[Bug tree-optimization/59359] New: Segmentation fault in thread_through_all_blocks

[Bug tree-optimization/59359] New: Segmentation fault in thread_through_all_blocks

[antoine.balestrat at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59359

            Bug ID: 59359
           Summary: Segmentation fault in thread_through_all_blocks
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: antoine.balestrat at gmail dot com

Hello !
The following testcase makes GCC 4.9.0 as of 20131201 crash.

$ cat seg.c
int a, b;

void f()
{
    int c = 0;

    for(; b; b++)
    {
        for(a = 0; a; a++);

        unsigned d = 1;

        for(; c < 2; c++)
            if(d = (c = d) < 1)
                return;
    }
}

$ xgcc -O2 -w seg.c
seg.c: In function ‘f’:
seg.c:3:6: internal compiler error: Segmentation fault
 void f()
      ^
0x9901cf crash_signal
        ../../srcdir/gcc/toplev.c:336
0xb33a67 thread_through_all_blocks(bool)
        ../../srcdir/gcc/tree-ssa-threadupdate.c:1652
0xa7a7ab tree_ssa_dominator_optimize
        ../../srcdir/gcc/tree-ssa-dom.c:886
0xa7a7ab execute
        ../../srcdir/gcc/tree-ssa-dom.c:984
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
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From: "burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/57354] Wrong run-time assignment of allocatable array of derived type with allocatable component
Date: Sun, 01 Dec 2013 11:07:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57354

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> ---
(In reply to Paul Thomas from comment #3)
> This patch is preliminary since a temporary is produced, for each
> assignment, copied to the newly reallocated lhs and then deallocated.
> Clearly it would be more efficient to deallocate the lhs and then point the
> lhs to the temporary.

Well, if one has code such as
  a = [a, e]
(and not: "a = [e, a]" or "a = [a, e]*5") one could even do a simple realloc(),
which preserves the data when being extended.

However, one needs to be careful with finalization when using realloc() as both
the LHS and the array constructor would be finalized. (Order: evaluation of the
RHS, finalization of the LHS, assignment, finalization of the RHS [= of the
array constructor/temporaries]. – But that would often involve defined
assignment.)
Note: Finalization of the LHS and of function results + array/structure
constructors after their use is not yet implemented.
>From gcc-bugs-return-436353-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sun Dec 01 11:42:34 2013
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From: "pault at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/58410] [4.8/4.9 Regression] Bogus uninitialized variable warning for allocatable derived type array function result
Date: Sun, 01 Dec 2013 11:42:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idX410

--- Comment #5 from Paul Thomas <pault at gcc dot gnu.org> ---
Author: pault
Date: Sun Dec  1 11:42:25 2013
New Revision: 205566

URL: http://gcc.gnu.org/viewcvs?rev 5566&root=gcc&view=rev
Log:
2013-12-01  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/58410
    * trans-array.c (gfc_alloc_allocatable_for_assignment): Do not
    use the array bounds of an unallocated array but set its size
    to zero instead.

Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/trans-array.c

[Bug tree-optimization/59359] [4.9 Regression] Segmentation fault in thread_through_all_blocks

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59359

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-12-02
                 CC|                            |law at gcc dot gnu.org
   Target Milestone|---                         |4.9.0
            Summary|Segmentation fault in       |[4.9 Regression]
                   |thread_through_all_blocks   |Segmentation fault in
                   |                            |thread_through_all_blocks
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.

[Bug tree-optimization/59359] [4.9 Regression] Segmentation fault in thread_through_all_blocks

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59359

Jeffrey A. Law <law at redhat dot com> changed:

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

--- Comment #2 from Jeffrey A. Law <law at redhat dot com> ---
Confirmed duplicate.

*** This bug has been marked as a duplicate of bug 59322 ***