[SimplifyIndVar][NFC] Refactor Binary Operator's strengthen

[aleksandr.popov]

Summary

Extract complex logic of Binary Operator's strengthen to a separate
method in order to reuse it

[mkazantsev]

LG

llvm/lib/Transforms/Utils/SimplifyIndVar.cpp

public:
     bool makeIVComparisonInvariant(ICmpInst *ICmp, Instruction *IVOperand);
     void eliminateIVComparison(ICmpInst *ICmp, Instruction *IVOperand);
     void simplifyIVRemainder(BinaryOperator *Rem, Instruction *IVOperand,
                              bool IsSigned);
     void replaceRemWithNumerator(BinaryOperator *Rem);
     void replaceRemWithNumeratorOrZero(BinaryOperator *Rem);
     void replaceSRemWithURem(BinaryOperator *Rem);
     bool eliminateSDiv(BinaryOperator *SDiv);
+    bool strengthenBinaryOp(BinaryOperator *BO, Instruction *IVOperand);
     bool strengthenOverflowingOperation(BinaryOperator *OBO,
                                         Instruction *IVOperand);
     bool strengthenRightShift(BinaryOperator *BO, Instruction *IVOperand);
   };
 }
 
 /// Find a point in code which dominates all given instructions. We can safely
 /// assume that, whatever fact we can prove at the found point, this fact is
bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
   SE->forgetValue(UseInst);
   UseInst->replaceAllUsesWith(IVOperand);
   ++NumElimIdentity;
   Changed = true;
   DeadInsts.emplace_back(UseInst);
   return true;
 }
 
+bool SimplifyIndvar::strengthenBinaryOp(BinaryOperator *BO,
+                                        Instruction *IVOperand) {
+  return (isa<OverflowingBinaryOperator>(BO) &&
+          strengthenOverflowingOperation(BO, IVOperand)) ||
+         (isa<ShlOperator>(BO) && strengthenRightShift(BO, IVOperand));
+}
+
 /// Annotate BO with nsw / nuw if it provably does not signed-overflow /
 /// unsigned-overflow.  Returns true if anything changed, false otherwise.
 bool SimplifyIndvar::strengthenOverflowingOperation(BinaryOperator *BO,
                                                     Instruction *IVOperand) {
   auto Flags = SE->getStrengthenedNoWrapFlagsFromBinOp(
       cast<OverflowingBinaryOperator>(BO));
 
   if (!Flags)
if (!IVOperand)
       continue;
 
     if (eliminateIVUser(UseInst, IVOperand)) {
       pushIVUsers(IVOperand, L, Simplified, SimpleIVUsers);
       continue;
     }
 
     if (BinaryOperator *BO = dyn_cast<BinaryOperator>(UseInst)) {
-      if ((isa<OverflowingBinaryOperator>(BO) &&
-           strengthenOverflowingOperation(BO, IVOperand)) ||
-          (isa<ShlOperator>(BO) && strengthenRightShift(BO, IVOperand))) {
+      if (strengthenBinaryOp(BO, IVOperand)) {
         // re-queue uses of the now modified binary operator and fall
         // through to the checks that remain.
         pushIVUsers(IVOperand, L, Simplified, SimpleIVUsers);
       }
     }
 
     // Try to use integer induction for FPToSI of float induction directly.
     if (replaceFloatIVWithIntegerIV(UseInst)) {