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[PATCH, x86] Use vector moves in memmove expanding

This patch adds a new algorithm of expanding movmem in x86 and a bit
refactor existing implementation. This is a reincarnation of the patch
that was sent wasn't checked couple of years ago - now I reworked it
from scratch and divide into several more manageable parts.

For now this algorithm isn't used, because cost_models are tuned to
use existing ones. I believe the new algorithm will give better
performance, but I'll leave cost-models tuning for a separate patch.

Also, I changed get_mem_align_offset to make it handle MEM_REFs as
well. Probably, there is another way of getting info about alignment -
if so, please let me know.

Similar improvements could be done in expanding of memset, but that's
in progress now and I'm going to proceed with it if this patch is ok.

Bootstrap/make check/Specs2k are passing on i686 and x86_64.

Is it ok for trunk?

Changelog entry:

2013-04-10  Michael Zolotukhin  <>

        * config/i386/i386-opts.h (enum stringop_alg): Add vector_loop.
        * config/i386/i386.c (expand_set_or_movmem_via_loop): Use
        adjust_address instead of change_address to keep info about alignment.
        (emit_strmov): Remove.
        (emit_memmov): New function.
        (expand_movmem_epilogue): Refactor to properly handle bigger sizes.
        (expand_movmem_epilogue): Likewise and return updated rtx for
        (expand_constant_movmem_prologue): Likewise and return updated rtx for
        destination and source.
        (decide_alignment): Refactor, handle vector_loop.
        (ix86_expand_movmem): Likewise.
        (ix86_expand_setmem): Likewise.
        * config/i386/i386.opt (Enum): Add vector_loop to option stringop_alg.
        * emit-rtl.c (get_mem_align_offset): Compute alignment for MEM_REF.

Best regards,
Michael V. Zolotukhin,
Software Engineer
Intel Corporation.

Attachment: memmov.patch
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