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

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

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

            Bug ID: 62291
           Summary: PRE uses too much memory and compile-time
           Product: gcc
           Version: 4.9.1
            Status: UNCONFIRMED
          Keywords: compile-time-hog, memory-hog
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
            Blocks: 47344

Created attachment 33409
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33409&action=edit
preprocessed testcase

For the attached testcase (from GHC) PRE blows up memory and compile-time wise
at -O2, -O2 -fno-tree-pre and -O1 are fine.

Usual suspect is AVAIL_OUT which was only eliminated for FRE.