proc,service,terminal: propagate g.startpc

Adds StartPC to proc.G, StartLoc to api.Goroutine and show the start
location in the command line client when appropriate.

Updates #1104

Documentation/cli/README.md

@@ -203,13 +203,14 @@ Called with more arguments it will execute a command on the specified goroutine.
 ## goroutines
 List program goroutines.
 
-	goroutines [-u (default: user location)|-r (runtime location)|-g (go statement location) ] [ -t (stack trace)]
+	goroutines [-u (default: user location)|-r (runtime location)|-g (go statement location)|-s (start location)] [ -t (stack trace)]
 
 Print out info for every goroutine. The flag controls what information is shown along with each goroutine:
 
 	-u	displays location of topmost stackframe in user code
 	-r	displays location of topmost stackframe (including frames inside private runtime functions)
 	-g	displays location of go instruction that created the goroutine
+	-s	displays location of the start function
 	-t	displays stack trace of goroutine
 
 If no flag is specified the default is -u.

pkg/proc/variables.go

@@ -143,6 +143,7 @@ type G struct {
 	SP         uint64 // SP of goroutine when it was parked.
 	BP         uint64 // BP of goroutine when it was parked (go >= 1.7).
 	GoPC       uint64 // PC of 'go' statement that created this goroutine.
+	StartPC    uint64 // PC of the first function run on this goroutine.
 	WaitReason string // Reason for goroutine being parked.
 	Status     uint64
 	stkbarVar  *Variable // stkbar field of g struct
@@ -422,6 +423,7 @@ func (gvar *Variable) parseG() (*G, error) {
 	}
 	id, _ := constant.Int64Val(gvar.fieldVariable("goid").Value)
 	gopc, _ := constant.Int64Val(gvar.fieldVariable("gopc").Value)
+	startpc, _ := constant.Int64Val(gvar.fieldVariable("startpc").Value)
 	waitReason := ""
 	if wrvar := gvar.fieldVariable("waitreason"); wrvar.Value != nil {
 		switch wrvar.Kind {
@@ -451,6 +453,7 @@ func (gvar *Variable) parseG() (*G, error) {
 	g := &G{
 		ID:         int(id),
 		GoPC:       uint64(gopc),
+		StartPC:    uint64(startpc),
 		PC:         uint64(pc),
 		SP:         uint64(sp),
 		BP:         uint64(bp),
@@ -553,6 +556,12 @@ func (g *G) Go() Location {
 	return Location{PC: g.GoPC, File: f, Line: l, Fn: fn}
 }
 
+// StartLoc returns the starting location of the goroutine.
+func (g *G) StartLoc() Location {
+	f, l, fn := g.variable.bi.PCToLine(g.StartPC)
+	return Location{PC: g.StartPC, File: f, Line: l, Fn: fn}
+}
+
 // Returns the list of saved return addresses used by stack barriers
 func (g *G) stkbar() ([]savedLR, error) {
 	if g.stkbarVar == nil { // stack barriers were removed in Go 1.9

pkg/terminal/command.go

@@ -142,13 +142,14 @@ See also: "help on", "help cond" and "help clear"`},
 If called with the linespec argument it will delete all the breakpoints matching the linespec. If linespec is omitted all breakpoints are deleted.`},
 		{aliases: []string{"goroutines"}, cmdFn: goroutines, helpMsg: `List program goroutines.
 
-	goroutines [-u (default: user location)|-r (runtime location)|-g (go statement location) ] [ -t (stack trace)]
+	goroutines [-u (default: user location)|-r (runtime location)|-g (go statement location)|-s (start location)] [ -t (stack trace)]
 
 Print out info for every goroutine. The flag controls what information is shown along with each goroutine:
 
 	-u	displays location of topmost stackframe in user code
 	-r	displays location of topmost stackframe (including frames inside private runtime functions)
 	-g	displays location of go instruction that created the goroutine
+	-s	displays location of the start function
 	-t	displays stack trace of goroutine
 
 If no flag is specified the default is -u.`},
@@ -544,6 +545,8 @@ func goroutines(t *Term, ctx callContext, argstr string) error {
 				fgl = fglRuntimeCurrent
 			case "-g":
 				fgl = fglGo
+			case "-s":
+				fgl = fglStart
 			case "-t":
 				bPrintStack = true
 			case "":
@@ -706,6 +709,7 @@ const (
 	fglRuntimeCurrent = formatGoroutineLoc(iota)
 	fglUserCurrent
 	fglGo
+	fglStart
 )
 
 func formatLocation(loc api.Location) string {
@@ -732,6 +736,9 @@ func formatGoroutine(g *api.Goroutine, fgl formatGoroutineLoc) string {
 	case fglGo:
 		locname = "Go"
 		loc = g.GoStatementLoc
+	case fglStart:
+		locname = "Start"
+		loc = g.StartLoc
 	}
 	thread := ""
 	if g.ThreadID != 0 {
@@ -741,11 +748,12 @@ func formatGoroutine(g *api.Goroutine, fgl formatGoroutineLoc) string {
 }
 
 func writeGoroutineLong(w io.Writer, g *api.Goroutine, prefix string) {
-	fmt.Fprintf(w, "%sGoroutine %d:\n%s\tRuntime: %s\n%s\tUser: %s\n%s\tGo: %s\n",
+	fmt.Fprintf(w, "%sGoroutine %d:\n%s\tRuntime: %s\n%s\tUser: %s\n%s\tGo: %s\n%s\tStart: %s\n",
 		prefix, g.ID,
 		prefix, formatLocation(g.CurrentLoc),
 		prefix, formatLocation(g.UserCurrentLoc),
-		prefix, formatLocation(g.GoStatementLoc))
+		prefix, formatLocation(g.GoStatementLoc),
+		prefix, formatLocation(g.StartLoc))
 }
 
 func parseArgs(args string) ([]string, error) {

service/api/conversions.go

@@ -235,6 +235,7 @@ func ConvertGoroutine(g *proc.G) *Goroutine {
 		CurrentLoc:     ConvertLocation(g.CurrentLoc),
 		UserCurrentLoc: ConvertLocation(g.UserCurrent()),
 		GoStatementLoc: ConvertLocation(g.Go()),
+		StartLoc:       ConvertLocation(g.StartLoc()),
 		ThreadID:       tid,
 	}
 }

service/api/types.go

@@ -256,6 +256,8 @@ type Goroutine struct {
 	UserCurrentLoc Location `json:"userCurrentLoc"`
 	// Location of the go instruction that started this goroutine
 	GoStatementLoc Location `json:"goStatementLoc"`
+	// Location of the starting function
+	StartLoc Location `json:"startLoc"`
 	// ID of the associated thread for running goroutines
 	ThreadID int `json:"threadID"`
 }