[gold patch] Fix --strip-debug-gdb and --gdb-index to strip appropriate debug sections
Cary Coutant
ccoutant@google.com
Wed Jun 6 23:53:00 GMT 2012
Gold has various options for stripping subsets of debug sections, but
there are a couple of problems and one enhancement I'd like to make:
(1) The --strip-debug-gdb option does not correctly handle compressed
debug sections (it checks only for ".debug_").
(2) We don't recognize the recently-added ".debug_macro" section.
(3) The --gdb-index option should automatically strip the
".debug_pubnames", ".debug_pubtypes", and ".debug_aranges" sections,
for which the ".gdb_index" section is meant to be a replacement.
This patch addresses these three issues.
Tested on x86_64. OK?
-cary
2012-06-06 Cary Coutant <ccoutant@google.com>
* layout.cc (gdb_sections): Remove ".debug_" prefixes,
add .debug_macro.
(lines_only_debug_sections): Likewise.
(gdb_fast_lookup_sections): New static array.
(is_gdb_debug_section): Rename formal parameter.
(is_lines_only_debug_section): Likewise.
(is_gdb_fast_lookup_section): New function.
(Layout::include_section): Check for ".zdebug_" prefix; pass
section name suffix to is_gdb_debug_section, et al.; check for
fast-lookup sections when building .gdb_index.
* options.h (--strip-debug-gdb): Update GDB version number.
commit 89fbc279316739fb0def4dd6554b9dc73f1d3667
Author: Cary Coutant <ccoutant@google.com>
Date: Wed Jun 6 15:57:32 2012 -0700
Fix --strip-debug-gdb to work with compressed debug sections;
automatically strip pubnames, pubtypes, and aranges sections when
generating .gdb_index; add .debug_macro to list of gdb sections.
diff --git a/gold/layout.cc b/gold/layout.cc
index c7ca322..154be88 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -453,60 +453,98 @@ Layout::Hash_key::operator()(const Layout::Key& k) const
return k.first + k.second.first + k.second.second;
}
-// Returns whether the given section is in the list of
-// debug-sections-used-by-some-version-of-gdb. Currently,
-// we've checked versions of gdb up to and including 7.4.
+// These are the debug sections that are actually used by gdb.
+// Currently, we've checked versions of gdb up to and including 7.4.
+// We only check the part of the name that follows ".debug_" or
+// ".zdebug_".
static const char* gdb_sections[] =
-{ ".debug_abbrev",
- ".debug_addr", // Fission extension
- // ".debug_aranges", // not used by gdb as of 7.4
- ".debug_frame",
- ".debug_info",
- ".debug_types",
- ".debug_line",
- ".debug_loc",
- ".debug_macinfo",
- // ".debug_pubnames", // not used by gdb as of 7.4
- // ".debug_pubtypes", // not used by gdb as of 7.4
- ".debug_ranges",
- ".debug_str",
+{
+ "abbrev",
+ "addr", // Fission extension
+ // "aranges", // not used by gdb as of 7.4
+ "frame",
+ "info",
+ "types",
+ "line",
+ "loc",
+ "macinfo",
+ "macro",
+ // "pubnames", // not used by gdb as of 7.4
+ // "pubtypes", // not used by gdb as of 7.4
+ "ranges",
+ "str",
};
+// This is the minimum set of sections needed for line numbers.
+
static const char* lines_only_debug_sections[] =
-{ ".debug_abbrev",
- // ".debug_addr", // Fission extension
- // ".debug_aranges", // not used by gdb as of 7.4
- // ".debug_frame",
- ".debug_info",
- // ".debug_types",
- ".debug_line",
- // ".debug_loc",
- // ".debug_macinfo",
- // ".debug_pubnames", // not used by gdb as of 7.4
- // ".debug_pubtypes", // not used by gdb as of 7.4
- // ".debug_ranges",
- ".debug_str",
+{
+ "abbrev",
+ // "addr", // Fission extension
+ // "aranges", // not used by gdb as of 7.4
+ // "frame",
+ "info",
+ // "types",
+ "line",
+ // "loc",
+ // "macinfo",
+ // "macro",
+ // "pubnames", // not used by gdb as of 7.4
+ // "pubtypes", // not used by gdb as of 7.4
+ // "ranges",
+ "str",
+};
+
+// These sections are the DWARF fast-lookup tables, and are not needed
+// when building a .gdb_index section.
+
+static const char* gdb_fast_lookup_sections[] =
+{
+ "aranges",
+ "pubnames",
+ "pubtypes",
};
+// Returns whether the given debug section is in the list of
+// debug-sections-used-by-some-version-of-gdb. SUFFIX is the
+// portion of the name following ".debug_" or ".zdebug_".
+
static inline bool
-is_gdb_debug_section(const char* str)
+is_gdb_debug_section(const char* suffix)
{
// We can do this faster: binary search or a hashtable. But why bother?
for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
- if (strcmp(str, gdb_sections[i]) == 0)
+ if (strcmp(suffix, gdb_sections[i]) == 0)
return true;
return false;
}
+// Returns whether the given section is needed for lines-only debugging.
+
static inline bool
-is_lines_only_debug_section(const char* str)
+is_lines_only_debug_section(const char* suffix)
{
// We can do this faster: binary search or a hashtable. But why bother?
for (size_t i = 0;
i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
++i)
- if (strcmp(str, lines_only_debug_sections[i]) == 0)
+ if (strcmp(suffix, lines_only_debug_sections[i]) == 0)
+ return true;
+ return false;
+}
+
+// Returns whether the given section is a fast-lookup section that
+// will not be needed when building a .gdb_index section.
+
+static inline bool
+is_gdb_fast_lookup_section(const char* suffix)
+{
+ // We can do this faster: binary search or a hashtable. But why bother?
+ for (size_t i = 0;
+ i < sizeof(gdb_fast_lookup_sections)/sizeof(*gdb_fast_lookup_sections);
+ ++i)
+ if (strcmp(suffix, gdb_fast_lookup_sections[i]) == 0)
return true;
return false;
}
@@ -583,16 +621,34 @@ Layout::include_section(Sized_relobj_file<size,
big_endian>*, const char* name,
&& (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
{
// Debugging sections can only be recognized by name.
- if (is_prefix_of(".debug", name)
- && !is_lines_only_debug_section(name))
+ if (is_prefix_of(".debug_", name)
+ && !is_lines_only_debug_section(name + 7))
+ return false;
+ if (is_prefix_of(".zdebug_", name)
+ && !is_lines_only_debug_section(name + 8))
return false;
}
if (parameters->options().strip_debug_gdb()
&& (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
{
// Debugging sections can only be recognized by name.
- if (is_prefix_of(".debug", name)
- && !is_gdb_debug_section(name))
+ if (is_prefix_of(".debug_", name)
+ && !is_gdb_debug_section(name + 7))
+ return false;
+ if (is_prefix_of(".zdebug_", name)
+ && !is_gdb_debug_section(name + 8))
+ return false;
+ }
+ if (parameters->options().gdb_index()
+ && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
+ {
+ // When building .gdb_index, we can strip .debug_pubnames,
+ // .debug_pubtypes, and .debug_aranges sections.
+ if (is_prefix_of(".debug_", name)
+ && is_gdb_fast_lookup_section(name + 7))
+ return false;
+ if (is_prefix_of(".zdebug_", name)
+ && is_gdb_fast_lookup_section(name + 8))
return false;
}
if (parameters->options().strip_lto_sections()
diff --git a/gold/options.h b/gold/options.h
index b244bd5..0138ed5 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -1002,7 +1002,7 @@ class General_options
N_("Emit only debug line number information"), NULL);
DEFINE_bool(strip_debug_gdb, options::TWO_DASHES, '\0', false,
N_("Strip debug symbols that are unused by gdb "
- "(at least versions <= 6.7)"), NULL);
+ "(at least versions <= 7.4)"), NULL);
DEFINE_bool(strip_lto_sections, options::TWO_DASHES, '\0', true,
N_("Strip LTO intermediate code sections"), NULL);
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