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Fix debug section compression so that it is only performed if it would make the section smaller.

Browse source 
PR binutils/18087
gas	* doc/as.texinfo: Note that when gas compresses debug sections the
	compression is only performed if it makes the section smaller.
	* write.c (compress_debug): Do not compress a debug section if
	doing so would make it larger.

tests	* gas/i386/dw2-compress-1.d: Do not expect the .debug_abbrev or
	.debug_info sections to be compressed.

binu	* doc/binutils.texi: Note that when objcopy compresses debug
	sections the compression is only performed if it makes the section
	smaller.

bfd	* coffgen.c (make_a_section_from_file): Only prepend a z to a
	debug section's name if the section was actually compressed.
	* elf.c (_bfd_elf_make_section_from_shdr): Likewise.
	* compress.c (bfd_init_section_compress_status): Do not compress
	the section if doing so would make it bigger.  In such cases leave
	the section alone and return COMPRESS_SECTION_NONE.
This commit is contained in:
Jon Turney 2015-03-18 15:47:13 +00:00 committed by Nick Clifton
parent 670f82d437
commit 273a49858f
11 changed files with 88 additions and 23 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
bfd/ChangeLog
View file

@ -1,3 +1,14 @@
2015-03-18 Jon Turney <jon.turney@dronecode.org.uk>
Nick Clifton <nickc@redhat.com>
PR binutils/18087
* coffgen.c (make_a_section_from_file): Only prepend a z to a
debug section's name if the section was actually compressed.
* elf.c (_bfd_elf_make_section_from_shdr): Likewise.
* compress.c (bfd_init_section_compress_status): Do not compress
the section if doing so would make it bigger. In such cases leave
the section alone and return COMPRESS_SECTION_NONE.
2015-03-17 Alan Modra <amodra@gmail.com>
* elf64-ppc.c (ppc64_elf_get_synthetic_symtab): Return count of 0

21
bfd/coffgen.c
View file

@ -178,18 +178,21 @@ make_a_section_from_file (bfd *abfd,
abfd, name);
return FALSE;
}
if (name[1] != 'z')
if (return_section->compress_status == COMPRESS_SECTION_DONE)
{
unsigned int len = strlen (name);
if (name[1] != 'z')
{
unsigned int len = strlen (name);
new_name = bfd_alloc (abfd, len + 2);
if (new_name == NULL)
return FALSE;
new_name[0] = '.';
new_name[1] = 'z';
memcpy (new_name + 2, name + 1, len);
new_name = bfd_alloc (abfd, len + 2);
if (new_name == NULL)
return FALSE;
new_name[0] = '.';
new_name[1] = 'z';
memcpy (new_name + 2, name + 1, len);
}
}
break;
break;
case decompress:
if (!bfd_init_section_decompress_status (abfd, return_section))
{

13
bfd/compress.c
View file

@ -441,7 +441,18 @@ bfd_init_section_compress_status (bfd *abfd ATTRIBUTE_UNUSED,
uncompressed_buffer,
uncompressed_size);
free (uncompressed_buffer);
/* PR binutils/18087: If compression didn't make
the section smaller, just keep it uncompressed. */
if (ret && uncompressed_size < sec->size)
{
free (sec->contents);
sec->contents = uncompressed_buffer;
sec->size = uncompressed_size;
sec->compress_status = COMPRESS_SECTION_NONE;
}
else
free (uncompressed_buffer);
return ret;
#endif
}

22
bfd/elf.c
View file

@ -1069,16 +1069,22 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
abfd, name);
return FALSE;
}
if (name[1] != 'z')
/* PR binutils/18087: Compression does not always make a section
smaller. So only rename the section when compression has
actually taken place. */
if (newsect->compress_status == COMPRESS_SECTION_DONE)
{
unsigned int len = strlen (name);
if (name[1] != 'z')
{
unsigned int len = strlen (name);
new_name = bfd_alloc (abfd, len + 2);
if (new_name == NULL)
return FALSE;
new_name[0] = '.';
new_name[1] = 'z';
memcpy (new_name + 2, name + 1, len);
new_name = bfd_alloc (abfd, len + 2);
if (new_name == NULL)
return FALSE;
new_name[0] = '.';
new_name[1] = 'z';
memcpy (new_name + 2, name + 1, len);
}
}
break;
case decompress:

8
binutils/ChangeLog
View file

@ -1,3 +1,11 @@
2015-03-18 Jon Turney <jon.turney@dronecode.org.uk>
Nick Clifton <nickc@redhat.com>
PR binutils/18087
* doc/binutils.texi: Note that when objcopy compresses debug
sections the compression is only performed if it makes the section
smaller.
2015-03-10 H.J. Lu <hongjiu.lu@intel.com>
PR binutils/18101

8
binutils/doc/binutils.texi
View file

@ -1844,10 +1844,14 @@ It can also be a useful way of reducing the size of a @option{--just-symbols}
linker input file.
@item --compress-debug-sections
Compress DWARF debug sections using zlib.
Compress DWARF debug sections using zlib. The debug sections are
renamed to begin with @samp{.zdebug} instead of @samp{.debug}. Note -
if compression would actually make a section @emph{larger} then it is
not compressed or renamed.
@item --decompress-debug-sections
Decompress DWARF debug sections using zlib.
Decompress DWARF debug sections using zlib. The original section
names of the compressed sections are restored.
@item -V
@itemx --version

9
gas/ChangeLog
View file

@ -1,3 +1,12 @@
2015-03-18 Jon Turney <jon.turney@dronecode.org.uk>
Nick Clifton <nickc@redhat.com>
PR binutils/18087
* doc/as.texinfo: Note that when gas compresses debug sections the
compression is only performed if it makes the section smaller.
* write.c (compress_debug): Do not compress a debug section if
doing so would make it larger.
2015-03-17 Ganesh Gopalasubramanian <Ganesh.Gopalasubramanian@amd.com>
* config/tc-i386.c (cpu_arch): Add PROCESSOR_ZNVER flags.

3
gas/doc/as.texinfo
View file

@ -627,7 +627,8 @@ Begin in alternate macro mode.
@item --compress-debug-sections
Compress DWARF debug sections using zlib. The debug sections are renamed
to begin with @samp{.zdebug}, and the resulting object file may not be
compatible with older linkers and object file utilities.
compatible with older linkers and object file utilities. Note if compression
would make a given section @emph{larger} then it is not compressed or renamed.
@item --nocompress-debug-sections
Do not compress DWARF debug sections. This is the default.

7
gas/testsuite/ChangeLog
View file

@ -1,3 +1,10 @@
2015-03-18 Jon Turney <jon.turney@dronecode.org.uk>
Nick Clifton <nickc@redhat.com>
PR binutils/18087
* gas/i386/dw2-compress-1.d: Do not expect the .debug_abbrev or
.debug_info sections to be compressed.
2015-03-17 Ganesh Gopalasubramanian <Ganesh.Gopalasubramanian@amd.com>
* gas/i386/i386.exp: Add new znver1 test cases.

4
gas/testsuite/gas/i386/dw2-compress-1.d
View file

@ -2,7 +2,7 @@
#readelf: -w
#name: DWARF2 debugging information 1
Contents of the .zdebug_info section:
Contents of the .debug_info section:
Compilation Unit @ offset 0x0:
Length: 0x4e \(32-bit\)
@ -31,7 +31,7 @@ Contents of the .zdebug_info section:
<50> DW_AT_encoding : 5 \(signed\)
<1><51>: Abbrev Number: 0
Contents of the .zdebug_abbrev section:
Contents of the .debug_abbrev section:
Number TAG \(0x0\)
1 DW_TAG_compile_unit \[has children\]

5
gas/write.c
View file

@ -1526,6 +1526,11 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
break;
}
/* PR binutils/18087: If compression didn't make
the section smaller, just keep it uncompressed. */
if (compressed_size > sec->size)
return;
/* Replace the uncompressed frag list with the compressed frag list. */
seginfo->frchainP->frch_root = first_newf;
seginfo->frchainP->frch_last = last_newf;