[llvm] [RISCV][CostModel] Correct the cost of some reductions (PR #118072)

[Philip Reames via llvm-commits]

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@@ -1470,27 +1470,27 @@ RISCVTTIImpl::getMinMaxReductionCost(Intrinsic::ID IID, VectorType *Ty,
     llvm_unreachable("Unsupported intrinsic");
   case Intrinsic::smax:
     SplitOp = RISCV::VMAX_VV;
-    Opcodes = {RISCV::VMV_S_X, RISCV::VREDMAX_VS, RISCV::VMV_X_S};
+    Opcodes = {RISCV::VREDMAX_VS, RISCV::VMV_X_S};
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preames wrote:

Oh, so we only removed it for the ones where the start wasn't required.  I hadn't noticed that e.g. ADD wasn't changed.  Make sense - though the comment could definitely be clearer on this point.

https://github.com/llvm/llvm-project/pull/118072