Reduce amount of branching and work duplication in generate_moves. #3300
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We could also take this as a better way to write the same |
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@Sopel97 to be honest, I don't know. I don't know what is important and what isn't when it comes to compiler optimization. And results shows no difference. We should focus on readability (and being sincere, I don't like mine very much). Great job, anyway. |
joergoster
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Jan 14, 2021
This change simplifies control flow in the generate_moves function which ensures the compiler doesn't duplicate work due to possibly not resolving pureness of the function calls. Also the biggest change is the removal of the unnecessary condition checking for empty b in a convoluted way. The rationale for removal of this condition is that computing attacks_bb with occupancy is not much more costly than computing pseudo attacks and overall the condition (also being likely unpredictable) is a pessimisation. This is inspired by previous changes by @BM123499. Passed STC: LLR: 2.94 (-2.94,2.94) {-0.25,1.25} Total: 88040 W: 8172 L: 7931 D: 71937 Ptnml(0-2): 285, 6128, 30957, 6361, 289 https://tests.stockfishchess.org/tests/view/5ffc28386019e097de3ef1c7 closes official-stockfish/Stockfish#3300 No functional change.
BM123499
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Feb 22, 2021
This change simplifies control flow in the generate_moves function which ensures the compiler doesn't duplicate work due to possibly not resolving pureness of the function calls. Also the biggest change is the removal of the unnecessary condition checking for empty b in a convoluted way. The rationale for removal of this condition is that computing attacks_bb with occupancy is not much more costly than computing pseudo attacks and overall the condition (also being likely unpredictable) is a pessimisation. This is inspired by previous changes by @BM123499. Passed STC: LLR: 2.94 (-2.94,2.94) {-0.25,1.25} Total: 88040 W: 8172 L: 7931 D: 71937 Ptnml(0-2): 285, 6128, 30957, 6361, 289 https://tests.stockfishchess.org/tests/view/5ffc28386019e097de3ef1c7 closes official-stockfish#3300 No functional change.
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This is inspired by previous changes by @BM123499.
This change simplifies control flow in the
generate_movesfunction which ensures the compiler doesn't duplicate work due to possibly not resolving pureness of the function calls. Also the biggest change is the removal of the unnecessary condition checking for emptybin a convoluted way. The rationale for removal of this condition is that computing attacks_bb with occupancy is not much more costly than computing pseudo attacks and overall the condition (also being likely unpredictable) is a pessimisation.Passed STC:
https://tests.stockfishchess.org/tests/view/5ffc28386019e097de3ef1c7
The test was performed against BM's branch that was merged into master. the only change for this PR is that I added
[[maybe_unused]]as making sure the variable is not defined in some cases is not trivial.