[Bug middle-end/29256] [4.2/4.3/4.4 regression] loop performance regression

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

------- Comment #29 from janis at gcc dot gnu dot org  2008-10-29 17:05 -------
On powerpc-linux the submitter's testcase gets better code with the patch from
comment #17, but the same testcase with the loop starting with 1 instead of
zero gets worse code.  From the 4.1 branch with -O2:

.L2:
        lfd 0,0(9)
        addi 9,9,8
        stfd 0,0(11)
        addi 11,11,8
        bdnz .L2

>From the 4.2 branch:

.L2:
        add 9,10,0
        add 11,10,8
        addi 10,10,8
        lfd 0,8(9)
        stfd 0,8(11)
        bdnz .L2

Code from current mainline is the same except for the order of the addi and lfd
instructions.


-- 

janis at gcc dot gnu dot org changed:

           What    |Removed                     |Added
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                 CC|                            |janis at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29256