exp/ssa: omit Function's package name when printing intra-package references.

R=iant
CC=golang-dev
https://golang.org/cl/7307105

src/pkg/exp/ssa/func.go

@@ -344,6 +344,11 @@ func (f *Function) emit(instr Instruction) Value {
 //      "func@5.32"                 // an anonymous function
 //
 func (f *Function) FullName() string {
+	return f.fullName(nil)
+}
+
+// Like FullName, but if from==f.Pkg, suppress package qualification.
+func (f *Function) fullName(from *Package) string {
 	// Anonymous?
 	if f.Enclosing != nil {
 		return f.Name_
@@ -353,11 +358,20 @@ func (f *Function) FullName() string {
 
 	// Synthetic?
 	if f.Pkg == nil {
+		var recvType types.Type
 		if recv != nil {
-			// TODO(adonovan): print type package-qualified, if NamedType.
-			return fmt.Sprintf("(%s).%s", recv.Type, f.Name_) // bridge method
+			recvType = recv.Type // bridge method
+		} else {
+			recvType = f.Params[0].Type() // interface method thunk
 		}
-		return fmt.Sprintf("(%s).%s", f.Params[0].Type(), f.Name_) // interface method thunk
+		// TODO(adonovan): print type package-qualified, if NamedType.
+		return fmt.Sprintf("(%s).%s", recvType, f.Name_)
+	}
+
+	// "pkg." prefix for cross-package references only.
+	var pkgQual string
+	if from != f.Pkg {
+		pkgQual = f.Pkg.ImportPath + "."
 	}
 
 	// Declared method?
@@ -366,11 +380,11 @@ func (f *Function) FullName() string {
 		if isPointer(recv.Type) {
 			star = "*"
 		}
-		return fmt.Sprintf("(%s%s.%s).%s", star, f.Pkg.ImportPath, deref(recv.Type), f.Name_)
+		return fmt.Sprintf("(%s%s%s).%s", star, pkgQual, deref(recv.Type), f.Name_)
 	}
 
 	// Package-level function.
-	return fmt.Sprintf("%s.%s", f.Pkg.ImportPath, f.Name_)
+	return pkgQual + f.Name_
 }
 
 // DumpTo prints to w a human readable "disassembly" of the SSA code of

src/pkg/exp/ssa/print.go

@@ -20,9 +20,9 @@ func (id Id) String() string {
 }
 
 // relName returns the name of v relative to i.
-// In most cases, this is identical to v.Name(), but for cross-package
-// references to Functions (including methods) and Globals, the
-// package-qualified FullName is used instead.
+// In most cases, this is identical to v.Name(), but for references to
+// Functions (including methods) and Globals, the FullName is used
+// instead, explicitly package-qualified for cross-package references.
 //
 func relName(v Value, i Instruction) string {
 	switch v := v.(type) {
@@ -32,10 +32,7 @@ func relName(v Value, i Instruction) string {
 		}
 		return v.FullName()
 	case *Function:
-		if v.Pkg == nil || v.Pkg == i.Block().Func.Pkg {
-			return v.Name()
-		}
-		return v.FullName()
+		return v.fullName(i.Block().Func.Pkg)
 	}
 	return v.Name()
 }

src/pkg/exp/ssa/ssa.go

@@ -204,7 +204,7 @@ type Function struct {
 
 	Pos       token.Pos // location of the definition
 	Enclosing *Function // enclosing function if anon; nil if global
-	Pkg       *Package  // enclosing package; nil for some synthetic methods
+	Pkg       *Package  // enclosing package for Go source functions; otherwise nil
 	Prog      *Program  // enclosing program
 	Params    []*Parameter
 	FreeVars  []*Capture // free variables whose values must be supplied by closure