cmd/vendor/github.com/google/pprof: refresh from upstream

Update vendored pprof to commit 4fc39a00b6b8c1aad05260f01429ec70e127252c
from github.com/google/pprof (2017-11-01).

Fixes #19380
Updates #21047

Change-Id: Ib64a94a45209039e5945acbcfa0392790c8ee41e
Reviewed-on: https://go-review.googlesource.com/57370
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

10 files changed, 168 insertions, 100 deletions

diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph.go b/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph.go
index c99e8992de..4e5d12f6cd 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph.go
@@ -42,15 +42,17 @@ type DotNodeAttributes struct {
 // DotConfig contains attributes about how a graph should be
 // constructed and how it should look.
 type DotConfig struct {
-	Title  string   // The title of the DOT graph
-	Labels []string // The labels for the DOT's legend
+	Title     string   // The title of the DOT graph
+	LegendURL string   // The URL to link to from the legend.
+	Labels    []string // The labels for the DOT's legend
 
-	FormatValue func(int64) string         // A formatting function for values
-	FormatTag   func(int64, string) string // A formatting function for numeric tags
-	Total       int64                      // The total weight of the graph, used to compute percentages
+	FormatValue func(int64) string // A formatting function for values
+	Total       int64              // The total weight of the graph, used to compute percentages
 }
 
-// Compose creates and writes a in the DOT format to the writer, using
+const maxNodelets = 4 // Number of nodelets for labels (both numeric and non)
+
+// ComposeDot creates and writes a in the DOT format to the writer, using
 // the configurations given.
 func ComposeDot(w io.Writer, g *Graph, a *DotAttributes, c *DotConfig) {
 	builder := &builder{w, a, c}
@@ -120,11 +122,19 @@ func (b *builder) finish() {
 // addLegend generates a legend in DOT format.
 func (b *builder) addLegend() {
 	labels := b.config.Labels
-	var title string
-	if len(labels) > 0 {
-		title = labels[0]
+	if len(labels) == 0 {
+		return
+	}
+	title := labels[0]
+	fmt.Fprintf(b, `subgraph cluster_L { "%s" [shape=box fontsize=16`, title)
+	fmt.Fprintf(b, ` label="%s\l"`, strings.Join(labels, `\l`))
+	if b.config.LegendURL != "" {
+		fmt.Fprintf(b, ` URL="%s" target="_blank"`, b.config.LegendURL)
+	}
+	if b.config.Title != "" {
+		fmt.Fprintf(b, ` tooltip="%s"`, b.config.Title)
 	}
-	fmt.Fprintf(b, `subgraph cluster_L { "%s" [shape=box fontsize=16 label="%s\l"] }`+"\n", title, strings.Join(labels, `\l`))
+	fmt.Fprintf(b, "] }\n")
 }
 
 // addNode generates a graph node in DOT format.
@@ -176,8 +186,8 @@ func (b *builder) addNode(node *Node, nodeID int, maxFlat float64) {
 	}
 
 	// Create DOT attribute for node.
-	attr := fmt.Sprintf(`label="%s" fontsize=%d shape=%s tooltip="%s (%s)" color="%s" fillcolor="%s"`,
-		label, fontSize, shape, node.Info.PrintableName(), cumValue,
+	attr := fmt.Sprintf(`label="%s" id="node%d" fontsize=%d shape=%s tooltip="%s (%s)" color="%s" fillcolor="%s"`,
+		label, nodeID, fontSize, shape, node.Info.PrintableName(), cumValue,
 		dotColor(float64(node.CumValue())/float64(abs64(b.config.Total)), false),
 		dotColor(float64(node.CumValue())/float64(abs64(b.config.Total)), true))
 
@@ -204,13 +214,11 @@ func (b *builder) addNode(node *Node, nodeID int, maxFlat float64) {
 
 // addNodelets generates the DOT boxes for the node tags if they exist.
 func (b *builder) addNodelets(node *Node, nodeID int) bool {
-	const maxNodelets = 4    // Number of nodelets for alphanumeric labels
-	const maxNumNodelets = 4 // Number of nodelets for numeric labels
 	var nodelets string
 
 	// Populate two Tag slices, one for LabelTags and one for NumericTags.
 	var ts []*Tag
-	lnts := make(map[string][]*Tag, 0)
+	lnts := make(map[string][]*Tag)
 	for _, t := range node.LabelTags {
 		ts = append(ts, t)
 	}
@@ -239,15 +247,15 @@ func (b *builder) addNodelets(node *Node, nodeID int) bool {
 			continue
 		}
 		weight := b.config.FormatValue(w)
-		nodelets += fmt.Sprintf(`N%d_%d [label = "%s" fontsize=8 shape=box3d tooltip="%s"]`+"\n", nodeID, i, t.Name, weight)
+		nodelets += fmt.Sprintf(`N%d_%d [label = "%s" id="N%d_%d" fontsize=8 shape=box3d tooltip="%s"]`+"\n", nodeID, i, t.Name, nodeID, i, weight)
 		nodelets += fmt.Sprintf(`N%d -> N%d_%d [label=" %s" weight=100 tooltip="%s" labeltooltip="%s"]`+"\n", nodeID, nodeID, i, weight, weight, weight)
 		if nts := lnts[t.Name]; nts != nil {
-			nodelets += b.numericNodelets(nts, maxNumNodelets, flatTags, fmt.Sprintf(`N%d_%d`, nodeID, i))
+			nodelets += b.numericNodelets(nts, maxNodelets, flatTags, fmt.Sprintf(`N%d_%d`, nodeID, i))
 		}
 	}
 
 	if nts := lnts[""]; nts != nil {
-		nodelets += b.numericNodelets(nts, maxNumNodelets, flatTags, fmt.Sprintf(`N%d`, nodeID))
+		nodelets += b.numericNodelets(nts, maxNodelets, flatTags, fmt.Sprintf(`N%d`, nodeID))
 	}
 
 	fmt.Fprint(b, nodelets)
@@ -266,7 +274,7 @@ func (b *builder) numericNodelets(nts []*Tag, maxNumNodelets int, flatTags bool,
 		}
 		if w != 0 {
 			weight := b.config.FormatValue(w)
-			nodelets += fmt.Sprintf(`N%s_%d [label = "%s" fontsize=8 shape=box3d tooltip="%s"]`+"\n", source, j, t.Name, weight)
+			nodelets += fmt.Sprintf(`N%s_%d [label = "%s" id="N%s_%d" fontsize=8 shape=box3d tooltip="%s"]`+"\n", source, j, t.Name, source, j, weight)
 			nodelets += fmt.Sprintf(`%s -> N%s_%d [label=" %s" weight=100 tooltip="%s" labeltooltip="%s"%s]`+"\n", source, source, j, weight, weight, weight, attr)
 		}
 	}
@@ -441,14 +449,9 @@ func tagDistance(t, u *Tag) float64 {
 }
 
 func (b *builder) tagGroupLabel(g []*Tag) (label string, flat, cum int64) {
-	formatTag := b.config.FormatTag
-	if formatTag == nil {
-		formatTag = measurement.Label
-	}
-
 	if len(g) == 1 {
 		t := g[0]
-		return formatTag(t.Value, t.Unit), t.FlatValue(), t.CumValue()
+		return measurement.Label(t.Value, t.Unit), t.FlatValue(), t.CumValue()
 	}
 	min := g[0]
 	max := g[0]
@@ -472,7 +475,11 @@ func (b *builder) tagGroupLabel(g []*Tag) (label string, flat, cum int64) {
 	if dc != 0 {
 		c = c / dc
 	}
-	return formatTag(min.Value, min.Unit) + ".." + formatTag(max.Value, max.Unit), f, c
+
+	// Tags are not scaled with the selected output unit because tags are often
+	// much smaller than other values which appear, so the range of tag sizes
+	// sometimes would appear to be "0..0" when scaled to the selected output unit.
+	return measurement.Label(min.Value, min.Unit) + ".." + measurement.Label(max.Value, max.Unit), f, c
 }
 
 func min64(a, b int64) int64 {
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph_test.go b/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph_test.go
index 7f51269769..b8368b8fa4 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph_test.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/dotgraph_test.go
@@ -16,8 +16,10 @@ package graph
 
 import (
 	"bytes"
+	"flag"
 	"fmt"
 	"io/ioutil"
+	"path/filepath"
 	"reflect"
 	"strconv"
 	"strings"
@@ -26,7 +28,7 @@ import (
 	"github.com/google/pprof/internal/proftest"
 )
 
-const path = "testdata/"
+var updateFlag = flag.Bool("update", false, "Update the golden files")
 
 func TestComposeWithStandardGraph(t *testing.T) {
 	g := baseGraph()
@@ -35,12 +37,7 @@ func TestComposeWithStandardGraph(t *testing.T) {
 	var buf bytes.Buffer
 	ComposeDot(&buf, g, a, c)
 
-	want, err := ioutil.ReadFile(path + "compose1.dot")
-	if err != nil {
-		t.Fatalf("error reading test file: %v", err)
-	}
-
-	compareGraphs(t, buf.Bytes(), want)
+	compareGraphs(t, buf.Bytes(), "compose1.dot")
 }
 
 func TestComposeWithNodeAttributesAndZeroFlat(t *testing.T) {
@@ -64,12 +61,7 @@ func TestComposeWithNodeAttributesAndZeroFlat(t *testing.T) {
 	var buf bytes.Buffer
 	ComposeDot(&buf, g, a, c)
 
-	want, err := ioutil.ReadFile(path + "compose2.dot")
-	if err != nil {
-		t.Fatalf("error reading test file: %v", err)
-	}
-
-	compareGraphs(t, buf.Bytes(), want)
+	compareGraphs(t, buf.Bytes(), "compose2.dot")
 }
 
 func TestComposeWithTagsAndResidualEdge(t *testing.T) {
@@ -97,12 +89,7 @@ func TestComposeWithTagsAndResidualEdge(t *testing.T) {
 	var buf bytes.Buffer
 	ComposeDot(&buf, g, a, c)
 
-	want, err := ioutil.ReadFile(path + "compose3.dot")
-	if err != nil {
-		t.Fatalf("error reading test file: %v", err)
-	}
-
-	compareGraphs(t, buf.Bytes(), want)
+	compareGraphs(t, buf.Bytes(), "compose3.dot")
 }
 
 func TestComposeWithNestedTags(t *testing.T) {
@@ -127,12 +114,7 @@ func TestComposeWithNestedTags(t *testing.T) {
 	var buf bytes.Buffer
 	ComposeDot(&buf, g, a, c)
 
-	want, err := ioutil.ReadFile(path + "compose5.dot")
-	if err != nil {
-		t.Fatalf("error reading test file: %v", err)
-	}
-
-	compareGraphs(t, buf.Bytes(), want)
+	compareGraphs(t, buf.Bytes(), "compose5.dot")
 }
 
 func TestComposeWithEmptyGraph(t *testing.T) {
@@ -142,12 +124,18 @@ func TestComposeWithEmptyGraph(t *testing.T) {
 	var buf bytes.Buffer
 	ComposeDot(&buf, g, a, c)
 
-	want, err := ioutil.ReadFile(path + "compose4.dot")
-	if err != nil {
-		t.Fatalf("error reading test file: %v", err)
-	}
+	compareGraphs(t, buf.Bytes(), "compose4.dot")
+}
+
+func TestComposeWithStandardGraphAndURL(t *testing.T) {
+	g := baseGraph()
+	a, c := baseAttrsAndConfig()
+	c.LegendURL = "http://example.com"
+
+	var buf bytes.Buffer
+	ComposeDot(&buf, g, a, c)
 
-	compareGraphs(t, buf.Bytes(), want)
+	compareGraphs(t, buf.Bytes(), "compose6.dot")
 }
 
 func baseGraph() *Graph {
@@ -199,13 +187,78 @@ func baseAttrsAndConfig() (*DotAttributes, *DotConfig) {
 	return a, c
 }
 
-func compareGraphs(t *testing.T, got, want []byte) {
+func compareGraphs(t *testing.T, got []byte, wantFile string) {
+	wantFile = filepath.Join("testdata", wantFile)
+	want, err := ioutil.ReadFile(wantFile)
+	if err != nil {
+		t.Fatalf("error reading test file %s: %v", wantFile, err)
+	}
+
 	if string(got) != string(want) {
 		d, err := proftest.Diff(got, want)
 		if err != nil {
 			t.Fatalf("error finding diff: %v", err)
 		}
 		t.Errorf("Compose incorrectly wrote %s", string(d))
+		if *updateFlag {
+			err := ioutil.WriteFile(wantFile, got, 0644)
+			if err != nil {
+				t.Errorf("failed to update the golden file %q: %v", wantFile, err)
+			}
+		}
+	}
+}
+
+func TestNodeletCountCapping(t *testing.T) {
+	labelTags := make(TagMap)
+	for i := 0; i < 10; i++ {
+		name := fmt.Sprintf("tag-%d", i)
+		labelTags[name] = &Tag{
+			Name: name,
+			Flat: 10,
+			Cum:  10,
+		}
+	}
+	numTags := make(TagMap)
+	for i := 0; i < 10; i++ {
+		name := fmt.Sprintf("num-tag-%d", i)
+		numTags[name] = &Tag{
+			Name:  name,
+			Unit:  "mb",
+			Value: 16,
+			Flat:  10,
+			Cum:   10,
+		}
+	}
+	node1 := &Node{
+		Info:        NodeInfo{Name: "node1-with-tags"},
+		Flat:        10,
+		Cum:         10,
+		NumericTags: map[string]TagMap{"": numTags},
+		LabelTags:   labelTags,
+	}
+	node2 := &Node{
+		Info: NodeInfo{Name: "node2"},
+		Flat: 15,
+		Cum:  15,
+	}
+	node3 := &Node{
+		Info: NodeInfo{Name: "node3"},
+		Flat: 15,
+		Cum:  15,
+	}
+	g := &Graph{
+		Nodes: Nodes{
+			node1,
+			node2,
+			node3,
+		},
+	}
+	for n := 1; n <= 3; n++ {
+		input := maxNodelets + n
+		if got, want := len(g.SelectTopNodes(input, true)), n; got != want {
+			t.Errorf("SelectTopNodes(%d): got %d nodes, want %d", input, got, want)
+		}
 	}
 }
 
@@ -240,19 +293,19 @@ func TestTagCollapse(t *testing.T) {
 	}
 
 	tagWant := [][]*Tag{
-		[]*Tag{
+		{
 			makeTag("1B..2GB", "", 0, 2401, 2401),
 		},
-		[]*Tag{
+		{
 			makeTag("2GB", "", 0, 1000, 1000),
 			makeTag("1B..12MB", "", 0, 1401, 1401),
 		},
-		[]*Tag{
+		{
 			makeTag("2GB", "", 0, 1000, 1000),
 			makeTag("12MB", "", 0, 100, 100),
 			makeTag("1B..1MB", "", 0, 1301, 1301),
 		},
-		[]*Tag{
+		{
 			makeTag("2GB", "", 0, 1000, 1000),
 			makeTag("1MB", "", 0, 1000, 1000),
 			makeTag("2B..1kB", "", 0, 201, 201),
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/graph.go b/src/cmd/vendor/github.com/google/pprof/internal/graph/graph.go
index 428e6257c7..cd72bf2ab1 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/graph.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/graph.go
@@ -240,6 +240,8 @@ type Edge struct {
 	Inline bool
 }
 
+// WeightValue returns the weight value for this edge, normalizing if a
+// divisor is available.
 func (e *Edge) WeightValue() int64 {
 	if e.WeightDiv == 0 {
 		return e.Weight
@@ -327,7 +329,7 @@ func newGraph(prof *profile.Profile, o *Options) (*Graph, map[uint64]Nodes) {
 				// Add cum weight to all nodes in stack, avoiding double counting.
 				if _, ok := seenNode[n]; !ok {
 					seenNode[n] = true
-					n.addSample(dw, w, labels, sample.NumLabel, o.FormatTag, false)
+					n.addSample(dw, w, labels, sample.NumLabel, sample.NumUnit, o.FormatTag, false)
 				}
 				// Update edge weights for all edges in stack, avoiding double counting.
 				if _, ok := seenEdge[nodePair{n, parent}]; !ok && parent != nil && n != parent {
@@ -340,7 +342,7 @@ func newGraph(prof *profile.Profile, o *Options) (*Graph, map[uint64]Nodes) {
 		}
 		if parent != nil && !residual {
 			// Add flat weight to leaf node.
-			parent.addSample(dw, w, labels, sample.NumLabel, o.FormatTag, true)
+			parent.addSample(dw, w, labels, sample.NumLabel, sample.NumUnit, o.FormatTag, true)
 		}
 	}
 
@@ -399,7 +401,7 @@ func newTree(prof *profile.Profile, o *Options) (g *Graph) {
 				if n == nil {
 					continue
 				}
-				n.addSample(dw, w, labels, sample.NumLabel, o.FormatTag, false)
+				n.addSample(dw, w, labels, sample.NumLabel, sample.NumUnit, o.FormatTag, false)
 				if parent != nil {
 					parent.AddToEdgeDiv(n, dw, w, false, lidx != len(lines)-1)
 				}
@@ -407,7 +409,7 @@ func newTree(prof *profile.Profile, o *Options) (g *Graph) {
 			}
 		}
 		if parent != nil {
-			parent.addSample(dw, w, labels, sample.NumLabel, o.FormatTag, true)
+			parent.addSample(dw, w, labels, sample.NumLabel, sample.NumUnit, o.FormatTag, true)
 		}
 	}
 
@@ -600,7 +602,7 @@ func (ns Nodes) Sum() (flat int64, cum int64) {
 	return
 }
 
-func (n *Node) addSample(dw, w int64, labels string, numLabel map[string][]int64, format func(int64, string) string, flat bool) {
+func (n *Node) addSample(dw, w int64, labels string, numLabel map[string][]int64, numUnit map[string][]string, format func(int64, string) string, flat bool) {
 	// Update sample value
 	if flat {
 		n.FlatDiv += dw
@@ -631,9 +633,15 @@ func (n *Node) addSample(dw, w int64, labels string, numLabel map[string][]int64
 	if format == nil {
 		format = defaultLabelFormat
 	}
-	for key, nvals := range numLabel {
-		for _, v := range nvals {
-			t := numericTags.findOrAddTag(format(v, key), key, v)
+	for k, nvals := range numLabel {
+		units := numUnit[k]
+		for i, v := range nvals {
+			var t *Tag
+			if len(units) > 0 {
+				t = numericTags.findOrAddTag(format(v, units[i]), units[i], v)
+			} else {
+				t = numericTags.findOrAddTag(format(v, k), k, v)
+			}
 			if flat {
 				t.FlatDiv += dw
 				t.Flat += w
@@ -800,7 +808,11 @@ func (g *Graph) selectTopNodes(maxNodes int, visualMode bool) Nodes {
 			// If generating a visual graph, count tags as nodes. Update
 			// maxNodes to account for them.
 			for i, n := range g.Nodes {
-				if count += countTags(n) + 1; count >= maxNodes {
+				tags := countTags(n)
+				if tags > maxNodelets {
+					tags = maxNodelets
+				}
+				if count += tags + 1; count >= maxNodes {
 					maxNodes = i + 1
 					break
 				}
@@ -832,17 +844,6 @@ func countTags(n *Node) int {
 	return count
 }
 
-// countEdges counts the number of edges below the specified cutoff.
-func countEdges(el EdgeMap, cutoff int64) int {
-	count := 0
-	for _, e := range el {
-		if e.Weight > cutoff {
-			count++
-		}
-	}
-	return count
-}
-
 // RemoveRedundantEdges removes residual edges if the destination can
 // be reached through another path. This is done to simplify the graph
 // while preserving connectivity.
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/graph_test.go b/src/cmd/vendor/github.com/google/pprof/internal/graph/graph_test.go
index c2848f8cf2..5657084cac 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/graph_test.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/graph_test.go
@@ -171,7 +171,7 @@ func createExpectedEdges(parent expectedNode, children ...expectedNode) {
 	}
 }
 
-// createTestCase1 creates a test case that initally looks like:
+// createTestCase1 creates a test case that initially looks like:
 //     0
 //     |(5)
 //     1
@@ -255,7 +255,7 @@ func createTestCase2() trimTreeTestcase {
 	}
 }
 
-// createTestCase3 creates an initally empty graph and expects an empty graph
+// createTestCase3 creates an initially empty graph and expects an empty graph
 // after trimming.
 func createTestCase3() trimTreeTestcase {
 	graph := &Graph{make(Nodes, 0)}
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose1.dot b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose1.dot
index ceed025318..da349a40a8 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose1.dot
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose1.dot
@@ -1,7 +1,7 @@
 digraph "testtitle" {
 node [style=filled fillcolor="#f8f8f8"]
-subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l"] }
-N1 [label="src\n10 (10.00%)\nof 25 (25.00%)" fontsize=22 shape=box tooltip="src (25)" color="#b23c00" fillcolor="#edddd5"]
-N2 [label="dest\n15 (15.00%)\nof 25 (25.00%)" fontsize=24 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
+subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l" tooltip="testtitle"] }
+N1 [label="src\n10 (10.00%)\nof 25 (25.00%)" id="node1" fontsize=22 shape=box tooltip="src (25)" color="#b23c00" fillcolor="#edddd5"]
+N2 [label="dest\n15 (15.00%)\nof 25 (25.00%)" id="node2" fontsize=24 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
 N1 -> N2 [label=" 10" weight=11 color="#b28559" tooltip="src -> dest (10)" labeltooltip="src -> dest (10)"]
 }
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose2.dot b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose2.dot
index ee951fe3b1..0c1a6ebaf1 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose2.dot
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose2.dot
@@ -1,7 +1,7 @@
 digraph "testtitle" {
 node [style=filled fillcolor="#f8f8f8"]
-subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l"] }
-N1 [label="SRC10 (10.00%)\nof 25 (25.00%)" fontsize=24 shape=folder tooltip="src (25)" color="#b23c00" fillcolor="#edddd5" style="bold,filled" peripheries=2 URL="www.google.com" target="_blank"]
-N2 [label="dest\n0 of 25 (25.00%)" fontsize=8 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
+subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l" tooltip="testtitle"] }
+N1 [label="SRC10 (10.00%)\nof 25 (25.00%)" id="node1" fontsize=24 shape=folder tooltip="src (25)" color="#b23c00" fillcolor="#edddd5" style="bold,filled" peripheries=2 URL="www.google.com" target="_blank"]
+N2 [label="dest\n0 of 25 (25.00%)" id="node2" fontsize=8 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
 N1 -> N2 [label=" 10" weight=11 color="#b28559" tooltip="src -> dest (10)" labeltooltip="src -> dest (10)"]
 }
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose3.dot b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose3.dot
index 99a3119b82..1b878b79df 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose3.dot
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose3.dot
@@ -1,11 +1,11 @@
 digraph "testtitle" {
 node [style=filled fillcolor="#f8f8f8"]
-subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l"] }
-N1 [label="src\n10 (10.00%)\nof 25 (25.00%)" fontsize=22 shape=box tooltip="src (25)" color="#b23c00" fillcolor="#edddd5"]
-N1_0 [label = "tag1" fontsize=8 shape=box3d tooltip="10"]
+subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l" tooltip="testtitle"] }
+N1 [label="src\n10 (10.00%)\nof 25 (25.00%)" id="node1" fontsize=22 shape=box tooltip="src (25)" color="#b23c00" fillcolor="#edddd5"]
+N1_0 [label = "tag1" id="N1_0" fontsize=8 shape=box3d tooltip="10"]
 N1 -> N1_0 [label=" 10" weight=100 tooltip="10" labeltooltip="10"]
-NN1_0 [label = "tag2" fontsize=8 shape=box3d tooltip="20"]
+NN1_0 [label = "tag2" id="NN1_0" fontsize=8 shape=box3d tooltip="20"]
 N1 -> NN1_0 [label=" 20" weight=100 tooltip="20" labeltooltip="20"]
-N2 [label="dest\n15 (15.00%)\nof 25 (25.00%)" fontsize=24 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
+N2 [label="dest\n15 (15.00%)\nof 25 (25.00%)" id="node2" fontsize=24 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
 N1 -> N2 [label=" 10" weight=11 color="#b28559" tooltip="src ... dest (10)" labeltooltip="src ... dest (10)" style="dotted" minlen=2]
 }
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose4.dot b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose4.dot
index adc9cc6f68..302da8ce94 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose4.dot
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose4.dot
@@ -1,4 +1,4 @@
 digraph "testtitle" {
 node [style=filled fillcolor="#f8f8f8"]
-subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l"] }
+subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l" tooltip="testtitle"] }
 }
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose5.dot b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose5.dot
index 352975f587..8876e337e6 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose5.dot
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose5.dot
@@ -1,11 +1,11 @@
 digraph "testtitle" {
 node [style=filled fillcolor="#f8f8f8"]
-subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l"] }
-N1 [label="src\n10 (10.00%)\nof 25 (25.00%)" fontsize=22 shape=box tooltip="src (25)" color="#b23c00" fillcolor="#edddd5"]
-N1_0 [label = "tag1" fontsize=8 shape=box3d tooltip="10"]
+subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l" tooltip="testtitle"] }
+N1 [label="src\n10 (10.00%)\nof 25 (25.00%)" id="node1" fontsize=22 shape=box tooltip="src (25)" color="#b23c00" fillcolor="#edddd5"]
+N1_0 [label = "tag1" id="N1_0" fontsize=8 shape=box3d tooltip="10"]
 N1 -> N1_0 [label=" 10" weight=100 tooltip="10" labeltooltip="10"]
-NN1_0_0 [label = "tag2" fontsize=8 shape=box3d tooltip="20"]
+NN1_0_0 [label = "tag2" id="NN1_0_0" fontsize=8 shape=box3d tooltip="20"]
 N1_0 -> NN1_0_0 [label=" 20" weight=100 tooltip="20" labeltooltip="20"]
-N2 [label="dest\n15 (15.00%)\nof 25 (25.00%)" fontsize=24 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
+N2 [label="dest\n15 (15.00%)\nof 25 (25.00%)" id="node2" fontsize=24 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
 N1 -> N2 [label=" 10" weight=11 color="#b28559" tooltip="src -> dest (10)" labeltooltip="src -> dest (10)" minlen=2]
 }
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose6.dot b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose6.dot
new file mode 100644
index 0000000000..cf884394c7
--- /dev/null
+++ b/src/cmd/vendor/github.com/google/pprof/internal/graph/testdata/compose6.dot
@@ -0,0 +1,7 @@
+digraph "testtitle" {
+node [style=filled fillcolor="#f8f8f8"]
+subgraph cluster_L { "label1" [shape=box fontsize=16 label="label1\llabel2\l" URL="http://example.com" target="_blank" tooltip="testtitle"] }
+N1 [label="src\n10 (10.00%)\nof 25 (25.00%)" id="node1" fontsize=22 shape=box tooltip="src (25)" color="#b23c00" fillcolor="#edddd5"]
+N2 [label="dest\n15 (15.00%)\nof 25 (25.00%)" id="node2" fontsize=24 shape=box tooltip="dest (25)" color="#b23c00" fillcolor="#edddd5"]
+N1 -> N2 [label=" 10" weight=11 color="#b28559" tooltip="src -> dest (10)" labeltooltip="src -> dest (10)"]
+}