Cadence Compiler - phase 2 (WIP)

[j1010001]

Cadence compiler project end-goal (Long-term):

Build Cadence compiler and VM to enable execution of Cadence code as efficiently as possible (as close to the native machine code of the used execution node architecture as practical), to achieve the maximum transaction throughput on the execution node.

Phase 2 goal:

Complete Cadence compiler & VM using custom bytecode. This is middle-ground between current execution using Cadence Interpreter and the end-goal with compilation + VM to native machine code.
Replace the Cadence interpreter with concurrent on-chain compilation of contracts + transactions and their execution by custom-bytecode VM. The custom bytecode is designed to achieve this goal with minimal complexity, mapping as closely as possible to the existing Cadence language functionality/operations, which makes it possible to partially reuse existing interpreter code in the custom VM.

Phase 2 goal Outcomes:

• Build the foundation for the next phase - gradual targeted compiler + VM optimizations to move the execution stack to lower-level / native code.
• Custom bytecode provides new abstraction layer in the execution stack, which improves our ability to add new features into the language without braking promise of backwards-compatible runtime.
• Reduce the execution stack complexity
  • Metering can be performed at the bytecode level, which is much easier than the current approach with instrumentation of interpreter functionality which is much larger surface to cover.
• We are not expecting significant performance improvement in this phase, the goal is to achieve correctness parity & comparable performance with the existing Cadence interpreter.

Phase 2 timeline:

Q1 2025 - brake down and estimate remaining Cadence interpreter operations to be implemented, discuss & plan the integration of concurrent compilation & VM into the execution node stack. Provide estimation of remaining effort for compiler phase 2 before the end of Q1 2025. Start implementation.

Main Tasks (WIP)

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1. Complete list of operations that we already support and those that we need to add to the compiler/VM. #3721
   +0
2. Add diagram of compilation “pipeline” to internal docs #3722
   +0
3. Make existing interpreter values reusable in VM #3693
   Improvement Technical Debt +2
   
4. Compare RISC-V/Swift to Custom ISA/Go #3697
   Performance Research +2
   

   
5. Add tracing to interpreter #3696
   +0
   
6. Standardize internal error messages #3688
   Feedback Improvement +2
   
7. Add some benchmark programs #3702
   Research +1
   

Stretch-goals

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1. Avoid conversion from StaticType to sema.Type during runtime sub-type checking #3691
   Improvement Performance +2

Notes
Based on internal notes: https://www.notion.so/flowfoundation/Compilation-Discussion-1441aee1232480c897aed36c8f763e30

Phase 1 outcomes (completed):

• Better understanding of what target(s) to consider - Ruled out Move VM and WebAssembly.