[llvm] [SLP]Support minbitwidth analisys for buildvector nodes. (PR #88504)

[Simon Pilgrim via llvm-commits]

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@@ -8175,6 +8178,48 @@ class BoUpSLP::ShuffleCostEstimator : public BaseShuffleAnalysis {
     SmallVector<int> CommonMask(Mask.begin(), Mask.end());
     Value *V1 = P1.dyn_cast<Value *>(), *V2 = P2.dyn_cast<Value *>();
     unsigned CommonVF = Mask.size();
+    InstructionCost ExtraCost = 0;
+    auto GetNodeMinBWAffectedCost = [&](const TreeEntry &E,
+                                        unsigned VF) -> InstructionCost {
+      if (E.State == TreeEntry::NeedToGather && allConstant(E.Scalars))
+        return TTI::TCC_Free;
+      Type *EScalarTy = E.Scalars.front()->getType();
+      bool IsSigned = true;
+      if (auto It = R.MinBWs.find(&E); It != R.MinBWs.end()) {
+        EScalarTy = IntegerType::get(EScalarTy->getContext(), It->second.first);
+        IsSigned = It->second.second;
+      }
+      if (EScalarTy != ScalarTy) {
+        unsigned CastOpcode = Instruction::Trunc;
+        unsigned DstSz = R.DL->getTypeSizeInBits(ScalarTy);
+        unsigned SrcSz = R.DL->getTypeSizeInBits(EScalarTy);
+        if (DstSz > SrcSz)
+          CastOpcode = IsSigned ? Instruction::SExt : Instruction::ZExt;
+        return TTI.getCastInstrCost(
+            CastOpcode, FixedVectorType::get(ScalarTy, VF),
+            FixedVectorType::get(EScalarTy, VF), TTI::CastContextHint::None,
+            TTI::TCK_RecipThroughput);
+      }
+      return TTI::TCC_Free;
+    };
+    auto GetValueMinBWAffectedCost = [&](const Value *V) -> InstructionCost {
+      if (isa<Constant>(V))
+        return TTI::TCC_Free;
+      auto *VecTy = cast<VectorType>(V->getType());
+      Type *EScalarTy = VecTy->getElementType();
+      if (EScalarTy != ScalarTy) {
+        bool IsSigned = !isKnownNonNegative(V, SimplifyQuery(*R.DL));
+        unsigned CastOpcode = Instruction::Trunc;
+        unsigned DstSz = R.DL->getTypeSizeInBits(ScalarTy);
+        unsigned SrcSz = R.DL->getTypeSizeInBits(EScalarTy);
+        if (DstSz > SrcSz)
+          CastOpcode = IsSigned ? Instruction::SExt : Instruction::ZExt;
+        return TTI.getCastInstrCost(
+            CastOpcode, VectorType::get(ScalarTy, VecTy->getElementCount()),
+            VecTy, TTI::CastContextHint::None, TTI::TCK_RecipThroughput);
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RKSimon wrote:

Should CostKind be hard coded like this?

https://github.com/llvm/llvm-project/pull/88504