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

[Simon Pilgrim via llvm-commits]

================
@@ -15999,23 +15999,46 @@ 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))) ||
+           match(VI, m_Select(m_Value(), 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(ShuffleOrOp == Instruction::Select ? 1 : 0)),
-          getOperandInfo(
-              VI->getOperand(ShuffleOrOp == Instruction::Select ? 2 : 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
----------------
RKSimon wrote:

this isn't undef safe - https://alive2.llvm.org/ce/z/hHLNL4

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