[NFC] Move functon from IndVarSimplify to SCEV

This function can be reused in other places.

Differential Revision: https://reviews.llvm.org/D87274
Reviewed By: fhahn, lebedev.ri

diff --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 81c5fc9..ea84144 100644 (file)
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -768,6 +768,11 @@ public:
     return getBackedgeTakenCount(L, ConstantMaximum);
   } 
 
+  /// Return a symbolic upper bound for the backedge taken count of the loop.
+  /// This is more general than getConstantMaxBackedgeTakenCount as it returns
+  /// an arbitrary expression as opposed to only constants.
+  const SCEV* computeMaxBackedgeTakenCount(const Loop *L);
+
   /// Return true if the backedge taken count is either the value returned by
   /// getConstantMaxBackedgeTakenCount or zero.
   bool isBackedgeTakenCountMaxOrZero(const Loop *L);

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 40d89ff..11d92bc 100644 (file)
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -12506,3 +12506,28 @@ bool ScalarEvolution::matchURem(const SCEV *Expr, const SCEV *&LHS,
            MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(0)));
   return false;
 }
+
+const SCEV* ScalarEvolution::computeMaxBackedgeTakenCount(const Loop *L) {
+  SmallVector<BasicBlock*, 16> ExitingBlocks;
+  L->getExitingBlocks(ExitingBlocks);
+
+  // Form an expression for the maximum exit count possible for this loop. We
+  // merge the max and exact information to approximate a version of
+  // getConstantMaxBackedgeTakenCount which isn't restricted to just constants.
+  SmallVector<const SCEV*, 4> ExitCounts;
+  for (BasicBlock *ExitingBB : ExitingBlocks) {
+    const SCEV *ExitCount = getExitCount(L, ExitingBB);
+    if (isa<SCEVCouldNotCompute>(ExitCount))
+      ExitCount = getExitCount(L, ExitingBB,
+                                  ScalarEvolution::ConstantMaximum);
+    if (!isa<SCEVCouldNotCompute>(ExitCount)) {
+      assert(DT.dominates(ExitingBB, L->getLoopLatch()) &&
+             "We should only have known counts for exiting blocks that "
+             "dominate latch!");
+      ExitCounts.push_back(ExitCount);
+    }
+  }
+  if (ExitCounts.empty())
+    return getCouldNotCompute();
+  return getUMinFromMismatchedTypes(ExitCounts);
+}

diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
index 51d12fa..20b8562 100644 (file)
--- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -2329,36 +2329,6 @@ bool IndVarSimplify::sinkUnusedInvariants(Loop *L) {
   return MadeAnyChanges;
 }
 
-/// Return a symbolic upper bound for the backedge taken count of the loop.
-/// This is more general than getConstantMaxBackedgeTakenCount as it returns
-/// an arbitrary expression as opposed to only constants.
-/// TODO: Move into the ScalarEvolution class.
-static const SCEV* getMaxBackedgeTakenCount(ScalarEvolution &SE,
-                                            DominatorTree &DT, Loop *L) {
-  SmallVector<BasicBlock*, 16> ExitingBlocks;
-  L->getExitingBlocks(ExitingBlocks);
-
-  // Form an expression for the maximum exit count possible for this loop. We
-  // merge the max and exact information to approximate a version of
-  // getConstantMaxBackedgeTakenCount which isn't restricted to just constants.
-  SmallVector<const SCEV*, 4> ExitCounts;
-  for (BasicBlock *ExitingBB : ExitingBlocks) {
-    const SCEV *ExitCount = SE.getExitCount(L, ExitingBB);
-    if (isa<SCEVCouldNotCompute>(ExitCount))
-      ExitCount = SE.getExitCount(L, ExitingBB,
-                                  ScalarEvolution::ConstantMaximum);
-    if (!isa<SCEVCouldNotCompute>(ExitCount)) {
-      assert(DT.dominates(ExitingBB, L->getLoopLatch()) &&
-             "We should only have known counts for exiting blocks that "
-             "dominate latch!");
-      ExitCounts.push_back(ExitCount);
-    }
-  }
-  if (ExitCounts.empty())
-    return SE.getCouldNotCompute();
-  return SE.getUMinFromMismatchedTypes(ExitCounts);
-}
-
 bool IndVarSimplify::optimizeLoopExits(Loop *L, SCEVExpander &Rewriter) {
   SmallVector<BasicBlock*, 16> ExitingBlocks;
   L->getExitingBlocks(ExitingBlocks);
@@ -2391,7 +2361,7 @@ bool IndVarSimplify::optimizeLoopExits(Loop *L, SCEVExpander &Rewriter) {
     return false;
 
   // Get a symbolic upper bound on the loop backedge taken count.
-  const SCEV *MaxExitCount = getMaxBackedgeTakenCount(*SE, *DT, L);
+  const SCEV *MaxExitCount = SE->computeMaxBackedgeTakenCount(L);
   if (isa<SCEVCouldNotCompute>(MaxExitCount))
     return false;