[Patch] IRA: Update heuristics for optimal coalescing

[Ajit Kumar Agarwal]

Hello Vladimir:

The changes in the patch are made in the frequency heuristics for optimal 
coalescing. The Loop back edge frequencies are taken instead 
of the block frequency for optimal coalescing. Ignores the frequency for the 
loop for the allocno not having references inside the loops
but spans the loops and live at the exit block of the loop. Another similar 
change are made not to consider allcono frequency at the cost 
calculation but to consider the loop back edge frequencies having references 
and spans through the loop and live at the exit of the block.

We have tested the changes with MIBench and EEMBC benchmarks and there is a 
gain in the Geomean for the overall benchmarks for
Microblaze target. Also no regressions are seen in deja GNU tests run for 
microblaze.

Please let us know with your feedbacks.

commit e6a2edd3794080a973695f80e77df3e7de55452d
Author: Ajit Kumar Agarwal <ajitkum@xhdspdgnu.(none)>
Date:   Fri Feb 27 11:15:48 2015 +0530

    IRA: Update heuristics for optimal coalescing.
    
    The changes are made in the frequency heuristics for optimal coalescing.
    The Loop back edge frequencies are taken instead of the block frequency
    for optimal coalescing. Ignores the frequency for the loop having not any
    references but spans the loop and live at the exit block of the loop.
    Another similar change not to consider allcono frequency at the cost
    calculation but to consider the loop back edge frequencies having references
    and spans through the loop and live at the exit of the block.
    
    ChangeLog:
    2015-02-27  Ajit Agarwal  <ajit...@xilinx.com>
    
        * ira-color.c (ira_loop_back_edge_freq): New.
        (coalesce_allocnos): Use of ira_loop_back_edge_freq to update
        the back edge frequencies.
        (setup_coalesced_allocno_costs_and_nums): Use of
        ira_loop_back_edge_freq to update the cost.
    
    Signed-off-by:Ajit Agarwal ajit...@xilinx.com

Thanks & Regards
Ajit

0001-IRA-Update-heuristics-for-optimal-coalescing.patch
Description: 0001-IRA-Update-heuristics-for-optimal-coalescing.patch