[llvm] [IR][RISCV] Add llvm.vector.(de)interleave3/5/7 (PR #124825)

[Craig Topper via llvm-commits]

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@@ -555,6 +573,12 @@ static Type *DecodeFixedType(ArrayRef<Intrinsic::IITDescriptor> &Infos,
   case IITDescriptor::HalfVecArgument:
     return VectorType::getHalfElementsVectorType(
         cast<VectorType>(Tys[D.getArgumentNumber()]));
+  case IITDescriptor::OneThirdVecArgument:
+  case IITDescriptor::OneFifthVecArgument:
+  case IITDescriptor::OneSeventhVecArgument:
+    return VectorType::getOneNthElementsVectorType(
+        cast<VectorType>(Tys[D.getArgumentNumber()]),
+        3 + (D.Kind - IITDescriptor::OneThirdVecArgument) * 2);
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topperc wrote:

Add a static_assert to protect the assumption that OneThirdVecArgument/OneFifthVecArgument/OneSeventhVecArgument are contiguous

https://github.com/llvm/llvm-project/pull/124825