libgo: update to Go 1.8 release candidate 1

    
    Compiler changes:
      * Change map assignment to use mapassign and assign value directly.
      * Change string iteration to use decoderune, faster for ASCII strings.
      * Change makeslice to take int, and use makeslice64 for larger values.
      * Add new noverflow field to hmap struct used for maps.
    
    Unresolved problems, to be fixed later:
      * Commented out test in go/types/sizes_test.go that doesn't compile.
      * Commented out reflect.TestStructOf test for padding after zero-sized field.
    
    Reviewed-on: https://go-review.googlesource.com/35231

gotools/:
	Updates for Go 1.8rc1.
	* Makefile.am (go_cmd_go_files): Add bug.go.
	(s-zdefaultcc): Write defaultPkgConfig.
	* Makefile.in: Rebuild.

From-SVN: r244456

7 files changed, 767 insertions, 131 deletions

diff --git a/libgo/go/runtime/pprof/internal/protopprof/protomemprofile.go b/libgo/go/runtime/pprof/internal/protopprof/protomemprofile.go
new file mode 100644
index 0000000..c2ab5b5
--- /dev/null
+++ b/libgo/go/runtime/pprof/internal/protopprof/protomemprofile.go
@@ -0,0 +1,83 @@
+// Copyright 2016 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 protopprof
+
+import (
+	"internal/pprof/profile"
+	"math"
+	"runtime"
+	"time"
+)
+
+// EncodeMemProfile converts MemProfileRecords to a Profile.
+func EncodeMemProfile(mr []runtime.MemProfileRecord, rate int64, t time.Time) *profile.Profile {
+	p := &profile.Profile{
+		Period:     rate,
+		PeriodType: &profile.ValueType{Type: "space", Unit: "bytes"},
+		SampleType: []*profile.ValueType{
+			{Type: "alloc_objects", Unit: "count"},
+			{Type: "alloc_space", Unit: "bytes"},
+			{Type: "inuse_objects", Unit: "count"},
+			{Type: "inuse_space", Unit: "bytes"},
+		},
+		TimeNanos: int64(t.UnixNano()),
+	}
+
+	locs := make(map[uintptr]*profile.Location)
+	for _, r := range mr {
+		stack := r.Stack()
+		sloc := make([]*profile.Location, len(stack))
+		for i, addr := range stack {
+			loc := locs[addr]
+			if loc == nil {
+				loc = &profile.Location{
+					ID:      uint64(len(p.Location) + 1),
+					Address: uint64(addr),
+				}
+				locs[addr] = loc
+				p.Location = append(p.Location, loc)
+			}
+			sloc[i] = loc
+		}
+
+		ao, ab := scaleHeapSample(r.AllocObjects, r.AllocBytes, rate)
+		uo, ub := scaleHeapSample(r.InUseObjects(), r.InUseBytes(), rate)
+
+		p.Sample = append(p.Sample, &profile.Sample{
+			Value:    []int64{ao, ab, uo, ub},
+			Location: sloc,
+		})
+	}
+	if runtime.GOOS == "linux" {
+		addMappings(p)
+	}
+	return p
+}
+
+// scaleHeapSample adjusts the data from a heap Sample to
+// account for its probability of appearing in the collected
+// data. heap profiles are a sampling of the memory allocations
+// requests in a program. We estimate the unsampled value by dividing
+// each collected sample by its probability of appearing in the
+// profile. heap profiles rely on a poisson process to determine
+// which samples to collect, based on the desired average collection
+// rate R. The probability of a sample of size S to appear in that
+// profile is 1-exp(-S/R).
+func scaleHeapSample(count, size, rate int64) (int64, int64) {
+	if count == 0 || size == 0 {
+		return 0, 0
+	}
+
+	if rate <= 1 {
+		// if rate==1 all samples were collected so no adjustment is needed.
+		// if rate<1 treat as unknown and skip scaling.
+		return count, size
+	}
+
+	avgSize := float64(size) / float64(count)
+	scale := 1 / (1 - math.Exp(-avgSize/float64(rate)))
+
+	return int64(float64(count) * scale), int64(float64(size) * scale)
+}
diff --git a/libgo/go/runtime/pprof/internal/protopprof/protomemprofile_test.go b/libgo/go/runtime/pprof/internal/protopprof/protomemprofile_test.go
new file mode 100644
index 0000000..a10fe77
--- /dev/null
+++ b/libgo/go/runtime/pprof/internal/protopprof/protomemprofile_test.go
@@ -0,0 +1,104 @@
+// Copyright 2016 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 protopprof
+
+import (
+	"bytes"
+	"internal/pprof/profile"
+	"io/ioutil"
+	"reflect"
+	"runtime"
+	"testing"
+	"time"
+)
+
+// TestSampledHeapAllocProfile tests encoding of a memory profile from
+// runtime.MemProfileRecord data.
+func TestSampledHeapAllocProfile(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip("Test requires a system with /proc/self/maps")
+	}
+
+	// Figure out two addresses from /proc/self/maps.
+	mmap, err := ioutil.ReadFile("/proc/self/maps")
+	if err != nil {
+		t.Fatal("Cannot read /proc/self/maps")
+	}
+	rd := bytes.NewReader(mmap)
+	mprof := &profile.Profile{}
+	if err = mprof.ParseMemoryMap(rd); err != nil {
+		t.Fatalf("Cannot parse /proc/self/maps")
+	}
+	if len(mprof.Mapping) < 2 {
+		// It is possible for a binary to only have 1 executable
+		// region of memory.
+		t.Skipf("need 2 or more mappings, got %v", len(mprof.Mapping))
+	}
+	address1 := mprof.Mapping[0].Start
+	address2 := mprof.Mapping[1].Start
+
+	var buf bytes.Buffer
+
+	rec, rate := testMemRecords(address1, address2)
+	p := EncodeMemProfile(rec, rate, time.Now())
+	if err := p.Write(&buf); err != nil {
+		t.Fatalf("Failed to write profile: %v", err)
+	}
+
+	p, err = profile.Parse(&buf)
+	if err != nil {
+		t.Fatalf("Could not parse Profile profile: %v", err)
+	}
+
+	// Expected PeriodType, SampleType and Sample.
+	expectedPeriodType := &profile.ValueType{Type: "space", Unit: "bytes"}
+	expectedSampleType := []*profile.ValueType{
+		{Type: "alloc_objects", Unit: "count"},
+		{Type: "alloc_space", Unit: "bytes"},
+		{Type: "inuse_objects", Unit: "count"},
+		{Type: "inuse_space", Unit: "bytes"},
+	}
+	// Expected samples, with values unsampled according to the profiling rate.
+	expectedSample := []*profile.Sample{
+		{Value: []int64{2050, 2099200, 1537, 1574400}, Location: []*profile.Location{
+			{ID: 1, Mapping: mprof.Mapping[0], Address: address1},
+			{ID: 2, Mapping: mprof.Mapping[1], Address: address2},
+		}},
+		{Value: []int64{1, 829411, 1, 829411}, Location: []*profile.Location{
+			{ID: 3, Mapping: mprof.Mapping[1], Address: address2 + 1},
+			{ID: 4, Mapping: mprof.Mapping[1], Address: address2 + 2},
+		}},
+		{Value: []int64{1, 829411, 0, 0}, Location: []*profile.Location{
+			{ID: 5, Mapping: mprof.Mapping[0], Address: address1 + 1},
+			{ID: 6, Mapping: mprof.Mapping[0], Address: address1 + 2},
+			{ID: 7, Mapping: mprof.Mapping[1], Address: address2 + 3},
+		}},
+	}
+
+	if p.Period != 512*1024 {
+		t.Fatalf("Sampling periods do not match")
+	}
+	if !reflect.DeepEqual(p.PeriodType, expectedPeriodType) {
+		t.Fatalf("Period types do not match")
+	}
+	if !reflect.DeepEqual(p.SampleType, expectedSampleType) {
+		t.Fatalf("Sample types do not match")
+	}
+	if !reflect.DeepEqual(p.Sample, expectedSample) {
+		t.Fatalf("Samples do not match: Expected: %v, Got:%v", getSampleAsString(expectedSample),
+			getSampleAsString(p.Sample))
+	}
+}
+
+func testMemRecords(a1, a2 uint64) ([]runtime.MemProfileRecord, int64) {
+	addr1, addr2 := uintptr(a1), uintptr(a2)
+	rate := int64(512 * 1024)
+	rec := []runtime.MemProfileRecord{
+		{4096, 1024, 4, 1, [32]uintptr{addr1, addr2}},
+		{512 * 1024, 0, 1, 0, [32]uintptr{addr2 + 1, addr2 + 2}},
+		{512 * 1024, 512 * 1024, 1, 1, [32]uintptr{addr1 + 1, addr1 + 2, addr2 + 3}},
+	}
+	return rec, rate
+}
diff --git a/libgo/go/runtime/pprof/internal/protopprof/protopprof.go b/libgo/go/runtime/pprof/internal/protopprof/protopprof.go
new file mode 100644
index 0000000..5d269c4
--- /dev/null
+++ b/libgo/go/runtime/pprof/internal/protopprof/protopprof.go
@@ -0,0 +1,105 @@
+// Copyright 2016 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 protopprof converts the runtime's raw profile logs
+// to Profile structs containing a representation of the pprof
+// protocol buffer profile format.
+package protopprof
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"time"
+	"unsafe"
+
+	"internal/pprof/profile"
+)
+
+// TranslateCPUProfile parses binary CPU profiling stack trace data
+// generated by runtime.CPUProfile() into a profile struct.
+func TranslateCPUProfile(b []byte, startTime time.Time) (*profile.Profile, error) {
+	const wordSize = unsafe.Sizeof(uintptr(0))
+	const minRawProfile = 5 * wordSize // Need a minimum of 5 words.
+	if uintptr(len(b)) < minRawProfile {
+		return nil, fmt.Errorf("truncated profile")
+	}
+	n := int(uintptr(len(b)) / wordSize)
+	data := ((*[1 << 28]uintptr)(unsafe.Pointer(&b[0])))[:n:n]
+	period := data[3]
+	data = data[5:] // skip header
+
+	// profile initialization taken from pprof tool
+	p := &profile.Profile{
+		Period:     int64(period) * 1000,
+		PeriodType: &profile.ValueType{Type: "cpu", Unit: "nanoseconds"},
+		SampleType: []*profile.ValueType{
+			{Type: "samples", Unit: "count"},
+			{Type: "cpu", Unit: "nanoseconds"},
+		},
+		TimeNanos:     int64(startTime.UnixNano()),
+		DurationNanos: time.Since(startTime).Nanoseconds(),
+	}
+	// Parse CPU samples from the profile.
+	locs := make(map[uint64]*profile.Location)
+	for len(b) > 0 {
+		if len(data) < 2 || uintptr(len(data)) < 2+data[1] {
+			return nil, fmt.Errorf("truncated profile")
+		}
+		count := data[0]
+		nstk := data[1]
+		if uintptr(len(data)) < 2+nstk {
+			return nil, fmt.Errorf("truncated profile")
+		}
+		stk := data[2 : 2+nstk]
+		data = data[2+nstk:]
+
+		if count == 0 && nstk == 1 && stk[0] == 0 {
+			// end of data marker
+			break
+		}
+
+		sloc := make([]*profile.Location, len(stk))
+		for i, addr := range stk {
+			addr := uint64(addr)
+			// Addresses from stack traces point to the next instruction after
+			// each call.  Adjust by -1 to land somewhere on the actual call
+			// (except for the leaf, which is not a call).
+			if i > 0 {
+				addr--
+			}
+			loc := locs[addr]
+			if loc == nil {
+				loc = &profile.Location{
+					ID:      uint64(len(p.Location) + 1),
+					Address: addr,
+				}
+				locs[addr] = loc
+				p.Location = append(p.Location, loc)
+			}
+			sloc[i] = loc
+		}
+		p.Sample = append(p.Sample, &profile.Sample{
+			Value:    []int64{int64(count), int64(count) * int64(p.Period)},
+			Location: sloc,
+		})
+	}
+
+	if runtime.GOOS == "linux" {
+		if err := addMappings(p); err != nil {
+			return nil, err
+		}
+	}
+	return p, nil
+}
+
+func addMappings(p *profile.Profile) error {
+	// Parse memory map from /proc/self/maps
+	f, err := os.Open("/proc/self/maps")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return p.ParseMemoryMap(f)
+}
diff --git a/libgo/go/runtime/pprof/internal/protopprof/protopprof_test.go b/libgo/go/runtime/pprof/internal/protopprof/protopprof_test.go
new file mode 100644
index 0000000..f1937b5
--- /dev/null
+++ b/libgo/go/runtime/pprof/internal/protopprof/protopprof_test.go
@@ -0,0 +1,171 @@
+// Copyright 2016 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 protopprof
+
+import (
+	"bytes"
+	"fmt"
+	"internal/pprof/profile"
+	"io/ioutil"
+	"reflect"
+	"runtime"
+	"testing"
+	"time"
+	"unsafe"
+)
+
+// Helper function to initialize empty cpu profile with sampling period provided.
+func createEmptyProfileWithPeriod(t *testing.T, periodMs uint64) bytes.Buffer {
+	// Mock the sample header produced by cpu profiler. Write a sample
+	// period of 2000 microseconds, followed by no samples.
+	buf := new(bytes.Buffer)
+	// Profile header is as follows:
+	// The first, third and fifth words are 0. The second word is 3.
+	// The fourth word is the period.
+	// EOD marker:
+	// The sixth word -- count is initialized to 0 above.
+	// The code below sets the seventh word -- nstk to 1
+	// The eighth word -- addr is initialized to 0 above.
+	words := []int{0, 3, 0, int(periodMs), 0, 0, 1, 0}
+	n := int(unsafe.Sizeof(0)) * len(words)
+	data := ((*[1 << 29]byte)(unsafe.Pointer(&words[0])))[:n:n]
+	if _, err := buf.Write(data); err != nil {
+		t.Fatalf("createEmptyProfileWithPeriod failed: %v", err)
+	}
+	return *buf
+}
+
+// Helper function to initialize cpu profile with two sample values.
+func createProfileWithTwoSamples(t *testing.T, periodMs uintptr, count1 uintptr, count2 uintptr,
+	address1 uintptr, address2 uintptr) bytes.Buffer {
+	// Mock the sample header produced by cpu profiler. Write a sample
+	// period of 2000 microseconds, followed by no samples.
+	buf := new(bytes.Buffer)
+	words := []uintptr{0, 3, 0, uintptr(periodMs), 0, uintptr(count1), 2,
+		uintptr(address1), uintptr(address1 + 2),
+		uintptr(count2), 2, uintptr(address2), uintptr(address2 + 2),
+		0, 1, 0}
+	for _, n := range words {
+		var err error
+		switch unsafe.Sizeof(int(0)) {
+		case 8:
+			_, err = buf.Write((*[8]byte)(unsafe.Pointer(&n))[:8:8])
+		case 4:
+			_, err = buf.Write((*[4]byte)(unsafe.Pointer(&n))[:4:4])
+		}
+		if err != nil {
+			t.Fatalf("createProfileWithTwoSamples failed: %v", err)
+		}
+	}
+	return *buf
+}
+
+// Tests TranslateCPUProfile parses correct sampling period in an otherwise empty cpu profile.
+func TestTranlateCPUProfileSamplingPeriod(t *testing.T) {
+	// A test server with mock cpu profile data.
+	var buf bytes.Buffer
+
+	startTime := time.Now()
+	b := createEmptyProfileWithPeriod(t, 2000)
+	p, err := TranslateCPUProfile(b.Bytes(), startTime)
+	if err != nil {
+		t.Fatalf("translate failed: %v", err)
+	}
+	if err := p.Write(&buf); err != nil {
+		t.Fatalf("write failed: %v", err)
+	}
+
+	p, err = profile.Parse(&buf)
+	if err != nil {
+		t.Fatalf("Could not parse Profile profile: %v", err)
+	}
+
+	// Expected PeriodType and SampleType.
+	expectedPeriodType := &profile.ValueType{Type: "cpu", Unit: "nanoseconds"}
+	expectedSampleType := []*profile.ValueType{
+		{Type: "samples", Unit: "count"},
+		{Type: "cpu", Unit: "nanoseconds"},
+	}
+	if p.Period != 2000*1000 || !reflect.DeepEqual(p.PeriodType, expectedPeriodType) ||
+		!reflect.DeepEqual(p.SampleType, expectedSampleType) || p.Sample != nil {
+		t.Fatalf("Unexpected Profile fields")
+	}
+}
+
+func getSampleAsString(sample []*profile.Sample) string {
+	var str string
+	for _, x := range sample {
+		for _, y := range x.Location {
+			if y.Mapping != nil {
+				str += fmt.Sprintf("Mapping:%v\n", *y.Mapping)
+			}
+			str += fmt.Sprintf("Location:%v\n", y)
+		}
+		str += fmt.Sprintf("Sample:%v\n", *x)
+	}
+	return str
+}
+
+// Tests TranslateCPUProfile parses a cpu profile with sample values present.
+func TestTranslateCPUProfileWithSamples(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip("test requires a system with /proc/self/maps")
+	}
+	// Figure out two addresses from /proc/self/maps.
+	mmap, err := ioutil.ReadFile("/proc/self/maps")
+	if err != nil {
+		t.Fatal("Cannot read /proc/self/maps")
+	}
+	rd := bytes.NewReader(mmap)
+	mprof := &profile.Profile{}
+	if err = mprof.ParseMemoryMap(rd); err != nil {
+		t.Fatalf("Cannot parse /proc/self/maps")
+	}
+	if len(mprof.Mapping) < 2 {
+		// It is possible for a binary to only have 1 executable
+		// region of memory.
+		t.Skipf("need 2 or more mappings, got %v", len(mprof.Mapping))
+	}
+	address1 := mprof.Mapping[0].Start
+	address2 := mprof.Mapping[1].Start
+	// A test server with mock cpu profile data.
+
+	startTime := time.Now()
+	b := createProfileWithTwoSamples(t, 2000, 20, 40, uintptr(address1), uintptr(address2))
+	p, err := TranslateCPUProfile(b.Bytes(), startTime)
+
+	if err != nil {
+		t.Fatalf("Could not parse Profile profile: %v", err)
+	}
+	// Expected PeriodType, SampleType and Sample.
+	expectedPeriodType := &profile.ValueType{Type: "cpu", Unit: "nanoseconds"}
+	expectedSampleType := []*profile.ValueType{
+		{Type: "samples", Unit: "count"},
+		{Type: "cpu", Unit: "nanoseconds"},
+	}
+	expectedSample := []*profile.Sample{
+		{Value: []int64{20, 20 * 2000 * 1000}, Location: []*profile.Location{
+			{ID: 1, Mapping: mprof.Mapping[0], Address: address1},
+			{ID: 2, Mapping: mprof.Mapping[0], Address: address1 + 1},
+		}},
+		{Value: []int64{40, 40 * 2000 * 1000}, Location: []*profile.Location{
+			{ID: 3, Mapping: mprof.Mapping[1], Address: address2},
+			{ID: 4, Mapping: mprof.Mapping[1], Address: address2 + 1},
+		}},
+	}
+	if p.Period != 2000*1000 {
+		t.Fatalf("Sampling periods do not match")
+	}
+	if !reflect.DeepEqual(p.PeriodType, expectedPeriodType) {
+		t.Fatalf("Period types do not match")
+	}
+	if !reflect.DeepEqual(p.SampleType, expectedSampleType) {
+		t.Fatalf("Sample types do not match")
+	}
+	if !reflect.DeepEqual(p.Sample, expectedSample) {
+		t.Fatalf("Samples do not match: Expected: %v, Got:%v", getSampleAsString(expectedSample),
+			getSampleAsString(p.Sample))
+	}
+}
diff --git a/libgo/go/runtime/pprof/mprof_test.go b/libgo/go/runtime/pprof/mprof_test.go
index 54daefa..079af15 100644
--- a/libgo/go/runtime/pprof/mprof_test.go
+++ b/libgo/go/runtime/pprof/mprof_test.go
@@ -7,6 +7,7 @@ package pprof_test
 import (
 	"bytes"
 	"fmt"
+	"reflect"
 	"regexp"
 	"runtime"
 	. "runtime/pprof"
@@ -42,6 +43,17 @@ func allocatePersistent1K() {
 	}
 }
 
+// Allocate transient memory using reflect.Call.
+
+func allocateReflectTransient() {
+	memSink = make([]byte, 2<<20)
+}
+
+func allocateReflect() {
+	rv := reflect.ValueOf(allocateReflectTransient)
+	rv.Call(nil)
+}
+
 var memoryProfilerRun = 0
 
 func TestMemoryProfiler(t *testing.T) {
@@ -61,6 +73,7 @@ func TestMemoryProfiler(t *testing.T) {
 	allocateTransient1M()
 	allocateTransient2M()
 	allocatePersistent1K()
+	allocateReflect()
 	memSink = nil
 
 	runtime.GC() // materialize stats
@@ -74,21 +87,25 @@ func TestMemoryProfiler(t *testing.T) {
 	tests := []string{
 
 		fmt.Sprintf(`%v: %v \[%v: %v\] @ 0x[0-9,a-f x]+
-#	0x[0-9,a-f]+	pprof_test\.allocatePersistent1K\+0x[0-9,a-f]+	.*/mprof_test\.go:40
-#	0x[0-9,a-f]+	runtime_pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test\.go:63
+#	0x[0-9,a-f]+	pprof_test\.allocatePersistent1K\+0x[0-9,a-f]+	.*/mprof_test\.go:41
+#	0x[0-9,a-f]+	runtime_pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test\.go:75
 `, 32*memoryProfilerRun, 1024*memoryProfilerRun, 32*memoryProfilerRun, 1024*memoryProfilerRun),
 
 		fmt.Sprintf(`0: 0 \[%v: %v\] @ 0x[0-9,a-f x]+
-#	0x[0-9,a-f]+	pprof_test\.allocateTransient1M\+0x[0-9,a-f]+	.*/mprof_test.go:21
-#	0x[0-9,a-f]+	runtime_pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:61
+#	0x[0-9,a-f]+	pprof_test\.allocateTransient1M\+0x[0-9,a-f]+	.*/mprof_test.go:22
+#	0x[0-9,a-f]+	runtime_pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:73
 `, (1<<10)*memoryProfilerRun, (1<<20)*memoryProfilerRun),
 
 		// This should start with "0: 0" but gccgo's imprecise
 		// GC means that sometimes the value is not collected.
 		fmt.Sprintf(`(0|%v): (0|%v) \[%v: %v\] @ 0x[0-9,a-f x]+
-#	0x[0-9,a-f]+	pprof_test\.allocateTransient2M\+0x[0-9,a-f]+	.*/mprof_test.go:27
-#	0x[0-9,a-f]+	runtime_pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:62
+#	0x[0-9,a-f]+	pprof_test\.allocateTransient2M\+0x[0-9,a-f]+	.*/mprof_test.go:28
+#	0x[0-9,a-f]+	runtime_pprof_test\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:74
 `, memoryProfilerRun, (2<<20)*memoryProfilerRun, memoryProfilerRun, (2<<20)*memoryProfilerRun),
+
+		fmt.Sprintf(`0: 0 \[%v: %v\] @( 0x[0-9,a-f]+)+
+#	0x[0-9,a-f]+	pprof_test\.allocateReflectTransient\+0x[0-9,a-f]+	.*/mprof_test.go:49
+`, memoryProfilerRun, (2<<20)*memoryProfilerRun),
 	}
 
 	for _, test := range tests {
diff --git a/libgo/go/runtime/pprof/pprof.go b/libgo/go/runtime/pprof/pprof.go
index 0a58baf..0db1ded 100644
--- a/libgo/go/runtime/pprof/pprof.go
+++ b/libgo/go/runtime/pprof/pprof.go
@@ -73,13 +73,15 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
+	"internal/pprof/profile"
 	"io"
-	"os"
 	"runtime"
+	"runtime/pprof/internal/protopprof"
 	"sort"
 	"strings"
 	"sync"
 	"text/tabwriter"
+	"time"
 )
 
 // BUG(rsc): Profiles are only as good as the kernel support used to generate them.
@@ -99,6 +101,7 @@ import (
 //	heap         - a sampling of all heap allocations
 //	threadcreate - stack traces that led to the creation of new OS threads
 //	block        - stack traces that led to blocking on synchronization primitives
+//	mutex        - stack traces of holders of contended mutexes
 //
 // These predefined profiles maintain themselves and panic on an explicit
 // Add or Remove method call.
@@ -152,6 +155,12 @@ var blockProfile = &Profile{
 	write: writeBlock,
 }
 
+var mutexProfile = &Profile{
+	name:  "mutex",
+	count: countMutex,
+	write: writeMutex,
+}
+
 func lockProfiles() {
 	profiles.mu.Lock()
 	if profiles.m == nil {
@@ -161,6 +170,7 @@ func lockProfiles() {
 			"threadcreate": threadcreateProfile,
 			"heap":         heapProfile,
 			"block":        blockProfile,
+			"mutex":        mutexProfile,
 		}
 	}
 }
@@ -202,21 +212,15 @@ func Profiles() []*Profile {
 	lockProfiles()
 	defer unlockProfiles()
 
-	var all []*Profile
+	all := make([]*Profile, 0, len(profiles.m))
 	for _, p := range profiles.m {
 		all = append(all, p)
 	}
 
-	sort.Sort(byName(all))
+	sort.Slice(all, func(i, j int) bool { return all[i].name < all[j].name })
 	return all
 }
 
-type byName []*Profile
-
-func (x byName) Len() int           { return len(x) }
-func (x byName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
-func (x byName) Less(i, j int) bool { return x[i].name < x[j].name }
-
 // Name returns this profile's name, which can be passed to Lookup to reobtain the profile.
 func (p *Profile) Name() string {
 	return p.name
@@ -299,7 +303,7 @@ func (p *Profile) WriteTo(w io.Writer, debug int) error {
 	}
 
 	// Obtain consistent snapshot under lock; then process without lock.
-	var all [][]uintptr
+	all := make([][]uintptr, 0, len(p.m))
 	p.mu.Lock()
 	for _, stk := range p.m {
 		all = append(all, stk)
@@ -337,17 +341,8 @@ type countProfile interface {
 }
 
 // printCountProfile prints a countProfile at the specified debug level.
+// The profile will be in compressed proto format unless debug is nonzero.
 func printCountProfile(w io.Writer, debug int, name string, p countProfile) error {
-	b := bufio.NewWriter(w)
-	var tw *tabwriter.Writer
-	w = b
-	if debug > 0 {
-		tw = tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
-		w = tw
-	}
-
-	fmt.Fprintf(w, "%s profile: total %d\n", name, p.Len())
-
 	// Build count of each stack.
 	var buf bytes.Buffer
 	key := func(stk []uintptr) string {
@@ -373,17 +368,47 @@ func printCountProfile(w io.Writer, debug int, name string, p countProfile) erro
 
 	sort.Sort(&keysByCount{keys, count})
 
-	for _, k := range keys {
-		fmt.Fprintf(w, "%d %s\n", count[k], k)
-		if debug > 0 {
-			printStackRecord(w, p.Stack(index[k]), false)
+	if debug > 0 {
+		// Print debug profile in legacy format
+		tw := tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
+		fmt.Fprintf(tw, "%s profile: total %d\n", name, p.Len())
+		for _, k := range keys {
+			fmt.Fprintf(tw, "%d %s\n", count[k], k)
+			printStackRecord(tw, p.Stack(index[k]), false)
 		}
+		return tw.Flush()
 	}
 
-	if tw != nil {
-		tw.Flush()
+	// Output profile in protobuf form.
+	prof := &profile.Profile{
+		PeriodType: &profile.ValueType{Type: name, Unit: "count"},
+		Period:     1,
+		Sample:     make([]*profile.Sample, 0, len(keys)),
+		SampleType: []*profile.ValueType{{Type: name, Unit: "count"}},
 	}
-	return b.Flush()
+	locMap := make(map[uintptr]*profile.Location)
+	for _, k := range keys {
+		stk := p.Stack(index[k])
+		c := count[k]
+		locs := make([]*profile.Location, len(stk))
+		for i, addr := range stk {
+			loc := locMap[addr]
+			if loc == nil {
+				loc = &profile.Location{
+					ID:      uint64(len(locMap) + 1),
+					Address: uint64(addr - 1),
+				}
+				prof.Location = append(prof.Location, loc)
+				locMap[addr] = loc
+			}
+			locs[i] = loc
+		}
+		prof.Sample = append(prof.Sample, &profile.Sample{
+			Location: locs,
+			Value:    []int64{int64(c)},
+		})
+	}
+	return prof.Write(w)
 }
 
 // keysByCount sorts keys with higher counts first, breaking ties by key string order.
@@ -449,12 +474,6 @@ func printStackRecord(w io.Writer, stk []uintptr, allFrames bool) {
 
 // Interface to system profiles.
 
-type byInUseBytes []runtime.MemProfileRecord
-
-func (x byInUseBytes) Len() int           { return len(x) }
-func (x byInUseBytes) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
-func (x byInUseBytes) Less(i, j int) bool { return x[i].InUseBytes() > x[j].InUseBytes() }
-
 // WriteHeapProfile is shorthand for Lookup("heap").WriteTo(w, 0).
 // It is preserved for backwards compatibility.
 func WriteHeapProfile(w io.Writer) error {
@@ -490,15 +509,16 @@ func writeHeap(w io.Writer, debug int) error {
 		// Profile grew; try again.
 	}
 
-	sort.Sort(byInUseBytes(p))
+	if debug == 0 {
+		pp := protopprof.EncodeMemProfile(p, int64(runtime.MemProfileRate), time.Now())
+		return pp.Write(w)
+	}
+
+	sort.Slice(p, func(i, j int) bool { return p[i].InUseBytes() > p[j].InUseBytes() })
 
 	b := bufio.NewWriter(w)
-	var tw *tabwriter.Writer
-	w = b
-	if debug > 0 {
-		tw = tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
-		w = tw
-	}
+	tw := tabwriter.NewWriter(b, 1, 8, 1, '\t', 0)
+	w = tw
 
 	var total runtime.MemProfileRecord
 	for i := range p {
@@ -526,9 +546,7 @@ func writeHeap(w io.Writer, debug int) error {
 			fmt.Fprintf(w, " %#x", pc)
 		}
 		fmt.Fprintf(w, "\n")
-		if debug > 0 {
-			printStackRecord(w, r.Stack(), false)
-		}
+		printStackRecord(w, r.Stack(), false)
 	}
 
 	// Print memstats information too.
@@ -554,15 +572,15 @@ func writeHeap(w io.Writer, debug int) error {
 	fmt.Fprintf(w, "# MSpan = %d / %d\n", s.MSpanInuse, s.MSpanSys)
 	fmt.Fprintf(w, "# MCache = %d / %d\n", s.MCacheInuse, s.MCacheSys)
 	fmt.Fprintf(w, "# BuckHashSys = %d\n", s.BuckHashSys)
+	fmt.Fprintf(w, "# GCSys = %d\n", s.GCSys)
+	fmt.Fprintf(w, "# OtherSys = %d\n", s.OtherSys)
 
 	fmt.Fprintf(w, "# NextGC = %d\n", s.NextGC)
 	fmt.Fprintf(w, "# PauseNs = %d\n", s.PauseNs)
 	fmt.Fprintf(w, "# NumGC = %d\n", s.NumGC)
 	fmt.Fprintf(w, "# DebugGC = %v\n", s.DebugGC)
 
-	if tw != nil {
-		tw.Flush()
-	}
+	tw.Flush()
 	return b.Flush()
 }
 
@@ -686,49 +704,29 @@ func StartCPUProfile(w io.Writer) error {
 }
 
 func profileWriter(w io.Writer) {
+	startTime := time.Now()
+	// This will buffer the entire profile into buf and then
+	// translate it into a profile.Profile structure. This will
+	// create two copies of all the data in the profile in memory.
+	// TODO(matloob): Convert each chunk of the proto output and
+	// stream it out instead of converting the entire profile.
+	var buf bytes.Buffer
 	for {
 		data := runtime.CPUProfile()
 		if data == nil {
 			break
 		}
-		w.Write(data)
-	}
-
-	// We are emitting the legacy profiling format, which permits
-	// a memory map following the CPU samples. The memory map is
-	// simply a copy of the GNU/Linux /proc/self/maps file. The
-	// profiler uses the memory map to map PC values in shared
-	// libraries to a shared library in the filesystem, in order
-	// to report the correct function and, if the shared library
-	// has debug info, file/line. This is particularly useful for
-	// PIE (position independent executables) as on ELF systems a
-	// PIE is simply an executable shared library.
-	//
-	// Because the profiling format expects the memory map in
-	// GNU/Linux format, we only do this on GNU/Linux for now. To
-	// add support for profiling PIE on other ELF-based systems,
-	// it may be necessary to map the system-specific mapping
-	// information to the GNU/Linux format. For a reasonably
-	// portable C++ version, see the FillProcSelfMaps function in
-	// https://github.com/gperftools/gperftools/blob/master/src/base/sysinfo.cc
-	//
-	// The code that parses this mapping for the pprof tool is
-	// ParseMemoryMap in cmd/internal/pprof/legacy_profile.go, but
-	// don't change that code, as similar code exists in other
-	// (non-Go) pprof readers. Change this code so that that code works.
-	//
-	// We ignore errors reading or copying the memory map; the
-	// profile is likely usable without it, and we have no good way
-	// to report errors.
-	if runtime.GOOS == "linux" {
-		f, err := os.Open("/proc/self/maps")
-		if err == nil {
-			io.WriteString(w, "\nMAPPED_LIBRARIES:\n")
-			io.Copy(w, f)
-			f.Close()
-		}
+		buf.Write(data)
+	}
+
+	profile, err := protopprof.TranslateCPUProfile(buf.Bytes(), startTime)
+	if err != nil {
+		// The runtime should never produce an invalid or truncated profile.
+		// It drops records that can't fit into its log buffers.
+		panic(fmt.Errorf("could not translate binary profile to proto format: %v", err))
 	}
 
+	profile.Write(w)
 	cpu.done <- true
 }
 
@@ -747,18 +745,18 @@ func StopCPUProfile() {
 	<-cpu.done
 }
 
-type byCycles []runtime.BlockProfileRecord
-
-func (x byCycles) Len() int           { return len(x) }
-func (x byCycles) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
-func (x byCycles) Less(i, j int) bool { return x[i].Cycles > x[j].Cycles }
-
 // countBlock returns the number of records in the blocking profile.
 func countBlock() int {
 	n, _ := runtime.BlockProfile(nil)
 	return n
 }
 
+// countMutex returns the number of records in the mutex profile.
+func countMutex() int {
+	n, _ := runtime.MutexProfile(nil)
+	return n
+}
+
 // writeBlock writes the current blocking profile to w.
 func writeBlock(w io.Writer, debug int) error {
 	var p []runtime.BlockProfileRecord
@@ -772,7 +770,7 @@ func writeBlock(w io.Writer, debug int) error {
 		}
 	}
 
-	sort.Sort(byCycles(p))
+	sort.Slice(p, func(i, j int) bool { return p[i].Cycles > p[j].Cycles })
 
 	b := bufio.NewWriter(w)
 	var tw *tabwriter.Writer
@@ -802,4 +800,49 @@ func writeBlock(w io.Writer, debug int) error {
 	return b.Flush()
 }
 
+// writeMutex writes the current mutex profile to w.
+func writeMutex(w io.Writer, debug int) error {
+	// TODO(pjw): too much common code with writeBlock. FIX!
+	var p []runtime.BlockProfileRecord
+	n, ok := runtime.MutexProfile(nil)
+	for {
+		p = make([]runtime.BlockProfileRecord, n+50)
+		n, ok = runtime.MutexProfile(p)
+		if ok {
+			p = p[:n]
+			break
+		}
+	}
+
+	sort.Slice(p, func(i, j int) bool { return p[i].Cycles > p[j].Cycles })
+
+	b := bufio.NewWriter(w)
+	var tw *tabwriter.Writer
+	w = b
+	if debug > 0 {
+		tw = tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
+		w = tw
+	}
+
+	fmt.Fprintf(w, "--- mutex:\n")
+	fmt.Fprintf(w, "cycles/second=%v\n", runtime_cyclesPerSecond())
+	fmt.Fprintf(w, "sampling period=%d\n", runtime.SetMutexProfileFraction(-1))
+	for i := range p {
+		r := &p[i]
+		fmt.Fprintf(w, "%v %v @", r.Cycles, r.Count)
+		for _, pc := range r.Stack() {
+			fmt.Fprintf(w, " %#x", pc)
+		}
+		fmt.Fprint(w, "\n")
+		if debug > 0 {
+			printStackRecord(w, r.Stack(), true)
+		}
+	}
+
+	if tw != nil {
+		tw.Flush()
+	}
+	return b.Flush()
+}
+
 func runtime_cyclesPerSecond() int64
diff --git a/libgo/go/runtime/pprof/pprof_test.go b/libgo/go/runtime/pprof/pprof_test.go
index 1692d42..6034058 100644
--- a/libgo/go/runtime/pprof/pprof_test.go
+++ b/libgo/go/runtime/pprof/pprof_test.go
@@ -8,8 +8,12 @@ package pprof_test
 
 import (
 	"bytes"
+	"compress/gzip"
 	"fmt"
+	"internal/pprof/profile"
 	"internal/testenv"
+	"io"
+	"io/ioutil"
 	"math/big"
 	"os"
 	"os/exec"
@@ -20,7 +24,6 @@ import (
 	"sync"
 	"testing"
 	"time"
-	"unsafe"
 )
 
 func cpuHogger(f func(), dur time.Duration) {
@@ -87,40 +90,17 @@ func TestCPUProfileMultithreaded(t *testing.T) {
 }
 
 func parseProfile(t *testing.T, valBytes []byte, f func(uintptr, []uintptr)) {
-	// Convert []byte to []uintptr.
-	l := len(valBytes)
-	if i := bytes.Index(valBytes, []byte("\nMAPPED_LIBRARIES:\n")); i >= 0 {
-		l = i
-	}
-	l /= int(unsafe.Sizeof(uintptr(0)))
-	val := *(*[]uintptr)(unsafe.Pointer(&valBytes))
-	val = val[:l]
-
-	// 5 for the header, 3 for the trailer.
-	if l < 5+3 {
-		t.Logf("profile too short: %#x", val)
-		if badOS[runtime.GOOS] {
-			t.Skipf("ignoring failure on %s; see golang.org/issue/13841", runtime.GOOS)
-			return
-		}
-		t.FailNow()
-	}
-
-	hd, val, tl := val[:5], val[5:l-3], val[l-3:]
-	if hd[0] != 0 || hd[1] != 3 || hd[2] != 0 || hd[3] != 1e6/100 || hd[4] != 0 {
-		t.Fatalf("unexpected header %#x", hd)
-	}
-
-	if tl[0] != 0 || tl[1] != 1 || tl[2] != 0 {
-		t.Fatalf("malformed end-of-data marker %#x", tl)
+	p, err := profile.Parse(bytes.NewReader(valBytes))
+	if err != nil {
+		t.Fatal(err)
 	}
-
-	for len(val) > 0 {
-		if len(val) < 2 || val[0] < 1 || val[1] < 1 || uintptr(len(val)) < 2+val[1] {
-			t.Fatalf("malformed profile.  leftover: %#x", val)
+	for _, sample := range p.Sample {
+		count := uintptr(sample.Value[0])
+		stk := make([]uintptr, len(sample.Location))
+		for i := range sample.Location {
+			stk[i] = uintptr(sample.Location[i].Address)
 		}
-		f(val[0], val[2:2+val[1]])
-		val = val[2+val[1]:]
+		f(count, stk)
 	}
 }
 
@@ -225,7 +205,11 @@ func profileOk(t *testing.T, need []string, prof bytes.Buffer, duration time.Dur
 	}
 
 	// Check that we got a reasonable number of samples.
-	if ideal := uintptr(duration * 100 / time.Second); samples == 0 || samples < ideal/4 {
+	// We used to always require at least ideal/4 samples,
+	// but that is too hard to guarantee on a loaded system.
+	// Now we accept 10 or more samples, which we take to be
+	// enough to show that at least some profiling is occurring.
+	if ideal := uintptr(duration * 100 / time.Second); samples == 0 || (samples < ideal/4 && samples < 10) {
 		t.Logf("too few samples; got %d, want at least %d, ideally %d", samples, ideal/4, ideal)
 		ok = false
 	}
@@ -367,8 +351,49 @@ func TestMathBigDivide(t *testing.T) {
 	})
 }
 
+func slurpString(r io.Reader) string {
+	slurp, _ := ioutil.ReadAll(r)
+	return string(slurp)
+}
+
+func getLinuxKernelConfig() string {
+	if f, err := os.Open("/proc/config"); err == nil {
+		defer f.Close()
+		return slurpString(f)
+	}
+	if f, err := os.Open("/proc/config.gz"); err == nil {
+		defer f.Close()
+		r, err := gzip.NewReader(f)
+		if err != nil {
+			return ""
+		}
+		return slurpString(r)
+	}
+	if f, err := os.Open("/boot/config"); err == nil {
+		defer f.Close()
+		return slurpString(f)
+	}
+	uname, _ := exec.Command("uname", "-r").Output()
+	if len(uname) > 0 {
+		if f, err := os.Open("/boot/config-" + strings.TrimSpace(string(uname))); err == nil {
+			defer f.Close()
+			return slurpString(f)
+		}
+	}
+	return ""
+}
+
+func haveLinuxHiresTimers() bool {
+	config := getLinuxKernelConfig()
+	return strings.Contains(config, "CONFIG_HIGH_RES_TIMERS=y")
+}
+
 func TestStackBarrierProfiling(t *testing.T) {
-	if (runtime.GOOS == "linux" && runtime.GOARCH == "arm") || runtime.GOOS == "openbsd" || runtime.GOOS == "solaris" || runtime.GOOS == "dragonfly" || runtime.GOOS == "freebsd" {
+	if (runtime.GOOS == "linux" && runtime.GOARCH == "arm") ||
+		runtime.GOOS == "openbsd" ||
+		runtime.GOOS == "solaris" ||
+		runtime.GOOS == "dragonfly" ||
+		runtime.GOOS == "freebsd" {
 		// This test currently triggers a large number of
 		// usleep(100)s. These kernels/arches have poor
 		// resolution timers, so this gives up a whole
@@ -381,6 +406,12 @@ func TestStackBarrierProfiling(t *testing.T) {
 		return
 	}
 
+	if runtime.GOOS == "linux" && strings.HasPrefix(runtime.GOARCH, "mips") {
+		if !haveLinuxHiresTimers() {
+			t.Skipf("low resolution timers inhibit profiling signals (golang.org/issue/13405, golang.org/issue/17936)")
+		}
+	}
+
 	if !strings.Contains(os.Getenv("GODEBUG"), "gcstackbarrierall=1") {
 		// Re-execute this test with constant GC and stack
 		// barriers at every frame.
@@ -594,6 +625,50 @@ func blockCond() {
 	mu.Unlock()
 }
 
+func TestMutexProfile(t *testing.T) {
+	old := runtime.SetMutexProfileFraction(1)
+	defer runtime.SetMutexProfileFraction(old)
+	if old != 0 {
+		t.Fatalf("need MutexProfileRate 0, got %d", old)
+	}
+
+	blockMutex()
+
+	var w bytes.Buffer
+	Lookup("mutex").WriteTo(&w, 1)
+	prof := w.String()
+
+	if !strings.HasPrefix(prof, "--- mutex:\ncycles/second=") {
+		t.Errorf("Bad profile header:\n%v", prof)
+	}
+	prof = strings.Trim(prof, "\n")
+	lines := strings.Split(prof, "\n")
+	// gccgo adds an extra line in the stack trace, not sure why.
+	if len(lines) < 6 {
+		t.Errorf("expected 6 lines, got %d %q\n%s", len(lines), prof, prof)
+	}
+	if len(lines) < 6 {
+		return
+	}
+	// checking that the line is like "35258904 1 @ 0x48288d 0x47cd28 0x458931"
+	r2 := `^\d+ 1 @(?: 0x[[:xdigit:]]+)+`
+	//r2 := "^[0-9]+ 1 @ 0x[0-9a-f x]+$"
+	if ok, err := regexp.MatchString(r2, lines[3]); err != nil || !ok {
+		t.Errorf("%q didn't match %q", lines[3], r2)
+	}
+	r3 := "^#.*pprof_test.\\$nested.*$"
+	match := false
+	for _, i := range []int{5, 6} {
+		if ok, _ := regexp.MatchString(r3, lines[i]); ok {
+			match = true
+			break
+		}
+	}
+	if !match {
+		t.Errorf("neither %q nor %q matched %q", lines[5], lines[6], r3)
+	}
+}
+
 func func1(c chan int) { <-c }
 func func2(c chan int) { <-c }
 func func3(c chan int) { <-c }
@@ -621,13 +696,31 @@ func TestGoroutineCounts(t *testing.T) {
 	time.Sleep(10 * time.Millisecond) // let goroutines block on channel
 
 	var w bytes.Buffer
-	Lookup("goroutine").WriteTo(&w, 1)
+	goroutineProf := Lookup("goroutine")
+
+	// Check debug profile
+	goroutineProf.WriteTo(&w, 1)
 	prof := w.String()
 
 	if !containsInOrder(prof, "\n50 @ ", "\n40 @", "\n10 @", "\n1 @") {
 		t.Errorf("expected sorted goroutine counts:\n%s", prof)
 	}
 
+	// Check proto profile
+	w.Reset()
+	goroutineProf.WriteTo(&w, 0)
+	p, err := profile.Parse(&w)
+	if err != nil {
+		t.Errorf("error parsing protobuf profile: %v", err)
+	}
+	if err := p.CheckValid(); err != nil {
+		t.Errorf("protobuf profile is invalid: %v", err)
+	}
+	if !containsCounts(p, []int64{50, 40, 10, 1}) {
+		t.Errorf("expected count profile to contain goroutines with counts %v, got %v",
+			[]int64{50, 40, 10, 1}, p)
+	}
+
 	close(c)
 
 	time.Sleep(10 * time.Millisecond) // let goroutines exit
@@ -643,3 +736,23 @@ func containsInOrder(s string, all ...string) bool {
 	}
 	return true
 }
+
+func containsCounts(prof *profile.Profile, counts []int64) bool {
+	m := make(map[int64]int)
+	for _, c := range counts {
+		m[c]++
+	}
+	for _, s := range prof.Sample {
+		// The count is the single value in the sample
+		if len(s.Value) != 1 {
+			return false
+		}
+		m[s.Value[0]]--
+	}
+	for _, n := range m {
+		if n > 0 {
+			return false
+		}
+	}
+	return true
+}