v0.28.0 - 2023-03-01

Added

• Added support for the tail-call Wasm proposal. (#683)
• Added support for Linker defined host functions. (#692)
  • Apparently this PR introduced some performance wins for the Wasm target according to our tests.
    This information shall be taken with a grain of salt since we are not sure why those performance
    improvement occured since the PR's functionality is orthogonal to Wasm engine performance.
  • Required precursor refactoring PR: #681

Changed

• The wasmi_wasi crate now more closely mirrors the wasmtime_wasi crate API. (#700)

Internal

• Refactor the wasmi Wasm engine to handle Wasm calls and returns in its core. (#694)
  • This improved performance of Wasm function calls significantly at the cost of host function call performance.
  • Also this seemed to have impacts Wasm target performance quite positively, too.
• The Store now handles Wasm functions and host functions separately. (#686)
  • This allows to store Wasm functions into the StoreInner type which was an important
    step towards the major refactoring in (#694)
  • It was expected that host function call performance would degrade by this PR but our tests
    actually showed that the opposite was true and Wasm target performance was improved overall.
• Introduce ValueStackPtr abstraction for the wasmi engine core. (#688)
  • This change significantly improved performance especially on the Wasm target according to our tests.
• Optimize memory.{load,store} when reading or writing single bytes. (#689)
  • The performance wins were more modest than we hoped but still measurable.
• Use StoreContextMut<T> instead of impl AsContextMut in the wasmi engine core. (#685)
  • This is a simple refactoring with the goal to make the Rust compiler have a simpler job at
    optimizing certain functions in the engine's inner workings since StoreContextMut provides
    more information to the compiler.