[Bug lto/40721] New: [LTO] complains about two tentative definitions

[Bug lto/40721] New: [LTO] complains about two tentative definitions

[rguenth at gcc dot gnu dot org]

This breaks a lot of benchmarks in SPEC CPU 2000.

t.c

int i;

t2.c

int i;
int main() { return i; }

$ ./xgcc -B. -o t t1.c t2.c
$ ./xgcc -B. -o t t1.c t2.c -flto
t2.c:1:5: error: 'i' has already been defined
t1.c:1:5: error: previously defined here
lto-wrapper: ././xgcc returned 1 exit status
collect2: lto-wrapper returned 1 exit status

the LTO behavior is wrong for C.  The testcase would violate the C++ ODR, but
LTO should not reject the valid C program (note ODR violations do not need to
be diagnosed).


-- 
           Summary: [LTO] complains about two tentative definitions
           Product: gcc
           Version: lto
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: lto
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721

[Bug lto/40721] [LTO] complains about two tentative definitions

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2009-07-11 17:53 -------
Cases like

t1.c
int i = 2;

t2.c
int i = 1;
int main() { return i; }

are diagnosed by the linker - not ideal, but not different from -fno-lto
either.


Index: lto-symtab.c
===================================================================
--- lto-symtab.c        (revision 149512)
+++ lto-symtab.c        (working copy)
@@ -568,15 +568,17 @@ lto_symtab_merge_decl (tree new_decl,
   if (resolution == LDPR_PREVAILING_DEF
       || resolution == LDPR_PREVAILING_DEF_IRONLY)
     {
-      if (old_resolution == LDPR_PREVAILING_DEF
-         || old_resolution == LDPR_PREVAILING_DEF_IRONLY)
+      if ((old_resolution == LDPR_PREVAILING_DEF
+          || old_resolution == LDPR_PREVAILING_DEF_IRONLY)
+         && old_resolution != resolution)
        {
          error ("%J%qD has already been defined", new_decl, new_decl);
          error ("%Jpreviously defined here", old_decl);
          return;
        }
       gcc_assert (old_resolution == LDPR_PREEMPTED_IR
-                 || old_resolution ==  LDPR_RESOLVED_IR);
+                 || old_resolution ==  LDPR_RESOLVED_IR
+                 || old_resolution == resolution);
       lto_symtab_set_identifier_decl (name, new_decl);
       return;
     }


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721

[Bug lto/40721] [LTO] complains about two tentative definitions

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2009-07-11 18:05 -------
Note this is only true for the non -fno-common case.  Really this is an
extension to the standard C language but we should support it.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721

[Bug lto/40721] [LTO] complains about two tentative definitions

[rguenther at suse dot de]

------- Comment #3 from rguenther at suse dot de  2009-07-11 18:09 -------
Subject: Re:  [LTO] complains about two tentative
 definitions

On Sat, 11 Jul 2009, pinskia at gcc dot gnu dot org wrote:

> ------- Comment #2 from pinskia at gcc dot gnu dot org  2009-07-11 18:05 -------
> Note this is only true for the non -fno-common case.  Really this is an
> extension to the standard C language but we should support it.

You mean it is only true for -fcommon (which is the default)?

Richard.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721

[Bug lto/40721] [LTO] complains about two tentative definitions

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2009-07-11 18:19 -------
(In reply to comment #3)
> Subject: Re:  [LTO] complains about two tentative
>  definitions
> 
> On Sat, 11 Jul 2009, pinskia at gcc dot gnu dot org wrote:
> 
> > ------- Comment #2 from pinskia at gcc dot gnu dot org  2009-07-11 18:05 -------
> > Note this is only true for the non -fno-common case.  Really this is an
> > extension to the standard C language but we should support it.
> 
> You mean it is only true for -fcommon (which is the default)?

What I write is the same as what your wrote (I had  two negatives ;) .

-- Pinski


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721

[Bug lto/40721] [LTO] complains about two tentative definitions

[bje at gcc dot gnu dot org]

------- Comment #5 from bje at gcc dot gnu dot org  2009-07-13 05:27 -------
Confirmed.


-- 

bje at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-07-13 05:27:24
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721

[Bug lto/40721] [LTO] complains about two tentative definitions

[rguenth at gcc dot gnu dot org]

------- Comment #6 from rguenth at gcc dot gnu dot org  2009-07-13 13:42 -------
Subject: Bug 40721

Author: rguenth
Date: Mon Jul 13 13:42:03 2009
New Revision: 149587

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149587
Log:
2009-07-13  Richard Guenther  <rguenther@suse.de>

        PR lto/40721
        * lto-opts.c (register_user_option_p): Handle OPT_fcommon.
        (handle_common_option): Likewise.
        * lto-symtab.c (lto_symtab_merge_decl): Merge re-definitions
        if flag_no_common is not set.

Modified:
    branches/lto/gcc/ChangeLog.lto
    branches/lto/gcc/lto-opts.c
    branches/lto/gcc/lto-symtab.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721

[Bug lto/40721] [LTO] complains about two tentative definitions

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2009-07-13 13:43 -------
Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40721