[InterleavedAccess] Add a pass InterleavedAccess to identify interleaved memory accesses and transform into target specific intrinsics.

E.g. An interleaved load (Factor = 2):
        %wide.vec = load <8 x i32>, <8 x i32>* %ptr
        %v0 = shuffle <8 x i32> %wide.vec, <8 x i32> undef, <0, 2, 4, 6>
        %v1 = shuffle <8 x i32> %wide.vec, <8 x i32> undef, <1, 3, 5, 7>
It can be transformed into a ld2 intrinsic in AArch64 backend or a vld2 intrinsic in ARM backend.

E.g. An interleaved store (Factor = 3):
        %i.vec = shuffle <8 x i32> %v0, <8 x i32> %v1, <0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11>
        store <12 x i32> %i.vec, <12 x i32>* %ptr
It can be transformed into a st3 intrinsic in AArch64 backend or a vst3 intrinsic in ARM backend.

Differential Revision: http://reviews.llvm.org/D10533


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240751 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetLowering.h

@@ -1597,6 +1597,35 @@ public:
     return false;
   }
 
+  /// \brief Get the maximum supported factor for interleaved memory accesses.
+  /// Default to be the minimum interleave factor: 2.
+  virtual unsigned getMaxSupportedInterleaveFactor() const { return 2; }
+
+  /// \brief Lower an interleaved load to target specific intrinsics. Return
+  /// true on success.
+  ///
+  /// \p LI is the vector load instruction.
+  /// \p Shuffles is the shufflevector list to DE-interleave the loaded vector.
+  /// \p Indices is the corresponding indices for each shufflevector.
+  /// \p Factor is the interleave factor.
+  virtual bool lowerInterleavedLoad(LoadInst *LI,
+                                    ArrayRef<ShuffleVectorInst *> Shuffles,
+                                    ArrayRef<unsigned> Indices,
+                                    unsigned Factor) const {
+    return false;
+  }
+
+  /// \brief Lower an interleaved store to target specific intrinsics. Return
+  /// true on success.
+  ///
+  /// \p SI is the vector store instruction.
+  /// \p SVI is the shufflevector to RE-interleave the stored vector.
+  /// \p Factor is the interleave factor.
+  virtual bool lowerInterleavedStore(StoreInst *SI, ShuffleVectorInst *SVI,
+                                     unsigned Factor) const {
+    return false;
+  }
+
   /// Return true if zero-extending the specific node Val to type VT2 is free
   /// (either because it's implicitly zero-extended such as ARM ldrb / ldrh or
   /// because it's folded such as X86 zero-extending loads).