add assert to get_Block_MacroBlock()

[r15964]

diff --git a/ir/ir/irnode.c b/ir/ir/irnode.c
index 616211a..104c8d5 100644 (file)
--- a/ir/ir/irnode.c
+++ b/ir/ir/irnode.c
@@ -860,8 +860,13 @@ void set_Block_extbb(ir_node *block, ir_extblk *extblk) {
 
 /* returns the macro block header of a block. */
 ir_node *get_Block_MacroBlock(const ir_node *block) {
+       ir_node *mbh;
        assert(is_Block(block));
-       return get_irn_n(block, -1);
+       mbh = get_irn_n(block, -1);
+       /* once macro block header is respected by all optimizations,
+          this assert can be removed */
+       assert(mbh != NULL);
+       return mbh;
 }
 
 /* returns the graph of a Block. */