On Mon, 13 Oct 2025, Avinash Jayakar wrote:
> Hi,
>
> As stated in patch for PR104116, 2 issues were found for unsigned division by
> power of 2. The {ROUND,CEIL}_DIV_EXPR should not use the canonicalization
> pattern, since their semantics are different.
> The tests in patch for PR104116 already cover this scenario which currently
> fail, therefore I have not added any tests in this patch.
>
> Bootstrapped and regtested on ppc64le and x86_64. Ok for master?
OK for trunk and affected branches.
Thanks,
Richard.
> Thanks and regards,
> Avinash Jayakar
>
> Canonicalization of unsigned division by power of 2 only applies to
> {TRUNC,FLOOR,EXACT}_DIV, therefore remove the same pattern for
> {CEIL,ROUND}_DIV, which was added in a previous commit.
>
> 2025-10-13 Avinash Jayakar <[email protected]>
>
> gcc/ChangeLog:
> PR tree-optimization/122213
> * match.pd: Canonicalize unsigned pow2 div only for trunk, floor and
> exact div.
>
> ---
> gcc/match.pd | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 4d0a803eaef..41ec9da8aaa 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -981,16 +981,18 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) && TYPE_UNSIGNED (TREE_TYPE (@0)))
> (bit_and @0 (negate @1))))
>
> -(for div (trunc_div ceil_div floor_div round_div exact_div)
> +/* Canonicalize unsigned t / 4 to t >> 2. */
> #if GIMPLE
> - /* Canonicalize unsigned t / 4 to t >> 2. */
> +(for div (trunc_div floor_div exact_div)
> (simplify
> (div @0 integer_pow2p@1)
> (if (INTEGRAL_TYPE_P (type)
> && (TYPE_UNSIGNED (type) || tree_expr_nonnegative_p (@0)))
> (rshift @0 { build_int_cst (integer_type_node,
> - wi::exact_log2 (wi::to_wide (@1))); })))
> + wi::exact_log2 (wi::to_wide (@1))); }))))
> #endif
> +
> +(for div (trunc_div ceil_div floor_div round_div exact_div)
> /* Simplify (t * u) / u -> t. */
> (simplify
> (div (mult:c @0 @1) @1)
>
--
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
