[llvm] [Analysis] Add getPredicatedExitCount to ScalarEvolution (PR #105649)

[Florian Hahn via llvm-commits]

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@@ -8575,30 +8592,53 @@ const SCEV *ScalarEvolution::BackedgeTakenInfo::getExact(
 }
 
 /// Get the exact not taken count for this loop exit.
-const SCEV *
-ScalarEvolution::BackedgeTakenInfo::getExact(const BasicBlock *ExitingBlock,
-                                             ScalarEvolution *SE) const {
+const SCEV *ScalarEvolution::BackedgeTakenInfo::getExact(
+    const BasicBlock *ExitingBlock, ScalarEvolution *SE,
+    SmallVectorImpl<const SCEVPredicate *> *Predicates) const {
   for (const auto &ENT : ExitNotTaken)
-    if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
-      return ENT.ExactNotTaken;
+    if (ENT.ExitingBlock == ExitingBlock) {
+      if (ENT.hasAlwaysTruePredicate())
+        return ENT.ExactNotTaken;
+      else if (Predicates) {
+        for (const auto *P : ENT.Predicates)
+          Predicates->push_back(P);
+        return ENT.ExactNotTaken;
+      }
+    }
 
   return SE->getCouldNotCompute();
 }
 
 const SCEV *ScalarEvolution::BackedgeTakenInfo::getConstantMax(
-    const BasicBlock *ExitingBlock, ScalarEvolution *SE) const {
+    const BasicBlock *ExitingBlock, ScalarEvolution *SE,
+    SmallVectorImpl<const SCEVPredicate *> *Predicates) const {
   for (const auto &ENT : ExitNotTaken)
-    if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
-      return ENT.ConstantMaxNotTaken;
+    if (ENT.ExitingBlock == ExitingBlock) {
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fhahn wrote:

It would be great to avoid duplicating this logic multiple times by passing a lambda that returns the desired count (or pass  `ExitCountKind` and select based on that).

Not sure if that would overall be much simpler/desirable  though

https://github.com/llvm/llvm-project/pull/105649