1 files changed, 34 insertions, 5 deletions

diff --git a/src/cmd/go/run.go b/src/cmd/go/run.go
index e6dadd229..ef8aa95a3 100644
--- a/src/cmd/go/run.go
+++ b/src/cmd/go/run.go
@@ -8,16 +8,43 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"runtime"
 	"strings"
 )
 
+var execCmd []string // -exec flag, for run and test
+
+func findExecCmd() []string {
+	if execCmd != nil {
+		return execCmd
+	}
+	execCmd = []string{} // avoid work the second time
+	if goos == runtime.GOOS && goarch == runtime.GOARCH {
+		return execCmd
+	}
+	path, err := exec.LookPath(fmt.Sprintf("go_%s_%s_exec", goos, goarch))
+	if err == nil {
+		execCmd = []string{path}
+	}
+	return execCmd
+}
+
 var cmdRun = &Command{
-	UsageLine: "run [build flags] gofiles... [arguments...]",
+	UsageLine: "run [build flags] [-exec xprog] gofiles... [arguments...]",
 	Short:     "compile and run Go program",
 	Long: `
 Run compiles and runs the main package comprising the named Go source files.
 A Go source file is defined to be a file ending in a literal ".go" suffix.
 
+By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
+If the -exec flag is given, 'go run' invokes the binary using xprog: 'xprog a.out arguments...'.
+If the -exec flag is not given, GOOS or GOARCH is different from the system
+default, and a program named go_$GOOS_$GOARCH_exec can be found
+on the current search path, 'go run' invokes the binary using that program,
+for example 'go_nacl_386_exec a.out arguments...'. This allows execution of
+cross-compiled programs when a simulator or other execution method is
+available.
+
 For more about build flags, see 'go help build'.
 
 See also: go build.
@@ -28,6 +55,7 @@ func init() {
 	cmdRun.Run = runRun // break init loop
 
 	addBuildFlags(cmdRun)
+	cmdRun.Flag.Var((*stringsFlag)(&execCmd), "exec", "")
 }
 
 func printStderr(args ...interface{}) (int, error) {
@@ -58,6 +86,7 @@ func runRun(cmd *Command, args []string) {
 	if p.Error != nil {
 		fatalf("%s", p.Error)
 	}
+	p.omitDWARF = true
 	for _, err := range p.DepsErrors {
 		errorf("%s", err)
 	}
@@ -89,20 +118,20 @@ func runRun(cmd *Command, args []string) {
 // runProgram is the action for running a binary that has already
 // been compiled.  We ignore exit status.
 func (b *builder) runProgram(a *action) error {
+	cmdline := stringList(findExecCmd(), a.deps[0].target, a.args)
 	if buildN || buildX {
-		b.showcmd("", "%s %s", a.deps[0].target, strings.Join(a.args, " "))
+		b.showcmd("", "%s", strings.Join(cmdline, " "))
 		if buildN {
 			return nil
 		}
 	}
 
-	runStdin(a.deps[0].target, a.args)
+	runStdin(cmdline)
 	return nil
 }
 
 // runStdin is like run, but connects Stdin.
-func runStdin(cmdargs ...interface{}) {
-	cmdline := stringList(cmdargs...)
+func runStdin(cmdline []string) {
 	cmd := exec.Command(cmdline[0], cmdline[1:]...)
 	cmd.Stdin = os.Stdin
 	cmd.Stdout = os.Stdout