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

[rguenth at gcc dot gnu.org via Gcc-bugs]

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

--- Comment #84 from Richard Biener <rguenth at gcc dot gnu.org> ---
So it's the usual (quadratic) culprit:

Samples: 1M of event 'cycles:u', Event count (approx.): 1675893461671           
Overhead       Samples  Command  Shared Object     Symbol                       
  20.61%        316521  f951     f951              [.] get_ref_base_and_extent
  14.42%        221221  f951     f951              [.] (anonymous
namespace)::pass_store_merging::terminate_all_aliasing_chains
   5.77%         88586  f951     f951              [.] special_function_p

I'll see whether I can do some surgery.