if fn.debugInfo() {
 		emitDebugRef(fn, e, v, false)
 	}
 	return v
 }
 
-func (b *builder) expr0(fn *Function, e ast.Expr) Value {
+func (b *builder) expr0(fn *Function, e ast.Expr, tv types.TypeAndValue) Value {
 	switch e := e.(type) {
 	case *ast.BasicLit:
 		panic("non-constant BasicLit") // unreachable
@@ -479,7 +483,7 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 			return fn2
 		}
 		v := &MakeClosure{Fn: fn2}
-		v.setType(fn.Pkg.typeOf(e))
+		v.setType(tv.Type)
 		for _, fv := range fn2.FreeVars {
 			v.Bindings = append(v.Bindings, fv.outer)
 			fv.outer = nil
@@ -487,14 +491,13 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 		return fn.emit(v)
 
 	case *ast.TypeAssertExpr: // single-result form only
-		return emitTypeAssert(fn, b.expr(fn, e.X), fn.Pkg.typeOf(e), e.Lparen)
+		return emitTypeAssert(fn, b.expr(fn, e.X), tv.Type, e.Lparen)
 
 	case *ast.CallExpr:
-		typ := fn.Pkg.typeOf(e)
+		if fn.Pkg.info.Types[e.Fun].IsType() {
-		if fn.Pkg.info.IsType(e.Fun) {
 			// Explicit type conversion, e.g. string(x) or big.Int(x)
 			x := b.expr(fn, e.Args[0])
-			y := emitConv(fn, x, typ)
+			y := emitConv(fn, x, tv.Type)
 			if y != x {
 				switch y := y.(type) {
 				case *Convert:
@@ -509,8 +512,8 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 		}
 		// Call to "intrinsic" built-ins, e.g. new, make, panic.
 		if id, ok := unparen(e.Fun).(*ast.Ident); ok {
-			if obj, ok := fn.Pkg.objectOf(id).(*types.Builtin); ok {
+			if obj, ok := fn.Pkg.info.Uses[id].(*types.Builtin); ok {
-				if v := b.builtin(fn, obj, e.Args, typ, e.Lparen); v != nil {
+				if v := b.builtin(fn, obj, e.Args, tv.Type, e.Lparen); v != nil {
 					return v
 				}
 			}
@@ -518,7 +521,7 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 		// Regular function call.
 		var v Call
 		b.setCall(fn, e, &v.Call)
-		v.setType(typ)
+		v.setType(tv.Type)
 		return fn.emit(&v)
 
 	case *ast.UnaryExpr:
@@ -541,7 +544,7 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 				X:  b.expr(fn, e.X),
 			}
 			v.setPos(e.OpPos)
-			v.setType(fn.Pkg.typeOf(e))
+			v.setType(tv.Type)
 			return fn.emit(v)
 		default:
 			panic(e.Op)
@@ -554,12 +557,12 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 		case token.SHL, token.SHR:
 			fallthrough
 		case token.ADD, token.SUB, token.MUL, token.QUO, token.REM, token.AND, token.OR, token.XOR, token.AND_NOT:
-			return emitArith(fn, e.Op, b.expr(fn, e.X), b.expr(fn, e.Y), fn.Pkg.typeOf(e), e.OpPos)
+			return emitArith(fn, e.Op, b.expr(fn, e.X), b.expr(fn, e.Y), tv.Type, e.OpPos)
 
 		case token.EQL, token.NEQ, token.GTR, token.LSS, token.LEQ, token.GEQ:
 			cmp := emitCompare(fn, e.Op, b.expr(fn, e.X), b.expr(fn, e.Y), e.OpPos)
 			// The type of x==y may be UntypedBool.
-			return emitConv(fn, cmp, DefaultType(fn.Pkg.typeOf(e)))
+			return emitConv(fn, cmp, DefaultType(tv.Type))
 		default:
 			panic("illegal op in BinaryExpr: " + e.Op.String())
 		}
@@ -592,17 +595,17 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 			Max:  max,
 		}
 		v.setPos(e.Lbrack)
-		v.setType(fn.Pkg.typeOf(e))
+		v.setType(tv.Type)
 		return fn.emit(v)
 
 	case *ast.Ident:
-		obj := fn.Pkg.objectOf(e)
+		obj := fn.Pkg.info.Uses[e]
 		// Universal built-in or nil?
 		switch obj := obj.(type) {
 		case *types.Builtin:
-			return &Builtin{name: obj.Name(), sig: fn.Pkg.typeOf(e).(*types.Signature)}
+			return &Builtin{name: obj.Name(), sig: tv.Type.(*types.Signature)}
 		case *types.Nil:
-			return nilConst(fn.Pkg.typeOf(e))
+			return nilConst(tv.Type)
 		}
 		// Package-level func or var?
 		if v := fn.Prog.packageLevelValue(obj); v != nil {
@@ -624,7 +627,7 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 		case types.MethodExpr:
 			// (*T).f or T.f, the method f from the method-set of type T.
 			// The result is a "thunk".
-			return emitConv(fn, makeThunk(fn.Prog, sel), fn.Pkg.typeOf(e))
+			return emitConv(fn, makeThunk(fn.Prog, sel), tv.Type)
 
 		case types.MethodVal:
 			// e.f where e is an expression and f is a method.
@@ -645,7 +648,7 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 				Bindings: []Value{v},
 			}
 			c.setPos(e.Sel.Pos())
-			c.setType(fn.Pkg.typeOf(e))
+			c.setType(tv.Type)
 			return fn.emit(c)
 
 		case types.FieldVal:
@@ -952,10 +955,7 @@ func (b *builder) assignStmt(fn *Function, lhss, rhss []ast.Expr, isDef bool) {
 		var lval lvalue = blank{}
 		if !isBlankIdent(lhs) {
 			if isDef {
-				// Local may be "redeclared" in the same
+				if obj := fn.Pkg.info.Defs[lhs.(*ast.Ident)]; obj != nil {
-				// scope, so don't blindly create anew.
-				obj := fn.Pkg.objectOf(lhs.(*ast.Ident))
-				if _, ok := fn.objects[obj]; !ok {
 					fn.addNamedLocal(obj)
 				}
 			}
@@ -1310,7 +1310,7 @@ func (b *builder) typeSwitchStmt(fn *Function, s *ast.TypeSwitchStmt, label *lbl
 }
 
 func (b *builder) typeCaseBody(fn *Function, cc *ast.CaseClause, x Value, done *BasicBlock) {
-	if obj := fn.Pkg.info.TypeCaseVar(cc); obj != nil {
+	if obj := fn.Pkg.info.Implicits[cc]; obj != nil {
 		// In a switch y := x.(type), each case clause
 		// implicitly declares a distinct object y.
 		// In a single-type case, y has that type.
@@ -2115,7 +2115,7 @@ func (b *builder) buildFuncDecl(pkg *Package, decl *ast.FuncDecl) {
 		v.setType(types.NewTuple())
 		pkg.init.emit(&v)
 	} else {
-		fn = pkg.values[pkg.objectOf(id)].(*Function)
+		fn = pkg.values[pkg.info.Defs[id]].(*Function)
 	}
 	b.buildFunction(fn)
 }
@@ -2250,6 +2250,7 @@ func (p *Package) Build() {
 	}
 }
 
+// Like ObjectOf, but panics instead of returning nil.
 // Only valid during p's create and build phases.
 func (p *Package) objectOf(id *ast.Ident) types.Object {
 	if o := p.info.ObjectOf(id); o != nil {
@@ -2259,9 +2260,14 @@ func (p *Package) objectOf(id *ast.Ident) types.Object {
 		id.Name, p.Prog.Fset.Position(id.Pos())))
 }
 
+// Like TypeOf, but panics instead of returning nil.
 // Only valid during p's create and build phases.
 func (p *Package) typeOf(e ast.Expr) types.Type {
-	return p.info.TypeOf(e)
+	if T := p.info.TypeOf(e); T != nil {
+		return T
+	}
+	panic(fmt.Sprintf("no type for %T @ %s",
+		e, p.Prog.Fset.Position(e.Pos())))
 }
 
 // needMethodsOf ensures that runtime type information (including the

go/ssa/create.go

@@ -131,7 +131,7 @@ func membersFromDecl(pkg *Package, decl ast.Decl) {
 			for _, spec := range decl.Specs {
 				for _, id := range spec.(*ast.ValueSpec).Names {
 					if !isBlankIdent(id) {
-						memberFromObject(pkg, pkg.objectOf(id), nil)
+						memberFromObject(pkg, pkg.info.Defs[id], nil)
 					}
 				}
 			}
@@ -140,7 +140,7 @@ func membersFromDecl(pkg *Package, decl ast.Decl) {
 			for _, spec := range decl.Specs {
 				for _, id := range spec.(*ast.ValueSpec).Names {
 					if !isBlankIdent(id) {
-						memberFromObject(pkg, pkg.objectOf(id), spec)
+						memberFromObject(pkg, pkg.info.Defs[id], spec)
 					}
 				}
 			}
@@ -149,7 +149,7 @@ func membersFromDecl(pkg *Package, decl ast.Decl) {
 			for _, spec := range decl.Specs {
 				id := spec.(*ast.TypeSpec).Name
 				if !isBlankIdent(id) {
-					memberFromObject(pkg, pkg.objectOf(id), nil)
+					memberFromObject(pkg, pkg.info.Defs[id], nil)
 				}
 			}
 		}
@@ -160,7 +160,7 @@ func membersFromDecl(pkg *Package, decl ast.Decl) {
 			return // no object
 		}
 		if !isBlankIdent(id) {
-			memberFromObject(pkg, pkg.objectOf(id), decl)
+			memberFromObject(pkg, pkg.info.Defs[id], decl)
 		}
 	}
 }

go/ssa/func.go

@@ -224,7 +224,7 @@ func (f *Function) createSyntacticParams(recv *ast.FieldList, functype *ast.Func
 	if recv != nil {
 		for _, field := range recv.List {
 			for _, n := range field.Names {
-				f.addSpilledParam(f.Pkg.objectOf(n))
+				f.addSpilledParam(f.Pkg.info.Defs[n])
 			}
 			// Anonymous receiver?  No need to spill.
 			if field.Names == nil {
@@ -238,7 +238,7 @@ func (f *Function) createSyntacticParams(recv *ast.FieldList, functype *ast.Func
 		n := len(f.Params) // 1 if has recv, 0 otherwise
 		for _, field := range functype.Params.List {
 			for _, n := range field.Names {
-				f.addSpilledParam(f.Pkg.objectOf(n))
+				f.addSpilledParam(f.Pkg.info.Defs[n])
 			}
 			// Anonymous parameter?  No need to spill.
 			if field.Names == nil {
@@ -307,7 +307,7 @@ func (f *Function) finishBody() {
 		f.syntax = extentNode{n.Pos(), n.End()}
 	}
 
-	// Remove any f.Locals that are now heap-allocated.
+	// Remove from f.Locals any Allocs that escape to the heap.
 	j := 0
 	for _, l := range f.Locals {
 		if !l.Heap {
@@ -393,7 +393,7 @@ func (f *Function) addNamedLocal(obj types.Object) *Alloc {
 }
 
 func (f *Function) addLocalForIdent(id *ast.Ident) *Alloc {
-	return f.addNamedLocal(f.Pkg.objectOf(id))
+	return f.addNamedLocal(f.Pkg.info.Defs[id])
 }
 
 // addLocal creates an anonymous local variable of type typ, adds it

go/ssa/ssa.go

@@ -305,7 +305,7 @@ type Function struct {
 	Prog      *Program      // enclosing program
 	Params    []*Parameter  // function parameters; for methods, includes receiver
 	FreeVars  []*FreeVar    // free variables whose values must be supplied by closure
-	Locals    []*Alloc
+	Locals    []*Alloc      // local variables of this function
 	Blocks    []*BasicBlock // basic blocks of the function; nil => external
 	Recover   *BasicBlock   // optional; control transfers here after recovered panic
 	AnonFuncs []*Function   // anonymous functions directly beneath this one

oracle/callees.go

@@ -38,13 +38,13 @@ func callees(o *Oracle, qpos *QueryPos) (queryResult, error) {
 	// not what the user intended.
 
 	// Reject type conversions.
-	if qpos.info.IsType(e.Fun) {
+	if qpos.info.Types[e.Fun].IsType() {
 		return nil, fmt.Errorf("this is a type conversion, not a function call")
 	}
 
 	// Reject calls to built-ins.
 	if id, ok := unparen(e.Fun).(*ast.Ident); ok {
-		if b, ok := qpos.info.ObjectOf(id).(*types.Builtin); ok {
+		if b, ok := qpos.info.Uses[id].(*types.Builtin); ok {
 			return nil, fmt.Errorf("this is a call to the built-in '%s' operator", b.Name())
 		}
 	}

oracle/describe.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"go/ast"
 	"go/token"
+	"log"
 	"os"
 	"strings"
 
@@ -180,7 +181,8 @@ func findInterestingNode(pkginfo *loader.PackageInfo, path []ast.Node) ([]ast.No
 			return path, actionExpr
 
 		case *ast.SelectorExpr:
-			if pkginfo.ObjectOf(n.Sel) == nil {
+			// TODO(adonovan): use Selections info directly.
+			if pkginfo.Uses[n.Sel] == nil {
 				// TODO(adonovan): is this reachable?
 				return path, actionUnknown
 			}
@@ -267,15 +269,15 @@ func findInterestingNode(pkginfo *loader.PackageInfo, path []ast.Node) ([]ast.No
 				return path[1:], actionPackage
 
 			default:
-				// e.g. blank identifier (go/types bug?)
+				// e.g. blank identifier
-				// or y in "switch y := x.(type)" (go/types bug?)
+				// or y in "switch y := x.(type)"
 				// or code in a _test.go file that's not part of the package.
-				fmt.Printf("unknown reference %s in %T\n", n, path[1])
+				log.Printf("unknown reference %s in %T\n", n, path[1])
 				return path, actionUnknown
 			}
 
 		case *ast.StarExpr:
-			if pkginfo.IsType(n) {
+			if pkginfo.Types[n].IsType() {
 				return path, actionType
 			}
 			return path, actionExpr
@@ -311,7 +313,7 @@ func describeValue(o *Oracle, qpos *QueryPos, path []ast.Node) (*describeValueRe
 	}
 
 	typ := qpos.info.TypeOf(expr)
-	constVal := qpos.info.ValueOf(expr)
+	constVal := qpos.info.Types[expr].Value
 
 	return &describeValueResult{
 		qpos:     qpos,
@@ -497,7 +499,12 @@ func describePackage(o *Oracle, qpos *QueryPos, path []ast.Node) (*describePacka
 	var pkg *types.Package
 	switch n := path[0].(type) {
 	case *ast.ImportSpec:
-		pkgname := qpos.info.ImportSpecPkg(n)
+		var pkgname *types.PkgName
+		if n.Name != nil {
+			pkgname = qpos.info.Defs[n.Name].(*types.PkgName)
+		} else if p := qpos.info.Implicits[n]; p != nil {
+			pkgname = p.(*types.PkgName)
+		}
 		description = fmt.Sprintf("import of package %q", pkgname.Pkg().Path())
 		pkg = pkgname.Pkg()
 
@@ -507,7 +514,7 @@ func describePackage(o *Oracle, qpos *QueryPos, path []ast.Node) (*describePacka
 			pkg = qpos.info.Pkg
 			description = fmt.Sprintf("definition of package %q", pkg.Path())
 		} else {
-			// e.g. import id
+			// e.g. import id "..."
 			//  or  id.F()
 			pkg = qpos.info.ObjectOf(n).Pkg()
 			description = fmt.Sprintf("reference to package %q", pkg.Path())
@@ -662,7 +669,7 @@ func describeStmt(o *Oracle, qpos *QueryPos, path []ast.Node) (*describeStmtResu
 	var description string
 	switch n := path[0].(type) {
 	case *ast.Ident:
-		if qpos.info.ObjectOf(n).Pos() == n.Pos() {
+		if qpos.info.Defs[n] != nil {
 			description = "labelled statement"
 		} else {
 			description = "reference to labelled statement"

oracle/freevars.go

@@ -51,17 +51,13 @@ func freevars(o *Oracle, qpos *QueryPos) (queryResult, error) {
 	}
 
 	id = func(n *ast.Ident) types.Object {
-		obj := qpos.info.ObjectOf(n)
+		obj := qpos.info.Uses[n]
 		if obj == nil {
-			return nil // TODO(adonovan): fix: this fails for *types.Label.
+			return nil // not a reference
-			panic("no types.Object for ast.Ident")
 		}
 		if _, ok := obj.(*types.PkgName); ok {
 			return nil // imported package
 		}
-		if n.Pos() == obj.Pos() {
-			return nil // this ident is the definition, not a reference
-		}
 		if !(file.Pos() <= obj.Pos() && obj.Pos() <= file.End()) {
 			return nil // not defined in this file
 		}

refactor/eg/eg.go

@@ -113,7 +113,7 @@ Dot imports are forbidden in the template.
 // TODO(adonovan): expand upon the above documentation as an HTML page.
 
 // TODO(adonovan): eliminate dependency on loader.PackageInfo.
-// Move its ObjectOf/IsType/TypeOf methods into go/types.
+// Move its TypeOf method into go/types.
 
 // A Transformer represents a single example-based transformation.
 type Transformer struct {

refactor/eg/match.go

@@ -105,7 +105,7 @@ func (tr *Transformer) matchExpr(x, y ast.Expr) bool {
 	case *ast.CallExpr:
 		y := y.(*ast.CallExpr)
 		match := tr.matchExpr // function call
-		if tr.info.IsType(x.Fun) {
+		if tr.info.Types[x.Fun].IsType() {
 			match = tr.matchType // type conversion
 		}
 		return x.Ellipsis.IsValid() == y.Ellipsis.IsValid() &&