[Bug tree-optimization/64058] [5/6 Regression] Performance degradation after r216304

["law at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64058

--- Comment #21 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Author: law
Date: Wed Mar 23 13:20:16 2016
New Revision: 234425

URL: https://gcc.gnu.org/viewcvs?rev=234425&root=gcc&view=rev
Log:
        PR tree-optimization/64058
        * tree-ssa-coalesce.c (struct coalesce_pair): Add new field
        CONFLICT_COUNT.
        (struct ssa_conflicts): Move up earlier in the file.
        (conflicts_, var_map_): New static variables.
        (initialize_conflict_count): New function to initialize the
        CONFLICT_COUNT field for each conflict pair.
        (compare_pairs): Lazily initialize the conflict count and use it
        as the first tie-breaker.
        (sort_coalesce_list): Add new arguments conflicts, map.  Initialize
        and wipe conflicts_ and map_ around the call to qsort.  Remove
        special case for 2 coalesce pairs.
        * bitmap.c (bitmap_count_unique_bits): New function.
        (bitmap_count_bits_in_word): New function, extracted from
        bitmap_count_bits.
        (bitmap_count_bits): Use bitmap_count_bits_in_word.
        * bitmap.h (bitmap_count_unique_bits): Declare it.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/bitmap.c
    trunk/gcc/bitmap.h
    trunk/gcc/tree-ssa-coalesce.c