[llvm-commits] [llvm] r63234 - /llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h

[Dan Gohman]

Author: djg
Date: Wed Jan 28 15:13:08 2009
New Revision: 63234

URL: http://llvm.org/viewvc/llvm-project?rev=63234&view=rev
Log:
Add some comments on ISD::NodeType.

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

Modified: llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h?rev=63234&r1=63233&r2=63234&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h (original)
+++ llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h Wed Jan 28 15:13:08 2009
@@ -63,6 +63,13 @@
   /// ISD::NodeType enum - This enum defines all of the operators valid in a
   /// SelectionDAG.
   ///
+  /// These are sometimes called the target-independent operators; targets
+  /// may also define target-dependent operators. For example, on x86, these
+  /// are the enum values in the X86ISD namespace. Targets should aim to use
+  /// target-independent operators to model their instruction sets as much
+  /// as possible, and only use target-dependent operators when they have
+  /// special requirements.
+  ///
   enum NodeType {
     // DELETED_NODE - This is an illegal flag value that is used to catch
     // errors.  This opcode is not a legal opcode for any node.