[LegalizeVectorTypes] Allow single loads and stores for more short vectors

When lowering a load or store for TypeWidenVector, the type legalizer
would use a single load or store if the associated integer type was legal
or promoted. E.g. it loads a v4i8 as an i32 if i32 is legal/promotable.
(See https://reviews.llvm.org/rL236528 for reference.)

This applies that behaviour to vector types. If the vector type is
TypePromoteInteger, the element type is going to be TypePromoteInteger
as well, which will lead to have a single promoting load rather than N
individual promoting loads. For instance, if we have a v3i1, we would
now have a load of v4i1 instead of 3 loads of i1.

Patch by Guillaume Marques. Thanks!

Differential Revision: https://reviews.llvm.org/D56201

llvm-svn: 357120

1 files changed, 6 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index ab1b1c5e936..5ecfad7c7f1 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -4380,6 +4380,8 @@ static EVT FindMemType(SelectionDAG& DAG, const TargetLowering &TLI,
         isPowerOf2_32(WidenWidth / MemVTWidth) &&
         (MemVTWidth <= Width ||
          (Align!=0 && MemVTWidth<=AlignInBits && MemVTWidth<=Width+WidenEx))) {
+      if (MemVTWidth == WidenWidth)
+        return MemVT;
       RetVT = MemVT;
       break;
     }
@@ -4391,7 +4393,10 @@ static EVT FindMemType(SelectionDAG& DAG, const TargetLowering &TLI,
        VT >= (unsigned)MVT::FIRST_VECTOR_VALUETYPE; --VT) {
     EVT MemVT = (MVT::SimpleValueType) VT;
     unsigned MemVTWidth = MemVT.getSizeInBits();
-    if (TLI.isTypeLegal(MemVT) && WidenEltVT == MemVT.getVectorElementType() &&
+    auto Action = TLI.getTypeAction(*DAG.getContext(), MemVT);
+    if ((Action == TargetLowering::TypeLegal ||
+         Action == TargetLowering::TypePromoteInteger) &&
+        WidenEltVT == MemVT.getVectorElementType() &&
         (WidenWidth % MemVTWidth) == 0 &&
         isPowerOf2_32(WidenWidth / MemVTWidth) &&
         (MemVTWidth <= Width ||