Lecture 178 - Generating unions

codegen.c

@@ -565,6 +565,19 @@ void codegen_generate_global_variable_for_struct(struct node* node)
     char tmp_buf[256];
     asm_push("%s: %s 0", node->var.name, asm_keyword_for_size(variable_size(node), tmp_buf));
 }
+
+void codegen_generate_global_variable_for_union(struct node* node)
+{
+    if (node->var.val != NULL)
+    {
+        compiler_error(current_process, "We dont yet support values for unions");
+        return;
+    }
+
+    char tmp_buf[256];
+    asm_push("%s: %s 0", node->var.name, asm_keyword_for_size(variable_size(node), tmp_buf));
+}
+
 void codegen_generate_global_variable(struct node *node)
 {
     asm_push("; %s %s", node->var.type.type_str, node->var.name);
@@ -581,6 +594,10 @@ void codegen_generate_global_variable(struct node *node)
     case DATA_TYPE_STRUCT:
         codegen_generate_global_variable_for_struct(node);
         break;
+
+    case DATA_TYPE_UNION:
+        codegen_generate_global_variable_for_union(node);
+        break;
     case DATA_TYPE_DOUBLE:
     case DATA_TYPE_FLOAT:
         compiler_error(current_process, "Doubles and floats are not supported in our subset of C\n");
@@ -596,6 +613,14 @@ void codegen_generate_struct(struct node* node)
     }
 
 }
+
+void codegen_generate_union(struct node* node)
+{
+    if (node->flags & NODE_FLAG_HAS_VARIABLE_COMBINED)
+    {
+        codegen_generate_global_variable(node->_union.var);
+    }
+}
 void codegen_generate_data_section_part(struct node *node)
 {
     switch (node->type)
@@ -608,6 +633,10 @@ void codegen_generate_data_section_part(struct node *node)
         codegen_generate_struct(node);
         break;
 
+    case NODE_TYPE_UNION:
+        codegen_generate_union(node);
+        break;
+
     default:
         break;
     }

test.c

@@ -1,6 +1,13 @@
 
+union abc
+{
+    int x;
+    int y;
+};
+
+union abc a;
 int main()
 {
-    int* x;
-    *x = 50;
+    a.x = 50;
+    return a.y;
 }