Change the 'isStore' inferrer to look for 'SDNPMayStore' 
instead of "ISD::STORE".  This allows us to mark target-specific dag
nodes as storing (such as ppc byteswap stores).  This allows us to remove
more explicit isStore flags from the .td files.

Finally, add a warning for when a .td file contains an explicit 
isStore and tblgen is able to infer it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45654 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/CodeGenTarget.h b/utils/TableGen/CodeGenTarget.h
index f024c1d..02afe95 100644
--- a/utils/TableGen/CodeGenTarget.h
+++ b/utils/TableGen/CodeGenTarget.h
@@ -30,8 +30,15 @@
 class CodeGenTarget;
 
 // SelectionDAG node properties.
-enum SDNP { SDNPCommutative, SDNPAssociative, SDNPHasChain,
-            SDNPOutFlag, SDNPInFlag, SDNPOptInFlag  };
+enum SDNP {
+  SDNPCommutative, 
+  SDNPAssociative, 
+  SDNPHasChain,
+  SDNPOutFlag,
+  SDNPInFlag,
+  SDNPOptInFlag,
+  SDNPMayStore
+};
 
 /// getValueType - Return the MVT::ValueType that the specified TableGen record
 /// corresponds to.