[NFC][ScalarEvolution] Fix typo in getRangeForAffineAR and getRangeViaFactoring

[zhongduo]

Summary

Simple typo fix in ScalarEvolution.h. The AddRec is {start, +, step} rather than {start, +, stop}. The definition in cpp file has the right name.

[xgupta]

I think this patch needs a ping, so a ping!

[mkazantsev]

Indeed. :) Thanks.

[xgupta]

committed in https://reviews.llvm.org/rG0091e913ebfac1ec4a5185cc16e3eb7549149f91.

llvm/include/llvm/Analysis/ScalarEvolution.h

const ConstantRange &setRange(const SCEV *S, RangeSignHint Hint,
     return Pair.first->second;
   }
 
   /// Determine the range for a particular SCEV.
   /// NOTE: This returns a reference to an entry in a cache. It must be
   /// copied if its needed for longer.
   const ConstantRange &getRangeRef(const SCEV *S, RangeSignHint Hint);
 
-  /// Determines the range for the affine SCEVAddRecExpr {\p Start,+,\p Stop}.
+  /// Determines the range for the affine SCEVAddRecExpr {\p Start,+,\p Step}.
   /// Helper for \c getRange.
-  ConstantRange getRangeForAffineAR(const SCEV *Start, const SCEV *Stop,
+  ConstantRange getRangeForAffineAR(const SCEV *Start, const SCEV *Step,
                                     const SCEV *MaxBECount, unsigned BitWidth);
 
   /// Try to compute a range for the affine SCEVAddRecExpr {\p Start,+,\p
-  /// Stop} by "factoring out" a ternary expression from the add recurrence.
+  /// Step} by "factoring out" a ternary expression from the add recurrence.
   /// Helper called by \c getRange.
-  ConstantRange getRangeViaFactoring(const SCEV *Start, const SCEV *Stop,
+  ConstantRange getRangeViaFactoring(const SCEV *Start, const SCEV *Step,
                                      const SCEV *MaxBECount, unsigned BitWidth);
 
   /// We know that there is no SCEV for the specified value.  Analyze the
   /// expression.
   const SCEV *createSCEV(Value *V);
 
   /// Provide the special handling we need to analyze PHI SCEVs.
   const SCEV *createNodeForPHI(PHINode *PN);