[llvm] r326072 - [SCEV] Factor out getUsedLoops

[Serguei Katkov via llvm-commits]

Author: skatkov
Date: Mon Feb 26 01:26:41 2018
New Revision: 326072

URL: http://llvm.org/viewvc/llvm-project?rev=326072&view=rev
Log:
[SCEV] Factor out getUsedLoops

The patch introduces 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.

Reviewers: sanjoy, mkazantsev, reames
Reviewed By: sanjoy
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D43504

Modified:
    llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=326072&r1=326071&r2=326072&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Mon Feb 26 01:26:41 2018
@@ -1769,6 +1769,11 @@ private:
   const SCEV *getOrCreateMulExpr(SmallVectorImpl<const SCEV *> &Ops,
                                  SCEV::NoWrapFlags Flags);
 
+  /// Find all of the loops transitively used in \p S, and fill \p LoopsUsed.
+  /// A loop is considered "used" by an expression if it contains
+  /// an add rec on said loop.
+  void getUsedLoops(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);

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=326072&r1=326071&r2=326072&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Mon Feb 26 01:26:41 2018
@@ -11341,9 +11341,13 @@ ScalarEvolution::forgetMemoizedResults(c
   RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
 }
 
-void ScalarEvolution::addToLoopUseLists(const SCEV *S) {
+void
+ScalarEvolution::getUsedLoops(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());
@@ -11353,10 +11357,14 @@ void ScalarEvolution::addToLoopUseLists(
     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;
+  getUsedLoops(S, LoopsUsed);
+  for (auto *L : LoopsUsed)
     LoopUsers[L].push_back(S);
 }