[llvm] [RISCV][CostModel] Updates reduction and shuffle cost (PR #77342)

[Wang Pengcheng via llvm-commits]

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@@ -1358,19 +1363,53 @@ RISCVTTIImpl::getMinMaxReductionCost(Intrinsic::ID IID, VectorType *Ty,
     return BaseT::getMinMaxReductionCost(IID, Ty, FMF, CostKind);
 
   std::pair<InstructionCost, MVT> LT = getTypeLegalizationCost(Ty);
-  if (Ty->getElementType()->isIntegerTy(1))
-    // vcpop sequences, see vreduction-mask.ll.  umax, smin actually only
-    // cost 2, but we don't have enough info here so we slightly over cost.
-    return (LT.first - 1) + 3;
+  std::array<unsigned, 3> Opcodes;
+  if (Ty->getElementType()->isIntegerTy(1)) {
+    // vcpop sequences, see vreduction-mask.ll.
+    if ((IID == Intrinsic::umax) || (IID == Intrinsic::smin))
+      Opcodes = {RISCV::VMNAND_MM, RISCV::VCPOP_M, RISCV::SLT};
+    else
+      Opcodes = {RISCV::VCPOP_M, RISCV::SLT};
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wangpc-pp wrote:

The third element of `Opcodes` will be 0? The cost is not right then.

https://github.com/llvm/llvm-project/pull/77342