[Bug lto/83804] New: [meta] LTO memory consumption

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83804

            Bug ID: 83804
           Summary: [meta] LTO memory consumption
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: hubicka at ucw dot cz, jamborm at gcc dot gnu.org,
                    marxin at gcc dot gnu.org, rguenth at gcc dot gnu.org
  Target Milestone: ---

I'm creating this PR to track a bit memory consumption of LTO. As Richi merged
early debug changes in time of GCC stage1, let use the PR to track memory
footprint.

I'm going to attach numbers for current head of GCC-7 branch and current trunk.
Both are with --enable-gather-detailed-mem-stats, so memory usage is bit higher
due to all scaffolding needed for -fmem-report.