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binutils/dwarf.c: abbrev caching
I'm inclined to think that abbrev caching is counter-productive. The time taken to search the list of abbrevs converted to internal form is non-zero, and it's easy to decode the raw abbrevs. It's especially silly to cache empty lists of decoded abbrevs (happens with zero padding in .debug_abbrev), or abbrevs as they are displayed when there is no further use of those abbrevs. This patch stops caching in those cases. * dwarf.c (record_abbrev_list_for_cu): Add free_list param. Put abbrevs on abbrev_lists here. (new_abbrev_list): Delete function. (process_abbrev_set): Return newly allocated list. Move abbrev base, offset and size checking to.. (find_and_process_abbrev_set): ..here, new function. Handle lookup of cached abbrevs here, and calculate start and end for process_abbrev_set. Return free_list if newly alloc'd. (process_debug_info): Consolidate cached list lookup, new list alloc and processing into find_and_process_abbrev_set call. Free list when not cached. (display_debug_abbrev): Similarly.
This commit is contained in:
Alan Modra
parent
175b91507b
commit
f07c08e115
208
binutils/dwarf.c
208
binutils/dwarf.c
@ -882,8 +882,15 @@ static unsigned long next_free_abbrev_map_entry = 0;
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#define ABBREV_MAP_ENTRIES_INCREMENT 8
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static void
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record_abbrev_list_for_cu (dwarf_vma start, dwarf_vma end, abbrev_list * list)
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record_abbrev_list_for_cu (dwarf_vma start, dwarf_vma end,
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abbrev_list *list, abbrev_list *free_list)
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{
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if (free_list != NULL)
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{
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list->next = abbrev_lists;
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abbrev_lists = list;
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}
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if (cu_abbrev_map == NULL)
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{
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num_abbrev_map_entries = INITIAL_NUM_ABBREV_MAP_ENTRIES;
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@ -938,20 +945,6 @@ free_all_abbrevs (void)
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next_free_abbrev_map_entry = 0;
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}
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static abbrev_list *
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new_abbrev_list (dwarf_vma abbrev_base, dwarf_vma abbrev_offset)
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{
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abbrev_list * list = (abbrev_list *) xcalloc (sizeof * list, 1);
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list->abbrev_base = abbrev_base;
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list->abbrev_offset = abbrev_offset;
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list->next = abbrev_lists;
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abbrev_lists = list;
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return list;
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}
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static abbrev_list *
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find_abbrev_list_by_abbrev_offset (dwarf_vma abbrev_base,
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dwarf_vma abbrev_offset)
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@ -969,7 +962,7 @@ find_abbrev_list_by_abbrev_offset (dwarf_vma abbrev_base,
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/* Find the abbreviation map for the CU that includes OFFSET.
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OFFSET is an absolute offset from the start of the .debug_info section. */
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/* FIXME: This function is going to slow down readelf & objdump.
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Consider using a better algorithm to mitigate this effect. */
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Not caching abbrevs is likely the answer. */
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static abbrev_map *
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find_abbrev_map_by_offset (dwarf_vma offset)
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@ -1036,40 +1029,18 @@ add_abbrev_attr (unsigned long attribute,
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list->last_abbrev->last_attr = attr;
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}
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/* Processes the (partial) contents of a .debug_abbrev section.
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Returns NULL if the end of the section was encountered.
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Returns the address after the last byte read if the end of
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an abbreviation set was found. */
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/* Return processed (partial) contents of a .debug_abbrev section.
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Returns NULL on errors. */
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static unsigned char *
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static abbrev_list *
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process_abbrev_set (struct dwarf_section *section,
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dwarf_vma abbrev_base,
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dwarf_vma abbrev_size,
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dwarf_vma abbrev_offset,
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abbrev_list *list)
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unsigned char *start,
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unsigned char *end)
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{
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if (abbrev_base >= section->size
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|| abbrev_size > section->size - abbrev_base)
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{
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/* PR 17531: file:4bcd9ce9. */
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warn (_("Debug info is corrupted, abbrev size (%lx) is larger than "
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"abbrev section size (%lx)\n"),
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(unsigned long) (abbrev_base + abbrev_size),
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(unsigned long) section->size);
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return NULL;
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}
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if (abbrev_offset >= abbrev_size)
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{
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warn (_("Debug info is corrupted, abbrev offset (%lx) is larger than "
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"abbrev section size (%lx)\n"),
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(unsigned long) abbrev_offset,
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(unsigned long) abbrev_size);
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return NULL;
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}
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abbrev_list *list = xmalloc (sizeof (*list));
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list->first_abbrev = NULL;
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list->last_abbrev = NULL;
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unsigned char *start = section->start + abbrev_base;
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unsigned char *end = start + abbrev_size;
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start += abbrev_offset;
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while (start < end)
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{
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unsigned long entry;
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@ -1082,14 +1053,18 @@ process_abbrev_set (struct dwarf_section *section,
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/* A single zero is supposed to end the set according
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to the standard. If there's more, then signal that to
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the caller. */
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if (start == end)
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return NULL;
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if (entry == 0)
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return start;
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if (start == end || entry == 0)
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{
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list->start_of_next_abbrevs = start != end ? start : NULL;
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return list;
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}
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READ_ULEB (tag, start, end);
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if (start == end)
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return NULL;
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{
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free (list);
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return NULL;
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}
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children = *start++;
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@ -1124,9 +1099,67 @@ process_abbrev_set (struct dwarf_section *section,
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/* Report the missing single zero which ends the section. */
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error (_("%s section not zero terminated\n"), section->name);
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free (list);
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return NULL;
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}
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/* Return a sequence of abbrevs in SECTION starting at ABBREV_BASE
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plus ABBREV_OFFSET and finishing at ABBREV_BASE + ABBREV_SIZE.
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If FREE_LIST is non-NULL search the already decoded abbrevs on
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abbrev_lists first and if found set *FREE_LIST to NULL. If
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searching doesn't find a matching abbrev, set *FREE_LIST to the
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newly allocated list. If FREE_LIST is NULL, no search is done and
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the returned abbrev_list is always newly allocated. */
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static abbrev_list *
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find_and_process_abbrev_set (struct dwarf_section *section,
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dwarf_vma abbrev_base,
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dwarf_vma abbrev_size,
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dwarf_vma abbrev_offset,
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abbrev_list **free_list)
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{
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if (free_list)
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*free_list = NULL;
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if (abbrev_base >= section->size
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|| abbrev_size > section->size - abbrev_base)
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{
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/* PR 17531: file:4bcd9ce9. */
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warn (_("Debug info is corrupted, abbrev size (%lx) is larger than "
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"abbrev section size (%lx)\n"),
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(unsigned long) (abbrev_base + abbrev_size),
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(unsigned long) section->size);
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return NULL;
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}
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if (abbrev_offset >= abbrev_size)
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{
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warn (_("Debug info is corrupted, abbrev offset (%lx) is larger than "
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"abbrev section size (%lx)\n"),
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(unsigned long) abbrev_offset,
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(unsigned long) abbrev_size);
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return NULL;
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}
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unsigned char *start = section->start + abbrev_base + abbrev_offset;
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unsigned char *end = section->start + abbrev_base + abbrev_size;
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abbrev_list *list = NULL;
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if (free_list)
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list = find_abbrev_list_by_abbrev_offset (abbrev_base, abbrev_offset);
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if (list == NULL)
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{
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list = process_abbrev_set (section, start, end);
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if (list)
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{
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list->abbrev_base = abbrev_base;
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list->abbrev_offset = abbrev_offset;
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list->next = NULL;
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}
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if (free_list)
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*free_list = list;
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}
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return list;
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}
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static const char *
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get_TAG_name (unsigned long tag)
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{
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@ -3671,7 +3704,6 @@ process_debug_info (struct dwarf_section * section,
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dwarf_vma cu_offset;
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unsigned int offset_size;
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struct cu_tu_set * this_set;
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abbrev_list * list;
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unsigned char *end_cu;
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hdrptr = start;
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@ -3727,22 +3759,18 @@ process_debug_info (struct dwarf_section * section,
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abbrev_size = this_set->section_sizes [DW_SECT_ABBREV];
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}
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list = find_abbrev_list_by_abbrev_offset (abbrev_base,
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compunit.cu_abbrev_offset);
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if (list == NULL)
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{
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unsigned char * next;
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list = new_abbrev_list (abbrev_base,
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compunit.cu_abbrev_offset);
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next = process_abbrev_set (&debug_displays[abbrev_sec].section,
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abbrev_base, abbrev_size,
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compunit.cu_abbrev_offset, list);
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list->start_of_next_abbrevs = next;
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}
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abbrev_list *list;
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abbrev_list *free_list;
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list = find_and_process_abbrev_set (&debug_displays[abbrev_sec].section,
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abbrev_base, abbrev_size,
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compunit.cu_abbrev_offset,
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&free_list);
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start = end_cu;
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record_abbrev_list_for_cu (cu_offset, start - section_begin, list);
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if (list != NULL && list->first_abbrev != NULL)
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record_abbrev_list_for_cu (cu_offset, start - section_begin,
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list, free_list);
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else if (free_list != NULL)
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free_abbrev_list (free_list);
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}
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for (start = section_begin, unit = 0; start < end; unit++)
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@ -3758,7 +3786,6 @@ process_debug_info (struct dwarf_section * section,
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struct cu_tu_set *this_set;
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dwarf_vma abbrev_base;
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size_t abbrev_size;
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abbrev_list * list = NULL;
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unsigned char *end_cu;
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hdrptr = start;
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@ -3937,20 +3964,10 @@ process_debug_info (struct dwarf_section * section,
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}
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/* Process the abbrevs used by this compilation unit. */
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list = find_abbrev_list_by_abbrev_offset (abbrev_base,
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compunit.cu_abbrev_offset);
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if (list == NULL)
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{
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unsigned char *next;
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list = new_abbrev_list (abbrev_base,
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compunit.cu_abbrev_offset);
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next = process_abbrev_set (&debug_displays[abbrev_sec].section,
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abbrev_base, abbrev_size,
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compunit.cu_abbrev_offset, list);
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list->start_of_next_abbrevs = next;
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}
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abbrev_list *list;
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list = find_and_process_abbrev_set (&debug_displays[abbrev_sec].section,
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abbrev_base, abbrev_size,
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compunit.cu_abbrev_offset, NULL);
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level = 0;
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last_level = level;
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saved_level = -1;
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@ -4128,6 +4145,8 @@ process_debug_info (struct dwarf_section * section,
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if (entry->children)
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++level;
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}
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if (list != NULL)
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free_abbrev_list (list);
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}
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/* Set num_debug_info_entries here so that it can be used to check if
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@ -6353,24 +6372,15 @@ display_debug_abbrev (struct dwarf_section *section,
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do
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{
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abbrev_list * list;
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dwarf_vma offset;
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offset = start - section->start;
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list = find_abbrev_list_by_abbrev_offset (0, offset);
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dwarf_vma offset = start - section->start;
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abbrev_list *list = find_and_process_abbrev_set (section, 0,
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section->size, offset,
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NULL);
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if (list == NULL)
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{
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list = new_abbrev_list (0, offset);
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start = process_abbrev_set (section, 0, section->size, offset, list);
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list->start_of_next_abbrevs = start;
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}
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else
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start = list->start_of_next_abbrevs;
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break;
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if (list->first_abbrev == NULL)
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continue;
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printf (_(" Number TAG (0x%lx)\n"), (long) offset);
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if (list->first_abbrev)
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printf (_(" Number TAG (0x%lx)\n"), (long) offset);
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for (entry = list->first_abbrev; entry; entry = entry->next)
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{
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@ -6391,6 +6401,8 @@ display_debug_abbrev (struct dwarf_section *section,
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putchar ('\n');
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}
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}
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start = list->start_of_next_abbrevs;
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free_abbrev_list (list);
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}
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while (start);
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