[Bug middle-end/108256] New: Missing integer overflow instrumentation when assignment LHS is narrow

[Bug middle-end/108256] New: Missing integer overflow instrumentation when assignment LHS is narrow

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

            Bug ID: 108256
           Summary: Missing integer overflow instrumentation when
                    assignment LHS is narrow
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amonakov at gcc dot gnu.org
  Target Milestone: ---

For

unsigned short f(unsigned short x, unsigned short y)
{
    return x * y;
}

unsigned short g(unsigned short x, unsigned short y)
{
    int r = x * y;
    return r;
}

gcc -O2 -fsanitize=undefined emits instrumentation only for 'g', although both
are equivalent. When 'int r' is changed to 'unsigned short r', 'g' is also not
instrumented.

PR 107912 shows a slightly more complicated variant of this. Affects both C and
C++.

[Bug sanitizer/108256] Missing integer overflow instrumentation when assignment LHS is narrow

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
   Last reconfirmed|                            |2023-01-03
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 54177
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54177&action=edit
gcc13-pr108256.patch

Untested fix.

[Bug sanitizer/108256] Missing integer overflow instrumentation when assignment LHS is narrow

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

--- Comment #2 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:8692b15ae7c05e3224f285069e070c009d9f6efe

commit r13-4988-g8692b15ae7c05e3224f285069e070c009d9f6efe
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Jan 4 10:52:49 2023 +0100

    ubsan: Avoid narrowing of multiply for -fsanitize=signed-integer-overflow
[PR108256]

    We shouldn't narrow multiplications originally done in signed types,
    because the original multiplication might overflow but the narrowed
    one will be done in unsigned arithmetics and will never overflow.

    2023-01-04  Jakub Jelinek  <jakub@redhat.com>

            PR sanitizer/108256
            * convert.cc (do_narrow): Punt for MULT_EXPR if original
            type doesn't wrap around and -fsanitize=signed-integer-overflow
            is on.
            * fold-const.cc (fold_unary_loc) <CASE_CONVERT>: Likewise.

            * c-c++-common/ubsan/pr108256.c: New test.

[Bug sanitizer/108256] Missing integer overflow instrumentation when assignment LHS is narrow

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

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

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

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed on the trunk.

[Bug sanitizer/108256] Missing integer overflow instrumentation when assignment LHS is narrow

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |13.0

[Bug sanitizer/108256] Missing integer overflow instrumentation when assignment LHS is narrow

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jiajing_zheng at 163 dot com

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 113702 has been marked as a duplicate of this bug. ***

[Bug sanitizer/108256] Missing integer overflow instrumentation when assignment LHS is narrow

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |haoxintu at gmail dot com

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 95326 has been marked as a duplicate of this bug. ***

[Bug sanitizer/108256] Missing integer overflow instrumentation when assignment LHS is narrow

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108256

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bic60176 at gmail dot com

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 115155 has been marked as a duplicate of this bug. ***