[Transforms] Remove FactorOutConstant to fix -Wunneeded-internal-declaration (NFC)

/Users/jiefu/llvm-project/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp:293:13: error: function 'FactorOutConstant' is not needed and will not be emitted [-Werror,-Wunneeded-internal-declaration]
static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder,
            ^
1 error generated.

Author: DamonFool

llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp

@@ -286,79 +286,6 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
   return BO;
 }
 
-/// FactorOutConstant - Test if S is divisible by Factor, using signed
-/// division. If so, update S with Factor divided out and return true.
-/// S need not be evenly divisible if a reasonable remainder can be
-/// computed.
-static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder,
-                              const SCEV *Factor, ScalarEvolution &SE,
-                              const DataLayout &DL) {
-  // Everything is divisible by one.
-  if (Factor->isOne())
-    return true;
-
-  // x/x == 1.
-  if (S == Factor) {
-    S = SE.getConstant(S->getType(), 1);
-    return true;
-  }
-
-  // For a Constant, check for a multiple of the given factor.
-  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
-    // 0/x == 0.
-    if (C->isZero())
-      return true;
-    // Check for divisibility.
-    if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) {
-      ConstantInt *CI =
-          ConstantInt::get(SE.getContext(), C->getAPInt().sdiv(FC->getAPInt()));
-      // If the quotient is zero and the remainder is non-zero, reject
-      // the value at this scale. It will be considered for subsequent
-      // smaller scales.
-      if (!CI->isZero()) {
-        const SCEV *Div = SE.getConstant(CI);
-        S = Div;
-        Remainder = SE.getAddExpr(
-            Remainder, SE.getConstant(C->getAPInt().srem(FC->getAPInt())));
-        return true;
-      }
-    }
-  }
-
-  // In a Mul, check if there is a constant operand which is a multiple
-  // of the given factor.
-  if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
-    // Size is known, check if there is a constant operand which is a multiple
-    // of the given factor. If so, we can factor it.
-    if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor))
-      if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
-        if (!C->getAPInt().srem(FC->getAPInt())) {
-          SmallVector<const SCEV *, 4> NewMulOps(M->operands());
-          NewMulOps[0] = SE.getConstant(C->getAPInt().sdiv(FC->getAPInt()));
-          S = SE.getMulExpr(NewMulOps);
-          return true;
-        }
-  }
-
-  // In an AddRec, check if both start and step are divisible.
-  if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
-    const SCEV *Step = A->getStepRecurrence(SE);
-    const SCEV *StepRem = SE.getConstant(Step->getType(), 0);
-    if (!FactorOutConstant(Step, StepRem, Factor, SE, DL))
-      return false;
-    if (!StepRem->isZero())
-      return false;
-    const SCEV *Start = A->getStart();
-    if (!FactorOutConstant(Start, Remainder, Factor, SE, DL))
-      return false;
-    S = SE.getAddRecExpr(Start, Step, A->getLoop(),
-                         A->getNoWrapFlags(SCEV::FlagNW));
-    return true;
-  }
-
-  return false;
-}
-
 /// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs
 /// is the number of SCEVAddRecExprs present, which are kept at the end of
 /// the list.