[RISCV] Remove mask size restriction on single source and dual src shuffle costing

Some callers pass in an empty mask to represent "unknown".  We should use the generic costs for these cases.  We can add VL=1 costing seperately if desired.

Author: preames

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

@@ -324,36 +324,33 @@ InstructionCost RISCVTTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
               return LT.first * getLMULCost(LT.second);
           }
         }
-
-        // vrgather + cost of generating the mask constant.
-        // We model this for an unknown mask with a single vrgather.
-        if (LT.first == 1 &&
-            (LT.second.getScalarSizeInBits() != 8 ||
-             LT.second.getVectorNumElements() <= 256)) {
-          VectorType *IdxTy = getVRGatherIndexType(LT.second, *ST, Tp->getContext());
-          InstructionCost IndexCost = getConstantPoolLoadCost(IdxTy, CostKind);
-          return IndexCost + getVRGatherVVCost(LT.second);
-        }
+      }
+      // vrgather + cost of generating the mask constant.
+      // We model this for an unknown mask with a single vrgather.
+      if (LT.second.isFixedLengthVector() && LT.first == 1 &&
+          (LT.second.getScalarSizeInBits() != 8 ||
+           LT.second.getVectorNumElements() <= 256)) {
+        VectorType *IdxTy = getVRGatherIndexType(LT.second, *ST, Tp->getContext());
+        InstructionCost IndexCost = getConstantPoolLoadCost(IdxTy, CostKind);
+        return IndexCost + getVRGatherVVCost(LT.second);
       }
       [[fallthrough]];
     }
     case TTI::SK_Transpose:
     case TTI::SK_PermuteTwoSrc: {
-      if (Mask.size() >= 2 && LT.second.isFixedLengthVector()) {
-        // 2 x (vrgather + cost of generating the mask constant) + cost of mask
-        // register for the second vrgather. We model this for an unknown
-        // (shuffle) mask.
-        if (LT.first == 1 &&
-            (LT.second.getScalarSizeInBits() != 8 ||
-             LT.second.getVectorNumElements() <= 256)) {
-          auto &C = Tp->getContext();
-          auto EC = Tp->getElementCount();
-          VectorType *IdxTy = getVRGatherIndexType(LT.second, *ST, C);
-          VectorType *MaskTy = VectorType::get(IntegerType::getInt1Ty(C), EC);
-          InstructionCost IndexCost = getConstantPoolLoadCost(IdxTy, CostKind);
-          InstructionCost MaskCost = getConstantPoolLoadCost(MaskTy, CostKind);
-          return 2 * IndexCost + 2 * getVRGatherVVCost(LT.second) + MaskCost;
-        }
+      // 2 x (vrgather + cost of generating the mask constant) + cost of mask
+      // register for the second vrgather. We model this for an unknown
+      // (shuffle) mask.
+      if (LT.second.isFixedLengthVector() && LT.first == 1 &&
+          (LT.second.getScalarSizeInBits() != 8 ||
+           LT.second.getVectorNumElements() <= 256)) {
+        auto &C = Tp->getContext();
+        auto EC = Tp->getElementCount();
+        VectorType *IdxTy = getVRGatherIndexType(LT.second, *ST, C);
+        VectorType *MaskTy = VectorType::get(IntegerType::getInt1Ty(C), EC);
+        InstructionCost IndexCost = getConstantPoolLoadCost(IdxTy, CostKind);
+        InstructionCost MaskCost = getConstantPoolLoadCost(MaskTy, CostKind);
+        return 2 * IndexCost + 2 * getVRGatherVVCost(LT.second) + MaskCost;
       }
       [[fallthrough]];
     }