pub struct AddMovesForPackedDrops;
Expand description

This pass moves values being dropped that are within a packed struct to a separate local before dropping them, to ensure that they are dropped from an aligned address.

For example, if we have something like

#[repr(packed)]
struct Foo {
    dealign: u8,
    data: Vec<u8>
}

let foo = ...;

We want to call drop_in_place::<Vec<u8>> on data from an aligned address. This means we can’t simply drop foo.data directly, because its address is not aligned.

Instead, we move foo.data to a local and drop that:

    storage.live(drop_temp)
    drop_temp = foo.data;
    drop(drop_temp) -> next
next:
    storage.dead(drop_temp)

The storage instructions are required to avoid stack space blowup.

Trait Implementations§

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impl<'tcx> MirPass<'tcx> for AddMovesForPackedDrops

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fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>)

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fn name(&self) -> &'static str

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fn profiler_name(&self) -> &'static str

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fn is_enabled(&self, _sess: &Session) -> bool

Returns true if this pass is enabled with the current combination of compiler flags.
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fn is_mir_dump_enabled(&self) -> bool

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 0 bytes