re PR tree-optimization/18800 (ivopt missed)

re PR tree-optimization/18800 (ivopt missed)

        PR tree-optimization/18800
        * params.def (PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND): New parameter.
        * tree-ssa-loop-ivopts.c (struct iv_ca): Add n_cands field.
        (ALWAYS_PRUNE_CAND_SET_BOUND): New macro.
        (iv_ca_set_no_cp, iv_ca_set_cp, iv_ca_new): Update n_cands field.
        (iv_ca_delta_join, iv_ca_delta_reverse, iv_ca_n_cands, iv_ca_prune):
        New functions.
        (iv_ca_extend): Return number of candidates in the set.
        (try_add_cand_for): Add argument to iv_ca_extend calls.
        (try_improve_iv_set): Use iv_ca_prune.
        * doc/invoke.texi (iv-always-prune-cand-set-bound): Document.

From-SVN: r92363