On Tue, Oct 10, 2023 at 4:23 AM HAO CHEN GUI <guihaoc@linux.ibm.com> wrote:

> Hi David,
>
>   Thanks for your review comments.
>
> 在 2023/10/9 23:42, David Edelsohn 写道:
> >      #define MOVE_MAX (! TARGET_POWERPC64 ? 4 : 8)
> >      #define MAX_MOVE_MAX 8
> >     +#define MOVE_MAX_PIECES (!TARGET_POWERPC64 ? 4 : 16)
> >     +#define COMPARE_MAX_PIECES (!TARGET_POWERPC64 ? 4 : 16)
> >
> >
> > How are the definitions of MOVE_MAX_PIECES and COMPARE_MAX_PIECES
> determined?  The email does not provide any explanation for the
> implementation.  The rest of the patch is related to vector support, but
> vector support is not dependent on TARGET_POWERPC64.
>
> By default, MOVE_MAX_PIECES and COMPARE_MAX_PIECES is set the same value
> as MOVE_MAX. The move and compare instructions are required in
> compare_by_pieces, those macros are set to 16 byte when supporting
> vector mode (V16QImode). The problem is rs6000 hasn't supported TImode
> for "-m32". We discussed it in issue 1307. TImode will be used for
> move when MOVE_MAX_PIECES is set to 16. But TImode isn't supported
> with "-m32" which might cause ICE.
>
> So MOVE_MAX_PIECES and COMPARE_MAX_PIECES is set to 4 for 32 bit
> target in this patch. They could be changed to 16 after rs6000
> supports TImode with "-m32".
>

Hi, Hao

Thanks for the explanation.

Are you stating that although PPC32 supports V16QImode in VSX, the
move_by_pieces support also requires TImode, which is not available on
PPC32?

Thanks, David