[RISCV] Lower insert_vector_elt on zvfhmin/zvfbfmin

This is the dual of #110144, but doesn't handle the case when the scalar type is illegal i.e. no zfhmin/zfbfmin. It looks like softening isn't yet implemented for insert_vector_elt operands and it will crash during type legalization, so I've left that configuration out of the tests.

Author: lukel97

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -1076,9 +1076,10 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
       setOperationAction({ISD::SINT_TO_FP, ISD::UINT_TO_FP, ISD::VP_SINT_TO_FP,
                           ISD::VP_UINT_TO_FP},
                          VT, Custom);
-      setOperationAction({ISD::CONCAT_VECTORS, ISD::INSERT_SUBVECTOR,
-                          ISD::EXTRACT_SUBVECTOR, ISD::VECTOR_DEINTERLEAVE,
-                          ISD::VECTOR_INTERLEAVE, ISD::VECTOR_REVERSE},
+      setOperationAction({ISD::INSERT_VECTOR_ELT, ISD::CONCAT_VECTORS,
+                          ISD::INSERT_SUBVECTOR, ISD::EXTRACT_SUBVECTOR,
+                          ISD::VECTOR_DEINTERLEAVE, ISD::VECTOR_INTERLEAVE,
+                          ISD::VECTOR_REVERSE},
                          VT, Custom);
       MVT EltVT = VT.getVectorElementType();
       if (isTypeLegal(EltVT))
@@ -8756,8 +8757,10 @@ SDValue RISCVTargetLowering::lowerINSERT_VECTOR_ELT(SDValue Op,
                                                     SelectionDAG &DAG) const {
   SDLoc DL(Op);
   MVT VecVT = Op.getSimpleValueType();
+  MVT XLenVT = Subtarget.getXLenVT();
   SDValue Vec = Op.getOperand(0);
   SDValue Val = Op.getOperand(1);
+  MVT ValVT = Val.getSimpleValueType();
   SDValue Idx = Op.getOperand(2);
 
   if (VecVT.getVectorElementType() == MVT::i1) {
@@ -8769,6 +8772,17 @@ SDValue RISCVTargetLowering::lowerINSERT_VECTOR_ELT(SDValue Op,
     return DAG.getNode(ISD::TRUNCATE, DL, VecVT, Vec);
   }
 
+  if ((ValVT == MVT::f16 && !Subtarget.hasVInstructionsF16()) ||
+      ValVT == MVT::bf16) {
+    // If we don't have vfmv.s.f for f16/bf16, insert into fmv.x.h first
+    MVT IntVT = VecVT.changeTypeToInteger();
+    // SDValue IntVal = DAG.getBitcast(IntVT.getVectorElementType(), Val);
+    SDValue IntInsert = DAG.getNode(
+        ISD::INSERT_VECTOR_ELT, DL, IntVT, DAG.getBitcast(IntVT, Vec),
+        DAG.getNode(RISCVISD::FMV_X_ANYEXTH, DL, XLenVT, Val), Idx);
+    return DAG.getBitcast(VecVT, IntInsert);
+  }
+
   MVT ContainerVT = VecVT;
   // If the operand is a fixed-length vector, convert to a scalable one.
   if (VecVT.isFixedLengthVector()) {
@@ -8812,8 +8826,6 @@ SDValue RISCVTargetLowering::lowerINSERT_VECTOR_ELT(SDValue Op,
                         AlignedIdx);
   }
 
-  MVT XLenVT = Subtarget.getXLenVT();
-
   bool IsLegalInsert = Subtarget.is64Bit() || Val.getValueType() != MVT::i64;
   // Even i64-element vectors on RV32 can be lowered without scalar
   // legalization if the most-significant 32 bits of the value are not affected