Wasmtime Files

34.0.0

Released 2025-06-20.

Added

• Support for SIMD in the Pulley interpreter can now be disabled at compile-time to shrink the size of the final binary. #10727

• The C API now has wasmtime_trap_new_code to create a wasm_trap_t from its code. #10765

• Winch's support for x86_64 is now classified with tier 1 support in Wasmtime. #10755

• Winch's support for aarch64 now implements stack checks to pass many more spec tests. #10763

• Cranelift's s390x backend now has full support for the f128 type. #10774

• Wasmtime's C API for the component model has initial support for calling functions. #10697 #10841 #10858 #10864 #10877

• The wasmtime wast command now has a --generate-dwarf flag to show filename/line number information for backtraces. #10780

Changed

• The shape of bindgen!-generated add_to_linker functions has changed with the removal of GetHost and replacement of a HasData trait. For more information see the associated PR. #10770

• Wasmtime's Store<T> now requires that T: 'static. This is done in preparation for merging WASIp3 work to the main repository with some more information on the associated PR. #10760

• The wasmtime::component::Instance::instance_pre method is now public. #10761

• Wasmtime and Cranelift's minimnum supported version of Rust (MSRV) is now 1.85.0. #10785

• Cranelift's debugtrap on aarch64 now generates brk #0xf000 for debuggers to recognize it. #10813

• The wasi-http implementation no longer generates a trap if the handle to receive the response on the host is dropped early. #10833

• The wasmtime serve command will now send some boilerplate descriptive HTML on a 500 server error instead of nothing. #10851

• A significant amount of work has gone into the new assembler for the x64 backend. Too many PRs to list here but progress continues apace at defining all machine instructions in a standalone crate.

• Cranelift will now reject unimplemented big-endian loads/stores on backends that do not implement this functionality. #10863

• The wasmtime explore generated HTML handles large modules better now. #10892

• Wasmtime's internal representation of wasmtime::Func has changed and a previous optimization of Func::call has been lost. If affected it'd recommended to use Func::call_unchecked instead or to open an issue. #10897