I have noticed that PackCC generates calls to pcc_value_table__resize and pcc_value_table__resize even when there are no captures or values respectively.
I'd expect this to have no measurable impact, as the first instruction in the function is actually checking if the resize is needed. But benchmarking shows, that it is actually measurable and that avoiding the function calls results in consistent speed improvement of couple percent:
$ RUN_REPEATS=200 benchmark/benchmark.sh origin/master optimize-table-resizing
...
Run performance:
================
origin/master optimize-table-resizing
calc 132 ms (100%) 258 MB (100%) 132 ms (99%) 250 MB (96%)
json 33 ms (100%) 101 MB (100%) 33 ms (98%) 101 MB (99%)
kotlin 245 ms (100%) 410 MB (100%) 234 ms (95%) 409 MB (99%)
I have tested it with gcc 13 and clang 16, both with -O2.
arithy
commented
1 year ago
I have noticed that PackCC generates calls to
pcc_value_table__resizeandpcc_value_table__resizeeven when there are no captures or values respectively.I'd expect this to have no measurable impact, as the first instruction in the function is actually checking if the resize is needed. But benchmarking shows, that it is actually measurable and that avoiding the function calls results in consistent speed improvement of couple percent:
I have tested it with gcc 13 and clang 16, both with -O2.