1 /* Copyright (c) 2008-2013. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
9 #include <elfutils/libdw.h>
12 #include <simgrid_config.h>
14 #include <xbt/sysdep.h>
16 #include "mc_private.h"
18 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dwarf, mc, "DWARF processing");
20 /** \brief The default DW_TAG_lower_bound for a given DW_AT_language.
22 * The default for a given language is defined in the DWARF spec.
24 static uint64_t MC_dwarf_default_lower_bound(int lang);
26 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit);
28 /** \brief Computes the number of elements of a given DW_TAG_array_type
31 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit);
33 /** \brief Checks if a given tag is a (known) type tag.
35 static int MC_dwarf_tag_type(int tag);
36 static void MC_dwarf_handle_die(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t frame);
37 static void MC_dwarf_handle_type_die(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit);
38 static void MC_dwarf_handle_children(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t frame);
39 static void MC_dwarf_handle_variable_die(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t frame);
40 static dw_location_t MC_dwarf_get_expression(Dwarf_Op* expr, size_t len);
41 static Dwarf_Die* MC_dwarf_resolve_die(Dwarf_Die* die, int attribute);
42 static char* MC_dwarf_at_type(Dwarf_Die* die);
44 const char* MC_dwarf_attrname(int attr) {
46 #include "mc_dwarf_attrnames.h"
48 return "DW_AT_unkown";
52 const char* MC_dwarf_tagname(int tag) {
54 #include "mc_dwarf_tagnames.h"
56 return "DW_TAG_invalid";
58 return "DW_TAG_unkown";
62 static inline const char* MC_dwarf_die_tagname(Dwarf_Die* die) {
63 return MC_dwarf_tagname(dwarf_tag(die));
68 static const char* MC_dwarf_attr_string(Dwarf_Die* die, int attribute) {
70 if (!dwarf_attr_integrate(die, attribute, &attr)) {
73 return dwarf_formstring(&attr);
77 /** \brief Get the linkage name (DW_AT_linkage_name or DW_AR_MIPS_linkage_name)
79 static const char* MC_dwarf_at_linkage_name(Dwarf_Die* die) {
80 const char* name = MC_dwarf_attr_string(die, DW_AT_linkage_name);
82 name = MC_dwarf_attr_string(die, DW_AT_MIPS_linkage_name);
86 /** \brief Create a location_list from a given attribute */
87 static dw_location_t MC_dwarf_get_location_list_libdw(Dwarf_Die* die, Dwarf_Attribute* attr) {
90 dw_location_t location = xbt_new0(s_dw_location_t, 1);
91 location->type = e_dw_loclist;
92 xbt_dynar_t loclist = xbt_dynar_new(sizeof(dw_location_entry_t), NULL);
93 location->location.loclist = loclist;
96 Dwarf_Addr base, start, end;
102 offset = dwarf_getlocations(attr, offset, &base, &start, &end, &expr, &len);
106 xbt_die("Error while loading location list");
108 dw_location_entry_t new_entry = xbt_new0(s_dw_location_entry_t, 1);
109 new_entry->lowpc = start;
110 new_entry->highpc = end;
111 new_entry->location = MC_dwarf_get_expression(expr, len);
113 xbt_dynar_push(loclist, &new_entry);
118 static dw_location_t MC_dwarf_get_location(Dwarf_Die* die, Dwarf_Attribute* attr, mc_object_info_t info) {
119 int form = dwarf_whatform(attr);
121 case DW_FORM_exprloc:
122 case DW_FORM_block1: // not in the spec
129 if (dwarf_getlocation(attr, &expr, &len))
130 xbt_die("Could not read location expression");
131 return MC_dwarf_get_expression(expr, len);
133 case DW_FORM_sec_offset:
138 return MC_dwarf_get_location_list_libdw(die, attr);
142 xbt_die("Unexpected form %i list for location in attribute %s of <%p>%s",
144 MC_dwarf_attrname(attr->code),
145 (void*) dwarf_dieoffset(die),
146 MC_dwarf_attr_string(die, DW_AT_name));
151 static dw_location_t MC_dwarf_at_location(Dwarf_Die* die, int attribute, mc_object_info_t info) {
152 if(!dwarf_hasattr_integrate(die, attribute))
153 return xbt_new0(s_dw_location_t, 1);
155 Dwarf_Attribute attr;
156 dwarf_attr_integrate(die, attribute, &attr);
157 return MC_dwarf_get_location(die, &attr, info);
160 // Return a new string for the type (NULL if none)
161 static char* MC_dwarf_at_type(Dwarf_Die* die) {
162 Dwarf_Attribute attr;
163 if (dwarf_hasattr_integrate(die, DW_AT_type)) {
164 dwarf_attr_integrate(die, DW_AT_type, &attr);
165 Dwarf_Die subtype_die;
166 if (dwarf_formref_die(&attr, &subtype_die)==NULL) {
167 xbt_die("Could not find DIE for type");
169 Dwarf_Off subtype_global_offset = dwarf_dieoffset(&subtype_die);
170 return bprintf("%" PRIx64 , subtype_global_offset);
175 static uint64_t MC_dwarf_attr_addr(Dwarf_Die* die, int attribute) {
176 Dwarf_Attribute attr;
177 if(dwarf_attr_integrate(die, attribute, &attr)==NULL)
180 if (dwarf_formaddr(&attr, &value) == 0)
181 return (uint64_t) value;
186 static uint64_t MC_dwarf_attr_uint(Dwarf_Die* die, int attribute, uint64_t default_value) {
187 Dwarf_Attribute attr;
188 if (dwarf_attr_integrate(die, attribute, &attr)==NULL)
189 return default_value;
191 return dwarf_formudata(dwarf_attr_integrate(die, attribute, &attr), &value) == 0 ? (uint64_t) value : default_value;
194 static bool MC_dwarf_attr_flag(Dwarf_Die* die, int attribute, int integrate) {
195 Dwarf_Attribute attr;
196 if ((integrate ? dwarf_attr_integrate(die, attribute, &attr)
197 : dwarf_attr(die, attribute, &attr))==0)
201 if (dwarf_formflag(&attr, &result))
202 xbt_die("Unexpected form for attribute %s",
203 MC_dwarf_attrname(attribute));
207 static uint64_t MC_dwarf_default_lower_bound(int lang) {
212 case DW_LANG_C_plus_plus:
216 case DW_LANG_ObjC_plus_plus:
222 case DW_LANG_Fortran77:
223 case DW_LANG_Fortran90:
224 case DW_LANG_Fortran95:
225 case DW_LANG_Modula2:
226 case DW_LANG_Pascal83:
228 case DW_LANG_Cobol74:
229 case DW_LANG_Cobol85:
232 xbt_die("No default MT_TAG_lower_bound for language %i and none given", lang);
237 static uint64_t MC_dwarf_subrange_element_count(Dwarf_Die* die, Dwarf_Die* unit) {
238 // Use DW_TAG_count if present:
239 if (dwarf_hasattr_integrate(die, DW_AT_count)) {
240 return MC_dwarf_attr_uint(die, DW_AT_count, 0);
243 // Otherwise compute DW_TAG_upper_bound-DW_TAG_lower_bound:
245 if (!dwarf_hasattr_integrate(die, DW_AT_upper_bound)) {
246 // This is not really 0, but the code expects this (we do not know):
249 uint64_t upper_bound = MC_dwarf_attr_uint(die, DW_AT_upper_bound, -1);
251 uint64_t lower_bound = 0;
252 if (dwarf_hasattr_integrate(die, DW_AT_lower_bound)) {
253 lower_bound = MC_dwarf_attr_uint(die, DW_AT_lower_bound, -1);
255 lower_bound = MC_dwarf_default_lower_bound(dwarf_srclang(unit));
257 return upper_bound - lower_bound;
260 static uint64_t MC_dwarf_array_element_count(Dwarf_Die* die, Dwarf_Die* unit) {
261 xbt_assert(dwarf_tag(die)==DW_TAG_array_type,
262 "MC_dwarf_array_element_count called with DIE of type %s", MC_dwarf_die_tagname(die));
267 for (res=dwarf_child(die, &child); res==0; res=dwarf_siblingof(&child,&child)) {
268 int child_tag = dwarf_tag(&child);
269 if (child_tag==DW_TAG_subrange_type ||child_tag==DW_TAG_enumeration_type) {
270 result *= MC_dwarf_subrange_element_count(&child, unit);
278 Dwarf_Off MC_dwarf_resolve_location(unw_cursor_t* c, dw_location_t location, void* frame_pointer_address) {
280 switch (location->type){
282 if (xbt_dynar_length(location->location.compose) > 1){
283 return 0; /* TODO : location list with optimizations enabled */
285 dw_location_t location_entry = xbt_dynar_get_as(location->location.compose, 0, dw_location_t);
286 switch (location_entry->type){
288 unw_get_reg(c, location_entry->location.reg, &res);
290 case e_dw_bregister_op:
291 unw_get_reg(c, location_entry->location.breg_op.reg, &res);
292 return (Dwarf_Off) ((long)res + location_entry->location.breg_op.offset);
294 case e_dw_fbregister_op:
295 if (frame_pointer_address != NULL)
296 return (Dwarf_Off)((char *)frame_pointer_address + location_entry->location.fbreg_op);
300 return 0; /* FIXME : implement other cases (with optimizations enabled) */
310 static void MC_dwarf_fill_member_location(dw_type_t type, dw_type_t member, Dwarf_Die* child) {
311 if (dwarf_hasattr(child, DW_AT_data_bit_offset)) {
312 xbt_die("Can't groke DW_AT_data_bit_offset.");
315 if (!dwarf_hasattr_integrate(child, DW_AT_data_member_location)) {
316 if (type->type != DW_TAG_union_type) {
318 "Missing DW_AT_data_member_location field in DW_TAG_member %s of type <%p>%s",
319 member->name, type->id, type->name);
325 Dwarf_Attribute attr;
326 dwarf_attr_integrate(child, DW_AT_data_member_location, &attr);
327 switch (dwarf_whatform(&attr)) {
329 case DW_FORM_exprloc:
333 if (dwarf_getlocation(&attr, &expr, &len)) {
335 "Could not read location expression DW_AT_data_member_location in DW_TAG_member %s of type <%p>%s",
336 MC_dwarf_attr_string(child, DW_AT_name),
337 type->id, type->name);
339 if (len==1 && expr[0].atom == DW_OP_plus_uconst) {
340 member->offset = expr[0].number;
342 xbt_die("Can't groke this location expression yet. %i %i",
343 len==1 , expr[0].atom == DW_OP_plus_uconst);
355 if (!dwarf_formudata(&attr, &offset))
356 member->offset = offset;
358 xbt_die("Cannot get DW_AT_data_member_%s location <%p>%s",
359 MC_dwarf_attr_string(child, DW_AT_name),
360 type->id, type->name);
366 static void MC_dwarf_add_members(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_type_t type) {
369 xbt_assert(!type->members);
370 type->members = xbt_dynar_new(sizeof(dw_type_t), (void(*)(void*))dw_type_free);
371 for (res=dwarf_child(die, &child); res==0; res=dwarf_siblingof(&child,&child)) {
372 if (dwarf_tag(&child)==DW_TAG_member) {
373 // TODO, we should use another type (because is is not a type but a member)
374 dw_type_t member = xbt_new0(s_dw_type_t, 1);
378 const char* name = MC_dwarf_attr_string(&child, DW_AT_name);
380 member->name = xbt_strdup(name);
384 member->byte_size = MC_dwarf_attr_uint(&child, DW_AT_byte_size, 0);
385 member->element_count = -1;
386 member->dw_type_id = MC_dwarf_at_type(&child);
387 member->members = NULL;
388 member->is_pointer_type = 0;
391 if(dwarf_hasattr(&child, DW_AT_data_bit_offset)) {
392 xbt_die("Can't groke DW_AT_data_bit_offset.");
395 MC_dwarf_fill_member_location(type, member, &child);
397 if (!member->dw_type_id) {
398 xbt_die("Missing type for member %s of <%p>%s", member->name, type->id, type->name);
401 xbt_dynar_push(type->members, &member);
406 static dw_type_t MC_dwarf_die_to_type(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit) {
408 dw_type_t type = xbt_new0(s_dw_type_t, 1);
413 type->element_count = -1;
414 type->dw_type_id = NULL;
415 type->members = NULL;
416 type->is_pointer_type = 0;
419 type->type = dwarf_tag(die);
422 type->id = (void *) dwarf_dieoffset(die);
424 const char* name = MC_dwarf_attr_string(die, DW_AT_name);
426 type->name = xbt_strdup(name);
429 XBT_DEBUG("Processing type <%p>%s", type->id, type->name);
431 type->dw_type_id = MC_dwarf_at_type(die);
433 // Computation of the byte_size;
434 if (dwarf_hasattr_integrate(die, DW_AT_byte_size))
435 type->byte_size = MC_dwarf_attr_uint(die, DW_AT_byte_size, 0);
436 else if (type->type == DW_TAG_array_type || type->type==DW_TAG_structure_type || type->type==DW_TAG_class_type) {
438 if (dwarf_aggregate_size(die, &size)==0) {
439 type->byte_size = size;
443 switch (type->type) {
444 case DW_TAG_array_type:
445 type->element_count = MC_dwarf_array_element_count(die, unit);
446 // TODO, handle DW_byte_stride and (not) DW_bit_stride
449 case DW_TAG_pointer_type:
450 case DW_TAG_reference_type:
451 case DW_TAG_rvalue_reference_type:
452 type->is_pointer_type = 1;
455 case DW_TAG_structure_type:
456 case DW_TAG_union_type:
457 case DW_TAG_class_type:
458 MC_dwarf_add_members(info, die, unit, type);
464 static void MC_dwarf_handle_type_die(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit) {
465 dw_type_t type = MC_dwarf_die_to_type(info, die, unit);
467 char* key = bprintf("%" PRIx64, (uint64_t) type->id);
468 xbt_dict_set(info->types, key, type, NULL);
471 /** \brief Convert libdw location expresion elment into native one (or NULL in some cases) */
472 static dw_location_t MC_dwarf_get_expression_element(Dwarf_Op* op) {
473 dw_location_t element = xbt_new0(s_dw_location_t, 1);
474 uint8_t atom = op->atom;
475 if (atom >= DW_OP_reg0 && atom<= DW_OP_reg31) {
476 element->type = e_dw_register;
477 element->location.reg = atom - DW_OP_reg0;
479 else if (atom >= DW_OP_breg0 && atom<= DW_OP_breg31) {
480 element->type = e_dw_bregister_op;
481 element->location.reg = atom - DW_OP_breg0;
482 element->location.breg_op.offset = op->number;
484 else if (atom >= DW_OP_lit0 && atom<= DW_OP_lit31) {
485 element->type = e_dw_lit;
486 element->location.reg = atom - DW_OP_lit0;
490 element->type = e_dw_fbregister_op;
491 element->location.fbreg_op = op->number;
494 element->type = e_dw_piece;
495 element->location.piece = op->number;
497 case DW_OP_plus_uconst:
498 element->type = e_dw_plus_uconst;
499 element->location.plus_uconst = op->number;
502 element->type = e_dw_arithmetic;
503 element->location.arithmetic = xbt_strdup("abs");
506 element->type = e_dw_arithmetic;
507 element->location.arithmetic = xbt_strdup("and");
510 element->type = e_dw_arithmetic;
511 element->location.arithmetic = xbt_strdup("div");
514 element->type = e_dw_arithmetic;
515 element->location.arithmetic = xbt_strdup("minus");
518 element->type = e_dw_arithmetic;
519 element->location.arithmetic = xbt_strdup("mod");
522 element->type = e_dw_arithmetic;
523 element->location.arithmetic = xbt_strdup("mul");
526 element->type = e_dw_arithmetic;
527 element->location.arithmetic = xbt_strdup("neg");
530 element->type = e_dw_arithmetic;
531 element->location.arithmetic = xbt_strdup("not");
534 element->type = e_dw_arithmetic;
535 element->location.arithmetic = xbt_strdup("or");
538 element->type = e_dw_arithmetic;
539 element->location.arithmetic = xbt_strdup("plus");
542 case DW_OP_stack_value:
547 case DW_OP_deref_size:
548 element->type = e_dw_deref;
549 element->location.deref_size = (unsigned int short) op->number;
552 element->type = e_dw_deref;
553 element->location.deref_size = sizeof(void *);
556 element->type = e_dw_uconstant;
557 element->location.uconstant.bytes = 1;
558 element->location.uconstant.value = (unsigned long int) op->number;
561 element->type = e_dw_sconstant;
562 element->location.uconstant.bytes = 1;
563 element->location.uconstant.value = (unsigned long int) op->number;
567 element->type = e_dw_uconstant;
568 element->location.uconstant.bytes = 1;
569 element->location.uconstant.value = (unsigned long int) op->number;
572 element->type = e_dw_uconstant;
573 element->location.uconstant.bytes = 2;
574 element->location.uconstant.value = (unsigned long int) op->number;
577 element->type = e_dw_uconstant;
578 element->location.uconstant.bytes = 4;
579 element->location.uconstant.value = (unsigned long int) op->number;
582 element->type = e_dw_uconstant;
583 element->location.uconstant.bytes = 8;
584 element->location.uconstant.value = (unsigned long int) op->number;
588 element->type = e_dw_sconstant;
589 element->location.uconstant.bytes = 1;
590 element->location.uconstant.value = (unsigned long int) op->number;
593 element->type = e_dw_sconstant;
594 element->location.uconstant.bytes = 2;
595 element->location.uconstant.value = (unsigned long int) op->number;
598 element->type = e_dw_sconstant;
599 element->location.uconstant.bytes = 4;
600 element->location.uconstant.value = (unsigned long int) op->number;
603 element->type = e_dw_sconstant;
604 element->location.uconstant.bytes = 8;
605 element->location.uconstant.value = (unsigned long int) op->number;
608 element->type = e_dw_unsupported;
614 /** \brief Convert libdw location expresion into native one */
615 static dw_location_t MC_dwarf_get_expression(Dwarf_Op* expr, size_t len) {
616 dw_location_t loc = xbt_new0(s_dw_location_t, 1);
617 loc->type = e_dw_compose;
618 loc->location.compose = xbt_dynar_new(sizeof(dw_location_t), NULL);
621 for (i=0; i!=len; ++i) {
622 dw_location_t element = MC_dwarf_get_expression_element(expr+i);
624 xbt_dynar_push(loc->location.compose, &element);
630 static dw_variable_t MC_die_to_variable(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t frame) {
632 if (MC_dwarf_attr_flag(die, DW_AT_declaration, false))
635 Dwarf_Attribute attr_location;
636 if (dwarf_attr(die, DW_AT_location, &attr_location)==NULL) {
637 // No location: do not add it ?
641 dw_variable_t variable = xbt_new0(s_dw_variable_t, 1);
642 variable->dwarf_offset = dwarf_dieoffset(die);
643 variable->global = frame == NULL; // Can be override base on DW_AT_location
644 variable->name = xbt_strdup(MC_dwarf_attr_string(die, DW_AT_name));
645 variable->type_origin = MC_dwarf_at_type(die);
646 variable->address.address = NULL;
649 switch (form = dwarf_whatform(&attr_location)) {
650 case DW_FORM_exprloc:
651 case DW_FORM_block1: // Not in the spec but found in the wild.
655 if (dwarf_getlocation(&attr_location, &expr, &len)) {
657 "Could not read location expression in DW_AT_location of variable <%p>%s",
658 (void*) variable->dwarf_offset, variable->name);
661 if (len==1 && expr[0].atom == DW_OP_addr) {
662 variable->global = 1;
663 Dwarf_Off offset = expr[0].number;
664 // TODO, Why is this different base on the object?
665 Dwarf_Off base = strcmp(info->file_name, xbt_binary_name) !=0 ? (Dwarf_Off) info->start_text : 0;
666 variable->address.address = (void*) (base + offset);
668 variable->address.location = MC_dwarf_get_expression(expr, len);
673 case DW_FORM_sec_offset: // type loclistptr
675 xbt_die("Do not handle loclist locations yet");
678 xbt_die("Unexpected form %i list for location in <%p>%s",
679 form, (void*) variable->dwarf_offset, variable->name);
685 static void MC_dwarf_handle_variable_die(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t frame) {
686 dw_variable_t variable = MC_die_to_variable(info, die, unit, frame);
689 MC_dwarf_register_variable(info, frame, variable);
692 static void MC_dwarf_handle_subprogram_die(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t parent_frame) {
693 dw_frame_t frame = xbt_new0(s_dw_frame_t, 1);
695 frame->start = dwarf_dieoffset(die);
697 const char* name = MC_dwarf_at_linkage_name(die);
699 name = MC_dwarf_attr_string(die, DW_AT_name);
700 frame->name = xbt_strdup(name);
702 // Variables are filled in the (recursive) call of MC_dwarf_handle_children:
703 frame->variables = xbt_dynar_new(sizeof(dw_variable_t), dw_variable_free_voidp);
704 frame->high_pc = (void*) MC_dwarf_attr_addr(die, DW_AT_high_pc);
705 frame->low_pc = (void*) MC_dwarf_attr_addr(die, DW_AT_low_pc);
706 frame->frame_base = MC_dwarf_at_location(die, DW_AT_frame_base, info);
707 frame->end = -1; // This one is now useless:
710 MC_dwarf_handle_children(info, die, unit, frame);
713 xbt_dict_set(info->local_variables, frame->name, frame, NULL);
716 static void MC_dwarf_handle_children(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t frame) {
719 for (res=dwarf_child(die, &child); res==0; res=dwarf_siblingof(&child,&child)) {
720 MC_dwarf_handle_die(info, &child, unit, frame);
724 static void MC_dwarf_handle_die(mc_object_info_t info, Dwarf_Die* die, Dwarf_Die* unit, dw_frame_t frame) {
725 int tag = dwarf_tag(die);
727 case DW_TAG_array_type:
728 case DW_TAG_class_type:
729 case DW_TAG_enumeration_type:
731 case DW_TAG_pointer_type:
732 case DW_TAG_string_type:
733 case DW_TAG_structure_type:
734 case DW_TAG_subroutine_type:
735 case DW_TAG_union_type:
736 case DW_TAG_ptr_to_member_type:
737 case DW_TAG_set_type:
738 case DW_TAG_subrange_type:
739 case DW_TAG_base_type:
740 case DW_TAG_const_type:
741 case DW_TAG_file_type:
742 case DW_TAG_packed_type:
743 case DW_TAG_volatile_type:
744 case DW_TAG_restrict_type:
745 case DW_TAG_interface_type:
746 case DW_TAG_unspecified_type:
747 case DW_TAG_mutable_type:
748 case DW_TAG_shared_type:
749 MC_dwarf_handle_type_die(info, die, unit);
751 case DW_TAG_inlined_subroutine:
752 case DW_TAG_subprogram:
753 MC_dwarf_handle_subprogram_die(info, die, unit, frame);
755 // case DW_TAG_formal_parameter:
756 case DW_TAG_variable:
757 MC_dwarf_handle_variable_die(info, die, unit, frame);
761 // Recursive processing of children DIE:
762 MC_dwarf_handle_children(info, die, unit, frame);
765 void MC_dwarf_get_variables(mc_object_info_t info) {
766 int fd = open(info->file_name, O_RDONLY);
768 xbt_die("Could not open file %s", info->file_name);
770 Dwarf *dwarf = dwarf_begin(fd, DWARF_C_READ);
772 xbt_die("Your program must be compiled with -g");
775 Dwarf_Off offset = 0;
776 Dwarf_Off next_offset = 0;
778 while (dwarf_nextcu (dwarf, offset, &next_offset, &length, NULL, NULL, NULL) == 0) {
780 if(dwarf_offdie(dwarf, offset+length, &die)!=NULL) {
781 MC_dwarf_handle_die(info, &die, &die, NULL);
783 offset = next_offset;