[llvm-commits] [llvm] r121966 - /llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp

[Frits van Bommel]

Author: fvbommel
Date: Thu Dec 16 06:16:00 2010
New Revision: 121966

URL: http://llvm.org/viewvc/llvm-project?rev=121966&view=rev
Log:
Fix a bug in the loop in JumpThreading::ProcessThreadableEdges() where it could falsely produce a MultipleDestSentinel value if the first predecessor ended with an 'indirectbr'. If that happened, it caused an unnecessary FindMostPopularDest() call.
This wasn't a correctness problem, but it broke the fast path for single-predecessor blocks.

Modified:
    llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=121966&r1=121965&r2=121966&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Thu Dec 16 06:16:00 2010
@@ -984,7 +984,7 @@
     }
   }
 
-  // Okay, now we know the most popular destination.  If there is more than
+  // Okay, now we know the most popular destination.  If there is more than one
   // destination, we need to determine one.  This is arbitrary, but we need
   // to make a deterministic decision.  Pick the first one that appears in the
   // successor list.
@@ -1064,7 +1064,7 @@
     }
 
     // If we have exactly one destination, remember it for efficiency below.
-    if (i == 0)
+    if (PredToDestList.empty())
       OnlyDest = DestBB;
     else if (OnlyDest != DestBB)
       OnlyDest = MultipleDestSentinel;