amd64/127640: GCC will not build shared libraries with -fprofile-generate on amd64

[John Baldwin]

The following reply was made to PR amd64/127640; it has been noted by GNATS.

From: John Baldwin <jhb at freebsd.org>
To: freebsd-amd64 at freebsd.org
Cc: Jonathan Briggs <zlynx at acm.org>, freebsd-gnats-submit at freebsd.org
Subject: Re: amd64/127640: GCC will not build shared libraries with -fprofile-generate on amd64
Date: Fri, 26 Sep 2008 10:01:43 -0400

 On Thursday 25 September 2008 04:50:43 pm Jonathan Briggs wrote:
 > 
 > >Number:         127640
 > >Category:       amd64
 > >Synopsis:       GCC will not build shared libraries with -fprofile-generate 
 on amd64
 > >Confidential:   no
 > >Severity:       non-critical
 > >Priority:       low
 > >Responsible:    freebsd-amd64
 > >State:          open
 > >Quarter:        
 > >Keywords:       
 > >Date-Required:
 > >Class:          sw-bug
 > >Submitter-Id:   current-users
 > >Arrival-Date:   Thu Sep 25 21:00:03 UTC 2008
 > >Closed-Date:
 > >Last-Modified:
 > >Originator:     Jonathan Briggs
 > >Release:        7.0-RELEASE
 > >Organization:
 > >Environment:
 > FreeBSD freebsd64 7.0-RELEASE FreeBSD 7.0-RELEASE #0: Sun Feb 24 10:35:36 
 UTC 2008     root at driscoll.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  
 amd64
 > 
 > >Description:
 > I was porting a specialized database library to FreeBSD and the build failed 
 with this error:
 > 
 > /usr/bin/ld: /usr/lib/libgcov.a(_gcov_merge_add.o): relocation R_X86_64_32 
 can not be used when making a shared object; recompile with -fPIC
 > /usr/lib/libgcov.a: could not read symbols: Bad value
 > 
 > The library uses -fprofile-generate, runs a test set, then rebuilds 
 with -fprofile-use.  It's worth a few ms per lookup.
 > 
 > Also, this builds very well on i386 FreeBSD 7.0 and on many varieties of 
 Linux and their GCC builds (Debian ia64, Gentoo amd64, CentOS 5.2, Fedora 5, 
 8, 9).
 > 
 > I can work around the problem by just not doing a profile build.
 > >How-To-Repeat:
 > Put the following in a shell script:
 > 
 > #!/bin/sh
 > cat <<EOF |
 > #include <stdio.h>
 > 
 > int counter(int count)
 > {
 > 	int i;
 > 
 > 	for(i=0; i<count; i++) {
 > 		printf("loop %d\n", i);
 > 	}
 > 	return i;
 > }
 > EOF
 > gcc -O2 -shared -fprofile-generate -fPIC -o t1.so -x c -
 
 What if you add -fPIC as the message suggests?
 
 -- 
 John Baldwin