Wasmtime 45.0.0 download

45.0.0
Released 2026-05-21.
Added
- Winch now respects the enable_nan_canonicalization setting.
#12939
- Initial support for invoking component functions asynchronously has been added
to the C API.
#12973
- Cranelift's s390x backend implements more instructions from z17 and also
implements more CLIF arithmetic overflow instructions.
#12523
#12707
- Wasmtime's support for handling OOM in more APIs has expanded and is now
documented as well.
#12993
#12988
#13017
#13047
#13049
#13051
#13074
#13083
#13088
#13224
- The Component type now offers reflection APIs over the compiled in-memory
view of instructions in the same manner Module does.
#13073
- The wasmtime CLI now has a hot-blocks subcommand to explore a
perf-recorded output and show hot basic blocks of WebAssembly instructions.
#13077
- Wasmtime now has an initial implementation of a copying collector for GC,
which notably enables collecting cycles unlike the DRC collector.
#13093
#13107
- The WASI inherit_network and allow_ip_name_lookup options were added to
the C API.
#13145
- The C API now has the ability to select Winch as well as the
RegallocAlgorithm in use.
#13155
- The Wasmtime CLI now has a -Dmax-backtrace=N argument to control the number
of frames captured.
#13218
- Wasmtime now tracks whether there are any active async tasks within a store
and provides an embedder API to learn when there are none left.
#13246
- Cranelift now has an idempotent-store elimination pass.
#13251
Changed
- Wasmtime's DRC collector has received some optimizations to get some wins on
local benchmarking.
#12969
#12974
- Wasmtime's C API can now be built without the gc crate feature of Wasmtime.
#12805
- Wasmtime now has an implemented and improved grow-vs-collect heuristic to
improve behavior of GC-using programs.
#12942
- Cranelift on aarch64 now uses a more optimized frame layout for tail-call-only
functions.
#11608
- Wasmtime now supports a separate set of GC tunables different from the main
set of tunables for linear memory to enable configuring it separately.
#13080
- Wasmtime no longer uses pointer authentication instructions for the
implementation of fibers due to issues on Android.
#13118
- Wasmtime now requires Rust 1.93.0 to compile.
#13127
- The behavior of using Wasmtime as a CMake subproject has been improved.
#13157
- Reference types in the C/C++ API have been refactored and reorganized.
#13154
#13235
- The Wasmtime CLI now warns about usage of wasi-common or wasi-threads as these
components are slated for removal in Wasmtime 47.0.0. For more information see
the associated RFC.
#13264
- Inlining in Wasmtime now has a different set of configuration options, notably
more values are packed into -Cinlining=....
#13250
Fixed
- The WASIp1-to-WASIp2 adapter now handles nonblocking I/O in fd_{read,write}
more appropriately.
#13111
- The Host header is injected less often for wasmtime-wasi-http.
#13138
- Downcasts of funcref values now uses the correct type for imported
functions.
#13161
- The DRC allocator's memory usage during tracing has been reduced when there
are large arrays.
#13192
- The performance of reading stdin in WASI has been improved.
#13256
- WASI path_open(TRUNCATE) bypasses FilePerms::WRITE host restriction.
GHSA-2r75-cxrj-cmph