Re: [PATCH] When simplifing BFR of an insert, require a mode precision integral type (PR108688)

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

On Wed, Feb 8, 2023 at 10:15 PM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The same problem as PR 88739 has crept in but
> this time in match.pd when simplifying bit_field_ref of
> an bit_insert. That is we are generating a BIT_FIELD_REF
> of a non-mode-precision integral type.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

Hmm.  Can we handle the case of the extraction exactly covering the
insertion separately then and simplify to plain @1?

Thanks,
Richard.

>         PR tree-optimization/108688
>
> gcc/ChangeLog:
>
>         * match.pd (bit_field_ref [bit_insert]):
>         Avoid generating BIT_FIELD_REFs of non-mode-precision
>         integral operands
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.c-torture/compile/pr108688-1.c: New test.
> ---
>  gcc/match.pd                                     |  4 +++-
>  gcc/testsuite/gcc.c-torture/compile/pr108688-1.c | 15 +++++++++++++++
>  2 files changed, 18 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr108688-1.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index c9e8bebede2..d8353072822 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -7487,7 +7487,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>        isize = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (@1)));
>    }
>    (switch
> -   (if (wi::leu_p (wi::to_wide (@ipos), wi::to_wide (@rpos))
> +   (if ((!INTEGRAL_TYPE_P (TREE_TYPE (@1))
> +         || type_has_mode_precision_p (TREE_TYPE (@1)))
> +        && wi::leu_p (wi::to_wide (@ipos), wi::to_wide (@rpos))
>         && wi::leu_p (wi::to_wide (@rpos) + wi::to_wide (@rsize),
>                       wi::to_wide (@ipos) + isize))
>      (BIT_FIELD_REF @1 @rsize { wide_int_to_tree (bitsizetype,
> diff --git a/gcc/testsuite/gcc.c-torture/compile/pr108688-1.c b/gcc/testsuite/gcc.c-torture/compile/pr108688-1.c
> new file mode 100644
> index 00000000000..43d782d62bd
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/compile/pr108688-1.c
> @@ -0,0 +1,15 @@
> +
> +
> +union U { signed int d : 7; signed int e : 2; } u;
> +int a, b;
> +
> +void
> +foo (void)
> +{
> +  for (int i = 0; i < 64; i++)
> +    {
> +      u.d = a;
> +      u.e ^= b;
> +    }
> +}
> +
> --
> 2.17.1
>