perf(fuzz): share override function lists - #16650
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Store each override target's functions in an Arc so each generated call clones a shared handle instead of every function and ABI parameter. Preserve the existing target selection, fallback, and shrinking behavior. In a profiling-build generation microbenchmark against master 2492dc0, 128-function targets fell from 13.92 us to 2.52 us per call (5.52x), and 1024-function targets fell from 92.50 us to 2.63 us (35.22x). These are component measurements, not whole-Forge speedups.
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Share each override target's function list through
Arcso generating a call clones a handle instead of every function and ABI parameter. Target selection, fallback selection, public APIs, and shrinking remain unchanged. The regression test covers target changes, unknown-target fallback, valid calldata, and shrinking; a separate comparison matched 256 seeded baseline/candidate sequences and their shrink steps. Code, tests, and benchmark analysis were produced with Codex assistance.Results
Compared with master
2492dc059using the profiling build on Apple Silicon. The syntheticfoundry-scfuzzbenchworkload has 128 handler functions, call overrides enabled, depth 64, one worker, seed0x1234, and a fresh corpus. Each revision ran one 20-second campaign. Generation timings are medians of nine alternating batches of 2,000 calls, with three ABI parameters per function.These gains are specific to synthetic call-override workloads; the one-function generation case was effectively neutral. Campaign variance across runs and projects remains unmeasured.