[Bug lto/43659] -flto doesn't remember -fPIC

pinskia at gmail dot com gcc-bugzilla@gcc.gnu.org
Tue Apr 6 03:02:00 GMT 2010



------- Comment #1 from pinskia at gmail dot com  2010-04-06 03:01 -------
Subject: Re:   New: -flto doesn't remember -fPIC

This is done on purpose. The -fpic is needed on the link line too.  
This is a bug in libtool.

Sent from my iPhone

On Apr 5, 2010, at 6:47 PM, "debian-gcc at lists dot debian dot org"
<gcc-bugzilla@gcc.gnu.org 
 > wrote:

> [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
>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43659



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