[Bug middle-end/38474] compile time explosion in dataflow_set_preserve_mem_locs at -O3

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38474

--- Comment #103 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #102)
> At -O2 -g add_stack_var_conflict looks to be high up. Which might mean this
> introduced recently by me.

Can you split out a PR tracking this?