Summary Continuing WebAssembly with Eect Handlers arxiv.org
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One Line
WebAssembly has control flow structuring features but lacks support for non-local control flow features such as async/await and generators/iterators.
Slides
Slide Presentation (9 slides)
Key Points
- WebAssembly (Wasm) is a low-level code format that requires source languages with non-local control flow features to transform their programs to target Wasm.
- Wasm provides features such as expressions, local variables, and blocks to structure control flow.
- Wasm 2.0 introduces reference types for first-class pointers to functions.
- Wasm can be extended with effect handlers to allow for the creation of continuations.
- The implementation of effect handlers in Wasm involves the use of suspend and resume instructions.
- Continuations are resumed by installing handlers and are discarded when evaluation terminates with values.
- Promises are represented with i32 identifiers and are interfaced with using tags like $yield and $fulfill.
- The implementation of non-local control flow in Wasm involves compiling suspend and resume instructions directly to architecture-specific instructions.
Summaries
25 word summary
WebAssembly lacks support for non-local control flow features like async/await and generators/iterators, but provides control flow structuring features such as expressions, local variables, and blocks.
34 word summary
WebAssembly (Wasm) is a low-level code format that lacks direct support for non-local control flow features like async/await and generators/iterators. Wasm provides features such as expressions, local variables, and blocks to structure control flow.
628 word summary
WebAssembly (Wasm) is a low-level code format that lacks direct support for non-local control flow features like async/await and generators/iterators. This requires source languages with these features to transform their programs to target Wasm. To address
WebAssembly (Wasm) provides features such as expressions, local variables, and blocks to structure control flow. Functions in Wasm can declare parameters, results, and locals. Wasm 2.0 introduces reference types for first-class pointers to functions
WebAssembly (Wasm) can be extended with effect handlers to allow for the creation of continuations. By declaring a tag $yield, a computation can signal that it is ready to relinquish control of execution. However, the suspend instruction only creates
The proposal is compatible with the full language and extends Wasm with function references and exceptions. The added features are highlighted in grey. Wasm provides primitive data types and reference types for functions. Instructions include constants, locals, control blocks, branches, and
The text excerpt provides an overview of the typing rules for WebAssembly code, specifically focusing on the instructions and constructs related to exception handling and continuations. It mentions the assumption of a single global module and the omission of the ability to export or import definitions
This excerpt discusses the use of eect handlers in WebAssembly (Wasm). It explains that the suspend instruction is similar to throw, but allows for resumption with different types of values. The typing rules for module-level constructs are straightforward and recursive.
Continuations are resumed by installing handlers that represent the continuation and prevent it from being resumed multiple times. Handlers are removed when evaluation terminates with values. The cont.bind function discards the old continuation and adds a new one with extended evaluation context. The resume
The function in question does not simply return a value, but instead uses it to fulfill a promise. Promises are represented with i32 identifiers, and there are four tags used to interface with promises: $yield, $fulfill, $await,
The authors discuss the implementation of WebAssembly (WasmFX) using Eect Handlers. They have implemented the full instruction set of WasmFX as an extension to the Wasm reference interpreter and have also created a prototype of WasmFX in W
The document discusses the implementation of stack switching in the bers library using x86-64 assembly code. The stack switching routine saves necessary registers to the stack and swaps the stack pointer. The translation from WasmFX continuation instructions to Wasmtime bers is
A benchmark simulating a web server workload was conducted using three different approaches: WasmFX, Asyncify, and a bespoke hand-written state machine transformation. The WasmFX and Asyncify approaches did not require programmer intervention, while the bespoke approach required
Extending WebAssembly (Wasm) with an additional type system to ensure that continuations are only invoked once would be burdensome, so instead, a dynamic check is used to trap any attempts to invoke a continuation multiple times. Wasm currently lacks
The document discusses the implementation of eect handlers in WebAssembly (Wasm), specifically focusing on the resume-with and suspend-to instructions. It explores the tradeos between named and unnamed handlers, highlighting the benefits of named handlers for eect encapsulation.
The document discusses the design and implementation of non-local control flow in WebAssembly (Wasm) using effect handlers. The authors propose compiling suspend and resume instructions directly to architecture-specific instructions to reduce overhead. They suggest passing values directly instead of storing and loading
This summary provides a concise version of the text excerpt while preserving important details and highlighting key points. The summary is organized into separate paragraphs to distinguish distinct ideas for readability, while retaining the original order in which ideas were presented.
The text excerpt includes references to
WebAssembly (Release 1.0) and the Function Reference Types Proposal for WebAssembly have been accessed in 2019 and 2022, respectively. The upcoming release of WebAssembly (Release 2.0) is expected in 202