Fix Regression/Transforms/LoopUnswitch/2006-02-22-UnswitchCrash.ll, which

caused SPASS to fail building last night.

We can't trivially unswitch a loop if the exit block has phi nodes in it,
because we don't know which predecessor to use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26320 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 61a043596d6cab33edf3498eeff93781173763da..b0be443c116e8d2c0864215638afa173c2bf29bf 100644 (file)
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -325,7 +325,9 @@ static bool IsTrivialUnswitchCondition(Loop *L, Value *Cond, Constant **Val = 0,
       }
   }
 
-  if (!LoopExitBB)
+  // If we didn't find a single unique LoopExit block, or if the loop exit block
+  // contains phi nodes, this isn't trivial.
+  if (!LoopExitBB || isa<PHINode>(LoopExitBB->begin()))
     return false;   // Can't handle this.
   
   if (LoopExit) *LoopExit = LoopExitBB;