[PATCH][i386] Split not+broadcast+pand to broadcast+pandn.

[Andrew Pinski]

On Tue, May 25, 2021 at 6:17 PM Hongtao Liu <crazylht@gmail.com> wrote:
>
> Update patch:
>   The new patch simplify (vec_duplicate (not (nonimmedaite_operand)))
> to (not (vec_duplicate (nonimmedaite_operand))). This is not a
> straightforward simplification, just adding some tendency to pull not
> out of vec_duplicate.
>
>   For i386, it will enable below opt
>
> from
>         notl    %edi
>         vpbroadcastd    %edi, %xmm0
>         vpand   %xmm1, %xmm0, %xmm0
> to
>         vpbroadcastd    %edi, %xmm0
>         vpandn   %xmm1, %xmm0, %xmm0
>
>   Bootstrapped and regtested on x86_64-linux-gnu{-m32,}.
>   Ok for trunk?
> gcc/ChangeLog:
>
>         PR target/100711
>         * simplify-rtx.c (simplify_unary_operation_1):
>         Simplify (vec_duplicate (not (nonimmedaite_operand)))
>         to (not (vec_duplicate (nonimmedaite_operand))).
>
> gcc/testsuite/ChangeLog:
>
>         PR target/100711
>         * gcc.target/i386/avx2-pr100711.c: New test.
>         * gcc.target/i386/avx512bw-pr100711.c: New test.

This patch should not use nonimmedaite_operand at all in
simplify-rtx.c.  Rather use !CONSTANT_P (XEXP (op, 0)) instead.
And even then (not CONST_INT) will never be there anyways as it will
always be simplified to a constant in the first place.  So removing
that check is fine.

Thanks,
Andrew