[LV] Move interleaved access helper functions to VectorUtils (NFC)

This patch moves some helper functions related to interleaved access
vectorization out of LoopVectorize.cpp and into VectorUtils.cpp. We would like
to use these functions in a follow-on patch that improves interleaved load and
store lowering in (ARM/AArch64)ISelLowering.cpp. One of the functions was
already duplicated there and has been removed.

Differential Revision: https://reviews.llvm.org/D29398

llvm-svn: 293788

1 files changed, 85 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index 7e598f4..722f17a 100644
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -488,3 +488,88 @@ Instruction *llvm::propagateMetadata(Instruction *Inst, ArrayRef<Value *> VL) {
 
   return Inst;
 }
+
+Constant *llvm::createInterleaveMask(IRBuilder<> &Builder, unsigned VF,
+                                     unsigned NumVecs) {
+  SmallVector<Constant *, 16> Mask;
+  for (unsigned i = 0; i < VF; i++)
+    for (unsigned j = 0; j < NumVecs; j++)
+      Mask.push_back(Builder.getInt32(j * VF + i));
+
+  return ConstantVector::get(Mask);
+}
+
+Constant *llvm::createStrideMask(IRBuilder<> &Builder, unsigned Start,
+                                 unsigned Stride, unsigned VF) {
+  SmallVector<Constant *, 16> Mask;
+  for (unsigned i = 0; i < VF; i++)
+    Mask.push_back(Builder.getInt32(Start + i * Stride));
+
+  return ConstantVector::get(Mask);
+}
+
+Constant *llvm::createSequentialMask(IRBuilder<> &Builder, unsigned Start,
+                                     unsigned NumInts, unsigned NumUndefs) {
+  SmallVector<Constant *, 16> Mask;
+  for (unsigned i = 0; i < NumInts; i++)
+    Mask.push_back(Builder.getInt32(Start + i));
+
+  Constant *Undef = UndefValue::get(Builder.getInt32Ty());
+  for (unsigned i = 0; i < NumUndefs; i++)
+    Mask.push_back(Undef);
+
+  return ConstantVector::get(Mask);
+}
+
+/// A helper function for concatenating vectors. This function concatenates two
+/// vectors having the same element type. If the second vector has fewer
+/// elements than the first, it is padded with undefs.
+static Value *concatenateTwoVectors(IRBuilder<> &Builder, Value *V1,
+                                    Value *V2) {
+  VectorType *VecTy1 = dyn_cast<VectorType>(V1->getType());
+  VectorType *VecTy2 = dyn_cast<VectorType>(V2->getType());
+  assert(VecTy1 && VecTy2 &&
+         VecTy1->getScalarType() == VecTy2->getScalarType() &&
+         "Expect two vectors with the same element type");
+
+  unsigned NumElts1 = VecTy1->getNumElements();
+  unsigned NumElts2 = VecTy2->getNumElements();
+  assert(NumElts1 >= NumElts2 && "Unexpect the first vector has less elements");
+
+  if (NumElts1 > NumElts2) {
+    // Extend with UNDEFs.
+    Constant *ExtMask =
+        createSequentialMask(Builder, 0, NumElts2, NumElts1 - NumElts2);
+    V2 = Builder.CreateShuffleVector(V2, UndefValue::get(VecTy2), ExtMask);
+  }
+
+  Constant *Mask = createSequentialMask(Builder, 0, NumElts1 + NumElts2, 0);
+  return Builder.CreateShuffleVector(V1, V2, Mask);
+}
+
+Value *llvm::concatenateVectors(IRBuilder<> &Builder, ArrayRef<Value *> Vecs) {
+  unsigned NumVecs = Vecs.size();
+  assert(NumVecs > 1 && "Should be at least two vectors");
+
+  SmallVector<Value *, 8> ResList;
+  ResList.append(Vecs.begin(), Vecs.end());
+  do {
+    SmallVector<Value *, 8> TmpList;
+    for (unsigned i = 0; i < NumVecs - 1; i += 2) {
+      Value *V0 = ResList[i], *V1 = ResList[i + 1];
+      assert((V0->getType() == V1->getType() || i == NumVecs - 2) &&
+             "Only the last vector may have a different type");
+
+      TmpList.push_back(concatenateTwoVectors(Builder, V0, V1));
+    }
+
+    // Push the last vector if the total number of vectors is odd.
+    if (NumVecs % 2 != 0)
+      TmpList.push_back(ResList[NumVecs - 1]);
+
+    ResList = TmpList;
+    NumVecs = ResList.size();
+  } while (NumVecs > 1);
+
+  return ResList[0];
+}