Perf pure go cairo0 class hash

[ongyimeng]

Summary

Replace Cairo0 class hashing with a pure-Go implementation and optimize the path.

Changes

• reimplement legacy Cairo0 hinted-hash canonicalization in Go
• remove the old Rust/FFI Cairo0 hashing path
• optimize Pedersen hashing and table initialization
• parallelize independent work in deprecated Cairo class hashing
• add stronger regression and parity tests

Results

These results are from the benchmark, BenchmarkClassV0Hash.

Runtime improved compared to the latest upstream main Rust/FFI path:

• Smaller fixture: ~7.52 ms/op -> ~6.08 ms/op, about 19.2% faster.
• Larger fixture: ~79.67 ms/op -> ~59.46 ms/op, about 25.4% faster.

Go memory metrics use the initial pure-Go baseline since Go benchmarks do not count Rust-side FFI allocations.

Go memory metrics improved compared to the initial pure-Go baseline:

• Smaller fixture:
  • ~541,656 B/op -> ~458,824 B/op, about 15.3% lower.
  • 3,025 allocs/op -> 1,881 allocs/op, about 37.8% fewer.
• Larger fixture:
  • ~3.40 MB/op -> ~2.49 MB/op, about 26.8% lower.
  • ~19.39k allocs/op -> 12,042 allocs/op, about 37.9% fewer.

Memory tradeoff:

• Pedersen 8-bit precomputed tables retain about 1 MiB.
• Rough import-time process RSS delta is about 6.1 MiB. (measured by comparing an empty process against one that imports core/crypto).

Benchmarks were run on macOS, Intel i5, with GOMAXPROCS=1

Motivation

Issue #2084

[codecov]

Codecov Report

❌ Patch coverage is 85.43544% with 97 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.21%. Comparing base (bfe781f) to head (a25522f).

Files with missing lines	Patch %	Lines
core/deprecated_cairo_program.go	84.64%	52 Missing and 26 partials ⚠️
core/crypto/pedersen_hash.go	83.50%	11 Missing and 5 partials ⚠️
core/class_hash.go	96.15%	1 Missing and 1 partial ⚠️
core/crypto/keccak.go	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3648      +/-   ##
==========================================
+ Coverage   75.96%   76.21%   +0.24%     
==========================================
  Files         395      396       +1     
  Lines       35780    36424     +644     
==========================================
+ Hits        27182    27759     +577     
- Misses       6635     6688      +53     
- Partials     1963     1977      +14     

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[RafaelGranza]

Really solid work. The test setup with starknet-rs fixtures and the snapshot are great touches.

Could you walk through the comments before merging? Most are nits or future direction ideas, no blocking items.

[RafaelGranza]

Sorry, misclicked and updated your branch with a merge instead of a rebase.
Heads up in case you want to clean it up.

[rodrodros]

All looking good so far, blocking until I get a good grasp of the code myself

[rodrodros]

@ongyimeng looks good, can you add the benchmark tests to the diff as well 🙏

[rodrodros]

Good work!