[llvm] [ISel] Introduce llvm.clmul[rh] intrinsics (PR #168731)

[Craig Topper via llvm-commits]

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@@ -7121,6 +7121,34 @@ SDValue SelectionDAG::FoldConstantArithmetic(unsigned Opcode, const SDLoc &DL,
     }
   }
 
+  // Handle clmul special cases.
+  if (Opcode == ISD::CLMUL || Opcode == ISD::CLMULR || Opcode == ISD::CLMULH) {
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topperc wrote:

This doesn't need to be special. You can use the binops handling by adding to the switch in `FoldValue`

https://github.com/llvm/llvm-project/pull/168731