[clang] [llvm] [RISCV][P-ext] Fold an add of a multiply-parts product into the accumulate form (PR #222748)

[via cfe-commits]

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@@ -18510,6 +18551,30 @@ static SDValue combineAddMulh(SDNode *N, SelectionDAG &DAG,
   return DAG.getNode(RISCVISD::MULHSU, DL, VT, X, Mulh.getOperand(1));
 }
 
+// Fold an add of a multiply-parts product into the accumulating form.
+static SDValue combineAddMulParts(SDNode *N, SelectionDAG &DAG,
+                                  const RISCVSubtarget &Subtarget) {
+  if (!Subtarget.hasStdExtP())
+    return SDValue();
+
+  for (unsigned I = 0; I != 2; ++I) {
+    SDValue Mul = N->getOperand(I);
+    if (Mul.getOpcode() != ISD::INTRINSIC_WO_CHAIN || !Mul.hasOneUse())
+      continue;
+    Intrinsic::ID AccId =
+        getRVPMulPartsAccIntrinsic(Mul.getConstantOperandVal(0));
+    if (AccId == Intrinsic::not_intrinsic)
+      continue;
+
+    SDLoc DL(N);
+    return DAG.getNode(ISD::INTRINSIC_WO_CHAIN, DL, N->getValueType(0),
+                       DAG.getTargetConstant(AccId, DL, MVT::i32),
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sihuan wrote:

Fixed.

https://github.com/llvm/llvm-project/pull/222748