[PATCH] D112294: [SCEV][NFC] Win some compile time from mass forgetMemoizedResults

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
mkazantsev added reviewers: reames, lebedev.ri, nikic, efriedma.
Herald added subscribers: javed.absar, hiraditya.
mkazantsev requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Mass forgetMemoizedResults can be done more efficiently than bunch
of individual invocations of helper because we can traverse maps being
updated just once, rather than doing this for each invidivual SCEV.

Should be NFC and supposedly improves compile time.


https://reviews.llvm.org/D112294

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp


Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -12834,42 +12834,43 @@
 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);
-  UnsignedRanges.erase(S);
-  SignedRanges.erase(S);
-  ExprValueMap.erase(S);
-  HasRecMap.erase(S);
-  MinTrailingZerosCache.erase(S);
-
+  SmallPtrSet<const SCEV *, 8> ToForget(SCEVs.begin(), SCEVs.end());
   for (auto I = PredicatedSCEVRewrites.begin();
        I != PredicatedSCEVRewrites.end();) {
     std::pair<const SCEV *, const Loop *> Entry = I->first;
-    if (Entry.first == S)
+    if (ToForget.count(Entry.first))
       PredicatedSCEVRewrites.erase(I++);
     else
       ++I;
   }
 
-  auto RemoveSCEVFromBackedgeMap =
-      [S](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
+  auto RemoveSCEVFromBackedgeMap = [this, &ToForget](
+      DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
         for (auto I = Map.begin(), E = Map.end(); I != E;) {
           BackedgeTakenInfo &BEInfo = I->second;
-          if (BEInfo.hasOperand(S))
+          if (any_of(ToForget,
+                     [&BEInfo](const SCEV *S) { return BEInfo.hasOperand(S); }))
             Map.erase(I++);
           else
             ++I;
         }
-      };
+  };
 
   RemoveSCEVFromBackedgeMap(BackedgeTakenCounts);
   RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
 }
 
+void ScalarEvolution::forgetMemoizedResultsImpl(const SCEV *S) {
+  ValuesAtScopes.erase(S);
+  LoopDispositions.erase(S);
+  BlockDispositions.erase(S);
+  UnsignedRanges.erase(S);
+  SignedRanges.erase(S);
+  ExprValueMap.erase(S);
+  HasRecMap.erase(S);
+  MinTrailingZerosCache.erase(S);
+}
+
 void
 ScalarEvolution::getUsedLoops(const SCEV *S,
                               SmallPtrSetImpl<const Loop *> &LoopsUsed) {


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