[forwarded from http://bugs.debian.org/524176]
Matthias
gcc-4.5 with -flto doesn't work with -fPIC properly.
Simple testcase:
int entry(int a)
{
return bar(a)+1;
}
int bar(int a)
{
return a+4;
}
$ gcc-4.5 foo1.c -flto -fPIC -DPIC -c
$ gcc-4.5 foo2.c -flto -fPIC -DPIC -c
$ gcc-4.5 foo1.o foo2.o -flto -shared
/usr/bin/ld: /tmp/ccmA7RCK.lto.o: relocation R_X86_64_PC32 against symbol `bar'
can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status
This works however:
$ gcc-4.5 foo1.o foo2.o -flto -shared -fPIC
Now -fPIC is something libtool automatically adds, and I it doesn't add it at
linktime (perhaps other build systems don't either).
Could gcc's -flto see that all .o files involved in the link are -fPIC... and
make the resulting file -fPIC too?
Or at least it should see the -shared in the linker line, and automatically use
-fPIC when -flto is used.
--
Summary: -flto doesn't remember -fPIC
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: debian-gcc at lists dot debian dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43659
