Re: [PATCH v4 04/12] Remove MAX_BITSIZE_MODE_ANY_INT

[Richard Biener <richard.guenther@gmail.com>]

On Tue, May 18, 2021 at 9:16 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> It is only defined for i386 and everyone uses the default:
>
>  #define MAX_BITSIZE_MODE_ANY_INT (64*BITS_PER_UNIT)
>
> Whatever problems we had before, they have been fixed now.

So I don't have a strong recollection here apart from memory usage
considerations with wide-int (possibly fixed by all the trailing-wide-int stuff
we now have).  So I'm fine if the target maintainer is - but then we probably
should remove all vestiges of non-default MAX_BITSIZE_MODE_ANY_INT,
or do we want to keep it just in case?

Thanks,
Richard.

>         * config/i386/i386-modes.def (MAX_BITSIZE_MODE_ANY_INT): Removed.
> ---
>  gcc/config/i386/i386-modes.def | 15 +++------------
>  1 file changed, 3 insertions(+), 12 deletions(-)
>
> diff --git a/gcc/config/i386/i386-modes.def b/gcc/config/i386/i386-modes.def
> index dbddfd8e48f..4e7014be034 100644
> --- a/gcc/config/i386/i386-modes.def
> +++ b/gcc/config/i386/i386-modes.def
> @@ -107,19 +107,10 @@ INT_MODE (XI, 64);
>  PARTIAL_INT_MODE (HI, 16, P2QI);
>  PARTIAL_INT_MODE (SI, 32, P2HI);
>
> -/* Mode used for signed overflow checking of TImode.  As
> -   MAX_BITSIZE_MODE_ANY_INT is only 160, wide-int.h reserves only that
> -   rounded up to multiple of HOST_BITS_PER_WIDE_INT bits in wide_int etc.,
> -   so OImode is too large.  For the overflow checking we actually need
> -   just 1 or 2 bits beyond TImode precision.  Use 160 bits to have
> -   a multiple of 32.  */
> +/* Mode used for signed overflow checking of TImode.  For the overflow
> +   checking we actually need just 1 or 2 bits beyond TImode precision.
> +   Use 160 bits to have a multiple of 32.  */
>  PARTIAL_INT_MODE (OI, 160, POI);
>
> -/* Keep the OI and XI modes from confusing the compiler into thinking
> -   that these modes could actually be used for computation.  They are
> -   only holders for vectors during data movement.  Include POImode precision
> -   though.  */
> -#define MAX_BITSIZE_MODE_ANY_INT (160)
> -
>  /* The symbol Pmode stands for one of the above machine modes (usually SImode).
>     The tm.h file specifies which one.  It is not a distinct mode.  */
> --
> 2.31.1
>