[RISCV][TTI] Implement vector costs for llvm.fpto{u|s}i.sat(). (llvm#143655)

This patch implement vector costs for `llvm.fptoui.sat()` in RISCV TTI.

Author: ElvisWang123

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

@@ -1489,6 +1489,34 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
                           cast<VectorType>(ICA.getArgTypes()[0]), {}, CostKind,
                           0, cast<VectorType>(ICA.getReturnType()));
   }
+  case Intrinsic::fptoui_sat:
+  case Intrinsic::fptosi_sat: {
+    InstructionCost Cost = 0;
+    bool IsSigned = ICA.getID() == Intrinsic::fptosi_sat;
+    Type *SrcTy = ICA.getArgTypes()[0];
+
+    auto SrcLT = getTypeLegalizationCost(SrcTy);
+    auto DstLT = getTypeLegalizationCost(RetTy);
+    if (!SrcTy->isVectorTy())
+      break;
+
+    if (!SrcLT.first.isValid() || !DstLT.first.isValid())
+      return InstructionCost::getInvalid();
+
+    Cost +=
+        getCastInstrCost(IsSigned ? Instruction::FPToSI : Instruction::FPToUI,
+                         RetTy, SrcTy, TTI::CastContextHint::None, CostKind);
+
+    // Handle NaN.
+    // vmfne v0, v8, v8         # If v8[i] is NaN set v0[i] to 1.
+    // vmerge.vim v8, v8, 0, v0 # Convert NaN to 0.
+    Type *CondTy = RetTy->getWithNewBitWidth(1);
+    Cost += getCmpSelInstrCost(BinaryOperator::FCmp, SrcTy, CondTy,
+                               CmpInst::FCMP_UNO, CostKind);
+    Cost += getCmpSelInstrCost(BinaryOperator::Select, RetTy, CondTy,
+                               CmpInst::FCMP_UNO, CostKind);
+    return Cost;
+  }
   }
 
   if (ST->hasVInstructions() && RetTy->isVectorTy()) {