[Bug tree-optimization/46590] long compile time with -O2 and many loops

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46590

--- Comment #40 from Richard Biener <rguenth at gcc dot gnu.org> ---
On the full testcase tree LIM uses too much memory (I didn't merge some of
the patches that only benefit this kind of testcase ... bah).  Without LIM
we use around 1GB of memory at -O2 and

 df reaching defs        :  19.42 (14%) usr  35.49 (82%) sys  55.13 (30%) wall 
     0 kB ( 0%) ggc
 alias stmt walking      :  34.25 (25%) usr   0.47 ( 1%) sys  34.76 (19%) wall 
  1451 kB ( 0%) ggc
 tree CFG cleanup        :   7.75 ( 6%) usr   0.04 ( 0%) sys   7.73 ( 4%) wall 
  5002 kB ( 1%) ggc
 tree PTA                :  22.32 (16%) usr   0.10 ( 0%) sys  22.43 (12%) wall 
  7882 kB ( 1%) ggc
 TOTAL                 : 137.59            43.38           180.98            
866898 kB

-O3 is similar.

I have a patch for the memory usage issue.