backend: Add interface to generate ret instruction

Signed-off-by: Ian Moffett <ian@mirocom.org>

backend/x86_64.c

@@ -25,3 +25,17 @@ mu_gen_label(struct rifle_state *state, const char *name, bool global)
     return 0;
 }
 
+int
+mu_gen_ret(struct rifle_state *state)
+{
+    if (state == NULL) {
+        return -1;
+    }
+
+    fprintf(
+        state->out_fp,
+        INST("ret")
+    );
+
+    return 0;
+}

inc/rifle/mu.h

@@ -6,6 +6,9 @@
 #include <stdbool.h>
 #include "rifle/state.h"
 
+#define INST(inst) \
+    "    " inst "\n"
+
 /*
  * Generate a named label
  *
@@ -17,4 +20,13 @@
  */
 int mu_gen_label(struct rifle_state *state, const char *name, bool global);
 
+/*
+ * Generate a return instruction
+ *
+ * @state: Compiler state
+ *
+ * Returns zero on success
+ */
+int mu_gen_ret(struct rifle_state *state);
+
 #endif  /* !RIFLE_MU_H */