go/ssa/interp: fix fallout from recent runtime refactoring.

(It's not clear at what point a more robust solution would be worthwhile.)

LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/142700043

go/ssa/interp/external.go

@@ -78,6 +78,7 @@ func init() {
 		"math.Ldexp":                       ext۰math۰Ldexp,
 		"math.Log":                         ext۰math۰Log,
 		"math.Min":                         ext۰math۰Min,
+		"os.runtime_args":                  ext۰os۰runtime_args,
 		"reflect.New":                      ext۰reflect۰New,
 		"reflect.TypeOf":                   ext۰reflect۰TypeOf,
 		"reflect.ValueOf":                  ext۰reflect۰ValueOf,
@@ -127,6 +128,7 @@ func init() {
 		"syscall.ReadDirent":               ext۰syscall۰ReadDirent,
 		"syscall.Stat":                     ext۰syscall۰Stat,
 		"syscall.Write":                    ext۰syscall۰Write,
+		"syscall.runtime_envs":             ext۰runtime۰environ,
 		"time.Sleep":                       ext۰time۰Sleep,
 		"time.now":                         ext۰time۰now,
 	}
@@ -221,6 +223,10 @@ func ext۰math۰Log(fr *frame, args []value) value {
 	return math.Log(args[0].(float64))
 }
 
+func ext۰os۰runtime_args(fr *frame, args []value) value {
+	return fr.i.osArgs
+}
+
 func ext۰runtime۰Breakpoint(fr *frame, args []value) value {
 	runtime.Breakpoint()
 	return nil
@@ -281,13 +287,8 @@ func ext۰runtime۰FuncForPC(fr *frame, args []value) value {
 }
 
 func ext۰runtime۰environ(fr *frame, args []value) value {
-	// We don't return syscall.envs (see Interpret()) because it's
+	// This function also implements syscall.runtime_envs.
-	// not a dependency of runtime so the package might not exist.
+	return environ
-	var env []value
-	for _, s := range os.Environ() {
-		env = append(env, s)
-	}
-	return env
 }
 
 func ext۰runtime۰getgoroot(fr *frame, args []value) value {

go/ssa/interp/interp.go

@@ -75,6 +75,7 @@ type methodSet map[string]*ssa.Function
 
 // State shared between all interpreted goroutines.
 type interpreter struct {
+	osArgs             []value              // the value of os.Args
 	prog               *ssa.Program         // the SSA program
 	globals            map[ssa.Value]*value // addresses of global variables (immutable)
 	mode               Mode                 // interpreter options
@@ -620,6 +621,16 @@ func setGlobal(i *interpreter, pkg *ssa.Package, name string, v value) {
 	panic("no global variable: " + pkg.Object.Path() + "." + name)
 }
 
+var environ []value
+
+func init() {
+	for _, s := range os.Environ() {
+		environ = append(environ, s)
+	}
+	environ = append(environ, "GOSSAINTERP=1")
+	environ = append(environ, "GOARCH="+runtime.GOARCH)
+}
+
 // Interpret interprets the Go program whose main package is mainpkg.
 // mode specifies various interpreter options.  filename and args are
 // the initial values of os.Args for the target program.  sizes is the
@@ -645,6 +656,11 @@ func Interpret(mainpkg *ssa.Package, mode Mode, sizes types.Sizes, filename stri
 
 	initReflect(i)
 
+	i.osArgs = append(i.osArgs, filename)
+	for _, arg := range args {
+		i.osArgs = append(i.osArgs, arg)
+	}
+
 	for _, pkg := range i.prog.AllPackages() {
 		// Initialize global storage.
 		for _, m := range pkg.Members {
@@ -658,13 +674,7 @@ func Interpret(mainpkg *ssa.Package, mode Mode, sizes types.Sizes, filename stri
 		// Ad-hoc initialization for magic system variables.
 		switch pkg.Object.Path() {
 		case "syscall":
-			var envs []value
+			setGlobal(i, pkg, "envs", environ)
-			for _, s := range os.Environ() {
-				envs = append(envs, s)
-			}
-			envs = append(envs, "GOSSAINTERP=1")
-			envs = append(envs, "GOARCH="+runtime.GOARCH)
-			setGlobal(i, pkg, "envs", envs)
 
 		case "runtime":
 			sz := sizes.Sizeof(pkg.Object.Scope().Lookup("MemStats").Type())
@@ -682,13 +692,6 @@ func Interpret(mainpkg *ssa.Package, mode Mode, sizes types.Sizes, filename stri
 					}
 				}
 			}
-
-		case "os":
-			Args := []value{filename}
-			for _, s := range args {
-				Args = append(Args, s)
-			}
-			setGlobal(i, pkg, "Args", Args)
 		}
 	}