Create a dwarf_attr_die idiom

We commonly do a dwarf_attr_integrate followed by dwarf_formref_die,
with no care for the Dwarf_Attribute, so I captured that idiom in an
inline function.

* dwarf_wrappers.h (dwarf_attr_die): New.
* dwarf_wrappers.cxx (dwarf_type_name): Call dwarf_attr_die.
* dwflpp.cxx (dwflpp::print_members): Ditto.
  (dwflpp::find_struct_member): Ditto.
* tapsets.cxx (dwarf_derived_probe::saveargs): Ditto.
  (uprobe_derived_probe::saveargs): Ditto.
  (resolve_tracepoint_arg_type): Ditto.
  (tracepoint_derived_probe::build_args): Ditto.

4 files changed, 21 insertions, 31 deletions

diff --git a/dwarf_wrappers.cxx b/dwarf_wrappers.cxx
index fe8ead07..7b64aac5 100644
--- a/dwarf_wrappers.cxx
+++ b/dwarf_wrappers.cxx
@@ -125,10 +125,8 @@ dwarf_type_name(Dwarf_Die *type_die, ostringstream& o)
 
   // recurse into the referent type
   // if it can't be named, just call it "void"
-  Dwarf_Attribute subtype_attr;
   Dwarf_Die subtype_die;
-  if (!dwarf_attr_integrate(type_die, DW_AT_type, &subtype_attr)
-      || !dwarf_formref_die(&subtype_attr, &subtype_die)
+  if (!dwarf_attr_die(type_die, DW_AT_type, &subtype_die)
       || !dwarf_type_name(&subtype_die, o))
     o.str("void"), o.seekp(4);
 
diff --git a/dwarf_wrappers.h b/dwarf_wrappers.h
index bc1cde2b..766abb6d 100644
--- a/dwarf_wrappers.h
+++ b/dwarf_wrappers.h
@@ -103,6 +103,16 @@ public:
 };
 
 
+// Look up the DIE for a reference-form attribute name
+inline Dwarf_Die *
+dwarf_attr_die (Dwarf_Die *die, unsigned int attr, Dwarf_Die *result)
+{
+  Dwarf_Attribute attr_mem;
+  return dwarf_formref_die (dwarf_attr_integrate (die, attr, &attr_mem),
+                            result);
+}
+
+
 #if !_ELFUTILS_PREREQ(0, 143)
 // Elfutils prior to 0.143 didn't use attr_integrate when looking up the
 // decl_file or decl_line, so the attributes would sometimes be missed.  For
diff --git a/dwflpp.cxx b/dwflpp.cxx
index dcf04678..dce19f21 100644
--- a/dwflpp.cxx
+++ b/dwflpp.cxx
@@ -1588,10 +1588,7 @@ dwflpp::print_members(Dwarf_Die *vardie, ostream &o)
       else
         {
           Dwarf_Die temp_die;
-          Dwarf_Attribute temp_attr;
-
-          if (!dwarf_attr_integrate (die, DW_AT_type, &temp_attr) ||
-              !dwarf_formref_die (&temp_attr, &temp_die))
+          if (!dwarf_attr_die (die, DW_AT_type, &temp_die))
             {
               string source = dwarf_decl_file(die) ?: "<unknown source>";
               int line = -1;
@@ -1642,12 +1639,8 @@ dwflpp::find_struct_member(const target_symbol::component& c,
         {
           // need to recurse for anonymous structs/unions
           Dwarf_Die subdie;
-
-          if (!dwarf_attr_integrate (&die, DW_AT_type, &attr) ||
-              !dwarf_formref_die (&attr, &subdie))
-            continue;
-
-          if (find_struct_member(c, &subdie, memberdie, locs))
+          if (dwarf_attr_die (&die, DW_AT_type, &subdie) &&
+              find_struct_member(c, &subdie, memberdie, locs))
             goto success;
         }
       else if (name == c.member)
diff --git a/tapsets.cxx b/tapsets.cxx
index 0e46962d..04d03503 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -2780,12 +2780,10 @@ dwarf_derived_probe::saveargs(Dwarf_Die* scope_die)
 
   stringstream argstream;
   string type_name;
-  Dwarf_Attribute type_attr;
   Dwarf_Die type_die;
 
   if (has_return &&
-      dwarf_attr_integrate (scope_die, DW_AT_type, &type_attr) &&
-      dwarf_formref_die (&type_attr, &type_die) &&
+      dwarf_attr_die (scope_die, DW_AT_type, &type_die) &&
       dwarf_type_name(&type_die, type_name))
     argstream << " $return:" << type_name;
 
@@ -2808,8 +2806,7 @@ dwarf_derived_probe::saveargs(Dwarf_Die* scope_die)
           continue;
 
         type_name.clear();
-        if (!dwarf_attr_integrate (&arg, DW_AT_type, &type_attr) ||
-            !dwarf_formref_die (&type_attr, &type_die) ||
+        if (!dwarf_attr_die (&arg, DW_AT_type, &type_die) ||
             !dwarf_type_name(&type_die, type_name))
           continue;
 
@@ -4286,12 +4283,10 @@ uprobe_derived_probe::saveargs(Dwarf_Die* scope_die)
 
   stringstream argstream;
   string type_name;
-  Dwarf_Attribute type_attr;
   Dwarf_Die type_die;
 
   if (return_p &&
-      dwarf_attr_integrate (scope_die, DW_AT_type, &type_attr) &&
-      dwarf_formref_die (&type_attr, &type_die) &&
+      dwarf_attr_die (scope_die, DW_AT_type, &type_die) &&
       dwarf_type_name(&type_die, type_name))
     argstream << " $return:" << type_name;
 
@@ -4314,8 +4309,7 @@ uprobe_derived_probe::saveargs(Dwarf_Die* scope_die)
           continue;
 
         type_name.clear();
-        if (!dwarf_attr_integrate (&arg, DW_AT_type, &type_attr) ||
-            !dwarf_formref_die (&type_attr, &type_die) ||
+        if (!dwarf_attr_die (&arg, DW_AT_type, &type_die) ||
             !dwarf_type_name(&type_die, type_name))
           continue;
 
@@ -5583,15 +5577,13 @@ tracepoint_derived_probe::tracepoint_derived_probe (systemtap_session& s,
 static bool
 resolve_tracepoint_arg_type(tracepoint_arg& arg)
 {
-  Dwarf_Attribute type_attr;
   switch (dwarf_tag(&arg.type_die))
     {
     case DW_TAG_typedef:
     case DW_TAG_const_type:
     case DW_TAG_volatile_type:
       // iterate on the referent type
-      return (dwarf_attr_integrate(&arg.type_die, DW_AT_type, &type_attr)
-              && dwarf_formref_die(&type_attr, &arg.type_die)
+      return (dwarf_attr_die(&arg.type_die, DW_AT_type, &arg.type_die)
               && resolve_tracepoint_arg_type(arg));
     case DW_TAG_base_type:
       // base types will simply be treated as script longs
@@ -5600,8 +5592,7 @@ resolve_tracepoint_arg_type(tracepoint_arg& arg)
     case DW_TAG_pointer_type:
       // pointers can be treated as script longs,
       // and if we know their type, they can also be dereferenced
-      if (dwarf_attr_integrate(&arg.type_die, DW_AT_type, &type_attr)
-          && dwarf_formref_die(&type_attr, &arg.type_die))
+      if (dwarf_attr_die(&arg.type_die, DW_AT_type, &arg.type_die))
         arg.isptr = true;
       arg.typecast = "(intptr_t)";
       return true;
@@ -5632,9 +5623,7 @@ tracepoint_derived_probe::build_args(dwflpp& dw, Dwarf_Die& func_die)
           tparg.name = dwarf_diename(&arg);
 
           // read the type of this parameter
-          Dwarf_Attribute type_attr;
-          if (!dwarf_attr_integrate (&arg, DW_AT_type, &type_attr)
-              || !dwarf_formref_die (&type_attr, &tparg.type_die)
+          if (!dwarf_attr_die (&arg, DW_AT_type, &tparg.type_die)
               || !dwarf_type_name(&tparg.type_die, tparg.c_type))
             throw semantic_error ("cannot get type of tracepoint '"
                                   + tracepoint_name + "' parameter '"