[llvm-commits] [llvm] r85692 - /llvm/trunk/lib/Transforms/Scalar/GVN.cpp

[Chris Lattner]

Author: lattner
Date: Sat Oct 31 17:11:15 2009
New Revision: 85692

URL: http://llvm.org/viewvc/llvm-project?rev=85692&view=rev
Log:
Make sure PRE doesn't split crit edges from indirectbr.

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=85692&r1=85691&r2=85692&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Sat Oct 31 17:11:15 2009
@@ -1810,7 +1810,7 @@
 
 /// performPRE - Perform a purely local form of PRE that looks for diamond
 /// control flow patterns and attempts to perform simple PRE at the join point.
-bool GVN::performPRE(Function& F) {
+bool GVN::performPRE(Function &F) {
   bool Changed = false;
   SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
   DenseMap<BasicBlock*, Value*> predMap;
@@ -1875,6 +1875,10 @@
       // we would need to insert instructions in more than one pred.
       if (NumWithout != 1 || NumWith == 0)
         continue;
+      
+      // Don't do PRE across indirect branch.
+      if (isa<IndirectBrInst>(PREPred->getTerminator()))
+        continue;
 
       // We can't do PRE safely on a critical edge, so instead we schedule
       // the edge to be split and perform the PRE the next time we iterate