[MVT][SVE] Scalable vector MVTs (1/3)

This patch adds a few helper functions to obtain new vector
value types based on existing ones without needing to care
about whether they are scalable or not.

I've confined their use to a few common locations right now,
and targets that don't have scalable vectors should never
need to care about these.

Patch by Graham Hunter.

Differential Revision: https://reviews.llvm.org/D32017

llvm-svn: 300838

2 files changed, 9 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 78fddb5ce8f..1a7d7b7af5f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -1293,12 +1293,9 @@ void DAGTypeLegalizer::SplitVecRes_ExtendOp(SDNode *N, SDValue &Lo,
   if ((NumElements & 1) == 0 &&
       SrcVT.getSizeInBits() * 2 < DestVT.getSizeInBits()) {
     LLVMContext &Ctx = *DAG.getContext();
-    EVT NewSrcVT = EVT::getVectorVT(
-        Ctx, EVT::getIntegerVT(
-                 Ctx, SrcVT.getScalarSizeInBits() * 2),
-        NumElements);
-    EVT SplitSrcVT =
-        EVT::getVectorVT(Ctx, SrcVT.getVectorElementType(), NumElements / 2);
+    EVT NewSrcVT = SrcVT.widenIntegerVectorElementType(Ctx);
+    EVT SplitSrcVT = SrcVT.getHalfNumVectorElementsVT(Ctx);
+
     EVT SplitLoVT, SplitHiVT;
     std::tie(SplitLoVT, SplitHiVT) = DAG.GetSplitDestVTs(NewSrcVT);
     if (TLI.isTypeLegal(SrcVT) && !TLI.isTypeLegal(SplitSrcVT) &&
@@ -3012,8 +3009,8 @@ SDValue DAGTypeLegalizer::WidenVSELECTAndMask(SDNode *N) {
   // Don't touch if this will be scalarized.
   EVT FinalVT = VSelVT;
   while (getTypeAction(FinalVT) == TargetLowering::TypeSplitVector)
-    FinalVT = EVT::getVectorVT(Ctx, FinalVT.getVectorElementType(),
-                               FinalVT.getVectorNumElements() / 2);
+    FinalVT = FinalVT.getHalfNumVectorElementsVT(Ctx);
+
   if (FinalVT.getVectorNumElements() == 1)
     return SDValue();
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 459d22d1e5c..a098a69143e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -7573,14 +7573,11 @@ unsigned SelectionDAG::InferPtrAlignment(SDValue Ptr) const {
 std::pair<EVT, EVT> SelectionDAG::GetSplitDestVTs(const EVT &VT) const {
   // Currently all types are split in half.
   EVT LoVT, HiVT;
-  if (!VT.isVector()) {
+  if (!VT.isVector())
     LoVT = HiVT = TLI->getTypeToTransformTo(*getContext(), VT);
-  } else {
-    unsigned NumElements = VT.getVectorNumElements();
-    assert(!(NumElements & 1) && "Splitting vector, but not in half!");
-    LoVT = HiVT = EVT::getVectorVT(*getContext(), VT.getVectorElementType(),
-                                   NumElements/2);
-  }
+  else
+    LoVT = HiVT = VT.getHalfNumVectorElementsVT(*getContext());
+
   return std::make_pair(LoVT, HiVT);
 }