updated costs_5

[rob-stacks]

Description

This patch assigns the new runtime costs based on the clarity-cost-bench tool (valgrind based) available at https://github.com/rob-stacks/stacks-core/tree/feat/costs_bench_valgrind.

This is the (current) results/analysis of the tool

costs.txt

Every entry has a detailed comment explaining the logic behind the math/values

Additional Notes

• Few of the functions are still not covered
• The tool is able to measure MARF accesses too, as a secondart step we could revisit the read/write costs too (even if they rarely caused issues)
• The clarity contract for costs should be updated too but for making to PR more readable i am deferring it to a different PR

Applicable issues

Additional info (benefits, drawbacks, caveats)

Checklist

• Test coverage for new or modified code paths
• For new Clarity features or consensus changes, add property tests (see docs/property-testing.md)
• Changelog fragment(s) or "no changelog" label added (see changelog.d/README.md)
• Required documentation changes (e.g., rpc/openapi.yaml for RPC endpoints, event-dispatcher.md for new events)
• New clarity functions have corresponding PR in clarity-benchmarking repo

[coveralls]

Coverage Report for CI Build 29114246895

Warning

Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes.
Quick fix: rebase this PR. Learn more →

Warning

No base build found for commit 8a3bd08 on release/4.0.0.
Coverage changes can't be calculated without a base build.
If a base build is processing, this comment will update automatically when it completes.

Coverage: 86.537%

Details

• Patch coverage: 59 uncovered changes across 1 file (98 of 157 lines covered, 62.42%).

Uncovered Changes

File	Changed	Covered	%
clarity/src/vm/costs/costs_5.rs	150	91	60.67%
Total (3 files)	157	98	62.42%

Coverage Regressions

Requires a base build to compare against. How to fix this →

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Coverage Stats

Relevant Lines:	231363
Covered Lines:	200214
Line Coverage:	86.54%
Coverage Strength:	19343271.96 hits per line

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💛 - Coveralls

[cylewitruk-stacks]

It feels a bit like we should have https://github.com/rob-stacks/stacks-core/tree/feat/costs_bench_valgrind PR'd/reviewed/merged before merging in costs based on it? Or, what does everyone else think?

[aaronb-stacks]

It feels a bit like we should have https://github.com/rob-stacks/stacks-core/tree/feat/costs_bench_valgrind PR'd/reviewed/merged before merging in costs based on it? Or, what does everyone else think?

I'm not too worried about merging that branch before the costs -- historically, the benchmarks lived in a separate repo entirely, and the cost changes were reviewed more or less exactly this way. Not that this is the best process in the world, but I'm not convinced that we should hold up review of the PR to change that.

[Copilot]

Pull request overview

This PR updates the Clarity 6 / Epoch 4.0 runtime cost schedule (costs_5.rs) by replacing many Costs4 forwards with new bench-derived formulas (plus associated snapshot/changelog updates), based on Callgrind instruction-count measurements from clarity-cost-bench.

Changes:

• Recalibrates many Costs5 runtime cost functions with new constants/linear formulas derived from benchmarking.
• Updates an existing chainstate test snapshot to reflect the new runtime cost outputs.
• Adds a changelog fragment documenting the new calibration and a crypto-cost correction.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
clarity/src/vm/costs/costs_5.rs	Replaces many forwarded costs with new bench-derived runtime formulas/constants for Epoch 4.0.
stackslib/src/chainstate/tests/snapshots/blockstack_lib__chainstate__tests__static_analysis_tests__tuple_merge_overflow_unused_runtime_ccall.snap	Updates expected runtime cost values to match the recalibrated schedule.
changelog.d/costs-5-valgrind-calibration.changed	Documents the calibration methodology/baseline and notable cost changes.

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[rob-stacks]

Updated the tool to correctly profile index-of and comparison functions. Set the baseline to 80k per unit (a bit more conservative). Re-uploaded costs.txt with the new values

The base branch was changed.

[aaronb-stacks]

Changed base branch to develop, now that pox-wf-integration has been merged there, we're preparing the 4.0 release from there.

[cylewitruk-stacks]

Throwing another Copilot sanity-check at it quick

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

The base branch was changed.

[brice-stacks]

this looks good, but can we also remove costs-5.clar here (along with its deployment), so that don't end up with a cost contract that doesn't match the actual costs?