rust/tests/mir-opt/building/async_await.a-{closure#0}.generator_resume.0.mir
Arpad Borsos 96931a787a
Transform async ResumeTy in generator transform
- Eliminates all the `get_context` calls that async lowering created.
- Replace all `Local` `ResumeTy` types with `&mut Context<'_>`.

The `Local`s that have their types replaced are:
- The `resume` argument itself.
- The argument to `get_context`.
- The yielded value of a `yield`.

The `ResumeTy` hides a `&mut Context<'_>` behind an unsafe raw pointer, and the
`get_context` function is being used to convert that back to a `&mut Context<'_>`.

Ideally the async lowering would not use the `ResumeTy`/`get_context` indirection,
but rather directly use `&mut Context<'_>`, however that would currently
lead to higher-kinded lifetime errors.
See <https://github.com/rust-lang/rust/issues/105501>.

The async lowering step and the type / lifetime inference / checking are
still using the `ResumeTy` indirection for the time being, and that indirection
is removed here. After this transform, the generator body only knows about `&mut Context<'_>`.
2023-01-19 09:03:05 +01:00

42 lines
2.0 KiB
Rust

// MIR for `a::{closure#0}` 0 generator_resume
/* generator_layout = GeneratorLayout {
field_tys: {},
variant_fields: {
Unresumed(0): [],
Returned (1): [],
Panicked (2): [],
},
storage_conflicts: BitMatrix(0x0) {},
} */
fn a::{closure#0}(_1: Pin<&mut [async fn body@$DIR/async_await.rs:11:14: 11:16]>, _2: &mut Context<'_>) -> Poll<()> {
debug _task_context => _4; // in scope 0 at $DIR/async_await.rs:+0:14: +0:16
let mut _0: std::task::Poll<()>; // return place in scope 0 at $DIR/async_await.rs:+0:14: +0:16
let mut _3: (); // in scope 0 at $DIR/async_await.rs:+0:14: +0:16
let mut _4: &mut std::task::Context<'_>; // in scope 0 at $DIR/async_await.rs:+0:14: +0:16
let mut _5: u32; // in scope 0 at $DIR/async_await.rs:+0:14: +0:16
bb0: {
_5 = discriminant((*(_1.0: &mut [async fn body@$DIR/async_await.rs:11:14: 11:16]))); // scope 0 at $DIR/async_await.rs:+0:14: +0:16
switchInt(move _5) -> [0: bb1, 1: bb2, otherwise: bb3]; // scope 0 at $DIR/async_await.rs:+0:14: +0:16
}
bb1: {
_4 = move _2; // scope 0 at $DIR/async_await.rs:+0:14: +0:16
_3 = const (); // scope 0 at $DIR/async_await.rs:+0:14: +0:16
Deinit(_0); // scope 0 at $DIR/async_await.rs:+0:16: +0:16
((_0 as Ready).0: ()) = move _3; // scope 0 at $DIR/async_await.rs:+0:16: +0:16
discriminant(_0) = 0; // scope 0 at $DIR/async_await.rs:+0:16: +0:16
discriminant((*(_1.0: &mut [async fn body@$DIR/async_await.rs:11:14: 11:16]))) = 1; // scope 0 at $DIR/async_await.rs:+0:16: +0:16
return; // scope 0 at $DIR/async_await.rs:+0:16: +0:16
}
bb2: {
assert(const false, "`async fn` resumed after completion") -> bb2; // scope 0 at $DIR/async_await.rs:+0:14: +0:16
}
bb3: {
unreachable; // scope 0 at $DIR/async_await.rs:+0:14: +0:16
}
}