[Bug middle-end/24295] New: [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[Bug middle-end/24295] New: [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[rguenth at gcc dot gnu dot org]

Consider

static const double foo_local = 1.0;
#pragma weak foo = foo_local

with unit-at-a-time we get rid of the foo_local variable (because it is unused
apart form the weak decl).  This is a regression from 4.0 where we correctly
mark foo_local as referenced.

This breaks building Xorg.  rth fixed it for 4.0, somehow the bug came back.


-- 
           Summary: [4.1 Regression] #pragma weak foo = bar  no longer
                    causes bar to be referenced
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P2
         Component: middle-end
        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=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2005-10-10 12:18 -------
Confirmed, be failing since at least 20050827.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
      Known to fail|                            |4.1.0
      Known to work|                            |4.0.3
   Last reconfirmed|0000-00-00 00:00:00         |2005-10-10 12:18:19
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2005-10-10 12:19 -------
See PR19031 where this problem was fixed for 4.0.0.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2005-10-10 13:55 -------
Failing started before 20050801.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2005-10-10 14:11 -------
And has been failing since 20050701.

Maybe we need a machine which just builds a distro over and over.  I know Apple
has a such a beast for Mac OS X.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2005-10-10 14:32 -------
Happens in 20050601 also.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #6 from pinskia at gcc dot gnu dot org  2005-10-10 14:43 -------
Happens also in 20050501.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #7 from pinskia at gcc dot gnu dot org  2005-10-10 14:57 -------
Fails with 20050401 also.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #8 from pinskia at gcc dot gnu dot org  2005-10-10 15:08 -------
Works in 20050320.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #9 from pinskia at gcc dot gnu dot org  2005-10-10 15:15 -------
CCing Honza since the tree profiling branch merge happened during that time.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #10 from pinskia at gcc dot gnu dot org  2005-10-10 15:27 -------
Works with 20050321.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #11 from pinskia at gcc dot gnu dot org  2005-10-10 15:37 -------
Works on 20050325.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #12 from pinskia at gcc dot gnu dot org  2005-10-10 15:37 -------
(In reply to comment #11)
> Works on 20050325.

The top of the changelog at this time is:
2005-03-24  Kazu Hirata  <kazu@cs.umass.edu>

        * emit-rtl.c (reverse_comparison): Remove.
        * rtl.h: Remove the corresponding prototype.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #13 from pinskia at gcc dot gnu dot org  2005-10-10 15:50 -------
Works with 20050328.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #14 from pinskia at gcc dot gnu dot org  2005-10-10 15:52 -------
(In reply to comment #13)
> Works with 20050328.
Note the top of the changelog is:
2005-03-27  Steven Bosscher  <stevenb@suse.de>

        * vax-protos.h (vax_output_int_move, vax_output_int_add,
        vax_output_conditional_branch): New prototypes.


I don't think this was caused by the merge of the tree-profiling after all.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

------- Comment #15 from pinskia at gcc dot gnu dot org  2005-10-10 15:57 -------
I am starting to think the following patch caused it:
-2005-03-29  Jakub Jelinek  <jakub@redhat.com>
-
-       PR middle-end/20622
-       * cgraph.h (struct cgraph_varpool_node): Add alias field.
-       * cgraph.c (cgraph_varpool_assemble_pending_decls): Don't call
-       assemble_variable on aliases.
-       * varasm.c (assemble_alias): Set node->alias.
-       * toplev.c (wrapup_global_declarations): Don't call
-       rest_of_decl_compilation on aliases again.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[janis at gcc dot gnu dot org]

------- Comment #16 from janis at gcc dot gnu dot org  2005-10-10 23:31 -------
A regression hunt identified this patch from hubicka on 2005-03-30:

  http://gcc.gnu.org/ml/gcc-cvs/2005-03/msg01487.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] #pragma weak foo = bar no longer causes bar to be referenced

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |critical


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced

[steven at gcc dot gnu dot org]

------- Comment #17 from steven at gcc dot gnu dot org  2005-10-18 22:24 -------
We want to cgraph_varpool_mark_needed_node the rhs of the #pragma weak, but by
the time we get to maybe_apply_pending_pragma_weaks, we only have the
identifier, and AFAICT no way to find the appropriate symbol that we want to
mark as needed.

Here, I've just made the pragma handler force the rhs of the #pragma weak into
the assembler file.  Without force_output, the "unreferenced" rhs will still be
dropped from the cgraph by cgraph_varpool_remove_unreferenced_decls, and there
is no way to tell from there that this variable is needed, other than forcing
it to be written out.  This is a hack, but the way we find out about necessary
nodes is so complicated that I don't fully understand how this is supposed to
be fixed.

I think fixing this completely requires that we keep a list of DECLs instead of
IDENTIFIER_NODEs for the pending #pragma weak list, so that we can mark the
DECL of pending pragmas from maybe_apply_pragma_weak.  Or maybe there is
another way to get the DECL for alias_id there?


Index: c-pragma.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/c-pragma.c,v
retrieving revision 1.91
diff -u -3 -p -r1.91 c-pragma.c
--- c-pragma.c  19 Jul 2005 20:19:12 -0000      1.91
+++ c-pragma.c  18 Oct 2005 22:23:57 -0000
@@ -36,6 +36,7 @@ Software Foundation, 51 Franklin Street,
 #include "tm_p.h"
 #include "vec.h"
 #include "target.h"
+#include "cgraph.h"

 #define GCC_BAD(gmsgid) \
   do { warning (OPT_Wpragmas, gmsgid); return; } while (0)
@@ -310,7 +311,7 @@ maybe_apply_pending_pragma_weaks (void)
       alias_id = TREE_PURPOSE (t);
       id = TREE_VALUE (t);

-      if (TREE_VALUE (t) == NULL)
+      if (id == NULL)
        continue;

       decl = build_decl (FUNCTION_DECL, alias_id, default_function_type);
@@ -330,6 +331,7 @@ handle_pragma_weak (cpp_reader * ARG_UNU
 {
   tree name, value, x, decl;
   enum cpp_ttype t;
+  struct cgraph_varpool_node *node;

   value = 0;

@@ -354,6 +356,15 @@ handle_pragma_weak (cpp_reader * ARG_UNU
     }
   else
     pending_weaks = tree_cons (name, value, pending_weaks);
+
+  decl = identifier_global_value (value);
+  if (decl && DECL_P (decl))
+    {
+      /* Force DECL into the assembler output no matter what.  */
+      node = cgraph_varpool_node (decl);
+      cgraph_varpool_mark_needed_node (node);
+      node->force_output = true;
+    }
 }
 #else
 void


-- 

steven at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jsm28 at gcc dot gnu dot org
   Last reconfirmed|2005-10-10 12:18:19         |2005-10-18 22:24:55
               date|                            |
            Summary|[4.1 Regression] #pragma    |[4.1 Regression] Xorg
                   |weak foo = bar  no longer   |broken, #pragma weak foo =
                   |causes bar to be referenced |bar no longer causes bar to
                   |                            |be referenced


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced

[rguenth at gcc dot gnu dot org]

------- Comment #18 from rguenth at gcc dot gnu dot org  2005-10-19 09:31 -------
+  decl = identifier_global_value (value);

Make that

+  decl = decl ? identifier_global_value (value) : NULL_TREE;

and it even survives bootstrap.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced

[rguenth at gcc dot gnu dot org]

------- Comment #19 from rguenth at gcc dot gnu dot org  2005-10-19 09:32 -------
err, s/decl/value/ of course.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced

[aoliva at gcc dot gnu dot org]

-- 

aoliva at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |aoliva at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-10-18 22:24:55         |2005-10-20 18:35:38
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced

[cvs-commit at gcc dot gnu dot org]

------- Comment #20 from cvs-commit at gcc dot gnu dot org  2005-10-20 19:30 -------
Subject: Bug 24295

CVSROOT:        /cvs/gcc
Module name:    gcc
Changes by:     aoliva@gcc.gnu.org      2005-10-20 19:30:23

Modified files:
        gcc/testsuite  : ChangeLog 
        gcc            : ChangeLog cgraphunit.c varasm.c 
        gcc/testsuite/g++.old-deja/g++.abi: vtable2.C 
Added files:
        gcc/testsuite/gcc.dg: attr-alias-3.c 
        gcc/testsuite/gcc.dg/weak: weak-14.c 

Log message:
        gcc/ChangeLog:
        PR middle-end/24295
        * cgraphunit.c (cgraph_varpool_remove_unreferenced_decls): Mark
        alias targets.
        * varasm.c (find_decl_and_mark_needed): After cgraph global info
        is ready, stop marking functions, but still mark variables.
        gcc/testsuite/ChangeLog:
        PR middle-end/24295
        * g++.old-deja/g++.abi/vtable2.C: Do not introduce external
        declarations with the same names as thunks' alias targets, use
        aliases instead.
        * gcc.dg/attr-alias-3.c: New test.
        * gcc.dg/weak/weak-14.c, gcc.dg/weak/weak-14a.c: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.6219&r2=1.6220
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.10193&r2=2.10194
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cgraphunit.c.diff?cvsroot=gcc&r1=1.129&r2=1.130
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/varasm.c.diff?cvsroot=gcc&r1=1.533&r2=1.534
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.old-deja/g++.abi/vtable2.C.diff?cvsroot=gcc&r1=1.7&r2=1.8
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/attr-alias-3.c.diff?cvsroot=gcc&r1=NONE&r2=1.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/weak/weak-14.c.diff?cvsroot=gcc&r1=NONE&r2=1.1


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced

[aoliva at gcc dot gnu dot org]

------- Comment #21 from aoliva at gcc dot gnu dot org  2005-10-20 19:32 -------
Fixed.


-- 

aoliva at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295

[Bug middle-end/24295] [4.1 Regression] Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced

[cvs-commit at gcc dot gnu dot org]

------- Comment #22 from cvs-commit at gcc dot gnu dot org  2005-10-25 18:59 -------
Subject: Bug 24295

CVSROOT:        /cvs/gcc
Module name:    gcc
Changes by:     aoliva@gcc.gnu.org      2005-10-25 18:59:21

Modified files:
        gcc/testsuite  : ChangeLog 
        gcc/testsuite/g++.old-deja/g++.abi: vtable2.C 

Log message:
        PR middle-end/24295, PR testsuite/24477
        * g++.old-deja/g++.abi/vtable2.C: Require alias for now.  Will be
        removed when weakref hits the tree.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.6252&r2=1.6253
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.old-deja/g++.abi/vtable2.C.diff?cvsroot=gcc&r1=1.8&r2=1.9


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24295