perf: delegate G2 MSM to generic XYZZ Pippenger#86
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Replace the hand-written G2 Pippenger (Jacobian buckets, per-window parallelism) with a thin wrapper that delegates to the generic MSM(F, Fp2).computeWithPool(). This gives G2 the same optimizations as G1: XYZZ bucket coordinates (7M+2S vs 7M+4S per mixed add), batch window normalization via Montgomery's trick, and chunk-based parallelism for better cache locality. G2Point and AffinePoint(Fp2) share identical memory layout, so the bridging is a zero-cost @ptrCast with comptime layout assertions. 339 → 118 lines, public API (msmG2, msmG2Bench) unchanged. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The generic MSM's parallel path previously fell back to sequential Pippenger when n < num_threads*256 (chunks too small). This caused a regression for G2 MSM at sizes 256-2048, where the old hand-written code used per-window parallelism. Add pippengerMSMWindowParallel: each thread processes a subset of windows over all points, using XYZZ buckets + batch normalization. Used when n < num_threads*256; chunk-based parallelism still used for larger inputs where cache locality matters more. Benefits both G1 and G2. G2 parallel MSM at N=1024: 6.9ms → 4.4ms. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
MSM(F, Fp2).computeWithPool()(~80 lines of new code)@ptrCastwith comptime layout assertions —G2PointandAffinePoint(Fp2)have identical memory layoutmsmG2,msmG2Bench) unchanged — no caller modifications neededTest plan
zig build test— all unit tests pass, including the arkworks-validated G2 MSM fixture vectorscargo run --release -p zolt -- prove examples/sha256_2048.elftiming comparison🤖 Generated with Claude Code