8.5.4 Date Struction for building Control Flow Graphs
Basic blocks may be created and destroyed as the program is modified in the optimization process. Thus, space must be made available for growing collections of blocks. Storage reclamation is essential to handle optimization of large programs.
Since the structure of the flow graph varies with time, the data structure for blocks might keep pointers to lists of successors.
Since statements within the block change with time, it is reasonable to keep the intermediate representation as a linked list and reclaim storage of unused statements. Another possibility is to allocate dynamically on a heap and then garbage collect (see a data structures text if the terms heap and garbage collection are not familiar) when the heap runs out. See Module 12 for a discussion of garbage collection.