Cut off crazy computation. This helps PR1622 slightly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41522 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 416e1f012a..218da9773d 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -8283,6 +8283,10 @@ static bool DeadPHICycle(PHINode *PN,
   // Remember this node, and if we find the cycle, return.
   if (!PotentiallyDeadPHIs.insert(PN))
     return true;
+  
+  // Don't scan crazily complex things.
+  if (PotentiallyDeadPHIs.size() == 16)
+    return false;
 
   if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
     return DeadPHICycle(PU, PotentiallyDeadPHIs);