From: Fangrui Song <maskray@google.com>
To: Andrew Pinski <pinskia@gmail.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
"H.J. Lu" <hjl.tools@gmail.com>,
Rainer Orth <ro@cebitec.uni-bielefeld.de>,
Fangrui Song <i@maskray.me>
Subject: Re: [PATCH] Remove legacy -gz=zlib-gnu
Date: Fri, 1 Jul 2022 00:20:57 -0700 [thread overview]
Message-ID: <20220701072057.f2ojdm4pdm5257ni@google.com> (raw)
In-Reply-To: <CA+=Sn1nfQ-9NxSgY-rt2JP4kP_ydtE3F2RFpWmav9x204n_qFw@mail.gmail.com>
On 2022-07-01, Andrew Pinski wrote:
>On Thu, Jun 30, 2022 at 11:58 PM Fangrui Song via Gcc-patches
><gcc-patches@gcc.gnu.org> wrote:
>>
>> From: Fangrui Song <i@maskray.me>
>>
>> SHF_COMPRESSED style zlib has been supported since binutils 2.26
>> and the legacy zlib-gnu option hasn't gain adoption.
>> According to Debian Code Search (`gz=zlib-gnu`), no project uses
>> -gz=zlib-gnu (valgrind has a configure to use -gz=zlib).
>> Remove support for the legacy zlib-gnu and simplify configure.ac by
>> removing zlib-gnu ld/as check.
>
>A couple of things, you are missing a changelog.
Sorry.
>Second, why remove something which is still working?
It's unused and its existence causes confusion: the paradox of choice.
People may assume the support may be good but newer DWARF consumers may
not support the legacy format.
The other motivation is to clean up it a bit. I foresee that someone
will add --compress-debug-sections=zstd to binutils and configure.ac and
gcc/gcc.cc would become more messy.
>Third, why not just make gz=zlib-gnu as an alias to gz=zlib instead so
>if someone used it before it will still work. we try not to remove
>options; have them emit a warning and be ignored (or moved over to the
>closed option).
Changing the semantics of -gz=zlib-gnu would be even more confusing.
>Thanks,
>Andrew
>
>> ---
>> gcc/common.opt | 3 ---
>> gcc/configure | 33 ++++++---------------------------
>> gcc/configure.ac | 29 ++++-------------------------
>> gcc/doc/invoke.texi | 11 +++++------
>> gcc/gcc.cc | 22 ++--------------------
>> 5 files changed, 17 insertions(+), 81 deletions(-)
>>
>> diff --git a/gcc/common.opt b/gcc/common.opt
>> index e7a51e882ba..8754d93d545 100644
>> --- a/gcc/common.opt
>> +++ b/gcc/common.opt
>> @@ -3424,9 +3424,6 @@ 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.
>> diff --git a/gcc/configure b/gcc/configure
>> index 62872d132ea..ca87e875e9d 100755
>> --- a/gcc/configure
>> +++ b/gcc/configure
>> @@ -19674,7 +19674,7 @@ else
>> lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>> lt_status=$lt_dlunknown
>> cat > conftest.$ac_ext <<_LT_EOF
>> -#line 19679 "configure"
>> +#line 19677 "configure"
>> #include "confdefs.h"
>>
>> #if HAVE_DLFCN_H
>> @@ -19780,7 +19780,7 @@ else
>> lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>> lt_status=$lt_dlunknown
>> cat > conftest.$ac_ext <<_LT_EOF
>> -#line 19785 "configure"
>> +#line 19783 "configure"
>> #include "confdefs.h"
>>
>> #if HAVE_DLFCN_H
>> @@ -29711,20 +29711,13 @@ else
>> 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
>> - # Since binutils 2.26, gas supports --compress-debug-sections=type,
>> + # Since binutils 2.26, gas supports --compress-debug-sections=zlib,
>> # defaulting to the ELF gABI format.
>> - elif $gcc_cv_as --compress-debug-sections=zlib-gnu -o conftest.o conftest.s > /dev/null 2>&1
>> + elif $gcc_cv_as --compress-debug-sections=zlib -o conftest.o conftest.s > /dev/null 2>&1
>> then
>> gcc_cv_as_compress_debug=2
>> gcc_cv_as_compress_debug_option="--compress-debug-sections"
>> gcc_cv_as_no_compress_debug_option="--nocompress-debug-sections"
>> - # Before binutils 2.26, gas only supported --compress-debug-options and
>> - # emitted the traditional GNU format.
>> - 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
>> fi
>> @@ -30238,42 +30231,28 @@ $as_echo "$gcc_cv_ld_eh_gc_sections_bug" >&6; }
>>
>> { $as_echo "$as_me:${as_lineno-$LINENO}: checking linker for compressed debug sections" >&5
>> $as_echo_n "checking linker for compressed debug sections... " >&6; }
>> -# gold/gld support compressed debug sections since binutils 2.19/2.21
>> -# In binutils 2.26, gld gained support for the ELF gABI format.
>> +# GNU ld/gold support --compressed-debug-sections=zlib since binutils 2.26.
>> if test $in_tree_ld = yes ; then
>> gcc_cv_ld_compress_debug=0
>> if test $ld_is_mold = yes; then
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> - elif test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 19 -o "$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 "$gcc_cv_gld_minor_version" -ge 26 -o "$gcc_cv_gld_major_version" -gt 2 \
>> && test $in_tree_ld_is_elf = yes && test $ld_is_gold = no; then
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> - elif test "$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
>> if test $ld_is_mold = yes; then
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> elif test "$ld_vers_major" -lt 2 \
>> - || test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 21; then
>> + || test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 26; then
>> gcc_cv_ld_compress_debug=0
>> - elif test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 26; then
>> - gcc_cv_ld_compress_debug=1
>> else
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> fi
>> - if test $ld_is_gold = yes; then
>> - gcc_cv_ld_compress_debug=2
>> - gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> - fi
>> else
>> case "${target}" in
>> *-*-solaris2*)
>> diff --git a/gcc/configure.ac b/gcc/configure.ac
>> index 446747311a6..f40f75271c2 100644
>> --- a/gcc/configure.ac
>> +++ b/gcc/configure.ac
>> @@ -5733,20 +5733,13 @@ gcc_GAS_CHECK_FEATURE([compressed debug sections],
>> 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
>> - # Since binutils 2.26, gas supports --compress-debug-sections=type,
>> + # Since binutils 2.26, gas supports --compress-debug-sections=zlib,
>> # defaulting to the ELF gABI format.
>> - elif $gcc_cv_as --compress-debug-sections=zlib-gnu -o conftest.o conftest.s > /dev/null 2>&1
>> + elif $gcc_cv_as --compress-debug-sections=zlib -o conftest.o conftest.s > /dev/null 2>&1
>> then
>> gcc_cv_as_compress_debug=2
>> gcc_cv_as_compress_debug_option="--compress-debug-sections"
>> gcc_cv_as_no_compress_debug_option="--nocompress-debug-sections"
>> - # Before binutils 2.26, gas only supported --compress-debug-options and
>> - # emitted the traditional GNU format.
>> - elif $gcc_cv_as --compress-debug-sections -o conftest.o conftest.s > /dev/null 2>&1
>> - then
>> - gcc_cv_as_compress_debug=1
>> - gcc_cv_as_compress_debug_option="--compress-debug-sections"
>> - gcc_cv_as_no_compress_debug_option="--nocompress-debug-sections"
>> else
>> gcc_cv_as_compress_debug=0
>> fi])
>> @@ -6131,42 +6124,28 @@ fi
>> AC_MSG_RESULT($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
>> -# In binutils 2.26, gld gained support for the ELF gABI format.
>> +# GNU ld/gold support --compressed-debug-sections=zlib since binutils 2.26.
>> if test $in_tree_ld = yes ; then
>> gcc_cv_ld_compress_debug=0
>> if test $ld_is_mold = yes; then
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> - elif test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -ge 19 -o "$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 "$gcc_cv_gld_minor_version" -ge 26 -o "$gcc_cv_gld_major_version" -gt 2 \
>> && test $in_tree_ld_is_elf = yes && test $ld_is_gold = no; then
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> - elif test "$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
>> if test $ld_is_mold = yes; then
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> elif test "$ld_vers_major" -lt 2 \
>> - || test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 21; then
>> + || test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 26; then
>> gcc_cv_ld_compress_debug=0
>> - elif test "$ld_vers_major" -eq 2 -a "$ld_vers_minor" -lt 26; then
>> - gcc_cv_ld_compress_debug=1
>> else
>> gcc_cv_ld_compress_debug=3
>> gcc_cv_ld_compress_debug_option="--compress-debug-sections"
>> 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
>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>> index 757775ea576..467659cb094 100644
>> --- a/gcc/doc/invoke.texi
>> +++ b/gcc/doc/invoke.texi
>> @@ -10775,12 +10775,11 @@ location views are enabled.
>> 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
>> -@samp{none} (don't compress debug sections), @samp{zlib} (use zlib
>> -compression in ELF gABI format), or @samp{zlib-gnu} (use zlib
>> -compression in traditional GNU format). If the linker doesn't support
>> -writing compressed debug sections, the option is rejected. Otherwise,
>> -if the assembler does not support them, @option{-gz} is silently ignored
>> -when producing object files.
>> +@samp{none} (don't compress debug sections), or @samp{zlib} (use zlib
>> +compression in ELF gABI format). If the linker doesn't support writing
>> +compressed debug sections, the option is rejected. Otherwise, if the
>> +assembler does not support them, @option{-gz} is silently ignored when
>> +producing object files.
>>
>> @item -femit-struct-debug-baseonly
>> @opindex femit-struct-debug-baseonly
>> diff --git a/gcc/gcc.cc b/gcc/gcc.cc
>> index 5cbb38560b2..660cd6f4ef4 100644
>> --- a/gcc/gcc.cc
>> +++ b/gcc/gcc.cc
>> @@ -827,22 +827,11 @@ proper position among the other output files. */
>> /* 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. Reject, not useful. */
>> -#define LINK_COMPRESS_DEBUG_SPEC \
>> - " %{gz*:%e-gz 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} "
>> #elif HAVE_LD_COMPRESS_DEBUG == 3
>> /* 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} "
>> + " %{gz=none:" LD_COMPRESS_DEBUG_OPTION "=none}"
>> #else
>> #error Unknown value for HAVE_LD_COMPRESS_DEBUG.
>> #endif
>> @@ -891,18 +880,11 @@ proper position among the other output files. */
>> /* No assembler support. Ignore silently. */
>> #define ASM_COMPRESS_DEBUG_SPEC \
>> " %{gz*:} "
>> -#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} "
>> #elif HAVE_AS_COMPRESS_DEBUG == 2
>> /* 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} "
>> + " %{gz=none:" AS_COMPRESS_DEBUG_OPTION "=none}"
>> #else
>> #error Unknown value for HAVE_AS_COMPRESS_DEBUG.
>> #endif
>> --
>> 2.37.0.rc0.161.g10f37bed90-goog
>>
next prev parent reply other threads:[~2022-07-01 7:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-01 6:57 Fangrui Song
2022-07-01 7:03 ` Andrew Pinski
2022-07-01 7:20 ` Fangrui Song [this message]
2022-09-20 12:55 ` Martin Liška
2022-09-21 7:36 ` Richard Biener
2022-09-21 7:45 ` Fangrui Song
2022-09-21 7:49 ` Martin Liška
2022-09-21 9:35 ` Richard Biener
2022-09-22 11:10 ` [PATCH] remove -gz=zlib-gnu option value Martin Liška
2022-09-22 12:26 ` [PATCH v2] " Martin Liška
2022-09-22 12:35 ` Richard Biener
2022-09-22 12:51 ` [PATCH] support -gz=zstd for both linker and assembler Martin Liška
2022-09-27 13:54 ` Martin Liška
2022-09-28 19:21 ` Richard Biener
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