[PATCH] D102796: [SCEV] Cache operands used in BEInfo

[Nikita Popov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG6300c37a461b: [SCEV] Cache operands used in BEInfo (NFC) (authored by nikic).

Changed prior to commit:
  https://reviews.llvm.org/D102796?vs=346525&id=347752#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D102796/new/

https://reviews.llvm.org/D102796

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
@@ -7392,18 +7392,8 @@
   return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue);
 }
 
-bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
-                                                    ScalarEvolution *SE) const {
-  if (getConstantMax() && getConstantMax() != SE->getCouldNotCompute() &&
-      SE->hasOperand(getConstantMax(), S))
-    return true;
-
-  for (auto &ENT : ExitNotTaken)
-    if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
-        SE->hasOperand(ENT.ExactNotTaken, S))
-      return true;
-
-  return false;
+bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S) const {
+  return Operands.contains(S);
 }
 
 ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
@@ -7445,6 +7435,19 @@
          "No point in having a non-constant max backedge taken count!");
 }
 
+class SCEVRecordOperands {
+  SmallPtrSetImpl<const SCEV *> &Operands;
+
+public:
+  SCEVRecordOperands(SmallPtrSetImpl<const SCEV *> &Operands)
+    : Operands(Operands) {}
+  bool follow(const SCEV *S) {
+    Operands.insert(S);
+    return true;
+  }
+  bool isDone() { return false; }
+};
+
 /// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
 /// computable exit into a persistent ExitNotTakenInfo array.
 ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
@@ -7473,6 +7476,14 @@
   assert((isa<SCEVCouldNotCompute>(ConstantMax) ||
           isa<SCEVConstant>(ConstantMax)) &&
          "No point in having a non-constant max backedge taken count!");
+
+  SCEVRecordOperands RecordOperands(Operands);
+  SCEVTraversal<SCEVRecordOperands> ST(RecordOperands);
+  if (!isa<SCEVCouldNotCompute>(ConstantMax))
+    ST.visitAll(ConstantMax);
+  for (auto &ENT : ExitNotTaken)
+    if (!isa<SCEVCouldNotCompute>(ENT.ExactNotTaken))
+      ST.visitAll(ENT.ExactNotTaken);
 }
 
 /// Compute the number of times the backedge of the specified loop will execute.
@@ -12627,7 +12638,7 @@
       [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
         for (auto I = Map.begin(), E = Map.end(); I != E;) {
           BackedgeTakenInfo &BEInfo = I->second;
-          if (BEInfo.hasOperand(S, this))
+          if (BEInfo.hasOperand(S))
             Map.erase(I++);
           else
             ++I;
Index: llvm/include/llvm/Analysis/ScalarEvolution.h
===================================================================
--- llvm/include/llvm/Analysis/ScalarEvolution.h
+++ llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -1390,6 +1390,9 @@
     /// True iff the backedge is taken either exactly Max or zero times.
     bool MaxOrZero = false;
 
+    /// SCEV expressions used in any of the ExitNotTakenInfo counts.
+    SmallPtrSet<const SCEV *, 4> Operands;
+
     bool isComplete() const { return IsComplete; }
     const SCEV *getConstantMax() const { return ConstantMax; }
 
@@ -1458,7 +1461,7 @@
 
     /// Return true if any backedge taken count expressions refer to the given
     /// subexpression.
-    bool hasOperand(const SCEV *S, ScalarEvolution *SE) const;
+    bool hasOperand(const SCEV *S) const;
   };
 
   /// Cache the backedge-taken count of the loops for this function as they


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