Only allocate space for variables that are actually used

2 files changed, 26 insertions, 1 deletions

diff --git a/ast.h b/ast.h
index 7c6c4b9..d8e8a97 100644
--- a/ast.h
+++ b/ast.h
@@ -935,6 +935,7 @@ struct ast_variable_definition_t
     int					level;
 
     gboolean				field;
+    gboolean				used;
 };
 
 struct ast_label_definition_t
diff --git a/offsets.c b/offsets.c
index 93ead6f..32f3614 100644
--- a/offsets.c
+++ b/offsets.c
@@ -19,6 +19,27 @@
 #include "ast.h"
 
 static void
+mark_used (node_t *node, gpointer data)
+{
+    if (node->common.type == NODE_LOAD)
+    {
+	node->load.definition->used = TRUE;
+    }
+    else if (node->common.type == NODE_STORE)
+    {
+	node->store.definition->used = TRUE;
+    }
+    else if (node->common.type == NODE_LOAD_IND)
+    {
+	node->load_ind.definition->used = TRUE;
+    }
+    else if (node->common.type == NODE_STORE_IND)
+    {
+	node->store_ind.definition->used = TRUE;
+    }
+}
+    
+static void
 list_def (gpointer key, gpointer value, gpointer data)
 {
     GPtrArray *array = data;
@@ -38,7 +59,8 @@ assign_offsets (symbol_table_t *symbols, int offset, int *max)
     {
 	ast_definition_t *definition = definitions->pdata[i];
 
-	if (definition->common.type == AST_VARIABLE_DEFINITION)
+	if (definition->common.type == AST_VARIABLE_DEFINITION	&&
+	    definition->variable.used)
 	{
 	    int size = ast_type_spec_get_size (definition->variable.type_spec);
 
@@ -123,6 +145,8 @@ do_offsets (ast_t *ast, int offset, int *max)
 gboolean
 offsets (ast_t *ast)
 {
+    node_breadth_first (ast->program.enter, mark_used, NULL);
+
     do_offsets (ast, 0, NULL);
 
     /* The offsets pass can never fail */