[llvm-commits] [llvm] r82319 - /llvm/trunk/lib/Analysis/SparsePropagation.cpp

[Nick Lewycky]

Author: nicholas
Date: Sat Sep 19 14:00:06 2009
New Revision: 82319

URL: http://llvm.org/viewvc/llvm-project?rev=82319&view=rev
Log:
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Modified:
    llvm/trunk/lib/Analysis/SparsePropagation.cpp

Modified: llvm/trunk/lib/Analysis/SparsePropagation.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/SparsePropagation.cpp?rev=82319&r1=82318&r2=82319&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/SparsePropagation.cpp (original)
+++ llvm/trunk/lib/Analysis/SparsePropagation.cpp Sat Sep 19 14:00:06 2009
@@ -223,6 +223,9 @@
 }
 
 void SparseSolver::visitPHINode(PHINode &PN) {
+  // The lattice function may store more information on a PHINode than could be
+  // computed from its incoming values.  For example, SSI form stores its sigma
+  // functions as PHINodes with a single incoming value.
   if (LatticeFunc->IsSpecialCasedPHI(&PN)) {
     LatticeVal IV = LatticeFunc->ComputeInstructionState(PN, *this);
     if (IV != LatticeFunc->getUntrackedVal())