[Bug middle-end/39326] Segmentation fault with -O1, out of memory with -O2

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39326

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |steven at gcc dot gnu.org

--- Comment #24 from Steven Bosscher <steven at gcc dot gnu.org> 2013-03-06 23:39:27 UTC ---
(In reply to comment #22)
> 4.8.0  -O2  (terminated after 9 minutes waiting, LIM being the offender, I
> suspect domwalk ...)  >2.5GB
> 
> applying domwalk fix ...

It is LIM, for sure. I've been watching in GDB for a while at some
back traces, and it's spent minutes already in this DOM walk:

#5  0x0000000000b841e1 in walk_dominator_tree (walk_data=0x7fffffffdd60,
bb=0x7fffef033958) at ../../trunk/gcc/domwalk.c:187
#6  0x0000000000c02d73 in determine_invariantness () at
../../trunk/gcc/tree-ssa-loop-im.c:1189
#7  tree_ssa_lim () at ../../trunk/gcc/tree-ssa-loop-im.c:2632
#8  0x000000000075bcd7 in execute_one_pass (pass=0x12323e0 <pass_lim>) at
../../trunk/gcc/passes.c:2330
#9  0x000000000075c0f5 in execute_pass_list (pass=0x12323e0 <pass_lim>) at
../../trunk/gcc/passes.c:2378

This is supposed to be cheap. Is this a known bottle-neck?

Pathetic...