[llvm-commits] [llvm] r60393 - /llvm/trunk/lib/Transforms/Scalar/GVN.cpp

[Owen Anderson]

Author: resistor
Date: Mon Dec  1 22:09:22 2008
New Revision: 60393

URL: http://llvm.org/viewvc/llvm-project?rev=60393&view=rev
Log:
Fix an issue that Chris noticed, where local PRE was not properly instantiating
a new value numbering set after splitting a critical edge.  This increases
the number of instances of PRE on 403.gcc from ~60 to ~570.

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

Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=60393&r1=60392&r2=60393&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Mon Dec  1 22:09:22 2008
@@ -1299,6 +1299,7 @@
         
       if (isCriticalEdge(PREPred->getTerminator(), succNum)) {
         toSplit.push_back(std::make_pair(PREPred->getTerminator(), succNum));
+        Changed = true;
         continue;
       }
       
@@ -1361,10 +1362,14 @@
   }
   
   for (SmallVector<std::pair<TerminatorInst*, unsigned>, 4>::iterator
-       I = toSplit.begin(), E = toSplit.end(); I != E; ++I)
+       I = toSplit.begin(), E = toSplit.end(); I != E; ++I) {
     SplitCriticalEdge(I->first, I->second, this);
+    BasicBlock* NewBlock = I->first->getSuccessor(I->second);
+    localAvail[NewBlock] =
+             new ValueNumberScope(localAvail[I->first->getParent()]);
+  }
   
-  return Changed || toSplit.size();
+  return Changed;
 }
 
 // iterateOnFunction - Executes one iteration of GVN