[llvm] Add `llvm.vector.partial.reduce.fadd` intrinsic (PR #159776)

[Sander de Smalen via llvm-commits]

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@@ -12062,21 +12062,27 @@ SDValue TargetLowering::expandPartialReduceMLA(SDNode *N,
       EVT::getVectorVT(*DAG.getContext(), AccVT.getVectorElementType(),
                        MulOpVT.getVectorElementCount());
 
-  unsigned ExtOpcLHS = N->getOpcode() == ISD::PARTIAL_REDUCE_UMLA
-                      ? ISD::ZERO_EXTEND
-                      : ISD::SIGN_EXTEND;
-  unsigned ExtOpcRHS = N->getOpcode() == ISD::PARTIAL_REDUCE_SMLA
-                      ? ISD::SIGN_EXTEND
-                      : ISD::ZERO_EXTEND;
+  unsigned ExtOpcLHS =
+      N->getOpcode() == ISD::PARTIAL_REDUCE_FMLA   ? ISD::FP_EXTEND
+      : N->getOpcode() == ISD::PARTIAL_REDUCE_UMLA ? ISD::ZERO_EXTEND
+                                                   : ISD::SIGN_EXTEND;
+  unsigned ExtOpcRHS =
+      N->getOpcode() == ISD::PARTIAL_REDUCE_FMLA   ? ISD::FP_EXTEND
+      : N->getOpcode() == ISD::PARTIAL_REDUCE_SMLA ? ISD::SIGN_EXTEND
+                                                   : ISD::ZERO_EXTEND;
 
   if (ExtMulOpVT != MulOpVT) {
     MulLHS = DAG.getNode(ExtOpcLHS, DL, ExtMulOpVT, MulLHS);
     MulRHS = DAG.getNode(ExtOpcRHS, DL, ExtMulOpVT, MulRHS);
   }
   SDValue Input = MulLHS;
   APInt ConstantOne;
-  if (!ISD::isConstantSplatVector(MulRHS.getNode(), ConstantOne) ||
-      !ConstantOne.isOne())
+  ConstantFPSDNode *C;
+  if (!(N->getOpcode() == ISD::PARTIAL_REDUCE_FMLA &&
+        (C = llvm::isConstOrConstSplatFP(MulRHS, false)) &&
+        C->isExactlyValue(1.0)) &&
+      !(ISD::isConstantSplatVector(MulRHS.getNode(), ConstantOne) &&
+        ConstantOne.isOne()))
     Input = DAG.getNode(ISD::MUL, DL, ExtMulOpVT, MulLHS, MulRHS);
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sdesmalen-arm wrote:

This can only work for integer types, so this is also missing test coverage?

https://github.com/llvm/llvm-project/pull/159776