[Bug debug/46583] New: [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[Bug debug/46583] New: [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

           Summary: [4.6 Regression] -fcompare-debug failure with -O
                    -fno-inline -fipa-cp -fipa-cp-clone
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz


Created attachment 22472
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22472
reduced testcase

Compiler output:
$ gcc -O -fno-inline -fipa-cp -fipa-cp-clone -fcompare-debug testcase.C
gcc: error: testcase.C: -fcompare-debug failure
$ diff testcase.*gkd
46d45
< 0:   const unsigned int D.xxxx;
47a47
> 0:   const unsigned int D.xxxx;

Tested revisions:
r166976 - fail
r165699 - fail
r163636 - fail
r161659 - OK
4.5 r166509 - OK

[Bug debug/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2010.11.21 00:22:11
                 CC|                            |amylaar at spamcop dot net
   Target Milestone|---                         |4.6.0
     Ever Confirmed|0                           |1

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> 2010-11-21 00:22:11 UTC ---
It is caused by revision 162156:

http://gcc.gnu.org/ml/gcc-cvs/2010-07/msg00510.html

[Bug debug/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[amylaar at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |amylaar at gcc dot gnu.org

--- Comment #2 from Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> 2010-11-21 01:35:49 UTC ---
(In reply to comment #1)
> It is caused by revision 162156:
> 
> http://gcc.gnu.org/ml/gcc-cvs/2010-07/msg00510.html

This patch gives a diagnosis for an internal compiler inconsistency.
Having different orders of identifiers can lead to different compilation
output, although if it actually does is down to a complex interaction of
compiler internals that to all effects and purposes can be considered
to be pseudo-random.
See PR44832 for an example.

The real question to be asked here is why the identifier order has changed.

[Bug debug/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[aoliva at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

Alexandre Oliva <aoliva at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |aoliva at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #3 from Alexandre Oliva <aoliva at gcc dot gnu.org> 2010-11-21 07:51:45 UTC ---
Mine.  The order changed because we discarded the typedef decl from the block
scope in the original function.  When the time came to clone it, we'd remap the
typedef type after variable a3 of that type, and a3 would not be nonlocalized,
whereas with debug info we retained the typedef, cloned the type first, and a3
would be nonlocalized.  The patch I'm going to attach momentarily fixes this by
keeping the typedef around.

[Bug debug/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[aoliva at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

--- Comment #4 from Alexandre Oliva <aoliva at gcc dot gnu.org> 2010-11-21 08:06:28 UTC ---
Created attachment 22474
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22474
Patch that fixes the problem

This is the patch I'm testing.

[Bug tree-optimization/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|debug                       |tree-optimization

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2010-11-21 20:46:37 UTC ---
Looks like a sledgehammer.  Why does nonlocalize state depends on debug info?

[Bug tree-optimization/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[aoliva at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

--- Comment #6 from Alexandre Oliva <aoliva at gcc dot gnu.org> 2010-11-22 15:05:33 UTC ---
It checks whether the var type was already remapped.

tree-inline.c:
can_be_nonlocal(...):
  /* We must use global type.  We call remapped_type instead of
     remap_type since we don't want to remap this type here if it
     hasn't been remapped before.  */
  if (TREE_TYPE (decl) != remapped_type (TREE_TYPE (decl), id))
    return false;

[Bug tree-optimization/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-11-22 15:24:04 UTC ---
Yeah.  FYI, I've tried to limit this to VLAs only in
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43942#c14
unfortunately it degraded debug info quality, so for now we really need all
types.

[Bug tree-optimization/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[aoliva at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

--- Comment #8 from Alexandre Oliva <aoliva at gcc dot gnu.org> 2011-01-20 16:56:30 UTC ---
Author: aoliva
Date: Thu Jan 20 16:56:25 2011
New Revision: 169058

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=169058
Log:
gcc/ChangeLog:
PR debug/46583
* tree-ssa-live.c (remove_unused_scope_block_p): Keep type decls.
gcc/testsuite/ChangeLog:
PR debug/46583
* g++.dg/debug/pr46583.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/debug/pr46583.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-live.c

[Bug tree-optimization/46583] [4.6 Regression] -fcompare-debug failure with -O -fno-inline -fipa-cp -fipa-cp-clone

[aoliva at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46583

Alexandre Oliva <aoliva at gcc dot gnu.org> changed:

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

--- Comment #9 from Alexandre Oliva <aoliva at gcc dot gnu.org> 2011-01-20 17:09:11 UTC ---
Fixed