[dev.fuzz] all: merge master into dev.fuzz

Change-Id: I5d8c8329ccc9d747bd81ade6b1cb7cb8ae2e94b2

22 files changed, 2096 insertions, 657 deletions

diff --git a/src/cmd/vendor/github.com/google/pprof/driver/driver.go b/src/cmd/vendor/github.com/google/pprof/driver/driver.go
index 9bcbc8295a..e65bc2f417 100644
--- a/src/cmd/vendor/github.com/google/pprof/driver/driver.go
+++ b/src/cmd/vendor/github.com/google/pprof/driver/driver.go
@@ -142,7 +142,7 @@ type ObjTool interface {
 
 	// Disasm disassembles the named object file, starting at
 	// the start address and stopping at (before) the end address.
-	Disasm(file string, start, end uint64) ([]Inst, error)
+	Disasm(file string, start, end uint64, intelSyntax bool) ([]Inst, error)
 }
 
 // An Inst is a single instruction in an assembly listing.
@@ -269,8 +269,8 @@ func (f *internalObjFile) Symbols(r *regexp.Regexp, addr uint64) ([]*plugin.Sym,
 	return pluginSyms, nil
 }
 
-func (o *internalObjTool) Disasm(file string, start, end uint64) ([]plugin.Inst, error) {
-	insts, err := o.ObjTool.Disasm(file, start, end)
+func (o *internalObjTool) Disasm(file string, start, end uint64, intelSyntax bool) ([]plugin.Inst, error) {
+	insts, err := o.ObjTool.Disasm(file, start, end, intelSyntax)
 	if err != nil {
 		return nil, err
 	}
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/binutils/binutils.go b/src/cmd/vendor/github.com/google/pprof/internal/binutils/binutils.go
index 967726d1fa..4b67cc4ab0 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/binutils/binutils.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/binutils/binutils.go
@@ -19,6 +19,7 @@ import (
 	"debug/elf"
 	"debug/macho"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -26,6 +27,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strconv"
 	"strings"
 	"sync"
 
@@ -39,6 +41,8 @@ type Binutils struct {
 	rep *binrep
 }
 
+var objdumpLLVMVerRE = regexp.MustCompile(`LLVM version (?:(\d*)\.(\d*)\.(\d*)|.*(trunk).*)`)
+
 // binrep is an immutable representation for Binutils.  It is atomically
 // replaced on every mutation to provide thread-safe access.
 type binrep struct {
@@ -51,6 +55,7 @@ type binrep struct {
 	nmFound             bool
 	objdump             string
 	objdumpFound        bool
+	isLLVMObjdump       bool
 
 	// if fast, perform symbolization using nm (symbol names only),
 	// instead of file-line detail from the slower addr2line.
@@ -132,15 +137,103 @@ func initTools(b *binrep, config string) {
 	}
 
 	defaultPath := paths[""]
-	b.llvmSymbolizer, b.llvmSymbolizerFound = findExe("llvm-symbolizer", append(paths["llvm-symbolizer"], defaultPath...))
-	b.addr2line, b.addr2lineFound = findExe("addr2line", append(paths["addr2line"], defaultPath...))
-	if !b.addr2lineFound {
-		// On MacOS, brew installs addr2line under gaddr2line name, so search for
-		// that if the tool is not found by its default name.
-		b.addr2line, b.addr2lineFound = findExe("gaddr2line", append(paths["addr2line"], defaultPath...))
+	b.llvmSymbolizer, b.llvmSymbolizerFound = chooseExe([]string{"llvm-symbolizer"}, []string{}, append(paths["llvm-symbolizer"], defaultPath...))
+	b.addr2line, b.addr2lineFound = chooseExe([]string{"addr2line"}, []string{"gaddr2line"}, append(paths["addr2line"], defaultPath...))
+	// The "-n" option is supported by LLVM since 2011. The output of llvm-nm
+	// and GNU nm with "-n" option is interchangeable for our purposes, so we do
+	// not need to differrentiate them.
+	b.nm, b.nmFound = chooseExe([]string{"llvm-nm", "nm"}, []string{"gnm"}, append(paths["nm"], defaultPath...))
+	b.objdump, b.objdumpFound, b.isLLVMObjdump = findObjdump(append(paths["objdump"], defaultPath...))
+}
+
+// findObjdump finds and returns path to preferred objdump binary.
+// Order of preference is: llvm-objdump, objdump.
+// On MacOS only, also looks for gobjdump with least preference.
+// Accepts a list of paths and returns:
+// a string with path to the preferred objdump binary if found,
+// or an empty string if not found;
+// a boolean if any acceptable objdump was found;
+// a boolean indicating if it is an LLVM objdump.
+func findObjdump(paths []string) (string, bool, bool) {
+	objdumpNames := []string{"llvm-objdump", "objdump"}
+	if runtime.GOOS == "darwin" {
+		objdumpNames = append(objdumpNames, "gobjdump")
+	}
+
+	for _, objdumpName := range objdumpNames {
+		if objdump, objdumpFound := findExe(objdumpName, paths); objdumpFound {
+			cmdOut, err := exec.Command(objdump, "--version").Output()
+			if err != nil {
+				continue
+			}
+			if isLLVMObjdump(string(cmdOut)) {
+				return objdump, true, true
+			}
+			if isBuObjdump(string(cmdOut)) {
+				return objdump, true, false
+			}
+		}
+	}
+	return "", false, false
+}
+
+// chooseExe finds and returns path to preferred binary. names is a list of
+// names to search on both Linux and OSX. osxNames is a list of names specific
+// to OSX. names always has a higher priority than osxNames. The order of
+// the name within each list decides its priority (e.g. the first name has a
+// higher priority than the second name in the list).
+//
+// It returns a string with path to the binary and a boolean indicating if any
+// acceptable binary was found.
+func chooseExe(names, osxNames []string, paths []string) (string, bool) {
+	if runtime.GOOS == "darwin" {
+		names = append(names, osxNames...)
+	}
+	for _, name := range names {
+		if binary, found := findExe(name, paths); found {
+			return binary, true
+		}
+	}
+	return "", false
+}
+
+// isLLVMObjdump accepts a string with path to an objdump binary,
+// and returns a boolean indicating if the given binary is an LLVM
+// objdump binary of an acceptable version.
+func isLLVMObjdump(output string) bool {
+	fields := objdumpLLVMVerRE.FindStringSubmatch(output)
+	if len(fields) != 5 {
+		return false
+	}
+	if fields[4] == "trunk" {
+		return true
+	}
+	verMajor, err := strconv.Atoi(fields[1])
+	if err != nil {
+		return false
+	}
+	verPatch, err := strconv.Atoi(fields[3])
+	if err != nil {
+		return false
+	}
+	if runtime.GOOS == "linux" && verMajor >= 8 {
+		// Ensure LLVM objdump is at least version 8.0 on Linux.
+		// Some flags, like --demangle, and double dashes for options are
+		// not supported by previous versions.
+		return true
 	}
-	b.nm, b.nmFound = findExe("nm", append(paths["nm"], defaultPath...))
-	b.objdump, b.objdumpFound = findExe("objdump", append(paths["objdump"], defaultPath...))
+	if runtime.GOOS == "darwin" {
+		// Ensure LLVM objdump is at least version 10.0.1 on MacOS.
+		return verMajor > 10 || (verMajor == 10 && verPatch >= 1)
+	}
+	return false
+}
+
+// isBuObjdump accepts a string with path to an objdump binary,
+// and returns a boolean indicating if the given binary is a GNU
+// binutils objdump binary. No version check is performed.
+func isBuObjdump(output string) bool {
+	return strings.Contains(output, "GNU objdump")
 }
 
 // findExe looks for an executable command on a set of paths.
@@ -157,12 +250,25 @@ func findExe(cmd string, paths []string) (string, bool) {
 
 // Disasm returns the assembly instructions for the specified address range
 // of a binary.
-func (bu *Binutils) Disasm(file string, start, end uint64) ([]plugin.Inst, error) {
+func (bu *Binutils) Disasm(file string, start, end uint64, intelSyntax bool) ([]plugin.Inst, error) {
 	b := bu.get()
-	cmd := exec.Command(b.objdump, "-d", "-C", "--no-show-raw-insn", "-l",
-		fmt.Sprintf("--start-address=%#x", start),
-		fmt.Sprintf("--stop-address=%#x", end),
-		file)
+	if !b.objdumpFound {
+		return nil, errors.New("cannot disasm: no objdump tool available")
+	}
+	args := []string{"--disassemble-all", "--demangle", "--no-show-raw-insn",
+		"--line-numbers", fmt.Sprintf("--start-address=%#x", start),
+		fmt.Sprintf("--stop-address=%#x", end)}
+
+	if intelSyntax {
+		if b.isLLVMObjdump {
+			args = append(args, "--x86-asm-syntax=intel")
+		} else {
+			args = append(args, "-M", "intel")
+		}
+	}
+
+	args = append(args, file)
+	cmd := exec.Command(b.objdump, args...)
 	out, err := cmd.Output()
 	if err != nil {
 		return nil, fmt.Errorf("%v: %v", cmd.Args, err)
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/binutils/disasm.go b/src/cmd/vendor/github.com/google/pprof/internal/binutils/disasm.go
index 28c89aa163..d0be614bdc 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/binutils/disasm.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/binutils/disasm.go
@@ -25,10 +25,11 @@ import (
 )
 
 var (
-	nmOutputRE            = regexp.MustCompile(`^\s*([[:xdigit:]]+)\s+(.)\s+(.*)`)
-	objdumpAsmOutputRE    = regexp.MustCompile(`^\s*([[:xdigit:]]+):\s+(.*)`)
-	objdumpOutputFileLine = regexp.MustCompile(`^(.*):([0-9]+)`)
-	objdumpOutputFunction = regexp.MustCompile(`^(\S.*)\(\):`)
+	nmOutputRE                = regexp.MustCompile(`^\s*([[:xdigit:]]+)\s+(.)\s+(.*)`)
+	objdumpAsmOutputRE        = regexp.MustCompile(`^\s*([[:xdigit:]]+):\s+(.*)`)
+	objdumpOutputFileLine     = regexp.MustCompile(`^;?\s?(.*):([0-9]+)`)
+	objdumpOutputFunction     = regexp.MustCompile(`^;?\s?(\S.*)\(\):`)
+	objdumpOutputFunctionLLVM = regexp.MustCompile(`^([[:xdigit:]]+)?\s?(.*):`)
 )
 
 func findSymbols(syms []byte, file string, r *regexp.Regexp, address uint64) ([]*plugin.Sym, error) {
@@ -143,6 +144,11 @@ func disassemble(asm []byte) ([]plugin.Inst, error) {
 		if fields := objdumpOutputFunction.FindStringSubmatch(input); len(fields) == 2 {
 			function = fields[1]
 			continue
+		} else {
+			if fields := objdumpOutputFunctionLLVM.FindStringSubmatch(input); len(fields) == 3 {
+				function = fields[2]
+				continue
+			}
 		}
 		// Reset on unrecognized lines.
 		function, file, line = "", "", 0
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/cli.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/cli.go
index 9fc1eea1f0..492400c5f3 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/cli.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/cli.go
@@ -69,8 +69,9 @@ func parseFlags(o *plugin.Options) (*source, []string, error) {
 	flagHTTP := flag.String("http", "", "Present interactive web UI at the specified http host:port")
 	flagNoBrowser := flag.Bool("no_browser", false, "Skip opening a browswer for the interactive web UI")
 
-	// Flags used during command processing
-	installedFlags := installFlags(flag)
+	// Flags that set configuration properties.
+	cfg := currentConfig()
+	configFlagSetter := installConfigFlags(flag, &cfg)
 
 	flagCommands := make(map[string]*bool)
 	flagParamCommands := make(map[string]*string)
@@ -107,8 +108,8 @@ func parseFlags(o *plugin.Options) (*source, []string, error) {
 		}
 	}
 
-	// Report conflicting options
-	if err := updateFlags(installedFlags); err != nil {
+	// Apply any specified flags to cfg.
+	if err := configFlagSetter(); err != nil {
 		return nil, nil, err
 	}
 
@@ -124,7 +125,7 @@ func parseFlags(o *plugin.Options) (*source, []string, error) {
 		return nil, nil, errors.New("-no_browser only makes sense with -http")
 	}
 
-	si := pprofVariables["sample_index"].value
+	si := cfg.SampleIndex
 	si = sampleIndex(flagTotalDelay, si, "delay", "-total_delay", o.UI)
 	si = sampleIndex(flagMeanDelay, si, "delay", "-mean_delay", o.UI)
 	si = sampleIndex(flagContentions, si, "contentions", "-contentions", o.UI)
@@ -132,10 +133,10 @@ func parseFlags(o *plugin.Options) (*source, []string, error) {
 	si = sampleIndex(flagInUseObjects, si, "inuse_objects", "-inuse_objects", o.UI)
 	si = sampleIndex(flagAllocSpace, si, "alloc_space", "-alloc_space", o.UI)
 	si = sampleIndex(flagAllocObjects, si, "alloc_objects", "-alloc_objects", o.UI)
-	pprofVariables.set("sample_index", si)
+	cfg.SampleIndex = si
 
 	if *flagMeanDelay {
-		pprofVariables.set("mean", "true")
+		cfg.Mean = true
 	}
 
 	source := &source{
@@ -154,7 +155,7 @@ func parseFlags(o *plugin.Options) (*source, []string, error) {
 		return nil, nil, err
 	}
 
-	normalize := pprofVariables["normalize"].boolValue()
+	normalize := cfg.Normalize
 	if normalize && len(source.Base) == 0 {
 		return nil, nil, errors.New("must have base profile to normalize by")
 	}
@@ -163,6 +164,8 @@ func parseFlags(o *plugin.Options) (*source, []string, error) {
 	if bu, ok := o.Obj.(*binutils.Binutils); ok {
 		bu.SetTools(*flagTools)
 	}
+
+	setCurrentConfig(cfg)
 	return source, cmd, nil
 }
 
@@ -194,66 +197,72 @@ func dropEmpty(list []*string) []string {
 	return l
 }
 
-// installFlags creates command line flags for pprof variables.
-func installFlags(flag plugin.FlagSet) flagsInstalled {
-	f := flagsInstalled{
-		ints:    make(map[string]*int),
-		bools:   make(map[string]*bool),
-		floats:  make(map[string]*float64),
-		strings: make(map[string]*string),
-	}
-	for n, v := range pprofVariables {
-		switch v.kind {
-		case boolKind:
-			if v.group != "" {
-				// Set all radio variables to false to identify conflicts.
-				f.bools[n] = flag.Bool(n, false, v.help)
+// installConfigFlags creates command line flags for configuration
+// fields and returns a function which can be called after flags have
+// been parsed to copy any flags specified on the command line to
+// *cfg.
+func installConfigFlags(flag plugin.FlagSet, cfg *config) func() error {
+	// List of functions for setting the different parts of a config.
+	var setters []func()
+	var err error // Holds any errors encountered while running setters.
+
+	for _, field := range configFields {
+		n := field.name
+		help := configHelp[n]
+		var setter func()
+		switch ptr := cfg.fieldPtr(field).(type) {
+		case *bool:
+			f := flag.Bool(n, *ptr, help)
+			setter = func() { *ptr = *f }
+		case *int:
+			f := flag.Int(n, *ptr, help)
+			setter = func() { *ptr = *f }
+		case *float64:
+			f := flag.Float64(n, *ptr, help)
+			setter = func() { *ptr = *f }
+		case *string:
+			if len(field.choices) == 0 {
+				f := flag.String(n, *ptr, help)
+				setter = func() { *ptr = *f }
 			} else {
-				f.bools[n] = flag.Bool(n, v.boolValue(), v.help)
+				// Make a separate flag per possible choice.
+				// Set all flags to initially false so we can
+				// identify conflicts.
+				bools := make(map[string]*bool)
+				for _, choice := range field.choices {
+					bools[choice] = flag.Bool(choice, false, configHelp[choice])
+				}
+				setter = func() {
+					var set []string
+					for k, v := range bools {
+						if *v {
+							set = append(set, k)
+						}
+					}
+					switch len(set) {
+					case 0:
+						// Leave as default value.
+					case 1:
+						*ptr = set[0]
+					default:
+						err = fmt.Errorf("conflicting options set: %v", set)
+					}
+				}
 			}
-		case intKind:
-			f.ints[n] = flag.Int(n, v.intValue(), v.help)
-		case floatKind:
-			f.floats[n] = flag.Float64(n, v.floatValue(), v.help)
-		case stringKind:
-			f.strings[n] = flag.String(n, v.value, v.help)
 		}
+		setters = append(setters, setter)
 	}
-	return f
-}
 
-// updateFlags updates the pprof variables according to the flags
-// parsed in the command line.
-func updateFlags(f flagsInstalled) error {
-	vars := pprofVariables
-	groups := map[string]string{}
-	for n, v := range f.bools {
-		vars.set(n, fmt.Sprint(*v))
-		if *v {
-			g := vars[n].group
-			if g != "" && groups[g] != "" {
-				return fmt.Errorf("conflicting options %q and %q set", n, groups[g])
+	return func() error {
+		// Apply the setter for every flag.
+		for _, setter := range setters {
+			setter()
+			if err != nil {
+				return err
 			}
-			groups[g] = n
 		}
+		return nil
 	}
-	for n, v := range f.ints {
-		vars.set(n, fmt.Sprint(*v))
-	}
-	for n, v := range f.floats {
-		vars.set(n, fmt.Sprint(*v))
-	}
-	for n, v := range f.strings {
-		vars.set(n, *v)
-	}
-	return nil
-}
-
-type flagsInstalled struct {
-	ints    map[string]*int
-	bools   map[string]*bool
-	floats  map[string]*float64
-	strings map[string]*string
 }
 
 // isBuildID determines if the profile may contain a build ID, by
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/commands.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/commands.go
index f52471490a..4397e253e0 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/commands.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/commands.go
@@ -22,7 +22,6 @@ import (
 	"os/exec"
 	"runtime"
 	"sort"
-	"strconv"
 	"strings"
 	"time"
 
@@ -70,9 +69,7 @@ func AddCommand(cmd string, format int, post PostProcessor, desc, usage string)
 // SetVariableDefault sets the default value for a pprof
 // variable. This enables extensions to set their own defaults.
 func SetVariableDefault(variable, value string) {
-	if v := pprofVariables[variable]; v != nil {
-		v.value = value
-	}
+	configure(variable, value)
 }
 
 // PostProcessor is a function that applies post-processing to the report output
@@ -124,130 +121,132 @@ var pprofCommands = commands{
 	"weblist": {report.WebList, nil, invokeVisualizer("html", browsers()), true, "Display annotated source in a web browser", listHelp("weblist", false)},
 }
 
-// pprofVariables are the configuration parameters that affect the
-// reported generated by pprof.
-var pprofVariables = variables{
+// configHelp contains help text per configuration parameter.
+var configHelp = map[string]string{
 	// Filename for file-based output formats, stdout by default.
-	"output": &variable{stringKind, "", "", helpText("Output filename for file-based outputs")},
+	"output": helpText("Output filename for file-based outputs"),
 
 	// Comparisons.
-	"drop_negative": &variable{boolKind, "f", "", helpText(
+	"drop_negative": helpText(
 		"Ignore negative differences",
-		"Do not show any locations with values <0.")},
+		"Do not show any locations with values <0."),
 
 	// Graph handling options.
-	"call_tree": &variable{boolKind, "f", "", helpText(
+	"call_tree": helpText(
 		"Create a context-sensitive call tree",
-		"Treat locations reached through different paths as separate.")},
+		"Treat locations reached through different paths as separate."),
 
 	// Display options.
-	"relative_percentages": &variable{boolKind, "f", "", helpText(
+	"relative_percentages": helpText(
 		"Show percentages relative to focused subgraph",
 		"If unset, percentages are relative to full graph before focusing",
-		"to facilitate comparison with original graph.")},
-	"unit": &variable{stringKind, "minimum", "", helpText(
+		"to facilitate comparison with original graph."),
+	"unit": helpText(
 		"Measurement units to display",
 		"Scale the sample values to this unit.",
 		"For time-based profiles, use seconds, milliseconds, nanoseconds, etc.",
 		"For memory profiles, use megabytes, kilobytes, bytes, etc.",
-		"Using auto will scale each value independently to the most natural unit.")},
-	"compact_labels": &variable{boolKind, "f", "", "Show minimal headers"},
-	"source_path":    &variable{stringKind, "", "", "Search path for source files"},
-	"trim_path":      &variable{stringKind, "", "", "Path to trim from source paths before search"},
+		"Using auto will scale each value independently to the most natural unit."),
+	"compact_labels": "Show minimal headers",
+	"source_path":    "Search path for source files",
+	"trim_path":      "Path to trim from source paths before search",
+	"intel_syntax": helpText(
+		"Show assembly in Intel syntax",
+		"Only applicable to commands `disasm` and `weblist`"),
 
 	// Filtering options
-	"nodecount": &variable{intKind, "-1", "", helpText(
+	"nodecount": helpText(
 		"Max number of nodes to show",
 		"Uses heuristics to limit the number of locations to be displayed.",
-		"On graphs, dotted edges represent paths through nodes that have been removed.")},
-	"nodefraction": &variable{floatKind, "0.005", "", "Hide nodes below <f>*total"},
-	"edgefraction": &variable{floatKind, "0.001", "", "Hide edges below <f>*total"},
-	"trim": &variable{boolKind, "t", "", helpText(
+		"On graphs, dotted edges represent paths through nodes that have been removed."),
+	"nodefraction": "Hide nodes below <f>*total",
+	"edgefraction": "Hide edges below <f>*total",
+	"trim": helpText(
 		"Honor nodefraction/edgefraction/nodecount defaults",
-		"Set to false to get the full profile, without any trimming.")},
-	"focus": &variable{stringKind, "", "", helpText(
+		"Set to false to get the full profile, without any trimming."),
+	"focus": helpText(
 		"Restricts to samples going through a node matching regexp",
 		"Discard samples that do not include a node matching this regexp.",
-		"Matching includes the function name, filename or object name.")},
-	"ignore": &variable{stringKind, "", "", helpText(
+		"Matching includes the function name, filename or object name."),
+	"ignore": helpText(
 		"Skips paths going through any nodes matching regexp",
 		"If set, discard samples that include a node matching this regexp.",
-		"Matching includes the function name, filename or object name.")},
-	"prune_from": &variable{stringKind, "", "", helpText(
+		"Matching includes the function name, filename or object name."),
+	"prune_from": helpText(
 		"Drops any functions below the matched frame.",
 		"If set, any frames matching the specified regexp and any frames",
-		"below it will be dropped from each sample.")},
-	"hide": &variable{stringKind, "", "", helpText(
+		"below it will be dropped from each sample."),
+	"hide": helpText(
 		"Skips nodes matching regexp",
 		"Discard nodes that match this location.",
 		"Other nodes from samples that include this location will be shown.",
-		"Matching includes the function name, filename or object name.")},
-	"show": &variable{stringKind, "", "", helpText(
+		"Matching includes the function name, filename or object name."),
+	"show": helpText(
 		"Only show nodes matching regexp",
 		"If set, only show nodes that match this location.",
-		"Matching includes the function name, filename or object name.")},
-	"show_from": &variable{stringKind, "", "", helpText(
+		"Matching includes the function name, filename or object name."),
+	"show_from": helpText(
 		"Drops functions above the highest matched frame.",
 		"If set, all frames above the highest match are dropped from every sample.",
-		"Matching includes the function name, filename or object name.")},
-	"tagfocus": &variable{stringKind, "", "", helpText(
+		"Matching includes the function name, filename or object name."),
+	"tagfocus": helpText(
 		"Restricts to samples with tags in range or matched by regexp",
 		"Use name=value syntax to limit the matching to a specific tag.",
 		"Numeric tag filter examples: 1kb, 1kb:10kb, memory=32mb:",
-		"String tag filter examples: foo, foo.*bar, mytag=foo.*bar")},
-	"tagignore": &variable{stringKind, "", "", helpText(
+		"String tag filter examples: foo, foo.*bar, mytag=foo.*bar"),
+	"tagignore": helpText(
 		"Discard samples with tags in range or matched by regexp",
 		"Use name=value syntax to limit the matching to a specific tag.",
 		"Numeric tag filter examples: 1kb, 1kb:10kb, memory=32mb:",
-		"String tag filter examples: foo, foo.*bar, mytag=foo.*bar")},
-	"tagshow": &variable{stringKind, "", "", helpText(
+		"String tag filter examples: foo, foo.*bar, mytag=foo.*bar"),
+	"tagshow": helpText(
 		"Only consider tags matching this regexp",
-		"Discard tags that do not match this regexp")},
-	"taghide": &variable{stringKind, "", "", helpText(
+		"Discard tags that do not match this regexp"),
+	"taghide": helpText(
 		"Skip tags matching this regexp",
-		"Discard tags that match this regexp")},
+		"Discard tags that match this regexp"),
 	// Heap profile options
-	"divide_by": &variable{floatKind, "1", "", helpText(
+	"divide_by": helpText(
 		"Ratio to divide all samples before visualization",
-		"Divide all samples values by a constant, eg the number of processors or jobs.")},
-	"mean": &variable{boolKind, "f", "", helpText(
+		"Divide all samples values by a constant, eg the number of processors or jobs."),
+	"mean": helpText(
 		"Average sample value over first value (count)",
 		"For memory profiles, report average memory per allocation.",
-		"For time-based profiles, report average time per event.")},
-	"sample_index": &variable{stringKind, "", "", helpText(
+		"For time-based profiles, report average time per event."),
+	"sample_index": helpText(
 		"Sample value to report (0-based index or name)",
 		"Profiles contain multiple values per sample.",
-		"Use sample_index=i to select the ith value (starting at 0).")},
-	"normalize": &variable{boolKind, "f", "", helpText(
-		"Scales profile based on the base profile.")},
+		"Use sample_index=i to select the ith value (starting at 0)."),
+	"normalize": helpText(
+		"Scales profile based on the base profile."),
 
 	// Data sorting criteria
-	"flat": &variable{boolKind, "t", "cumulative", helpText("Sort entries based on own weight")},
-	"cum":  &variable{boolKind, "f", "cumulative", helpText("Sort entries based on cumulative weight")},
+	"flat": helpText("Sort entries based on own weight"),
+	"cum":  helpText("Sort entries based on cumulative weight"),
 
 	// Output granularity
-	"functions": &variable{boolKind, "t", "granularity", helpText(
+	"functions": helpText(
 		"Aggregate at the function level.",
-		"Ignores the filename where the function was defined.")},
-	"filefunctions": &variable{boolKind, "t", "granularity", helpText(
+		"Ignores the filename where the function was defined."),
+	"filefunctions": helpText(
 		"Aggregate at the function level.",
-		"Takes into account the filename where the function was defined.")},
-	"files": &variable{boolKind, "f", "granularity", "Aggregate at the file level."},
-	"lines": &variable{boolKind, "f", "granularity", "Aggregate at the source code line level."},
-	"addresses": &variable{boolKind, "f", "granularity", helpText(
+		"Takes into account the filename where the function was defined."),
+	"files": "Aggregate at the file level.",
+	"lines": "Aggregate at the source code line level.",
+	"addresses": helpText(
 		"Aggregate at the address level.",
-		"Includes functions' addresses in the output.")},
-	"noinlines": &variable{boolKind, "f", "", helpText(
+		"Includes functions' addresses in the output."),
+	"noinlines": helpText(
 		"Ignore inlines.",
-		"Attributes inlined functions to their first out-of-line caller.")},
+		"Attributes inlined functions to their first out-of-line caller."),
 }
 
 func helpText(s ...string) string {
 	return strings.Join(s, "\n") + "\n"
 }
 
-// usage returns a string describing the pprof commands and variables.
-// if commandLine is set, the output reflect cli usage.
+// usage returns a string describing the pprof commands and configuration
+// options.  if commandLine is set, the output reflect cli usage.
 func usage(commandLine bool) string {
 	var prefix string
 	if commandLine {
@@ -269,40 +268,33 @@ func usage(commandLine bool) string {
 	} else {
 		help = "  Commands:\n"
 		commands = append(commands, fmtHelp("o/options", "List options and their current values"))
-		commands = append(commands, fmtHelp("quit/exit/^D", "Exit pprof"))
+		commands = append(commands, fmtHelp("q/quit/exit/^D", "Exit pprof"))
 	}
 
 	help = help + strings.Join(commands, "\n") + "\n\n" +
 		"  Options:\n"
 
-	// Print help for variables after sorting them.
-	// Collect radio variables by their group name to print them together.
-	radioOptions := make(map[string][]string)
+	// Print help for configuration options after sorting them.
+	// Collect choices for multi-choice options print them together.
 	var variables []string
-	for name, vr := range pprofVariables {
-		if vr.group != "" {
-			radioOptions[vr.group] = append(radioOptions[vr.group], name)
+	var radioStrings []string
+	for _, f := range configFields {
+		if len(f.choices) == 0 {
+			variables = append(variables, fmtHelp(prefix+f.name, configHelp[f.name]))
 			continue
 		}
-		variables = append(variables, fmtHelp(prefix+name, vr.help))
-	}
-	sort.Strings(variables)
-
-	help = help + strings.Join(variables, "\n") + "\n\n" +
-		"  Option groups (only set one per group):\n"
-
-	var radioStrings []string
-	for radio, ops := range radioOptions {
-		sort.Strings(ops)
-		s := []string{fmtHelp(radio, "")}
-		for _, op := range ops {
-			s = append(s, "  "+fmtHelp(prefix+op, pprofVariables[op].help))
+		// Format help for for this group.
+		s := []string{fmtHelp(f.name, "")}
+		for _, choice := range f.choices {
+			s = append(s, "  "+fmtHelp(prefix+choice, configHelp[choice]))
 		}
-
 		radioStrings = append(radioStrings, strings.Join(s, "\n"))
 	}
+	sort.Strings(variables)
 	sort.Strings(radioStrings)
-	return help + strings.Join(radioStrings, "\n")
+	return help + strings.Join(variables, "\n") + "\n\n" +
+		"  Option groups (only set one per group):\n" +
+		strings.Join(radioStrings, "\n")
 }
 
 func reportHelp(c string, cum, redirect bool) string {
@@ -445,105 +437,8 @@ func invokeVisualizer(suffix string, visualizers []string) PostProcessor {
 	}
 }
 
-// variables describe the configuration parameters recognized by pprof.
-type variables map[string]*variable
-
-// variable is a single configuration parameter.
-type variable struct {
-	kind  int    // How to interpret the value, must be one of the enums below.
-	value string // Effective value. Only values appropriate for the Kind should be set.
-	group string // boolKind variables with the same Group != "" cannot be set simultaneously.
-	help  string // Text describing the variable, in multiple lines separated by newline.
-}
-
-const (
-	// variable.kind must be one of these variables.
-	boolKind = iota
-	intKind
-	floatKind
-	stringKind
-)
-
-// set updates the value of a variable, checking that the value is
-// suitable for the variable Kind.
-func (vars variables) set(name, value string) error {
-	v := vars[name]
-	if v == nil {
-		return fmt.Errorf("no variable %s", name)
-	}
-	var err error
-	switch v.kind {
-	case boolKind:
-		var b bool
-		if b, err = stringToBool(value); err == nil {
-			if v.group != "" && !b {
-				err = fmt.Errorf("%q can only be set to true", name)
-			}
-		}
-	case intKind:
-		_, err = strconv.Atoi(value)
-	case floatKind:
-		_, err = strconv.ParseFloat(value, 64)
-	case stringKind:
-		// Remove quotes, particularly useful for empty values.
-		if len(value) > 1 && strings.HasPrefix(value, `"`) && strings.HasSuffix(value, `"`) {
-			value = value[1 : len(value)-1]
-		}
-	}
-	if err != nil {
-		return err
-	}
-	vars[name].value = value
-	if group := vars[name].group; group != "" {
-		for vname, vvar := range vars {
-			if vvar.group == group && vname != name {
-				vvar.value = "f"
-			}
-		}
-	}
-	return err
-}
-
-// boolValue returns the value of a boolean variable.
-func (v *variable) boolValue() bool {
-	b, err := stringToBool(v.value)
-	if err != nil {
-		panic("unexpected value " + v.value + " for bool ")
-	}
-	return b
-}
-
-// intValue returns the value of an intKind variable.
-func (v *variable) intValue() int {
-	i, err := strconv.Atoi(v.value)
-	if err != nil {
-		panic("unexpected value " + v.value + " for int ")
-	}
-	return i
-}
-
-// floatValue returns the value of a Float variable.
-func (v *variable) floatValue() float64 {
-	f, err := strconv.ParseFloat(v.value, 64)
-	if err != nil {
-		panic("unexpected value " + v.value + " for float ")
-	}
-	return f
-}
-
-// stringValue returns a canonical representation for a variable.
-func (v *variable) stringValue() string {
-	switch v.kind {
-	case boolKind:
-		return fmt.Sprint(v.boolValue())
-	case intKind:
-		return fmt.Sprint(v.intValue())
-	case floatKind:
-		return fmt.Sprint(v.floatValue())
-	}
-	return v.value
-}
-
+// stringToBool is a custom parser for bools. We avoid using strconv.ParseBool
+// to remain compatible with old pprof behavior (e.g., treating "" as true).
 func stringToBool(s string) (bool, error) {
 	switch strings.ToLower(s) {
 	case "true", "t", "yes", "y", "1", "":
@@ -554,13 +449,3 @@ func stringToBool(s string) (bool, error) {
 		return false, fmt.Errorf(`illegal value "%s" for bool variable`, s)
 	}
 }
-
-// makeCopy returns a duplicate of a set of shell variables.
-func (vars variables) makeCopy() variables {
-	varscopy := make(variables, len(vars))
-	for n, v := range vars {
-		vcopy := *v
-		varscopy[n] = &vcopy
-	}
-	return varscopy
-}
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/config.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/config.go
new file mode 100644
index 0000000000..b3f82f22c9
--- /dev/null
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/config.go
@@ -0,0 +1,367 @@
+package driver
+
+import (
+	"fmt"
+	"net/url"
+	"reflect"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+// config holds settings for a single named config.
+// The JSON tag name for a field is used both for JSON encoding and as
+// a named variable.
+type config struct {
+	// Filename for file-based output formats, stdout by default.
+	Output string `json:"-"`
+
+	// Display options.
+	CallTree            bool    `json:"call_tree,omitempty"`
+	RelativePercentages bool    `json:"relative_percentages,omitempty"`
+	Unit                string  `json:"unit,omitempty"`
+	CompactLabels       bool    `json:"compact_labels,omitempty"`
+	SourcePath          string  `json:"-"`
+	TrimPath            string  `json:"-"`
+	IntelSyntax         bool    `json:"intel_syntax,omitempty"`
+	Mean                bool    `json:"mean,omitempty"`
+	SampleIndex         string  `json:"-"`
+	DivideBy            float64 `json:"-"`
+	Normalize           bool    `json:"normalize,omitempty"`
+	Sort                string  `json:"sort,omitempty"`
+
+	// Filtering options
+	DropNegative bool    `json:"drop_negative,omitempty"`
+	NodeCount    int     `json:"nodecount,omitempty"`
+	NodeFraction float64 `json:"nodefraction,omitempty"`
+	EdgeFraction float64 `json:"edgefraction,omitempty"`
+	Trim         bool    `json:"trim,omitempty"`
+	Focus        string  `json:"focus,omitempty"`
+	Ignore       string  `json:"ignore,omitempty"`
+	PruneFrom    string  `json:"prune_from,omitempty"`
+	Hide         string  `json:"hide,omitempty"`
+	Show         string  `json:"show,omitempty"`
+	ShowFrom     string  `json:"show_from,omitempty"`
+	TagFocus     string  `json:"tagfocus,omitempty"`
+	TagIgnore    string  `json:"tagignore,omitempty"`
+	TagShow      string  `json:"tagshow,omitempty"`
+	TagHide      string  `json:"taghide,omitempty"`
+	NoInlines    bool    `json:"noinlines,omitempty"`
+
+	// Output granularity
+	Granularity string `json:"granularity,omitempty"`
+}
+
+// defaultConfig returns the default configuration values; it is unaffected by
+// flags and interactive assignments.
+func defaultConfig() config {
+	return config{
+		Unit:         "minimum",
+		NodeCount:    -1,
+		NodeFraction: 0.005,
+		EdgeFraction: 0.001,
+		Trim:         true,
+		DivideBy:     1.0,
+		Sort:         "flat",
+		Granularity:  "functions",
+	}
+}
+
+// currentConfig holds the current configuration values; it is affected by
+// flags and interactive assignments.
+var currentCfg = defaultConfig()
+var currentMu sync.Mutex
+
+func currentConfig() config {
+	currentMu.Lock()
+	defer currentMu.Unlock()
+	return currentCfg
+}
+
+func setCurrentConfig(cfg config) {
+	currentMu.Lock()
+	defer currentMu.Unlock()
+	currentCfg = cfg
+}
+
+// configField contains metadata for a single configuration field.
+type configField struct {
+	name         string              // JSON field name/key in variables
+	urlparam     string              // URL parameter name
+	saved        bool                // Is field saved in settings?
+	field        reflect.StructField // Field in config
+	choices      []string            // Name Of variables in group
+	defaultValue string              // Default value for this field.
+}
+
+var (
+	configFields []configField // Precomputed metadata per config field
+
+	// configFieldMap holds an entry for every config field as well as an
+	// entry for every valid choice for a multi-choice field.
+	configFieldMap map[string]configField
+)
+
+func init() {
+	// Config names for fields that are not saved in settings and therefore
+	// do not have a JSON name.
+	notSaved := map[string]string{
+		// Not saved in settings, but present in URLs.
+		"SampleIndex": "sample_index",
+
+		// Following fields are also not placed in URLs.
+		"Output":     "output",
+		"SourcePath": "source_path",
+		"TrimPath":   "trim_path",
+		"DivideBy":   "divide_by",
+	}
+
+	// choices holds the list of allowed values for config fields that can
+	// take on one of a bounded set of values.
+	choices := map[string][]string{
+		"sort":        {"cum", "flat"},
+		"granularity": {"functions", "filefunctions", "files", "lines", "addresses"},
+	}
+
+	// urlparam holds the mapping from a config field name to the URL
+	// parameter used to hold that config field. If no entry is present for
+	// a name, the corresponding field is not saved in URLs.
+	urlparam := map[string]string{
+		"drop_negative":        "dropneg",
+		"call_tree":            "calltree",
+		"relative_percentages": "rel",
+		"unit":                 "unit",
+		"compact_labels":       "compact",
+		"intel_syntax":         "intel",
+		"nodecount":            "n",
+		"nodefraction":         "nf",
+		"edgefraction":         "ef",
+		"trim":                 "trim",
+		"focus":                "f",
+		"ignore":               "i",
+		"prune_from":           "prunefrom",
+		"hide":                 "h",
+		"show":                 "s",
+		"show_from":            "sf",
+		"tagfocus":             "tf",
+		"tagignore":            "ti",
+		"tagshow":              "ts",
+		"taghide":              "th",
+		"mean":                 "mean",
+		"sample_index":         "si",
+		"normalize":            "norm",
+		"sort":                 "sort",
+		"granularity":          "g",
+		"noinlines":            "noinlines",
+	}
+
+	def := defaultConfig()
+	configFieldMap = map[string]configField{}
+	t := reflect.TypeOf(config{})
+	for i, n := 0, t.NumField(); i < n; i++ {
+		field := t.Field(i)
+		js := strings.Split(field.Tag.Get("json"), ",")
+		if len(js) == 0 {
+			continue
+		}
+		// Get the configuration name for this field.
+		name := js[0]
+		if name == "-" {
+			name = notSaved[field.Name]
+			if name == "" {
+				// Not a configurable field.
+				continue
+			}
+		}
+		f := configField{
+			name:     name,
+			urlparam: urlparam[name],
+			saved:    (name == js[0]),
+			field:    field,
+			choices:  choices[name],
+		}
+		f.defaultValue = def.get(f)
+		configFields = append(configFields, f)
+		configFieldMap[f.name] = f
+		for _, choice := range f.choices {
+			configFieldMap[choice] = f
+		}
+	}
+}
+
+// fieldPtr returns a pointer to the field identified by f in *cfg.
+func (cfg *config) fieldPtr(f configField) interface{} {
+	// reflect.ValueOf: converts to reflect.Value
+	// Elem: dereferences cfg to make *cfg
+	// FieldByIndex: fetches the field
+	// Addr: takes address of field
+	// Interface: converts back from reflect.Value to a regular value
+	return reflect.ValueOf(cfg).Elem().FieldByIndex(f.field.Index).Addr().Interface()
+}
+
+// get returns the value of field f in cfg.
+func (cfg *config) get(f configField) string {
+	switch ptr := cfg.fieldPtr(f).(type) {
+	case *string:
+		return *ptr
+	case *int:
+		return fmt.Sprint(*ptr)
+	case *float64:
+		return fmt.Sprint(*ptr)
+	case *bool:
+		return fmt.Sprint(*ptr)
+	}
+	panic(fmt.Sprintf("unsupported config field type %v", f.field.Type))
+}
+
+// set sets the value of field f in cfg to value.
+func (cfg *config) set(f configField, value string) error {
+	switch ptr := cfg.fieldPtr(f).(type) {
+	case *string:
+		if len(f.choices) > 0 {
+			// Verify that value is one of the allowed choices.
+			for _, choice := range f.choices {
+				if choice == value {
+					*ptr = value
+					return nil
+				}
+			}
+			return fmt.Errorf("invalid %q value %q", f.name, value)
+		}
+		*ptr = value
+	case *int:
+		v, err := strconv.Atoi(value)
+		if err != nil {
+			return err
+		}
+		*ptr = v
+	case *float64:
+		v, err := strconv.ParseFloat(value, 64)
+		if err != nil {
+			return err
+		}
+		*ptr = v
+	case *bool:
+		v, err := stringToBool(value)
+		if err != nil {
+			return err
+		}
+		*ptr = v
+	default:
+		panic(fmt.Sprintf("unsupported config field type %v", f.field.Type))
+	}
+	return nil
+}
+
+// isConfigurable returns true if name is either the name of a config field, or
+// a valid value for a multi-choice config field.
+func isConfigurable(name string) bool {
+	_, ok := configFieldMap[name]
+	return ok
+}
+
+// isBoolConfig returns true if name is either name of a boolean config field,
+// or a valid value for a multi-choice config field.
+func isBoolConfig(name string) bool {
+	f, ok := configFieldMap[name]
+	if !ok {
+		return false
+	}
+	if name != f.name {
+		return true // name must be one possible value for the field
+	}
+	var cfg config
+	_, ok = cfg.fieldPtr(f).(*bool)
+	return ok
+}
+
+// completeConfig returns the list of configurable names starting with prefix.
+func completeConfig(prefix string) []string {
+	var result []string
+	for v := range configFieldMap {
+		if strings.HasPrefix(v, prefix) {
+			result = append(result, v)
+		}
+	}
+	return result
+}
+
+// configure stores the name=value mapping into the current config, correctly
+// handling the case when name identifies a particular choice in a field.
+func configure(name, value string) error {
+	currentMu.Lock()
+	defer currentMu.Unlock()
+	f, ok := configFieldMap[name]
+	if !ok {
+		return fmt.Errorf("unknown config field %q", name)
+	}
+	if f.name == name {
+		return currentCfg.set(f, value)
+	}
+	// name must be one of the choices. If value is true, set field-value
+	// to name.
+	if v, err := strconv.ParseBool(value); v && err == nil {
+		return currentCfg.set(f, name)
+	}
+	return fmt.Errorf("unknown config field %q", name)
+}
+
+// resetTransient sets all transient fields in *cfg to their currently
+// configured values.
+func (cfg *config) resetTransient() {
+	current := currentConfig()
+	cfg.Output = current.Output
+	cfg.SourcePath = current.SourcePath
+	cfg.TrimPath = current.TrimPath
+	cfg.DivideBy = current.DivideBy
+	cfg.SampleIndex = current.SampleIndex
+}
+
+// applyURL updates *cfg based on params.
+func (cfg *config) applyURL(params url.Values) error {
+	for _, f := range configFields {
+		var value string
+		if f.urlparam != "" {
+			value = params.Get(f.urlparam)
+		}
+		if value == "" {
+			continue
+		}
+		if err := cfg.set(f, value); err != nil {
+			return fmt.Errorf("error setting config field %s: %v", f.name, err)
+		}
+	}
+	return nil
+}
+
+// makeURL returns a URL based on initialURL that contains the config contents
+// as parameters.  The second result is true iff a parameter value was changed.
+func (cfg *config) makeURL(initialURL url.URL) (url.URL, bool) {
+	q := initialURL.Query()
+	changed := false
+	for _, f := range configFields {
+		if f.urlparam == "" || !f.saved {
+			continue
+		}
+		v := cfg.get(f)
+		if v == f.defaultValue {
+			v = "" // URL for of default value is the empty string.
+		} else if f.field.Type.Kind() == reflect.Bool {
+			// Shorten bool values to "f" or "t"
+			v = v[:1]
+		}
+		if q.Get(f.urlparam) == v {
+			continue
+		}
+		changed = true
+		if v == "" {
+			q.Del(f.urlparam)
+		} else {
+			q.Set(f.urlparam, v)
+		}
+	}
+	if changed {
+		initialURL.RawQuery = q.Encode()
+	}
+	return initialURL, changed
+}
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/driver.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/driver.go
index 1be749aa32..878f2e1ead 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/driver.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/driver.go
@@ -50,7 +50,7 @@ func PProf(eo *plugin.Options) error {
 	}
 
 	if cmd != nil {
-		return generateReport(p, cmd, pprofVariables, o)
+		return generateReport(p, cmd, currentConfig(), o)
 	}
 
 	if src.HTTPHostport != "" {
@@ -59,7 +59,7 @@ func PProf(eo *plugin.Options) error {
 	return interactive(p, o)
 }
 
-func generateRawReport(p *profile.Profile, cmd []string, vars variables, o *plugin.Options) (*command, *report.Report, error) {
+func generateRawReport(p *profile.Profile, cmd []string, cfg config, o *plugin.Options) (*command, *report.Report, error) {
 	p = p.Copy() // Prevent modification to the incoming profile.
 
 	// Identify units of numeric tags in profile.
@@ -71,16 +71,16 @@ func generateRawReport(p *profile.Profile, cmd []string, vars variables, o *plug
 		panic("unexpected nil command")
 	}
 
-	vars = applyCommandOverrides(cmd[0], c.format, vars)
+	cfg = applyCommandOverrides(cmd[0], c.format, cfg)
 
 	// Delay focus after configuring report to get percentages on all samples.
-	relative := vars["relative_percentages"].boolValue()
+	relative := cfg.RelativePercentages
 	if relative {
-		if err := applyFocus(p, numLabelUnits, vars, o.UI); err != nil {
+		if err := applyFocus(p, numLabelUnits, cfg, o.UI); err != nil {
 			return nil, nil, err
 		}
 	}
-	ropt, err := reportOptions(p, numLabelUnits, vars)
+	ropt, err := reportOptions(p, numLabelUnits, cfg)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -95,19 +95,19 @@ func generateRawReport(p *profile.Profile, cmd []string, vars variables, o *plug
 
 	rpt := report.New(p, ropt)
 	if !relative {
-		if err := applyFocus(p, numLabelUnits, vars, o.UI); err != nil {
+		if err := applyFocus(p, numLabelUnits, cfg, o.UI); err != nil {
 			return nil, nil, err
 		}
 	}
-	if err := aggregate(p, vars); err != nil {
+	if err := aggregate(p, cfg); err != nil {
 		return nil, nil, err
 	}
 
 	return c, rpt, nil
 }
 
-func generateReport(p *profile.Profile, cmd []string, vars variables, o *plugin.Options) error {
-	c, rpt, err := generateRawReport(p, cmd, vars, o)
+func generateReport(p *profile.Profile, cmd []string, cfg config, o *plugin.Options) error {
+	c, rpt, err := generateRawReport(p, cmd, cfg, o)
 	if err != nil {
 		return err
 	}
@@ -129,7 +129,7 @@ func generateReport(p *profile.Profile, cmd []string, vars variables, o *plugin.
 	}
 
 	// If no output is specified, use default visualizer.
-	output := vars["output"].value
+	output := cfg.Output
 	if output == "" {
 		if c.visualizer != nil {
 			return c.visualizer(src, os.Stdout, o.UI)
@@ -151,7 +151,7 @@ func generateReport(p *profile.Profile, cmd []string, vars variables, o *plugin.
 	return out.Close()
 }
 
-func applyCommandOverrides(cmd string, outputFormat int, v variables) variables {
+func applyCommandOverrides(cmd string, outputFormat int, cfg config) config {
 	// Some report types override the trim flag to false below. This is to make
 	// sure the default heuristics of excluding insignificant nodes and edges
 	// from the call graph do not apply. One example where it is important is
@@ -160,55 +160,55 @@ func applyCommandOverrides(cmd string, outputFormat int, v variables) variables
 	// data is selected. So, with trimming enabled, the report could end up
 	// showing no data if the specified function is "uninteresting" as far as the
 	// trimming is concerned.
-	trim := v["trim"].boolValue()
+	trim := cfg.Trim
 
 	switch cmd {
 	case "disasm", "weblist":
 		trim = false
-		v.set("addresses", "t")
+		cfg.Granularity = "addresses"
 		// Force the 'noinlines' mode so that source locations for a given address
 		// collapse and there is only one for the given address. Without this
 		// cumulative metrics would be double-counted when annotating the assembly.
 		// This is because the merge is done by address and in case of an inlined
 		// stack each of the inlined entries is a separate callgraph node.
-		v.set("noinlines", "t")
+		cfg.NoInlines = true
 	case "peek":
 		trim = false
 	case "list":
 		trim = false
-		v.set("lines", "t")
+		cfg.Granularity = "lines"
 		// Do not force 'noinlines' to be false so that specifying
 		// "-list foo -noinlines" is supported and works as expected.
 	case "text", "top", "topproto":
-		if v["nodecount"].intValue() == -1 {
-			v.set("nodecount", "0")
+		if cfg.NodeCount == -1 {
+			cfg.NodeCount = 0
 		}
 	default:
-		if v["nodecount"].intValue() == -1 {
-			v.set("nodecount", "80")
+		if cfg.NodeCount == -1 {
+			cfg.NodeCount = 80
 		}
 	}
 
 	switch outputFormat {
 	case report.Proto, report.Raw, report.Callgrind:
 		trim = false
-		v.set("addresses", "t")
-		v.set("noinlines", "f")
+		cfg.Granularity = "addresses"
+		cfg.NoInlines = false
 	}
 
 	if !trim {
-		v.set("nodecount", "0")
-		v.set("nodefraction", "0")
-		v.set("edgefraction", "0")
+		cfg.NodeCount = 0
+		cfg.NodeFraction = 0
+		cfg.EdgeFraction = 0
 	}
-	return v
+	return cfg
 }
 
-func aggregate(prof *profile.Profile, v variables) error {
+func aggregate(prof *profile.Profile, cfg config) error {
 	var function, filename, linenumber, address bool
-	inlines := !v["noinlines"].boolValue()
-	switch {
-	case v["addresses"].boolValue():
+	inlines := !cfg.NoInlines
+	switch cfg.Granularity {
+	case "addresses":
 		if inlines {
 			return nil
 		}
@@ -216,15 +216,15 @@ func aggregate(prof *profile.Profile, v variables) error {
 		filename = true
 		linenumber = true
 		address = true
-	case v["lines"].boolValue():
+	case "lines":
 		function = true
 		filename = true
 		linenumber = true
-	case v["files"].boolValue():
+	case "files":
 		filename = true
-	case v["functions"].boolValue():
+	case "functions":
 		function = true
-	case v["filefunctions"].boolValue():
+	case "filefunctions":
 		function = true
 		filename = true
 	default:
@@ -233,8 +233,8 @@ func aggregate(prof *profile.Profile, v variables) error {
 	return prof.Aggregate(inlines, function, filename, linenumber, address)
 }
 
-func reportOptions(p *profile.Profile, numLabelUnits map[string]string, vars variables) (*report.Options, error) {
-	si, mean := vars["sample_index"].value, vars["mean"].boolValue()
+func reportOptions(p *profile.Profile, numLabelUnits map[string]string, cfg config) (*report.Options, error) {
+	si, mean := cfg.SampleIndex, cfg.Mean
 	value, meanDiv, sample, err := sampleFormat(p, si, mean)
 	if err != nil {
 		return nil, err
@@ -245,29 +245,37 @@ func reportOptions(p *profile.Profile, numLabelUnits map[string]string, vars var
 		stype = "mean_" + stype
 	}
 
-	if vars["divide_by"].floatValue() == 0 {
+	if cfg.DivideBy == 0 {
 		return nil, fmt.Errorf("zero divisor specified")
 	}
 
 	var filters []string
-	for _, k := range []string{"focus", "ignore", "hide", "show", "show_from", "tagfocus", "tagignore", "tagshow", "taghide"} {
-		v := vars[k].value
+	addFilter := func(k string, v string) {
 		if v != "" {
 			filters = append(filters, k+"="+v)
 		}
 	}
+	addFilter("focus", cfg.Focus)
+	addFilter("ignore", cfg.Ignore)
+	addFilter("hide", cfg.Hide)
+	addFilter("show", cfg.Show)
+	addFilter("show_from", cfg.ShowFrom)
+	addFilter("tagfocus", cfg.TagFocus)
+	addFilter("tagignore", cfg.TagIgnore)
+	addFilter("tagshow", cfg.TagShow)
+	addFilter("taghide", cfg.TagHide)
 
 	ropt := &report.Options{
-		CumSort:      vars["cum"].boolValue(),
-		CallTree:     vars["call_tree"].boolValue(),
-		DropNegative: vars["drop_negative"].boolValue(),
+		CumSort:      cfg.Sort == "cum",
+		CallTree:     cfg.CallTree,
+		DropNegative: cfg.DropNegative,
 
-		CompactLabels: vars["compact_labels"].boolValue(),
-		Ratio:         1 / vars["divide_by"].floatValue(),
+		CompactLabels: cfg.CompactLabels,
+		Ratio:         1 / cfg.DivideBy,
 
-		NodeCount:    vars["nodecount"].intValue(),
-		NodeFraction: vars["nodefraction"].floatValue(),
-		EdgeFraction: vars["edgefraction"].floatValue(),
+		NodeCount:    cfg.NodeCount,
+		NodeFraction: cfg.NodeFraction,
+		EdgeFraction: cfg.EdgeFraction,
 
 		ActiveFilters: filters,
 		NumLabelUnits: numLabelUnits,
@@ -277,10 +285,12 @@ func reportOptions(p *profile.Profile, numLabelUnits map[string]string, vars var
 		SampleType:        stype,
 		SampleUnit:        sample.Unit,
 
-		OutputUnit: vars["unit"].value,
+		OutputUnit: cfg.Unit,
 
-		SourcePath: vars["source_path"].stringValue(),
-		TrimPath:   vars["trim_path"].stringValue(),
+		SourcePath: cfg.SourcePath,
+		TrimPath:   cfg.TrimPath,
+
+		IntelSyntax: cfg.IntelSyntax,
 	}
 
 	if len(p.Mapping) > 0 && p.Mapping[0].File != "" {
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/driver_focus.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/driver_focus.go
index af7b8d478a..fd05adb146 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/driver_focus.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/driver_focus.go
@@ -28,15 +28,15 @@ import (
 var tagFilterRangeRx = regexp.MustCompile("([+-]?[[:digit:]]+)([[:alpha:]]+)?")
 
 // applyFocus filters samples based on the focus/ignore options
-func applyFocus(prof *profile.Profile, numLabelUnits map[string]string, v variables, ui plugin.UI) error {
-	focus, err := compileRegexOption("focus", v["focus"].value, nil)
-	ignore, err := compileRegexOption("ignore", v["ignore"].value, err)
-	hide, err := compileRegexOption("hide", v["hide"].value, err)
-	show, err := compileRegexOption("show", v["show"].value, err)
-	showfrom, err := compileRegexOption("show_from", v["show_from"].value, err)
-	tagfocus, err := compileTagFilter("tagfocus", v["tagfocus"].value, numLabelUnits, ui, err)
-	tagignore, err := compileTagFilter("tagignore", v["tagignore"].value, numLabelUnits, ui, err)
-	prunefrom, err := compileRegexOption("prune_from", v["prune_from"].value, err)
+func applyFocus(prof *profile.Profile, numLabelUnits map[string]string, cfg config, ui plugin.UI) error {
+	focus, err := compileRegexOption("focus", cfg.Focus, nil)
+	ignore, err := compileRegexOption("ignore", cfg.Ignore, err)
+	hide, err := compileRegexOption("hide", cfg.Hide, err)
+	show, err := compileRegexOption("show", cfg.Show, err)
+	showfrom, err := compileRegexOption("show_from", cfg.ShowFrom, err)
+	tagfocus, err := compileTagFilter("tagfocus", cfg.TagFocus, numLabelUnits, ui, err)
+	tagignore, err := compileTagFilter("tagignore", cfg.TagIgnore, numLabelUnits, ui, err)
+	prunefrom, err := compileRegexOption("prune_from", cfg.PruneFrom, err)
 	if err != nil {
 		return err
 	}
@@ -54,11 +54,11 @@ func applyFocus(prof *profile.Profile, numLabelUnits map[string]string, v variab
 	warnNoMatches(tagfocus == nil || tfm, "TagFocus", ui)
 	warnNoMatches(tagignore == nil || tim, "TagIgnore", ui)
 
-	tagshow, err := compileRegexOption("tagshow", v["tagshow"].value, err)
-	taghide, err := compileRegexOption("taghide", v["taghide"].value, err)
+	tagshow, err := compileRegexOption("tagshow", cfg.TagShow, err)
+	taghide, err := compileRegexOption("taghide", cfg.TagHide, err)
 	tns, tnh := prof.FilterTagsByName(tagshow, taghide)
 	warnNoMatches(tagshow == nil || tns, "TagShow", ui)
-	warnNoMatches(tagignore == nil || tnh, "TagHide", ui)
+	warnNoMatches(taghide == nil || tnh, "TagHide", ui)
 
 	if prunefrom != nil {
 		prof.PruneFrom(prunefrom)
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/flamegraph.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/flamegraph.go
index 13613cff86..fbeb765dbc 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/flamegraph.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/flamegraph.go
@@ -38,7 +38,10 @@ type treeNode struct {
 func (ui *webInterface) flamegraph(w http.ResponseWriter, req *http.Request) {
 	// Force the call tree so that the graph is a tree.
 	// Also do not trim the tree so that the flame graph contains all functions.
-	rpt, errList := ui.makeReport(w, req, []string{"svg"}, "call_tree", "true", "trim", "false")
+	rpt, errList := ui.makeReport(w, req, []string{"svg"}, func(cfg *config) {
+		cfg.CallTree = true
+		cfg.Trim = false
+	})
 	if rpt == nil {
 		return // error already reported
 	}
@@ -96,7 +99,7 @@ func (ui *webInterface) flamegraph(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	ui.render(w, "flamegraph", rpt, errList, config.Labels, webArgs{
+	ui.render(w, req, "flamegraph", rpt, errList, config.Labels, webArgs{
 		FlameGraph: template.JS(b),
 		Nodes:      nodeArr,
 	})
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/interactive.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/interactive.go
index 3a458b0b77..777fb90bfb 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/interactive.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/interactive.go
@@ -34,17 +34,14 @@ var tailDigitsRE = regexp.MustCompile("[0-9]+$")
 func interactive(p *profile.Profile, o *plugin.Options) error {
 	// Enter command processing loop.
 	o.UI.SetAutoComplete(newCompleter(functionNames(p)))
-	pprofVariables.set("compact_labels", "true")
-	pprofVariables["sample_index"].help += fmt.Sprintf("Or use sample_index=name, with name in %v.\n", sampleTypes(p))
+	configure("compact_labels", "true")
+	configHelp["sample_index"] += fmt.Sprintf("Or use sample_index=name, with name in %v.\n", sampleTypes(p))
 
 	// Do not wait for the visualizer to complete, to allow multiple
 	// graphs to be visualized simultaneously.
 	interactiveMode = true
 	shortcuts := profileShortcuts(p)
 
-	// Get all groups in pprofVariables to allow for clearer error messages.
-	groups := groupOptions(pprofVariables)
-
 	greetings(p, o.UI)
 	for {
 		input, err := o.UI.ReadLine("(pprof) ")
@@ -69,7 +66,12 @@ func interactive(p *profile.Profile, o *plugin.Options) error {
 					}
 					value = strings.TrimSpace(value)
 				}
-				if v := pprofVariables[name]; v != nil {
+				if isConfigurable(name) {
+					// All non-bool options require inputs
+					if len(s) == 1 && !isBoolConfig(name) {
+						o.UI.PrintErr(fmt.Errorf("please specify a value, e.g. %s=<val>", name))
+						continue
+					}
 					if name == "sample_index" {
 						// Error check sample_index=xxx to ensure xxx is a valid sample type.
 						index, err := p.SampleIndexByName(value)
@@ -77,22 +79,16 @@ func interactive(p *profile.Profile, o *plugin.Options) error {
 							o.UI.PrintErr(err)
 							continue
 						}
+						if index < 0 || index >= len(p.SampleType) {
+							o.UI.PrintErr(fmt.Errorf("invalid sample_index %q", value))
+							continue
+						}
 						value = p.SampleType[index].Type
 					}
-					if err := pprofVariables.set(name, value); err != nil {
-						o.UI.PrintErr(err)
-					}
-					continue
-				}
-				// Allow group=variable syntax by converting into variable="".
-				if v := pprofVariables[value]; v != nil && v.group == name {
-					if err := pprofVariables.set(value, ""); err != nil {
+					if err := configure(name, value); err != nil {
 						o.UI.PrintErr(err)
 					}
 					continue
-				} else if okValues := groups[name]; okValues != nil {
-					o.UI.PrintErr(fmt.Errorf("unrecognized value for %s: %q. Use one of %s", name, value, strings.Join(okValues, ", ")))
-					continue
 				}
 			}
 
@@ -105,16 +101,16 @@ func interactive(p *profile.Profile, o *plugin.Options) error {
 			case "o", "options":
 				printCurrentOptions(p, o.UI)
 				continue
-			case "exit", "quit":
+			case "exit", "quit", "q":
 				return nil
 			case "help":
 				commandHelp(strings.Join(tokens[1:], " "), o.UI)
 				continue
 			}
 
-			args, vars, err := parseCommandLine(tokens)
+			args, cfg, err := parseCommandLine(tokens)
 			if err == nil {
-				err = generateReportWrapper(p, args, vars, o)
+				err = generateReportWrapper(p, args, cfg, o)
 			}
 
 			if err != nil {
@@ -124,30 +120,13 @@ func interactive(p *profile.Profile, o *plugin.Options) error {
 	}
 }
 
-// groupOptions returns a map containing all non-empty groups
-// mapped to an array of the option names in that group in
-// sorted order.
-func groupOptions(vars variables) map[string][]string {
-	groups := make(map[string][]string)
-	for name, option := range vars {
-		group := option.group
-		if group != "" {
-			groups[group] = append(groups[group], name)
-		}
-	}
-	for _, names := range groups {
-		sort.Strings(names)
-	}
-	return groups
-}
-
 var generateReportWrapper = generateReport // For testing purposes.
 
 // greetings prints a brief welcome and some overall profile
 // information before accepting interactive commands.
 func greetings(p *profile.Profile, ui plugin.UI) {
 	numLabelUnits := identifyNumLabelUnits(p, ui)
-	ropt, err := reportOptions(p, numLabelUnits, pprofVariables)
+	ropt, err := reportOptions(p, numLabelUnits, currentConfig())
 	if err == nil {
 		rpt := report.New(p, ropt)
 		ui.Print(strings.Join(report.ProfileLabels(rpt), "\n"))
@@ -200,27 +179,16 @@ func sampleTypes(p *profile.Profile) []string {
 
 func printCurrentOptions(p *profile.Profile, ui plugin.UI) {
 	var args []string
-	type groupInfo struct {
-		set    string
-		values []string
-	}
-	groups := make(map[string]*groupInfo)
-	for n, o := range pprofVariables {
-		v := o.stringValue()
+	current := currentConfig()
+	for _, f := range configFields {
+		n := f.name
+		v := current.get(f)
 		comment := ""
-		if g := o.group; g != "" {
-			gi, ok := groups[g]
-			if !ok {
-				gi = &groupInfo{}
-				groups[g] = gi
-			}
-			if o.boolValue() {
-				gi.set = n
-			}
-			gi.values = append(gi.values, n)
-			continue
-		}
 		switch {
+		case len(f.choices) > 0:
+			values := append([]string{}, f.choices...)
+			sort.Strings(values)
+			comment = "[" + strings.Join(values, " | ") + "]"
 		case n == "sample_index":
 			st := sampleTypes(p)
 			if v == "" {
@@ -242,18 +210,13 @@ func printCurrentOptions(p *profile.Profile, ui plugin.UI) {
 		}
 		args = append(args, fmt.Sprintf("  %-25s = %-20s %s", n, v, comment))
 	}
-	for g, vars := range groups {
-		sort.Strings(vars.values)
-		comment := commentStart + " [" + strings.Join(vars.values, " | ") + "]"
-		args = append(args, fmt.Sprintf("  %-25s = %-20s %s", g, vars.set, comment))
-	}
 	sort.Strings(args)
 	ui.Print(strings.Join(args, "\n"))
 }
 
 // parseCommandLine parses a command and returns the pprof command to
-// execute and a set of variables for the report.
-func parseCommandLine(input []string) ([]string, variables, error) {
+// execute and the configuration to use for the report.
+func parseCommandLine(input []string) ([]string, config, error) {
 	cmd, args := input[:1], input[1:]
 	name := cmd[0]
 
@@ -267,25 +230,32 @@ func parseCommandLine(input []string) ([]string, variables, error) {
 		}
 	}
 	if c == nil {
-		return nil, nil, fmt.Errorf("unrecognized command: %q", name)
+		if _, ok := configHelp[name]; ok {
+			value := "<val>"
+			if len(args) > 0 {
+				value = args[0]
+			}
+			return nil, config{}, fmt.Errorf("did you mean: %s=%s", name, value)
+		}
+		return nil, config{}, fmt.Errorf("unrecognized command: %q", name)
 	}
 
 	if c.hasParam {
 		if len(args) == 0 {
-			return nil, nil, fmt.Errorf("command %s requires an argument", name)
+			return nil, config{}, fmt.Errorf("command %s requires an argument", name)
 		}
 		cmd = append(cmd, args[0])
 		args = args[1:]
 	}
 
-	// Copy the variables as options set in the command line are not persistent.
-	vcopy := pprofVariables.makeCopy()
+	// Copy config since options set in the command line should not persist.
+	vcopy := currentConfig()
 
 	var focus, ignore string
 	for i := 0; i < len(args); i++ {
 		t := args[i]
-		if _, err := strconv.ParseInt(t, 10, 32); err == nil {
-			vcopy.set("nodecount", t)
+		if n, err := strconv.ParseInt(t, 10, 32); err == nil {
+			vcopy.NodeCount = int(n)
 			continue
 		}
 		switch t[0] {
@@ -294,14 +264,14 @@ func parseCommandLine(input []string) ([]string, variables, error) {
 			if outputFile == "" {
 				i++
 				if i >= len(args) {
-					return nil, nil, fmt.Errorf("unexpected end of line after >")
+					return nil, config{}, fmt.Errorf("unexpected end of line after >")
 				}
 				outputFile = args[i]
 			}
-			vcopy.set("output", outputFile)
+			vcopy.Output = outputFile
 		case '-':
 			if t == "--cum" || t == "-cum" {
-				vcopy.set("cum", "t")
+				vcopy.Sort = "cum"
 				continue
 			}
 			ignore = catRegex(ignore, t[1:])
@@ -311,30 +281,27 @@ func parseCommandLine(input []string) ([]string, variables, error) {
 	}
 
 	if name == "tags" {
-		updateFocusIgnore(vcopy, "tag", focus, ignore)
+		if focus != "" {
+			vcopy.TagFocus = focus
+		}
+		if ignore != "" {
+			vcopy.TagIgnore = ignore
+		}
 	} else {
-		updateFocusIgnore(vcopy, "", focus, ignore)
+		if focus != "" {
+			vcopy.Focus = focus
+		}
+		if ignore != "" {
+			vcopy.Ignore = ignore
+		}
 	}
-
-	if vcopy["nodecount"].intValue() == -1 && (name == "text" || name == "top") {
-		vcopy.set("nodecount", "10")
+	if vcopy.NodeCount == -1 && (name == "text" || name == "top") {
+		vcopy.NodeCount = 10
 	}
 
 	return cmd, vcopy, nil
 }
 
-func updateFocusIgnore(v variables, prefix, f, i string) {
-	if f != "" {
-		focus := prefix + "focus"
-		v.set(focus, catRegex(v[focus].value, f))
-	}
-
-	if i != "" {
-		ignore := prefix + "ignore"
-		v.set(ignore, catRegex(v[ignore].value, i))
-	}
-}
-
 func catRegex(a, b string) string {
 	if a != "" && b != "" {
 		return a + "|" + b
@@ -362,8 +329,8 @@ func commandHelp(args string, ui plugin.UI) {
 		return
 	}
 
-	if v := pprofVariables[args]; v != nil {
-		ui.Print(v.help + "\n")
+	if help, ok := configHelp[args]; ok {
+		ui.Print(help + "\n")
 		return
 	}
 
@@ -373,18 +340,17 @@ func commandHelp(args string, ui plugin.UI) {
 // newCompleter creates an autocompletion function for a set of commands.
 func newCompleter(fns []string) func(string) string {
 	return func(line string) string {
-		v := pprofVariables
 		switch tokens := strings.Fields(line); len(tokens) {
 		case 0:
 			// Nothing to complete
 		case 1:
 			// Single token -- complete command name
-			if match := matchVariableOrCommand(v, tokens[0]); match != "" {
+			if match := matchVariableOrCommand(tokens[0]); match != "" {
 				return match
 			}
 		case 2:
 			if tokens[0] == "help" {
-				if match := matchVariableOrCommand(v, tokens[1]); match != "" {
+				if match := matchVariableOrCommand(tokens[1]); match != "" {
 					return tokens[0] + " " + match
 				}
 				return line
@@ -408,26 +374,19 @@ func newCompleter(fns []string) func(string) string {
 }
 
 // matchVariableOrCommand attempts to match a string token to the prefix of a Command.
-func matchVariableOrCommand(v variables, token string) string {
+func matchVariableOrCommand(token string) string {
 	token = strings.ToLower(token)
-	found := ""
+	var matches []string
 	for cmd := range pprofCommands {
 		if strings.HasPrefix(cmd, token) {
-			if found != "" {
-				return ""
-			}
-			found = cmd
+			matches = append(matches, cmd)
 		}
 	}
-	for variable := range v {
-		if strings.HasPrefix(variable, token) {
-			if found != "" {
-				return ""
-			}
-			found = variable
-		}
+	matches = append(matches, completeConfig(token)...)
+	if len(matches) == 1 {
+		return matches[0]
 	}
-	return found
+	return ""
 }
 
 // functionCompleter replaces provided substring with a function
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/settings.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/settings.go
new file mode 100644
index 0000000000..f72314b185
--- /dev/null
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/settings.go
@@ -0,0 +1,157 @@
+package driver
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/url"
+	"os"
+	"path/filepath"
+)
+
+// settings holds pprof settings.
+type settings struct {
+	// Configs holds a list of named UI configurations.
+	Configs []namedConfig `json:"configs"`
+}
+
+// namedConfig associates a name with a config.
+type namedConfig struct {
+	Name string `json:"name"`
+	config
+}
+
+// settingsFileName returns the name of the file where settings should be saved.
+func settingsFileName() (string, error) {
+	// Return "pprof/settings.json" under os.UserConfigDir().
+	dir, err := os.UserConfigDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(dir, "pprof", "settings.json"), nil
+}
+
+// readSettings reads settings from fname.
+func readSettings(fname string) (*settings, error) {
+	data, err := ioutil.ReadFile(fname)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return &settings{}, nil
+		}
+		return nil, fmt.Errorf("could not read settings: %w", err)
+	}
+	settings := &settings{}
+	if err := json.Unmarshal(data, settings); err != nil {
+		return nil, fmt.Errorf("could not parse settings: %w", err)
+	}
+	for i := range settings.Configs {
+		settings.Configs[i].resetTransient()
+	}
+	return settings, nil
+}
+
+// writeSettings saves settings to fname.
+func writeSettings(fname string, settings *settings) error {
+	data, err := json.MarshalIndent(settings, "", "  ")
+	if err != nil {
+		return fmt.Errorf("could not encode settings: %w", err)
+	}
+
+	// create the settings directory if it does not exist
+	// XDG specifies permissions 0700 when creating settings dirs:
+	// https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
+	if err := os.MkdirAll(filepath.Dir(fname), 0700); err != nil {
+		return fmt.Errorf("failed to create settings directory: %w", err)
+	}
+
+	if err := ioutil.WriteFile(fname, data, 0644); err != nil {
+		return fmt.Errorf("failed to write settings: %w", err)
+	}
+	return nil
+}
+
+// configMenuEntry holds information for a single config menu entry.
+type configMenuEntry struct {
+	Name       string
+	URL        string
+	Current    bool // Is this the currently selected config?
+	UserConfig bool // Is this a user-provided config?
+}
+
+// configMenu returns a list of items to add to a menu in the web UI.
+func configMenu(fname string, url url.URL) []configMenuEntry {
+	// Start with system configs.
+	configs := []namedConfig{{Name: "Default", config: defaultConfig()}}
+	if settings, err := readSettings(fname); err == nil {
+		// Add user configs.
+		configs = append(configs, settings.Configs...)
+	}
+
+	// Convert to menu entries.
+	result := make([]configMenuEntry, len(configs))
+	lastMatch := -1
+	for i, cfg := range configs {
+		dst, changed := cfg.config.makeURL(url)
+		if !changed {
+			lastMatch = i
+		}
+		result[i] = configMenuEntry{
+			Name:       cfg.Name,
+			URL:        dst.String(),
+			UserConfig: (i != 0),
+		}
+	}
+	// Mark the last matching config as currennt
+	if lastMatch >= 0 {
+		result[lastMatch].Current = true
+	}
+	return result
+}
+
+// editSettings edits settings by applying fn to them.
+func editSettings(fname string, fn func(s *settings) error) error {
+	settings, err := readSettings(fname)
+	if err != nil {
+		return err
+	}
+	if err := fn(settings); err != nil {
+		return err
+	}
+	return writeSettings(fname, settings)
+}
+
+// setConfig saves the config specified in request to fname.
+func setConfig(fname string, request url.URL) error {
+	q := request.Query()
+	name := q.Get("config")
+	if name == "" {
+		return fmt.Errorf("invalid config name")
+	}
+	cfg := currentConfig()
+	if err := cfg.applyURL(q); err != nil {
+		return err
+	}
+	return editSettings(fname, func(s *settings) error {
+		for i, c := range s.Configs {
+			if c.Name == name {
+				s.Configs[i].config = cfg
+				return nil
+			}
+		}
+		s.Configs = append(s.Configs, namedConfig{Name: name, config: cfg})
+		return nil
+	})
+}
+
+// removeConfig removes config from fname.
+func removeConfig(fname, config string) error {
+	return editSettings(fname, func(s *settings) error {
+		for i, c := range s.Configs {
+			if c.Name == config {
+				s.Configs = append(s.Configs[:i], s.Configs[i+1:]...)
+				return nil
+			}
+		}
+		return fmt.Errorf("config %s not found", config)
+	})
+}
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/tempfile.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/tempfile.go
index 28679f1c15..b6c8776ff8 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/tempfile.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/tempfile.go
@@ -24,9 +24,11 @@ import (
 // newTempFile returns a new output file in dir with the provided prefix and suffix.
 func newTempFile(dir, prefix, suffix string) (*os.File, error) {
 	for index := 1; index < 10000; index++ {
-		path := filepath.Join(dir, fmt.Sprintf("%s%03d%s", prefix, index, suffix))
-		if _, err := os.Stat(path); err != nil {
-			return os.Create(path)
+		switch f, err := os.OpenFile(filepath.Join(dir, fmt.Sprintf("%s%03d%s", prefix, index, suffix)), os.O_RDWR|os.O_CREATE|os.O_EXCL, 0666); {
+		case err == nil:
+			return f, nil
+		case !os.IsExist(err):
+			return nil, err
 		}
 	}
 	// Give up
@@ -44,11 +46,15 @@ func deferDeleteTempFile(path string) {
 }
 
 // cleanupTempFiles removes any temporary files selected for deferred cleaning.
-func cleanupTempFiles() {
+func cleanupTempFiles() error {
 	tempFilesMu.Lock()
+	defer tempFilesMu.Unlock()
+	var lastErr error
 	for _, f := range tempFiles {
-		os.Remove(f)
+		if err := os.Remove(f); err != nil {
+			lastErr = err
+		}
 	}
 	tempFiles = nil
-	tempFilesMu.Unlock()
+	return lastErr
 }
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/webhtml.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/webhtml.go
index 89b8882a6b..4f7610c7e5 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/webhtml.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/webhtml.go
@@ -166,6 +166,73 @@ a {
   color: gray;
   pointer-events: none;
 }
+.menu-check-mark {
+  position: absolute;
+  left: 2px;
+}
+.menu-delete-btn {
+  position: absolute;
+  right: 2px;
+}
+
+{{/* Used to disable events when a modal dialog is displayed */}}
+#dialog-overlay {
+  display: none;
+  position: fixed;
+  left: 0px;
+  top: 0px;
+  width: 100%;
+  height: 100%;
+  background-color: rgba(1,1,1,0.1);
+}
+
+.dialog {
+  {{/* Displayed centered horizontally near the top */}}
+  display: none;
+  position: fixed;
+  margin: 0px;
+  top: 60px;
+  left: 50%;
+  transform: translateX(-50%);
+
+  z-index: 3;
+  font-size: 125%;
+  background-color: #ffffff;
+  box-shadow: 0 1px 5px rgba(0,0,0,.3);
+}
+.dialog-header {
+  font-size: 120%;
+  border-bottom: 1px solid #CCCCCC;
+  width: 100%;
+  text-align: center;
+  background: #EEEEEE;
+  user-select: none;
+}
+.dialog-footer {
+  border-top: 1px solid #CCCCCC;
+  width: 100%;
+  text-align: right;
+  padding: 10px;
+}
+.dialog-error {
+  margin: 10px;
+  color: red;
+}
+.dialog input {
+  margin: 10px;
+  font-size: inherit;
+}
+.dialog button {
+  margin-left: 10px;
+  font-size: inherit;
+}
+#save-dialog, #delete-dialog {
+  width: 50%;
+  max-width: 20em;
+}
+#delete-prompt {
+  padding: 10px;
+}
 
 #content {
   overflow-y: scroll;
@@ -200,6 +267,8 @@ table thead {
   font-family: 'Roboto Medium', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
 }
 table tr th {
+  position: sticky;
+  top: 0;
   background-color: #ddd;
   text-align: right;
   padding: .3em .5em;
@@ -282,6 +351,24 @@ table tr td {
     </div>
   </div>
 
+  <div id="config" class="menu-item">
+    <div class="menu-name">
+      Config
+      <i class="downArrow"></i>
+    </div>
+    <div class="submenu">
+      <a title="{{.Help.save_config}}" id="save-config">Save as ...</a>
+      <hr>
+      {{range .Configs}}
+        <a href="{{.URL}}">
+          {{if .Current}}<span class="menu-check-mark">✓</span>{{end}}
+          {{.Name}}
+          {{if .UserConfig}}<span class="menu-delete-btn" data-config={{.Name}}>🗙</span>{{end}}
+        </a>
+      {{end}}
+    </div>
+  </div>
+
   <div>
     <input id="search" type="text" placeholder="Search regexp" autocomplete="off" autocapitalize="none" size=40>
   </div>
@@ -294,6 +381,31 @@ table tr td {
   </div>
 </div>
 
+<div id="dialog-overlay"></div>
+
+<div class="dialog" id="save-dialog">
+  <div class="dialog-header">Save options as</div>
+  <datalist id="config-list">
+    {{range .Configs}}{{if .UserConfig}}<option value="{{.Name}}" />{{end}}{{end}}
+  </datalist>
+  <input id="save-name" type="text" list="config-list" placeholder="New config" />
+  <div class="dialog-footer">
+    <span class="dialog-error" id="save-error"></span>
+    <button id="save-cancel">Cancel</button>
+    <button id="save-confirm">Save</button>
+  </div>
+</div>
+
+<div class="dialog" id="delete-dialog">
+  <div class="dialog-header" id="delete-dialog-title">Delete config</div>
+  <div id="delete-prompt"></div>
+  <div class="dialog-footer">
+    <span class="dialog-error" id="delete-error"></span>
+    <button id="delete-cancel">Cancel</button>
+    <button id="delete-confirm">Delete</button>
+  </div>
+</div>
+
 <div id="errors">{{range .Errors}}<div>{{.}}</div>{{end}}</div>
 {{end}}
 
@@ -583,6 +695,131 @@ function initMenus() {
   }, { passive: true, capture: true });
 }
 
+function sendURL(method, url, done) {
+  fetch(url.toString(), {method: method})
+      .then((response) => { done(response.ok); })
+      .catch((error) => { done(false); });
+}
+
+// Initialize handlers for saving/loading configurations.
+function initConfigManager() {
+  'use strict';
+
+  // Initialize various elements.
+  function elem(id) {
+    const result = document.getElementById(id);
+    if (!result) console.warn('element ' + id + ' not found');
+    return result;
+  }
+  const overlay = elem('dialog-overlay');
+  const saveDialog = elem('save-dialog');
+  const saveInput = elem('save-name');
+  const saveError = elem('save-error');
+  const delDialog = elem('delete-dialog');
+  const delPrompt = elem('delete-prompt');
+  const delError = elem('delete-error');
+
+  let currentDialog = null;
+  let currentDeleteTarget = null;
+
+  function showDialog(dialog) {
+    if (currentDialog != null) {
+      overlay.style.display = 'none';
+      currentDialog.style.display = 'none';
+    }
+    currentDialog = dialog;
+    if (dialog != null) {
+      overlay.style.display = 'block';
+      dialog.style.display = 'block';
+    }
+  }
+
+  function cancelDialog(e) {
+    showDialog(null);
+  }
+
+  // Show dialog for saving the current config.
+  function showSaveDialog(e) {
+    saveError.innerText = '';
+    showDialog(saveDialog);
+    saveInput.focus();
+  }
+
+  // Commit save config.
+  function commitSave(e) {
+    const name = saveInput.value;
+    const url = new URL(document.URL);
+    // Set path relative to existing path.
+    url.pathname = new URL('./saveconfig', document.URL).pathname;
+    url.searchParams.set('config', name);
+    saveError.innerText = '';
+    sendURL('POST', url, (ok) => {
+      if (!ok) {
+        saveError.innerText = 'Save failed';
+      } else {
+        showDialog(null);
+        location.reload();  // Reload to show updated config menu
+      }
+    });
+  }
+
+  function handleSaveInputKey(e) {
+    if (e.key === 'Enter') commitSave(e);
+  }
+
+  function deleteConfig(e, elem) {
+    e.preventDefault();
+    const config = elem.dataset.config;
+    delPrompt.innerText = 'Delete ' + config + '?';
+    currentDeleteTarget = elem;
+    showDialog(delDialog);
+  }
+
+  function commitDelete(e, elem) {
+    if (!currentDeleteTarget) return;
+    const config = currentDeleteTarget.dataset.config;
+    const url = new URL('./deleteconfig', document.URL);
+    url.searchParams.set('config', config);
+    delError.innerText = '';
+    sendURL('DELETE', url, (ok) => {
+      if (!ok) {
+        delError.innerText = 'Delete failed';
+        return;
+      }
+      showDialog(null);
+      // Remove menu entry for this config.
+      if (currentDeleteTarget && currentDeleteTarget.parentElement) {
+        currentDeleteTarget.parentElement.remove();
+      }
+    });
+  }
+
+  // Bind event on elem to fn.
+  function bind(event, elem, fn) {
+    if (elem == null) return;
+    elem.addEventListener(event, fn);
+    if (event == 'click') {
+      // Also enable via touch.
+      elem.addEventListener('touchstart', fn);
+    }
+  }
+
+  bind('click', elem('save-config'), showSaveDialog);
+  bind('click', elem('save-cancel'), cancelDialog);
+  bind('click', elem('save-confirm'), commitSave);
+  bind('keydown', saveInput, handleSaveInputKey);
+
+  bind('click', elem('delete-cancel'), cancelDialog);
+  bind('click', elem('delete-confirm'), commitDelete);
+
+  // Activate deletion button for all config entries in menu.
+  for (const del of Array.from(document.getElementsByClassName('menu-delete-btn'))) {
+    bind('click', del, (e) => {
+      deleteConfig(e, del);
+    });
+  }
+}
+
 function viewer(baseUrl, nodes) {
   'use strict';
 
@@ -875,6 +1112,7 @@ function viewer(baseUrl, nodes) {
   }
 
   addAction('details', handleDetails);
+  initConfigManager();
 
   search.addEventListener('input', handleSearch);
   search.addEventListener('keydown', handleKey);
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/driver/webui.go b/src/cmd/vendor/github.com/google/pprof/internal/driver/webui.go
index 4006085538..52dc68809c 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/driver/webui.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/driver/webui.go
@@ -35,22 +35,28 @@ import (
 
 // webInterface holds the state needed for serving a browser based interface.
 type webInterface struct {
-	prof      *profile.Profile
-	options   *plugin.Options
-	help      map[string]string
-	templates *template.Template
+	prof         *profile.Profile
+	options      *plugin.Options
+	help         map[string]string
+	templates    *template.Template
+	settingsFile string
 }
 
-func makeWebInterface(p *profile.Profile, opt *plugin.Options) *webInterface {
+func makeWebInterface(p *profile.Profile, opt *plugin.Options) (*webInterface, error) {
+	settingsFile, err := settingsFileName()
+	if err != nil {
+		return nil, err
+	}
 	templates := template.New("templategroup")
 	addTemplates(templates)
 	report.AddSourceTemplates(templates)
 	return &webInterface{
-		prof:      p,
-		options:   opt,
-		help:      make(map[string]string),
-		templates: templates,
-	}
+		prof:         p,
+		options:      opt,
+		help:         make(map[string]string),
+		templates:    templates,
+		settingsFile: settingsFile,
+	}, nil
 }
 
 // maxEntries is the maximum number of entries to print for text interfaces.
@@ -80,6 +86,7 @@ type webArgs struct {
 	TextBody    string
 	Top         []report.TextItem
 	FlameGraph  template.JS
+	Configs     []configMenuEntry
 }
 
 func serveWebInterface(hostport string, p *profile.Profile, o *plugin.Options, disableBrowser bool) error {
@@ -88,16 +95,20 @@ func serveWebInterface(hostport string, p *profile.Profile, o *plugin.Options, d
 		return err
 	}
 	interactiveMode = true
-	ui := makeWebInterface(p, o)
+	ui, err := makeWebInterface(p, o)
+	if err != nil {
+		return err
+	}
 	for n, c := range pprofCommands {
 		ui.help[n] = c.description
 	}
-	for n, v := range pprofVariables {
-		ui.help[n] = v.help
+	for n, help := range configHelp {
+		ui.help[n] = help
 	}
 	ui.help["details"] = "Show information about the profile and this view"
 	ui.help["graph"] = "Display profile as a directed graph"
 	ui.help["reset"] = "Show the entire profile"
+	ui.help["save_config"] = "Save current settings"
 
 	server := o.HTTPServer
 	if server == nil {
@@ -108,12 +119,14 @@ func serveWebInterface(hostport string, p *profile.Profile, o *plugin.Options, d
 		Host:     host,
 		Port:     port,
 		Handlers: map[string]http.Handler{
-			"/":           http.HandlerFunc(ui.dot),
-			"/top":        http.HandlerFunc(ui.top),
-			"/disasm":     http.HandlerFunc(ui.disasm),
-			"/source":     http.HandlerFunc(ui.source),
-			"/peek":       http.HandlerFunc(ui.peek),
-			"/flamegraph": http.HandlerFunc(ui.flamegraph),
+			"/":             http.HandlerFunc(ui.dot),
+			"/top":          http.HandlerFunc(ui.top),
+			"/disasm":       http.HandlerFunc(ui.disasm),
+			"/source":       http.HandlerFunc(ui.source),
+			"/peek":         http.HandlerFunc(ui.peek),
+			"/flamegraph":   http.HandlerFunc(ui.flamegraph),
+			"/saveconfig":   http.HandlerFunc(ui.saveConfig),
+			"/deleteconfig": http.HandlerFunc(ui.deleteConfig),
 		},
 	}
 
@@ -206,21 +219,9 @@ func isLocalhost(host string) bool {
 
 func openBrowser(url string, o *plugin.Options) {
 	// Construct URL.
-	u, _ := gourl.Parse(url)
-	q := u.Query()
-	for _, p := range []struct{ param, key string }{
-		{"f", "focus"},
-		{"s", "show"},
-		{"sf", "show_from"},
-		{"i", "ignore"},
-		{"h", "hide"},
-		{"si", "sample_index"},
-	} {
-		if v := pprofVariables[p.key].value; v != "" {
-			q.Set(p.param, v)
-		}
-	}
-	u.RawQuery = q.Encode()
+	baseURL, _ := gourl.Parse(url)
+	current := currentConfig()
+	u, _ := current.makeURL(*baseURL)
 
 	// Give server a little time to get ready.
 	time.Sleep(time.Millisecond * 500)
@@ -240,28 +241,23 @@ func openBrowser(url string, o *plugin.Options) {
 	o.UI.PrintErr(u.String())
 }
 
-func varsFromURL(u *gourl.URL) variables {
-	vars := pprofVariables.makeCopy()
-	vars["focus"].value = u.Query().Get("f")
-	vars["show"].value = u.Query().Get("s")
-	vars["show_from"].value = u.Query().Get("sf")
-	vars["ignore"].value = u.Query().Get("i")
-	vars["hide"].value = u.Query().Get("h")
-	vars["sample_index"].value = u.Query().Get("si")
-	return vars
-}
-
 // makeReport generates a report for the specified command.
+// If configEditor is not null, it is used to edit the config used for the report.
 func (ui *webInterface) makeReport(w http.ResponseWriter, req *http.Request,
-	cmd []string, vars ...string) (*report.Report, []string) {
-	v := varsFromURL(req.URL)
-	for i := 0; i+1 < len(vars); i += 2 {
-		v[vars[i]].value = vars[i+1]
+	cmd []string, configEditor func(*config)) (*report.Report, []string) {
+	cfg := currentConfig()
+	if err := cfg.applyURL(req.URL.Query()); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		ui.options.UI.PrintErr(err)
+		return nil, nil
+	}
+	if configEditor != nil {
+		configEditor(&cfg)
 	}
 	catcher := &errorCatcher{UI: ui.options.UI}
 	options := *ui.options
 	options.UI = catcher
-	_, rpt, err := generateRawReport(ui.prof, cmd, v, &options)
+	_, rpt, err := generateRawReport(ui.prof, cmd, cfg, &options)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		ui.options.UI.PrintErr(err)
@@ -271,7 +267,7 @@ func (ui *webInterface) makeReport(w http.ResponseWriter, req *http.Request,
 }
 
 // render generates html using the named template based on the contents of data.
-func (ui *webInterface) render(w http.ResponseWriter, tmpl string,
+func (ui *webInterface) render(w http.ResponseWriter, req *http.Request, tmpl string,
 	rpt *report.Report, errList, legend []string, data webArgs) {
 	file := getFromLegend(legend, "File: ", "unknown")
 	profile := getFromLegend(legend, "Type: ", "unknown")
@@ -281,6 +277,8 @@ func (ui *webInterface) render(w http.ResponseWriter, tmpl string,
 	data.SampleTypes = sampleTypes(ui.prof)
 	data.Legend = legend
 	data.Help = ui.help
+	data.Configs = configMenu(ui.settingsFile, *req.URL)
+
 	html := &bytes.Buffer{}
 	if err := ui.templates.ExecuteTemplate(html, tmpl, data); err != nil {
 		http.Error(w, "internal template error", http.StatusInternalServerError)
@@ -293,7 +291,7 @@ func (ui *webInterface) render(w http.ResponseWriter, tmpl string,
 
 // dot generates a web page containing an svg diagram.
 func (ui *webInterface) dot(w http.ResponseWriter, req *http.Request) {
-	rpt, errList := ui.makeReport(w, req, []string{"svg"})
+	rpt, errList := ui.makeReport(w, req, []string{"svg"}, nil)
 	if rpt == nil {
 		return // error already reported
 	}
@@ -320,7 +318,7 @@ func (ui *webInterface) dot(w http.ResponseWriter, req *http.Request) {
 		nodes = append(nodes, n.Info.Name)
 	}
 
-	ui.render(w, "graph", rpt, errList, legend, webArgs{
+	ui.render(w, req, "graph", rpt, errList, legend, webArgs{
 		HTMLBody: template.HTML(string(svg)),
 		Nodes:    nodes,
 	})
@@ -345,7 +343,9 @@ func dotToSvg(dot []byte) ([]byte, error) {
 }
 
 func (ui *webInterface) top(w http.ResponseWriter, req *http.Request) {
-	rpt, errList := ui.makeReport(w, req, []string{"top"}, "nodecount", "500")
+	rpt, errList := ui.makeReport(w, req, []string{"top"}, func(cfg *config) {
+		cfg.NodeCount = 500
+	})
 	if rpt == nil {
 		return // error already reported
 	}
@@ -355,7 +355,7 @@ func (ui *webInterface) top(w http.ResponseWriter, req *http.Request) {
 		nodes = append(nodes, item.Name)
 	}
 
-	ui.render(w, "top", rpt, errList, legend, webArgs{
+	ui.render(w, req, "top", rpt, errList, legend, webArgs{
 		Top:   top,
 		Nodes: nodes,
 	})
@@ -364,7 +364,7 @@ func (ui *webInterface) top(w http.ResponseWriter, req *http.Request) {
 // disasm generates a web page containing disassembly.
 func (ui *webInterface) disasm(w http.ResponseWriter, req *http.Request) {
 	args := []string{"disasm", req.URL.Query().Get("f")}
-	rpt, errList := ui.makeReport(w, req, args)
+	rpt, errList := ui.makeReport(w, req, args, nil)
 	if rpt == nil {
 		return // error already reported
 	}
@@ -377,7 +377,7 @@ func (ui *webInterface) disasm(w http.ResponseWriter, req *http.Request) {
 	}
 
 	legend := report.ProfileLabels(rpt)
-	ui.render(w, "plaintext", rpt, errList, legend, webArgs{
+	ui.render(w, req, "plaintext", rpt, errList, legend, webArgs{
 		TextBody: out.String(),
 	})
 
@@ -387,7 +387,7 @@ func (ui *webInterface) disasm(w http.ResponseWriter, req *http.Request) {
 // data.
 func (ui *webInterface) source(w http.ResponseWriter, req *http.Request) {
 	args := []string{"weblist", req.URL.Query().Get("f")}
-	rpt, errList := ui.makeReport(w, req, args)
+	rpt, errList := ui.makeReport(w, req, args, nil)
 	if rpt == nil {
 		return // error already reported
 	}
@@ -401,7 +401,7 @@ func (ui *webInterface) source(w http.ResponseWriter, req *http.Request) {
 	}
 
 	legend := report.ProfileLabels(rpt)
-	ui.render(w, "sourcelisting", rpt, errList, legend, webArgs{
+	ui.render(w, req, "sourcelisting", rpt, errList, legend, webArgs{
 		HTMLBody: template.HTML(body.String()),
 	})
 }
@@ -409,7 +409,9 @@ func (ui *webInterface) source(w http.ResponseWriter, req *http.Request) {
 // peek generates a web page listing callers/callers.
 func (ui *webInterface) peek(w http.ResponseWriter, req *http.Request) {
 	args := []string{"peek", req.URL.Query().Get("f")}
-	rpt, errList := ui.makeReport(w, req, args, "lines", "t")
+	rpt, errList := ui.makeReport(w, req, args, func(cfg *config) {
+		cfg.Granularity = "lines"
+	})
 	if rpt == nil {
 		return // error already reported
 	}
@@ -422,11 +424,30 @@ func (ui *webInterface) peek(w http.ResponseWriter, req *http.Request) {
 	}
 
 	legend := report.ProfileLabels(rpt)
-	ui.render(w, "plaintext", rpt, errList, legend, webArgs{
+	ui.render(w, req, "plaintext", rpt, errList, legend, webArgs{
 		TextBody: out.String(),
 	})
 }
 
+// saveConfig saves URL configuration.
+func (ui *webInterface) saveConfig(w http.ResponseWriter, req *http.Request) {
+	if err := setConfig(ui.settingsFile, *req.URL); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		ui.options.UI.PrintErr(err)
+		return
+	}
+}
+
+// deleteConfig deletes a configuration.
+func (ui *webInterface) deleteConfig(w http.ResponseWriter, req *http.Request) {
+	name := req.URL.Query().Get("config")
+	if err := removeConfig(ui.settingsFile, name); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		ui.options.UI.PrintErr(err)
+		return
+	}
+}
+
 // getFromLegend returns the suffix of an entry in legend that starts
 // with param.  It returns def if no such entry is found.
 func getFromLegend(legend []string, param, def string) string {
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 09debfb007..8cb87da9af 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
@@ -127,7 +127,7 @@ func (b *builder) addLegend() {
 	}
 	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`))
+	fmt.Fprintf(b, ` label="%s\l"`, strings.Join(escapeAllForDot(labels), `\l`))
 	if b.config.LegendURL != "" {
 		fmt.Fprintf(b, ` URL="%s" target="_blank"`, b.config.LegendURL)
 	}
@@ -187,7 +187,7 @@ func (b *builder) addNode(node *Node, nodeID int, maxFlat float64) {
 
 	// Create DOT attribute for node.
 	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,
+		label, nodeID, fontSize, shape, escapeForDot(node.Info.PrintableName()), cumValue,
 		dotColor(float64(node.CumValue())/float64(abs64(b.config.Total)), false),
 		dotColor(float64(node.CumValue())/float64(abs64(b.config.Total)), true))
 
@@ -305,7 +305,8 @@ func (b *builder) addEdge(edge *Edge, from, to int, hasNodelets bool) {
 		arrow = "..."
 	}
 	tooltip := fmt.Sprintf(`"%s %s %s (%s)"`,
-		edge.Src.Info.PrintableName(), arrow, edge.Dest.Info.PrintableName(), w)
+		escapeForDot(edge.Src.Info.PrintableName()), arrow,
+		escapeForDot(edge.Dest.Info.PrintableName()), w)
 	attr = fmt.Sprintf(`%s tooltip=%s labeltooltip=%s`, attr, tooltip, tooltip)
 
 	if edge.Residual {
@@ -382,7 +383,7 @@ func dotColor(score float64, isBackground bool) string {
 
 func multilinePrintableName(info *NodeInfo) string {
 	infoCopy := *info
-	infoCopy.Name = ShortenFunctionName(infoCopy.Name)
+	infoCopy.Name = escapeForDot(ShortenFunctionName(infoCopy.Name))
 	infoCopy.Name = strings.Replace(infoCopy.Name, "::", `\n`, -1)
 	infoCopy.Name = strings.Replace(infoCopy.Name, ".", `\n`, -1)
 	if infoCopy.File != "" {
@@ -472,3 +473,19 @@ func min64(a, b int64) int64 {
 	}
 	return b
 }
+
+// escapeAllForDot applies escapeForDot to all strings in the given slice.
+func escapeAllForDot(in []string) []string {
+	var out = make([]string, len(in))
+	for i := range in {
+		out[i] = escapeForDot(in[i])
+	}
+	return out
+}
+
+// escapeForDot escapes double quotes and backslashes, and replaces Graphviz's
+// "center" character (\n) with a left-justified character.
+// See https://graphviz.org/doc/info/attrs.html#k:escString for more info.
+func escapeForDot(str string) string {
+	return strings.ReplaceAll(strings.ReplaceAll(strings.ReplaceAll(str, `\`, `\\`), `"`, `\"`), "\n", `\l`)
+}
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 d2397a93d8..74b904c402 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
@@ -28,12 +28,14 @@ import (
 )
 
 var (
-	// Removes package name and method arugments for Java method names.
+	// Removes package name and method arguments for Java method names.
 	// See tests for examples.
 	javaRegExp = regexp.MustCompile(`^(?:[a-z]\w*\.)*([A-Z][\w\$]*\.(?:<init>|[a-z][\w\$]*(?:\$\d+)?))(?:(?:\()|$)`)
-	// Removes package name and method arugments for Go function names.
+	// Removes package name and method arguments for Go function names.
 	// See tests for examples.
 	goRegExp = regexp.MustCompile(`^(?:[\w\-\.]+\/)+(.+)`)
+	// Removes potential module versions in a package path.
+	goVerRegExp = regexp.MustCompile(`^(.*?)/v(?:[2-9]|[1-9][0-9]+)([./].*)$`)
 	// Strips C++ namespace prefix from a C++ function / method name.
 	// NOTE: Make sure to keep the template parameters in the name. Normally,
 	// template parameters are stripped from the C++ names but when
@@ -317,6 +319,8 @@ func New(prof *profile.Profile, o *Options) *Graph {
 // nodes.
 func newGraph(prof *profile.Profile, o *Options) (*Graph, map[uint64]Nodes) {
 	nodes, locationMap := CreateNodes(prof, o)
+	seenNode := make(map[*Node]bool)
+	seenEdge := make(map[nodePair]bool)
 	for _, sample := range prof.Sample {
 		var w, dw int64
 		w = o.SampleValue(sample.Value)
@@ -326,8 +330,12 @@ func newGraph(prof *profile.Profile, o *Options) (*Graph, map[uint64]Nodes) {
 		if dw == 0 && w == 0 {
 			continue
 		}
-		seenNode := make(map[*Node]bool, len(sample.Location))
-		seenEdge := make(map[nodePair]bool, len(sample.Location))
+		for k := range seenNode {
+			delete(seenNode, k)
+		}
+		for k := range seenEdge {
+			delete(seenEdge, k)
+		}
 		var parent *Node
 		// A residual edge goes over one or more nodes that were not kept.
 		residual := false
@@ -440,6 +448,7 @@ func newTree(prof *profile.Profile, o *Options) (g *Graph) {
 // ShortenFunctionName returns a shortened version of a function's name.
 func ShortenFunctionName(f string) string {
 	f = cppAnonymousPrefixRegExp.ReplaceAllString(f, "")
+	f = goVerRegExp.ReplaceAllString(f, `${1}${2}`)
 	for _, re := range []*regexp.Regexp{goRegExp, javaRegExp, cppRegExp} {
 		if matches := re.FindStringSubmatch(f); len(matches) >= 2 {
 			return strings.Join(matches[1:], "")
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/plugin/plugin.go b/src/cmd/vendor/github.com/google/pprof/internal/plugin/plugin.go
index 4c1db2331f..3a8d0af730 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/plugin/plugin.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/plugin/plugin.go
@@ -114,7 +114,7 @@ type ObjTool interface {
 
 	// Disasm disassembles the named object file, starting at
 	// the start address and stopping at (before) the end address.
-	Disasm(file string, start, end uint64) ([]Inst, error)
+	Disasm(file string, start, end uint64, intelSyntax bool) ([]Inst, error)
 }
 
 // An Inst is a single instruction in an assembly listing.
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/report/report.go b/src/cmd/vendor/github.com/google/pprof/internal/report/report.go
index 56083d8abf..bc5685d61e 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/report/report.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/report/report.go
@@ -79,6 +79,8 @@ type Options struct {
 	Symbol     *regexp.Regexp // Symbols to include on disassembly report.
 	SourcePath string         // Search path for source files.
 	TrimPath   string         // Paths to trim from source file paths.
+
+	IntelSyntax bool // Whether or not to print assembly in Intel syntax.
 }
 
 // Generate generates a report as directed by the Report.
@@ -438,7 +440,7 @@ func PrintAssembly(w io.Writer, rpt *Report, obj plugin.ObjTool, maxFuncs int) e
 		flatSum, cumSum := sns.Sum()
 
 		// Get the function assembly.
-		insts, err := obj.Disasm(s.sym.File, s.sym.Start, s.sym.End)
+		insts, err := obj.Disasm(s.sym.File, s.sym.Start, s.sym.End, o.IntelSyntax)
 		if err != nil {
 			return err
 		}
@@ -1201,6 +1203,13 @@ func reportLabels(rpt *Report, g *graph.Graph, origCount, droppedNodes, droppedE
 				nodeCount, origCount))
 		}
 	}
+
+	// Help new users understand the graph.
+	// A new line is intentionally added here to better show this message.
+	if fullHeaders {
+		label = append(label, "\nSee https://git.io/JfYMW for how to read the graph")
+	}
+
 	return label
 }
 
diff --git a/src/cmd/vendor/github.com/google/pprof/internal/report/source.go b/src/cmd/vendor/github.com/google/pprof/internal/report/source.go
index ab8b64cbab..b480535439 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/report/source.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/report/source.go
@@ -205,7 +205,7 @@ func PrintWebList(w io.Writer, rpt *Report, obj plugin.ObjTool, maxFiles int) er
 		ff := fileFunction{n.Info.File, n.Info.Name}
 		fns := fileNodes[ff]
 
-		asm := assemblyPerSourceLine(symbols, fns, ff.fileName, obj)
+		asm := assemblyPerSourceLine(symbols, fns, ff.fileName, obj, o.IntelSyntax)
 		start, end := sourceCoordinates(asm)
 
 		fnodes, path, err := getSourceFromFile(ff.fileName, reader, fns, start, end)
@@ -239,7 +239,7 @@ func sourceCoordinates(asm map[int][]assemblyInstruction) (start, end int) {
 // assemblyPerSourceLine disassembles the binary containing a symbol
 // and classifies the assembly instructions according to its
 // corresponding source line, annotating them with a set of samples.
-func assemblyPerSourceLine(objSyms []*objSymbol, rs graph.Nodes, src string, obj plugin.ObjTool) map[int][]assemblyInstruction {
+func assemblyPerSourceLine(objSyms []*objSymbol, rs graph.Nodes, src string, obj plugin.ObjTool, intelSyntax bool) map[int][]assemblyInstruction {
 	assembly := make(map[int][]assemblyInstruction)
 	// Identify symbol to use for this collection of samples.
 	o := findMatchingSymbol(objSyms, rs)
@@ -248,7 +248,7 @@ func assemblyPerSourceLine(objSyms []*objSymbol, rs graph.Nodes, src string, obj
 	}
 
 	// Extract assembly for matched symbol
-	insts, err := obj.Disasm(o.sym.File, o.sym.Start, o.sym.End)
+	insts, err := obj.Disasm(o.sym.File, o.sym.Start, o.sym.End, intelSyntax)
 	if err != nil {
 		return assembly
 	}
diff --git a/src/cmd/vendor/github.com/google/pprof/profile/profile.go b/src/cmd/vendor/github.com/google/pprof/profile/profile.go
index c950d8dc7f..d94d8b3d1c 100644
--- a/src/cmd/vendor/github.com/google/pprof/profile/profile.go
+++ b/src/cmd/vendor/github.com/google/pprof/profile/profile.go
@@ -398,10 +398,12 @@ func (p *Profile) CheckValid() error {
 			}
 		}
 		for _, ln := range l.Line {
-			if f := ln.Function; f != nil {
-				if f.ID == 0 || functions[f.ID] != f {
-					return fmt.Errorf("inconsistent function %p: %d", f, f.ID)
-				}
+			f := ln.Function
+			if f == nil {
+				return fmt.Errorf("location id: %d has a line with nil function", l.ID)
+			}
+			if f.ID == 0 || functions[f.ID] != f {
+				return fmt.Errorf("inconsistent function %p: %d", f, f.ID)
 			}
 		}
 	}
diff --git a/src/cmd/vendor/github.com/ianlancetaylor/demangle/ast.go b/src/cmd/vendor/github.com/ianlancetaylor/demangle/ast.go
index 0ad5354f58..ccbe5b3559 100644
--- a/src/cmd/vendor/github.com/ianlancetaylor/demangle/ast.go
+++ b/src/cmd/vendor/github.com/ianlancetaylor/demangle/ast.go
@@ -5,7 +5,6 @@
 package demangle
 
 import (
-	"bytes"
 	"fmt"
 	"strings"
 )
@@ -23,7 +22,10 @@ type AST interface {
 	// Copy an AST with possible transformations.
 	// If the skip function returns true, no copy is required.
 	// If the copy function returns nil, no copy is required.
-	// Otherwise the AST returned by copy is used in a copy of the full AST.
+	// The Copy method will do the right thing if copy returns nil
+	// for some components of an AST but not others, so a good
+	// copy function will only return non-nil for AST values that
+	// need to change.
 	// Copy itself returns either a copy or nil.
 	Copy(copy func(AST) AST, skip func(AST) bool) AST
 
@@ -51,7 +53,7 @@ func ASTToString(a AST, options ...Option) string {
 type printState struct {
 	tparams bool // whether to print template parameters
 
-	buf  bytes.Buffer
+	buf  strings.Builder
 	last byte // Last byte written to buffer.
 
 	// The inner field is a list of items to print for a type
@@ -398,13 +400,172 @@ func (tp *TemplateParam) goString(indent int, field string) string {
 	return fmt.Sprintf("%*s%sTemplateParam: Template: %p; Index %d", indent, "", field, tp.Template, tp.Index)
 }
 
+// LambdaAuto is a lambda auto parameter.
+type LambdaAuto struct {
+	Index int
+}
+
+func (la *LambdaAuto) print(ps *printState) {
+	// We print the index plus 1 because that is what the standard
+	// demangler does.
+	fmt.Fprintf(&ps.buf, "auto:%d", la.Index+1)
+}
+
+func (la *LambdaAuto) Traverse(fn func(AST) bool) {
+	fn(la)
+}
+
+func (la *LambdaAuto) Copy(fn func(AST) AST, skip func(AST) bool) AST {
+	if skip(la) {
+		return nil
+	}
+	return fn(la)
+}
+
+func (la *LambdaAuto) GoString() string {
+	return la.goString(0, "")
+}
+
+func (la *LambdaAuto) goString(indent int, field string) string {
+	return fmt.Sprintf("%*s%sLambdaAuto: Index %d", indent, "", field, la.Index)
+}
+
 // Qualifiers is an ordered list of type qualifiers.
-type Qualifiers []string
+type Qualifiers struct {
+	Qualifiers []AST
+}
+
+func (qs *Qualifiers) print(ps *printState) {
+	first := true
+	for _, q := range qs.Qualifiers {
+		if !first {
+			ps.writeByte(' ')
+		}
+		q.print(ps)
+		first = false
+	}
+}
+
+func (qs *Qualifiers) Traverse(fn func(AST) bool) {
+	if fn(qs) {
+		for _, q := range qs.Qualifiers {
+			q.Traverse(fn)
+		}
+	}
+}
+
+func (qs *Qualifiers) Copy(fn func(AST) AST, skip func(AST) bool) AST {
+	if skip(qs) {
+		return nil
+	}
+	changed := false
+	qualifiers := make([]AST, len(qs.Qualifiers))
+	for i, q := range qs.Qualifiers {
+		qc := q.Copy(fn, skip)
+		if qc == nil {
+			qualifiers[i] = q
+		} else {
+			qualifiers[i] = qc
+			changed = true
+		}
+	}
+	if !changed {
+		return fn(qs)
+	}
+	qs = &Qualifiers{Qualifiers: qualifiers}
+	if r := fn(qs); r != nil {
+		return r
+	}
+	return qs
+}
+
+func (qs *Qualifiers) GoString() string {
+	return qs.goString(0, "")
+}
+
+func (qs *Qualifiers) goString(indent int, field string) string {
+	quals := fmt.Sprintf("%*s%s", indent, "", field)
+	for _, q := range qs.Qualifiers {
+		quals += "\n"
+		quals += q.goString(indent+2, "")
+	}
+	return quals
+}
+
+// Qualifier is a single type qualifier.
+type Qualifier struct {
+	Name  string // qualifier name: const, volatile, etc.
+	Exprs []AST  // can be non-nil for noexcept and throw
+}
+
+func (q *Qualifier) print(ps *printState) {
+	ps.writeString(q.Name)
+	if len(q.Exprs) > 0 {
+		ps.writeByte('(')
+		first := true
+		for _, e := range q.Exprs {
+			if !first {
+				ps.writeString(", ")
+			}
+			ps.print(e)
+			first = false
+		}
+		ps.writeByte(')')
+	}
+}
+
+func (q *Qualifier) Traverse(fn func(AST) bool) {
+	if fn(q) {
+		for _, e := range q.Exprs {
+			e.Traverse(fn)
+		}
+	}
+}
+
+func (q *Qualifier) Copy(fn func(AST) AST, skip func(AST) bool) AST {
+	if skip(q) {
+		return nil
+	}
+	exprs := make([]AST, len(q.Exprs))
+	changed := false
+	for i, e := range q.Exprs {
+		ec := e.Copy(fn, skip)
+		if ec == nil {
+			exprs[i] = e
+		} else {
+			exprs[i] = ec
+			changed = true
+		}
+	}
+	if !changed {
+		return fn(q)
+	}
+	q = &Qualifier{Name: q.Name, Exprs: exprs}
+	if r := fn(q); r != nil {
+		return r
+	}
+	return q
+}
+
+func (q *Qualifier) GoString() string {
+	return q.goString(0, "Qualifier: ")
+}
+
+func (q *Qualifier) goString(indent int, field string) string {
+	qs := fmt.Sprintf("%*s%s%s", indent, "", field, q.Name)
+	if len(q.Exprs) > 0 {
+		for i, e := range q.Exprs {
+			qs += "\n"
+			qs += e.goString(indent+2, fmt.Sprintf("%d: ", i))
+		}
+	}
+	return qs
+}
 
 // TypeWithQualifiers is a type with standard qualifiers.
 type TypeWithQualifiers struct {
 	Base       AST
-	Qualifiers Qualifiers
+	Qualifiers AST
 }
 
 func (twq *TypeWithQualifiers) print(ps *printState) {
@@ -414,7 +575,7 @@ func (twq *TypeWithQualifiers) print(ps *printState) {
 	if len(ps.inner) > 0 {
 		// The qualifier wasn't printed by Base.
 		ps.writeByte(' ')
-		ps.writeString(strings.Join(twq.Qualifiers, " "))
+		ps.print(twq.Qualifiers)
 		ps.inner = ps.inner[:len(ps.inner)-1]
 	}
 }
@@ -422,7 +583,7 @@ func (twq *TypeWithQualifiers) print(ps *printState) {
 // Print qualifiers as an inner type by just printing the qualifiers.
 func (twq *TypeWithQualifiers) printInner(ps *printState) {
 	ps.writeByte(' ')
-	ps.writeString(strings.Join(twq.Qualifiers, " "))
+	ps.print(twq.Qualifiers)
 }
 
 func (twq *TypeWithQualifiers) Traverse(fn func(AST) bool) {
@@ -436,10 +597,17 @@ func (twq *TypeWithQualifiers) Copy(fn func(AST) AST, skip func(AST) bool) AST {
 		return nil
 	}
 	base := twq.Base.Copy(fn, skip)
-	if base == nil {
+	quals := twq.Qualifiers.Copy(fn, skip)
+	if base == nil && quals == nil {
 		return fn(twq)
 	}
-	twq = &TypeWithQualifiers{Base: base, Qualifiers: twq.Qualifiers}
+	if base == nil {
+		base = twq.Base
+	}
+	if quals == nil {
+		quals = twq.Qualifiers
+	}
+	twq = &TypeWithQualifiers{Base: base, Qualifiers: quals}
 	if r := fn(twq); r != nil {
 		return r
 	}
@@ -451,14 +619,15 @@ func (twq *TypeWithQualifiers) GoString() string {
 }
 
 func (twq *TypeWithQualifiers) goString(indent int, field string) string {
-	return fmt.Sprintf("%*s%sTypeWithQualifiers: Qualifiers: %s\n%s", indent, "", field,
-		twq.Qualifiers, twq.Base.goString(indent+2, "Base: "))
+	return fmt.Sprintf("%*s%sTypeWithQualifiers:\n%s\n%s", indent, "", field,
+		twq.Qualifiers.goString(indent+2, "Qualifiers: "),
+		twq.Base.goString(indent+2, "Base: "))
 }
 
 // MethodWithQualifiers is a method with qualifiers.
 type MethodWithQualifiers struct {
 	Method       AST
-	Qualifiers   Qualifiers
+	Qualifiers   AST
 	RefQualifier string // "" or "&" or "&&"
 }
 
@@ -467,9 +636,9 @@ func (mwq *MethodWithQualifiers) print(ps *printState) {
 	ps.inner = append(ps.inner, mwq)
 	ps.print(mwq.Method)
 	if len(ps.inner) > 0 {
-		if len(mwq.Qualifiers) > 0 {
+		if mwq.Qualifiers != nil {
 			ps.writeByte(' ')
-			ps.writeString(strings.Join(mwq.Qualifiers, " "))
+			ps.print(mwq.Qualifiers)
 		}
 		if mwq.RefQualifier != "" {
 			ps.writeByte(' ')
@@ -480,9 +649,9 @@ func (mwq *MethodWithQualifiers) print(ps *printState) {
 }
 
 func (mwq *MethodWithQualifiers) printInner(ps *printState) {
-	if len(mwq.Qualifiers) > 0 {
+	if mwq.Qualifiers != nil {
 		ps.writeByte(' ')
-		ps.writeString(strings.Join(mwq.Qualifiers, " "))
+		ps.print(mwq.Qualifiers)
 	}
 	if mwq.RefQualifier != "" {
 		ps.writeByte(' ')
@@ -501,10 +670,20 @@ func (mwq *MethodWithQualifiers) Copy(fn func(AST) AST, skip func(AST) bool) AST
 		return nil
 	}
 	method := mwq.Method.Copy(fn, skip)
-	if method == nil {
+	var quals AST
+	if mwq.Qualifiers != nil {
+		quals = mwq.Qualifiers.Copy(fn, skip)
+	}
+	if method == nil && quals == nil {
 		return fn(mwq)
 	}
-	mwq = &MethodWithQualifiers{Method: method, Qualifiers: mwq.Qualifiers, RefQualifier: mwq.RefQualifier}
+	if method == nil {
+		method = mwq.Method
+	}
+	if quals == nil {
+		quals = mwq.Qualifiers
+	}
+	mwq = &MethodWithQualifiers{Method: method, Qualifiers: quals, RefQualifier: mwq.RefQualifier}
 	if r := fn(mwq); r != nil {
 		return r
 	}
@@ -517,14 +696,14 @@ func (mwq *MethodWithQualifiers) GoString() string {
 
 func (mwq *MethodWithQualifiers) goString(indent int, field string) string {
 	var q string
-	if len(mwq.Qualifiers) > 0 {
-		q += fmt.Sprintf(" Qualifiers: %v", mwq.Qualifiers)
+	if mwq.Qualifiers != nil {
+		q += "\n" + mwq.Qualifiers.goString(indent+2, "Qualifiers: ")
 	}
 	if mwq.RefQualifier != "" {
 		if q != "" {
-			q += ";"
+			q += "\n"
 		}
-		q += " RefQualifier: " + mwq.RefQualifier
+		q += fmt.Sprintf("%*s%s%s", indent+2, "", "RefQualifier: ", mwq.RefQualifier)
 	}
 	return fmt.Sprintf("%*s%sMethodWithQualifiers:%s\n%s", indent, "", field,
 		q, mwq.Method.goString(indent+2, "Method: "))
@@ -1955,6 +2134,22 @@ func (u *Unary) goString(indent int, field string) string {
 		u.Expr.goString(indent+2, "Expr: "))
 }
 
+// isDesignatedInitializer reports whether x is a designated
+// initializer.
+func isDesignatedInitializer(x AST) bool {
+	switch x := x.(type) {
+	case *Binary:
+		if op, ok := x.Op.(*Operator); ok {
+			return op.Name == "=" || op.Name == "]="
+		}
+	case *Trinary:
+		if op, ok := x.Op.(*Operator); ok {
+			return op.Name == "[...]="
+		}
+	}
+	return false
+}
+
 // Binary is a binary operation in an expression.
 type Binary struct {
 	Op    AST
@@ -1975,6 +2170,27 @@ func (b *Binary) print(ps *printState) {
 		return
 	}
 
+	if isDesignatedInitializer(b) {
+		if op.Name == "=" {
+			ps.writeByte('.')
+		} else {
+			ps.writeByte('[')
+		}
+		ps.print(b.Left)
+		if op.Name == "]=" {
+			ps.writeByte(']')
+		}
+		if isDesignatedInitializer(b.Right) {
+			// Don't add anything between designated
+			// initializer chains.
+			ps.print(b.Right)
+		} else {
+			ps.writeByte('=')
+			parenthesize(ps, b.Right)
+		}
+		return
+	}
+
 	// Use an extra set of parentheses around an expression that
 	// uses the greater-than operator, so that it does not get
 	// confused with the '>' that ends template parameters.
@@ -1984,15 +2200,28 @@ func (b *Binary) print(ps *printState) {
 
 	left := b.Left
 
-	// A function call in an expression should not print the types
-	// of the arguments.
+	// For a function call in an expression, don't print the types
+	// of the arguments unless there is a return type.
+	skipParens := false
 	if op != nil && op.Name == "()" {
 		if ty, ok := b.Left.(*Typed); ok {
-			left = ty.Name
+			if ft, ok := ty.Type.(*FunctionType); ok {
+				if ft.Return == nil {
+					left = ty.Name
+				} else {
+					skipParens = true
+				}
+			} else {
+				left = ty.Name
+			}
 		}
 	}
 
-	parenthesize(ps, left)
+	if skipParens {
+		ps.print(left)
+	} else {
+		parenthesize(ps, left)
+	}
 
 	if op != nil && op.Name == "[]" {
 		ps.writeByte('[')
@@ -2070,6 +2299,23 @@ type Trinary struct {
 }
 
 func (t *Trinary) print(ps *printState) {
+	if isDesignatedInitializer(t) {
+		ps.writeByte('[')
+		ps.print(t.First)
+		ps.writeString(" ... ")
+		ps.print(t.Second)
+		ps.writeByte(']')
+		if isDesignatedInitializer(t.Third) {
+			// Don't add anything between designated
+			// initializer chains.
+			ps.print(t.Third)
+		} else {
+			ps.writeByte('=')
+			parenthesize(ps, t.Third)
+		}
+		return
+	}
+
 	parenthesize(ps, t.First)
 	ps.writeByte('?')
 	parenthesize(ps, t.Second)
@@ -2362,6 +2608,9 @@ func (l *Literal) print(ps *printState) {
 				ps.writeString("true")
 				return
 			}
+		} else if b.Name == "decltype(nullptr)" && l.Val == "" {
+			ps.print(l.Type)
+			return
 		} else {
 			isFloat = builtinTypeFloat[b.Name]
 		}
@@ -2821,6 +3070,83 @@ func (s *Special2) goString(indent int, field string) string {
 		indent+2, "", s.Middle, s.Val2.goString(indent+2, "Val2: "))
 }
 
+// EnableIf is used by clang for an enable_if attribute.
+type EnableIf struct {
+	Type AST
+	Args []AST
+}
+
+func (ei *EnableIf) print(ps *printState) {
+	ps.print(ei.Type)
+	ps.writeString(" [enable_if:")
+	first := true
+	for _, a := range ei.Args {
+		if !first {
+			ps.writeString(", ")
+		}
+		ps.print(a)
+		first = false
+	}
+	ps.writeString("]")
+}
+
+func (ei *EnableIf) Traverse(fn func(AST) bool) {
+	if fn(ei) {
+		ei.Type.Traverse(fn)
+		for _, a := range ei.Args {
+			a.Traverse(fn)
+		}
+	}
+}
+
+func (ei *EnableIf) Copy(fn func(AST) AST, skip func(AST) bool) AST {
+	if skip(ei) {
+		return nil
+	}
+	typ := ei.Type.Copy(fn, skip)
+	argsChanged := false
+	args := make([]AST, len(ei.Args))
+	for i, a := range ei.Args {
+		ac := a.Copy(fn, skip)
+		if ac == nil {
+			args[i] = a
+		} else {
+			args[i] = ac
+			argsChanged = true
+		}
+	}
+	if typ == nil && !argsChanged {
+		return fn(ei)
+	}
+	if typ == nil {
+		typ = ei.Type
+	}
+	ei = &EnableIf{Type: typ, Args: args}
+	if r := fn(ei); r != nil {
+		return r
+	}
+	return ei
+}
+
+func (ei *EnableIf) GoString() string {
+	return ei.goString(0, "")
+}
+
+func (ei *EnableIf) goString(indent int, field string) string {
+	var args string
+	if len(ei.Args) == 0 {
+		args = fmt.Sprintf("%*sArgs: nil", indent+2, "")
+	} else {
+		args = fmt.Sprintf("%*sArgs:", indent+2, "")
+		for i, a := range ei.Args {
+			args += "\n"
+			args += a.goString(indent+4, fmt.Sprintf("%d: ", i))
+		}
+	}
+	return fmt.Sprintf("%*s%sEnableIf:\n%s\n%s", indent, "", field,
+		ei.Type.goString(indent+2, "Type: "), args)
+}
+
 // Print the inner types.
 func (ps *printState) printInner(prefixOnly bool) []AST {
 	var save []AST
diff --git a/src/cmd/vendor/github.com/ianlancetaylor/demangle/demangle.go b/src/cmd/vendor/github.com/ianlancetaylor/demangle/demangle.go
index 7541b736ba..c2667446df 100644
--- a/src/cmd/vendor/github.com/ianlancetaylor/demangle/demangle.go
+++ b/src/cmd/vendor/github.com/ianlancetaylor/demangle/demangle.go
@@ -5,6 +5,8 @@
 // Package demangle defines functions that demangle GCC/LLVM C++ symbol names.
 // This package recognizes names that were mangled according to the C++ ABI
 // defined at http://codesourcery.com/cxx-abi/.
+//
+// Most programs will want to call Filter or ToString.
 package demangle
 
 import (
@@ -45,7 +47,7 @@ func Filter(name string, options ...Option) string {
 	return ret
 }
 
-// ToString demangles a C++ symbol name, returning human-readable C++
+// ToString demangles a C++ symbol name, returning a human-readable C++
 // name or an error.
 // If the name does not appear to be a C++ symbol name at all, the
 // error will be ErrNotMangledName.
@@ -183,6 +185,7 @@ type state struct {
 	off       int           // offset of str within original string
 	subs      substitutions // substitutions
 	templates []*Template   // templates being processed
+	inLambda  int           // number of lambdas being parsed
 }
 
 // copy returns a copy of the current state.
@@ -310,15 +313,42 @@ func (st *state) encoding(params bool, local forLocalNameType) AST {
 	if mwq != nil {
 		check = mwq.Method
 	}
-	template, _ := check.(*Template)
+
+	var template *Template
+	switch check := check.(type) {
+	case *Template:
+		template = check
+	case *Qualified:
+		if check.LocalName {
+			n := check.Name
+			if nmwq, ok := n.(*MethodWithQualifiers); ok {
+				n = nmwq.Method
+			}
+			template, _ = n.(*Template)
+		}
+	}
+	var oldInLambda int
 	if template != nil {
 		st.templates = append(st.templates, template)
+		oldInLambda = st.inLambda
+		st.inLambda = 0
+	}
+
+	// Checking for the enable_if attribute here is what the LLVM
+	// demangler does.  This is not very general but perhaps it is
+	// sufficent.
+	const enableIfPrefix = "Ua9enable_ifI"
+	var enableIfArgs []AST
+	if strings.HasPrefix(st.str, enableIfPrefix) {
+		st.advance(len(enableIfPrefix) - 1)
+		enableIfArgs = st.templateArgs()
 	}
 
 	ft := st.bareFunctionType(hasReturnType(a))
 
 	if template != nil {
 		st.templates = st.templates[:len(st.templates)-1]
+		st.inLambda = oldInLambda
 	}
 
 	ft = simplify(ft)
@@ -349,13 +379,24 @@ func (st *state) encoding(params bool, local forLocalNameType) AST {
 		}
 	}
 
-	return &Typed{Name: a, Type: ft}
+	r := AST(&Typed{Name: a, Type: ft})
+
+	if len(enableIfArgs) > 0 {
+		r = &EnableIf{Type: r, Args: enableIfArgs}
+	}
+
+	return r
 }
 
 // hasReturnType returns whether the mangled form of a will have a
 // return type.
 func hasReturnType(a AST) bool {
 	switch a := a.(type) {
+	case *Qualified:
+		if a.LocalName {
+			return hasReturnType(a.Name)
+		}
+		return false
 	case *Template:
 		return !isCDtorConversion(a.Name)
 	case *TypeWithQualifiers:
@@ -481,7 +522,7 @@ func (st *state) nestedName() AST {
 	q := st.cvQualifiers()
 	r := st.refQualifier()
 	a := st.prefix()
-	if len(q) > 0 || r != "" {
+	if q != nil || r != "" {
 		a = &MethodWithQualifiers{Method: a, Qualifiers: q, RefQualifier: r}
 	}
 	if len(st.str) == 0 || st.str[0] != 'E' {
@@ -608,6 +649,29 @@ func (st *state) prefix() AST {
 				// gives appropriate output.
 				st.advance(1)
 				continue
+			case 'J':
+				// It appears that in some cases clang
+				// can emit a J for a template arg
+				// without the expected I.  I don't
+				// know when this happens, but I've
+				// seen it in some large C++ programs.
+				if a == nil {
+					st.fail("unexpected template arguments")
+				}
+				var args []AST
+				for len(st.str) == 0 || st.str[0] != 'E' {
+					arg := st.templateArg()
+					args = append(args, arg)
+				}
+				st.advance(1)
+				tmpl := &Template{Name: a, Args: args}
+				if isCast {
+					st.setTemplate(a, tmpl)
+					st.clearTemplateArgs(args)
+					isCast = false
+				}
+				a = nil
+				next = tmpl
 			default:
 				st.fail("unrecognized letter in prefix")
 			}
@@ -754,19 +818,26 @@ var operators = map[string]operator{
 	"ad": {"&", 1},
 	"an": {"&", 2},
 	"at": {"alignof ", 1},
+	"aw": {"co_await ", 1},
 	"az": {"alignof ", 1},
 	"cc": {"const_cast", 2},
 	"cl": {"()", 2},
+	// cp is not in the ABI but is used by clang "when the call
+	// would use ADL except for being parenthesized."
+	"cp": {"()", 2},
 	"cm": {",", 2},
 	"co": {"~", 1},
 	"dV": {"/=", 2},
+	"dX": {"[...]=", 3},
 	"da": {"delete[] ", 1},
 	"dc": {"dynamic_cast", 2},
 	"de": {"*", 1},
+	"di": {"=", 2},
 	"dl": {"delete ", 1},
 	"ds": {".*", 2},
 	"dt": {".", 2},
 	"dv": {"/", 2},
+	"dx": {"]=", 2},
 	"eO": {"^=", 2},
 	"eo": {"^", 2},
 	"eq": {"==", 2},
@@ -808,7 +879,10 @@ var operators = map[string]operator{
 	"rc": {"reinterpret_cast", 2},
 	"rm": {"%", 2},
 	"rs": {">>", 2},
+	"sP": {"sizeof...", 1},
+	"sZ": {"sizeof...", 1},
 	"sc": {"static_cast", 2},
+	"ss": {"<=>", 2},
 	"st": {"sizeof ", 1},
 	"sz": {"sizeof ", 1},
 	"tr": {"throw", 0},
@@ -928,6 +1002,7 @@ func (st *state) javaResource() AST {
 //                ::= TT <type>
 //                ::= TI <type>
 //                ::= TS <type>
+//                ::= TA <template-arg>
 //                ::= GV <(object) name>
 //                ::= T <call-offset> <(base) encoding>
 //                ::= Tc <call-offset> <call-offset> <(base) encoding>
@@ -961,6 +1036,9 @@ func (st *state) specialName() AST {
 		case 'S':
 			t := st.demangleType(false)
 			return &Special{Prefix: "typeinfo name for ", Val: t}
+		case 'A':
+			t := st.templateArg()
+			return &Special{Prefix: "template parameter object for ", Val: t}
 		case 'h':
 			st.callOffset('h')
 			v := st.encoding(true, notForLocalName)
@@ -1138,7 +1216,7 @@ func (st *state) demangleType(isCast bool) AST {
 	addSubst := true
 
 	q := st.cvQualifiers()
-	if len(q) > 0 {
+	if q != nil {
 		if len(st.str) == 0 {
 			st.fail("expected type")
 		}
@@ -1159,7 +1237,7 @@ func (st *state) demangleType(isCast bool) AST {
 	if btype, ok := builtinTypes[st.str[0]]; ok {
 		ret = &BuiltinType{Name: btype}
 		st.advance(1)
-		if len(q) > 0 {
+		if q != nil {
 			ret = &TypeWithQualifiers{Base: ret, Qualifiers: q}
 			st.subs.add(ret)
 		}
@@ -1286,6 +1364,8 @@ func (st *state) demangleType(isCast bool) AST {
 
 		case 'a':
 			ret = &Name{Name: "auto"}
+		case 'c':
+			ret = &Name{Name: "decltype(auto)"}
 
 		case 'f':
 			ret = &BuiltinType{Name: "decimal32"}
@@ -1295,6 +1375,8 @@ func (st *state) demangleType(isCast bool) AST {
 			ret = &BuiltinType{Name: "decimal128"}
 		case 'h':
 			ret = &BuiltinType{Name: "half"}
+		case 'u':
+			ret = &BuiltinType{Name: "char8_t"}
 		case 's':
 			ret = &BuiltinType{Name: "char16_t"}
 		case 'i':
@@ -1343,7 +1425,7 @@ func (st *state) demangleType(isCast bool) AST {
 		}
 	}
 
-	if len(q) > 0 {
+	if q != nil {
 		if _, ok := ret.(*FunctionType); ok {
 			ret = &MethodWithQualifiers{Method: ret, Qualifiers: q, RefQualifier: ""}
 		} else if mwq, ok := ret.(*MethodWithQualifiers); ok {
@@ -1433,17 +1515,32 @@ func (st *state) demangleCastTemplateArgs(tp AST, addSubst bool) AST {
 }
 
 // mergeQualifiers merges two qualifer lists into one.
-func mergeQualifiers(q1, q2 Qualifiers) Qualifiers {
+func mergeQualifiers(q1AST, q2AST AST) AST {
+	if q1AST == nil {
+		return q2AST
+	}
+	if q2AST == nil {
+		return q1AST
+	}
+	q1 := q1AST.(*Qualifiers)
 	m := make(map[string]bool)
-	for _, qual := range q1 {
-		m[qual] = true
+	for _, qualAST := range q1.Qualifiers {
+		qual := qualAST.(*Qualifier)
+		if len(qual.Exprs) == 0 {
+			m[qual.Name] = true
+		}
 	}
-	for _, qual := range q2 {
-		if !m[qual] {
-			q1 = append(q1, qual)
-			m[qual] = true
+	rq := q1.Qualifiers
+	for _, qualAST := range q2AST.(*Qualifiers).Qualifiers {
+		qual := qualAST.(*Qualifier)
+		if len(qual.Exprs) > 0 {
+			rq = append(rq, qualAST)
+		} else if !m[qual.Name] {
+			rq = append(rq, qualAST)
+			m[qual.Name] = true
 		}
 	}
+	q1.Qualifiers = rq
 	return q1
 }
 
@@ -1456,20 +1553,51 @@ var qualifiers = map[byte]string{
 }
 
 // <CV-qualifiers> ::= [r] [V] [K]
-func (st *state) cvQualifiers() Qualifiers {
-	var q Qualifiers
+func (st *state) cvQualifiers() AST {
+	var q []AST
+qualLoop:
 	for len(st.str) > 0 {
 		if qv, ok := qualifiers[st.str[0]]; ok {
-			q = append([]string{qv}, q...)
+			qual := &Qualifier{Name: qv}
+			q = append([]AST{qual}, q...)
 			st.advance(1)
-		} else if len(st.str) > 1 && st.str[:2] == "Dx" {
-			q = append([]string{"transaction_safe"}, q...)
-			st.advance(2)
+		} else if len(st.str) > 1 && st.str[0] == 'D' {
+			var qual AST
+			switch st.str[1] {
+			case 'x':
+				qual = &Qualifier{Name: "transaction_safe"}
+				st.advance(2)
+			case 'o':
+				qual = &Qualifier{Name: "noexcept"}
+				st.advance(2)
+			case 'O':
+				st.advance(2)
+				expr := st.expression()
+				if len(st.str) == 0 || st.str[0] != 'E' {
+					st.fail("expected E after computed noexcept expression")
+				}
+				st.advance(1)
+				qual = &Qualifier{Name: "noexcept", Exprs: []AST{expr}}
+			case 'w':
+				st.advance(2)
+				parmlist := st.parmlist()
+				if len(st.str) == 0 || st.str[0] != 'E' {
+					st.fail("expected E after throw parameter list")
+				}
+				st.advance(1)
+				qual = &Qualifier{Name: "throw", Exprs: parmlist}
+			default:
+				break qualLoop
+			}
+			q = append([]AST{qual}, q...)
 		} else {
 			break
 		}
 	}
-	return q
+	if len(q) == 0 {
+		return nil
+	}
+	return &Qualifiers{Qualifiers: q}
 }
 
 // <ref-qualifier> ::= R
@@ -1677,7 +1805,7 @@ func (st *state) compactNumber() int {
 // whatever the template parameter would be expanded to here.  We sort
 // this out in substitution and simplify.
 func (st *state) templateParam() AST {
-	if len(st.templates) == 0 {
+	if len(st.templates) == 0 && st.inLambda == 0 {
 		st.fail("template parameter not in scope of template")
 	}
 	off := st.off
@@ -1685,6 +1813,13 @@ func (st *state) templateParam() AST {
 	st.checkChar('T')
 	n := st.compactNumber()
 
+	if st.inLambda > 0 {
+		// g++ mangles lambda auto params as template params.
+		// Apparently we can't encounter a template within a lambda.
+		// See https://gcc.gnu.org/PR78252.
+		return &LambdaAuto{Index: n}
+	}
+
 	template := st.templates[len(st.templates)-1]
 
 	if template == nil {
@@ -1723,6 +1858,10 @@ func (st *state) setTemplate(a AST, tmpl *Template) {
 			}
 			a.Template = tmpl
 			return false
+		case *Closure:
+			// There are no template params in closure types.
+			// https://gcc.gnu.org/PR78252.
+			return false
 		default:
 			for _, v := range seen {
 				if v == a {
@@ -1812,12 +1951,60 @@ func (st *state) exprList(stop byte) AST {
 // <expression> ::= <(unary) operator-name> <expression>
 //              ::= <(binary) operator-name> <expression> <expression>
 //              ::= <(trinary) operator-name> <expression> <expression> <expression>
+//              ::= pp_ <expression>
+//              ::= mm_ <expression>
+//              ::= cl <expression>+ E
 //              ::= cl <expression>+ E
+//              ::= cv <type> <expression>
+//              ::= cv <type> _ <expression>* E
+//              ::= tl <type> <braced-expression>* E
+//              ::= il <braced-expression>* E
+//              ::= [gs] nw <expression>* _ <type> E
+//              ::= [gs] nw <expression>* _ <type> <initializer>
+//              ::= [gs] na <expression>* _ <type> E
+//              ::= [gs] na <expression>* _ <type> <initializer>
+//              ::= [gs] dl <expression>
+//              ::= [gs] da <expression>
+//              ::= dc <type> <expression>
+//              ::= sc <type> <expression>
+//              ::= cc <type> <expression>
+//              ::= rc <type> <expression>
+//              ::= ti <type>
+//              ::= te <expression>
 //              ::= st <type>
+//              ::= sz <expression>
+//              ::= at <type>
+//              ::= az <expression>
+//              ::= nx <expression>
 //              ::= <template-param>
-//              ::= sr <type> <unqualified-name>
-//              ::= sr <type> <unqualified-name> <template-args>
+//              ::= <function-param>
+//              ::= dt <expression> <unresolved-name>
+//              ::= pt <expression> <unresolved-name>
+//              ::= ds <expression> <expression>
+//              ::= sZ <template-param>
+//              ::= sZ <function-param>
+//              ::= sP <template-arg>* E
+//              ::= sp <expression>
+//              ::= fl <binary operator-name> <expression>
+//              ::= fr <binary operator-name> <expression>
+//              ::= fL <binary operator-name> <expression> <expression>
+//              ::= fR <binary operator-name> <expression> <expression>
+//              ::= tw <expression>
+//              ::= tr
+//              ::= <unresolved-name>
 //              ::= <expr-primary>
+//
+// <function-param> ::= fp <CV-qualifiers> _
+//                  ::= fp <CV-qualifiers> <number>
+//                  ::= fL <number> p <CV-qualifiers> _
+//                  ::= fL <number> p <CV-qualifiers> <number>
+//                  ::= fpT
+//
+// <braced-expression> ::= <expression>
+//                     ::= di <field source-name> <braced-expression>
+//                     ::= dx <index expression> <braced-expression>
+//                     ::= dX <range begin expression> <range end expression> <braced-expression>
+//
 func (st *state) expression() AST {
 	if len(st.str) == 0 {
 		st.fail("expected expression")
@@ -1827,61 +2014,7 @@ func (st *state) expression() AST {
 	} else if st.str[0] == 'T' {
 		return st.templateParam()
 	} else if st.str[0] == 's' && len(st.str) > 1 && st.str[1] == 'r' {
-		st.advance(2)
-		if len(st.str) == 0 {
-			st.fail("expected unresolved type")
-		}
-		switch st.str[0] {
-		case 'T', 'D', 'S':
-			t := st.demangleType(false)
-			n := st.baseUnresolvedName()
-			n = &Qualified{Scope: t, Name: n, LocalName: false}
-			if len(st.str) > 0 && st.str[0] == 'I' {
-				args := st.templateArgs()
-				n = &Template{Name: n, Args: args}
-			}
-			return n
-		default:
-			var s AST
-			if st.str[0] == 'N' {
-				st.advance(1)
-				s = st.demangleType(false)
-			}
-			for len(st.str) == 0 || st.str[0] != 'E' {
-				// GCC does not seem to follow the ABI here.
-				// It can emit type/name without an 'E'.
-				if s != nil && len(st.str) > 0 && !isDigit(st.str[0]) {
-					if q, ok := s.(*Qualified); ok {
-						a := q.Scope
-						if t, ok := a.(*Template); ok {
-							st.subs.add(t.Name)
-							st.subs.add(t)
-						} else {
-							st.subs.add(a)
-						}
-						return s
-					}
-				}
-				n := st.sourceName()
-				if len(st.str) > 0 && st.str[0] == 'I' {
-					st.subs.add(n)
-					args := st.templateArgs()
-					n = &Template{Name: n, Args: args}
-				}
-				if s == nil {
-					s = n
-				} else {
-					s = &Qualified{Scope: s, Name: n, LocalName: false}
-				}
-				st.subs.add(s)
-			}
-			if s == nil {
-				st.fail("missing scope in unresolved name")
-			}
-			st.advance(1)
-			n := st.baseUnresolvedName()
-			return &Qualified{Scope: s, Name: n, LocalName: false}
-		}
+		return st.unresolvedName()
 	} else if st.str[0] == 's' && len(st.str) > 1 && st.str[1] == 'p' {
 		st.advance(2)
 		e := st.expression()
@@ -1911,9 +2044,25 @@ func (st *state) expression() AST {
 			st.advance(1)
 			return &FunctionParam{Index: 0}
 		} else {
+			// We can see qualifiers here, but we don't
+			// include them in the demangled string.
+			st.cvQualifiers()
 			index := st.compactNumber()
 			return &FunctionParam{Index: index + 1}
 		}
+	} else if st.str[0] == 'f' && len(st.str) > 2 && st.str[1] == 'L' && isDigit(st.str[2]) {
+		st.advance(2)
+		// We don't include the scope count in the demangled string.
+		st.number()
+		if len(st.str) == 0 || st.str[0] != 'p' {
+			st.fail("expected p after function parameter scope count")
+		}
+		st.advance(1)
+		// We can see qualifiers here, but we don't include them
+		// in the demangled string.
+		st.cvQualifiers()
+		index := st.compactNumber()
+		return &FunctionParam{Index: index + 1}
 	} else if isDigit(st.str[0]) || (st.str[0] == 'o' && len(st.str) > 1 && st.str[1] == 'n') {
 		if st.str[0] == 'o' {
 			// Skip operator function ID.
@@ -1975,13 +2124,15 @@ func (st *state) expression() AST {
 				left, _ = st.operatorName(true)
 				right = st.expression()
 				return &Fold{Left: code[1] == 'l', Op: left, Arg1: right, Arg2: nil}
+			} else if code == "di" {
+				left, _ = st.unqualifiedName()
 			} else {
 				left = st.expression()
 			}
-			if code == "cl" {
+			if code == "cl" || code == "cp" {
 				right = st.exprList('E')
 			} else if code == "dt" || code == "pt" {
-				right, _ = st.unqualifiedName()
+				right = st.unresolvedName()
 				if len(st.str) > 0 && st.str[0] == 'I' {
 					args := st.templateArgs()
 					right = &Template{Name: right, Args: args}
@@ -2034,6 +2185,82 @@ func (st *state) expression() AST {
 	}
 }
 
+// <unresolved-name> ::= [gs] <base-unresolved-name>
+//                   ::= sr <unresolved-type> <base-unresolved-name>
+//                   ::= srN <unresolved-type> <unresolved-qualifier-level>+ E <base-unresolved-name>
+//                   ::= [gs] sr <unresolved-qualifier-level>+ E <base-unresolved-name>
+func (st *state) unresolvedName() AST {
+	if len(st.str) >= 2 && st.str[:2] == "gs" {
+		st.advance(2)
+		n := st.unresolvedName()
+		return &Unary{
+			Op:         &Operator{Name: "::"},
+			Expr:       n,
+			Suffix:     false,
+			SizeofType: false,
+		}
+	} else if len(st.str) >= 2 && st.str[:2] == "sr" {
+		st.advance(2)
+		if len(st.str) == 0 {
+			st.fail("expected unresolved type")
+		}
+		switch st.str[0] {
+		case 'T', 'D', 'S':
+			t := st.demangleType(false)
+			n := st.baseUnresolvedName()
+			n = &Qualified{Scope: t, Name: n, LocalName: false}
+			if len(st.str) > 0 && st.str[0] == 'I' {
+				args := st.templateArgs()
+				n = &Template{Name: n, Args: args}
+				st.subs.add(n)
+			}
+			return n
+		default:
+			var s AST
+			if st.str[0] == 'N' {
+				st.advance(1)
+				s = st.demangleType(false)
+			}
+			for len(st.str) == 0 || st.str[0] != 'E' {
+				// GCC does not seem to follow the ABI here.
+				// It can emit type/name without an 'E'.
+				if s != nil && len(st.str) > 0 && !isDigit(st.str[0]) {
+					if q, ok := s.(*Qualified); ok {
+						a := q.Scope
+						if t, ok := a.(*Template); ok {
+							st.subs.add(t.Name)
+							st.subs.add(t)
+						} else {
+							st.subs.add(a)
+						}
+						return s
+					}
+				}
+				n := st.sourceName()
+				if len(st.str) > 0 && st.str[0] == 'I' {
+					st.subs.add(n)
+					args := st.templateArgs()
+					n = &Template{Name: n, Args: args}
+				}
+				if s == nil {
+					s = n
+				} else {
+					s = &Qualified{Scope: s, Name: n, LocalName: false}
+				}
+				st.subs.add(s)
+			}
+			if s == nil {
+				st.fail("missing scope in unresolved name")
+			}
+			st.advance(1)
+			n := st.baseUnresolvedName()
+			return &Qualified{Scope: s, Name: n, LocalName: false}
+		}
+	} else {
+		return st.baseUnresolvedName()
+	}
+}
+
 // <base-unresolved-name> ::= <simple-id>
 //                        ::= on <operator-name>
 //                        ::= on <operator-name> <template-args>
@@ -2099,7 +2326,14 @@ func (st *state) exprPrimary() AST {
 			st.advance(1)
 		}
 		if len(st.str) > 0 && st.str[0] == 'E' {
-			st.fail("missing literal value")
+			if bt, ok := t.(*BuiltinType); ok && bt.Name == "decltype(nullptr)" {
+				// A nullptr should not have a value.
+				// We accept one if present because GCC
+				// used to generate one.
+				// https://gcc.gnu.org/PR91979.
+			} else {
+				st.fail("missing literal value")
+			}
 		}
 		i := 0
 		for len(st.str) > i && st.str[i] != 'E' {
@@ -2116,17 +2350,29 @@ func (st *state) exprPrimary() AST {
 	return ret
 }
 
-// <discriminator> ::= _ <(non-negative) number>
+// <discriminator> ::= _ <(non-negative) number> (when number < 10)
+//                     __ <(non-negative) number> _ (when number >= 10)
 func (st *state) discriminator(a AST) AST {
 	if len(st.str) == 0 || st.str[0] != '_' {
 		return a
 	}
 	off := st.off
 	st.advance(1)
+	trailingUnderscore := false
+	if len(st.str) > 0 && st.str[0] == '_' {
+		st.advance(1)
+		trailingUnderscore = true
+	}
 	d := st.number()
 	if d < 0 {
 		st.failEarlier("invalid negative discriminator", st.off-off)
 	}
+	if trailingUnderscore && d >= 10 {
+		if len(st.str) == 0 || st.str[0] != '_' {
+			st.fail("expected _ after discriminator >= 10")
+		}
+		st.advance(1)
+	}
 	// We don't currently print out the discriminator, so we don't
 	// save it.
 	return a
@@ -2136,15 +2382,15 @@ func (st *state) discriminator(a AST) AST {
 func (st *state) closureTypeName() AST {
 	st.checkChar('U')
 	st.checkChar('l')
+	st.inLambda++
 	types := st.parmlist()
+	st.inLambda--
 	if len(st.str) == 0 || st.str[0] != 'E' {
 		st.fail("expected E after closure type name")
 	}
 	st.advance(1)
 	num := st.compactNumber()
-	ret := &Closure{Types: types, Num: num}
-	st.subs.add(ret)
-	return ret
+	return &Closure{Types: types, Num: num}
 }
 
 // <unnamed-type-name> ::= Ut [ <nonnegative number> ] _
@@ -2295,31 +2541,92 @@ func (st *state) substitution(forPrefix bool) AST {
 		// We need to update any references to template
 		// parameters to refer to the currently active
 		// template.
+
+		// When copying a Typed we may need to adjust
+		// the templates.
+		copyTemplates := st.templates
+		var oldInLambda []int
+
+		// pushTemplate is called from skip, popTemplate from copy.
+		pushTemplate := func(template *Template) {
+			copyTemplates = append(copyTemplates, template)
+			oldInLambda = append(oldInLambda, st.inLambda)
+			st.inLambda = 0
+		}
+		popTemplate := func() {
+			copyTemplates = copyTemplates[:len(copyTemplates)-1]
+			st.inLambda = oldInLambda[len(oldInLambda)-1]
+			oldInLambda = oldInLambda[:len(oldInLambda)-1]
+		}
+
 		copy := func(a AST) AST {
-			tp, ok := a.(*TemplateParam)
-			if !ok {
+			var index int
+			switch a := a.(type) {
+			case *Typed:
+				// Remove the template added in skip.
+				if _, ok := a.Name.(*Template); ok {
+					popTemplate()
+				}
+				return nil
+			case *Closure:
+				// Undo the decrement in skip.
+				st.inLambda--
 				return nil
+			case *TemplateParam:
+				index = a.Index
+			case *LambdaAuto:
+				// A lambda auto parameter is represented
+				// as a template parameter, so we may have
+				// to change back when substituting.
+				index = a.Index
+			default:
+				return nil
+			}
+			if st.inLambda > 0 {
+				if _, ok := a.(*LambdaAuto); ok {
+					return nil
+				}
+				return &LambdaAuto{Index: index}
 			}
-			if len(st.templates) == 0 {
+			var template *Template
+			if len(copyTemplates) > 0 {
+				template = copyTemplates[len(copyTemplates)-1]
+			} else if rt, ok := ret.(*Template); ok {
+				// At least with clang we can see a template
+				// to start, and sometimes we need to refer
+				// to it. There is probably something wrong
+				// here.
+				template = rt
+			} else {
 				st.failEarlier("substituted template parameter not in scope of template", dec)
 			}
-			template := st.templates[len(st.templates)-1]
 			if template == nil {
 				// This template parameter is within
 				// the scope of a cast operator.
-				return &TemplateParam{Index: tp.Index, Template: nil}
+				return &TemplateParam{Index: index, Template: nil}
 			}
 
-			if tp.Index >= len(template.Args) {
-				st.failEarlier(fmt.Sprintf("substituted template index out of range (%d >= %d)", tp.Index, len(template.Args)), dec)
+			if index >= len(template.Args) {
+				st.failEarlier(fmt.Sprintf("substituted template index out of range (%d >= %d)", index, len(template.Args)), dec)
 			}
 
-			return &TemplateParam{Index: tp.Index, Template: template}
+			return &TemplateParam{Index: index, Template: template}
 		}
 		var seen []AST
 		skip := func(a AST) bool {
-			if _, ok := a.(*Typed); ok {
-				return true
+			switch a := a.(type) {
+			case *Typed:
+				if template, ok := a.Name.(*Template); ok {
+					// This template is removed in copy.
+					pushTemplate(template)
+				}
+				return false
+			case *Closure:
+				// This is decremented in copy.
+				st.inLambda++
+				return false
+			case *TemplateParam, *LambdaAuto:
+				return false
 			}
 			for _, v := range seen {
 				if v == a {
@@ -2329,6 +2636,7 @@ func (st *state) substitution(forPrefix bool) AST {
 			seen = append(seen, a)
 			return false
 		}
+
 		if c := ret.Copy(copy, skip); c != nil {
 			return c
 		}
@@ -2351,6 +2659,7 @@ func (st *state) substitution(forPrefix bool) AST {
 
 		if len(st.str) > 0 && st.str[0] == 'B' {
 			a = st.taggedName(a)
+			st.subs.add(a)
 		}
 
 		return a