wasmtime/RELEASES.md

Wasmtime Releases

---

0.36.0

Unreleased.

Added

• Support for epoch-based interruption has been added to the C API. #3925

Removed

• Support for Config::interruptable and InterruptHandle has been removed from the wasmtime crate. Users should migrate to using epoch-based interruption instead. #3925

---

0.35.1

Released 2022-03-09.

Fixed

• Fixed a bug in the x86-64 lowering of the uextend opcode for narrow (i8, i16) integer sources when the value is produced by one of several arithmetic instructions. #3906

0.35.0

Released 2022-03-07.

Added

• The wasmtime_wasi::add_to_linker function now allows providing a context object of a custom type instead of wasmtime_wasi::WasiCtx, as long as that type implements the required WASI snapshot traits. This allows, for example, wrapping WasiCtx into a struct and providing custom implementations for those traits to override the default behaviour.

Changed

• WebAssembly tables of funcref values are now lazily initialized which can, in some cases, greatly speed up instantiation of a module. #3733

• The memfd feature in 0.34.0, now renamed to memory-init-cow, has been enabled by default. This means that, where applicable, WebAssembly linear memories are now initialized with copy-on-write mappings. Support from this has been expanded from Linux-only to include macOS and other Unix systems when modules are loaded from precompiled *.cwasm files on disk. #3777 #3778 #3787 #3819 #3831

• Clarify that SSE 4.2 (and prior) is required for running WebAssembly code with simd support enabled on x86_64. #3816 #3817 #3833 #3825

• Support for profiling with VTune is now enabled at compile time by default, but it remains disabled at runtime by default. #3821

• The ModuleLimits type has been removed from the configuration of the pooling allocator in favor of configuring the total size of an instance allocation rather than each individual field. #3837

• The native stack size allowed for WebAssembly has been decreased from 1 MiB to 512 KiB on all platforms to better accomodate running wasm on the main thread on Windows. #3861

• The wasi-common crate now supports doing polls for both read and write interest on a file descriptor at the same time. #3866

Fixed

• The Store::call_hook callback is now invoked when entering host functions defined with *_unchecked variants. #3881

Removed

• The incomplete and unmaintained ARM32 backend has been removed from Cranelift. #3799

---

0.34.1

Released 2022-02-16.

Security Fixes

• CVE-2022-23636: Fixed an invalid drop of a partially-initialized instance in the pooling instance allocator.

0.33.1

Released 2022-02-16.

Security Fixes

• CVE-2022-23636: Fixed an invalid drop of a partially-initialized instance in the pooling instance allocator.

0.34.0

Released 2022-02-07.

Fixed

• The wasi-common default implementation of some attributes of files has been updated to ensure that wasi-libc's isatty function works as intended. #3696

• A benign debug assertion related to externref and garbage-collection has been fixed. #3734

Added

• Function names are now automatically demangled when informing profilers of regions of JIT code to apply Rust-specific demangling rules if applicable. #3683

• Support for profiling JIT-generated trampolines with VTune has been added. #3687

• Wasmtime now supports a new method of async preemption dubbed "epoch-based interruption" which is intended to be much more efficient than the current fuel-based method of preemption. #3699

• On Linux Wasmtime will now by default use copy-on-write mappings to initialize memories of wasm modules where possible, accelerating instantiation by avoiding costly memory copies. When combined with the pooling allocator this can also be used to speed up instance-reuse cases due to fewer syscalls to change memory mappings being necessary. #3697 #3738 #3760

• Wasmtime now supports the recently-added sock_accept WASI function. #3711

• Cranelift now has support for specifying blocks as cold. #3698

Changed

• Many more instructions for the x64 backend have been migrated to ISLE, additionally with refactorings to make incorrect lowerings harder to accidentally write. #3653 #3659 #3681 #3686 #3688 #3690 #3752

• More instructions in the aarch64 backend are now lowered with ISLE. #3658 #3662

• The s390x backend's lowering rules are now almost entirely defined with ISLE. #3702 #3703 #3706 #3717 #3723 #3724

• Instantiation of modules in Wasmtime has been further optimized now that the copy-on-write memory initialization removed the previously most-expensive part of instantiating a module. #3727 #3739 #3741 #3742

---

0.33.0

Released 2022-01-05.

Added

• Compiled wasm modules may now optionally omit debugging information about mapping addresses to source locations, resulting in smaller binaries. #3598

• The WebAssembly SIMD proposal is now enabled by default. #3601

---

0.32.1

Released 2022-01-04.

Fixed

• Cranelift: remove recently-added build dependency on sha2 to allow usage in some dependency-sensitive environments, by computing ISLE manifest hashes with a different hash function. #3619

• Cranelift: fixed 8- and 16-bit behavior of popcount (bit population count) instruction. Does not affect Wasm frontend. #3617

• Cranelift: fixed miscompilation of 8- and 16-bit bit-rotate instructions. Does not affect Wasm frontend. #3610

---

0.32.0

Released 2021-12-13.

Added

• A new configuration option has been added to force using a "static" memory style to automatically limit growth of memories in some configurations. #3503

• The InstancePre<T> type now implements Clone. #3510

• Cranelift's instruction selection process has begun to be migrated towards the ISLE compiler and definition language. #3506

• A pooling-allocator feature has been added, which is on-by-default, to disable the pooling allocator at compile time. #3514

Fixed

• A possible panic when parsing a WebAssembly name section has been fixed. #3509

• Generating native DWARF information for some C-produced modules has been fixed, notably those where there may be DWARF about dead code. #3498

• A number of SIMD code generation bugs have been fixed in the x64 backend by migrating their lowerings to ISLE.

---

0.31.0

Released 2021-10-29.

Added

• New Func::new_unchecked and Func::call_unchecked APIs have been added with accompanying functions in the C API to improve the performance of calls into wasm and the host in the C API. #3350

• Release binaries are now available for the s390x-unknown-linux-gnu architecture. #3372

• A new ResourceLimiterAsync trait is added which allows asynchronous blocking of WebAssembly on instructions such as memory.grow. #3393

Changed

• The Func::call method now takes a slice to write the results into rather than returning a boxed slice. #3319

• Trampolines are now covered when jitdump profiling is enabled. #3344

Fixed

• Debugging with GDB has been fixed on Windows. #3373

• Some quadradic behavior in Wasmtime's compilation of modules has been fixed. #3469 #3466

• Bounds-checks for wasm memory accesses in certain non-default configurations have been fixed to correctly allow loads at the end of the address space. #3462

• When type-checking memories and tables for satisfying instance imports the runtime size of the table/memory is now consulted instead of the object's original type. #3450

Removed

• The Lightbeam backend has been removed, as per RFC 14. #3390

• Cranelift's old x86 backend has been removed, as per RFC 12. #3309

0.30.0

Released 2021-09-17.

Security Fixes

• CVE-2021-39216: Fixed a use after free passing externrefs to Wasm in Wasmtime.

• CVE-2021-39218: Fixed an out-of-bounds read/write and invalid free with externrefs and GC safepoints in Wasmtime.

• CVE-2021-39219: Fixed a bug where using two different Engines with the same Linker-define functions caused unsafety without unsafe blocks.

Added

• Added experimental support for the in-progress 64-bit memories Wasm proposal.

• Added support to build Wasmtime without the compiler. This lets you run pre-compiled Wasm modules, without the ability (or potential attack surface) of compiling new Wasm modules. The compilation functionality is gated by the on-by-default cranelift cargo feature.

• Added support for NaN canonicalization with SIMD vectors.

• Added support for differential fuzzing against V8's Wasm engine.

• Added support for fuzzing against the Wasm spec interpreter.

• Enabled SIMD fuzzing on oss-fuzz.

Changed

• A variety of performance improvements to loading pre-compiled modules.

• A variety of performance improvements to function calls, both through Rust and the C API.

• Leaf functions that do not use the stack no longer bump the frame pointer on aarch64 and s390x.

• Many updates and expanded instruction support to the in-progress CLIF interpreter.

• Expanded fuzzing of reference types and GC.

Fixed

• A number of fixes to both aarch64 and x86_64 support for the Wasm SIMD proposal and the underlying CLIF vector instructions.

• Fixed a potential infinite loop in the SSA computation for cranelift-frontend. This was not reachable from cranelift-wasm or Wasmtime, but might have affected general Cranelift users.

Removed

• The wasmtime wasm2obj subcommand has been removed. Generating raw object files for linking natively is no longer supported. Use the wasmtime compile subcommand to pre-compile a Wasm module and wasmtime run to run pre-compiled Wasm modules.

0.29.0

Released 2021-08-02.

Changed

• Instance exports are now loaded lazily from instances instead of eagerly as they were before. This is an internal-only change and is not a breaking change. #2984

• All linear memories created by Wasmtime will now, by default, have guard pages in front of them in addition to after them. This is intended to help mitigate future bugs in Cranelift, should they arise. #2977

• Linear memories now correctly support a maximum size of 4GB. Previously, the limit field was 32 bits, which did not properly support a full 4GB memory. This update is also a necessary change in preparation for future memory64 support. #3013 #3134

• Injection counts of fuel into a wasmtime::Store now uses a u64 instead of a u32. #3048

Added

• Support for i128 has improved in the AArch64 backend. #2959 #2975 #2985 #2990 #3002 #3004 #3005 #3008 #3027

• The s390x backend now supports z14 and atomics. #2988 #2991

• The wasmtime::Linker type now implements Clone. #2993

• Support for the SIMD proposal on both x86_64 and AArch64 has improved. On x86_64, all SIMD opcodes are now supported. #2997 #3035 #2982 #3084 #3082 #3107 #3105 #3114 #3070 #3126

• A Trap can now display its reason without also displaying the backtrace. #3033

• An initiall fuzzer for CLIF has been added. #3038

• High-level architecture documentation has been added for Wasmtime. #3019

• Support for multi-memory can now be configured in Wasmtime's C API. #3071

• The wasmtime crate now supports a posix-signals-on-macos feature to force the usage of signals instead of mach ports to handle traps on macOS. #3063

• Wasmtime's C API now has a wasmtime_trap_code function to get the raw trap code, if present, for a trap. #3086

• Wasmtime's C API now has a wasmtime_linker_define_func function to define a store-independent function within a linker. #3122

• A wasmtime::Linker::module_async function was added as the asynchronous counterpart to wasmtime::Linker::module. #3121

Fixed

• Compiling the wasmtime crate into a dylib crate type has been fixed. #3010

• The enter/exit hooks for WebAssembly are now executed for an instance's start function, if present. #3001

• Some WASI functions in wasi-common have been fixed for big-endian platforms. #3016

• Wasmtime no longer erroneously assumes that all custom sections may contain DWARF information, reducing instances of Trap's Display implementation providing misleading information to set an env var to get more information. #3083

• Some issues with parsing DWARF debug information have been fixed. #3116

0.28.0

Released 2021-06-09.

Changed

• Breaking: Wasmtime's embedding API has been redesigned, as specified in RFC 11. Rust users can now enjoy easier times with Send and Sync, and all users can now more clearly manage memory, especially in the C API. Language embeddings have been updated to the new API as well. #2897

Added

• A new InstancePre type, created with Linker::instantiate_pre, has been added to perform type-checking of an instance once and reduce the work done for each instantiation of a module: #2962

• Deserialization of a module can now optionally skip checking the wasmtime version string: #2945

• A method has been exposed to frontload per-thread initialization costs if the latency of every last wasm call is important: #2946

• Hooks have been added for entry/exit into wasm code to allow embeddings to track time and other properties about execution in a wasm environment: #2952

• A C++ embedding of Wasmtime has been written.

Fixed

• Multiple returns on macOS AArch64 have been fixed: #2956

0.27.0

Released 2021-05-21.

Security Fixes

• Fixed a security issue in Cranelift's x64 backend that could result in a heap sandbox escape due to an incorrect sign-extension: #2913.

Added

• Support for IBM z/Archiecture (s390x) machines in Cranelift and Wasmtime: #2836, #2837, #2838, #2843, #2854, #2870, #2871, #2872, #2874.

• Improved async support in wasi-common runtime: #2832.

• Added Store::with_limits, StoreLimits, and ResourceLimiter to the Wasmtime API to help with enforcing resource limits at runtime. The ResourceLimiter trait can be implemented by custom resource limiters to decide if linear memories or tables can be grown.

• Added allow-unknown-exports option for the run command: #2879.

• Added API to notify that a Store has moved to a new thread: #2822.

• Documented guidance around using Wasmtime in multithreaded contexts: #2812. In the future, the Wasmtime API will change to allow some of its core types to be Send/Sync; see the in-progress #2897 for details.

• Support calls from native code to multiple-return-value functions: #2806.

Changed

• Breaking: Memory::new has been changed to return Result as creating a host memory object is now a fallible operation when the initial size of the memory exceeds the store limits.

Fixed

• Many instruction selection improvements on x64 and aarch64: #2819, #2828, #2823, #2862, #2886, #2889, #2905.

• Improved performance of Wasmtime runtime substantially: #2811, #2818, #2821, #2847, #2900.

• Fixed WASI issue with file metadata on Windows: #2884.

• Fixed an issue with debug info and an underflowing (trapping) offset: #2866.

• Fixed an issue with unwind information in the old x86 backend: #2845.

• Fixed i32 spilling in x64 backend: #2840.

0.26.0

Released 2021-04-05.

Added

• Added the wasmtime compile command to support AOT compilation of Wasm modules. This adds the Engine::precompile_module method. Also added the Config::target method to change the compilation target of the configuration. This can be used in conjunction with Engine::precompile_module to target a different host triple than the current one. #2791

• Support for macOS on aarch64 (Apple M1 Silicon), including Apple-specific calling convention details and unwinding/exception handling using Mach ports. #2742, #2723

• A number of SIMD instruction implementations in the new x86-64 backend. #2771

• Added the Config::cranelift_flag_enable method to enable setting Cranelift boolean flags or presets in a config.

• Added CLI option --cranelift-enable to enable boolean settings and ISA presets.

• Deduplicate function signatures in Wasm modules. #2772

• Optimize overheads of calling into Wasm functions. #2757, #2759

• Improvements related to Module Linking: compile fewer trampolines;

  #2774

• Re-export sibling crates from wasmtime-wasi to make embedding easier without needing to match crate versions. #2776

Changed

• Switched the default compiler backend on x86-64 to Cranelift's new backend. This should not have any user-visible effects other than possibly runtime performance improvements. The old backend is still available with the old-x86-backend feature flag to the cranelift-codegen or wasmtime crates, or programmatically with BackendVariant::Legacy. We plan to maintain the old backend for at least one more release and ensure it works on CI. #2718

• Breaking: Module::deserialize has been removed in favor of Module::new.

• Breaking: Config::cranelift_clear_cpu_flags was removed. Use Config::target to clear the CPU flags for the host's target.

• Breaking: Config::cranelift_other_flag was renamed to Config::cranelift_flag_set.

• CLI changes:

  • Wasmtime CLI options to enable WebAssembly features have been replaced with a singular --wasm-features option. The previous options are still supported, but are not displayed in help text.
  • Breaking: the CLI option --cranelift-flags was changed to --cranelift-set.
  • Breaking: the CLI option --enable-reference-types=false has been changed to --wasm-features=-reference-types.
  • Breaking: the CLI option --enable-multi-value=false has been changed to --wasm-features=-multi-value.
  • Breaking: the CLI option --enable-bulk-memory=false has been changed to --wasm-features=-bulk-memory.

• Improved error-reporting in wiggle. #2760

• Make WASI sleeping fallible (some systems do not support sleep). #2756

• WASI: Support poll_oneoff with a sleep. #2753

• Allow a StackMapSink to be passed when defining functions with cranelift-module. #2739

• Some refactoring in new x86-64 backend to prepare for VEX/EVEX (e.g., AVX-512) instruction encodings to be supported. #2799

Fixed

• Fixed a corner case in srem (signed remainder) in the new x86-64 backend: INT_MIN % -1 should return 0, rather than trapping. This only occurred when avoid_div_traps == false was set by the embedding. #2763

• Fixed a memory leak of the Store when an instance traps. #2803

• Some fuzzing-related fixes. #2788, #2770

• Fixed memory-initialization bug in uffd allocator that could copy into the wrong destination under certain conditions. Does not affect the default wasmtime instance allocator. #2801

• Fix printing of float values from the Wasmtime CLI. #2797

• Remove the ability for the Linker to instantiate modules with duplicate import strings of different types. #2789

0.25.0

Released 2021-03-16.

Added

• An implementation of a pooling instance allocator, optionally backed by userfaultfd on Linux, was added to improve the performance of embeddings that instantiate a large number of instances continuously. #2518

• Host functions can now be defined on Config to share the function across all Store objects connected to an Engine. This can improve the time it takes to instantiate instances in a short-lived Store. #2625

• The Store object now supports having typed values attached to it which can be retrieved from host functions. #2625

• The wiggle code generator now supports async host functions. #2701

Changed

• The Func::getN{,_async} APIs have all been removed in favor of a new Func::typed API which should be more compact in terms of API surface area as well as more flexible in how it can be used. #2719

• Engine::new has been changed from returning Engine to returning anyhow::Result<Engine>. Callers of Engine::new will need to be updated to use the ? operator on the return value or otherwise unwrap the result to get the Engine.

Fixed

• Interpretation of timestamps in poll_oneoff for WASI have been fixed to correctly use nanoseconds instead of microseconds. #2717

0.24.0

Released 2021-03-04.

Added

• Implement support for async functions in Wasmtime #2434

Fixed

• Fix preservation of the sigaltstack on macOS #2676
• Fix incorrect semver dependencies involving fs-set-times. #2705
• Fix some i128 shift-related bugs in x64 backend. #2682
• Fix incomplete trap metadata due to multiple traps at one address #2685

0.23.0

Released 2021-02-16.

Added

• Support for limiting WebAssembly execution with fuel was added, including support in the C API. #2611 #2643
• Wasmtime now has more knobs for limiting memory and table allocations #2617
• Added a method to share Config across machines #2608
• Added a safe memory read/write API #2528
• Added support for the experimental wasi-crypto APIs #2597
• Added an instance limit to Config #2593
• Implemented module-linking's outer module aliases #2590
• Cranelift now supports 128-bit operations for the new x64 backend. #2539
• Cranelift now has detailed debug-info (DWARF) support in new backends (initially x64). #2565
• Cranelift now uses the POPCNT, TZCNT, and LZCNT, as well as SSE 4.1 rounding instructions on x64 when available.
• Cranelift now uses the CNT, instruction on aarch64 when available.

Changed

• A new WASI implementation built on the new cap-std crate was added, replacing the previous implementation. This brings improved robustness, portability, and performance.

• wasmtime_wasi::WasiCtxBuilder moved to wasi_cap_std_sync::WasiCtxBuilder.

• The WebAssembly C API is updated, with a few minor API changes #2579

Fixed

• Fixed a panic in WASI fd_readdir on large directories #2620
• Fixed a memory leak with command modules #2017

---

0.22.0

Released 2021-01-07.

Added

• Experimental support for the module-linking proposal was added. #2094

• Added support for the reference types proposal on the aarch64 architecture. #2410

• Experimental support for wasi-nn was added. #2208

Changed

Fixed

• Fixed an issue where the select instruction didn't accept v128 SIMD operands. #2391

• Fixed an issue where Wasmtime could potentially use the wrong stack map during GCs, leading to a panic. #2396

• Fixed an issue where if a host-defined function erroneously returned a value from a different store, that value would be leaked. #2424

• Fixed a bug where in certain cases if a module's instantiation failed, it could leave trampolines in the store that referenced the no-longer-valid instance. These trampolines could be reused in future instantiations, leading to use after free bugs. #2408

• Fixed a miscompilation on aarch64 where certain instructions would read SP instead of the zero register. This could only affect you if you explicitly enabled the Wasm SIMD proposal. #2548

---

0.21.0

Released 2020-11-05.

Added

• Experimental support for the multi-memory proposal was added. #2263

• The Trap::trap_code API enables learning what kind of trap was raised. #2309

Changed

• WebAssembly module validation is now parallelized. #2059

• Documentation is now available at docs.wasmtime.dev. #2317

• Windows now compiles like other platforms with a huge guard page instead of having its own custom limit which made modules compile and run more slowly. #2326

• The size of the cache entry for serialized modules has been greatly reduced. #2321 #2322 #2324 #2325

• The FuncType API constructor and accessors are now iterator-based. #2365

Fixed

• A panic in compiling reference-types-using modules has been fixed. #2350

---

0.20.0

Released 2020-09-23.

Added

• Support for explicitly serializing and deserializing compiled wasm modules has been added. #2020

• A wasmtime_store_gc C API was added to run GC for externref. #2052

• Support for atomics in Cranelift has been added. Support is not fully implemented in Wasmtime at this time, however. #2077

• The Caller::get_export function is now implemented for Func references as well. #2108

Fixed

• Leaks in the C API have been fixed. #2040

• The wasm_val_copy C API has been fixed for reference types. #2041

• Fix a panic with Func::new and reference types when the store doesn't have reference types enabled. #2039

---

0.19.0

Released 2020-07-14.

Added

• The WebAssembly reference-types proposal is now supported in Wasmtime and the C API. #1832, #1882, #1894, #1901, #1923, #1969, #1973, #1982, #1984, #1991, #1996

• The [WebAssembly simd proposal's][simd] spec tests now pass in Wasmtime. #1765, #1876, #1941, #1957, #1990, #1994

• Wasmtime can now be compiled without the usage of threads for parallel compilation, although this is still enabled by default. #1903

• The C API is now documented. #1928, #1959, #1968

• A wasmtime_linker_get_one_by_name function was added to the C API. #1897

• A wasmtime_trap_exit_status function was added to the C API. #1912

• Compilation for the aarch64-linux-android target should now work, although keep in mind this platform is not fully tested still. #2002

Fixed

• Runtime warnings when using Wasmtime on musl have been fixed. #1914

• A bug affecting Windows unwind information with functions that have spilled floating point registers has been fixed. #1983

Changed

• Wasmtime's default branch and development now happens on the main branch instead of master. #1924

Removed

• The "host info" support in the C API has been removed since it was never fully or correctly implemented. #1922

• Support for the *_same functions in the C API has been removed in the same vein as the host info APIs. #1926

---

0.18.0

Release 2020-06-09.

Added

The WasmTy trait is now implemented for u32 and u64.

#1808

---

0.17.0

Released 2020-06-01.

Added

• The Commands and Reactors ABI is now supported in the Rust API. Linker::module loads a module and automatically handles Commands and Reactors semantics.

  #1565

The Table::grow function now returns the previous table size, making it consistent with the table.grow instruction.

#1653

New Wasmtime-specific C APIs for working with tables were added which provide more detailed error information and which make growing a table more consistent with the table.grow instruction as well.

#1654

The C API now includes support for enabling logging in Wasmtime.

#1737

Changed

The WASI proc_exit function no longer exits the host process. It now unwinds the callstack back to the wasm entrypoint, and the exit value is available from the Trap::i32_exit_status method.

#1646

The WebAssembly multi-value proposal is now enabled by default.

#1667

The Rust API does not require a store provided during Module::new operation. The Module can be send accross threads and instantiate for a specific store. The Instance::new now requires the store.

#1761

---

0.16.0

Released 2020-04-29.

Added

• The Instance struct has new accessors, get_func, get_table, get_memory, and get_global for quickly looking up exported functions, tables, memories, and globals by name. #1524

• The C API has a number of new wasmtime_* functions which return error objects to get detailed error information when an API fails. #1467

• Users now have fine-grained control over creation of instances of Memory with a new MemoryCreator trait. #1400

• Go bindings for Wasmtime are now available. #1481

• APIs for looking up values in a Linker have been added. #1480

• Preliminary support for AArch64, also known as ARM64. #1581

Changed

• Instance::exports now returns Export objects which contain the names of the exports in addition to their Extern definitions, so it's no longer necessary to use Module::exports to obtain the export names. #1524

• The Func::call API has changed its error type from Trap to anyhow::Error to distinguish between wasm traps and runtime violations (like the wrong number of parameters). #1467

• A number of wasmtime_linker_* and wasmtime_config_* C APIs have new type signatures which reflect returning errors. #1467

• Bindings for .NET have moved to https://github.com/bytecodealliance/wasmtime-dotnet. #1477

• Passing too many imports to Instance::new is now considered an error. #1478

Fixed

• Spurious segfaults due to out-of-stack conditions when handling signals have been fixed. #1315

---

0.15.0

Released 2020-03-31.

Fixed

Full release produced for all artifacts to account for hiccups in 0.13.0 and 0.14.0.

---

0.14.0

This version ended up not getting a full release

Fixed

Fix build errors in wasi-common on Windows.

---

0.13.0

Released 2020-03-24.

Added

• Lots of documentation of wasmtime has been updated. Be sure to check out the book and API documentation!

• All wasmtime example programs are now in a top-level examples directory and are available in both C and Rust. #1286

• A wasmtime::Linker type was added to conveniently link link wasm modules together and create instances that reference one another. #1384

• Wasmtime now has "jitdump" support enabled by default which allows profiling wasm code on linux. #1310

• The wasmtime::Caller type now exists as a first-class way to access the caller's exports, namely memory, when implementing host APIs. This can be the first argument of functions defined with Func::new or Func::wrap which allows easily implementing methods which take a pointer into wasm memory. Note that this only works for accessing the caller's Memory for now and it must be exported. This will eventually be replaced with a more general-purpose mechanism like interface types. #1290

• The bulk memory proposal has been fully implemented. #1264 #976

• Virtual file support has been added to wasi-common. #701

• The C API has been enhanced with a Wasmtime-specific wasmtime_wat2wasm to parse *.wat files via the C API. #1206

Changed

• The wast and wasm2obj standalone binaries have been removed. They're available via the wasmtime wast and wasmtime wasm2obj subcommands. #1372

• The wasi-common crate now uses the new wiggle crate to auto-generate a trait which is implemented for the current wasi snapshot. #1202

• Wasmtime no longer has a dependency on a C++ compiler. #1365

• The Func::wrapN APIs have been consolidated into one Func::wrap API. #1363

• The Callable trait has been removed and now Func::new takes a closure directly. #1363

• The Cranelift repository has been merged into the Wasmtime repository.

• Support for interface types has been temporarily removed. #1292

• The exit code of the wasmtime CLI has changed if the program traps. #1274

• The wasmtime CLI now logs to stderr by default and the -d flag has been renamed to --log-to-file. #1266

• Values cannot cross Store objects, meaning you can't instantiate a module with values from different stores nor pass values from different stores into methods. #1016

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0.12.0

Released 2020-02-26.

Added

• Support for the WebAssembly text annotations proposal has been added. #998

• An initial C API for instantiating WASI modules has been added. #977

• A new suite of Func::getN functions have been added to the wasmtime API to call statically-known function signatures in a highly optimized fashion. #955

• Initial support for profiling JIT code through perf jitdump has been added. #360

• More CLI flags corresponding to proposed WebAssembly features have been added. #917

Changed

• The wasmtime CLI as well as embedding API will optimize WebAssembly code by default now. #973 #988

• The verifier pass in Cranelift is now no longer run by default when using the embedding API. #882

Fixed

• Code caching now accurately accounts for optimization levels, ensuring that if you ask for optimized code you're not accidentally handed unoptimized code from the cache. #974

• Automated releases for tags should be up and running again, along with automatic publication of the wasmtime Python package. #971