[LLVMdev] Measurements of the new inlinehint attribute

Mon Feb 15 11:58:22 PST 2010

Friday I enabled the inlinehint function attribute in the inliner. It mostly affects the performance of -Os compiled code. I have made some measurements on the SPEC test suite to show what it means.

I made three runs of then nightly tests. The baseline represents -Os with no inlinehint:

make TEST=nightly OPTFLAGS=-Os EXTRA_LOPT_OPTIONS=-inlinehint-threshold=0 EXTRA_LINKTIME_OPT_FLAGS=-inlinehint-threshold=0 report

For the second run I enabled the inline hint, keeping the -Os flag:

make TEST=nightly OPTFLAGS=-Os report

The third run is -O3:

make TEST=nightly OPTFLAGS=-O3 EXTRA_LOPT_OPTIONS=-inline-threshold=275 EXTRA_LINKTIME_OPT_FLAGS=-inline-threshold=275 report

Note the when the test suite is run like this, the inliner is actually run twice. Once by opt and once by llvm-ld.

The table shows bytecode size and runtime speed (higher=faster) of the second and third runs relative to the baseline:

r96241                                      -Os    Speed      -O3     Speed
HMMER/hmmcalibrate                          0.10%   0.00%     18.18%   0.00%
Nurbs/nurbs                                 0.00%   0.00%     49.01%  -0.81%
Povray/povray                               0.01%   6.02%     39.36%  -2.53%
SPEC/CFP2000/177.mesa/177.mesa              0.00%   0.00%     14.90%  -1.12%
SPEC/CFP2000/179.art/179.art                0.00%   0.00%     19.51%   1.22%
SPEC/CFP2000/183.equake/183.equake          0.00%  -1.85%      3.54%   0.00%
SPEC/CFP2000/188.ammp/188.ammp              0.28%  -0.18%     48.68%   3.10%
SPEC/CFP2006/433.milc/433.milc              0.00%  -0.14%     20.31%   2.68%
SPEC/CFP2006/444.namd/444.namd              0.04%   0.44%      3.28%   1.40%
SPEC/CFP2006/447.dealII/447.dealII         10.61%  13.06%     35.52%  15.01%
SPEC/CFP2006/450.soplex/450.soplex          0.30%   0.00%     22.47%   0.00%
SPEC/CFP2006/470.lbm/470.lbm                0.00%   0.00%      4.91%   0.30%
SPEC/CINT2000/164.gzip/164.gzip             0.00%   0.17%     32.44%  -4.93%
SPEC/CINT2000/175.vpr/175.vpr               0.00%   1.01%     18.17%   3.34%
SPEC/CINT2000/176.gcc/176.gcc               0.31%   0.98%     32.86%   3.00%
SPEC/CINT2000/181.mcf/181.mcf               0.00%  -0.61%     11.02%  -0.15%
SPEC/CINT2000/186.crafty/186.crafty         0.00%   0.00%     23.97%   3.14%
SPEC/CINT2000/197.parser/197.parser         1.18%   1.32%     47.48%   6.23%
SPEC/CINT2000/252.eon/252.eon               2.39%   3.45%     15.34%  11.11%
SPEC/CINT2000/253.perlbmk/253.perlbmk       0.13%  -0.41%     33.45%   1.67%
SPEC/CINT2000/254.gap/254.gap               0.24%  -0.98%     13.90%   1.50%
SPEC/CINT2000/255.vortex/255.vortex         0.00%   0.00%     94.96%  -6.59%
SPEC/CINT2000/256.bzip2/256.bzip2           0.00%  -0.09%     37.42%   1.84%
SPEC/CINT2000/300.twolf/300.twolf           0.00%   0.00%      9.59%   0.96%
SPEC/CINT2006/400.perlbench/400.perlbench   0.33%   0.40%     35.88%  -2.45%
SPEC/CINT2006/401.bzip2/401.bzip2           0.00%  -0.94%     69.38%  -0.94%
SPEC/CINT2006/403.gcc/403.gcc               0.76%   0.00%     48.35%   1.20%
SPEC/CINT2006/429.mcf/429.mcf               0.00%  -1.78%     11.88%   0.61%
SPEC/CINT2006/445.gobmk/445.gobmk           0.02%   0.00%     13.86%   0.00%
SPEC/CINT2006/456.hmmer/456.hmmer           0.17%   1.72%     28.38%   1.72%
SPEC/CINT2006/458.sjeng/458.sjeng           0.19%   1.35%      8.97%   6.05%
SPEC/CINT2006/462.libquantum/462.libquantum 1.08% -20.22%    146.24%  -7.26%
SPEC/CINT2006/464.h264ref/464.h264ref       0.00%  -0.30%      9.22%   0.72%
SPEC/CINT2006/471.omnetpp/471.omnetpp       2.78%   1.92%     67.24%   3.92%
SPEC/CINT2006/473.astar/473.astar           4.59%   6.61%     12.90%  -0.87%
SPEC/CINT2006/483.xalancbmk/483.xalancbmk   4.29%   0.00%     34.72%   0.00%
SPEC/CINT95/099.go/099.go                   0.00%  -3.13%     46.93%   0.00%
SPEC/CINT95/124.m88ksim/124.m88ksim         0.06%   0.00%     11.62%  50.00%
SPEC/CINT95/126.gcc/126.gcc                 0.24%   0.00%     36.70%   0.00%
SPEC/CINT95/129.compress/129.compress       0.00%   0.00%      0.27%   0.00%
SPEC/CINT95/130.li/130.li                   0.15%   0.00%     77.44%   0.00%
SPEC/CINT95/132.ijpeg/132.ijpeg             0.00%   0.00%     11.12%   0.00%
SPEC/CINT95/134.perl/134.perl               3.55%   0.00%     33.44%   0.00%
SPEC/CINT95/147.vortex/147.vortex           0.00%   0.00%     94.80%   0.00%

Some of the tests run quite quickly, so the speed numbers should be taken with a grain of salt.

These rows have interesting changes:

SPEC/CFP2006/447.dealII/447.dealII         10.61%  13.06%     35.52%  15.01%
SPEC/CINT2000/197.parser/197.parser         1.18%   1.32%     47.48%   6.23%
SPEC/CINT2000/252.eon/252.eon               2.39%   3.45%     15.34%  11.11%
SPEC/CINT2006/456.hmmer/456.hmmer           0.17%   1.72%     28.38%   1.72%
SPEC/CINT2006/458.sjeng/458.sjeng           0.19%   1.35%      8.97%   6.05%
SPEC/CINT2006/462.libquantum/462.libquantum 1.08% -20.22%    146.24%  -7.26%
SPEC/CINT2006/471.omnetpp/471.omnetpp       2.78%   1.92%     67.24%   3.92%
SPEC/CINT2006/473.astar/473.astar           4.59%   6.61%     12.90%  -0.87%

The general picture should be that -Os performance is moved closer to -O3, but at a much smaller price in code size.

I have no idea what is wrong with 462.libquantum, and 473.astar appears to really dislike -O3 optimization.

/jakob