add openssl sha1,sha256,sha512

ssa/expr.go

@@ -1022,6 +1022,10 @@ func (b Builder) Do(da DoAction, fn Expr, args ...Expr) (ret Expr) {
 // Go spec (excluding "make" and "new").
 func (b Builder) BuiltinCall(fn string, args ...Expr) (ret Expr) {
 	switch fn {
+	case "max":
+		fallthrough
+	case "min":
+		return b.max(args...)
 	case "len":
 		if len(args) == 1 {
 			arg := args[0]
@@ -1128,6 +1132,12 @@ func (b Builder) BuiltinCall(fn string, args ...Expr) (ret Expr) {
 	panic("todo: " + fn)
 }
 
+// max return the max value for the args
+func (b Builder) max(args ...Expr) (ret Expr) {
+	//todo
+	return args[len(args)-1]
+}
+
 // Println prints the arguments to stderr, followed by a newline.
 func (b Builder) Println(args ...Expr) (ret Expr) {
 	return b.PrintEx(true, args...)