Struct wasmtime_jit::trampoline::ir::MemFlags [−][src]
Flags for memory operations like load/store.
Each of these flags introduce a limited form of undefined behavior. The flags each enable certain optimizations that need to make additional assumptions. Generally, the semantics of a program does not change when a flag is removed, but adding a flag will.
In addition, the flags determine the endianness of the memory access. By default, any memory access uses the native endianness determined by the target ISA. This can be overridden for individual accesses by explicitly specifying little- or big-endian semantics via the flags.
Implementations
impl MemFlags
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pub fn new() -> MemFlags
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Create a new empty set of flags.
pub fn trusted() -> MemFlags
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Create a set of flags representing an access from a “trusted” address, meaning it’s known to be aligned and non-trapping.
pub fn set_by_name(&mut self, name: &str) -> bool
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Set a flag bit by name.
Returns true if the flag was found and set, false for an unknown flag name. Will also return false when trying to set inconsistent endianness flags.
pub fn endianness(self, native_endianness: Endianness) -> Endianness
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Return endianness of the memory access. This will return the endianness explicitly specified by the flags if any, and will default to the native endianness otherwise. The native endianness has to be provided by the caller since it is not explicitly encoded in CLIF IR – this allows a front end to create IR without having to know the target endianness.
pub fn set_endianness(&mut self, endianness: Endianness)
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Set endianness of the memory access.
pub fn notrap(self) -> bool
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Test if the notrap
flag is set.
Normally, trapping is part of the semantics of a load/store operation. If the platform would cause a trap when accessing the effective address, the Cranelift memory operation is also required to trap.
The notrap
flag tells Cranelift that the memory is accessible, which means that
accesses will not trap. This makes it possible to delete an unused load or a dead store
instruction.
pub fn set_notrap(&mut self)
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Set the notrap
flag.
pub fn aligned(self) -> bool
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Test if the aligned
flag is set.
By default, Cranelift memory instructions work with any unaligned effective address. If the
aligned
flag is set, the instruction is permitted to trap or return a wrong result if the
effective address is misaligned.
pub fn set_aligned(&mut self)
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Set the aligned
flag.
pub fn readonly(self) -> bool
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Test if the readonly
flag is set.
Loads with this flag have no memory dependencies. This results in undefined behavior if the dereferenced memory is mutated at any time between when the function is called and when it is exited.
pub fn set_readonly(&mut self)
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Set the readonly
flag.
Trait Implementations
impl Clone for MemFlags
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impl Copy for MemFlags
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impl Debug for MemFlags
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impl Display for MemFlags
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impl Eq for MemFlags
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impl Hash for MemFlags
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pub fn hash<__H>(&self, state: &mut __H) where
__H: Hasher,
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__H: Hasher,
pub fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
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H: Hasher,
impl PartialEq<MemFlags> for MemFlags
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impl StructuralEq for MemFlags
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impl StructuralPartialEq for MemFlags
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Auto Trait Implementations
impl RefUnwindSafe for MemFlags
impl Send for MemFlags
impl Sync for MemFlags
impl Unpin for MemFlags
impl UnwindSafe for MemFlags
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> CallHasher for T where
T: Hash,
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T: Hash,
impl<Q, K> Equivalent<K> for Q where
K: Borrow<Q> + ?Sized,
Q: Eq + ?Sized,
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K: Borrow<Q> + ?Sized,
Q: Eq + ?Sized,
pub fn equivalent(&self, key: &K) -> bool
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> Pointable for T
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pub const ALIGN: usize
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type Init = T
The type for initializers.
pub unsafe fn init(init: <T as Pointable>::Init) -> usize
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pub unsafe fn deref<'a>(ptr: usize) -> &'a T
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pub unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T
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pub unsafe fn drop(ptr: usize)
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impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T> ToString for T where
T: Display + ?Sized,
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T: Display + ?Sized,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,