Trait wasmtime_environ::Compiler

pub trait Compiler: Send + Sync {
    // Required methods
    fn compile_function(
        &self,
        translation: &ModuleTranslation<'_>,
        index: DefinedFuncIndex,
        data: FunctionBodyData<'_>,
        types: &ModuleTypes
    ) -> Result<(WasmFunctionInfo, Box<dyn Any + Send>), CompileError>;
    fn compile_array_to_wasm_trampoline(
        &self,
        translation: &ModuleTranslation<'_>,
        types: &ModuleTypes,
        index: DefinedFuncIndex
    ) -> Result<Box<dyn Any + Send>, CompileError>;
    fn compile_native_to_wasm_trampoline(
        &self,
        translation: &ModuleTranslation<'_>,
        types: &ModuleTypes,
        index: DefinedFuncIndex
    ) -> Result<Box<dyn Any + Send>, CompileError>;
    fn compile_wasm_to_native_trampoline(
        &self,
        wasm_func_ty: &WasmFuncType
    ) -> Result<Box<dyn Any + Send>, CompileError>;
    fn append_code(
        &self,
        obj: &mut Object<'static>,
        funcs: &[(String, Box<dyn Any + Send>)],
        resolve_reloc: &dyn Fn(usize, FuncIndex) -> usize
    ) -> Result<Vec<(SymbolId, FunctionLoc)>>;
    fn emit_trampolines_for_array_call_host_func(
        &self,
        ty: &WasmFuncType,
        host_fn: usize,
        obj: &mut Object<'static>
    ) -> Result<(FunctionLoc, FunctionLoc)>;
    fn triple(&self) -> &Triple;
    fn flags(&self) -> BTreeMap<String, FlagValue>;
    fn isa_flags(&self) -> BTreeMap<String, FlagValue>;
    fn is_branch_protection_enabled(&self) -> bool;
    fn append_dwarf(
        &self,
        obj: &mut Object<'_>,
        translation: &ModuleTranslation<'_>,
        funcs: &PrimaryMap<DefinedFuncIndex, (SymbolId, &(dyn Any + Send))>
    ) -> Result<()>;

    // Provided methods
    fn object(&self, kind: ObjectKind) -> Result<Object<'static>> { ... }
    fn page_size_align(&self) -> u64 { ... }
    fn create_systemv_cie(&self) -> Option<CommonInformationEntry> { ... }
}

An implementation of a compiler which can compile WebAssembly functions to machine code and perform other miscellaneous tasks needed by the JIT runtime.

Required Methods

fn compile_function( &self, translation: &ModuleTranslation<'_>, index: DefinedFuncIndex, data: FunctionBodyData<'_>, types: &ModuleTypes ) -> Result<(WasmFunctionInfo, Box<dyn Any + Send>), CompileError>

Compiles the function index within translation.

The body of the function is available in data and configuration values are also passed in via tunables. Type information in translation is all relative to types.

fn compile_array_to_wasm_trampoline( &self, translation: &ModuleTranslation<'_>, types: &ModuleTypes, index: DefinedFuncIndex ) -> Result<Box<dyn Any + Send>, CompileError>

Compile a trampoline for an array-call host function caller calling the indexth Wasm function.

The trampoline should save the necessary state to record the host-to-Wasm transition (e.g. registers used for fast stack walking).

fn compile_native_to_wasm_trampoline( &self, translation: &ModuleTranslation<'_>, types: &ModuleTypes, index: DefinedFuncIndex ) -> Result<Box<dyn Any + Send>, CompileError>

Compile a trampoline for a native-call host function caller calling the indexth Wasm function.

The trampoline should save the necessary state to record the host-to-Wasm transition (e.g. registers used for fast stack walking).

fn compile_wasm_to_native_trampoline( &self, wasm_func_ty: &WasmFuncType ) -> Result<Box<dyn Any + Send>, CompileError>

Compile a trampoline for a Wasm caller calling a native callee with the given signature.

The trampoline should save the necessary state to record the Wasm-to-host transition (e.g. registers used for fast stack walking).

fn append_code( &self, obj: &mut Object<'static>, funcs: &[(String, Box<dyn Any + Send>)], resolve_reloc: &dyn Fn(usize, FuncIndex) -> usize ) -> Result<Vec<(SymbolId, FunctionLoc)>>

Appends a list of compiled functions to an in-memory object.

This function will receive the same Box<dyn Any> produced as part of compilation from functions like compile_function, compile_host_to_wasm_trampoline, and other component-related shims. Internally this will take all of these functions and add information to the object such as:

• Compiled code in a .text section
• Unwind information in Wasmtime-specific sections
• Relocations, if necessary, for the text section

Each function is accompanied with its desired symbol name and the return value of this function is the symbol for each function as well as where each function was placed within the object.

The resolve_reloc argument is intended to resolving relocations between function, chiefly resolving intra-module calls within one core wasm module. The closure here takes two arguments:

1. First, the index within funcs that is being resolved,

2. and next the FuncIndex which is the relocation target to resolve.

The return value is an index within funcs that the relocation points to.

fn emit_trampolines_for_array_call_host_func( &self, ty: &WasmFuncType, host_fn: usize, obj: &mut Object<'static> ) -> Result<(FunctionLoc, FunctionLoc)>

Inserts two trampolines into obj for a array-call host function:

1. A wasm-call trampoline: A trampoline that takes arguments in their wasm-call locations, moves them to their array-call locations, calls the array-call host function, and finally moves the return values from the array-call locations to the wasm-call return locations. Additionally, this trampoline manages the wasm-to-host state transition for the runtime.

2. A native-call trampoline: A trampoline that takes arguments in their native-call locations, moves them to their array-call locations, calls the array-call host function, and finally moves the return values from the array-call locations to the native-call return locations. Does not need to manage any wasm/host state transitions, since both caller and callee are on the host side.

This will configure the same sections as append_code, but will likely be much smaller.

The two returned FunctionLoc structures describe where to find these trampolines in the text section, respectively.

These trampolines are only valid for in-process JIT usage. They bake in the function pointer to the host code.

fn triple(&self) -> &Triple

Returns the target triple that this compiler is compiling for.

fn flags(&self) -> BTreeMap<String, FlagValue>

Returns a list of configured settings for this compiler.

fn isa_flags(&self) -> BTreeMap<String, FlagValue>

Same as Compiler::flags, but ISA-specific (a cranelift-ism)

fn is_branch_protection_enabled(&self) -> bool

Get a flag indicating whether branch protection is enabled.

fn append_dwarf( &self, obj: &mut Object<'_>, translation: &ModuleTranslation<'_>, funcs: &PrimaryMap<DefinedFuncIndex, (SymbolId, &(dyn Any + Send))> ) -> Result<()>

Appends generated DWARF sections to the obj specified for the compiled functions.

Provided Methods

fn object(&self, kind: ObjectKind) -> Result<Object<'static>>

Creates a new Object file which is used to build the results of a compilation into.

The returned object file will have an appropriate architecture/endianness for self.triple(), but at this time it is always an ELF file, regardless of target platform.

fn page_size_align(&self) -> u64

Returns the alignment necessary to align values to the page size of the compilation target. Note that this may be an upper-bound where the alignment is larger than necessary for some platforms since it may depend on the platform’s runtime configuration.

fn create_systemv_cie(&self) -> Option<CommonInformationEntry>

Creates a new System V Common Information Entry for the ISA.

Returns None if the ISA does not support System V unwind information.

Implementors