1 files changed, 21 insertions, 23 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index f7590acc..b3658fb 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -301,11 +301,6 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
   if (ULO.TripMultiple != 1)
     LLVM_DEBUG(dbgs() << "  Trip Multiple = " << ULO.TripMultiple << "\n");
 
-  // Effectively "DCE" unrolled iterations that are beyond the tripcount
-  // and will never be executed.
-  if (ULO.TripCount != 0 && ULO.Count > ULO.TripCount)
-    ULO.Count = ULO.TripCount;
-
   // Don't enter the unroll code if there is nothing to do.
   if (ULO.TripCount == 0 && ULO.Count < 2) {
     LLVM_DEBUG(dbgs() << "Won't unroll; almost nothing to do\n");
@@ -316,17 +311,6 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
   assert(ULO.TripMultiple > 0);
   assert(ULO.TripCount == 0 || ULO.TripCount % ULO.TripMultiple == 0);
 
-  // Are we eliminating the loop control altogether?  Note that we can know
-  // we're eliminating the backedge without knowing exactly which iteration
-  // of the unrolled body exits.
-  const bool CompletelyUnroll = ULO.Count == ULO.TripCount;
-
-  // We assume a run-time trip count if the compiler cannot
-  // figure out the loop trip count and the unroll-runtime
-  // flag is specified.
-  bool RuntimeTripCount =
-      (ULO.TripCount == 0 && ULO.Count > 0 && ULO.AllowRuntime);
-
   // All these values should be taken only after peeling because they might have
   // changed.
   BasicBlock *Preheader = L->getLoopPreheader();
@@ -336,6 +320,27 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
   L->getExitBlocks(ExitBlocks);
   std::vector<BasicBlock *> OriginalLoopBlocks = L->getBlocks();
 
+  const unsigned MaxTripCount = SE->getSmallConstantMaxTripCount(L);
+  const bool MaxOrZero = SE->isBackedgeTakenCountMaxOrZero(L);
+
+  // Effectively "DCE" unrolled iterations that are beyond the max tripcount
+  // and will never be executed.
+  if (MaxTripCount && ULO.Count > MaxTripCount)
+    ULO.Count = MaxTripCount;
+
+  // Are we eliminating the loop control altogether?  Note that we can know
+  // we're eliminating the backedge without knowing exactly which iteration
+  // of the unrolled body exits.
+  const bool CompletelyUnroll = ULO.Count == MaxTripCount;
+
+  const bool PreserveOnlyFirst = CompletelyUnroll && MaxOrZero;
+
+  // We assume a run-time trip count if the compiler cannot
+  // figure out the loop trip count and the unroll-runtime
+  // flag is specified.
+  bool RuntimeTripCount =
+      !CompletelyUnroll && ULO.TripCount == 0 && ULO.AllowRuntime;
+
   // Go through all exits of L and see if there are any phi-nodes there. We just
   // conservatively assume that they're inserted to preserve LCSSA form, which
   // means that complete unrolling might break this form. We need to either fix
@@ -347,11 +352,6 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
       any_of(ExitBlocks,
              [](const BasicBlock *BB) { return isa<PHINode>(BB->begin()); });
 
-  const unsigned MaxTripCount = SE->getSmallConstantMaxTripCount(L);
-  const bool MaxOrZero = SE->isBackedgeTakenCountMaxOrZero(L);
-
-  const bool PreserveOnlyFirst = ULO.Count == MaxTripCount && MaxOrZero;
-
   // The current loop unroll pass can unroll loops that have
   // (1) single latch; and
   // (2a) latch is unconditional; or
@@ -728,8 +728,6 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
         // Complete (but possibly inexact) unrolling
         if (j == 0)
           return true;
-        if (MaxTripCount && j >= MaxTripCount)
-          return false;
         // Warning: ExactTripCount is the trip count of the exiting
         // block which ends in ExitingBI, not neccessarily the loop.
         if (ExactTripCount && j != ExactTripCount)