+ allocate_extblk(block, env);
+ extbb = get_Block_extbb(block);
+ set_Block_extbb(block, sentinel);
+ }
+
+ /* replace all sentinels by the extbb info */
+ prev = block;
+ while (1) {
+ if (get_Block_extbb(prev) != sentinel)
+ break;
+ set_Block_extbb(prev, extbb);
+ prev = get_Block_cfgpred_block(prev, 0);
+ }