[SCEV][NFC] Introduce API for mass forgetMemoizedResults query

This patch changes signature of forgetMemoizedResults to be able to work with
multiple SCEVs. Usage will come in follow-ups. We also plan to optimize it in the
future to work faster than individual invalidation updates. Should not change
behavior in any sense.

Split-off from D111602.

Differential Revision: https://reviews.llvm.org/D112293
Reviewed By: reames

Author: xortator

llvm/include/llvm/Analysis/ScalarEvolution.h

@@ -1888,8 +1888,11 @@ class ScalarEvolution {
   bool splitBinaryAdd(const SCEV *Expr, const SCEV *&L, const SCEV *&R,
                       SCEV::NoWrapFlags &Flags);
 
-  /// Drop memoized information computed for S.
-  void forgetMemoizedResults(const SCEV *S);
+  /// Drop memoized information for all \p SCEVs.
+  void forgetMemoizedResults(ArrayRef<const SCEV *> SCEVs);
+
+  /// Helper for forgetMemoizedResults.
+  void forgetMemoizedResultsImpl(const SCEV *S);
 
   /// Return an existing SCEV for V if there is one, otherwise return nullptr.
   const SCEV *getExistingSCEV(Value *V);

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -12746,8 +12746,12 @@ bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
   return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; });
 }
 
-void
-ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
+void ScalarEvolution::forgetMemoizedResults(ArrayRef<const SCEV *> SCEVs) {
+  for (auto *S : SCEVs)
+    forgetMemoizedResultsImpl(S);
+}
+
+void ScalarEvolution::forgetMemoizedResultsImpl(const SCEV *S) {
   ValuesAtScopes.erase(S);
   LoopDispositions.erase(S);
   BlockDispositions.erase(S);