From the pystats doc (pystats-2023-02-05-python-5a2b984.md), I find that LOAD_CONST + RETURN_VALUE is a very high frequency (Because the default return of the function is None).
Successors for LOAD_CONST
| Successors | Count | Percentage |
|---|
| RETURN_VALUE | 969,173,651 | 21.8% |
| BINARY_OP_ADD_INT | 418,647,997 | 9.4% |
| LOAD_CONST | 403,185,774 | 9.1% |
| COMPARE_AND_BRANCH_INT | 314,633,792 | 7.1% |
| STORE_FAST | 295,563,626 | 6.6% |
And predecessors for RETURN_VALUE
| Predecessors | Count | Percentage |
|---|
| LOAD_CONST | 969,173,651 | 29.9% |
| LOAD_FAST | 505,933,343 | 15.6% |
| RETURN_VALUE | 382,698,373 | 11.8% |
| BUILD_TUPLE | 328,532,240 | 10.1% |
| COMPARE_OP | 107,210,803 | 3.3% |
This means that if we add a RETURN_CONST, we can reduce the RETURN_VALUE instruction by 30% and the LOAD_CONST instruction by 20%.
./bin/python3 -m pyperf timeit -w 3 --compare-to ../python-3.12/bin/python3 -s "
def test():
return 10000
" "test()"
/python-3.12/bin/python3: ..................... 27.0 ns +- 0.3 ns
/cpython/bin/python3: ..................... 25.0 ns +- 0.5 ns
Mean +- std dev: [/python-3.12/bin/python3] 27.0 ns +- 0.3 ns -> [/cpython/bin/python3] 25.0 ns +- 0.5 ns: 1.08x faster
./bin/python3 -m pyperf timeit -w 3 --compare-to ../python-3.12/bin/python3 -s "
def test():
return None
" "test()"
/python-3.12/bin/python3: ..................... 27.2 ns +- 1.3 ns
/cpython/bin/python3: ..................... 25.1 ns +- 0.6 ns
Mean +- std dev: [/python-3.12/bin/python3] 27.2 ns +- 1.3 ns -> [/cpython/bin/python3] 25.1 ns +- 0.6 ns: 1.08x faster
From the microbenchmark that there is indeed a ~10% improvement (considering the interference of function calls, I think 10% should be there), which is not very high, but it should be an optimization without adverse effects.
Linked PRs
From the pystats doc (pystats-2023-02-05-python-5a2b984.md), I find that
LOAD_CONST + RETURN_VALUEis a very high frequency (Because the default return of the function is None).Successors for LOAD_CONST
And predecessors for RETURN_VALUE
This means that if we add a
RETURN_CONST, we can reduce theRETURN_VALUEinstruction by 30% and theLOAD_CONSTinstruction by 20%.From the microbenchmark that there is indeed a ~10% improvement (considering the interference of function calls, I think 10% should be there), which is not very high, but it should be an optimization without adverse effects.
Linked PRs