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Wasm3 calls its interpreter design a "meta machine": https://github.com/wasm3/wasm3/blob/main/docs/Interpreter.md#m3-massey-meta-machine https://github.com/wasm

Wasm3 calls its interpreter design a "meta machine": https://github.com/wasm3/wasm3/blob/main/docs/Interpreter.md#m3-massey-meta-machine https://github.com/wasm3/wasm3/blob/main/docs/Interpreter.md... It is heavily based around tail calls. I recently wrote a blog article about how we applied a similar tail-call-oriented strategy to accelerate protobuf parsing to 2+GB/s: https://blog.reverberate.org/2021/04/21/musttail-efficient-interpreters.html https://blog.reverberate.org/2021/04/21/musttail-efficient-i... I also recently landed a change in Clang trunk that offers guaranteed tail calls, so that this tail call design is safe in non-opt builds: https://reviews.llvm.org/D99517 https://reviews.llvm.org/D99517 I think wasm3 could benefit from using this attribute when it is available.

glandium 6y ago
How do guaranteed tail calls work when you needs to put arguments on the stack, which usually prevents tail call? (and whether a specific call needs to pass arguments on the stack depends on the platform, and the number and type of arguments)
- haberman 6y ago
  The musttail attribute performs several checks to ensure that a tail call can be guaranteed, and rejects the program if these rules are violated. The documentation has the details: https://github.com/llvm/llvm-project/blob/3b8ec86fd576b9808dc63da620d9a4f7bbe04372/clang/include/clang/Basic/AttrDocs.td#L449-L468 https://github.com/llvm/llvm-project/blob/3b8ec86fd576b9808d... These rules guarantee that the tail call is possible to perform on every platform. They end up being more strict than is necessary on some platforms and calling conventions.