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May 21, 2012, 3:07 AM
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[perl #113022] Configure misdetects strlcpy et al. with gcc -flto
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# New Ticket Created by l.mai [at] web
# Please include the string: [perl #113022]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=113022 >
This is a bug report for perl from l.mai [at] web,
generated with the help of perlbug 1.39 running under perl 5.16.0.
-----------------------------------------------------------------
[Please describe your issue here]
Hi,
while trying to build perl-5.16.0 I ran into this problem:
...
cgcc -fstack-protector -L/usr/local/lib -O2 -flto -o miniperl \
perlmini.o opmini.o miniperlmain.o 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 -lnsl -ldl -lm -lcrypt -lutil -lc
/tmp/ccn4nr6G.ltrans6.ltrans.o: In function `Perl_sv_usepvn_flags':
ccn4nr6G.ltrans6.o:(.text+0x19c5): undefined reference to `malloc_size'
ccn4nr6G.ltrans6.o:(.text+0x1a8b): undefined reference to `malloc_size'
/tmp/ccn4nr6G.ltrans9.ltrans.o: In function `Perl_find_script':
ccn4nr6G.ltrans9.o:(.text+0x453f): undefined reference to `strlcpy'
/tmp/ccn4nr6G.ltrans9.ltrans.o: In function `Perl_more_bodies':
ccn4nr6G.ltrans9.o:(.text+0x73b7): undefined reference to `malloc_good_size'
/tmp/ccn4nr6G.ltrans25.ltrans.o: In function `Perl_sv_grow':
ccn4nr6G.ltrans25.o:(.text+0x172b): undefined reference to `malloc_size'
ccn4nr6G.ltrans25.o:(.text+0x1760): undefined reference to `malloc_size'
/tmp/ccn4nr6G.ltrans4.ltrans.o: In function `Perl_av_extend':
ccn4nr6G.ltrans4.o:(.text+0x721): undefined reference to `malloc_size'
/tmp/ccn4nr6G.ltrans28.ltrans.o: In function `Perl_magic_set':
ccn4nr6G.ltrans28.o:(.text+0x1ca3): undefined reference to `setproctitle'
ccn4nr6G.ltrans28.o:(.text+0x2659): undefined reference to `setrgid'
ccn4nr6G.ltrans28.o:(.text+0x26d8): undefined reference to `setruid'
collect2: ld returned 1 exit status
make: *** [miniperl] Error 1
This is caused by Configure thinking I have malloc_size, strlcpy, etc. when I
do not.
I was able to fix this problem with the following patch:
--- perl-5.16.0-orig/Configure 2012-04-25 02:18:30.000000000 +0200
+++ perl-5.16.0/Configure 2012-05-15 08:11:20.000000000 +0200
@@ -7782,13 +7782,13 @@
if $contains $tlook $tf >/dev/null 2>&1; then
tval=true;
elif $test "$mistrustnm" = compile -o "$mistrustnm" = run; then
- echo "$extern_C void *$1$tdc; void *(*(p()))$tdc { return &$1; } int main() { if(p()) return(0); else return(1); }"> try.c;
+ echo "$extern_C void *$1$tdc; void *(*(p()))$tdc { return &$1; } int main() { if(p() && p() != (void *)main) return(0); else return(1); }"> try.c;
$cc -o try $optimize $ccflags $ldflags try.c >/dev/null 2>&1 $libs && tval=true;
$test "$mistrustnm" = run -a -x try && { $run ./try$_exe >/dev/null 2>&1 || tval=false; };
$rm_try;
fi;
else
- echo "$extern_C void *$1$tdc; void *(*(p()))$tdc { return &$1; } int main() { if(p()) return(0); else return(1); }"> try.c;
+ echo "$extern_C void *$1$tdc; void *(*(p()))$tdc { return &$1; } int main() { if(p() && p() != (void *)main) return(0); else return(1); }"> try.c;
$cc -o try $optimize $ccflags $ldflags try.c $libs >/dev/null 2>&1 && tval=true;
$rm_try;
fi;
And this is what happened (I think):
Configure thinks I have these symbols because I'm building with -O2 -flto.
"lto" stands for "link-time optimization" and lets gcc apply optimizations in
the linking phase.
The configure test effectively checks whether &foo is NULL. gcc knows that the
address of a symbol can't be NULL, so the test is optimized out.
But that was the only reference to 'p' in the program, so dead code elimination
removes it (and with it the only reference to 'foo').
The program is now effectively 'int main() { return 0; }', so linking succeeds.
End result: Configure thinks the symbols strlcpy, malloc_size, etc exist.
My patch makes it actually check the address so gcc can't get rid of it
completely, thus Configure gets the linker errors it expects.
Andy Dougherty reports that a workaround is to call
./Configure -Doptimize=-O2 [...]
but then call make as
make OPTIMIZE='-O2 -flto'
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=install
severity=medium
---
Site configuration information for perl 5.16.0:
Configured by mauke at Mon May 21 11:48:30 CEST 2012.
Summary of my perl5 (revision 5 version 16 subversion 0) configuration:
Platform:
osname=linux, osvers=2.6.38-gentoo-r6, archname=i686-linux
uname='linux nora 2.6.38-gentoo-r6 #1 preempt sat aug 6 03:05:34 cest 2011 i686 amd athlon(tm) 64 processor 3200+ authenticamd gnulinux '
config_args='-de -Dprefix=/home/mauke/usr/perlbrew/perls/perl-5.16.0'
hint=recommended, useposix=true, d_sigaction=define
useithreads=undef, usemultiplicity=undef
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=undef, use64bitall=undef, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2',
cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.6.3', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
libc=/lib/libc-2.14.1.so, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.14.1'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector'
Locally applied patches:
---
@INC for perl 5.16.0:
/home/mauke/usr/perlbrew/perls/perl-5.16.0/lib/site_perl/5.16.0/i686-linux
/home/mauke/usr/perlbrew/perls/perl-5.16.0/lib/site_perl/5.16.0
/home/mauke/usr/perlbrew/perls/perl-5.16.0/lib/5.16.0/i686-linux
/home/mauke/usr/perlbrew/perls/perl-5.16.0/lib/5.16.0
.
---
Environment for perl 5.16.0:
HOME=/home/mauke
LANG=en_US.UTF-8
LANGUAGE (unset)
LC_COLLATE=POSIX
LD_LIBRARY_PATH=/home/mauke/usr/local/lib
LOGDIR (unset)
PATH=/home/mauke/usr/perlbrew/bin:/home/mauke/usr/perlbrew/perls/perl-5.16.0/bin:/home/mauke/usr/local/bin:/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/i686-pc-linux-gnu/gcc-bin/4.4.5:/opt/sun-jdk-1.4.2.13/bin:/opt/sun-jdk-1.4.2.13/jre/bin:/opt/sun-jdk-1.4.2.13/jre/javaws:/opt/dmd/bin:/usr/games/bin
PERLBREW_HOME=/home/mauke/.perlbrew
PERLBREW_PATH=/home/mauke/usr/perlbrew/bin:/home/mauke/usr/perlbrew/perls/perl-5.16.0/bin
PERLBREW_PERL=perl-5.16.0
PERLBREW_ROOT=/home/mauke/usr/perlbrew
PERLBREW_VERSION=0.27
PERL_BADLANG (unset)
PERL_UNICODE=SAL
SHELL=/bin/bash
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