Avoid a confusing assert for silly options: -unroll-runtime -unroll-count=1.

No need for an explicit test case for an unsupported combination of options.

llvm-svn: 146721

diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index b96f14b..512b689 100644 (file)
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -176,6 +176,11 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
   if (TripCount != 0 && Count > TripCount)
     Count = TripCount;
 
+  // Don't enter the unroll code if there is nothing to do. This way we don't
+  // need to support "partial unrolling by 1".
+  if (TripCount == 0 && Count < 2)
+    return false;
+
   assert(Count > 0);
   assert(TripMultiple > 0);
   assert(TripCount == 0 || TripCount % TripMultiple == 0);