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[Bug rtl-optimization/60317] New: [4.9 Regression] find_hard_regno_for compile time hog in libvpx


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60317

            Bug ID: 60317
           Summary: [4.9 Regression] find_hard_regno_for compile time hog
                    in libvpx
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
                CC: vmakarov at gcc dot gnu.org

While building Firefox I've noticed that there is a file from libvpx
that takes almost 2 minutes to compile on my machine:

 % time gcc -O3 -c sad_c.i
gcc -O3 -c sad_c.i  111.05s user 0.78s system 99% cpu 1:52.10 total

 phase opt and generate  : 110.92 (100%) usr   0.43 (100%) sys 111.43 (100%)
wall  168173 kB (99%) ggc

Perf shows:
 87.86%  cc1  cc1   [.] find_hard_regno_for(int, int*, int)
   - find_hard_regno_for(int, int*, int)
        99.77% 0x10101010101
  0.72%  cc1  cc1   [.] find_base_term(rtx_def*)


It's fine with -O2 or 4.8.3:

 % time gcc -O2 -c sad_c.i
gcc -O2 -c sad_c.i  0.25s user 0.02s system 99% cpu 0.273 total

 phase opt and generate  :   0.23 (96%) usr   0.02 (100%) sys   0.25 (93%) wall
   8876 kB (84%) ggc

 % time /usr/x86_64-pc-linux-gnu/gcc-bin/4.8.3/gcc -w -O3 -c sad_c.i
/usr/x86_64-pc-linux-gnu/gcc-bin/4.8.3/gcc -w -O3 -c sad_c.i  0.94s user 0.02s
system 99% cpu 0.964 total


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