[PATCH] D30632: [LoopUnrolling] Fix loop size check for peeling

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.

We should check if loop size allows us to peel at least one iteration before we do so.


https://reviews.llvm.org/D30632

Files:
  lib/Transforms/Utils/LoopUnrollPeel.cpp


Index: lib/Transforms/Utils/LoopUnrollPeel.cpp
===================================================================
--- lib/Transforms/Utils/LoopUnrollPeel.cpp
+++ lib/Transforms/Utils/LoopUnrollPeel.cpp
@@ -71,6 +71,10 @@
   if (!L->empty())
     return;
 
+  // Can we peel at least one iteration?
+  if (LoopSize > UP.Threshold)
+    return;
+
   // Try to find a Phi node that has the same loop invariant as an input from
   // its only back edge. If there is such Phi, peeling 1 iteration from the
   // loop is profitable, because starting from 2nd iteration we will have an


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