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

[Matt Arsenault via llvm-commits]

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@@ -1497,6 +1497,36 @@ 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();
+
+    IntrinsicCostAttributes Attrs1(Intrinsic::minnum, SrcTy, {SrcTy, SrcTy});
+    Cost += getIntrinsicInstrCost(Attrs1, CostKind);
+    IntrinsicCostAttributes Attrs2(Intrinsic::maxnum, SrcTy, {SrcTy, SrcTy});
+    Cost += getIntrinsicInstrCost(Attrs2, CostKind);
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arsenm wrote:

We probably should be checking / using something other than minnum/maxnum here but I haven't thought too deeply about it 

https://github.com/llvm/llvm-project/pull/143655