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ADP-011 — Structural Performance & Ergonomics Roadmap

• Status: Approved
• Date: 2026-09-26
• Deciders: Poppy Team
• Phase: Post-v0.1.0 Planning / Architectural Evolution

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Context & Diagnosis

During phase P04 and early P05, seven local micro-optimization experiments failed to produce reproducible speedups and were accordingly rolled back.

An architectural audit proved that the Aipo bytecode interpreter operates with a structural floor of ~100ns per opcode (~300 CPU cycles). Local micro-optimizations cannot penetrate this floor. Comparative measurements against Wren 0.4.0 and Luau 0.739 revealed systemic gaps in arithmetic loops and dynamic method dispatch overhead.

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Architectural Performance Decisions

1. Value Compaction to 16/24 Bytes:

   • Reduce the size of Value from 48 bytes down to 16-24 bytes, slashing memory bandwidth pressure by up to 66% and quadrupling value density per L1 cache line.

2. Method Invocation Fusion (InvokeMethod):

   • Compile direct calls expr.method(args...) into the fused opcode InvokeMethod (rather than separate GetField + Call), eliminating ~200,000 ephemeral BoundMethod allocations in iterative workloads.

3. Dispatch Loop with Hoisted Variables:

   • Refactor the VM inner loop with critical execution state pinned in local CPU registers (ip, stack_base, code).

4. Superinstructions & Specialization:

   • Specialized opcode variants such as Call0..Call4 and GetLocal0..GetLocal3 eliminating extra immediate decoding overhead.

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Language Ergonomics Decisions

1. Structured Faults (Model B+): Allow fail to accept any value or struct instance as its fault payload with strongly-typed inspection in recover.
2. Pattern Matching & Destructuring: Introduce match expr with structural and collection destructuring.
3. Static Type Narrowing: Flow-sensitive type inference in aipo-sema to elide redundant dynamic runtime type checks.