[llvm] [IR] Add llvm `clmul` intrinsic (PR #140301)

[Craig Topper via llvm-commits]

================
@@ -10348,6 +10348,7 @@ SDValue RISCVTargetLowering::LowerINTRINSIC_WO_CHAIN(SDValue Op,
     return DAG.getNode(RISCVISD::MOPRR, DL, XLenVT, Op.getOperand(1),
                        Op.getOperand(2), Op.getOperand(3));
   }
+  case Intrinsic::clmul:
----------------
topperc wrote:

We should not do that. We should add `clmul` to TargetSelectionDAG.td and add isel patterns to RISCVInstrInfoZb.td like

```
def : PatGprGpr<clmul, CLMUL>;
```

https://github.com/llvm/llvm-project/pull/140301