[lra] pseudo assignment improvements

[Vladimir Makarov <vmakarov at redhat dot com>]

For this month I tried many different heuristics of spilling and 
assignment in LRA (about 10 of them, including spilling for inheritance 
reloads).  Here is the best what I found.  The major idea is to assign 
and spill for pseudos which are ordered by threads (set of reload 
pseudos connected by inheritance pseudos).

The patch mostly implements the new idea for assigning and spilling for 
reload pseudos.  The patch also fixes a typo introduced in the previous 
patch which actually prohibited undo-inheritance subpass and resulted in 
worse code.  The patch also fixes an insignificant valgrind error 
(reading uninitialized data).

The patch was successfully bootstrapped on x86/x86-64 and ppc64.

2011-09-29  Vladimir Makarov <vmakarov@redhat.com>

        * lra-int.h (lra_get_copy): New prototype.

        * lra.c (lra_get_copy): New function.

        * lra-saves.c (lra_save_restore): Ignore scratches.

        * lra-constraints.c (remove_inheritance_pseudos): Fix a typo in
        checking remove_pseudos emptiness.

        * lra-assign.c (reload_insn_num): Remove.
        (struct regno_assign_info): New.
        (regno_assign_info): New array.
        (process_copy_to_form_allocno, init_regno_assign_info): New.
        (finish_regno_assign_info): New.
        (reload_pseudo_compare_func): Rewrite using threads.
        (find_hard_regno_for): Check value for conflicting reload pseudos.
        (spill_for): Use reload_pseudo_compare_func instead of
        pseudo_compare_func.
        (assign_by_spills): Print info about processed reload and
        inheritance pseudos.
        (lra_assign): Call init_regno_assign_info and
        finish_regno_assign_info.

Attachment: assignment-improvement.patch
Description: Text document