[llvm] [RISCV][CostModel] Add cost for @llvm.experimental.vp.splice (PR #122223)

[Craig Topper via llvm-commits]

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@@ -1235,6 +1235,33 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
                                                   : RISCV::VMV_V_X,
                                               LT.second, CostKind);
   }
+  case Intrinsic::experimental_vp_splice: {
+    auto LT = getTypeLegalizationCost(RetTy);
+    SmallVector<unsigned, 3> Opcodes;
+    Value *ImmValue = *(ICA.getInst()->arg_begin() + 2);
+    auto *Imm = dyn_cast<ConstantInt>(ImmValue);
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topperc wrote:

If you use `dyn_cast`, you must check the result for null before dereferencing. If can't be null, use `cast`.

https://github.com/llvm/llvm-project/pull/122223