Enable dwarf expansion of @casts

This will iterate over the module and its CUs looking for the type
definition, and then work with loc2c to dereference the pointer.

* loc2c.c (c_translate_argument): Create a dummy location to start
the address computation from a function parameter.
* translate.cxx (base_query, dwarf_query): Move some members from
base_query to dwarf_query, so the former can be more generic.  Also
add a constructor using a module string instead of probe parameters.
(dwflpp::query_modules, dwflpp::iterate_over_modules): Use a generic
base_query instead of a dwarf_query.
(dwarf_cast_query): New query to scan the modules and CUs for a
matching type definition, and then produce a code fragment to deref
each component.
(dwarf_cast_expanding_visitor): Tries to replace @casts with a function
call to the result of a dwarf_cast_query.
(dwflpp::declaration_resolve): Search by name instead of by die.
(dwflpp::translate_components): Use the incoming vardie as the first
type die, so we don't assume that attr_mem has a DW_AT_type already.
(dwflpp::literal_stmt_for_pointer): Construct a C fragment that starts
with a pointer argument (THIS->pointer) and dereferences each member
component from there.
(*_derived_probe::register_patterns): Take a session parameter instead
of a match_node, so we can manipulate session-wide data.
(dwarf_derived_probe::register_patterns): Add a session code filter to
expand @casts with a dwarf_cast_expanding_visitor.

1 files changed, 15 insertions, 0 deletions

diff --git a/loc2c.h b/loc2c.h
index 67f4a38a..0ad5ae99 100644
--- a/loc2c.h
+++ b/loc2c.h
@@ -85,6 +85,21 @@ c_translate_pointer_store (struct obstack *pool, int indent,
                            Dwarf_Die *typedie, struct location **input,
                            const char *rvalue);
 
+/* Translate a C fragment for a direct argument VALUE.  On errors, call FAIL,
+   which should not return.  Any later errors will use FAIL and FAIL_ARG from
+   this translate call.  On success, return the fragment created. */
+struct location *c_translate_argument (struct obstack *,
+				       void (*fail) (void *arg,
+						     const char *fmt, ...)
+				       __attribute__ ((noreturn,
+						       format (printf, 2, 3))),
+				       void *fail_arg,
+				       void (*emit_address) (void *fail_arg,
+							     struct obstack *,
+							     Dwarf_Addr),
+				       int indent, const char *value);
+
+
 
 /* Emit the C fragment built up at LOC (i.e., the return value from the
    first c_translate_location call made).  INDENT should match that