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pub use self::instrs::ResumableHostError;
pub(crate) use self::stack::Stack;
use self::{
instrs::{dispatch_host_func, execute_instrs},
stack::CallFrame,
};
use crate::{
engine::{
bytecode::{InstructionPtr, Register, RegisterSpan},
CallParams,
CallResults,
EngineInner,
ResumableCallBase,
ResumableInvocation,
},
func::HostFuncEntity,
Error,
Func,
FuncEntity,
Store,
StoreContextMut,
};
#[cfg(doc)]
use crate::engine::StackLimits;
use super::code_map::CodeMap;
mod cache;
mod instrs;
mod stack;
impl EngineInner {
/// Executes the given [`Func`] with the given `params` and returns the `results`.
///
/// Uses the [`StoreContextMut`] for context information about the Wasm [`Store`].
///
/// # Errors
///
/// If the Wasm execution traps or runs out of resources.
pub fn execute_func<T, Results>(
&self,
ctx: StoreContextMut<T>,
func: &Func,
params: impl CallParams,
results: Results,
) -> Result<<Results as CallResults>::Results, Error>
where
Results: CallResults,
{
let mut stack = self.stacks.lock().reuse_or_new();
let results = EngineExecutor::new(&self.code_map, &mut stack)
.execute_root_func(ctx.store, func, params, results)
.map_err(|error| match error.into_resumable() {
Ok(error) => error.into_error(),
Err(error) => error,
});
self.stacks.lock().recycle(stack);
results
}
/// Executes the given [`Func`] resumably with the given `params` and returns the `results`.
///
/// Uses the [`StoreContextMut`] for context information about the Wasm [`Store`].
///
/// # Errors
///
/// If the Wasm execution traps or runs out of resources.
pub fn execute_func_resumable<T, Results>(
&self,
ctx: StoreContextMut<T>,
func: &Func,
params: impl CallParams,
results: Results,
) -> Result<ResumableCallBase<<Results as CallResults>::Results>, Error>
where
Results: CallResults,
{
let store = ctx.store;
let mut stack = self.stacks.lock().reuse_or_new();
let results = EngineExecutor::new(&self.code_map, &mut stack)
.execute_root_func(store, func, params, results);
match results {
Ok(results) => {
self.stacks.lock().recycle(stack);
Ok(ResumableCallBase::Finished(results))
}
Err(error) => match error.into_resumable() {
Ok(error) => {
let host_func = *error.host_func();
let caller_results = *error.caller_results();
let host_error = error.into_error();
Ok(ResumableCallBase::Resumable(ResumableInvocation::new(
store.engine().clone(),
*func,
host_func,
host_error,
caller_results,
stack,
)))
}
Err(error) => {
self.stacks.lock().recycle(stack);
Err(error)
}
},
}
}
/// Resumes the given [`Func`] with the given `params` and returns the `results`.
///
/// Uses the [`StoreContextMut`] for context information about the Wasm [`Store`].
///
/// # Errors
///
/// If the Wasm execution traps or runs out of resources.
pub fn resume_func<T, Results>(
&self,
ctx: StoreContextMut<T>,
mut invocation: ResumableInvocation,
params: impl CallParams,
results: Results,
) -> Result<ResumableCallBase<<Results as CallResults>::Results>, Error>
where
Results: CallResults,
{
let host_func = invocation.host_func();
let caller_results = invocation.caller_results();
let results = EngineExecutor::new(&self.code_map, &mut invocation.stack).resume_func(
ctx.store,
host_func,
params,
caller_results,
results,
);
match results {
Ok(results) => {
self.stacks.lock().recycle(invocation.take_stack());
Ok(ResumableCallBase::Finished(results))
}
Err(error) => match error.into_resumable() {
Ok(error) => {
let host_func = *error.host_func();
let caller_results = *error.caller_results();
invocation.update(host_func, error.into_error(), caller_results);
Ok(ResumableCallBase::Resumable(invocation))
}
Err(error) => {
self.stacks.lock().recycle(invocation.take_stack());
Err(error)
}
},
}
}
}
/// The internal state of the Wasmi engine.
#[derive(Debug)]
pub struct EngineExecutor<'engine> {
/// Shared and reusable generic engine resources.
code_map: &'engine CodeMap,
/// The value and call stacks.
stack: &'engine mut Stack,
}
/// Convenience function that does nothing to its `&mut` parameter.
#[inline]
fn do_nothing<T>(_: &mut T) {}
impl<'engine> EngineExecutor<'engine> {
/// Creates a new [`EngineExecutor`] with the given [`StackLimits`].
fn new(code_map: &'engine CodeMap, stack: &'engine mut Stack) -> Self {
Self { code_map, stack }
}
/// Executes the given [`Func`] using the given `params`.
///
/// Stores the execution result into `results` upon a successful execution.
///
/// # Errors
///
/// - If the given `params` do not match the expected parameters of `func`.
/// - If the given `results` do not match the the length of the expected results of `func`.
/// - When encountering a Wasm or host trap during the execution of `func`.
fn execute_root_func<T, Results>(
&mut self,
store: &mut Store<T>,
func: &Func,
params: impl CallParams,
results: Results,
) -> Result<<Results as CallResults>::Results, Error>
where
Results: CallResults,
{
self.stack.reset();
match store.inner.resolve_func(func) {
FuncEntity::Wasm(wasm_func) => {
// We reserve space on the stack to write the results of the root function execution.
let len_results = results.len_results();
self.stack.values.extend_by(len_results, do_nothing)?;
let instance = *wasm_func.instance();
let engine_func = wasm_func.func_body();
let compiled_func = self
.code_map
.get(Some(store.inner.fuel_mut()), engine_func)?;
let (mut uninit_params, offsets) = self
.stack
.values
.alloc_call_frame(compiled_func, do_nothing)?;
for value in params.call_params() {
unsafe { uninit_params.init_next(value) };
}
uninit_params.init_zeroes();
self.stack.calls.push(
CallFrame::new(
InstructionPtr::new(compiled_func.instrs().as_ptr()),
offsets,
RegisterSpan::new(Register::from_i16(0)),
),
Some(instance),
)?;
self.execute_func(store)?;
}
FuncEntity::Host(host_func) => {
// The host function signature is required for properly
// adjusting, inspecting and manipulating the value stack.
// In case the host function returns more values than it takes
// we are required to extend the value stack.
let len_params = host_func.len_params();
let len_results = host_func.len_results();
let max_inout = len_params.max(len_results);
let uninit = self
.stack
.values
.extend_by(usize::from(max_inout), do_nothing)?;
for (uninit, param) in uninit.iter_mut().zip(params.call_params()) {
uninit.write(param);
}
let host_func = *host_func;
self.dispatch_host_func(store, host_func)?;
}
};
let results = self.write_results_back(results);
Ok(results)
}
/// Resumes the execution of the given [`Func`] using `params`.
///
/// Stores the execution result into `results` upon a successful execution.
///
/// # Errors
///
/// - If the given `params` do not match the expected parameters of `func`.
/// - If the given `results` do not match the the length of the expected results of `func`.
/// - When encountering a Wasm or host trap during the execution of `func`.
fn resume_func<T, Results>(
&mut self,
store: &mut Store<T>,
_host_func: Func,
params: impl CallParams,
caller_results: RegisterSpan,
results: Results,
) -> Result<<Results as CallResults>::Results, Error>
where
Results: CallResults,
{
let caller = self
.stack
.calls
.peek()
.expect("must have caller call frame on stack upon function resumption");
let mut caller_sp = unsafe { self.stack.values.stack_ptr_at(caller.base_offset()) };
let call_params = params.call_params();
let len_params = call_params.len();
for (result, param) in caller_results.iter(len_params).zip(call_params) {
unsafe { caller_sp.set(result, param) };
}
self.execute_func(store)?;
let results = self.write_results_back(results);
Ok(results)
}
/// Executes the top most Wasm function on the [`Stack`] until the [`Stack`] is empty.
///
/// # Errors
///
/// When encountering a Wasm or host trap during execution.
#[inline(always)]
fn execute_func<T>(&mut self, store: &mut Store<T>) -> Result<(), Error> {
execute_instrs(store, self.stack, self.code_map)
}
/// Convenience forwarder to [`dispatch_host_func`].
#[inline(always)]
fn dispatch_host_func<T>(
&mut self,
store: &mut Store<T>,
host_func: HostFuncEntity,
) -> Result<(), Error> {
dispatch_host_func(store, &mut self.stack.values, host_func, None)?;
Ok(())
}
/// Writes the results of the function execution back into the `results` buffer.
///
/// # Note
///
/// The value stack is empty after this operation.
///
/// # Panics
///
/// - If the `results` buffer length does not match the remaining amount of stack values.
#[inline(always)]
fn write_results_back<Results>(&mut self, results: Results) -> <Results as CallResults>::Results
where
Results: CallResults,
{
let len_results = results.len_results();
results.call_results(&self.stack.values.as_slice()[..len_results])
}
}