Ideas for AST-level optimizations

[iamdefinitelyahuman]

This is a list of ideas for optimizations that could be implemented via AST modification. Some of these ideas are probably bad. This is a living list, in no way finalized, and will likely change in the future.

• in __init__, remove any assignments of self.var = [zero value]
• when a storage variable is referenced more than once without being written to, create a memory variable
• remove memory variables that are initialized but never used
• for an if statement where both the if and else blocks end in a return, move the else block logic into the body of the parent block (note: potential scoping concerns)
• convert > 0 to != 0 for unsigned integer comparisons
• if a memory variable is initialized and only referenced once, replace the reference with the right-hand side of the initialization
• if the final node in a function body is a for loop, and the function returns None, replace any return statements inside the function with break
• if constant folding results in if True: or if False: remove the block or the else block (consider scoping here)
• within the context of a for loop, if there are multiple lookups of some_long_array[i] without any assignments, copy the value to a new memory value to save on lookups