[llvm] [SelectionDAG][RISCV] (add (vscale * C0), (vscale * C1)) to (vscale * (C0 + C1)) in getNode. (PR #144565)

[Philip Reames via llvm-commits]

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@@ -7377,6 +7377,12 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
     if ((Opcode == ISD::ADD || Opcode == ISD::SUB) &&
         VT.getScalarType() == MVT::i1)
       return getNode(ISD::XOR, DL, VT, N1, N2);
+    if (Opcode == ISD::ADD && N1.getOpcode() == ISD::VSCALE &&
+        N2.getOpcode() == ISD::VSCALE) {
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preames wrote:

What's the wrap behavior here?  Do we need to check the nsw/nuw on the ADD?

https://github.com/llvm/llvm-project/pull/144565