[llvm-commits] [llvm] r48283 - /llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h

[Evan Cheng]

Author: evancheng
Date: Wed Mar 12 02:52:15 2008
New Revision: 48283

URL: http://llvm.org/viewvc/llvm-project?rev=48283&view=rev
Log:
Document an implementation detail about EXTRACT_SUBREG and INSERT_SUBREG sub-register operand.

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=48283&r1=48282&r2=48283&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h (original)
+++ llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h Wed Mar 12 02:52:15 2008
@@ -320,6 +320,9 @@
     
     // EXTRACT_SUBREG - This node is used to extract a sub-register value. 
     // This node takes a superreg and a constant sub-register index as operands.
+    // Note sub-register indices must be increasing. That is, if the
+    // sub-register index of a 8-bit sub-register is N, then the index for a
+    // 16-bit sub-register must be at least N+1.
     EXTRACT_SUBREG,
     
     // INSERT_SUBREG - This node is used to insert a sub-register value.