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Reduce O(n2) performance overhead when parsing DWARF unit information.

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PR 28978
	* dwarf2.c (scan_unit_for_symbols): When performing second pass,
	check to see if the function or variable being processed is the
	same as the previous one.
This commit is contained in:
Steiner H Gunderson 2022-03-21 14:29:12 +00:00 committed by Nick Clifton
parent 46fb6d5aa2
commit 30cbd32aec
2 changed files with 67 additions and 33 deletions
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7
bfd/ChangeLog
View File

@ -1,3 +1,10 @@
2022-03-21 Steiner H Gunderson <steinar+sourceware@gunderson.no>
PR 28978
* dwarf2.c (scan_unit_for_symbols): When performing second pass,
check to see if the function or variable being processed is the
same as the previous one.
2022-03-18 Viorel Preoteasa <viorel.preoteasa@gmail.com>
PR 28924

93
bfd/dwarf2.c
View File

@ -3293,6 +3293,36 @@ lookup_var_by_offset (bfd_uint64_t offset, struct varinfo * table)
/* DWARF2 Compilation unit functions. */
static struct funcinfo *
reverse_funcinfo_list (struct funcinfo *head)
{
struct funcinfo *rhead;
struct funcinfo *temp;
for (rhead = NULL; head; head = temp)
{
temp = head->prev_func;
head->prev_func = rhead;
rhead = head;
}
return rhead;
}
static struct varinfo *
reverse_varinfo_list (struct varinfo *head)
{
struct varinfo *rhead;
struct varinfo *temp;
for (rhead = NULL; head; head = temp)
{
temp = head->prev_var;
head->prev_var = rhead;
rhead = head;
}
return rhead;
}
/* Scan over each die in a comp. unit looking for functions to add
to the function table and variables to the variable table. */
@ -3308,7 +3338,9 @@ scan_unit_for_symbols (struct comp_unit *unit)
struct funcinfo *func;
} *nested_funcs;
int nested_funcs_size;
struct funcinfo *last_func;
struct varinfo *last_var;
/* Maintain a stack of in-scope functions and inlined functions, which we
can use to set the caller_func field. */
nested_funcs_size = 32;
@ -3442,10 +3474,16 @@ scan_unit_for_symbols (struct comp_unit *unit)
}
}
unit->function_table = reverse_funcinfo_list (unit->function_table);
unit->variable_table = reverse_varinfo_list (unit->variable_table);
/* This is the second pass over the abbrevs. */
info_ptr = unit->first_child_die_ptr;
nesting_level = 0;
last_func = NULL;
last_var = NULL;
while (nesting_level >= 0)
{
unsigned int abbrev_number, i;
@ -3481,16 +3519,32 @@ scan_unit_for_symbols (struct comp_unit *unit)
|| abbrev->tag == DW_TAG_entry_point
|| abbrev->tag == DW_TAG_inlined_subroutine)
{
func = lookup_func_by_offset (current_offset, unit->function_table);
if (last_func
&& last_func->prev_func
&& last_func->prev_func->unit_offset == current_offset)
func = last_func->prev_func;
else
func = lookup_func_by_offset (current_offset, unit->function_table);
if (func == NULL)
goto fail;
last_func = func;
}
else if (abbrev->tag == DW_TAG_variable
|| abbrev->tag == DW_TAG_member)
{
var = lookup_var_by_offset (current_offset, unit->variable_table);
if (last_var
&& last_var->prev_var
&& last_var->prev_var->unit_offset == current_offset)
var = last_var->prev_var;
else
var = lookup_var_by_offset (current_offset, unit->variable_table);
if (var == NULL)
goto fail;
last_var = var;
}
for (i = 0; i < abbrev->num_attrs; ++i)
@ -3684,6 +3738,9 @@ scan_unit_for_symbols (struct comp_unit *unit)
}
}
unit->function_table = reverse_funcinfo_list (unit->function_table);
unit->variable_table = reverse_varinfo_list (unit->variable_table);
free (nested_funcs);
return true;
@ -4047,36 +4104,6 @@ comp_unit_find_line (struct comp_unit *unit,
linenumber_ptr);
}
static struct funcinfo *
reverse_funcinfo_list (struct funcinfo *head)
{
struct funcinfo *rhead;
struct funcinfo *temp;
for (rhead = NULL; head; head = temp)
{
temp = head->prev_func;
head->prev_func = rhead;
rhead = head;
}
return rhead;
}
static struct varinfo *
reverse_varinfo_list (struct varinfo *head)
{
struct varinfo *rhead;
struct varinfo *temp;
for (rhead = NULL; head; head = temp)
{
temp = head->prev_var;
head->prev_var = rhead;
rhead = head;
}
return rhead;
}
/* Extract all interesting funcinfos and varinfos of a compilation
unit into hash tables for faster lookup. Returns TRUE if no
errors were enountered; FALSE otherwise. */