Your message dated Thu, 20 Jun 2019 16:34:01 +0000
with message-id <[email protected]>
and subject line Bug#928214: fixed in gcc-mingw-w64 21.3~deb10u1
has caused the Debian Bug report #928214,
regarding mingw-w64 GCC is built without linker plugin support making LTO
unusable
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
(NB: If you are a system administrator and have no idea what this
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--
928214: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=928214
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: gcc-mingw-w64
Version: 21.2
Hi!
I've discovered that mingw-w64 GCC in Debian is configured without
linker plugin support:
$ x86_64-w64-mingw32-gcc -x c - -flto -fno-fat-lto-objects <<<'int
main() {}'
cc1: error: -fno-fat-lto-objects are supported only with linker plugin
This makes LTO unusable in many real-world cases. Consider the following
example:
$ grep . *.c
foo.c:int foo() {return 42;}
main.c:int main() {return foo();}
$ x86_64-w64-mingw32-gcc -flto -O2 foo.c main.c -c
$ x86_64-w64-mingw32-ar cr app.a main.o foo.o
$ x86_64-w64-mingw32-gcc -flto -O2 app.a
$ x86_64-w64-mingw32-objdump -d a.exe | grep '<main>:' -A 5
0000000000402c30 <main>:
402c30: 48 83 ec 28 sub $0x28,%rsp
402c34: e8 d7 e9 ff ff callq 401610 <__main>
402c39: 90 nop
402c3a: 48 83 c4 28 add $0x28,%rsp
402c3e: e9 0d e9 ff ff jmpq 401550 <foo> # 'foo' is
not inlined
Note that 'foo' is not inlined because the archived object files weren't
processed by LTO (they were processed by the linker as normal objects
because they are "fat" LTO objects, i.e. they contain both normal object
code and GCC IR).
$ x86_64-w64-mingw32-gcc -flto -O2 main.o foo.o
$ x86_64-w64-mingw32-objdump -d a.exe | grep '<main>:' -A 5
0000000000402c30 <main>:
402c30: 48 83 ec 28 sub $0x28,%rsp
402c34: e8 d7 e9 ff ff callq 401610 <__main>
402c39: b8 2a 00 00 00 mov $0x2a,%eax # Good, 'foo'
is inlined!
402c3e: 48 83 c4 28 add $0x28,%rsp
402c42: c3 retq
In this case, legacy LTO implementation was used: GCC driver looked at
the objects and called its 'lto-wrapper' helper. But it can't do that
with archives.
This misconfiguration is caused by the incorrect use of
'--with-plugin-ld' GCC configure option (or its strange behavior,
depending on how you look at it):
$ x86_64-w64-mingw32-gcc -v
Using built-in specs.
COLLECT_GCC=x86_64-w64-mingw32-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-w64-mingw32/8.3-win32/lto-wrapper
Target: x86_64-w64-mingw32
Configured with: ../../src/configure --build=x86_64-linux-gnu
--prefix=/usr --includedir='/usr/include' --mandir='/usr/share/man'
--infodir='/usr/share/info' --sysconfdir=/etc --localstatedir=/var
--disable-silent-rules --libdir='/usr/lib/x86_64-linux-gnu'
--libexecdir='/usr/lib/x86_64-linux-gnu' --disable-maintainer-mode
--disable-dependency-tracking --prefix=/usr --enable-shared
--enable-static --disable-multilib --with-system-zlib
--libexecdir=/usr/lib --without-included-gettext --libdir=/usr/lib
--enable-libstdcxx-time=yes --with-tune=generic
--with-headers=/usr/x86_64-w64-mingw32/include
--enable-version-specific-runtime-libs --enable-fully-dynamic-string
--enable-libgomp --enable-languages=c,c++,fortran,objc,obj-c++,ada
--enable-lto --with-plugin-ld --enable-threads=win32
--program-suffix=-win32 --program-prefix=x86_64-w64-mingw32-
--target=x86_64-w64-mingw32 --with-as=/usr/bin/x86_64-w64-mingw32-as
--with-ld=/usr/bin/x86_64-w64-mingw32-ld --enable-libatomic
--enable-libstdcxx-filesystem-ts=yes
Thread model: win32
gcc version 8.3-win32 20190406 (GCC)
The problem is that "--with-plugin-ld" expects a linker path as the
value, but if it's not given, the value becomes 'yes' and is then tested
for plugin support, without much success (lookup "checking linker plugin
support" in
"https://buildd.debian.org/status/fetch.php?pkg=gcc-mingw-w64&arch=amd64&ver=21.2&stamp=1555227419&raw=0";).
This option is actually not needed since there is no need to use an
"alternative" linker for plugins: the one that is passed with
"--with-ld" will do. I've checked manually that if I remove
"--with-plugin-ld" from the configuration of gcc-mingw-w64 source
package, the linker plugin support is detected properly.
Ubuntu packages are also affected by this problem. I've checked that
OpenSUSE Tumbleweed packages are not affected (they don't use
"--with-plugin-ld").
I suggest to remove "--with-plugin-ld" from GCC configuration options.
Thanks!
-Alexey
--- End Message ---
--- Begin Message ---
Source: gcc-mingw-w64
Source-Version: 21.3~deb10u1
We believe that the bug you reported is fixed in the latest version of
gcc-mingw-w64, which is due to be installed in the Debian FTP archive.
A summary of the changes between this version and the previous one is
attached.
Thank you for reporting the bug, which will now be closed. If you
have further comments please address them to [email protected],
and the maintainer will reopen the bug report if appropriate.
Debian distribution maintenance software
pp.
Stephen Kitt <[email protected]> (supplier of updated gcc-mingw-w64 package)
(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing [email protected])
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Format: 1.8
Date: Thu, 20 Jun 2019 18:07:46 +0200
Source: gcc-mingw-w64
Binary: gcc-mingw-w64 gcc-mingw-w64-i686 gcc-mingw-w64-x86-64 g++-mingw-w64
g++-mingw-w64-i686 g++-mingw-w64-x86-64 gfortran-mingw-w64
gfortran-mingw-w64-i686 gfortran-mingw-w64-x86-64 gobjc-mingw-w64
gobjc-mingw-w64-i686 gobjc-mingw-w64-x86-64 gobjc++-mingw-w64
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gnat-mingw-w64-i686 gnat-mingw-w64-x86-64 gcc-mingw-w64-base
Architecture: source
Version: 21.3~deb10u1
Distribution: buster
Urgency: medium
Maintainer: Stephen Kitt <[email protected]>
Changed-By: Stephen Kitt <[email protected]>
Description:
g++-mingw-w64 - GNU C++ compiler for MinGW-w64
g++-mingw-w64-i686 - GNU C++ compiler for MinGW-w64 targeting Win32
g++-mingw-w64-x86-64 - GNU C++ compiler for MinGW-w64 targeting Win64
gcc-mingw-w64 - GNU C compiler for MinGW-w64
gcc-mingw-w64-base - GNU Compiler Collection for MinGW-w64 (base package)
gcc-mingw-w64-i686 - GNU C compiler for MinGW-w64 targeting Win32
gcc-mingw-w64-x86-64 - GNU C compiler for MinGW-w64 targeting Win64
gfortran-mingw-w64 - GNU Fortran compiler for MinGW-w64
gfortran-mingw-w64-i686 - GNU Fortran compiler for MinGW-w64 targeting Win32
gfortran-mingw-w64-x86-64 - GNU Fortran compiler for MinGW-w64 targeting Win64
gnat-mingw-w64 - GNU Ada compiler for MinGW-w64
gnat-mingw-w64-i686 - GNU Ada compiler for MinGW-w64 targeting Win32
gnat-mingw-w64-x86-64 - GNU Ada compiler for MinGW-w64 targeting Win64
gobjc++-mingw-w64 - GNU Objective-C++ compiler for MinGW-w64
gobjc++-mingw-w64-i686 - GNU Objective-C++ compiler for MinGW-w64 targeting
Win32
gobjc++-mingw-w64-x86-64 - GNU Objective-C++ compiler for MinGW-w64 targeting
Win64
gobjc-mingw-w64 - GNU Objective-C compiler for MinGW-w64
gobjc-mingw-w64-i686 - GNU Objective-C compiler for MinGW-w64 targeting Win32
gobjc-mingw-w64-x86-64 - GNU Objective-C compiler for MinGW-w64 targeting Win64
Closes: 928214
Changes:
gcc-mingw-w64 (21.3~deb10u1) buster; urgency=medium
.
* Upload to Buster.
.
gcc-mingw-w64 (21.3) unstable; urgency=medium
.
* Configure LTO support correctly; thanks Alexey Izbyshev!
Closes: #928214.
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