Struct wasmtime_runtime::VMGlobalDefinition

#[repr(C, align(16))]
pub struct VMGlobalDefinition { /* private fields */ }

The storage for a WebAssembly global defined within the instance.

TODO: Pack the globals more densely, rather than using the same size for every type.

Implementations

impl VMGlobalDefinition

pub fn new() -> Self

Construct a VMGlobalDefinition.

Examples found in repository

src/instance.rs (line 997)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

pub unsafe fn as_i32(&self) -> &i32

Return a reference to the value as an i32.

pub unsafe fn as_i32_mut(&mut self) -> &mut i32

Return a mutable reference to the value as an i32.

Examples found in repository

src/instance.rs (line 1000)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

pub unsafe fn as_u32(&self) -> &u32

Return a reference to the value as a u32.

Examples found in repository

src/instance/allocator.rs (line 155)

fn get_table_init_start(init: &TableInitializer, instance: &Instance) -> Result<u32> {
    match init.base {
        Some(base) => {
            let val = unsafe {
                if let Some(def_index) = instance.module().defined_global_index(base) {
                    *instance.global(def_index).as_u32()
                } else {
                    *(*instance.imported_global(base).from).as_u32()
                }
            };

            init.offset
                .checked_add(val)
                .ok_or_else(|| anyhow!("element segment global base overflows"))
        }
        None => Ok(init.offset),
    }
}

fn check_table_init_bounds(instance: &mut Instance, module: &Module) -> Result<()> {
    match &module.table_initialization {
        TableInitialization::FuncTable { segments, .. }
        | TableInitialization::Segments { segments } => {
            for segment in segments {
                let table = unsafe { &*instance.get_table(segment.table_index) };
                let start = get_table_init_start(segment, instance)?;
                let start = usize::try_from(start).unwrap();
                let end = start.checked_add(segment.elements.len());

                match end {
                    Some(end) if end <= table.size() as usize => {
                        // Initializer is in bounds
                    }
                    _ => {
                        bail!("table out of bounds: elements segment does not fit")
                    }
                }
            }
        }
    }

    Ok(())
}

fn initialize_tables(instance: &mut Instance, module: &Module) -> Result<()> {
    // Note: if the module's table initializer state is in
    // FuncTable mode, we will lazily initialize tables based on
    // any statically-precomputed image of FuncIndexes, but there
    // may still be "leftover segments" that could not be
    // incorporated. So we have a unified handler here that
    // iterates over all segments (Segments mode) or leftover
    // segments (FuncTable mode) to initialize.
    match &module.table_initialization {
        TableInitialization::FuncTable { segments, .. }
        | TableInitialization::Segments { segments } => {
            for segment in segments {
                instance.table_init_segment(
                    segment.table_index,
                    &segment.elements,
                    get_table_init_start(segment, instance)?,
                    0,
                    segment.elements.len() as u32,
                )?;
            }
        }
    }

    Ok(())
}

fn get_memory_init_start(init: &MemoryInitializer, instance: &Instance) -> Result<u64> {
    match init.base {
        Some(base) => {
            let mem64 = instance.module().memory_plans[init.memory_index]
                .memory
                .memory64;
            let val = unsafe {
                let global = if let Some(def_index) = instance.module().defined_global_index(base) {
                    instance.global(def_index)
                } else {
                    &*instance.imported_global(base).from
                };
                if mem64 {
                    *global.as_u64()
                } else {
                    u64::from(*global.as_u32())
                }
            };

            init.offset
                .checked_add(val)
                .ok_or_else(|| anyhow!("data segment global base overflows"))
        }
        None => Ok(init.offset),
    }
}

fn check_memory_init_bounds(instance: &Instance, initializers: &[MemoryInitializer]) -> Result<()> {
    for init in initializers {
        let memory = instance.get_memory(init.memory_index);
        let start = get_memory_init_start(init, instance)?;
        let end = usize::try_from(start)
            .ok()
            .and_then(|start| start.checked_add(init.data.len()));

        match end {
            Some(end) if end <= memory.current_length() => {
                // Initializer is in bounds
            }
            _ => {
                bail!("memory out of bounds: data segment does not fit")
            }
        }
    }

    Ok(())
}

fn initialize_memories(instance: &mut Instance, module: &Module) -> Result<()> {
    let memory_size_in_pages =
        &|memory| (instance.get_memory(memory).current_length() as u64) / u64::from(WASM_PAGE_SIZE);

    // Loads the `global` value and returns it as a `u64`, but sign-extends
    // 32-bit globals which can be used as the base for 32-bit memories.
    let get_global_as_u64 = &|global| unsafe {
        let def = if let Some(def_index) = instance.module().defined_global_index(global) {
            instance.global(def_index)
        } else {
            &*instance.imported_global(global).from
        };
        if module.globals[global].wasm_ty == WasmType::I64 {
            *def.as_u64()
        } else {
            u64::from(*def.as_u32())
        }
    };

    // Delegates to the `init_memory` method which is sort of a duplicate of
    // `instance.memory_init_segment` but is used at compile-time in other
    // contexts so is shared here to have only one method of memory
    // initialization.
    //
    // This call to `init_memory` notably implements all the bells and whistles
    // so errors only happen if an out-of-bounds segment is found, in which case
    // a trap is returned.
    let ok = module.memory_initialization.init_memory(
        InitMemory::Runtime {
            memory_size_in_pages,
            get_global_as_u64,
        },
        &mut |memory_index, init| {
            // If this initializer applies to a defined memory but that memory
            // doesn't need initialization, due to something like copy-on-write
            // pre-initializing it via mmap magic, then this initializer can be
            // skipped entirely.
            if let Some(memory_index) = module.defined_memory_index(memory_index) {
                if !instance.memories[memory_index].needs_init() {
                    return true;
                }
            }
            let memory = instance.get_memory(memory_index);

            unsafe {
                let src = instance.wasm_data(init.data.clone());
                let dst = memory.base.add(usize::try_from(init.offset).unwrap());
                // FIXME audit whether this is safe in the presence of shared
                // memory
                // (https://github.com/bytecodealliance/wasmtime/issues/4203).
                ptr::copy_nonoverlapping(src.as_ptr(), dst, src.len())
            }
            true
        },
    );
    if !ok {
        return Err(Trap::MemoryOutOfBounds.into());
    }

    Ok(())
}

pub unsafe fn as_u32_mut(&mut self) -> &mut u32

Return a mutable reference to the value as an u32.

pub unsafe fn as_i64(&self) -> &i64

Return a reference to the value as an i64.

pub unsafe fn as_i64_mut(&mut self) -> &mut i64

Return a mutable reference to the value as an i64.

Examples found in repository

src/instance.rs (line 1001)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

pub unsafe fn as_u64(&self) -> &u64

Return a reference to the value as an u64.

Examples found in repository

src/instance/allocator.rs (line 233)

fn get_memory_init_start(init: &MemoryInitializer, instance: &Instance) -> Result<u64> {
    match init.base {
        Some(base) => {
            let mem64 = instance.module().memory_plans[init.memory_index]
                .memory
                .memory64;
            let val = unsafe {
                let global = if let Some(def_index) = instance.module().defined_global_index(base) {
                    instance.global(def_index)
                } else {
                    &*instance.imported_global(base).from
                };
                if mem64 {
                    *global.as_u64()
                } else {
                    u64::from(*global.as_u32())
                }
            };

            init.offset
                .checked_add(val)
                .ok_or_else(|| anyhow!("data segment global base overflows"))
        }
        None => Ok(init.offset),
    }
}

fn check_memory_init_bounds(instance: &Instance, initializers: &[MemoryInitializer]) -> Result<()> {
    for init in initializers {
        let memory = instance.get_memory(init.memory_index);
        let start = get_memory_init_start(init, instance)?;
        let end = usize::try_from(start)
            .ok()
            .and_then(|start| start.checked_add(init.data.len()));

        match end {
            Some(end) if end <= memory.current_length() => {
                // Initializer is in bounds
            }
            _ => {
                bail!("memory out of bounds: data segment does not fit")
            }
        }
    }

    Ok(())
}

fn initialize_memories(instance: &mut Instance, module: &Module) -> Result<()> {
    let memory_size_in_pages =
        &|memory| (instance.get_memory(memory).current_length() as u64) / u64::from(WASM_PAGE_SIZE);

    // Loads the `global` value and returns it as a `u64`, but sign-extends
    // 32-bit globals which can be used as the base for 32-bit memories.
    let get_global_as_u64 = &|global| unsafe {
        let def = if let Some(def_index) = instance.module().defined_global_index(global) {
            instance.global(def_index)
        } else {
            &*instance.imported_global(global).from
        };
        if module.globals[global].wasm_ty == WasmType::I64 {
            *def.as_u64()
        } else {
            u64::from(*def.as_u32())
        }
    };

    // Delegates to the `init_memory` method which is sort of a duplicate of
    // `instance.memory_init_segment` but is used at compile-time in other
    // contexts so is shared here to have only one method of memory
    // initialization.
    //
    // This call to `init_memory` notably implements all the bells and whistles
    // so errors only happen if an out-of-bounds segment is found, in which case
    // a trap is returned.
    let ok = module.memory_initialization.init_memory(
        InitMemory::Runtime {
            memory_size_in_pages,
            get_global_as_u64,
        },
        &mut |memory_index, init| {
            // If this initializer applies to a defined memory but that memory
            // doesn't need initialization, due to something like copy-on-write
            // pre-initializing it via mmap magic, then this initializer can be
            // skipped entirely.
            if let Some(memory_index) = module.defined_memory_index(memory_index) {
                if !instance.memories[memory_index].needs_init() {
                    return true;
                }
            }
            let memory = instance.get_memory(memory_index);

            unsafe {
                let src = instance.wasm_data(init.data.clone());
                let dst = memory.base.add(usize::try_from(init.offset).unwrap());
                // FIXME audit whether this is safe in the presence of shared
                // memory
                // (https://github.com/bytecodealliance/wasmtime/issues/4203).
                ptr::copy_nonoverlapping(src.as_ptr(), dst, src.len())
            }
            true
        },
    );
    if !ok {
        return Err(Trap::MemoryOutOfBounds.into());
    }

    Ok(())
}

pub unsafe fn as_u64_mut(&mut self) -> &mut u64

Return a mutable reference to the value as an u64.

pub unsafe fn as_f32(&self) -> &f32

Return a reference to the value as an f32.

pub unsafe fn as_f32_mut(&mut self) -> &mut f32

Return a mutable reference to the value as an f32.

pub unsafe fn as_f32_bits(&self) -> &u32

Return a reference to the value as f32 bits.

pub unsafe fn as_f32_bits_mut(&mut self) -> &mut u32

Return a mutable reference to the value as f32 bits.

Examples found in repository

src/instance.rs (line 1002)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

pub unsafe fn as_f64(&self) -> &f64

Return a reference to the value as an f64.

pub unsafe fn as_f64_mut(&mut self) -> &mut f64

Return a mutable reference to the value as an f64.

pub unsafe fn as_f64_bits(&self) -> &u64

Return a reference to the value as f64 bits.

pub unsafe fn as_f64_bits_mut(&mut self) -> &mut u64

Return a mutable reference to the value as f64 bits.

Examples found in repository

src/instance.rs (line 1003)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

pub unsafe fn as_u128(&self) -> &u128

Return a reference to the value as an u128.

pub unsafe fn as_u128_mut(&mut self) -> &mut u128

Return a mutable reference to the value as an u128.

Examples found in repository

src/instance.rs (line 1004)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

pub unsafe fn as_u128_bits(&self) -> &[u8; 16]

Return a reference to the value as u128 bits.

pub unsafe fn as_u128_bits_mut(&mut self) -> &mut [u8; 16]

Return a mutable reference to the value as u128 bits.

pub unsafe fn as_externref(&self) -> &Option<VMExternRef>

Return a reference to the value as an externref.

Examples found in repository

src/libcalls.rs (line 401)

unsafe fn externref_global_get(vmctx: *mut VMContext, index: u32) -> *mut u8 {
    let index = GlobalIndex::from_u32(index);
    let instance = (*vmctx).instance();
    let global = instance.defined_or_imported_global_ptr(index);
    match (*global).as_externref().clone() {
        None => ptr::null_mut(),
        Some(externref) => {
            let raw = externref.as_raw();
            let (activations_table, module_info_lookup) =
                (*instance.store()).externref_activations_table();
            activations_table.insert_with_gc(externref, module_info_lookup);
            raw
        }
    }
}

src/instance.rs (line 1016)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

pub unsafe fn as_externref_mut(&mut self) -> &mut Option<VMExternRef>

Return a mutable reference to the value as an externref.

Examples found in repository

src/libcalls.rs (line 429)

unsafe fn externref_global_set(vmctx: *mut VMContext, index: u32, externref: *mut u8) {
    let externref = if externref.is_null() {
        None
    } else {
        Some(VMExternRef::clone_from_raw(externref))
    };

    let index = GlobalIndex::from_u32(index);
    let instance = (*vmctx).instance();
    let global = instance.defined_or_imported_global_ptr(index);

    // Swap the new `externref` value into the global before we drop the old
    // value. This protects against an `externref` with a `Drop` implementation
    // that calls back into Wasm and touches this global again (we want to avoid
    // it observing a halfway-deinitialized value).
    let old = mem::replace((*global).as_externref_mut(), externref);
    drop(old);
}

src/instance.rs (line 1016)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }
}

impl Drop for Instance {
    fn drop(&mut self) {
        // Drop any defined globals
        for (idx, global) in self.module().globals.iter() {
            let idx = match self.module().defined_global_index(idx) {
                Some(idx) => idx,
                None => continue,
            };
            match global.wasm_ty {
                // For now only externref globals need to get destroyed
                WasmType::ExternRef => {}
                _ => continue,
            }
            unsafe {
                drop((*self.global_ptr(idx)).as_externref_mut().take());
            }
        }
    }

pub unsafe fn as_anyfunc(&self) -> *const VMCallerCheckedAnyfunc

Return a reference to the value as an anyfunc.

pub unsafe fn as_anyfunc_mut(&mut self) -> &mut *const VMCallerCheckedAnyfunc

Return a mutable reference to the value as an anyfunc.

Examples found in repository

src/instance.rs (line 1022)

    unsafe fn initialize_vmctx_globals(&mut self, module: &Module) {
        let num_imports = module.num_imported_globals;
        for (index, global) in module.globals.iter().skip(num_imports) {
            let def_index = module.defined_global_index(index).unwrap();
            let to = self.global_ptr(def_index);

            // Initialize the global before writing to it
            ptr::write(to, VMGlobalDefinition::new());

            match global.initializer {
                GlobalInit::I32Const(x) => *(*to).as_i32_mut() = x,
                GlobalInit::I64Const(x) => *(*to).as_i64_mut() = x,
                GlobalInit::F32Const(x) => *(*to).as_f32_bits_mut() = x,
                GlobalInit::F64Const(x) => *(*to).as_f64_bits_mut() = x,
                GlobalInit::V128Const(x) => *(*to).as_u128_mut() = x,
                GlobalInit::GetGlobal(x) => {
                    let from = if let Some(def_x) = module.defined_global_index(x) {
                        self.global(def_x)
                    } else {
                        &*self.imported_global(x).from
                    };
                    // Globals of type `externref` need to manage the reference
                    // count as values move between globals, everything else is just
                    // copy-able bits.
                    match global.wasm_ty {
                        WasmType::ExternRef => {
                            *(*to).as_externref_mut() = from.as_externref().clone()
                        }
                        _ => ptr::copy_nonoverlapping(from, to, 1),
                    }
                }
                GlobalInit::RefFunc(f) => {
                    *(*to).as_anyfunc_mut() = self.get_caller_checked_anyfunc(f).unwrap()
                        as *const VMCallerCheckedAnyfunc;
                }
                GlobalInit::RefNullConst => match global.wasm_ty {
                    // `VMGlobalDefinition::new()` already zeroed out the bits
                    WasmType::FuncRef => {}
                    WasmType::ExternRef => {}
                    ty => panic!("unsupported reference type for global: {:?}", ty),
                },
                GlobalInit::Import => panic!("locally-defined global initialized as import"),
            }
        }
    }

Trait Implementations

impl Debug for VMGlobalDefinition

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.