Re: [PATCH 2/2] Add assert for type on tree_nonzero_bits

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

On Wed, Nov 2, 2022 at 10:48 PM apinski--- via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> From: Andrew Pinski <apinski@marvell.com>
>
> Right now anyone could call tree_nonzero_bits with
> either complex or vector types and this will return
> the wrong thing. So just assert that nobody calls
> it with this.
>
> OK? Bootstrapped and tested with no regressions on x86_64-linux-gnu.

The function comment needs adjustment.  To me, nonzero bits of
a v4si would simply include all bits of v4si - isn't that what happens?
I see the SSA get_nonzero_bits uses element_precision but
tree_nonzero_bits uses TYPE_PRECISON as fallback, so I guess
the assert is correct.

Still the function comment should be amended, also ...

> gcc/ChangeLog:
>
>         * fold-const.cc (tree_nonzero_bits): Add
>         assert.
> ---
>  gcc/fold-const.cc | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
> index 7e1ea58518b..3ccac9b28df 100644
> --- a/gcc/fold-const.cc
> +++ b/gcc/fold-const.cc
> @@ -16567,6 +16567,9 @@ c_getstr (tree str)
>  wide_int
>  tree_nonzero_bits (const_tree t)
>  {
> +  gcc_assert (TREE_CODE (TREE_TYPE (t)) != VECTOR_TYPE
> +             && TREE_CODE (TREE_TYPE (t)) != COMPLEX_TYPE);

... please perform a "positive" test.  Like INTEGRAL_TYPE_P (TREE_TYPE
(t)) || POINTER_TYPE_P (TREE_TYPE (t))

Richard.

> +
>    switch (TREE_CODE (t))
>      {
>      case INTEGER_CST:
> --
> 2.17.1
>