[Bug c/98378] New: new valgrind error for ./gcc.c-torture/execute/pr60960.c

[Bug c/98378] New: new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

            Bug ID: 98378
           Summary: new valgrind error for
                    ./gcc.c-torture/execute/pr60960.c
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Last week's valgrind build of trunk gcc, hash 97b56dece7413839,
compiled ./gcc.c-torture/execute/pr60960.c fine.

This week's valgrind build of trunk gcc, hash dc00689332f023d9
doesn't. This is what it does:

==471616== Conditional jump or move depends on uninitialised value(s)
==471616==    at 0x15CF3B5: (anonymous
namespace)::find_bswap_or_nop_finalize((anonymous namespace)::symbolic_number*,
unsigned long*, unsigned long*) (gimple-ssa-store-merging.c:807)

Source code gimple-ssa-store-merging.c:807 is

  if (n->base_addr)

Flag -O2 used on source code file gcc.c-torture/execute/pr60960.c

[Bug c/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

--- Comment #1 from David Binderman <dcb314 at hotmail dot com> ---
git bisect in progress. Trying hash f23753c710d54fdf.

[Bug c/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

--- Comment #2 from David Binderman <dcb314 at hotmail dot com> ---
Looks good. Trying 0dd48296433763ba

[Bug c/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

--- Comment #3 from David Binderman <dcb314 at hotmail dot com> ---
Looks bad. Trying 571d3fb1f40fa85c

[Bug c/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

--- Comment #4 from David Binderman <dcb314 at hotmail dot com> ---
Looks bad. Trying 5137d1ae6a1fe4a3

[Bug c/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

David Binderman <dcb314 at hotmail dot com> changed:

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

--- Comment #5 from David Binderman <dcb314 at hotmail dot com> ---
I am struggling to make further progress with this one.

Commit cd676dfa57e643a4f7d8445e6ebad0f21cf3fd84 looks suspicious,
since it is the only one that changes anything in compiler source code
file gimple-ssa-store-merging.c in the good .. bad range.

Jakub, your best advice sought, please.

[Bug c/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

--- Comment #6 from David Binderman <dcb314 at hotmail dot com> ---
Testsuite file ./gcc.c-torture/execute/simd-6.c, with flag -O2,
has similar problems with a valgrind version of gcc trunk.

[Bug tree-optimization/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:9032d2b2414ed22e53a9980a51b835d3caf83c48

commit r11-6269-g9032d2b2414ed22e53a9980a51b835d3caf83c48
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sat Dec 19 12:46:40 2020 +0100

    bswap: Fix up a thinko with empty CONSTRUCTORs [PR98378]

    The code I've added recently in find_bswap_or_nop for VECTOR CONSTRUCTORs
    is missing punt on an important case - namely empty CONSTRUCTORs, because
in that
    case the loop will not initialize *n and the code after the loop will then
    use the uninitialized structure.

    2020-12-19  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/98378
            * gimple-ssa-store-merging.c (find_bswap_or_nop): Punt if
CONSTRUCTOR
            has no elements.

[Bug tree-optimization/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

--- Comment #8 from David Binderman <dcb314 at hotmail dot com> ---
I can provide, if requested, a list of other testsuite files
that fail in the same way.

This might be a good sanity check for Jakub's fix.

Otherwise, I suggest that this bug could be marked as fixed.

[Bug tree-optimization/98378] new valgrind error for ./gcc.c-torture/execute/pr60960.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98378

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

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

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
.