[Bug rtl-optimization/88275] New: Memory hog in selective scheduler

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88275

            Bug ID: 88275
           Summary: Memory hog in selective scheduler
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: memory-hog
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---
            Target: powerpc-*-linux-gnu, powerpcspe-*-linux-gnu

gcc-9.0.0-alpha20181125 snapshot (r266441) exhibits high memory consumption
compiling gcc/testsuite/gcc.c-torture/compile/20001226-1.c w/ -O2
-fselective-scheduling -fno-code-hoisting -fno-sched-interblock
-fno-tree-dominator-opts -fno-tree-fre -fno-tree-pre.

 scheduling                         : 135.46 ( 93%)   3.52 ( 87%) 277.00 ( 93%)
1597632 kB ( 90%)

perf top:

  27.72%  cc1           [.] concat_INSN_LIST
  23.20%  cc1           [.] free_INSN_LIST_list
  13.51%  cc1           [.] alloc_INSN_LIST
  11.78%  cc1           [.] deps_join
  10.76%  cc1           [.] ggc_internal_alloc
   3.19%  cc1           [.] free_deps
   2.35%  libc-2.27.so  [.] memset
   2.31%  cc1           [.] gen_rtx_INSN_LIST
   1.84%  cc1           [.] rtx_alloc_stat_v
   0.70%  cc1           [.] rtx_alloc
   0.40%  cc1           [.] sd_find_dep_between_no_cache
   0.37%  cc1           [.] memset@plt
   0.22%  cc1           [.] sched_rgn_compute_dependencies
   0.18%  cc1           [.] sd_next_list
   0.15%  libc-2.27.so  [.] __libc_calloc
   0.11%  cc1           [.] check_dep
   0.11%  cc1           [.] bitmap_ior_into

The testcase takes much less memory when compiling for other targets or when
not using selective scheduling for the first scheduling pass.