go.tools/ssa: de-dup the creation of method sets, using typemap.

Yields a ~20% improvement in SSA construction time.

Also: better names for promotion wrapper functions.

R=gri
CC=golang-dev
https://golang.org/cl/11050043

go/types/typemap/typemap_test.go

@@ -6,10 +6,11 @@ package typemap_test
 //   (e.g. all types generated by type-checking some body of real code).
 
 import (
-	"code.google.com/p/go.tools/go/types"
-	"code.google.com/p/go.tools/go/types/typemap"
 	"go/ast"
 	"testing"
+
+	"code.google.com/p/go.tools/go/types"
+	"code.google.com/p/go.tools/go/types/typemap"
 )
 
 var (

ssa/create.go

@@ -39,7 +39,6 @@ func NewProgram(fset *token.FileSet, mode BuilderMode) *Program {
 		PackagesByPath:      make(map[string]*Package),
 		packages:            make(map[*types.Package]*Package),
 		builtins:            make(map[types.Object]*Builtin),
-		methodSets:          make(map[types.Type]MethodSet),
 		concreteMethods:     make(map[*types.Func]*Function),
 		indirectionWrappers: make(map[*Function]*Function),
 		boundMethodWrappers: make(map[*Function]*Function),

ssa/promote.go

@@ -81,14 +81,13 @@ type candidate struct {
 	path     *anonFieldPath // desugared selector path
 }
 
-// For debugging.
 func (c candidate) String() string {
 	s := ""
 	// Inefficient!
 	for p := c.path; p != nil; p = p.tail {
 		s = "." + p.field.Name() + s
 	}
-	return "@" + s + "." + c.method.Name()
+	return s + "." + c.method.Name()
 }
 
 // ptrRecv returns true if this candidate has a pointer receiver.
@@ -110,15 +109,12 @@ func (p *Program) MethodSet(typ types.Type) MethodSet {
 	p.methodsMu.Lock()
 	defer p.methodsMu.Unlock()
 
-	// TODO(adonovan): Using Types as map keys doesn't properly
+	mset := p.methodSets.At(typ)
-	// de-dup.  e.g. *Named are canonical but *Struct and
-	// others are not.  Need to de-dup using typemap.T.
-	mset := p.methodSets[typ]
 	if mset == nil {
 		mset = buildMethodSet(p, typ)
-		p.methodSets[typ] = mset
+		p.methodSets.Set(typ, mset)
 	}
-	return mset
+	return mset.(MethodSet)
 }
 
 // buildMethodSet computes the concrete method set for type typ.
@@ -282,12 +278,12 @@ func promotionWrapper(prog *Program, typ types.Type, cand *candidate) *Function
 	// TODO(adonovan): consult memoization cache keyed by (typ, cand).
 	// Needs typemap.  Also needs hash/eq functions for 'candidate'.
 	if prog.mode&LogSource != 0 {
-		defer logStack("promotionWrapper %s, %s, type %s", typ, cand, sig)()
+		defer logStack("promotionWrapper (%s)%s, type %s", typ, cand, sig)()
 	}
 	fn := &Function{
 		name:      cand.method.Name(),
 		Signature: sig,
-		Synthetic: "promotion wrapper for " + cand.String(),
+		Synthetic: fmt.Sprintf("promotion wrapper for (%s)%s", typ, cand),
 		Prog:      prog,
 		pos:       cand.method.Pos(),
 	}

ssa/ssa.go

@@ -11,6 +11,7 @@ import (
 
 	"code.google.com/p/go.tools/go/exact"
 	"code.google.com/p/go.tools/go/types"
+	"code.google.com/p/go.tools/go/types/typemap"
 	"code.google.com/p/go.tools/importer"
 )
 
@@ -25,7 +26,7 @@ type Program struct {
 	mode            BuilderMode                 // set of mode bits for SSA construction
 
 	methodsMu           sync.Mutex                // guards the following maps:
-	methodSets          map[types.Type]MethodSet  // concrete method set each type [TODO(adonovan): de-dup]
+	methodSets          typemap.M                 // maps type to its concrete MethodSet
 	indirectionWrappers map[*Function]*Function   // func(*T) wrappers for T-methods
 	boundMethodWrappers map[*Function]*Function   // wrappers for curried x.Method closures
 	ifaceMethodWrappers map[*types.Func]*Function // wrappers for curried I.Method functions