Re: [PATCH] forwprop: Fix up rotate pattern matching [PR106523]

[Aldy Hernandez <aldyh@redhat.com>]

On 1/17/23 10:47, Jakub Jelinek wrote:

> Aldy/Andrew, is the ranger query ok or should I use something different
> when check_range_stmt is non-NULL and I know on which statement to ask?

<snip>

> +	  int_range_max r;
> +	  if (!get_global_range_query ()->range_of_expr (r, rotcnt,
> +							 check_range_stmt))
> +	    return false;

range_of_expr will work with and without a statement.  If no statement 
is provided, it will return the global range.  So you can use the same 
range_of_expr call with a statement or without one if you don't know it.

Note that get_global_range_query () will always return a global query 
object (think SSA_NAME_RANGE_INFO).  It will never use an existing 
ranger (for example, if called within VRP or another pass that has an 
active ranger enabled).  If simplify_rotate() may be used from some of 
these passes you *may* want to use get_range_query() which will pick up 
the active ranger, or a global query object if no ranger is active.

For that matter, since get_global_range_query() uses a global query, it 
really doesn't matter if you pass a statement or not, since our global 
range store has no context (SSA_NAME_RANGE_INFO).  Although, I 
personally always pass the statement if known, because it's good form, 
and if things ever change to an active ranger, everything will just work.

Aldy