parser+codegen: Add support for 'return' statement

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

core/codegen.c

@@ -25,6 +25,48 @@ resolve_func(struct rifle_state *state, struct ast_node *root)
     return mu_gen_label(state, symbol->name, symbol->pub);
 }
 
+static int
+resolve_return(struct rifle_state *state, struct ast_node *root)
+{
+    struct symbol *func_sym;
+    struct ast_node *rhs;
+    data_type_t type;
+
+    if (state == NULL || root == NULL) {
+        return -1;
+    }
+
+    if ((func_sym = state->cur_func) == NULL) {
+        return -1;
+    }
+
+    if (root->type != AST_RETURN) {
+        return -1;
+    }
+
+    if ((rhs = root->right) == NULL) {
+        trace_error(state, "internal: return has no rhs\n");
+        return -1;
+    }
+
+    type = data_raw_type(&func_sym->dtype) ;
+    switch (rhs->type) {
+    case AST_NUMBER:
+        mu_gen_retimm(
+            state,
+            rhs->v,
+            type_to_msize(type)
+        );
+
+        break;
+    default:
+        trace_error(state, "internal: bad ast node in return\n");
+        return -1;
+    }
+
+    return 0;
+}
+
 int
 cg_resolve_node(struct rifle_state *state, struct ast_node *root)
 {
@@ -38,6 +80,12 @@ cg_resolve_node(struct rifle_state *state, struct ast_node *root)
             return -1;
         }
 
+        break;
+    case AST_RETURN:
+        if (resolve_return(state, root) < 0) {
+            return -1;
+        }
+
         break;
     default:
         trace_error(state, "unknown ast node %d\n", root->type);