[Bug tree-optimization/18507] New: block_defs_stack varrray should not be GC'ed

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

For the testcase in PR 13776 (ir.ii) we spend a lot of time (10% out of 120 seconds) in ggc_alloc.
Most of that time comes from creatting/expanding the block_defs_stack varray in tree-into-ssa.c
Why is this GC allocated in the first place?
Maybe this should be a non-gc'ed VEC.
We know that this varray does not spill out from rewrite_blocks/rewrite_ssa_into_ssa at all.

-- 
           Summary: block_defs_stack varrray should not be GC'ed
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: minor
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18507