[llvm-commits] [llvm] r62713 - /llvm/trunk/include/llvm/CodeGen/SelectionDAG.h

[Dan Gohman]

Author: djg
Date: Wed Jan 21 14:50:09 2009
New Revision: 62713

URL: http://llvm.org/viewvc/llvm-project?rev=62713&view=rev
Log:
Add a comment to SelectionDAG::ReplaceAllUsesWith to describe a subtle
iteraction with SelectionDAG CSE.

Modified:
    llvm/trunk/include/llvm/CodeGen/SelectionDAG.h

Modified: llvm/trunk/include/llvm/CodeGen/SelectionDAG.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/SelectionDAG.h?rev=62713&r1=62712&r2=62713&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CodeGen/SelectionDAG.h (original)
+++ llvm/trunk/include/llvm/CodeGen/SelectionDAG.h Wed Jan 21 14:50:09 2009
@@ -680,6 +680,11 @@
   /// informed about nodes that are deleted and modified due to recursive
   /// changes in the dag.
   ///
+  /// These functions only replace all existing uses. It's possible that as
+  /// these replacements are being performed, CSE may cause the From node
+  /// to be given new uses. These new uses of From are left in place, and
+  /// not automatically transfered to To.
+  ///
   void ReplaceAllUsesWith(SDValue From, SDValue Op,
                           DAGUpdateListener *UpdateListener = 0);
   void ReplaceAllUsesWith(SDNode *From, SDNode *To,