[PATCH] D111602: [SCEV][NFC] Tackle quadratic CT consumption in forgetValue

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev updated this revision to Diff 378886.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D111602/new/

https://reviews.llvm.org/D111602

Files:
  llvm/include/llvm/Analysis/ScalarEvolution.h
  llvm/lib/Analysis/ScalarEvolution.cpp


Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -7557,8 +7557,7 @@
 
     auto LoopUsersItr = LoopUsers.find(CurrL);
     if (LoopUsersItr != LoopUsers.end()) {
-      for (auto *S : LoopUsersItr->second)
-        forgetMemoizedResults(S);
+      forgetMemoizedResults(LoopUsersItr->second);
       LoopUsers.erase(LoopUsersItr);
     }
 
@@ -7604,6 +7603,7 @@
   Worklist.push_back(I);
 
   SmallPtrSet<Instruction *, 8> Visited;
+  SmallVector<const SCEV *, 8> ToForget;
   while (!Worklist.empty()) {
     I = Worklist.pop_back_val();
     if (!Visited.insert(I).second)
@@ -7613,13 +7613,14 @@
       ValueExprMap.find_as(static_cast<Value *>(I));
     if (It != ValueExprMap.end()) {
       eraseValueFromMap(It->first);
-      forgetMemoizedResults(It->second);
+      ToForget.push_back(It->second);
       if (PHINode *PN = dyn_cast<PHINode>(I))
         ConstantEvolutionLoopExitValue.erase(PN);
     }
 
     PushDefUseChildren(I, Worklist);
   }
+  forgetMemoizedResults(ToForget);
 }
 
 void ScalarEvolution::forgetLoopDispositions(const Loop *L) {
@@ -12807,10 +12808,18 @@
 }
 
 void ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
+  SmallVector<const SCEV *> ToForget;
+  ToForget.push_back(S);
+  forgetMemoizedResults(ToForget);
+}
+
+void ScalarEvolution::forgetMemoizedResults(ArrayRef<const SCEV *> SCEVs) {
   SmallPtrSet<const SCEV *, 16> Visited;
   SmallVector<const SCEV *, 16> Worklist;
-  Visited.insert(S);
-  Worklist.push_back(S);
+  for (auto *S : SCEVs)
+    if (Visited.insert(S).second)
+      Worklist.push_back(S);
+
   while (!Worklist.empty()) {
     const SCEV *Curr = Worklist.pop_back_val();
     auto Users = SCEVUsers.find(Curr);
Index: llvm/include/llvm/Analysis/ScalarEvolution.h
===================================================================
--- llvm/include/llvm/Analysis/ScalarEvolution.h
+++ llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -1889,6 +1889,9 @@
   /// Drop memoized information computed for S.
   void forgetMemoizedResults(const SCEV *S);
 
+  /// Drop memoized information for all \p SCEVs.
+  void forgetMemoizedResults(ArrayRef<const SCEV *> SCEVs);
+
   void forgetMemoizedResultsImpl(const SCEV *S);
 
   /// Return an existing SCEV for V if there is one, otherwise return nullptr.


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