Andrew Trick badc5658bb Fix SIL MemBehavior queries with access markers. ...

This is in prepration for other bug fixes.

Clarify the SIL utilities that return canonical address values for
formal access given the address used by some memory operation:

- stripAccessMarkers
- getAddressAccess
- getAccessedAddress

These are closely related to the code in MemAccessUtils.

Make sure passes use these utilities consistently so that
optimizations aren't defeated by normal variations in SIL patterns.

Create an isLetAddress() utility alongside these basic utilities to
make sure it is used consistently with the address corresponding to
formal access. When this query is used inconsistently, it defeats
optimization. It can also cause correctness bugs because some
optimizations assume that 'let' initialization is only performed on a
unique address value.

Functional changes to Memory Behavior:

- An instruction with side effects now conservatively still has side
  effects even when the queried value is a 'let'. Let values are
  certainly sensitive to side effects, such as the parent object being
  deallocated.

- Return the correct MemBehavior for begin/end_access markers.

2020-03-03 09:24:18 -08:00

13 KiB

Raw Blame History

View Raw