PR5930: Address-op for $target and @cast members

This allows the '&' operator to get the address of @cast and $target
variable expressions.

* staptree.h (target_symbol): add addressof field
* staptree.cxx (target_symbol::print): print '&' for addressof
  (cast_op::print): ditto
* parse.cxx (parser::parse_value): allow '&' prefix on $target/@cast
* dwflpp.cxx (dwflpp::translate_final_fetch_or_store): allow taking the
  computed address without actually doing a final fetch.
* tapset* (*::visit_target_symbol): throw errors for $vars w/o addresses
* testsuite/systemtap.base/cast.stp: add &@cast test
* testsuite/semok/target_addr.stp: test '&' on different member types
* testsuite/semko/target_addr?.stp: test failure on bitfields/registers

1 files changed, 2 insertions, 1 deletions

diff --git a/staptree.h b/staptree.h
index 7e9506bb..16f0256a 100644
--- a/staptree.h
+++ b/staptree.h
@@ -229,11 +229,12 @@ struct target_symbol: public symbol
       comp_struct_member,
       comp_literal_array_index
     };
+  bool addressof;
   std::string base_name;
   std::vector<std::pair<component_type, std::string> > components;
   std::string probe_context_var;
   semantic_error* saved_conversion_error;
-  target_symbol(): saved_conversion_error (0) {}
+  target_symbol(): addressof(false), saved_conversion_error (0) {}
   void print (std::ostream& o) const;
   void visit (visitor* u);
 };