On Fri, May 11, 2018 at 1:53 PM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On Fri, May 4, 2018 at 6:23 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
>> Hi,
>> Following Jeff's suggestion, I am now using existing tree-ssa-live.c and
>> tree-ssa-coalesce.c to compute register pressure, rather than inventing
>> another live range solver.
>>
>> The major change is to record region's basic blocks in var_map and use that
>> information in computation, rather than FOR_EACH_BB_FN.  For now only loop
>> and function type regions are supported.  The default one is function type
>> region which is used in out-of-ssa.  Loop type region will be used in next
>> patch to compute information for a loop.
>>
>> Bootstrap and test on x86_64 and AArch64 ongoing.  Any comments?
>
> I believe your changes to create_outofssa_var_map should be done differently
> by simply only calling it from the coalescing context and passing in the
> var_map rather than initializing it therein and returning it.
>
> This also means the coalesce_vars_p flag in the var_map structure looks
> somewhat out-of-place.  That is, it looks you could do with many less
> changes if you refactored what calls what slightly?  For example
> the extra arg to gimple_can_coalesce_p looks unneeded.
>
> Just as a note I do have a CFG helper pending that computes RPO order
> for SEME regions (attached).  loops are SEME regions, so your RTYPE_SESE
> is somewhat odd - I guess RTYPE_LOOP exists only because of the
> convenience of passing in a loop * to the "constructor".  I'd rather
> drop this region_type thing and always assume a SEME region - at least
> I didn't see anything in the patch that depends on any of the forms
> apart from the initial BB gathering.

Hi Richard,

Thanks for reviewing.  I refactored tree-ssa-live.c and
tree-ssa-coalesce.c following your comments.
Basically I did following changes:
1) Remove region_type and only support loop region live range computation.
    Also I added one boolean field in var_map indicating whether we
are computing
    loop region live range or out-of-ssa.
2) Refactored create_outofssa_var_map into create_coalesce_list_for_region and
    populate_coalesce_list_for_outofssa.  Actually the original
function name doesn't
    quite make sense because it has nothing to do with var_map.
3) Hoist init_var_map up in call stack.  Now it's called by caller
(out-of-ssa or live range)
    and the returned var_map is passed to coalesce_* stuff.
4) Move global functions to tree-outof-ssa.c and make them static.
5) Save/restore flag_tree_coalesce_vars in order to avoid updating
checks on the flag.

So how is this one?  Patch attached.

Thanks,
bin
2018-05-15  Bin Cheng  <bin.cheng@arm.com>

    * tree-outof-ssa.c (tree-ssa.h, tree-dfa.h): Include header files.
    (create_default_def, for_all_parms): Moved from tree-ssa-coalesce.c.
    (parm_default_def_partition_arg): Ditto.
    (set_parm_default_def_partition): Ditto.
    (get_parm_default_def_partitions): Ditto and make it static.
    (get_undefined_value_partitions): Ditto and make it static.
    (remove_ssa_form): Refactor call to init_var_map here.
    * tree-ssa-coalesce.c (build_ssa_conflict_graph): Support live range
    computation for loop region.
    (coalesce_partitions, compute_optimized_partition_bases): Ditto.
    (register_default_def): Delete.
    (for_all_parms, create_default_def): Move to tree-outof-ssa.c.
    (parm_default_def_partition_arg): Ditto.
    (set_parm_default_def_partition): Ditto.
    (get_parm_default_def_partitions): Ditto and make it static.
    (get_undefined_value_partitions): Ditto and make it static.
    (coalesce_with_default, coalesce_with_default): Update comment.
    (create_coalesce_list_for_region): New func factored out from
    create_outofssa_var_map.
    (populate_coalesce_list_for_outofssa): New func factored out from
    create_outofssa_var_map and coalesce_ssa_name.
    (create_outofssa_var_map): Delete.
    (coalesce_ssa_name): Refactor to support live range computation.
    * tree-ssa-coalesce.h (coalesce_ssa_name): Change decl.
    (get_parm_default_def_partitions): Delete.
    (get_undefined_value_partitions): Ditto.
    * tree-ssa-live.c (init_var_map, delete_var_map): Support live range
    computation for loop region.
    (new_tree_live_info, loe_visit_block): Ditto.
    (live_worklist, set_var_live_on_entry): Ditto.
    (calculate_live_on_exit, verify_live_on_entry): Ditto.
    * tree-ssa-live.h (struct _var_map): New fields.
    (init_var_map): Change decl.
    (region_contains_p): New.