[Analysis] Remove isArithmeticRecurrenceKind

The last use was removed on Jul 30, 2021 in commit
9d35594.

Author: kazutakahirata

llvm/include/llvm/Analysis/IVDescriptors.h

@@ -215,9 +215,6 @@ class RecurrenceDescriptor {
   /// Returns true if the recurrence kind is a floating point kind.
   static bool isFloatingPointRecurrenceKind(RecurKind Kind);
 
-  /// Returns true if the recurrence kind is an arithmetic kind.
-  static bool isArithmeticRecurrenceKind(RecurKind Kind);
-
   /// Returns true if the recurrence kind is an integer min/max kind.
   static bool isIntMinMaxRecurrenceKind(RecurKind Kind) {
     return Kind == RecurKind::UMin || Kind == RecurKind::UMax ||

llvm/lib/Analysis/IVDescriptors.cpp

@@ -63,20 +63,6 @@ bool RecurrenceDescriptor::isFloatingPointRecurrenceKind(RecurKind Kind) {
   return (Kind != RecurKind::None) && !isIntegerRecurrenceKind(Kind);
 }
 
-bool RecurrenceDescriptor::isArithmeticRecurrenceKind(RecurKind Kind) {
-  switch (Kind) {
-  default:
-    break;
-  case RecurKind::Add:
-  case RecurKind::Mul:
-  case RecurKind::FAdd:
-  case RecurKind::FMul:
-  case RecurKind::FMulAdd:
-    return true;
-  }
-  return false;
-}
-
 /// Determines if Phi may have been type-promoted. If Phi has a single user
 /// that ANDs the Phi with a type mask, return the user. RT is updated to
 /// account for the narrower bit width represented by the mask, and the AND