cmd/compile,cmd/preprofile: move logic to shared common package

The processing performed in cmd/preprofile is a simple version of the
same initial processing performed by cmd/compile/internal/pgo. Refactor
this processing into the new IR-independent cmd/internal/pgo package.

Now cmd/preprofile and cmd/compile run the same code for initial
processing of a pprof profile, guaranteeing that they always stay in
sync.

Since it is now trivial, this CL makes one change to the serialization
format: the entries are ordered by weight. This allows us to avoid
sorting ByWeight on deserialization.

Impact on PGO parsing when compiling cmd/compile with PGO:

* Without preprocessing: PGO parsing ~13.7% of CPU time
* With preprocessing (unsorted): ~2.9% of CPU time (sorting ~1.7%)
* With preprocessing (sorted): ~1.3% of CPU time

The remaining 1.3% of CPU time approximately breaks down as:

* ~0.5% parsing the preprocessed profile
* ~0.7% building weighted IR call graph
  * ~0.5% walking function IR to find direct calls
  * ~0.2% performing lookups for indirect calls targets

For #58102.

Change-Id: Iaba425ea30b063ca195fb2f7b29342961c8a64c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/569337
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

9 files changed, 574 insertions, 0 deletions

diff --git a/src/cmd/internal/pgo/deserialize.go b/src/cmd/internal/pgo/deserialize.go
new file mode 100644
index 0000000000..4b075b8daf
--- /dev/null
+++ b/src/cmd/internal/pgo/deserialize.go
@@ -0,0 +1,102 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pgo
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strings"
+	"strconv"
+)
+
+// IsSerialized returns true if r is a serialized Profile.
+//
+// IsSerialized only peeks at r, so seeking back after calling is not
+// necessary.
+func IsSerialized(r *bufio.Reader) (bool, error) {
+	hdr, err := r.Peek(len(serializationHeader))
+	if err == io.EOF {
+		// Empty file.
+		return false, nil
+	} else if err != nil {
+		return false, fmt.Errorf("error reading profile header: %w", err)
+	}
+
+	return string(hdr) == serializationHeader, nil
+}
+
+// FromSerialized parses a profile from serialization output of Profile.WriteTo.
+func FromSerialized(r io.Reader) (*Profile, error) {
+	d := emptyProfile()
+
+	scanner := bufio.NewScanner(r)
+	scanner.Split(bufio.ScanLines)
+
+	if !scanner.Scan() {
+		if err := scanner.Err(); err != nil {
+			return nil, fmt.Errorf("error reading preprocessed profile: %w", err)
+		}
+		return nil, fmt.Errorf("preprocessed profile missing header")
+	}
+	if gotHdr := scanner.Text() + "\n"; gotHdr != serializationHeader {
+		return nil, fmt.Errorf("preprocessed profile malformed header; got %q want %q", gotHdr, serializationHeader)
+	}
+
+	for scanner.Scan() {
+		readStr := scanner.Text()
+
+		callerName := readStr
+
+		if !scanner.Scan() {
+			if err := scanner.Err(); err != nil {
+				return nil, fmt.Errorf("error reading preprocessed profile: %w", err)
+			}
+			return nil, fmt.Errorf("preprocessed profile entry missing callee")
+		}
+		calleeName := scanner.Text()
+
+		if !scanner.Scan() {
+			if err := scanner.Err(); err != nil {
+				return nil, fmt.Errorf("error reading preprocessed profile: %w", err)
+			}
+			return nil, fmt.Errorf("preprocessed profile entry missing weight")
+		}
+		readStr = scanner.Text()
+
+		split := strings.Split(readStr, " ")
+
+		if len(split) != 2 {
+			return nil, fmt.Errorf("preprocessed profile entry got %v want 2 fields", split)
+		}
+
+		co, err := strconv.Atoi(split[0])
+		if err != nil {
+			return nil, fmt.Errorf("preprocessed profile error processing call line: %w", err)
+		}
+
+		edge := NamedCallEdge{
+			CallerName:     callerName,
+			CalleeName:     calleeName,
+			CallSiteOffset: co,
+		}
+
+		weight, err := strconv.ParseInt(split[1], 10, 64)
+		if err != nil {
+			return nil, fmt.Errorf("preprocessed profile error processing call weight: %w", err)
+		}
+
+		if _, ok := d.NamedEdgeMap.Weight[edge]; ok {
+			return nil, fmt.Errorf("preprocessed profile contains duplicate edge %+v", edge)
+		}
+
+		d.NamedEdgeMap.ByWeight = append(d.NamedEdgeMap.ByWeight, edge) // N.B. serialization is ordered.
+		d.NamedEdgeMap.Weight[edge] += weight
+		d.TotalWeight += weight
+	}
+
+	return d, nil
+
+}
diff --git a/src/cmd/internal/pgo/pgo.go b/src/cmd/internal/pgo/pgo.go
new file mode 100644
index 0000000000..1d2cb880f7
--- /dev/null
+++ b/src/cmd/internal/pgo/pgo.go
@@ -0,0 +1,55 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package pgo contains the compiler-agnostic portions of PGO profile handling.
+// Notably, parsing pprof profiles and serializing/deserializing from a custom
+// intermediate representation.
+package pgo
+
+// Profile contains the processed data from the PGO profile.
+type Profile struct {
+	// TotalWeight is the aggregated edge weights across the profile. This
+	// helps us determine the percentage threshold for hot/cold
+	// partitioning.
+	TotalWeight int64
+
+	// NamedEdgeMap contains all unique call edges in the profile and their
+	// edge weight.
+	NamedEdgeMap NamedEdgeMap
+}
+
+// NamedCallEdge identifies a call edge by linker symbol names and call site
+// offset.
+type NamedCallEdge struct {
+	CallerName     string
+	CalleeName     string
+	CallSiteOffset int // Line offset from function start line.
+}
+
+// NamedEdgeMap contains all unique call edges in the profile and their
+// edge weight.
+type NamedEdgeMap struct {
+	Weight map[NamedCallEdge]int64
+
+	// ByWeight lists all keys in Weight, sorted by edge weight from
+	// highest to lowest.
+	ByWeight []NamedCallEdge
+}
+
+func emptyProfile() *Profile {
+	// Initialize empty maps/slices for easier use without a requiring a
+	// nil check.
+	return &Profile{
+		NamedEdgeMap: NamedEdgeMap{
+			ByWeight: make([]NamedCallEdge, 0),
+			Weight:   make(map[NamedCallEdge]int64),
+		},
+	}
+}
+
+// WeightInPercentage converts profile weights to a percentage.
+func WeightInPercentage(value int64, total int64) float64 {
+	return (float64(value) / float64(total)) * 100
+}
+
diff --git a/src/cmd/internal/pgo/pprof.go b/src/cmd/internal/pgo/pprof.go
new file mode 100644
index 0000000000..5e61a11141
--- /dev/null
+++ b/src/cmd/internal/pgo/pprof.go
@@ -0,0 +1,140 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package pgo contains the compiler-agnostic portions of PGO profile handling.
+// Notably, parsing pprof profiles and serializing/deserializing from a custom
+// intermediate representation.
+package pgo
+
+import (
+	"errors"
+	"fmt"
+	"internal/profile"
+	"io"
+	"sort"
+)
+
+// FromPProf parses Profile from a pprof profile.
+func FromPProf(r io.Reader) (*Profile, error) {
+	p, err := profile.Parse(r)
+	if errors.Is(err, profile.ErrNoData) {
+		// Treat a completely empty file the same as a profile with no
+		// samples: nothing to do.
+		return emptyProfile(), nil
+	} else if err != nil {
+		return nil, fmt.Errorf("error parsing profile: %w", err)
+	}
+
+	if len(p.Sample) == 0 {
+		// We accept empty profiles, but there is nothing to do.
+		return emptyProfile(), nil
+	}
+
+	valueIndex := -1
+	for i, s := range p.SampleType {
+		// Samples count is the raw data collected, and CPU nanoseconds is just
+		// a scaled version of it, so either one we can find is fine.
+		if (s.Type == "samples" && s.Unit == "count") ||
+			(s.Type == "cpu" && s.Unit == "nanoseconds") {
+			valueIndex = i
+			break
+		}
+	}
+
+	if valueIndex == -1 {
+		return nil, fmt.Errorf(`profile does not contain a sample index with value/type "samples/count" or cpu/nanoseconds"`)
+	}
+
+	g := profile.NewGraph(p, &profile.Options{
+		SampleValue: func(v []int64) int64 { return v[valueIndex] },
+	})
+
+	namedEdgeMap, totalWeight, err := createNamedEdgeMap(g)
+	if err != nil {
+		return nil, err
+	}
+
+	if totalWeight == 0 {
+		return emptyProfile(), nil // accept but ignore profile with no samples.
+	}
+
+	return &Profile{
+		TotalWeight:  totalWeight,
+		NamedEdgeMap: namedEdgeMap,
+	}, nil
+}
+
+// createNamedEdgeMap builds a map of callsite-callee edge weights from the
+// profile-graph.
+//
+// Caller should ignore the profile if totalWeight == 0.
+func createNamedEdgeMap(g *profile.Graph) (edgeMap NamedEdgeMap, totalWeight int64, err error) {
+	seenStartLine := false
+
+	// Process graph and build various node and edge maps which will
+	// be consumed by AST walk.
+	weight := make(map[NamedCallEdge]int64)
+	for _, n := range g.Nodes {
+		seenStartLine = seenStartLine || n.Info.StartLine != 0
+
+		canonicalName := n.Info.Name
+		// Create the key to the nodeMapKey.
+		namedEdge := NamedCallEdge{
+			CallerName:     canonicalName,
+			CallSiteOffset: n.Info.Lineno - n.Info.StartLine,
+		}
+
+		for _, e := range n.Out {
+			totalWeight += e.WeightValue()
+			namedEdge.CalleeName = e.Dest.Info.Name
+			// Create new entry or increment existing entry.
+			weight[namedEdge] += e.WeightValue()
+		}
+	}
+
+	if !seenStartLine {
+		// TODO(prattmic): If Function.start_line is missing we could
+		// fall back to using absolute line numbers, which is better
+		// than nothing.
+		return NamedEdgeMap{}, 0, fmt.Errorf("profile missing Function.start_line data (Go version of profiled application too old? Go 1.20+ automatically adds this to profiles)")
+	}
+	return postProcessNamedEdgeMap(weight, totalWeight)
+}
+
+func sortByWeight(edges []NamedCallEdge, weight map[NamedCallEdge]int64) {
+	sort.Slice(edges, func(i, j int) bool {
+		ei, ej := edges[i], edges[j]
+		if wi, wj := weight[ei], weight[ej]; wi != wj {
+			return wi > wj // want larger weight first
+		}
+		// same weight, order by name/line number
+		if ei.CallerName != ej.CallerName {
+			return ei.CallerName < ej.CallerName
+		}
+		if ei.CalleeName != ej.CalleeName {
+			return ei.CalleeName < ej.CalleeName
+		}
+		return ei.CallSiteOffset < ej.CallSiteOffset
+	})
+}
+
+func postProcessNamedEdgeMap(weight map[NamedCallEdge]int64, weightVal int64) (edgeMap NamedEdgeMap, totalWeight int64, err error) {
+	if weightVal == 0 {
+		return NamedEdgeMap{}, 0, nil // accept but ignore profile with no samples.
+	}
+	byWeight := make([]NamedCallEdge, 0, len(weight))
+	for namedEdge := range weight {
+		byWeight = append(byWeight, namedEdge)
+	}
+	sortByWeight(byWeight, weight)
+
+	edgeMap = NamedEdgeMap{
+		Weight:   weight,
+		ByWeight: byWeight,
+	}
+
+	totalWeight = weightVal
+
+	return edgeMap, totalWeight, nil
+}
diff --git a/src/cmd/internal/pgo/serialize.go b/src/cmd/internal/pgo/serialize.go
new file mode 100644
index 0000000000..caf67ce485
--- /dev/null
+++ b/src/cmd/internal/pgo/serialize.go
@@ -0,0 +1,79 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pgo
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+)
+
+// Serialization of a Profile allows go tool preprofile to construct the edge
+// map only once (rather than once per compile process). The compiler processes
+// then parse the pre-processed data directly from the serialized format.
+//
+// The format of the serialized output is as follows.
+//
+//      GO PREPROFILE V1
+//      caller_name
+//      callee_name
+//      "call site offset" "call edge weight"
+//      ...
+//      caller_name
+//      callee_name
+//      "call site offset" "call edge weight"
+//
+// Entries are sorted by "call edge weight", from highest to lowest.
+
+const serializationHeader = "GO PREPROFILE V1\n"
+
+// WriteTo writes a serialized representation of Profile to w.
+//
+// FromSerialized can parse the format back to Profile.
+//
+// WriteTo implements io.WriterTo.Write.
+func (d *Profile) WriteTo(w io.Writer) (int64, error) {
+	bw := bufio.NewWriter(w)
+
+	var written int64
+
+	// Header
+	n, err := bw.WriteString(serializationHeader)
+	written += int64(n)
+	if err != nil {
+		return written, err
+	}
+
+	for _, edge := range d.NamedEdgeMap.ByWeight {
+		weight := d.NamedEdgeMap.Weight[edge]
+
+		n, err = fmt.Fprintln(bw, edge.CallerName)
+		written += int64(n)
+		if err != nil {
+			return written, err
+		}
+
+		n, err = fmt.Fprintln(bw, edge.CalleeName)
+		written += int64(n)
+		if err != nil {
+			return written, err
+		}
+
+		n, err = fmt.Fprintf(bw, "%d %d\n", edge.CallSiteOffset, weight)
+		written += int64(n)
+		if err != nil {
+			return written, err
+		}
+	}
+
+	if err := bw.Flush(); err != nil {
+		return written, err
+	}
+
+	// No need to serialize TotalWeight, it can be trivially recomputed
+	// during parsing.
+
+	return written, nil
+}
diff --git a/src/cmd/internal/pgo/serialize_test.go b/src/cmd/internal/pgo/serialize_test.go
new file mode 100644
index 0000000000..b24163d1e2
--- /dev/null
+++ b/src/cmd/internal/pgo/serialize_test.go
@@ -0,0 +1,190 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pgo
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// equal returns an error if got and want are not equal.
+func equal(got, want *Profile) error {
+	if got.TotalWeight != want.TotalWeight {
+		return fmt.Errorf("got.TotalWeight %d != want.TotalWeight %d", got.TotalWeight, want.TotalWeight)
+	}
+	if !reflect.DeepEqual(got.NamedEdgeMap.ByWeight, want.NamedEdgeMap.ByWeight) {
+		return fmt.Errorf("got.NamedEdgeMap.ByWeight != want.NamedEdgeMap.ByWeight\ngot = %+v\nwant = %+v", got.NamedEdgeMap.ByWeight, want.NamedEdgeMap.ByWeight)
+	}
+	if !reflect.DeepEqual(got.NamedEdgeMap.Weight, want.NamedEdgeMap.Weight) {
+		return fmt.Errorf("got.NamedEdgeMap.Weight != want.NamedEdgeMap.Weight\ngot = %+v\nwant = %+v", got.NamedEdgeMap.Weight, want.NamedEdgeMap.Weight)
+	}
+
+	return nil
+}
+
+func testRoundTrip(t *testing.T, d *Profile) []byte {
+	var buf bytes.Buffer
+	n, err := d.WriteTo(&buf)
+	if err != nil {
+		t.Fatalf("WriteTo got err %v want nil", err)
+	}
+	if n != int64(buf.Len()) {
+		t.Errorf("WriteTo got n %d want %d", n, int64(buf.Len()))
+	}
+
+	b := buf.Bytes()
+
+	got, err := FromSerialized(&buf)
+	if err != nil {
+		t.Fatalf("processSerialized got err %v want nil", err)
+	}
+	if err := equal(got, d); err != nil {
+		t.Errorf("processSerialized output does not match input: %v", err)
+	}
+
+	return b
+}
+
+func TestEmpty(t *testing.T) {
+	d := emptyProfile()
+	b := testRoundTrip(t, d)
+
+	// Contents should consist of only a header.
+	if string(b) != serializationHeader {
+		t.Errorf("WriteTo got %q want %q", string(b), serializationHeader)
+	}
+}
+
+func TestRoundTrip(t *testing.T) {
+	d := &Profile{
+		TotalWeight: 3,
+		NamedEdgeMap: NamedEdgeMap{
+			ByWeight: []NamedCallEdge{
+				{
+					CallerName: "a",
+					CalleeName: "b",
+					CallSiteOffset: 14,
+				},
+				{
+					CallerName: "c",
+					CalleeName: "d",
+					CallSiteOffset: 15,
+				},
+			},
+			Weight: map[NamedCallEdge]int64{
+				{
+					CallerName: "a",
+					CalleeName: "b",
+					CallSiteOffset: 14,
+				}: 2,
+				{
+					CallerName: "c",
+					CalleeName: "d",
+					CallSiteOffset: 15,
+				}: 1,
+			},
+		},
+	}
+
+	testRoundTrip(t, d)
+}
+
+func constructFuzzProfile(t *testing.T, b []byte) *Profile {
+	// The fuzzer can't construct an arbitrary structure, so instead we
+	// consume bytes from b to act as our edge data.
+	r := bytes.NewReader(b)
+	consumeString := func() (string, bool) {
+		// First byte: how many bytes to read for this string? We only
+		// use a byte to avoid making humongous strings.
+		length, err := r.ReadByte()
+		if err != nil {
+			return "", false
+		}
+		if length == 0 {
+			return "", false
+		}
+
+		b := make([]byte, length)
+		_, err = r.Read(b)
+		if err != nil {
+			return "", false
+		}
+
+		return string(b), true
+	}
+	consumeInt64 := func() (int64, bool) {
+		b := make([]byte, 8)
+		_, err := r.Read(b)
+		if err != nil {
+			return 0, false
+		}
+
+		return int64(binary.LittleEndian.Uint64(b)), true
+	}
+
+	d := emptyProfile()
+
+	for {
+		caller, ok := consumeString()
+		if !ok {
+			break
+		}
+		if strings.ContainsAny(caller, " \r\n") {
+			t.Skip("caller contains space or newline")
+		}
+
+		callee, ok := consumeString()
+		if !ok {
+			break
+		}
+		if strings.ContainsAny(callee, " \r\n") {
+			t.Skip("callee contains space or newline")
+		}
+
+		line, ok := consumeInt64()
+		if !ok {
+			break
+		}
+		weight, ok := consumeInt64()
+		if !ok {
+			break
+		}
+
+		edge := NamedCallEdge{
+			CallerName: caller,
+			CalleeName: callee,
+			CallSiteOffset: int(line),
+		}
+
+		if _, ok := d.NamedEdgeMap.Weight[edge]; ok {
+			t.Skip("duplicate edge")
+		}
+
+		d.NamedEdgeMap.Weight[edge] = weight
+		d.TotalWeight += weight
+	}
+
+	byWeight := make([]NamedCallEdge, 0, len(d.NamedEdgeMap.Weight))
+	for namedEdge := range d.NamedEdgeMap.Weight {
+		byWeight = append(byWeight, namedEdge)
+	}
+	sortByWeight(byWeight, d.NamedEdgeMap.Weight)
+	d.NamedEdgeMap.ByWeight = byWeight
+
+	return d
+}
+
+func FuzzRoundTrip(f *testing.F) {
+	f.Add([]byte("")) // empty profile
+
+	f.Fuzz(func(t *testing.T, b []byte) {
+		d := constructFuzzProfile(t, b)
+		testRoundTrip(t, d)
+	})
+}
diff --git a/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/12fcf136fcb7463c b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/12fcf136fcb7463c
new file mode 100644
index 0000000000..31e3552bdc
--- /dev/null
+++ b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/12fcf136fcb7463c
@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd00000000\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd\xfd0")
diff --git a/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/2055d314024c8d6c b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/2055d314024c8d6c
new file mode 100644
index 0000000000..b44370f012
--- /dev/null
+++ b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/2055d314024c8d6c
@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("\x00\x040000000000000")
diff --git a/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/b615162315f7b72c b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/b615162315f7b72c
new file mode 100644
index 0000000000..094fc10fd6
--- /dev/null
+++ b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/b615162315f7b72c
@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("\b00000000\x01\n000000000")
diff --git a/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/fdc60117b431bbae b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/fdc60117b431bbae
new file mode 100644
index 0000000000..4f9af7b90a
--- /dev/null
+++ b/src/cmd/internal/pgo/testdata/fuzz/FuzzRoundTrip/fdc60117b431bbae
@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("\x010\x01\r000000000")