99 lines
3.6 KiB
Rust
99 lines
3.6 KiB
Rust
//! An `Instance` contains all the runtime state used by execution of a wasm
|
|
//! module.
|
|
|
|
use cranelift_codegen::ir;
|
|
use cranelift_wasm::GlobalIndex;
|
|
use module::{Module, TableElements};
|
|
use DataInitializer;
|
|
|
|
const PAGE_SIZE: usize = 65536;
|
|
|
|
/// An Instance of a WebAssemby module.
|
|
#[derive(Debug)]
|
|
pub struct Instance {
|
|
/// WebAssembly table data.
|
|
pub tables: Vec<Vec<usize>>,
|
|
|
|
/// WebAssembly linear memory data.
|
|
pub memories: Vec<Vec<u8>>,
|
|
|
|
/// WebAssembly global variable data.
|
|
pub globals: Vec<u8>,
|
|
}
|
|
|
|
impl Instance {
|
|
/// Create a new `Instance`.
|
|
pub fn new(module: &Module, data_initializers: &[DataInitializer]) -> Self {
|
|
let mut result = Self {
|
|
tables: Vec::new(),
|
|
memories: Vec::new(),
|
|
globals: Vec::new(),
|
|
};
|
|
result.instantiate_tables(module, &module.table_elements);
|
|
result.instantiate_memories(module, data_initializers);
|
|
result.instantiate_globals(module);
|
|
result
|
|
}
|
|
|
|
/// Allocate memory in `self` for just the tables of the current module.
|
|
fn instantiate_tables(&mut self, module: &Module, table_initializers: &[TableElements]) {
|
|
debug_assert!(self.tables.is_empty());
|
|
self.tables.reserve_exact(module.tables.len());
|
|
for table in &module.tables {
|
|
let len = table.size;
|
|
let mut v = Vec::with_capacity(len);
|
|
v.resize(len, 0);
|
|
self.tables.push(v);
|
|
}
|
|
for init in table_initializers {
|
|
debug_assert!(init.base.is_none(), "globalvar base not supported yet");
|
|
let to_init =
|
|
&mut self.tables[init.table_index][init.offset..init.offset + init.elements.len()];
|
|
to_init.copy_from_slice(&init.elements);
|
|
}
|
|
}
|
|
|
|
/// Allocate memory in `instance` for just the memories of the current module.
|
|
fn instantiate_memories(&mut self, module: &Module, data_initializers: &[DataInitializer]) {
|
|
debug_assert!(self.memories.is_empty());
|
|
// Allocate the underlying memory and initialize it to all zeros.
|
|
self.memories.reserve_exact(module.memories.len());
|
|
for memory in &module.memories {
|
|
let len = memory.pages_count * PAGE_SIZE;
|
|
let mut v = Vec::with_capacity(len);
|
|
v.resize(len, 0);
|
|
self.memories.push(v);
|
|
}
|
|
for init in data_initializers {
|
|
debug_assert!(init.base.is_none(), "globalvar base not supported yet");
|
|
let to_init =
|
|
&mut self.memories[init.memory_index][init.offset..init.offset + init.data.len()];
|
|
to_init.copy_from_slice(init.data);
|
|
}
|
|
}
|
|
|
|
/// Allocate memory in `instance` for just the globals of the current module,
|
|
/// without any initializers applied yet.
|
|
fn instantiate_globals(&mut self, module: &Module) {
|
|
debug_assert!(self.globals.is_empty());
|
|
// Allocate the underlying memory and initialize it to all zeros.
|
|
let globals_data_size = module.globals.len() * 8;
|
|
self.globals.resize(globals_data_size, 0);
|
|
}
|
|
|
|
/// Returns a slice of the contents of allocated linear memory.
|
|
pub fn inspect_memory(&self, memory_index: usize, address: usize, len: usize) -> &[u8] {
|
|
&self.memories
|
|
.get(memory_index)
|
|
.unwrap_or_else(|| panic!("no memory for index {}", memory_index))
|
|
[address..address + len]
|
|
}
|
|
|
|
/// Shows the value of a global variable.
|
|
pub fn inspect_global(&self, global_index: GlobalIndex, ty: ir::Type) -> &[u8] {
|
|
let offset = global_index * 8;
|
|
let len = ty.bytes() as usize;
|
|
&self.globals[offset..offset + len]
|
|
}
|
|
}
|