[PATCH] D31827: Add a flag that enables more aggressive load PRE

[Taewook Oh via Phabricator via llvm-commits]

twoh added a comment.

Below are the numbers with spec2006 (The numbers in the last row are overall for SPEC score and total for compile time and binary size):

-O2:

                 |                            Base                 |                      Aggressive                 |                            Diff                 |
                 |      SPEC score    compile time     binary size |      SPEC score    compile time     binary size |      SPEC score    compile time     binary size |
   400.perlbench |            27.9              30       1,207,608 |            27.6              29       1,211,704 |          -1.08%          -3.33%           0.34% |
       401.bzip2 |            18.9               4          94,400 |            19.1               3          94,400 |           1.06%         -25.00%           0.00% |
         403.gcc |            26.4              79       3,771,952 |            26.4              81       3,784,280 |           0.00%           2.53%           0.33% |
         429.mcf |            24.1               1          23,200 |            24.1               2          23,200 |           0.00%         100.00%           0.00% |
       445.gobmk |            21.8              21       3,958,128 |            21.8              21       3,962,224 |           0.00%           0.00%           0.10% |
       456.hmmer |            21.0              10         344,288 |            21.0              10         344,288 |           0.00%           0.00%           0.00% |
       458.sjeng |            22.0               4         156,192 |            22.9               4         156,192 |           4.09%           0.00%           0.00% |
  462.libquantum |            44.4               2          55,712 |            48.1               2          55,712 |           8.33%           0.00%           0.00% |
     464.h264ref |            38.5              16         694,768 |            38.7              17         694,768 |           0.52%           6.25%           0.00% |
     471.omnetpp |            17.7              30       1,553,888 |            18.4              30       1,553,888 |           3.95%           0.00%           0.00% |
       473.astar |            18.0               2         125,616 |            18.1               2         125,616 |           0.56%           0.00%           0.00% |
   483.xalancbmk |            29.5             199       6,903,592 |            29.6             203       6,907,688 |           0.34%           2.01%           0.06% |
                 |            24.8             398      18,889,344 |            25.2             404      18,913,960 |           1.61%           1.51%           0.13% |

-O3:

                 |                            Base                 |                      Aggressive                 |                            Diff                 |
                 |      SPEC score    compile time     binary size |      SPEC score    compile time     binary size |      SPEC score    compile time     binary size |
   400.perlbench |            27.2              30       3,570,840 |            27.0              35       3,581,096 |          -0.74%          16.67%           0.29% |
       401.bzip2 |            19.1               4         245,912 |            18.9               5         246,200 |          -1.05%          25.00%           0.12% |
         403.gcc |            26.0              79      10,517,504 |            26.8              93      10,546,032 |           3.08%          17.72%           0.27% |
         429.mcf |            23.7               1          62,152 |            24.2               1          62,224 |           2.11%           0.00%           0.12% |
       445.gobmk |            21.7              21       6,450,344 |            21.9              24       6,456,712 |           0.92%          14.29%           0.10% |
       456.hmmer |            21.0              10       1,034,864 |            21.1              12       1,036,112 |           0.48%          20.00%           0.12% |
       458.sjeng |            22.5               4         336,416 |            22.4               4         336,808 |          -0.44%           0.00%           0.12% |
  462.libquantum |            47.3               2         138,016 |            44.6               2         137,768 |          -5.71%           0.00%          -0.18% |
     464.h264ref |            39.0              16       1,878,656 |            39.0              21       1,884,208 |           0.00%          31.25%           0.30% |
     471.omnetpp |            19.7              30       4,468,208 |            18.9              32       4,469,464 |          -4.06%           6.67%           0.03% |
       473.astar |            18.0               2         295,152 |            18.2               3         295,824 |           1.11%          50.00%           0.23% |
   483.xalancbmk |            30.0             199      39,545,312 |            29.2             221      39,533,360 |          -2.67%          11.06%          -0.03% |
                 |            25.2             398      68,543,376 |            25.0             453      68,585,808 |          -0.79%          13.82%           0.06% |

For -O2 enabling aggressive load PRE brings somewhat expected results (better spec score, increase in compilation time and binary size). But for -O3 it doesn't even improve the spec score while increasing compile time significantly.


https://reviews.llvm.org/D31827