[IVDescriptors] Remove getConsecutiveDirection (NFC)

The last use of the function was removed on Sep 18, 2016 in commit
5f8cc0c.

The function was later moved to llvm/lib/Analysis/IVDescriptors.cpp on
Sep 12, 2018 in commit 7e98d69.

Author: kazutakahirata

llvm/include/llvm/Analysis/IVDescriptors.h

@@ -268,12 +268,6 @@ class InductionDescriptor {
   /// Default constructor - creates an invalid induction.
   InductionDescriptor() = default;
 
-  /// Get the consecutive direction. Returns:
-  ///   0 - unknown or non-consecutive.
-  ///   1 - consecutive and increasing.
-  ///  -1 - consecutive and decreasing.
-  int getConsecutiveDirection() const;
-
   Value *getStartValue() const { return StartValue; }
   InductionKind getKind() const { return IK; }
   const SCEV *getStep() const { return Step; }

llvm/lib/Analysis/IVDescriptors.cpp

@@ -927,13 +927,6 @@ InductionDescriptor::InductionDescriptor(Value *Start, InductionKind K,
   }
 }
 
-int InductionDescriptor::getConsecutiveDirection() const {
-  ConstantInt *ConstStep = getConstIntStepValue();
-  if (ConstStep && (ConstStep->isOne() || ConstStep->isMinusOne()))
-    return ConstStep->getSExtValue();
-  return 0;
-}
-
 ConstantInt *InductionDescriptor::getConstIntStepValue() const {
   if (isa<SCEVConstant>(Step))
     return dyn_cast<ConstantInt>(cast<SCEVConstant>(Step)->getValue());