binutils/binutils-reduce-O-n2-performance-overhead-when-parsing-DWARF.patch

185 lines
4.9 KiB
Diff

From 30cbd32aec30b4bc13427bbd87c4c63c739d4578 Mon Sep 17 00:00:00 2001
From: Steiner H Gunderson <steinar+sourceware@gunderson.no>
Date: Mon, 21 Mar 2022 14:29:12 +0000
Subject: [PATCH] Reduce O(n2) performance overhead when parsing DWARF unit
information.
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.
---
bfd/ChangeLog | 7 ++++
bfd/dwarf2.c | 93 +++++++++++++++++++++++++++++++++------------------
2 files changed, 67 insertions(+), 33 deletions(-)
//diff --git a/bfd/ChangeLog b/bfd/ChangeLog
//index 6ac8b96c57a..fcf5abad5a1 100644
//--- a/bfd/ChangeLog
//+++ b/bfd/ChangeLog
//@@ -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
diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index fdf071c36e9..bb176798f9a 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -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. */
--
2.37.2