[Bug tree-optimization/90316] [8/9 Regression] large compile time increase in opt / alias stmt walking for Go example

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90316

--- Comment #30 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 46347
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46347&action=edit
incremental patch

Unfortunately the 46339 attachment failed during bootstrap compare.  The
attached
one incrementally changes the iteration scheme from dominator-based to
RPO-based
which should strictly interate less.

If that provides a reasonable speedup on its own it would be also a candidate
for backporting.