[llvm-commits] [llvm] r70052 - /llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Dan Gohman]

Author: djg
Date: Sat Apr 25 12:09:45 2009
New Revision: 70052

URL: http://llvm.org/viewvc/llvm-project?rev=70052&view=rev
Log:
Add a top-level comment about DAGCombiner's role in the compiler.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=70052&r1=70051&r2=70052&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sat Apr 25 12:09:45 2009
@@ -10,6 +10,10 @@
 // This pass combines dag nodes to form fewer, simpler DAG nodes.  It can be run
 // both before and after the DAG is legalized.
 //
+// This pass is not a substitute for the LLVM IR instcombine pass. This pass is
+// primarily intended to handle simplification opportunities that are implicit
+// in the LLVM IR and exposed by the various codegen lowering phases.
+//
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "dagcombine"