e7c8d23a42
* Implement. * Clean and doc * Collect base addresses instead of leaking them * Fix code for 1.25. * Simplify $assert * Use AbiParam::special. * Use &mut self in base_addr
103 lines
3.9 KiB
Rust
103 lines
3.9 KiB
Rust
//! An `Instance` contains all the runtime state used by execution of a wasm
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//! module.
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use cranelift_codegen::ir;
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use cranelift_wasm::GlobalIndex;
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use memory::LinearMemory;
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use wasmtime_environ::{DataInitializer, Module, TableElements};
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/// An Instance of a WebAssemby module.
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#[derive(Debug)]
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pub struct Instance {
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/// WebAssembly table data.
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pub tables: Vec<Vec<usize>>,
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/// WebAssembly linear memory data.
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pub memories: Vec<LinearMemory>,
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/// WebAssembly global variable data.
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pub globals: Vec<u8>,
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}
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impl Instance {
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/// Create a new `Instance`.
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pub fn new(module: &Module, data_initializers: &[DataInitializer]) -> Self {
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let mut result = Self {
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tables: Vec::new(),
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memories: Vec::new(),
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globals: Vec::new(),
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};
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result.instantiate_tables(module, &module.table_elements);
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result.instantiate_memories(module, data_initializers);
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result.instantiate_globals(module);
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result
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}
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/// Allocate memory in `self` for just the tables of the current module.
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fn instantiate_tables(&mut self, module: &Module, table_initializers: &[TableElements]) {
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debug_assert!(self.tables.is_empty());
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self.tables.reserve_exact(module.tables.len());
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for table in &module.tables {
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let len = table.size;
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let mut v = Vec::with_capacity(len);
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v.resize(len, 0);
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self.tables.push(v);
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}
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for init in table_initializers {
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debug_assert!(init.base.is_none(), "globalvar base not supported yet");
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let to_init =
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&mut self.tables[init.table_index][init.offset..init.offset + init.elements.len()];
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to_init.copy_from_slice(&init.elements);
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}
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}
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/// Allocate memory in `instance` for just the memories of the current module.
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fn instantiate_memories(&mut self, module: &Module, data_initializers: &[DataInitializer]) {
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debug_assert!(self.memories.is_empty());
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// Allocate the underlying memory and initialize it to all zeros.
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self.memories.reserve_exact(module.memories.len());
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for memory in &module.memories {
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let v = LinearMemory::new(memory.pages_count as u32, memory.maximum.map(|m| m as u32));
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self.memories.push(v);
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}
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for init in data_initializers {
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debug_assert!(init.base.is_none(), "globalvar base not supported yet");
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let mem_mut = self.memories[init.memory_index].as_mut();
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let to_init = &mut mem_mut[init.offset..init.offset + init.data.len()];
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to_init.copy_from_slice(init.data);
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}
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}
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/// Allocate memory in `instance` for just the globals of the current module,
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/// without any initializers applied yet.
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fn instantiate_globals(&mut self, module: &Module) {
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debug_assert!(self.globals.is_empty());
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// Allocate the underlying memory and initialize it to all zeros.
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let globals_data_size = module.globals.len() * 8;
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self.globals.resize(globals_data_size, 0);
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}
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/// Returns a mutable reference to a linear memory under the specified index.
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pub fn memory_mut(&mut self, memory_index: usize) -> &mut LinearMemory {
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self.memories
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.get_mut(memory_index)
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.unwrap_or_else(|| panic!("no memory for index {}", memory_index))
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}
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/// Returns a slice of the contents of allocated linear memory.
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pub fn inspect_memory(&self, memory_index: usize, address: usize, len: usize) -> &[u8] {
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&self
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.memories
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.get(memory_index)
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.unwrap_or_else(|| panic!("no memory for index {}", memory_index))
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.as_ref()[address..address + len]
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}
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/// Shows the value of a global variable.
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pub fn inspect_global(&self, global_index: GlobalIndex, ty: ir::Type) -> &[u8] {
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let offset = global_index * 8;
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let len = ty.bytes() as usize;
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&self.globals[offset..offset + len]
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}
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}
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