[VectorCombine] Fix invalid shuffle cost argument of foldShuffleOfSelects

In the previous code, it specified the destination vector as
the getShuffleCost argument. Because the shuffle mask specifies
the indices of the two vectors specified as elements, the maximum
value is twice the size of the source vector. This causes a problem
if the destination vector is smaller than the source vector and
specify an index in the mask that exceeds the size of the destination
vector.

Fix the problem by correcting the previous code, which was using
wrong argument in the Cost calculation.

Fixed #130250

Author: ParkHanbum

llvm/lib/Transforms/Vectorize/VectorCombine.cpp

@@ -2037,7 +2037,6 @@ bool VectorCombine::foldShuffleOfSelects(Instruction &I) {
                      m_Mask(Mask))))
     return false;
 
-  auto *DstVecTy = dyn_cast<FixedVectorType>(I.getType());
   auto *C1VecTy = dyn_cast<FixedVectorType>(C1->getType());
   auto *C2VecTy = dyn_cast<FixedVectorType>(C2->getType());
   if (!C1VecTy || !C2VecTy || C1VecTy != C2VecTy)
@@ -2051,24 +2050,26 @@ bool VectorCombine::foldShuffleOfSelects(Instruction &I) {
        (SI0FOp->getFastMathFlags() != SI1FOp->getFastMathFlags())))
     return false;
 
+  auto *SrcVecTy = dyn_cast<FixedVectorType>(T1->getType());
+  auto *DstVecTy = dyn_cast<FixedVectorType>(I.getType());
   auto SK = TargetTransformInfo::SK_PermuteTwoSrc;
   auto SelOp = Instruction::Select;
   InstructionCost OldCost = TTI.getCmpSelInstrCost(
-      SelOp, T1->getType(), C1VecTy, CmpInst::BAD_ICMP_PREDICATE, CostKind);
-  OldCost += TTI.getCmpSelInstrCost(SelOp, T2->getType(), C2VecTy,
+      SelOp, DstVecTy, C1VecTy, CmpInst::BAD_ICMP_PREDICATE, CostKind);
+  OldCost += TTI.getCmpSelInstrCost(SelOp, DstVecTy, C2VecTy,
                                     CmpInst::BAD_ICMP_PREDICATE, CostKind);
-  OldCost += TTI.getShuffleCost(SK, DstVecTy, Mask, CostKind, 0, nullptr,
+  OldCost += TTI.getShuffleCost(SK, SrcVecTy, Mask, CostKind, 0, nullptr,
                                 {I.getOperand(0), I.getOperand(1)}, &I);
 
-  auto *C1C2VecTy = cast<FixedVectorType>(
-      toVectorTy(Type::getInt1Ty(I.getContext()), DstVecTy->getNumElements()));
   InstructionCost NewCost =
-      TTI.getShuffleCost(SK, C1C2VecTy, Mask, CostKind, 0, nullptr, {C1, C2});
+      TTI.getShuffleCost(SK, C1VecTy, Mask, CostKind, 0, nullptr, {C1, C2});
   NewCost +=
-      TTI.getShuffleCost(SK, DstVecTy, Mask, CostKind, 0, nullptr, {T1, T2});
+      TTI.getShuffleCost(SK, SrcVecTy, Mask, CostKind, 0, nullptr, {T1, T2});
   NewCost +=
-      TTI.getShuffleCost(SK, DstVecTy, Mask, CostKind, 0, nullptr, {F1, F2});
-  NewCost += TTI.getCmpSelInstrCost(SelOp, DstVecTy, DstVecTy,
+      TTI.getShuffleCost(SK, SrcVecTy, Mask, CostKind, 0, nullptr, {F1, F2});
+  auto *C1C2ShuffledVecTy = cast<FixedVectorType>(
+      toVectorTy(Type::getInt1Ty(I.getContext()), DstVecTy->getNumElements()));
+  NewCost += TTI.getCmpSelInstrCost(SelOp, DstVecTy, C1C2ShuffledVecTy,
                                     CmpInst::BAD_ICMP_PREDICATE, CostKind);
 
   LLVM_DEBUG(dbgs() << "Found a shuffle feeding two selects: " << I