On Tue, May 28, 2024 at 8:57 PM Andrew MacLeod <amacl...@redhat.com> wrote:
>
> The original patch causing the PR made ranger's cache re-entrant to
> enable SCEV to use the current range_query when called from within ranger..
>
> SCEV uses the currently active range query (via get_range_query()) for
> picking up values. fold_using_range is the general purpose stmt folder
> many components use, and it takes a range_query to use for folding.
> When propagating values in the cache, we need to ensure no new queries
> are invoked, and when the cache is propagating and calculating outgoing
> edges, it switches to a read only range_query which uses what it knows
> about global values to come up with best result using current state.
>
> SCEV is unaware of what the caller is using for a range_query, so when
> attempting to fold a PHI node, it is re-invoking the current query
> during propagation which is undesired behavior. This patch tells
> fold_using_range to not use SCEV if the range_query being used is not
> the same as the one SCEV is going to use.
>
> Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed.
Can we dump a hint to an active dump-file if this happens? I suppose it's
an unwanted situation, like the pass not setting the active ranger? Sth
like
if (src.query () != get_range_query (cfun)
&& dump_file)
fprintf (dump_file, "Using a range query different from the
installed one\n");
(or better wording).
Btw, could we install src.query () as the global range query around the
relevant recursion or is the place around where we'd need to do this
not so clear-cut?
Richard.
> Andrew
