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, 15 insertions, 0 deletions

diff --git a/dwflpp.cxx b/dwflpp.cxx
index dc7af5d8..79561c73 100644
--- a/dwflpp.cxx
+++ b/dwflpp.cxx
@@ -1830,6 +1830,21 @@ dwflpp::translate_final_fetch_or_store (struct obstack *pool,
   typedie = resolve_unqualified_inner_typedie (&typedie_mem, attr_mem, e);
   typetag = dwarf_tag (typedie);
 
+  /* If we're looking for an address, then we can just provide what
+     we computed to this point, without using a fetch/store. */
+  if (e->addressof)
+    {
+      if (lvalue)
+        throw semantic_error ("cannot write to member address", e->tok);
+
+      if (dwarf_hasattr_integrate (die, DW_AT_bit_offset))
+        throw semantic_error ("cannot take address of bit-field", e->tok);
+
+      c_translate_addressof (pool, 1, 0, 0, die, tail, "THIS->__retvalue");
+      ty = pe_long;
+      return;
+    }
+
   /* Then switch behavior depending on the type of fetch/store we
      want, and the type and pointer-ness of the final location. */