https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111718
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Keywords| |missed-optimization
Last reconfirmed| |2023-10-08
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> For comment #2 from EVRP:
> Folding statement: _3 = _2 / a_5(D);
> Applying pattern match.pd:934, gimple-match-4.cc:2021
> gimple_simplified to _3 = 2;
>
> Which corresponds to the match pattern:
> /* Simplify (t * 2) / 2) -> t. */
> (for div (trunc_div ceil_div floor_div round_div exact_div)
> (simplify
> (div (mult:c @0 @1) @1)
> (if (ANY_INTEGRAL_TYPE_P (type))
> (if (TYPE_OVERFLOW_UNDEFINED (type))
> @0
> #if GIMPLE
> (with {value_range vr0, vr1;}
> (if (INTEGRAL_TYPE_P (type)
> && get_range_query (cfun)->range_of_expr (vr0, @0)
> && get_range_query (cfun)->range_of_expr (vr1, @1)
> && range_op_handler (MULT_EXPR).overflow_free_p (vr0, vr1))
> @0))
> #endif
> ))))
Which was improved on the trunk by r14-4082-g55b22a6f630e (and then by
r14-4191-gd946fc1c71bd). I don't know why the original testcase is not causing
the above pattern to match though, maybe because a*2 is used twice ...
