diff --git a/call/util.go b/call/util.go
index d4f39236..855e3701 100644
--- a/call/util.go
+++ b/call/util.go
@@ -20,7 +20,7 @@ package call
 // Add a utility function to eliminate all context from a call graph.
 
 // CalleesOf returns a new set containing all direct callees of the
-// caller node in call graph g.
+// caller node.
 //
 func CalleesOf(caller GraphNode) map[GraphNode]bool {
 	callees := make(map[GraphNode]bool)
@@ -31,23 +31,33 @@ func CalleesOf(caller GraphNode) map[GraphNode]bool {
 }
 
 // GraphVisitEdges visits all the edges in graph g in depth-first order.
-// The edge function is called for each edge in postorder.
+// The edge function is called for each edge in postorder.  If it
+// returns non-nil, visitation stops and GraphVisitEdges returns that
+// value.
 //
-func GraphVisitEdges(g Graph, edge func(Edge)) {
+func GraphVisitEdges(g Graph, edge func(Edge) error) error {
 	seen := make(map[GraphNode]bool)
-	var visit func(n GraphNode)
-	visit = func(n GraphNode) {
+	var visit func(n GraphNode) error
+	visit = func(n GraphNode) error {
 		if !seen[n] {
 			seen[n] = true
 			for _, e := range n.Edges() {
-				visit(e.Callee)
-				edge(e)
+				if err := visit(e.Callee); err != nil {
+					return err
+				}
+				if err := edge(e); err != nil {
+					return err
+				}
 			}
 		}
+		return nil
 	}
 	for _, n := range g.Nodes() {
-		visit(n)
+		if err := visit(n); err != nil {
+			return err
+		}
 	}
+	return nil
 }
 
 // PathSearch finds an arbitrary path starting at node start and
diff --git a/oracle/callees.go b/oracle/callees.go
index 3362bb5a..3d6a3b6b 100644
--- a/oracle/callees.go
+++ b/oracle/callees.go
@@ -12,7 +12,6 @@ import (
 
 	"code.google.com/p/go.tools/go/types"
 	"code.google.com/p/go.tools/oracle/serial"
-	"code.google.com/p/go.tools/pointer"
 	"code.google.com/p/go.tools/ssa"
 )
 
@@ -22,14 +21,19 @@ import (
 // TODO(adonovan): if a callee is a wrapper, show the callee's callee.
 //
 func callees(o *Oracle, qpos *QueryPos) (queryResult, error) {
+	pkg := o.prog.Package(qpos.info.Pkg)
+	if pkg == nil {
+		return nil, fmt.Errorf("no SSA package")
+	}
+
 	// Determine the enclosing call for the specified position.
-	var call *ast.CallExpr
+	var e *ast.CallExpr
 	for _, n := range qpos.path {
-		if call, _ = n.(*ast.CallExpr); call != nil {
+		if e, _ = n.(*ast.CallExpr); e != nil {
 			break
 		}
 	}
-	if call == nil {
+	if e == nil {
 		return nil, fmt.Errorf("there is no function call here")
 	}
 	// TODO(adonovan): issue an error if the call is "too far
@@ -37,12 +41,12 @@ func callees(o *Oracle, qpos *QueryPos) (queryResult, error) {
 	// not what the user intended.
 
 	// Reject type conversions.
-	if qpos.info.IsType(call.Fun) {
+	if qpos.info.IsType(e.Fun) {
 		return nil, fmt.Errorf("this is a type conversion, not a function call")
 	}
 
 	// Reject calls to built-ins.
-	if id, ok := unparen(call.Fun).(*ast.Ident); ok {
+	if id, ok := unparen(e.Fun).(*ast.Ident); ok {
 		if b, ok := qpos.info.ObjectOf(id).(*types.Builtin); ok {
 			return nil, fmt.Errorf("this is a call to the built-in '%s' operator", b.Name())
 		}
@@ -50,64 +54,68 @@ func callees(o *Oracle, qpos *QueryPos) (queryResult, error) {
 
 	buildSSA(o)
 
-	// Compute the subgraph of the callgraph for callsite(s)
-	// arising from 'call'.  There may be more than one if its
-	// enclosing function was treated context-sensitively.
-	// (Or zero if it was in dead code.)
-	//
-	// The presence of a key indicates this call site is
-	// interesting even if the value is nil.
-	querySites := make(map[pointer.CallSite][]pointer.CallGraphNode)
-	var arbitrarySite pointer.CallSite
-	o.config.CallSite = func(site pointer.CallSite) {
-		if site.Pos() == call.Lparen {
-			// Not a no-op!  Ensures key is
-			// present even if value is nil:
-			querySites[site] = querySites[site]
-			arbitrarySite = site
-		}
-	}
-	o.config.Call = func(site pointer.CallSite, callee pointer.CallGraphNode) {
-		if targets, ok := querySites[site]; ok {
-			querySites[site] = append(targets, callee)
-		}
-	}
-	ptrAnalysis(o)
-
-	if arbitrarySite == nil {
-		return nil, fmt.Errorf("this call site is unreachable in this analysis")
+	// Ascertain calling function and call site.
+	callerFn := ssa.EnclosingFunction(pkg, qpos.path)
+	if callerFn == nil {
+		return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
 	}
 
-	// Compute union of callees across all contexts.
-	funcsMap := make(map[*ssa.Function]bool)
-	for _, callees := range querySites {
-		for _, callee := range callees {
-			funcsMap[callee.Func()] = true
+	o.config.BuildCallGraph = true
+	callgraph := ptrAnalysis(o).CallGraph
+
+	// Find the call site and all edges from it.
+	var site ssa.CallInstruction
+	calleesMap := make(map[*ssa.Function]bool)
+	for _, n := range callgraph.Nodes() {
+		if n.Func() == callerFn {
+			if site == nil {
+				// First node for callerFn: identify the site.
+				for _, s := range n.Sites() {
+					if s.Pos() == e.Lparen {
+						site = s
+						break
+					}
+				}
+				if site == nil {
+					return nil, fmt.Errorf("this call site is unreachable in this analysis")
+				}
+			}
+
+			for _, edge := range n.Edges() {
+				if edge.Site == site {
+					calleesMap[edge.Callee.Func()] = true
+				}
+			}
 		}
 	}
-	funcs := make([]*ssa.Function, 0, len(funcsMap))
-	for f := range funcsMap {
+	if site == nil {
+		return nil, fmt.Errorf("this function is unreachable in this analysis")
+	}
+
+	// Discard context, de-duplicate and sort.
+	funcs := make([]*ssa.Function, 0, len(calleesMap))
+	for f := range calleesMap {
 		funcs = append(funcs, f)
 	}
 	sort.Sort(byFuncPos(funcs))
 
 	return &calleesResult{
-		site:  arbitrarySite,
+		site:  site,
 		funcs: funcs,
 	}, nil
 }
 
 type calleesResult struct {
-	site  pointer.CallSite
+	site  ssa.CallInstruction
 	funcs []*ssa.Function
 }
 
 func (r *calleesResult) display(printf printfFunc) {
 	if len(r.funcs) == 0 {
 		// dynamic call on a provably nil func/interface
-		printf(r.site, "%s on nil value", r.site.Description())
+		printf(r.site, "%s on nil value", r.site.Common().Description())
 	} else {
-		printf(r.site, "this %s dispatches to:", r.site.Description())
+		printf(r.site, "this %s dispatches to:", r.site.Common().Description())
 		for _, callee := range r.funcs {
 			printf(callee, "\t%s", callee)
 		}
@@ -117,7 +125,7 @@ func (r *calleesResult) display(printf printfFunc) {
 func (r *calleesResult) toSerial(res *serial.Result, fset *token.FileSet) {
 	j := &serial.Callees{
 		Pos:  fset.Position(r.site.Pos()).String(),
-		Desc: r.site.Description(),
+		Desc: r.site.Common().Description(),
 	}
 	for _, callee := range r.funcs {
 		j.Callees = append(j.Callees, &serial.CalleesItem{
diff --git a/oracle/callers.go b/oracle/callers.go
index bba19d21..e773a2d6 100644
--- a/oracle/callers.go
+++ b/oracle/callers.go
@@ -8,8 +8,8 @@ import (
 	"fmt"
 	"go/token"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/oracle/serial"
-	"code.google.com/p/go.tools/pointer"
 	"code.google.com/p/go.tools/ssa"
 )
 
@@ -36,54 +36,57 @@ func callers(o *Oracle, qpos *QueryPos) (queryResult, error) {
 
 	// Run the pointer analysis, recording each
 	// call found to originate from target.
-	var calls []pointer.CallSite
-	o.config.Call = func(site pointer.CallSite, callee pointer.CallGraphNode) {
-		if callee.Func() == target {
-			calls = append(calls, site)
+	o.config.BuildCallGraph = true
+	callgraph := ptrAnalysis(o).CallGraph
+	var edges []call.Edge
+	call.GraphVisitEdges(callgraph, func(edge call.Edge) error {
+		if edge.Callee.Func() == target {
+			edges = append(edges, edge)
 		}
-	}
-	// TODO(adonovan): sort calls, to ensure test determinism.
-
-	root := ptrAnalysis(o)
+		return nil
+	})
+	// TODO(adonovan): sort + dedup calls to ensure test determinism.
 
 	return &callersResult{
-		target: target,
-		root:   root,
-		calls:  calls,
+		target:    target,
+		callgraph: callgraph,
+		edges:     edges,
 	}, nil
 }
 
 type callersResult struct {
-	target *ssa.Function
-	root   pointer.CallGraphNode
-	calls  []pointer.CallSite
+	target    *ssa.Function
+	callgraph call.Graph
+	edges     []call.Edge
 }
 
 func (r *callersResult) display(printf printfFunc) {
-	if r.calls == nil {
+	root := r.callgraph.Root()
+	if r.edges == nil {
 		printf(r.target, "%s is not reachable in this program.", r.target)
 	} else {
-		printf(r.target, "%s is called from these %d sites:", r.target, len(r.calls))
-		for _, site := range r.calls {
-			if site.Caller() == r.root {
+		printf(r.target, "%s is called from these %d sites:", r.target, len(r.edges))
+		for _, edge := range r.edges {
+			if edge.Caller == root {
 				printf(r.target, "the root of the call graph")
 			} else {
-				printf(site, "\t%s from %s", site.Description(), site.Caller().Func())
+				printf(edge.Site, "\t%s from %s", edge.Site.Common().Description(), edge.Caller.Func())
 			}
 		}
 	}
 }
 
 func (r *callersResult) toSerial(res *serial.Result, fset *token.FileSet) {
+	root := r.callgraph.Root()
 	var callers []serial.Caller
-	for _, site := range r.calls {
+	for _, edge := range r.edges {
 		var c serial.Caller
-		c.Caller = site.Caller().Func().String()
-		if site.Caller() == r.root {
+		c.Caller = edge.Caller.Func().String()
+		if edge.Caller == root {
 			c.Desc = "synthetic call"
 		} else {
-			c.Pos = fset.Position(site.Pos()).String()
-			c.Desc = site.Description()
+			c.Pos = fset.Position(edge.Site.Pos()).String()
+			c.Desc = edge.Site.Common().Description()
 		}
 		callers = append(callers, c)
 	}
diff --git a/oracle/callgraph.go b/oracle/callgraph.go
index 3598fd84..590fa640 100644
--- a/oracle/callgraph.go
+++ b/oracle/callgraph.go
@@ -8,8 +8,8 @@ import (
 	"go/token"
 	"strings"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/oracle/serial"
-	"code.google.com/p/go.tools/pointer"
 )
 
 // callgraph displays the entire callgraph of the current program.
@@ -23,42 +23,24 @@ import (
 // TODO(adonovan): add an option to project away context sensitivity.
 // The callgraph API should provide this feature.
 //
+// TODO(adonovan): add an option to partition edges by call site.
+//
 // TODO(adonovan): elide nodes for synthetic functions?
 //
 func callgraph(o *Oracle, _ *QueryPos) (queryResult, error) {
 	buildSSA(o)
 
 	// Run the pointer analysis and build the complete callgraph.
-	callgraph := make(pointer.CallGraph)
-	o.config.Call = callgraph.AddEdge
-	root := ptrAnalysis(o)
-
-	// Assign (preorder) numbers to all the callgraph nodes.
-	// TODO(adonovan): the callgraph API should do this for us.
-	// (Actually, it does have unique numbers under the hood.)
-	numbering := make(map[pointer.CallGraphNode]int)
-	var number func(cgn pointer.CallGraphNode)
-	number = func(cgn pointer.CallGraphNode) {
-		if _, ok := numbering[cgn]; !ok {
-			numbering[cgn] = len(numbering)
-			for callee := range callgraph[cgn] {
-				number(callee)
-			}
-		}
-	}
-	number(root)
+	o.config.BuildCallGraph = true
+	ptares := ptrAnalysis(o)
 
 	return &callgraphResult{
-		root:      root,
-		callgraph: callgraph,
-		numbering: numbering,
+		callgraph: ptares.CallGraph,
 	}, nil
 }
 
 type callgraphResult struct {
-	root      pointer.CallGraphNode
-	callgraph pointer.CallGraph
-	numbering map[pointer.CallGraphNode]int
+	callgraph call.Graph
 }
 
 func (r *callgraphResult) display(printf printfFunc) {
@@ -71,34 +53,41 @@ Some nodes may appear multiple times due to context-sensitive
  treatment of some calls.
 `)
 
-	// TODO(adonovan): compute the numbers as we print; right now
-	// it depends on map iteration so it's arbitrary,which is ugly.
-	seen := make(map[pointer.CallGraphNode]bool)
-	var print func(cgn pointer.CallGraphNode, indent int)
-	print = func(cgn pointer.CallGraphNode, indent int) {
-		n := r.numbering[cgn]
-		if !seen[cgn] {
-			seen[cgn] = true
-			printf(cgn.Func(), "%d\t%s%s", n, strings.Repeat("    ", indent), cgn.Func())
-			for callee := range r.callgraph[cgn] {
+	seen := make(map[call.GraphNode]int)
+	var print func(cgn call.GraphNode, indent int)
+	print = func(cgn call.GraphNode, indent int) {
+		fn := cgn.Func()
+		if num, ok := seen[cgn]; !ok {
+			num = len(seen)
+			seen[cgn] = num
+			printf(fn, "%d\t%s%s", num, strings.Repeat("    ", indent), fn)
+			// Don't use Edges(), which distinguishes callees by call site.
+			for callee := range call.CalleesOf(cgn) {
 				print(callee, indent+1)
 			}
 		} else {
-			printf(cgn.Func(), "\t%s%s (%d)", strings.Repeat("    ", indent), cgn.Func(), n)
+			printf(fn, "\t%s%s (%d)", strings.Repeat("    ", indent), fn, num)
 		}
 	}
-	print(r.root, 0)
+	print(r.callgraph.Root(), 0)
 }
 
 func (r *callgraphResult) toSerial(res *serial.Result, fset *token.FileSet) {
-	cg := make([]serial.CallGraph, len(r.numbering))
-	for n, i := range r.numbering {
+	nodes := r.callgraph.Nodes()
+
+	numbering := make(map[call.GraphNode]int)
+	for i, n := range nodes {
+		numbering[n] = i
+	}
+
+	cg := make([]serial.CallGraph, len(nodes))
+	for i, n := range nodes {
 		j := &cg[i]
 		fn := n.Func()
 		j.Name = fn.String()
 		j.Pos = fset.Position(fn.Pos()).String()
-		for callee := range r.callgraph[n] {
-			j.Children = append(j.Children, r.numbering[callee])
+		for callee := range call.CalleesOf(n) {
+			j.Children = append(j.Children, numbering[callee])
 		}
 	}
 	res.Callgraph = cg
diff --git a/oracle/callstack.go b/oracle/callstack.go
index 2c3aeba7..57adfff2 100644
--- a/oracle/callstack.go
+++ b/oracle/callstack.go
@@ -8,8 +8,8 @@ import (
 	"fmt"
 	"go/token"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/oracle/serial"
-	"code.google.com/p/go.tools/pointer"
 	"code.google.com/p/go.tools/ssa"
 )
 
@@ -41,57 +41,36 @@ func callstack(o *Oracle, qpos *QueryPos) (queryResult, error) {
 	}
 
 	// Run the pointer analysis and build the complete call graph.
-	callgraph := make(pointer.CallGraph)
-	o.config.Call = callgraph.AddEdge
-	root := ptrAnalysis(o)
+	o.config.BuildCallGraph = true
+	callgraph := ptrAnalysis(o).CallGraph
 
-	seen := make(map[pointer.CallGraphNode]bool)
-	var callstack []pointer.CallSite
-
-	// Use depth-first search to find an arbitrary path from a
-	// root to the target function.
-	var search func(cgn pointer.CallGraphNode) bool
-	search = func(cgn pointer.CallGraphNode) bool {
-		if !seen[cgn] {
-			seen[cgn] = true
-			if cgn.Func() == target {
-				return true
-			}
-			for callee, site := range callgraph[cgn] {
-				if search(callee) {
-					callstack = append(callstack, site)
-					return true
-				}
-			}
-		}
-		return false
-	}
-
-	for toplevel := range callgraph[root] {
-		if search(toplevel) {
-			break
-		}
+	// Search for an arbitrary path from a root to the target function.
+	isEnd := func(n call.GraphNode) bool { return n.Func() == target }
+	callpath := call.PathSearch(callgraph.Root(), isEnd)
+	if callpath != nil {
+		callpath = callpath[1:] // remove synthetic edge from <root>
 	}
 
 	return &callstackResult{
-		qpos:      qpos,
-		target:    target,
-		callstack: callstack,
+		qpos:     qpos,
+		target:   target,
+		callpath: callpath,
 	}, nil
 }
 
 type callstackResult struct {
-	qpos      *QueryPos
-	target    *ssa.Function
-	callstack []pointer.CallSite
+	qpos     *QueryPos
+	target   *ssa.Function
+	callpath []call.Edge
 }
 
 func (r *callstackResult) display(printf printfFunc) {
-	if r.callstack != nil {
+	if r.callpath != nil {
 		printf(r.qpos, "Found a call path from root to %s", r.target)
 		printf(r.target, "%s", r.target)
-		for _, site := range r.callstack {
-			printf(site, "%s from %s", site.Description(), site.Caller().Func())
+		for i := len(r.callpath) - 1; i >= 0; i-- {
+			edge := r.callpath[i]
+			printf(edge.Site, "%s from %s", edge.Site.Common().Description(), edge.Caller.Func())
 		}
 	} else {
 		printf(r.target, "%s is unreachable in this analysis scope", r.target)
@@ -100,11 +79,12 @@ func (r *callstackResult) display(printf printfFunc) {
 
 func (r *callstackResult) toSerial(res *serial.Result, fset *token.FileSet) {
 	var callers []serial.Caller
-	for _, site := range r.callstack {
+	for i := len(r.callpath) - 1; i >= 0; i-- { // (innermost first)
+		edge := r.callpath[i]
 		callers = append(callers, serial.Caller{
-			Pos:    fset.Position(site.Pos()).String(),
-			Caller: site.Caller().Func().String(),
-			Desc:   site.Description(),
+			Pos:    fset.Position(edge.Site.Pos()).String(),
+			Caller: edge.Caller.Func().String(),
+			Desc:   edge.Site.Common().Description(),
 		})
 	}
 	res.Callstack = &serial.CallStack{
diff --git a/oracle/describe.go b/oracle/describe.go
index 20941915..23da2175 100644
--- a/oracle/describe.go
+++ b/oracle/describe.go
@@ -419,11 +419,11 @@ func describePointer(o *Oracle, v ssa.Value, indirect bool) (ptrs []pointerResul
 	buildSSA(o)
 
 	// TODO(adonovan): don't run indirect pointer analysis on non-ptr-ptrlike types.
-	o.config.QueryValues = map[ssa.Value]pointer.Indirect{v: pointer.Indirect(indirect)}
-	ptrAnalysis(o)
+	o.config.Queries = map[ssa.Value]pointer.Indirect{v: pointer.Indirect(indirect)}
+	ptares := ptrAnalysis(o)
 
 	// Combine the PT sets from all contexts.
-	pointers := o.config.QueryResults[v]
+	pointers := ptares.Queries[v]
 	if pointers == nil {
 		return nil, fmt.Errorf("PTA did not encounter this expression (dead code?)")
 	}
diff --git a/oracle/oracle.go b/oracle/oracle.go
index f3b6781c..3c0a7510 100644
--- a/oracle/oracle.go
+++ b/oracle/oracle.go
@@ -358,14 +358,12 @@ func buildSSA(o *Oracle) {
 	o.timers["SSA-build"] = time.Since(start)
 }
 
-// ptrAnalysis runs the pointer analysis and returns the synthetic
-// root of the callgraph.
-//
-func ptrAnalysis(o *Oracle) pointer.CallGraphNode {
+// ptrAnalysis runs the pointer analysis and returns its result.
+func ptrAnalysis(o *Oracle) *pointer.Result {
 	start := time.Now()
-	root := pointer.Analyze(&o.config)
+	result := pointer.Analyze(&o.config)
 	o.timers["pointer analysis"] = time.Since(start)
-	return root
+	return result
 }
 
 // parseOctothorpDecimal returns the numeric value if s matches "#%d",
diff --git a/oracle/peers.go b/oracle/peers.go
index 41010ae6..65e7ac2d 100644
--- a/oracle/peers.go
+++ b/oracle/peers.go
@@ -71,11 +71,11 @@ func peers(o *Oracle, qpos *QueryPos) (queryResult, error) {
 	ops = ops[:i]
 
 	// Run the pointer analysis.
-	o.config.QueryValues = channels
-	ptrAnalysis(o)
+	o.config.Queries = channels
+	ptares := ptrAnalysis(o)
 
 	// Combine the PT sets from all contexts.
-	queryChanPts := pointer.PointsToCombined(o.config.QueryResults[queryOp.ch])
+	queryChanPts := pointer.PointsToCombined(ptares.Queries[queryOp.ch])
 
 	// Ascertain which make(chan) labels the query's channel can alias.
 	var makes []token.Pos
@@ -87,7 +87,7 @@ func peers(o *Oracle, qpos *QueryPos) (queryResult, error) {
 	// Ascertain which send/receive operations can alias the same make(chan) labels.
 	var sends, receives []token.Pos
 	for _, op := range ops {
-		for _, ptr := range o.config.QueryResults[op.ch] {
+		for _, ptr := range ptares.Queries[op.ch] {
 			if ptr != nil && ptr.PointsTo().Intersects(queryChanPts) {
 				if op.dir == ast.SEND {
 					sends = append(sends, op.pos)
diff --git a/oracle/testdata/src/main/calls.golden b/oracle/testdata/src/main/calls.golden
index 259a7980..8ba18e8d 100644
--- a/oracle/testdata/src/main/calls.golden
+++ b/oracle/testdata/src/main/calls.golden
@@ -88,7 +88,7 @@ dynamic method call on nil value
 
 -------- @callees callees-err-deadcode2 --------
 
-Error: this call site is unreachable in this analysis
+Error: this function is unreachable in this analysis
 -------- @callstack callstack-err-deadcode --------
 main.deadcode is unreachable in this analysis scope
 
diff --git a/pointer/TODO b/pointer/TODO
index d5f12bc7..10afd49a 100644
--- a/pointer/TODO
+++ b/pointer/TODO
@@ -32,12 +32,6 @@ SOLVER:
   dannyb recommends sparse bitmap.
 
 API:
-- Rely less on callbacks and more on a 'result' type
-  returned by Analyze().
-- Abstract the callgraph into a pure interface so that 
-  we can provide other implementations in future (e.g. RTA-based).
-  Also provide the option to eliminate context-sensitivity
-  in a callgraph to yield a smaller (less precise) callgraph.
 - Some optimisations (e.g. LE, PE) may change the API.
   Think about them sooner rather than later.
 - Eliminate Print probe now that we can query specific ssa.Values.
diff --git a/pointer/analysis.go b/pointer/analysis.go
index b825bb11..d645365f 100644
--- a/pointer/analysis.go
+++ b/pointer/analysis.go
@@ -173,13 +173,14 @@ type analysis struct {
 	nodes       []*node                     // indexed by nodeid
 	flattenMemo map[types.Type][]*fieldInfo // memoization of flatten()
 	constraints []constraint                // set of constraints
-	callsites   []*callsite                 // all callsites
+	cgnodes     []*cgnode                   // all cgnodes
 	genq        []*cgnode                   // queue of functions to generate constraints for
 	intrinsics  map[*ssa.Function]intrinsic // non-nil values are summaries for intrinsic fns
 	funcObj     map[*ssa.Function]nodeid    // default function object for each func
 	probes      map[*ssa.CallCommon]nodeid  // maps call to print() to argument variable
 	valNode     map[ssa.Value]nodeid        // node for each ssa.Value
 	work        worklist                    // solver's worklist
+	queries     map[ssa.Value][]Pointer     // same as Results.Queries
 
 	// Reflection:
 	hasher          typemap.Hasher // cache of type hashes
@@ -229,7 +230,7 @@ func (a *analysis) warnf(pos token.Pos, format string, args ...interface{}) {
 // Analyze runs the pointer analysis with the scope and options
 // specified by config, and returns the (synthetic) root of the callgraph.
 //
-func Analyze(config *Config) CallGraphNode {
+func Analyze(config *Config) *Result {
 	a := &analysis{
 		config:      config,
 		log:         config.Log,
@@ -241,6 +242,7 @@ func Analyze(config *Config) CallGraphNode {
 		funcObj:     make(map[*ssa.Function]nodeid),
 		probes:      make(map[*ssa.CallCommon]nodeid),
 		work:        makeMapWorklist(),
+		queries:     make(map[ssa.Value][]Pointer),
 	}
 
 	if reflect := a.prog.ImportedPackage("reflect"); reflect != nil {
@@ -265,7 +267,7 @@ func Analyze(config *Config) CallGraphNode {
 		fmt.Fprintln(a.log, "======== NEW ANALYSIS ========")
 	}
 
-	root := a.generate()
+	a.generate()
 
 	//a.optimize()
 
@@ -280,32 +282,33 @@ func Analyze(config *Config) CallGraphNode {
 		}
 	}
 
-	// Notify the client of the callsites if they're interested.
-	if CallSite := a.config.CallSite; CallSite != nil {
-		for _, site := range a.callsites {
-			CallSite(site)
-		}
-	}
+	// Visit discovered call graph.
+	for _, caller := range a.cgnodes {
+		for _, site := range caller.sites {
+			for nid := range a.nodes[site.targets].pts {
+				callee := a.nodes[nid].obj.cgn
 
-	Call := a.config.Call
-	for _, site := range a.callsites {
-		for nid := range a.nodes[site.targets].pts {
-			cgn := a.nodes[nid].obj.cgn
+				if a.config.BuildCallGraph {
+					site.callees = append(site.callees, callee)
+				}
 
-			// Notify the client of the call graph, if
-			// they're interested.
-			if Call != nil {
-				Call(site, cgn)
-			}
-
-			// Warn about calls to non-intrinsic external functions.
-
-			if fn := cgn.fn; fn.Blocks == nil && a.findIntrinsic(fn) == nil {
-				a.warnf(site.Pos(), "unsound call to unknown intrinsic: %s", fn)
-				a.warnf(fn.Pos(), " (declared here)")
+				// TODO(adonovan): de-dup these messages.
+				// Warn about calls to non-intrinsic external functions.
+				if fn := callee.fn; fn.Blocks == nil && a.findIntrinsic(fn) == nil {
+					a.warnf(site.pos(), "unsound call to unknown intrinsic: %s", fn)
+					a.warnf(fn.Pos(), " (declared here)")
+				}
 			}
 		}
 	}
 
-	return root
+	var callgraph *cgraph
+	if a.config.BuildCallGraph {
+		callgraph = &cgraph{a.cgnodes}
+	}
+
+	return &Result{
+		CallGraph: callgraph,
+		Queries:   a.queries,
+	}
 }
diff --git a/pointer/api.go b/pointer/api.go
index f1f4e472..3867b2a4 100644
--- a/pointer/api.go
+++ b/pointer/api.go
@@ -9,6 +9,7 @@ import (
 	"go/token"
 	"io"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/go/types/typemap"
 	"code.google.com/p/go.tools/ssa"
 )
@@ -27,31 +28,12 @@ type Config struct {
 	// has not yet been reduced by presolver optimisation.
 	Reflection bool
 
+	// BuildCallGraph determines whether to construct a callgraph.
+	// If enabled, the graph will be available in Result.CallGraph.
+	BuildCallGraph bool
+
 	// -------- Optional callbacks invoked by the analysis --------
 
-	// Call is invoked for each discovered call-graph edge.  The
-	// call-graph is a multigraph over CallGraphNodes with edges
-	// labelled by the CallSite that gives rise to the edge.
-	// (The caller node is available as site.Caller())
-	//
-	// Clients that wish to construct a call graph may provide
-	// CallGraph.AddEdge here.
-	//
-	// The callgraph may be context-sensitive, i.e. it may
-	// distinguish separate calls to the same function depending
-	// on the context.
-	//
-	Call func(site CallSite, callee CallGraphNode)
-
-	// CallSite is invoked for each call-site encountered in the
-	// program.
-	//
-	// The callgraph may be context-sensitive, i.e. it may
-	// distinguish separate calls to the same function depending
-	// on the context.
-	//
-	CallSite func(site CallSite)
-
 	// Warn is invoked for each warning encountered by the analysis,
 	// e.g. unknown external function, unsound use of unsafe.Pointer.
 	// pos may be zero if the position is not known.
@@ -71,8 +53,8 @@ type Config struct {
 	//
 	Print func(site *ssa.CallCommon, p Pointer)
 
-	// The client populates QueryValues[v] for each ssa.Value v
-	// of interest.
+	// The client populates Queries[v] for each ssa.Value v of
+	// interest.
 	//
 	// The boolean (Indirect) indicates whether to compute the
 	// points-to set for v (false) or *v (true): the latter is
@@ -80,20 +62,16 @@ type Config struct {
 	// lvalues, e.g. an *ssa.Global.
 	//
 	// The pointer analysis will populate the corresponding
-	// QueryResults value when it creates the pointer variable
-	// for v or *v.  Upon completion the client can inspect the
+	// Results.Queries value when it creates the pointer variable
+	// for v or *v.  Upon completion the client can inspect that
 	// map for the results.
 	//
 	// If a Value belongs to a function that the analysis treats
-	// context-sensitively, the corresponding QueryResults slice
+	// context-sensitively, the corresponding Results.Queries slice
 	// may have multiple Pointers, one per distinct context.  Use
 	// PointsToCombined to merge them.
 	//
-	// TODO(adonovan): refactor the API: separate all results of
-	// Analyze() into a dedicated Result struct.
-	//
-	QueryValues  map[ssa.Value]Indirect
-	QueryResults map[ssa.Value][]Pointer
+	Queries map[ssa.Value]Indirect
 
 	// -------- Other configuration options --------
 
@@ -111,10 +89,19 @@ func (c *Config) prog() *ssa.Program {
 	panic("empty scope")
 }
 
+// A Result contains the results of a pointer analysis.
+//
+// See Config for how to request the various Result components.
+//
+type Result struct {
+	CallGraph call.Graph              // discovered call graph
+	Queries   map[ssa.Value][]Pointer // points-to sets for queried ssa.Values
+}
+
 // A Pointer is an equivalence class of pointerlike values.
 //
 // TODO(adonovan): add a method
-//    Context() CallGraphNode
+//    Context() call.GraphNode
 // for pointers corresponding to local variables,
 //
 type Pointer interface {
diff --git a/pointer/callgraph.go b/pointer/callgraph.go
index af328a9e..e3d8bcea 100644
--- a/pointer/callgraph.go
+++ b/pointer/callgraph.go
@@ -4,116 +4,93 @@
 
 package pointer
 
+// This file defines our implementation of the call.Graph API.
+
 import (
 	"fmt"
 	"go/token"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/ssa"
 )
 
-// TODO(adonovan): move the CallGraph, CallGraphNode, CallSite types
-// into a separate package 'callgraph', and make them pure interfaces
-// capable of supporting several implementations (context-sensitive
-// and insensitive PTA, RTA, etc).
-
-// ---------- CallGraphNode ----------
-
-// A CallGraphNode is a context-sensitive representation of a node in
-// the callgraph.  In other words, there may be multiple nodes
-// representing a single *Function, depending on the contexts in which
-// it is called.  The identity of the node is therefore important.
-//
-type CallGraphNode interface {
-	Func() *ssa.Function // the function this node represents
-	String() string      // diagnostic description of this callgraph node
+// cgraph implements call.Graph.
+type cgraph struct {
+	nodes []*cgnode
 }
 
+func (g *cgraph) Nodes() []call.GraphNode {
+	nodes := make([]call.GraphNode, len(g.nodes))
+	for i, node := range g.nodes {
+		nodes[i] = node
+	}
+	return nodes
+}
+
+func (g *cgraph) Root() call.GraphNode {
+	return g.nodes[0]
+}
+
+// cgnode implements call.GraphNode.
 type cgnode struct {
-	fn  *ssa.Function
-	obj nodeid // start of this contour's object block
+	fn    *ssa.Function
+	obj   nodeid      // start of this contour's object block
+	sites []*callsite // ordered list of callsites within this function
 }
 
 func (n *cgnode) Func() *ssa.Function {
 	return n.fn
 }
 
+func (n *cgnode) Sites() []ssa.CallInstruction {
+	sites := make([]ssa.CallInstruction, len(n.sites))
+	for i, site := range n.sites {
+		sites[i] = site.instr
+	}
+	return sites
+}
+
+func (n *cgnode) Edges() []call.Edge {
+	var numEdges int
+	for _, site := range n.sites {
+		numEdges += len(site.callees)
+	}
+	edges := make([]call.Edge, 0, numEdges)
+
+	for _, site := range n.sites {
+		for _, callee := range site.callees {
+			edges = append(edges, call.Edge{Caller: n, Site: site.instr, Callee: callee})
+		}
+	}
+	return edges
+}
+
 func (n *cgnode) String() string {
 	return fmt.Sprintf("cg%d:%s", n.obj, n.fn)
 }
 
-// ---------- CallSite ----------
-
-// A CallSite is a context-sensitive representation of a function call
-// site in the program.
-//
-type CallSite interface {
-	Caller() CallGraphNode // the enclosing context of this call
-	Pos() token.Pos        // source position; token.NoPos for synthetic calls
-	Description() string   // UI description of call kind; see (*ssa.CallCommon).Description
-	String() string        // diagnostic description of this callsite
-}
-
-// A callsite represents a single function or method callsite within a
-// function.  callsites never represent calls to built-ins; they are
-// handled as intrinsics.
+// A callsite represents a single call site within a cgnode;
+// it is implicitly context-sensitive.
+// callsites never represent calls to built-ins;
+// they are handled as intrinsics.
 //
 type callsite struct {
-	caller  *cgnode             // the origin of the call
 	targets nodeid              // pts(targets) contains identities of all called functions.
-	instr   ssa.CallInstruction // optional call instruction; provides IsInvoke, position, etc.
-	pos     token.Pos           // position, if instr == nil, i.e. synthetic callsites.
+	instr   ssa.CallInstruction // the call instruction; nil for synthetic/intrinsic
+	callees []*cgnode           // unordered set of callees of this site
 }
 
-// Caller returns the node in the callgraph from which this call originated.
-func (c *callsite) Caller() CallGraphNode {
-	return c.caller
-}
-
-// Description returns a description of this kind of call, in the
-// manner of ssa.CallCommon.Description().
-//
-func (c *callsite) Description() string {
+func (c *callsite) String() string {
 	if c.instr != nil {
 		return c.instr.Common().Description()
 	}
 	return "synthetic function call"
 }
 
-// Pos returns the source position of this callsite, or token.NoPos if implicit.
-func (c *callsite) Pos() token.Pos {
+// pos returns the source position of this callsite, or token.NoPos if implicit.
+func (c *callsite) pos() token.Pos {
 	if c.instr != nil {
 		return c.instr.Pos()
 	}
-	return c.pos
-}
-
-func (c *callsite) String() string {
-	// TODO(adonovan): provide more info, e.g. target of static
-	// call, arguments, location.
-	return c.Description()
-}
-
-// ---------- CallGraph ----------
-
-// CallGraph is a forward directed graph of functions labelled by an
-// arbitrary site within the caller.
-//
-// CallGraph.AddEdge may be used as the Context.Call callback for
-// clients that wish to construct a call graph.
-//
-// TODO(adonovan): this is just a starting point.  Add options to
-// control whether we record no callsite, an arbitrary callsite, or
-// all callsites for a given graph edge.  Also, this could live in
-// another package since it's just a client utility.
-//
-type CallGraph map[CallGraphNode]map[CallGraphNode]CallSite
-
-func (cg CallGraph) AddEdge(site CallSite, callee CallGraphNode) {
-	caller := site.Caller()
-	callees := cg[caller]
-	if callees == nil {
-		callees = make(map[CallGraphNode]CallSite)
-		cg[caller] = callees
-	}
-	callees[callee] = site // save an arbitrary site
+	return token.NoPos
 }
diff --git a/pointer/example_test.go b/pointer/example_test.go
index fae61954..bd86818a 100644
--- a/pointer/example_test.go
+++ b/pointer/example_test.go
@@ -10,6 +10,7 @@ import (
 	"go/parser"
 	"sort"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/importer"
 	"code.google.com/p/go.tools/pointer"
 	"code.google.com/p/go.tools/ssa"
@@ -66,34 +67,23 @@ func main() {
 	prog.BuildAll()
 
 	// Run the pointer analysis and build the complete callgraph.
-	callgraph := make(pointer.CallGraph)
 	config := &pointer.Config{
-		Mains: []*ssa.Package{mainPkg},
-		Call:  callgraph.AddEdge,
+		Mains:          []*ssa.Package{mainPkg},
+		BuildCallGraph: true,
 	}
-	root := pointer.Analyze(config)
+	result := pointer.Analyze(config)
 
-	// Visit callgraph in depth-first order.
-	//
-	// There may be multiple nodes for the
-	// same function due to context sensitivity.
-	var edges []string // call edges originating from the main package.
-	seen := make(map[pointer.CallGraphNode]bool)
-	var visit func(cgn pointer.CallGraphNode)
-	visit = func(cgn pointer.CallGraphNode) {
-		if seen[cgn] {
-			return // already seen
+	// Find edges originating from the main package.
+	// By converting to strings, we de-duplicate nodes
+	// representing the same function due to context sensitivity.
+	var edges []string
+	call.GraphVisitEdges(result.CallGraph, func(edge call.Edge) error {
+		caller := edge.Caller.Func()
+		if caller.Pkg == mainPkg {
+			edges = append(edges, fmt.Sprint(caller, " --> ", edge.Callee.Func()))
 		}
-		seen[cgn] = true
-		caller := cgn.Func()
-		for callee := range callgraph[cgn] {
-			if caller.Pkg == mainPkg {
-				edges = append(edges, fmt.Sprint(caller, " --> ", callee.Func()))
-			}
-			visit(callee)
-		}
-	}
-	visit(root)
+		return nil
+	})
 
 	// Print the edges in sorted order.
 	sort.Strings(edges)
diff --git a/pointer/gen.go b/pointer/gen.go
index 62fb1039..cebeff5a 100644
--- a/pointer/gen.go
+++ b/pointer/gen.go
@@ -72,18 +72,13 @@ func (a *analysis) setValueNode(v ssa.Value, id nodeid) {
 	}
 
 	// Record the (v, id) relation if the client has queried v.
-	if indirect, ok := a.config.QueryValues[v]; ok {
+	if indirect, ok := a.config.Queries[v]; ok {
 		if indirect {
 			tmp := a.addNodes(v.Type(), "query.indirect")
 			a.load(tmp, id, a.sizeof(v.Type()))
 			id = tmp
 		}
-		ptrs := a.config.QueryResults
-		if ptrs == nil {
-			ptrs = make(map[ssa.Value][]Pointer)
-			a.config.QueryResults = ptrs
-		}
-		ptrs[v] = append(ptrs[v], ptr{a, id})
+		a.queries[v] = append(a.queries[v], ptr{a, id})
 	}
 }
 
@@ -125,7 +120,7 @@ func (a *analysis) makeFunctionObject(fn *ssa.Function) nodeid {
 
 	// obj is the function object (identity, params, results).
 	obj := a.nextNode()
-	cgn := &cgnode{fn: fn, obj: obj}
+	cgn := a.makeCGNode(fn, obj)
 	sig := fn.Signature
 	a.addOneNode(sig, "func.cgnode", nil) // (scalar with Signature type)
 	if recv := sig.Recv(); recv != nil {
@@ -849,15 +844,12 @@ func (a *analysis) genCall(caller *cgnode, instr ssa.CallInstruction) {
 	}
 
 	site := &callsite{
-		caller:  caller,
 		targets: targets,
 		instr:   instr,
-		pos:     instr.Pos(),
 	}
-	a.callsites = append(a.callsites, site)
+	caller.sites = append(caller.sites, site)
 	if a.log != nil {
-		fmt.Fprintf(a.log, "\t%s to targets %s from %s\n",
-			site.Description(), site.targets, site.caller)
+		fmt.Fprintf(a.log, "\t%s to targets %s from %s\n", site, site.targets, caller)
 	}
 }
 
@@ -1061,6 +1053,12 @@ func (a *analysis) genInstr(cgn *cgnode, instr ssa.Instruction) {
 	}
 }
 
+func (a *analysis) makeCGNode(fn *ssa.Function, obj nodeid) *cgnode {
+	cgn := &cgnode{fn: fn, obj: obj}
+	a.cgnodes = append(a.cgnodes, cgn)
+	return cgn
+}
+
 // genRootCalls generates the synthetic root of the callgraph and the
 // initial calls from it to the analysis scope, such as main, a test
 // or a library.
@@ -1070,7 +1068,7 @@ func (a *analysis) genRootCalls() *cgnode {
 	r.Prog = a.prog // hack.
 	r.Enclosing = r // hack, so Function.String() doesn't crash
 	r.String()      // (asserts that it doesn't crash)
-	root := &cgnode{fn: r}
+	root := a.makeCGNode(r, 0)
 
 	// For each main package, call main.init(), main.main().
 	for _, mainPkg := range a.config.Mains {
@@ -1080,11 +1078,8 @@ func (a *analysis) genRootCalls() *cgnode {
 		}
 
 		targets := a.addOneNode(main.Signature, "root.targets", nil)
-		site := &callsite{
-			caller:  root,
-			targets: targets,
-		}
-		a.callsites = append(a.callsites, site)
+		site := &callsite{targets: targets}
+		root.sites = append(root.sites, site)
 		for _, fn := range [2]*ssa.Function{mainPkg.Func("init"), main} {
 			if a.log != nil {
 				fmt.Fprintf(a.log, "\troot call to %s:\n", fn)
diff --git a/pointer/labels.go b/pointer/labels.go
index 6f33f1fa..215d24c9 100644
--- a/pointer/labels.go
+++ b/pointer/labels.go
@@ -9,6 +9,7 @@ import (
 	"go/token"
 	"strings"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/go/types"
 	"code.google.com/p/go.tools/ssa"
 )
@@ -46,7 +47,7 @@ func (l Label) Value() ssa.Value {
 // Context returns the analytic context in which this label's object was allocated,
 // or nil for global objects: global, const, and shared contours for functions.
 //
-func (l Label) Context() CallGraphNode {
+func (l Label) Context() call.GraphNode {
 	return l.obj.cgn
 }
 
diff --git a/pointer/pointer_test.go b/pointer/pointer_test.go
index 8799e719..7f4a500c 100644
--- a/pointer/pointer_test.go
+++ b/pointer/pointer_test.go
@@ -10,6 +10,7 @@ package pointer_test
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"go/build"
 	"go/parser"
@@ -21,6 +22,7 @@ import (
 	"strings"
 	"testing"
 
+	"code.google.com/p/go.tools/call"
 	"code.google.com/p/go.tools/go/types"
 	"code.google.com/p/go.tools/go/types/typemap"
 	"code.google.com/p/go.tools/importer"
@@ -286,24 +288,22 @@ func doOneInput(input, filename string) bool {
 	var warnings []string
 	var log bytes.Buffer
 
-	callgraph := make(pointer.CallGraph)
-
 	// Run the analysis.
 	config := &pointer.Config{
-		Reflection: true,
-		Mains:      []*ssa.Package{ptrmain},
-		Log:        &log,
+		Reflection:     true,
+		BuildCallGraph: true,
+		Mains:          []*ssa.Package{ptrmain},
+		Log:            &log,
 		Print: func(site *ssa.CallCommon, p pointer.Pointer) {
 			probes = append(probes, probe{site, p})
 		},
-		Call: callgraph.AddEdge,
 		Warn: func(pos token.Pos, format string, args ...interface{}) {
 			msg := fmt.Sprintf(format, args...)
 			fmt.Printf("%s: warning: %s\n", prog.Fset.Position(pos), msg)
 			warnings = append(warnings, msg)
 		},
 	}
-	pointer.Analyze(config)
+	result := pointer.Analyze(config)
 
 	// Print the log is there was an error or a panic.
 	complete := false
@@ -341,7 +341,7 @@ func doOneInput(input, filename string) bool {
 			}
 
 		case "calls":
-			if !checkCallsExpectation(prog, e, callgraph) {
+			if !checkCallsExpectation(prog, e, result.CallGraph) {
 				ok = false
 			}
 
@@ -463,29 +463,33 @@ func checkTypesExpectation(e *expectation, pr *probe) bool {
 		e.errorf("interface may additionally contain these types: %s", surplus.KeysString())
 	}
 	return ok
-	return false
 }
 
-func checkCallsExpectation(prog *ssa.Program, e *expectation, callgraph pointer.CallGraph) bool {
-	// TODO(adonovan): this is inefficient and not robust against
-	// typos.  Better to convert strings to *Functions during
-	// expectation parsing (somehow).
-	for caller, callees := range callgraph {
-		if caller.Func().String() == e.args[0] {
-			found := make(map[string]struct{})
-			for callee := range callees {
-				s := callee.Func().String()
-				found[s] = struct{}{}
-				if s == e.args[1] {
-					return true // expectation satisfied
-				}
+var errOK = errors.New("OK")
+
+func checkCallsExpectation(prog *ssa.Program, e *expectation, callgraph call.Graph) bool {
+	found := make(map[string]struct{})
+	err := call.GraphVisitEdges(callgraph, func(edge call.Edge) error {
+		// Name-based matching is inefficient but it allows us to
+		// match functions whose names that would not appear in an
+		// index ("<root>") or which are not unique ("func@1.2").
+		if edge.Caller.Func().String() == e.args[0] {
+			calleeStr := edge.Callee.Func().String()
+			if calleeStr == e.args[1] {
+				return errOK // expectation satisified; stop the search
 			}
-			e.errorf("found no call from %s to %s, but only to %s",
-				e.args[0], e.args[1], join(found))
-			return false
+			found[calleeStr] = struct{}{}
 		}
+		return nil
+	})
+	if err == errOK {
+		return true
 	}
-	e.errorf("didn't find any calls from %s", e.args[0])
+	if len(found) == 0 {
+		e.errorf("didn't find any calls from %s", e.args[0])
+	}
+	e.errorf("found no call from %s to %s, but only to %s",
+		e.args[0], e.args[1], join(found))
 	return false
 }