[Bug tree-optimization/62291] PRE uses too much memory and compile-time

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62291

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
As said in the mail for the just applied patch:

"The second patch (once done) will refactor insertion phase
to do a dominator walk similar to what elimination does
computing AVAIL_OUT on-the-fly (and only keeping it live
for a single block).  It's a bit more complicated than
for elimination as insertion looks at a block and all its
predecessors, it's also a bit more costly as we iterate
insertion.  It's also more costly because computing
AVAIL_OUT on-the-fly requires looking at all statements
which insertion currently doesn't do at all.
So I've not yet settled on a final idea how to best re-factor it,
eventually insertion and elimination can be merged (and then
still iterate(?)).

Ideas welcome ;)"