[Bug target/94042] [10 Regression] Bootstrap fails on ppc-linux-gnu

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94042

--- Comment #50 from Martin Liška <marxin at gcc dot gnu.org> ---
commit r10-7160-g5c7e6d4bdf879b437b43037e10453275acabf521
Author: Segher Boessenkool <segher@kernel.crashing.org>
Date:   Thu Mar 12 07:12:50 2020 +0000

    df: Don't abuse bb->aux (PR94148, PR94042)

    The df dataflow solvers use the aux field in the basic_block struct,
    although that is reserved for any use by passes.  And not only that,
    it is required that you set all such fields to NULL before calling
    the solvers, or you quietly get wrong results.

    This changes the solvers to use a local array for last_change_age
    instead, just like it already had a local array for last_visit_age.

            PR rtl-optimization/94148
            PR rtl-optimization/94042
            * df-core.c (BB_LAST_CHANGE_AGE): Delete.
            (df_worklist_propagate_forward): New parameter last_change_age, use
            that instead of bb->aux.
            (df_worklist_propagate_backward): Ditto.
            (df_worklist_dataflow_doublequeue): Use a local array
last_change_age.