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Re: [build, driver] RFC: Support compressed debug sections
- From: Rainer Orth <ro at CeBiTec dot Uni-Bielefeld dot DE>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: <gcc-patches at gcc dot gnu dot org>, Paolo Bonzini <bonzini at gnu dot org>
- Date: Tue, 30 Apr 2013 15:59:14 +0200
- Subject: Re: [build, driver] RFC: Support compressed debug sections
- References: <yddvc7tmhx9 dot fsf at lokon dot CeBiTec dot Uni-Bielefeld dot DE> <Pine dot LNX dot 4 dot 64 dot 1304261553200 dot 27966 at digraph dot polyomino dot org dot uk>
"Joseph S. Myers" <joseph@codesourcery.com> writes:
> On Thu, 11 Apr 2013, Rainer Orth wrote:
>
>> +gz=
>> +Common Driver JoinedOrMissing
>> +-gz=<format> Generate compressed debug sections in format <format>
>
> Although handled entirely in specs, I think it's best to use the Enum .opt
> facility to list the valid arguments to this option, so the option
> handling machinery can properly detect invalid arguments. (And, since an
I already wondered how to do this with specs, but your suggestion worked
seamlessly, thanks.
> empty argument isn't meaningful, use Joined rather than JoinedOrMissing.)
Done. This was a leftover from a failed attempt to handle -gz[=format]
in a single clause.
> The integer values assigned to each valid argument string are of course
> arbitrary since nothing will use them.
Right, so I've just used numeric constants.
>> +@item -gz@r{[}=@var{type}@r{]}
>> +@opindex gz
>> +Produce compressed debug sections in DWARF format (if that is
>> +supported). If @var{type} is not given, the default type depends on the
>> +capabilities of the assembler and linker used. @var{type} may be one of
>> +@option{none} (don't compress debug sections), @option{zlib} (use zlib
>> +compression in ELF gABI format), or @option{zlib-gnu} (use zlib
>> +compression in tradition GNU format).
>
> "traditional".
Fixed.
The patch now underwent additonal testing on i386-pc-solaris2.11. The
following tools were handled correctly:
* Solaris as: not yet capable of generating compressed debug sections.
Planned, but command line options not yet known.
* GNU as 2.23.1 built without zlib: just warns about
--compressed-debug-sections, but exits successfully.
* GNU as 2.23.2 with zlib.
* Solaris 11.2 ld: no compressed debug support yet.
* Test version of Solaris 12/11.2 ld: almost final now, command line
option changed to -z compress-sections since the ELF gABI spec allows
compresion of any non-allocable section. I may follow this lead for
gas/gld/gold, so the default for --compress-debug-sections (zlib-gnu)
can remain unchanged, but the --compress-sections default would be
zlib, following the gABI.
* GNU ld 2.23.2: I hadn't realized that gld can decompress on input, but
always produces uncompressed output.
* GNU gold 2.23.2: can read and write compressed sections.
Ok for mainline now?
Thanks.
Rainer
2013-04-10 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
* configure.ac (gcc_cv_as_compress_debug): Check for assembler
compressed debug support.
(gcc_cv_ld_compress_debug): Check for linker compressed debug
support.
* configure: Regenerate.
* config.in: Regenerate.
* common.opt (compressed_debug_sections): New enum.
(gz, gz=): New options.
* gcc.c (LINK_COMPRESS_DEBUG_SPEC, ASM_COMPRESS_DEBUG_SPEC):
Define.
(LINK_COMMAND_SPEC): Invoke LINK_COMPRESS_DEBUG_SPEC.
(asm_options): Invoke ASM_COMPRESS_DEBUG_SPEC.
* opts.c (common_handle_option): Handle OPT_gz, OPT_gz_.
* doc/invoke.texi (Option Summary, Debugging Options): Add
-gz[=type].
(Debugging Options): Document -gz[=type].
# HG changeset patch
# Parent a871a025093e293206f64a1d3b34ac7db53ee187
Enable --compress-debug-sections
diff --git a/gcc/common.opt b/gcc/common.opt
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2407,6 +2407,28 @@ gxcoff+
Common JoinedOrMissing Negative(gcoff)
Generate debug information in extended XCOFF format
+Enum
+Name(compressed_debug_sections) Type(int)
+
+; Since -gz= is completely handled in specs, the values aren't used and we
+; assign arbitrary constants.
+EnumValue
+Enum(compressed_debug_sections) String(none) Value(0)
+
+EnumValue
+Enum(compressed_debug_sections) String(zlib) Value(1)
+
+EnumValue
+Enum(compressed_debug_sections) String(zlib-gnu) Value(2)
+
+gz
+Common Driver
+Generate compressed debug sections
+
+gz=
+Common Driver Joined Enum(compressed_debug_sections)
+-gz=<format> Generate compressed debug sections in format <format>
+
h
Driver Joined Separate
diff --git a/gcc/configure.ac b/gcc/configure.ac
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -4261,6 +4261,30 @@ if test x"$insn" != x; then
[Define if your assembler supports the --debug-prefix-map option.])])
fi
+gcc_GAS_CHECK_FEATURE([compressed debug sections],
+ gcc_cv_as_compress_debug,,,,
+ [# gas compiled without zlib cannot compress debug sections and warns
+ # about it, but still exits successfully. So check for this, too.
+ if $gcc_cv_as --compress-debug-sections -o conftest.o conftest.s 2>&1 | grep -i warning > /dev/null
+ then
+ gcc_cv_as_compress_debug=0
+ elif $gcc_cv_as --compress-debug-sections -o conftest.o conftest.s > /dev/null 2>&1
+ then
+ gcc_cv_as_compress_debug=1
+ gcc_cv_as_compress_debug_option="--compress-debug-sections"
+ gcc_cv_as_no_compress_debug_option="--nocompress-debug-sections"
+ else
+ gcc_cv_as_compress_debug=0
+ # FIXME: Future gas versions will support ELF gABI style via
+ # --compress-debug-sections[=type].
+ fi])
+AC_DEFINE_UNQUOTED(HAVE_AS_COMPRESS_DEBUG, $gcc_cv_as_compress_debug,
+[Define to the level of your assembler's compressed debug section support.])
+AC_DEFINE_UNQUOTED(AS_COMPRESS_DEBUG_OPTION, "$gcc_cv_as_compress_debug_option",
+[Define to the assembler option to enable compressed debug sections.])
+AC_DEFINE_UNQUOTED(AS_NO_COMPRESS_DEBUG_OPTION, "$gcc_cv_as_no_compress_debug_option",
+[Define to the assembler option to disable compressed debug sections.])
+
gcc_GAS_CHECK_FEATURE([.lcomm with alignment], gcc_cv_as_lcomm_with_alignment,
,,
[.lcomm bar,4,16],,
@@ -4531,6 +4555,60 @@ if test x$gcc_cv_ld_eh_gc_sections_bug =
fi
AC_MSG_RESULT($gcc_cv_ld_eh_gc_sections_bug)
+AC_MSG_CHECKING(linker for compressed debug sections)
+# gold/gld support compressed debug sections since binutils 2.19/2.21
+if test $in_tree_ld = yes ; then
+ gcc_cv_ld_compress_debug=0
+ if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 19 -o "$gcc_cv_gld_major_version" -gt 2 \
+ && test $in_tree_ld_is_elf = yes && test $ld_is_gold = yes; then
+ gcc_cv_ld_compress_debug=2
+ gcc_cv_ld_compress_debug_option="--compress-debug-sections"
+ elif test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 21 -o "$gcc_cv_gld_major_version" -gt 2 \
+ && test $in_tree_ld_is_elf = yes; then
+ gcc_cv_ld_compress_debug=1
+ fi
+elif echo "$ld_ver" | grep GNU > /dev/null; then
+ gcc_cv_ld_compress_debug=1
+ if test 0"$ld_date" -lt 20050308; then
+ if test -n "$ld_date"; then
+ # If there was date string, but was earlier than 2005-03-08, fail
+ gcc_cv_ld_compress_debug=0
+ elif test "$ld_vers_major" -lt 2; then
+ gcc_cv_ld_compress_debug=0
+ elif test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 21; then
+ gcc_cv_ld_compress_debug=0
+ fi
+ fi
+ if test $ld_is_gold = yes; then
+ gcc_cv_ld_compress_debug=2
+ gcc_cv_ld_compress_debug_option="--compress-debug-sections"
+ fi
+else
+changequote(,)dnl
+ case "${target}" in
+ *-*-solaris2*)
+ # Introduced in Solaris 11.2.
+ if $gcc_cv_ld --help 2>&1 | grep -- '-z compress-sections' > /dev/null; then
+ gcc_cv_ld_compress_debug=3
+ gcc_cv_ld_compress_debug_option="-z compress-sections"
+ else
+ gcc_cv_ld_compress_debug=0
+ fi
+ ;;
+ *)
+ # Assume linkers other than GNU ld don't support compessed debug
+ # sections.
+ gcc_cv_ld_compress_debug=0
+ ;;
+ esac
+changequote([,])dnl
+fi
+AC_DEFINE_UNQUOTED(HAVE_LD_COMPRESS_DEBUG, $gcc_cv_ld_compress_debug,
+[Define to the level of your linker's compressed debug section support.])
+AC_DEFINE_UNQUOTED(LD_COMPRESS_DEBUG_OPTION, "$gcc_cv_ld_compress_debug_option",
+[Define to the linker option to enable compressed debug sections.])
+AC_MSG_RESULT($gcc_cv_ld_compress_debug)
+
# --------
# UNSORTED
# --------
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -338,7 +338,7 @@ Objective-C and Objective-C++ Dialects}.
-g -g@var{level} -gtoggle -gcoff -gdwarf-@var{version} @gol
-ggdb -grecord-gcc-switches -gno-record-gcc-switches @gol
-gstabs -gstabs+ -gstrict-dwarf -gno-strict-dwarf @gol
--gvms -gxcoff -gxcoff+ @gol
+-gvms -gxcoff -gxcoff+ -gz@r{[}=@var{type}@r{]} @gol
-fno-merge-debug-strings -fno-dwarf2-cfi-asm @gol
-fdebug-prefix-map=@var{old}=@var{new} @gol
-femit-struct-debug-baseonly -femit-struct-debug-reduced @gol
@@ -5072,6 +5072,15 @@ DWARF extensions from later standard ver
Allow using extensions of later DWARF standard version than selected with
@option{-gdwarf-@var{version}}.
+@item -gz@r{[}=@var{type}@r{]}
+@opindex gz
+Produce compressed debug sections in DWARF format (if that is
+supported). If @var{type} is not given, the default type depends on the
+capabilities of the assembler and linker used. @var{type} may be one of
+@option{none} (don't compress debug sections), @option{zlib} (use zlib
+compression in ELF gABI format), or @option{zlib-gnu} (use zlib
+compression in traditional GNU format).
+
@item -gvms
@opindex gvms
Produce debugging information in Alpha/VMS debug format (if that is
diff --git a/gcc/gcc.c b/gcc/gcc.c
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -586,6 +586,32 @@ proper position among the other output f
#define LIBTSAN_EARLY_SPEC ""
#endif
+/* Linker options for compressed debug sections. */
+#if HAVE_LD_COMPRESS_DEBUG == 0
+/* No linker support. */
+#define LINK_COMPRESS_DEBUG_SPEC \
+ " %{gz*:%e-gz is not supported in this configuration}"
+#elif HAVE_LD_COMPRESS_DEBUG == 1
+/* GNU style on input, GNU ld options. */
+#define LINK_COMPRESS_DEBUG_SPEC \
+ " %{gz:%e-gz is not supported in this configuration}" \
+ " %{gz=none:}" \
+ " %{gz=zlib:%e-gz=zlib is not supported in this configuration}" \
+ " %{gz=zlib-gnu:%e-gz=zlib-gnu is not supported in this configuration}"
+#elif HAVE_LD_COMPRESS_DEBUG == 2
+/* GNU style, GNU gold options. */
+#define LINK_COMPRESS_DEBUG_SPEC \
+ " %{gz|gz=zlib-gnu:" LD_COMPRESS_DEBUG_OPTION "=zlib}" \
+ " %{gz=none:" LD_COMPRESS_DEBUG_OPTION "=none}" \
+ " %{gz=zlib:%e-gz=zlib is not supported in this configuration}"
+#else
+/* ELF gABI style. */
+#define LINK_COMPRESS_DEBUG_SPEC \
+ " %{gz|gz=zlib:" LD_COMPRESS_DEBUG_OPTION "=zlib}" \
+ " %{gz=none:" LD_COMPRESS_DEBUG_OPTION "=none}" \
+ " %{gz=zlib-gnu:" LD_COMPRESS_DEBUG_OPTION "=zlib-gnu}"
+#endif
+
/* config.h can define LIBGCC_SPEC to override how and when libgcc.a is
included. */
#ifndef LIBGCC_SPEC
@@ -620,6 +646,25 @@ proper position among the other output f
#define ASM_MAP ""
#endif
+/* Assembler options for compressed debug sections. */
+#if HAVE_AS_COMPRESS_DEBUG == 0
+/* No assembler support. */
+#define ASM_COMPRESS_DEBUG_SPEC \
+ " %{gz*:%e-gz is not supported in this configuration}"
+#elif HAVE_AS_COMPRESS_DEBUG == 1
+/* GNU style, GNU as options. */
+#define ASM_COMPRESS_DEBUG_SPEC \
+ " %{gz|gz=zlib-gnu:" AS_COMPRESS_DEBUG_OPTION "}" \
+ " %{gz=none:" AS_NO_COMPRESS_DEBUG_OPTION "}" \
+ " %{gz=zlib:%e-gz=zlib is not supported in this configuration}"
+#else
+/* ELF gABI style. */
+#define ASM_COMPRESS_DEBUG_SPEC \
+ " %{gz|gz=zlib:" AS_COMPRESS_DEBUG_OPTION "=zlib}" \
+ " %{gz=none:" AS_COMPRESS_DEBUG_OPTION "=none}" \
+ " %{gz=zlib-gnu:" AS_COMPRESS_DEBUG_OPTION "=zlib-gnu}"
+#endif
+
/* Define ASM_DEBUG_SPEC to be a spec suitable for translating '-g'
to the assembler. */
#ifndef ASM_DEBUG_SPEC
@@ -737,8 +782,8 @@ proper position among the other output f
LINK_PLUGIN_SPEC \
"%{flto|flto=*:%<fcompare-debug*} \
%{flto} %{flto=*} %l " LINK_PIE_SPEC \
- "%{fuse-ld=*:-fuse-ld=%*}\
- %X %{o*} %{e*} %{N} %{n} %{r}\
+ "%{fuse-ld=*:-fuse-ld=%*} " LINK_COMPRESS_DEBUG_SPEC \
+ "%X %{o*} %{e*} %{N} %{n} %{r}\
%{s} %{t} %{u*} %{z} %{Z} %{!nostdlib:%{!nostartfiles:%S}}\
%{static:} %{L*} %(mfwrap) %(link_libgcc) " SANITIZER_EARLY_SPEC " %o\
%{fopenmp|ftree-parallelize-loops=*:%:include(libgomp.spec)%(link_gomp)}\
@@ -865,6 +910,7 @@ static const char *asm_options =
to the assembler equivalents. */
"%{v} %{w:-W} %{I*} "
#endif
+ASM_COMPRESS_DEBUG_SPEC
"%a %Y %{c:%W{o*}%{!o*:-o %w%b%O}}%{!c:-o %d%w%u%O}";
static const char *invoke_as =
diff --git a/gcc/opts.c b/gcc/opts.c
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -1750,6 +1750,11 @@ common_handle_option (struct gcc_options
loc);
break;
+ case OPT_gz:
+ case OPT_gz_:
+ /* Handled completely via specs. */
+ break;
+
case OPT_pedantic_errors:
dc->pedantic_errors = 1;
control_warning_option (OPT_Wpedantic, DK_ERROR, value,
--
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University