[llvm] [SLP] Improve cost model for i1 select-as-or/and patterns (PR #188572)

[Alexey Bataev via llvm-commits]

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@@ -15999,19 +15999,40 @@ BoUpSLP::getEntryCost(const TreeEntry *E, ArrayRef<Value *> VectorizedVals,
       CmpPredicate CurrentPred = ScalarTy->isFloatingPointTy()
                                      ? CmpInst::BAD_FCMP_PREDICATE
                                      : CmpInst::BAD_ICMP_PREDICATE;
+      Value *LHS = nullptr, *RHS = nullptr;
       auto MatchCmp = m_Cmp(CurrentPred, m_Value(), m_Value());
-      if ((!match(VI, m_Select(MatchCmp, m_Value(), m_Value())) &&
-           !match(VI, MatchCmp)) ||
+      bool IsSelect = ShuffleOrOp == Instruction::Select &&
+                      match(VI, m_Select(MatchCmp, m_Value(LHS), m_Value(RHS)));
+      if ((!IsSelect && !match(VI, MatchCmp)) ||
           (CurrentPred != static_cast<CmpInst::Predicate>(VecPred) &&
            CurrentPred != static_cast<CmpInst::Predicate>(SwappedVecPred)))
         VecPred = SwappedVecPred = ScalarTy->isFloatingPointTy()
                                        ? CmpInst::BAD_FCMP_PREDICATE
                                        : CmpInst::BAD_ICMP_PREDICATE;
 
-      InstructionCost ScalarCost = TTI->getCmpSelInstrCost(
-          E->getOpcode(), OrigScalarTy, Builder.getInt1Ty(), CurrentPred,
-          CostKind, getOperandInfo(VI->getOperand(0)),
-          getOperandInfo(VI->getOperand(1)), VI);
+      // Check if operands are of i1 types, like a condition expression.
+      InstructionCost ScalarCost = InstructionCost::getInvalid();
+      if (IsSelect && LHS->getType() == VI->getOperand(0)->getType()) {
+        assert(LHS->getType() == RHS->getType() &&
+               "Expected same type for LHS/RHS");
+        // select i1 v, i1 true, i1 b -> or i1 v, i1 b
+        if (match(LHS, m_One())) {
+          ScalarCost = TTI->getArithmeticInstrCost(
+              Instruction::Or, LHS->getType(), CostKind,
+              getOperandInfo(VI->getOperand(0)), getOperandInfo(RHS));
+        } else if (match(RHS, m_Zero())) {
+          // select i1 v, i1 b, i1 false -> and i1 v, i1 b
+          ScalarCost = TTI->getArithmeticInstrCost(
+              Instruction::And, LHS->getType(), CostKind,
+              getOperandInfo(VI->getOperand(0)), getOperandInfo(LHS));
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alexey-bataev wrote:

Nope, need to get info for condition (operand 0) and LHS (operand 1)

https://github.com/llvm/llvm-project/pull/188572