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

[Elvis Wang via llvm-commits]

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@@ -1497,6 +1497,33 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
                           cast<VectorType>(ICA.getArgTypes()[0]), {}, CostKind,
                           0, cast<VectorType>(ICA.getReturnType()));
   }
+  case Intrinsic::fptoui_sat:
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ElvisWang123 wrote:

I think it is not only missing the scalarization for the source type, the cost of `fptoui_sat` is much lower than expect.

This can be implemented in `BasicTTI::getIntrinsicInstrCost()`. But when using type-based query it will try to get cost from `BasicTTI::getTypeBasedIntrinsicInstrCost()` which will return the cost different from the value-based query.

IIUC #97463 make the precedent that cost of intrinsics in `getTypeBasedIntrinsicInstrCost()` and not implemented before https://github.com/llvm/llvm-project/blob/a3201ce9e114aa2ecd66e525607093e4dff2f574/llvm/include/llvm/CodeGen/BasicTTIImpl.h#L2511  should be handled by target.



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