swift234

[sil-aa] Convert AliasAnalysis::alias(SILInstruction *, SILValue) -> AliasAnalysis::getMemoryBehavior(SILInstruction *, SILValue).

AliasAnalysis::getMemoryBehavior() returns a SILInstruction::MemoryBehavior
object that specifies the memory behavior of the SILInstruction with respect to
the SILValue. This name fits better the intention behind the aforementioned
poorly named alias instruction.

This is analogous to memdep in LLVM, except using the enum values from
SILInstruction::MemoryBehavior since we already have them.

Currently it always returns the most conservative answer, MayHaveSideEffects for
everything.

The patch also updates SILCodeMotion in light of these changes.

Swift SVN r13457