[Bug sanitizer/81601] [8/9/10 Regression] incorrect Warray-bounds warning with -fsanitize

[Bug sanitizer/81601] [8/9/10 Regression] incorrect Warray-bounds warning with -fsanitize

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601

--- Comment #27 from Jeffrey A. Law <law at redhat dot com> ---
So I just prototyped a bit of code that might help with this BZ.

This seems better suited for match.pd, except that match.pd doesn't seem to
want to handle BIT_FIELD_REF nodes.  So I did the prototype in forwprop.

Given a BIT_AND_EXPR which just masks off high bits that is fed by a
BIT_FIELD_REF, we can adjust the # of bits in the BIT_FIELD_REF and the type of
the reference.  The BIT_AND turns into a nop-conversion.

So the key blocks start like this:

;;   basic block 2, loop depth 0, maybe hot
;;    prev block 0, next block 3, flags: (NEW, VISITED)
;;    pred:       ENTRY (FALLTHRU,EXECUTABLE)
  _13 = __builtin_object_size (tp_11(D), 0);
  _14 = &tp_11(D)->D.2292;
  .UBSAN_OBJECT_SIZE (_14, 13, _13, 0);
  _1 = tp_11(D)->chrono_type;
  _2 = (int) _1;
  if (_1 == 0)
    goto <bb 3>; [INV]
  else
    goto <bb 5>; [INV]
;;    succ:       3 (TRUE_VALUE,EXECUTABLE)
;;                5 (FALSE_VALUE,EXECUTABLE)

;;   basic block 3, loop depth 0, maybe hot
;;    prev block 2, next block 4, flags: (NEW, VISITED)
;;    pred:       2 (TRUE_VALUE,EXECUTABLE)
  _3 = BIT_FIELD_REF <*tp_11(D), 8, 96>;
  _4 = _3 & 3;
  if (_4 != 0)
    goto <bb 4>; [INV]
  else
    goto <bb 5>; [INV]
;;    succ:       4 (TRUE_VALUE,EXECUTABLE)
;;                5 (FALSE_VALUE,EXECUTABLE)

And the bits in block #3 turn into:

;;   basic block 3, loop depth 0, maybe hot
;;    prev block 2, next block 4, flags: (NEW, VISITED)
;;    pred:       2 (TRUE_VALUE,EXECUTABLE)
  _9 = BIT_FIELD_REF <*tp_11(D), 2, 96>;
  _4 = (unsigned char) _9;
  if (_9 != 0)
    goto <bb 4>; [INV]
  else
    goto <bb 5>; [INV]
;;    succ:       4 (TRUE_VALUE,EXECUTABLE)
;;                5 (FALSE_VALUE,EXECUTABLE)


That's good enough that FRE can see the redundancy between tp->chrono_type and
the BIT_FIELD_REF and all the right things just happen from that point onward.

[Bug sanitizer/81601] [9/10/11/12 Regression] incorrect Warray-bounds warning with -fsanitize

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|8.5                         |9.4

--- Comment #28 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 8 branch is being closed.

[Bug sanitizer/81601] [9/10/11/12 Regression] incorrect Warray-bounds warning with -fsanitize

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.4                         |9.5

--- Comment #29 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9.4 is being released, retargeting bugs to GCC 9.5.

[Bug sanitizer/81601] [10/11/12/13 Regression] incorrect Warray-bounds warning with -fsanitize

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.5                         |10.4

--- Comment #30 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed

[Bug sanitizer/81601] [10/11/12/13 Regression] incorrect Warray-bounds warning with -fsanitize

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.4                        |10.5

--- Comment #31 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.

[Bug sanitizer/81601] [11/12/13/14 Regression] incorrect Warray-bounds warning with -fsanitize

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81601

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #32 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.