http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52383
Bug #: 52383
Summary: gcc-4.6 regression: miscompiles Perl on m68k
Classification: Unclassified
Product: gcc
Version: 4.6.2
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: regression
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: t...@mirbsd.org
Created attachment 26753
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26753
gzip’d tarball with preprocessed source and assembler output
Hi,
this was originally reported as:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=658050
The problem is that Perl misbehaves at runtime due to being miscompiled.
It is not reproducible without a native m68k system thus. Sorry about that.
I’ve tracked the problem down to one file. The failure mode is (“cc” is
gcc-4.6):
[…]
cc -c -DPERL_CORE -D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-regmove
-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g -Wall -W -Wextra
-Wdeclaration-after-statement -Wendif-labels -Wc++-compat -Wwrite-strings -fPIC
-DPERL_IS_MINIPERL -DPERL_EXTERNAL_GLOB perlmini.c
LD_LIBRARY_PATH=/tmp/buildd/perl-5.14.2 cc -fstack-protector -L/usr/local/lib
-o miniperl gv.o toke.o perly.o pad.o regcomp.o dump.o util.o mg.o reentr.o
mro.o keywords.o hv.o av.o run.o pp_hot.o sv.o pp.o scope.o pp_ctl.o pp_sys.o
doop.o doio.o regexec.o utf8.o taint.o deb.o universal.o globals.o perlio.o
perlapi.o numeric.o mathoms.o locale.o pp_pack.o pp_sort.o miniperlmain.o
opmini.o perlmini.o -ldl -lm -lpthread -lc -lcrypt
LD_LIBRARY_PATH=/tmp/buildd/perl-5.14.2 ./miniperl -Ilib make_patchnum.pl
Failure yields:
Out of memory during list extend at make_patchnum.pl line 126.
Success yields one of these (the first only once):
Updating 'git_version.h' and 'lib/Config_git.pl'
Reusing 'git_version.h' and 'lib/Config_git.pl'
I’ve attached the results of the following commands:
cc -c -DPERL_CORE -D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-regmove
-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g -Wall -W -Wextra
-Wdeclaration-after-statement -Wendif-labels -Wc++-compat -Wwrite-strings -fPIC
-DPERL_IS_MINIPERL -DPERL_EXTERNAL_GLOB perlmini.c -E -o perlmini.i
gcc-4.6 -S -O1 -fPIC perlmini.i -o perlmini.-O1.s
gcc-4.6 -S -O2 -fPIC perlmini.i -o perlmini.-O2.s
gcc-4.4 -S -O2 -fPIC perlmini.i -o perlmini.4_4.s
The following commands (plus linking and running) will fail:
gcc-4.6 -c -O2 -fPIC perlmini.i
The following commands (plus linking and running) will succeed:
gcc-4.6 -c -O1 -fPIC perlmini.i
gcc-4.4 -c -O2 -fPIC perlmini.i
So this is an optimisation bug (I think) in gcc-4.6 and a regression from
gcc-4.4 (the linking command uses gcc-4.6 in all cases as I’ve not changed it).
Naturally, these are not easily diff’able.
Version information:
gcc-4.6 a.k.a. cc is compiled from Debian 4.6.2-15 sources plus the (second)
bugfix from PR47612:
Using built-in specs.
Target: m68k-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.6-14'
--with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.4 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4
--libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug
--disable-libssp --enable-objc-gc --disable-werror --disable-multilib
--enable-checking=release --build=m68k-linux-gnu --host=m68k-linux-gnu
--target=m68k-linux-gnu
Thread model: posix
gcc version 4.4.6 (Debian 4.4.6-14)
gcc-4.4 is compiled from unmodified Debian sid sources:
Using built-in specs.
Target: m68k-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.6-14'
--with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.4 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4
--libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug
--disable-libssp --enable-objc-gc --disable-werror --disable-multilib
--enable-checking=release --build=m68k-linux-gnu --host=m68k-linux-gnu
--target=m68k-linux-gnu
Thread model: posix
gcc version 4.4.6 (Debian 4.4.6-14)
If you need me to copy out any more files from this chroot, or tar it up
entirely, or run tests; sure, can be done.
