[Bug tree-optimization/101145] niter analysis fails for until-wrap condition

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101145

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jiu Fu Guo <guojiufu@gcc.gnu.org>:

https://gcc.gnu.org/g:3673dcf6d6baeb67bb70ff03d4cb3f92beed0075

commit r12-3136-g3673dcf6d6baeb67bb70ff03d4cb3f92beed0075
Author: Jiufu Guo <guojiufu@linux.ibm.com>
Date:   Wed Jul 7 13:41:01 2021 +0800

    Analyze niter for until-wrap condition [PR101145]

    For code like:
    unsigned foo(unsigned val, unsigned start)
    {
      unsigned cnt = 0;
      for (unsigned i = start; i > val; ++i)
        cnt++;
      return cnt;
    }

    The number of iterations should be about UINT_MAX - start.

    There is function adjust_cond_for_loop_until_wrap which
    handles similar work for const bases.
    Like adjust_cond_for_loop_until_wrap, this patch enhance
    function number_of_iterations_cond/number_of_iterations_lt
    to analyze number of iterations for this kind of loop.

    gcc/ChangeLog:

    2021-08-25  Jiufu Guo  <guojiufu@linux.ibm.com>

            PR tree-optimization/101145
            * tree-ssa-loop-niter.c (number_of_iterations_until_wrap):
            New function.
            (number_of_iterations_lt): Invoke above function.
            (adjust_cond_for_loop_until_wrap):
            Merge to number_of_iterations_until_wrap.
            (number_of_iterations_cond): Update invokes for
            adjust_cond_for_loop_until_wrap and number_of_iterations_lt.

    gcc/testsuite/ChangeLog:

    2021-08-25  Jiufu Guo  <guojiufu@linux.ibm.com>

            PR tree-optimization/101145
            * gcc.dg/vect/pr101145.c: New test.
            * gcc.dg/vect/pr101145.inc: New test.
            * gcc.dg/vect/pr101145_1.c: New test.
            * gcc.dg/vect/pr101145_2.c: New test.
            * gcc.dg/vect/pr101145_3.c: New test.
            * gcc.dg/vect/pr101145inf.c: New test.
            * gcc.dg/vect/pr101145inf.inc: New test.
            * gcc.dg/vect/pr101145inf_1.c: New test.