[Bug analyzer/93281] Various analyzer testsuite failures for 32-bit targets

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93281

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalc...@gcc.gnu.org>:

https://gcc.gnu.org/g:5f0303833d542b273da33e4b149974e739d350e5

commit r10-6039-g5f0303833d542b273da33e4b149974e739d350e5
Author: David Malcolm <dmalc...@redhat.com>
Date:   Wed Jan 15 15:55:11 2020 -0500

    analyzer: fix handling of negative byte offsets (v2) (PR 93281)

    Various 32-bit targets show failures in gcc.dg/analyzer/data-model-1.c
    with tests of the form:
      __analyzer_eval (q[-2].x == 107024); /* { dg-warning "TRUE" } */
      __analyzer_eval (q[-2].y == 107025); /* { dg-warning "TRUE" } */
    where they emit UNKNOWN instead.

    The root cause is that gimple has a byte-based twos-complement offset
    of -16 expressed like this:
      _55 = q_92 + 4294967280;  (32-bit)
    or:
      _55 = q_92 + 18446744073709551600; (64-bit)

    Within region_model::convert_byte_offset_to_array_index that unsigned
    offset was being divided by the element size to get an offset within
    an array.

    This happened to work on 64-bit target and host, but not elsewhere;
    the offset needs to be converted to a signed type before the division
    is meaningful.

    This patch does so, fixing the failures.

    gcc/analyzer/ChangeLog:
        PR analyzer/93281
        * region-model.cc
        (region_model::convert_byte_offset_to_array_index): Convert to
        ssizetype before dividing by byte_size.  Use fold_binary rather
        than fold_build2 to avoid needlessly constructing a tree for the
        non-const case.