feat(ssa): Pass to preprocess functions #7072
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aakoshh
commented
Jan 15, 2025
Compilation Memory Report
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Execution Memory Report
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Compilation Report
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Execution Report
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Some observations based on the post-preprocessed SSA of
The last would benefit from a generalization of this PR but we can break out other PRs to tackle the other two cases. |
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Posting for SSA tests (obviously once cut down) SSA |
5 tasks
aakoshh
commented
Jan 16, 2025
aakoshh
changed the title
TomAFrench
reviewed
Jan 16, 2025
Changes to number of Brillig opcodes executed
🧾 Summary (10% most significant diffs)
Full diff report 👇
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Changes to Brillig bytecode sizes
🧾 Summary (10% most significant diffs)
Full diff report 👇
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Changes to circuit sizes
🧾 Summary (10% most significant diffs)
Full diff report 👇
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5 tasks
vezenovm
reviewed
Jan 17, 2025
It's because the loops are not small enough to be unrolled in Brillig #7100 (comment) |
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Found out the reason why |
![github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=60&v=4){kind=small}
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⚠️ Performance Alert ⚠️
Possible performance regression was detected for benchmark 'Compilation Time'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.10.
| Benchmark suite | Current: 04c8395 | Previous: dd70845 | Ratio |
|---|---|---|---|
ram_blowup_regression |
18.6 s |
16.1 s |
1.16 |
This comment was automatically generated by workflow using github-action-benchmark.
CC: @TomAFrench
vezenovm
reviewed
Jan 17, 2025
vezenovm
approved these changes
Jan 17, 2025
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Looks good to me! As it is Friday evening and this is a pretty meaningful PR let's hold off on merging though in case @TomAFrench wants to take another pass next week.
There was a problem hiding this comment.
⚠️ Performance Alert ⚠️
Possible performance regression was detected for benchmark 'Execution Time'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.10.
| Benchmark suite | Current: 4826682 | Previous: 7705a62 | Ratio |
|---|---|---|---|
rollup-merge |
0.008 s |
0.007 s |
1.14 |
This comment was automatically generated by workflow using github-action-benchmark.
CC: @TomAFrench
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Alright, I definitely need to make the comment trigger less sensitive... |
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Yeah, will take a look on Monday. |
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Description
Problem*
Followup for #7001 (comment)
Summary*
Adds a
Ssa::preprocess_fnspass that does a subset of SSA passes on functions in a bottom-up order, so that by the time they are inlined into other functions, they have a chance to be already simplified. The changes made are cumulative, ie. if A calls B, then B gets optimised first, and then A inlines the optimised B before it gets optimised itself.To avoid going all the way to the top and optimising the functions near the entry point, the weight of the functions (derived from their instruction count) is accumulated to the callers, and the average of the accumulated weights serves as a cutoff for running the preprocessing.
Added a
--skip-preprocess-fnsCLI option to turn this pass off.TODO:
&mutparameters #7104Additional Context
Idea
We noticed in #7001 (comment) that
maingets bloated to 65K blocks after the unrolling pass, because everything it calls has already been inlined into it, and then we have to simplify down this large function, which came with a big memory footprint.@TomAFrench suggested switching to a bottom-up scenario, where we optimise functions that get called by others before inlining them, and to start as follows:
Testing
cargo run -p nargo_cli -- --program-dir ../aztec-packages/noir-projects/noir-protocol-circuits/crates/rollup-base-public compile --silence-warnings --skip-underconstrained-check --skip-brillig-constraints-check --force --show-ssa-pass "Preprocessing"Result
Unfortunately this hasn't significantly changed the number of blocks after unrolling in the
main, at least not yet:The SSA of one of the fist
serializefunction in the linked comment changed as follows:Before Pre-processing
After Pre-processing
So this has been achieved 🎉 :
Documentation*
Check one:
PR Checklist*
cargo fmton default settings.