[PATCH] D43504: [SCEV] Factor out getLoopUseLists

[Serguei Katkov via Phabricator via llvm-commits]

skatkov created this revision.
skatkov added reviewers: sanjoy, mkazantsev, reames.

The patch introduce the new function in ScalarEvolution to get
all loops used in specified SCEV.

This is a preparation for re-writing isKnownPredicate utility as
described in https://reviews.llvm.org/D42417.


https://reviews.llvm.org/D43504

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


Index: lib/Analysis/ScalarEvolution.cpp
===================================================================
--- lib/Analysis/ScalarEvolution.cpp
+++ lib/Analysis/ScalarEvolution.cpp
@@ -11339,9 +11339,13 @@
   RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
 }
 
-void ScalarEvolution::addToLoopUseLists(const SCEV *S) {
+void
+ScalarEvolution::getLoopUseLists(const SCEV *S,
+                                 SmallPtrSetImpl<const Loop *> &LoopsUsed) {
   struct FindUsedLoops {
-    SmallPtrSet<const Loop *, 8> LoopsUsed;
+    FindUsedLoops(SmallPtrSetImpl<const Loop *> &LoopsUsed)
+        : LoopsUsed(LoopsUsed) {}
+    SmallPtrSetImpl<const Loop *> &LoopsUsed;
     bool follow(const SCEV *S) {
       if (auto *AR = dyn_cast<SCEVAddRecExpr>(S))
         LoopsUsed.insert(AR->getLoop());
@@ -11351,10 +11355,14 @@
     bool isDone() const { return false; }
   };
 
-  FindUsedLoops F;
+  FindUsedLoops F(LoopsUsed);
   SCEVTraversal<FindUsedLoops>(F).visitAll(S);
+}
 
-  for (auto *L : F.LoopsUsed)
+void ScalarEvolution::addToLoopUseLists(const SCEV *S) {
+  SmallPtrSet<const Loop *, 8> LoopsUsed;
+  getLoopUseLists(S, LoopsUsed);
+  for (auto *L : LoopsUsed)
     LoopUsers[L].push_back(S);
 }
 
Index: include/llvm/Analysis/ScalarEvolution.h
===================================================================
--- include/llvm/Analysis/ScalarEvolution.h
+++ include/llvm/Analysis/ScalarEvolution.h
@@ -1764,6 +1764,9 @@
   const SCEV *getOrCreateMulExpr(SmallVectorImpl<const SCEV *> &Ops,
                                  SCEV::NoWrapFlags Flags);
 
+  /// Find all of the loops transitively used in \p S, and fill \p LoopsUsed.
+  void getLoopUseLists(const SCEV *S, SmallPtrSetImpl<const Loop *> &LoopsUsed);
+
   /// Find all of the loops transitively used in \p S, and update \c LoopUsers
   /// accordingly.
   void addToLoopUseLists(const SCEV *S);


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