[Bug tree-optimization/27087] New: [4.1,4.2 regression] ICE in merge_alias_info

[Bug tree-optimization/27087] New: [4.1,4.2 regression] ICE in merge_alias_info

[debian-gcc at lists dot debian dot org]

[ forwarded from http://bugs.debian.org/361501 ]

% cat ice2.c           
extern int ptbl[16];
extern int ctbl[16];

void doViews(void) {
    int *p = ptbl, *c = ctbl;
    while (1) {
        c++;
        p++;
        if (*p && (p != c || *c))
            return;
    }
}

% gcc-4.0 -c -O2 ice2.c
% gcc -c -O2 ice2.c    
ice2.c: In function 'doViews':
ice2.c:4: internal compiler error: in merge_alias_info, at tree-ssa-copy.c:235
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.


-- 
           Summary: [4.1,4.2 regression] ICE in merge_alias_info
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        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=27087

[Bug tree-optimization/27087] [4.1/4.2 regression] ICE in merge_alias_info

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-04-08 23:16 -------
Confirmed, the ICE is during DOM.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at redhat dot com
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |ice-on-valid-code
   Last reconfirmed|0000-00-00 00:00:00         |2006-04-08 23:16:45
               date|                            |
            Summary|[4.1,4.2 regression] ICE in |[4.1/4.2 regression] ICE in
                   |merge_alias_info            |merge_alias_info
   Target Milestone|---                         |4.1.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1/4.2 regression] ICE in merge_alias_info

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-04-09 00:58 -------
Here is a testcase making sure that fold does not get in the way:
extern int ptbl[4];
extern int ctbl[4];

void doViews(void) {
    int  *c = ctbl, *p = ptbl;
    while (1)
  {
        p++;
        c++;
        if (*p)
        {
            if (c == p)
            {
                if (*c)
                    return;
            }
            else
              return;
        }
    }

    g();
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1/4.2 regression] ICE in merge_alias_info

[law at redhat dot com]

------- Comment #3 from law at redhat dot com  2006-04-11 05:41 -------
The problem is that may_propagate_copy and merge_alias_info are inconsistent. 
ie, DOM properly calls may_propagate_copy to determine if a particular copy
propagation is valid.  may_propagate_copy returns true indicating the copy
propagation is valid.  However, when the copy propagation is performed and we
reach merge_alias_info, merge_alias_info has an additional sanity check that
causes it to fail.  

This really isn't a DOM problem.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1/4.2 regression] ICE in merge_alias_info

[law at redhat dot com]

------- Comment #4 from law at redhat dot com  2006-04-11 05:56 -------
Subject: Re:  [4.1/4.2 regression] ICE in
        merge_alias_info

On Sat, 2006-04-08 at 23:16 +0000, pinskia at gcc dot gnu dot org wrote:
> 
> ------- Comment #1 from pinskia at gcc dot gnu dot org  2006-04-08 23:16 -------
> Confirmed, the ICE is during DOM.
As I mentioned in the PR notes, the problem is
tree-ssa-copy.c::may_propagate_copy allows copy propagations which
are rejected by merge_alias_info.  Specifically it allows copy
propagating when the flow-sensitive alias information is not
compatible.

I'm not entirely sure the compatibility check in may_propagate_copy
and merge_alias_info is correct.  It seems to me that we want to 
verify that one is a subset of the other, not just that the two
objects have intersecting flow sensitive information.  Someone
more familiar with this code should follow-up on that issue.

My patch merely makes the two routines consistent in how they handle
flow-sensitive alias information for copy propagations.

Bootstrapped and regression tested on i686-pc-linux-gnu.


------- Comment #5 from law at redhat dot com  2006-04-11 05:56 -------
Created an attachment (id=11241)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11241&action=view)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1/4.2 regression] ICE in merge_alias_info

[law at redhat dot com]

------- Comment #6 from law at redhat dot com  2006-04-13 16:38 -------
Fixed a couple days ago.


-- 

law at redhat dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1 regression] ICE in merge_alias_info

[pinskia at gcc dot gnu dot org]

------- Comment #7 from pinskia at gcc dot gnu dot org  2006-04-13 16:51 -------
But only fixed on the mainline for 4.2 and not for 4.1.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
      Known to fail|                            |4.1.0
      Known to work|                            |4.0.3 4.2.0
         Resolution|FIXED                       |
            Summary|[4.1/4.2 regression] ICE in |[4.1 regression] ICE in
                   |merge_alias_info            |merge_alias_info


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1 regression] ICE in merge_alias_info

[law at redhat dot com]

------- Comment #8 from law at redhat dot com  2006-04-13 17:05 -------
Subject: Re:  [4.1 regression] ICE in
        merge_alias_info

On Thu, 2006-04-13 at 16:51 +0000, pinskia at gcc dot gnu dot org wrote:
> 
> ------- Comment #7 from pinskia at gcc dot gnu dot org  2006-04-13 16:51 -------
> But only fixed on the mainline for 4.2 and not for 4.1.
Feel free to backport the patch to 4.1; I'm not likely to get to it.

jeff


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1 regression] ICE in merge_alias_info

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1 regression] ICE in merge_alias_info

[law at gcc dot gnu dot org]

------- Comment #9 from law at gcc dot gnu dot org  2006-04-18 17:22 -------
Subject: Bug 27087

Author: law
Date: Tue Apr 18 17:22:05 2006
New Revision: 113051

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=113051
Log:
        PR tree-optimization/27087
        * tree-ssa-copy.c (may_propagate_copy): Test flow sensitive
        alias information too.

        * gcc.c-torture/compile/pr27087.c: New test.



Added:
    branches/gcc-4_1-branch/gcc/testsuite/gcc.c-torture/compile/pr27087.c
Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_1-branch/gcc/tree-ssa-copy.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087

[Bug tree-optimization/27087] [4.1 regression] ICE in merge_alias_info

[law at redhat dot com]

------- Comment #10 from law at redhat dot com  2006-04-18 17:24 -------
Patch installed on 4.1 branch too.


-- 

law at redhat dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27087