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doc(runtime-core) Write more documentation.

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This commit is contained in:
Ivan Enderlin 2019-11-04 21:45:23 +01:00
parent 3435ce436b
commit 81326cee13
1 changed files with 49 additions and 3 deletions
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52
lib/runtime-core/src/typed_func.rs
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@ -208,7 +208,6 @@ where
}
/// Represents a function that can be used by WebAssembly.
#[allow(dead_code)]
pub struct Func<'a, Args = (), Rets = (), Inner: Kind = Wasm> {
inner: Inner,
func: NonNull<vm::Func>,
@ -492,7 +491,14 @@ macro_rules! impl_traits {
{
#[allow(non_snake_case)]
fn to_raw(self) -> (NonNull<vm::Func>, Option<NonNull<vm::FuncEnv>>) {
/// This is required for the llvm backend to be able to unwind through this function.
// The `wrap` function is a wrapper around the
// imported function. It manages the argument passed
// to the imported function (in this case, the
// `vmctx` along with the regular WebAssembly
// arguments), and it manages the trapping.
//
// It is also required for the LLVM backend to be
// able to unwind through this function.
#[cfg_attr(nightly, unwind(allowed))]
extern fn wrap<$( $x, )* Rets, Trap, FN>(
func_ctx: &mut vm::FuncCtx $( , $x: <$x as WasmExternType>::Native )*
@ -503,22 +509,36 @@ macro_rules! impl_traits {
Trap: TrapEarly<Rets>,
FN: Fn(&mut vm::Ctx, $( $x, )*) -> Trap,
{
// Extract `vm::Ctx` from `vm::FuncCtx`. The
// pointer is always non-null.
let vmctx = unsafe { func_ctx.vmctx.as_mut() };
// Extract `vm::FuncEnv` from `vm::FuncCtx`.
let func_env = func_ctx.func_env;
let func: &FN = match func_env {
// The imported function is a closure with a
// captured environment.
Some(func_env) => unsafe {
let func: NonNull<FN> = func_env.cast();
&*func.as_ptr()
},
// The imported function is a regular function
// or a closure without a captured
// environment.
None => unsafe { mem::transmute_copy(&()) }
};
// Catch unwind in case of errors.
let err = match panic::catch_unwind(
panic::AssertUnwindSafe(
|| {
func(vmctx $( , WasmExternType::from_native($x) )* ).report()
// ^^^^^ The imported function
// expects `vm::Ctx` as first
// argument; provide it.
}
)
) {
@ -530,11 +550,15 @@ macro_rules! impl_traits {
Err(err) => err,
};
// At this point, there is an error that needs to
// be trapped.
unsafe {
(&*vmctx.module).runnable_module.do_early_trap(err)
}
}
// Extract the captured environment of the imported
// function if any.
let func_env: Option<NonNull<vm::FuncEnv>> =
// `FN` is a function pointer, or a closure
// _without_ a captured environment.
@ -563,7 +587,14 @@ macro_rules! impl_traits {
{
#[allow(non_snake_case)]
fn to_raw(self) -> (NonNull<vm::Func>, Option<NonNull<vm::FuncEnv>>) {
/// This is required for the llvm backend to be able to unwind through this function.
// The `wrap` function is a wrapper around the
// imported function. It manages the argument passed
// to the imported function (in this case, only the
// regular WebAssembly arguments), and it manages the
// trapping.
//
// It is also required for the LLVM backend to be
// able to unwind through this function.
#[cfg_attr(nightly, unwind(allowed))]
extern fn wrap<$( $x, )* Rets, Trap, FN>(
func_ctx: &mut vm::FuncCtx $( , $x: <$x as WasmExternType>::Native )*
@ -574,18 +605,29 @@ macro_rules! impl_traits {
Trap: TrapEarly<Rets>,
FN: Fn($( $x, )*) -> Trap,
{
// Extract `vm::Ctx` from `vm::FuncCtx`. The
// pointer is always non-null.
let vmctx = unsafe { func_ctx.vmctx.as_mut() };
// Extract `vm::FuncEnv` from `vm::FuncCtx`.
let func_env = func_ctx.func_env;
let func: &FN = match func_env {
// The imported function is a closure with a
// captured environment.
Some(func_env) => unsafe {
let func: NonNull<FN> = func_env.cast();
&*func.as_ptr()
},
// The imported function is a regular function
// or a closure without a captured
// environment.
None => unsafe { mem::transmute_copy(&()) }
};
// Catch unwind in case of errors.
let err = match panic::catch_unwind(
panic::AssertUnwindSafe(
|| {
@ -601,11 +643,15 @@ macro_rules! impl_traits {
Err(err) => err,
};
// At this point, there is an error that needs to
// be trapped.
unsafe {
(&*vmctx.module).runnable_module.do_early_trap(err)
}
}
// Extract the captured environment of the imported
// function if any.
let func_env: Option<NonNull<vm::FuncEnv>> =
// `FN` is a function pointer, or a closure
// _without_ a captured environment.