pprof: make it work on windows again

- pprof is a perl script, so go command should invoke
  perl instead of trying to run pprof directly;
- pprof should use "go tool nm" unconditionally on windows,
  no one else can extract symbols from Go program;
- pprof should use "go tool nm" instead of "6nm".

Fixes issue 3879.

R=golang-dev, r
CC=golang-dev
http://codereview.appspot.com/6445082

1 files changed, 11 insertions, 1 deletions

diff --git a/src/cmd/go/tool.go b/src/cmd/go/tool.go
index cb463a2e7..01e8ff6bb 100644
--- a/src/cmd/go/tool.go
+++ b/src/cmd/go/tool.go
@@ -47,7 +47,7 @@ const toolWindowsExtension = ".exe"
 
 func tool(name string) string {
 	p := filepath.Join(toolDir, name)
-	if toolIsWindows {
+	if toolIsWindows && name != "pprof" {
 		p += toolWindowsExtension
 	}
 	return p
@@ -76,6 +76,16 @@ func runTool(cmd *Command, args []string) {
 		setExitStatus(3)
 		return
 	}
+	if toolIsWindows && toolName == "pprof" {
+		args = append([]string{"perl", toolPath}, args[1:]...)
+		var err error
+		toolPath, err = exec.LookPath("perl")
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "go tool: perl not found\n")
+			setExitStatus(3)
+			return
+		}
+	}
 
 	if toolN {
 		fmt.Printf("%s %s\n", toolPath, strings.Join(args[1:], " "))