cmd/internal/gc, cmd/internal/ld: add memprofilerate flag

Also call runtime.GC before exit to ensure
that the profiler picks up all allocations.

Fixes #10537.

Change-Id: Ibfbfc88652ac0ce30a6d1ae392f919df6c1e8126
Reviewed-on: https://go-review.googlesource.com/9261Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/internal/gc/lex.go

@@ -233,6 +233,7 @@ func Main() {
 	}
 	obj.Flagstr("cpuprofile", "file: write cpu profile to file", &cpuprofile)
 	obj.Flagstr("memprofile", "file: write memory profile to file", &memprofile)
+	obj.Flagint64("memprofilerate", "set runtime.MemProfileRate", &memprofilerate)
 	obj.Flagparse(usage)
 
 	if flag_dynlink {

src/cmd/internal/gc/util.go

@@ -3,6 +3,7 @@ package gc
 import (
 	"cmd/internal/obj"
 	"os"
+	"runtime"
 	"runtime/pprof"
 	"strconv"
 	"strings"
@@ -42,14 +43,6 @@ func plan9quote(s string) string {
 	return s
 }
 
-// simulation of int(*s++) in C
-func intstarstringplusplus(s string) (int, string) {
-	if s == "" {
-		return 0, ""
-	}
-	return int(s[0]), s[1:]
-}
-
 // strings.Compare, introduced in Go 1.5.
 func stringsCompare(a, b string) int {
 	if a == b {
@@ -76,8 +69,11 @@ func Exit(code int) {
 	os.Exit(code)
 }
 
-var cpuprofile string
-var memprofile string
+var (
+	cpuprofile     string
+	memprofile     string
+	memprofilerate int64
+)
 
 func startProfile() {
 	if cpuprofile != "" {
@@ -91,11 +87,15 @@ func startProfile() {
 		AtExit(pprof.StopCPUProfile)
 	}
 	if memprofile != "" {
+		if memprofilerate != 0 {
+			runtime.MemProfileRate = int(memprofilerate)
+		}
 		f, err := os.Create(memprofile)
 		if err != nil {
 			Fatal("%v", err)
 		}
 		AtExit(func() {
+			runtime.GC() // profile all outstanding allocations
 			if err := pprof.WriteHeapProfile(f); err != nil {
 				Fatal("%v", err)
 			}

src/cmd/internal/ld/pobj.go

@@ -140,6 +140,7 @@ func Ldmain() {
 	}
 	obj.Flagstr("cpuprofile", "file: write cpu profile to file", &cpuprofile)
 	obj.Flagstr("memprofile", "file: write memory profile to file", &memprofile)
+	obj.Flagint64("memprofilerate", "set runtime.MemProfileRate", &memprofilerate)
 	obj.Flagparse(usage)
 	startProfile()
 	Ctxt.Bso = &Bso

src/cmd/internal/ld/util.go

@@ -11,6 +11,7 @@ import (
 	"io"
 	"log"
 	"os"
+	"runtime"
 	"runtime/pprof"
 	"strings"
 	"time"
@@ -300,8 +301,11 @@ func Exit(code int) {
 	os.Exit(code)
 }
 
-var cpuprofile string
-var memprofile string
+var (
+	cpuprofile     string
+	memprofile     string
+	memprofilerate int64
+)
 
 func startProfile() {
 	if cpuprofile != "" {
@@ -315,11 +319,15 @@ func startProfile() {
 		AtExit(pprof.StopCPUProfile)
 	}
 	if memprofile != "" {
+		if memprofilerate != 0 {
+			runtime.MemProfileRate = int(memprofilerate)
+		}
 		f, err := os.Create(memprofile)
 		if err != nil {
 			log.Fatalf("%v", err)
 		}
 		AtExit(func() {
+			runtime.GC() // profile all outstanding allocations
 			if err := pprof.WriteHeapProfile(f); err != nil {
 				log.Fatalf("%v", err)
 			}