For PR1839: add initial support for __builtin_trap. llvm-gcc part is missed

as well as PPC codegen


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46001 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/SelectionDAGNodes.h

@@ -563,6 +563,9 @@ namespace ISD {
     // chain as output.
     TRAMPOLINE,
 
+    // TRAP - Trapping instruction
+    TRAP,
+
     // BUILTIN_OP_END - This must be the last enum value in this list.
     BUILTIN_OP_END
   };