ARM cost model: Address computation in vector mem ops not free

Adds a function to target transform info to query for the cost of address
computation. The cost model analysis pass now also queries this interface.
The code in LoopVectorize adds the cost of address computation as part of the
memory instruction cost calculation. Only there, we know whether the instruction
will be scalarized or not.
Increase the penality for inserting in to D registers on swift. This becomes
necessary because we now always assume that address computation has a cost and
three is a closer value to the architecture.

radar://13097204

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174713 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/TargetTransformInfo.h

@@ -314,6 +314,12 @@ public:
   /// split during legalization. Zero is returned when the answer is unknown.
   virtual unsigned getNumberOfParts(Type *Tp) const;
 
+  /// \returns The cost of the address computation. For most targets this can be
+  /// merged into the instruction indexing mode. Some targets might want to
+  /// distinguish between address computation for memory operations on vector
+  /// types and scalar types. Such targets should override this function.
+  virtual unsigned getAddressComputationCost(Type *Ty) const;
+
   /// @}
 
   /// Analysis group identification.