swift234

SILCombine: Add another index_raw_pointer -> index_addr peephole

This time involving builtin array operations.

Take something like this:
   %stride = Builtin.strideof(T) * %distance
   %ptr' = index_raw_pointer %ptr, %stride
     = builtin "takeArrayFrontToBack"<Int>(%metatype, %ptr', ...

And convert it to this:
   %addr = pointer_to_address %ptr, $T
   %result = index_addr %addr, %distance
   %ptr' = address_to_pointer result : $RawPointer
     = builtin "takeArrayFrontToBack"<Int>(%metatype, %ptr', ...

rdar://19608094

Swift SVN r24772