On Mon, Nov 18, 2024 at 8:56 AM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> For pointers I forgot that BIT_IOR_EXPR is not valid so when
> I added the pattern to convert `max<a,b> != 0` (r15-5356), GCC
> would start to ICEing saying pointer types were not valid for
> BIT_IOR_EXPR.
> This fixes the problem by casting to the unsigned type of the
> inner type. There was another way of fixing this to handling it
> as `a == 0 & b == 0` but both match and reassoication (for pointers)
> will then convert it back into the form I am creating here so
> let's just use that form instead.
OK.
I'll note that at some point we discussed allowing all bit operations
on pointers,
not just BIT_AND.
Richard.
> Bootstrapped and tested on x86_64-linux-gnu.
>
> PR tree-optimization/117646
>
> gcc/ChangeLog:
>
> * match.pd (`max<a,b>==0`): Add casts to `unsigned type`.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/torture/minmaxneeqptr-1.c: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/match.pd | 6 ++++--
> .../gcc.dg/torture/minmaxneeqptr-1.c | 21 +++++++++++++++++++
> 2 files changed, 25 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/torture/minmaxneeqptr-1.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 4bec24a21b2..f5181325f3b 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -4799,9 +4799,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> MAX (A, B) != 0 -> (A|B) != 0 iff unsigned. */
> (for cmp (eq ne)
> (simplify
> - (cmp (max @0 @1) integer_zerop@2)
> + (cmp (max @0 @1) integer_zerop)
> (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
> - (cmp (bit_ior @0 @1) @2))))
> + (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
> + (cmp (bit_ior (convert:utype @0) (convert:utype @1))
> + { build_zero_cst (utype); } )))))
>
> /* Undo fancy ways of writing max/min or other ?: expressions, like
> a - ((a - b) & -(a < b)) and a - (a - b) * (a < b) into (a < b) ? b : a.
> diff --git a/gcc/testsuite/gcc.dg/torture/minmaxneeqptr-1.c
> b/gcc/testsuite/gcc.dg/torture/minmaxneeqptr-1.c
> new file mode 100644
> index 00000000000..aa45722330f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/minmaxneeqptr-1.c
> @@ -0,0 +1,21 @@
> +/* { dg-do compile } */
> +
> +/* PR tree-optimization/117646 */
> +
> +int maxeq(char *a, char *b) {
> + char *p = a < b ? b : a;
> + return p == (void*)0;
> +}
> +int maxne(char *a, char *b) {
> + char *p = a < b ? b : a;
> + return p == (void*)0;
> +}
> +
> +int mineq(char *a, char *b) {
> + char *p = a > b ? b : a;
> + return p == (void*)0;
> +}
> +int minne(char *a, char *b) {
> + char *p = a > b ? b : a;
> + return p == (void*)0;
> +}
> --
> 2.43.0
>
