swift

9aff288b - Optimizer: re-implement the `pointer_to_address` SILCombine peephole optimizations in swift

Optimizer: re-implement the `pointer_to_address` SILCombine peephole optimizations in swift Which consists of * removing redundant `address_to_pointer`-`pointer_to_address` pairs * optimize `index_raw_pointer` of a manually computed stride to `index_addr` * remove or increase the alignment based on a "assumeAlignment" builtin This is a big code cleanup but also has some functional differences for the `address_to_pointer`-`pointer_to_address` pair removal: * It's not done if the resulting SIL would result in a (detectable) use-after-dealloc_stack memory lifetime failure. * It's not done if `copy_value`s must be inserted or borrow-scopes must be extended to comply with ownership rules (this was the task of the OwnershipRAUWHelper). Inserting copies is bad anyway. Extending borrow-scopes would only be required if the original lifetime of the pointer extends a borrow scope - which shouldn't happen in save code. Therefore this is a very rare case which is not worth handling.