bytes: document null termination - #4
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A process-lifetime static has a stuck refcount (RC_STUCK == INT32_MIN), on which dup and drop are semantically no-ops. But both are negative, so kk_block_dup/kk_block_drop sent them down the `rc <= 0` path into the out-of-line kk_block_check_dup/kk_block_check_drop -- every dup and every drop of a static cost a real call to do nothing. Those two helpers were #2 and #4 by self time (7.0% and 4.2%) in a profile of interface parsing. Test the sticky range inline before the call. Ordinary blocks pay nothing: with rc > 0 neither branch is taken, so the new test is only ever reached on the already-slow path. The hot static is the EMPTY EVIDENCE VECTOR: @open-none0/1/2 wraps every effect operation in `evv-swap-create0(); ..; evv-set(w)`, dupping and dropping that static twice per operation. The fix is general though -- every nullary constructor and shared singleton pays the same toll. Measured: C microbench, dup+drop of a static 3.4ns -> 1.6ns C microbench, dup+drop of a normal block 2.5ns -> 2.5ns (unchanged) tail-resumptive effect operation 13.7ns -> 10.2ns (-26%) parsing 209 interfaces 56.2s -> 50.2s (-10.7%) 425 examples 0 failures; koka-community port sweep 423/17/2/0 and multimodule gate green. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Pieced together from what I learnt in koka-community/uv#4 (comment)