re PR middle-end/90796 (GCC: O2 vs O3 output differs on simple test)

re PR middle-end/90796 (GCC: O2 vs O3 output differs on simple test)

Fix PR90796

       PR middle-end/90796
       * gimple-loop-jam.c (any_access_function_variant_p): New function.
       (adjust_unroll_factor): Use it to constrain safety, new parameter.
       (tree_loop_unroll_and_jam): Adjust call and profitable unroll factor.

testsuite/
       Backport from mainline
       PR middle-end/90796
       * gcc.dg/unroll-and-jam.c: Disable loop-invariant motion and adjust.

       PR middle-end/90796
       * gcc.dg/unroll-and-jam.c: Add three invalid and one valid case.

From-SVN: r278512