Executes pre before visiting the predecessor of a node, post after.
irg_walk uses the visited flag in irg and the nodes to determine visited
nodes. It executes inc_irg_visited(current_ir_graph) to generate a new
- flag.
+ flag. It marks the node as visited before executing pre.
The void* env can be used to pass status information between the
pre and post functions. */
void irg_walk(ir_node *node,