Re: [PATCH] path solver: only compute ranges at the current path position [PR126876]

On Tue, Aug 18, 2026 at 2:40 PM Aldy Hernandez <[email protected]> wrote:
>
> On Tue, Aug 18, 2026 at 12:53:20PM +0200, Richard Biener wrote:
> > On Tue, Aug 18, 2026 at 12:30 PM Aldy Hernandez <[email protected]> wrote:
>
> > Are there not in-BB side-effects to ranges that might or might not be reflected?
> >
> > I'm not sure it's sensible to use path ranger as current query.
>
> Side effects are block granular, in both rangers AFAIK, so a mid fold
> query through the path ranger either gets the global range or a cached
> value from everything seen so far in the path.  So I think we should
> be OK.
>
> However, if we're using the path ranger to ask things from the path,
> but expecting a root ranger response, that's bound to fail.  To be
> honest, we haven't stressed the path ranger outside of the backwards
> threader much (maybe loop-ch and loop unswitching??).  So the
> conservative option may be not to ask the path ranger itself, or bail
> if the cache hasn't been set up?

I think it's weird to end up with path ranger as query and we should
have fallen back to a "below" active ranger or global ranges.  I'd
have expected path ranger queries to explicitly go to it, not via
the get_range_query () active one.  Or is the gimple_ranger
instantiated by the back threader "tainted" somehow, even
when not using a path_range_query constructed from it?

Richard.

>
> I'm fine either way.
>
> Aldy