Revert "[LoopUnroll] Use the upper bound of the loop trip count to fullly unroll a loop"

This reverts commit r284044.

llvm-svn: 284051

1 files changed, 10 insertions, 20 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 8389e3c34c3..70e0c297a8d 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -5292,20 +5292,6 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) {
 //                   Iteration Count Computation Code
 //
 
-static unsigned getConstantTripCount(const SCEVConstant *ExitCount) {
-  if (!ExitCount)
-    return 0;
-
-  ConstantInt *ExitConst = ExitCount->getValue();
-
-  // Guard against huge trip counts.
-  if (ExitConst->getValue().getActiveBits() > 32)
-    return 0;
-
-  // In case of integer overflow, this returns 0, which is correct.
-  return ((unsigned)ExitConst->getZExtValue()) + 1;
-}
-
 unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L) {
   if (BasicBlock *ExitingBB = L->getExitingBlock())
     return getSmallConstantTripCount(L, ExitingBB);
@@ -5321,13 +5307,17 @@ unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L,
          "Exiting block must actually branch out of the loop!");
   const SCEVConstant *ExitCount =
       dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
-  return getConstantTripCount(ExitCount);
-}
+  if (!ExitCount)
+    return 0;
+
+  ConstantInt *ExitConst = ExitCount->getValue();
 
-unsigned ScalarEvolution::getSmallConstantMaxTripCount(Loop *L) {
-  const auto *MaxExitCount =
-      dyn_cast<SCEVConstant>(getMaxBackedgeTakenCount(L));
-  return getConstantTripCount(MaxExitCount);
+  // Guard against huge trip counts.
+  if (ExitConst->getValue().getActiveBits() > 32)
+    return 0;
+
+  // In case of integer overflow, this returns 0, which is correct.
+  return ((unsigned)ExitConst->getZExtValue()) + 1;
 }
 
 unsigned ScalarEvolution::getSmallConstantTripMultiple(Loop *L) {