Module intrinsics

🔬This is a nightly-only experimental API. (core_intrinsics)

Expand description

Compiler intrinsics.

The corresponding definitions are in https://github.com/rust-lang/rust/blob/master/compiler/rustc_codegen_llvm/src/intrinsic.rs. The corresponding const implementations are in https://github.com/rust-lang/rust/blob/master/compiler/rustc_const_eval/src/interpret/intrinsics.rs.

§Const intrinsics

Note: any changes to the constness of intrinsics should be discussed with the language team. This includes changes in the stability of the constness.

In order to make an intrinsic usable at compile-time, it needs to be declared in the “new” style, i.e. as a #[rustc_intrinsic] function, not inside an extern block. Then copy the implementation from https://github.com/rust-lang/miri/blob/master/src/shims/intrinsics to https://github.com/rust-lang/rust/blob/master/compiler/rustc_const_eval/src/interpret/intrinsics.rs and make the intrinsic declaration a const fn.

If an intrinsic is supposed to be used from a const fn with a rustc_const_stable attribute, #[rustc_intrinsic_const_stable_indirect] needs to be added to the intrinsic. Such a change requires T-lang approval, because it may bake a feature into the language that cannot be replicated in user code without compiler support.

§Volatiles

The volatile intrinsics provide operations intended to act on I/O memory, which are guaranteed to not be reordered by the compiler across other volatile intrinsics. See the LLVM documentation on [volatile].

§Atomics

The atomic intrinsics provide common atomic operations on machine words, with multiple possible memory orderings. They obey the same semantics as C++11. See the LLVM documentation on [atomics].

A quick refresher on memory ordering:

Acquire - a barrier for acquiring a lock. Subsequent reads and writes take place after the barrier.
Release - a barrier for releasing a lock. Preceding reads and writes take place before the barrier.
Sequentially consistent - sequentially consistent operations are guaranteed to happen in order. This is the standard mode for working with atomic types and is equivalent to Java’s volatile.

§Unwinding

Rust intrinsics may, in general, unwind. If an intrinsic can never unwind, add the #[rustc_nounwind] attribute so that the compiler can make use of this fact.

However, even for intrinsics that may unwind, rustc assumes that a Rust intrinsics will never initiate a foreign (non-Rust) unwind, and thus for panic=abort we can always assume that these intrinsics cannot unwind.

Modules§

fallbackExperimental
mirExperimental: Rustc internal tooling for hand-writing MIR.
simdExperimental: SIMD compiler intrinsics.

Traits§

AggregateRawPtrExperimental

Functions§

copy^⚠Deprecated: Copies count * size_of::<T>() bytes from src to dst. The source and destination may overlap.
copy_nonoverlapping^⚠Deprecated: Copies count * size_of::<T>() bytes from src to dst. The source and destination must not overlap.
drop_in_place^⚠Deprecated
transmute^⚠Deprecated: Reinterprets the bits of a value of one type as another type.
write_bytes^⚠Deprecated: Sets count * size_of::<T>() bytes of memory starting at dst to val.
abortExperimental: Aborts the execution of the process.
add_with_overflowExperimental: Performs checked integer addition.
aggregate_raw_ptrExperimental: Lowers in MIR to Rvalue::Aggregate with AggregateKind::RawPtr.
arith_offset^⚠Experimental: Calculates the offset from a pointer, potentially wrapping.
assert_inhabitedExperimental: A guard for unsafe functions that cannot ever be executed if T is uninhabited: This will statically either panic, or do nothing.
assert_mem_uninitialized_validExperimental: A guard for std::mem::uninitialized. This will statically either panic, or do nothing.
assert_zero_validExperimental: A guard for unsafe functions that cannot ever be executed if T does not permit zero-initialization: This will statically either panic, or do nothing.
assume^⚠Experimental: Informs the optimizer that a condition is always true. If the condition is false, the behavior is undefined.
atomic_and_acqrel^⚠Experimental: Bitwise and with the current value, returning the previous value.
atomic_and_acquire^⚠Experimental: Bitwise and with the current value, returning the previous value.
atomic_and_relaxed^⚠Experimental: Bitwise and with the current value, returning the previous value.
atomic_and_release^⚠Experimental: Bitwise and with the current value, returning the previous value.
atomic_and_seqcst^⚠Experimental: Bitwise and with the current value, returning the previous value.
atomic_cxchg_acqrel_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_acqrel_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_acqrel_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_acquire_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_acquire_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_acquire_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_relaxed_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_relaxed_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_relaxed_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_release_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_release_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_release_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_seqcst_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_seqcst_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchg_seqcst_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_acqrel_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_acqrel_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_acqrel_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_acquire_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_acquire_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_acquire_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_relaxed_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_relaxed_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_relaxed_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_release_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_release_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_release_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_seqcst_acquire^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_seqcst_relaxed^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_cxchgweak_seqcst_seqcst^⚠Experimental: Stores a value if the current value is the same as the old value.
atomic_fence_acqrel^⚠Experimental: An atomic fence.
atomic_fence_acquire^⚠Experimental: An atomic fence.
atomic_fence_release^⚠Experimental: An atomic fence.
atomic_fence_seqcst^⚠Experimental: An atomic fence.
atomic_load_acquire^⚠Experimental: Loads the current value of the pointer.
atomic_load_relaxed^⚠Experimental: Loads the current value of the pointer.
atomic_load_seqcst^⚠Experimental: Loads the current value of the pointer.
atomic_load_unordered^⚠Experimental: Do NOT use this intrinsic; “unordered” operations do not exist in our memory model! In terms of the Rust Abstract Machine, this operation is equivalent to src.read(), i.e., it performs a non-atomic read.
atomic_max_acqrel^⚠Experimental: Maximum with the current value using a signed comparison.
atomic_max_acquire^⚠Experimental: Maximum with the current value using a signed comparison.
atomic_max_relaxed^⚠Experimental: Maximum with the current value.
atomic_max_release^⚠Experimental: Maximum with the current value using a signed comparison.
atomic_max_seqcst^⚠Experimental: Maximum with the current value using a signed comparison.
atomic_min_acqrel^⚠Experimental: Minimum with the current value using a signed comparison.
atomic_min_acquire^⚠Experimental: Minimum with the current value using a signed comparison.
atomic_min_relaxed^⚠Experimental: Minimum with the current value using a signed comparison.
atomic_min_release^⚠Experimental: Minimum with the current value using a signed comparison.
atomic_min_seqcst^⚠Experimental: Minimum with the current value using a signed comparison.
atomic_nand_acqrel^⚠Experimental: Bitwise nand with the current value, returning the previous value.
atomic_nand_acquire^⚠Experimental: Bitwise nand with the current value, returning the previous value.
atomic_nand_relaxed^⚠Experimental: Bitwise nand with the current value, returning the previous value.
atomic_nand_release^⚠Experimental: Bitwise nand with the current value, returning the previous value.
atomic_nand_seqcst^⚠Experimental: Bitwise nand with the current value, returning the previous value.
atomic_or_acqrel^⚠Experimental: Bitwise or with the current value, returning the previous value.
atomic_or_acquire^⚠Experimental: Bitwise or with the current value, returning the previous value.
atomic_or_relaxed^⚠Experimental: Bitwise or with the current value, returning the previous value.
atomic_or_release^⚠Experimental: Bitwise or with the current value, returning the previous value.
atomic_or_seqcst^⚠Experimental: Bitwise or with the current value, returning the previous value.
atomic_singlethreadfence_acqrel^⚠Experimental: A compiler-only memory barrier.
atomic_singlethreadfence_acquire^⚠Experimental: A compiler-only memory barrier.
atomic_singlethreadfence_release^⚠Experimental: A compiler-only memory barrier.
atomic_singlethreadfence_seqcst^⚠Experimental: A compiler-only memory barrier.
atomic_store_relaxed^⚠Experimental: Stores the value at the specified memory location.
atomic_store_release^⚠Experimental: Stores the value at the specified memory location.
atomic_store_seqcst^⚠Experimental: Stores the value at the specified memory location.
atomic_store_unordered^⚠Experimental: Do NOT use this intrinsic; “unordered” operations do not exist in our memory model! In terms of the Rust Abstract Machine, this operation is equivalent to dst.write(val), i.e., it performs a non-atomic write.
atomic_umax_acqrel^⚠Experimental: Maximum with the current value using an unsigned comparison.
atomic_umax_acquire^⚠Experimental: Maximum with the current value using an unsigned comparison.
atomic_umax_relaxed^⚠Experimental: Maximum with the current value using an unsigned comparison.
atomic_umax_release^⚠Experimental: Maximum with the current value using an unsigned comparison.
atomic_umax_seqcst^⚠Experimental: Maximum with the current value using an unsigned comparison.
atomic_umin_acqrel^⚠Experimental: Minimum with the current value using an unsigned comparison.
atomic_umin_acquire^⚠Experimental: Minimum with the current value using an unsigned comparison.
atomic_umin_relaxed^⚠Experimental: Minimum with the current value using an unsigned comparison.
atomic_umin_release^⚠Experimental: Minimum with the current value using an unsigned comparison.
atomic_umin_seqcst^⚠Experimental: Minimum with the current value using an unsigned comparison.
atomic_xadd_acqrel^⚠Experimental: Adds to the current value, returning the previous value.
atomic_xadd_acquire^⚠Experimental: Adds to the current value, returning the previous value.
atomic_xadd_relaxed^⚠Experimental: Adds to the current value, returning the previous value.
atomic_xadd_release^⚠Experimental: Adds to the current value, returning the previous value.
atomic_xadd_seqcst^⚠Experimental: Adds to the current value, returning the previous value.
atomic_xchg_acqrel^⚠Experimental: Stores the value at the specified memory location, returning the old value.
atomic_xchg_acquire^⚠Experimental: Stores the value at the specified memory location, returning the old value.
atomic_xchg_relaxed^⚠Experimental: Stores the value at the specified memory location, returning the old value.
atomic_xchg_release^⚠Experimental: Stores the value at the specified memory location, returning the old value.
atomic_xchg_seqcst^⚠Experimental: Stores the value at the specified memory location, returning the old value.
atomic_xor_acqrel^⚠Experimental: Bitwise xor with the current value, returning the previous value.
atomic_xor_acquire^⚠Experimental: Bitwise xor with the current value, returning the previous value.
atomic_xor_relaxed^⚠Experimental: Bitwise xor with the current value, returning the previous value.
atomic_xor_release^⚠Experimental: Bitwise xor with the current value, returning the previous value.
atomic_xor_seqcst^⚠Experimental: Bitwise xor with the current value, returning the previous value.
atomic_xsub_acqrel^⚠Experimental: Subtract from the current value, returning the previous value.
atomic_xsub_acquire^⚠Experimental: Subtract from the current value, returning the previous value.
atomic_xsub_relaxed^⚠Experimental: Subtract from the current value, returning the previous value.
atomic_xsub_release^⚠Experimental: Subtract from the current value, returning the previous value.
atomic_xsub_seqcst^⚠Experimental: Subtract from the current value, returning the previous value.
bitreverseExperimental: Reverses the bits in an integer type T.
black_boxExperimental: See documentation of std::hint::black_box for details.
breakpointExperimental: Executes a breakpoint trap, for inspection by a debugger.
bswapExperimental: Reverses the bytes in an integer type T.
caller_locationExperimental: Gets a reference to a static Location indicating where it was called.
carrying_mul_addExperimental: Performs full-width multiplication and addition with a carry: multiplier * multiplicand + addend + carry.
catch_unwind^⚠Experimental: Rust’s “try catch” construct for unwinding. Invokes the function pointer try_fn with the data pointer data, and calls catch_fn if unwinding occurs while try_fn runs.
ceilf16^⚠Experimental: Returns the smallest integer greater than or equal to an f16.
ceilf32^⚠Experimental: Returns the smallest integer greater than or equal to an f32.
ceilf64^⚠Experimental: Returns the smallest integer greater than or equal to an f64.
ceilf128^⚠Experimental: Returns the smallest integer greater than or equal to an f128.
cold_pathExperimental: Hints to the compiler that current code path is cold.
compare_bytes^⚠Experimental: Lexicographically compare [left, left + bytes) and [right, right + bytes) as unsigned bytes, returning negative if left is less, zero if all the bytes match, or positive if left is greater.
const_allocate^⚠Experimental: Allocates a block of memory at compile time. At runtime, just returns a null pointer.
const_deallocate^⚠Experimental: Deallocates a memory which allocated by intrinsics::const_allocate at compile time. At runtime, does nothing.
const_eval_selectExperimental: Selects which function to call depending on the context.
copysignf16^⚠Experimental: Copies the sign from y to x for f16 values.
copysignf32^⚠Experimental: Copies the sign from y to x for f32 values.
copysignf64^⚠Experimental: Copies the sign from y to x for f64 values.
copysignf128^⚠Experimental: Copies the sign from y to x for f128 values.
cosf16^⚠Experimental: Returns the cosine of an f16.
cosf32^⚠Experimental: Returns the cosine of an f32.
cosf64^⚠Experimental: Returns the cosine of an f64.
cosf128^⚠Experimental: Returns the cosine of an f128.
ctlzExperimental: Returns the number of leading unset bits (zeroes) in an integer type T.
ctlz_nonzero^⚠Experimental: Like ctlz, but extra-unsafe as it returns undef when given an x with value 0.
ctpopExperimental: Returns the number of bits set in an integer type T
cttzExperimental: Returns the number of trailing unset bits (zeroes) in an integer type T.
cttz_nonzero^⚠Experimental: Like cttz, but extra-unsafe as it returns undef when given an x with value 0.
discriminant_valueExperimental: Returns the value of the discriminant for the variant in ‘v’; if T has no discriminant, returns 0.
exact_div^⚠Experimental: Performs an exact division, resulting in undefined behavior where x % y != 0 or y == 0 or x == T::MIN && y == -1
exp2f16^⚠Experimental: Returns 2 raised to the power of an f16.
exp2f32^⚠Experimental: Returns 2 raised to the power of an f32.
exp2f64^⚠Experimental: Returns 2 raised to the power of an f64.
exp2f128^⚠Experimental: Returns 2 raised to the power of an f128.
expf16^⚠Experimental: Returns the exponential of an f16.
expf32^⚠Experimental: Returns the exponential of an f32.
expf64^⚠Experimental: Returns the exponential of an f64.
expf128^⚠Experimental: Returns the exponential of an f128.
fabsf16^⚠Experimental: Returns the absolute value of an f16.
fabsf32^⚠Experimental: Returns the absolute value of an f32.
fabsf64^⚠Experimental: Returns the absolute value of an f64.
fabsf128^⚠Experimental: Returns the absolute value of an f128.
fadd_algebraicExperimental: Float addition that allows optimizations based on algebraic rules.
fadd_fast^⚠Experimental: Float addition that allows optimizations based on algebraic rules. May assume inputs are finite.
fdiv_algebraicExperimental: Float division that allows optimizations based on algebraic rules.
fdiv_fast^⚠Experimental: Float division that allows optimizations based on algebraic rules. May assume inputs are finite.
float_to_int_unchecked^⚠Experimental: Converts with LLVM’s fptoui/fptosi, which may return undef for values out of range (https://github.com/rust-lang/rust/issues/10184)
floorf16^⚠Experimental: Returns the largest integer less than or equal to an f16.
floorf32^⚠Experimental: Returns the largest integer less than or equal to an f32.
floorf64^⚠Experimental: Returns the largest integer less than or equal to an f64.
floorf128^⚠Experimental: Returns the largest integer less than or equal to an f128.
fmaf16^⚠Experimental: Returns a * b + c for f16 values.
fmaf32^⚠Experimental: Returns a * b + c for f32 values.
fmaf64^⚠Experimental: Returns a * b + c for f64 values.
fmaf128^⚠Experimental: Returns a * b + c for f128 values.
fmul_algebraicExperimental: Float multiplication that allows optimizations based on algebraic rules.
fmul_fast^⚠Experimental: Float multiplication that allows optimizations based on algebraic rules. May assume inputs are finite.
fmuladdf16^⚠Experimental: Returns a * b + c for f16 values, non-deterministically executing either a fused multiply-add or two operations with rounding of the intermediate result.
fmuladdf32^⚠Experimental: Returns a * b + c for f32 values, non-deterministically executing either a fused multiply-add or two operations with rounding of the intermediate result.
fmuladdf64^⚠Experimental: Returns a * b + c for f64 values, non-deterministically executing either a fused multiply-add or two operations with rounding of the intermediate result.
fmuladdf128^⚠Experimental: Returns a * b + c for f128 values, non-deterministically executing either a fused multiply-add or two operations with rounding of the intermediate result.
forgetExperimental: Moves a value out of scope without running drop glue.
frem_algebraicExperimental: Float remainder that allows optimizations based on algebraic rules.
frem_fast^⚠Experimental: Float remainder that allows optimizations based on algebraic rules. May assume inputs are finite.
fsub_algebraicExperimental: Float subtraction that allows optimizations based on algebraic rules.
fsub_fast^⚠Experimental: Float subtraction that allows optimizations based on algebraic rules. May assume inputs are finite.
is_val_statically_knownExperimental: Returns whether the argument’s value is statically known at compile-time.
likelyExperimental: Hints to the compiler that branch condition is likely to be true. Returns the value passed to it.
log2f16^⚠Experimental: Returns the base 2 logarithm of an f16.
log2f32^⚠Experimental: Returns the base 2 logarithm of an f32.
log2f64^⚠Experimental: Returns the base 2 logarithm of an f64.
log2f128^⚠Experimental: Returns the base 2 logarithm of an f128.
log10f16^⚠Experimental: Returns the base 10 logarithm of an f16.
log10f32^⚠Experimental: Returns the base 10 logarithm of an f32.
log10f64^⚠Experimental: Returns the base 10 logarithm of an f64.
log10f128^⚠Experimental: Returns the base 10 logarithm of an f128.
logf16^⚠Experimental: Returns the natural logarithm of an f16.
logf32^⚠Experimental: Returns the natural logarithm of an f32.
logf64^⚠Experimental: Returns the natural logarithm of an f64.
logf128^⚠Experimental: Returns the natural logarithm of an f128.
maxnumf16Experimental: Returns the maximum of two f16 values.
maxnumf32Experimental: Returns the maximum of two f32 values.
maxnumf64Experimental: Returns the maximum of two f64 values.
maxnumf128Experimental: Returns the maximum of two f128 values.
min_align_ofExperimental: The minimum alignment of a type.
min_align_of_val^⚠Experimental: The required alignment of the referenced value.
minnumf16Experimental: Returns the minimum of two f16 values.
minnumf32Experimental: Returns the minimum of two f32 values.
minnumf64Experimental: Returns the minimum of two f64 values.
minnumf128Experimental: Returns the minimum of two f128 values.
mul_with_overflowExperimental: Performs checked integer multiplication
nearbyintf16^⚠Experimental: Returns the nearest integer to an f16. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
nearbyintf32^⚠Experimental: Returns the nearest integer to an f32. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
nearbyintf64^⚠Experimental: Returns the nearest integer to an f64. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
nearbyintf128^⚠Experimental: Returns the nearest integer to an f128. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
needs_dropExperimental: Returns true if the actual type given as T requires drop glue; returns false if the actual type provided for T implements Copy.
nontemporal_store^⚠Experimental: Emits a nontemporal store, which gives a hint to the CPU that the data should not be held in cache. Except for performance, this is fully equivalent to ptr.write(val).
offset^⚠Experimental: Calculates the offset from a pointer.
powf16^⚠Experimental: Raises an f16 to an f16 power.
powf32^⚠Experimental: Raises an f32 to an f32 power.
powf64^⚠Experimental: Raises an f64 to an f64 power.
powf128^⚠Experimental: Raises an f128 to an f128 power.
powif16^⚠Experimental: Raises an f16 to an integer power.
powif32^⚠Experimental: Raises an f32 to an integer power.
powif64^⚠Experimental: Raises an f64 to an integer power.
powif128^⚠Experimental: Raises an f128 to an integer power.
pref_align_of^⚠Experimental: The preferred alignment of a type.
prefetch_read_data^⚠Experimental: The prefetch intrinsic is a hint to the code generator to insert a prefetch instruction if supported; otherwise, it is a no-op. Prefetches have no effect on the behavior of the program but can change its performance characteristics.
prefetch_read_instruction^⚠Experimental: The prefetch intrinsic is a hint to the code generator to insert a prefetch instruction if supported; otherwise, it is a no-op. Prefetches have no effect on the behavior of the program but can change its performance characteristics.
prefetch_write_data^⚠Experimental: The prefetch intrinsic is a hint to the code generator to insert a prefetch instruction if supported; otherwise, it is a no-op. Prefetches have no effect on the behavior of the program but can change its performance characteristics.
prefetch_write_instruction^⚠Experimental: The prefetch intrinsic is a hint to the code generator to insert a prefetch instruction if supported; otherwise, it is a no-op. Prefetches have no effect on the behavior of the program but can change its performance characteristics.
ptr_guaranteed_cmpExperimental: See documentation of <*const T>::guaranteed_eq for details. Returns 2 if the result is unknown. Returns 1 if the pointers are guaranteed equal. Returns 0 if the pointers are guaranteed inequal.
ptr_maskExperimental: Masks out bits of the pointer according to a mask.
ptr_metadataExperimental: Lowers in MIR to Rvalue::UnaryOp with UnOp::PtrMetadata.
ptr_offset_from^⚠Experimental: See documentation of <*const T>::offset_from for details.
ptr_offset_from_unsigned^⚠Experimental: See documentation of <*const T>::sub_ptr for details.
raw_eq^⚠Experimental: Determines whether the raw bytes of the two values are equal.
read_via_copy^⚠Experimental: This is an implementation detail of crate::ptr::read and should not be used anywhere else. See its comments for why this exists.
rintf16^⚠Experimental: Returns the nearest integer to an f16. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
rintf32^⚠Experimental: Returns the nearest integer to an f32. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
rintf64^⚠Experimental: Returns the nearest integer to an f64. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
rintf128^⚠Experimental: Returns the nearest integer to an f128. Changing the rounding mode is not possible in Rust, so this rounds half-way cases to the number with an even least significant digit.
rotate_leftExperimental: Performs rotate left.
rotate_rightExperimental: Performs rotate right.
roundevenf16^⚠Experimental: Returns the nearest integer to an f16. Rounds half-way cases to the number with an even least significant digit.
roundevenf32^⚠Experimental: Returns the nearest integer to an f32. Rounds half-way cases to the number with an even least significant digit.
roundevenf64^⚠Experimental: Returns the nearest integer to an f64. Rounds half-way cases to the number with an even least significant digit.
roundevenf128^⚠Experimental: Returns the nearest integer to an f128. Rounds half-way cases to the number with an even least significant digit.
roundf16^⚠Experimental: Returns the nearest integer to an f16. Rounds half-way cases away from zero.
roundf32^⚠Experimental: Returns the nearest integer to an f32. Rounds half-way cases away from zero.
roundf64^⚠Experimental: Returns the nearest integer to an f64. Rounds half-way cases away from zero.
roundf128^⚠Experimental: Returns the nearest integer to an f128. Rounds half-way cases away from zero.
rustc_peekExperimental: Magic intrinsic that derives its meaning from attributes attached to the function.
saturating_addExperimental: Computes a + b, saturating at numeric bounds.
saturating_subExperimental: Computes a - b, saturating at numeric bounds.
select_unpredictableExperimental: Returns either true_val or false_val depending on condition b with a hint to the compiler that this condition is unlikely to be correctly predicted by a CPU’s branch predictor (e.g. a binary search).
sinf16^⚠Experimental: Returns the sine of an f16.
sinf32^⚠Experimental: Returns the sine of an f32.
sinf64^⚠Experimental: Returns the sine of an f64.
sinf128^⚠Experimental: Returns the sine of an f128.
size_ofExperimental: The size of a type in bytes.
size_of_val^⚠Experimental: The size of the referenced value in bytes.
sqrtf16^⚠Experimental: Returns the square root of an f16
sqrtf32^⚠Experimental: Returns the square root of an f32
sqrtf64^⚠Experimental: Returns the square root of an f64
sqrtf128^⚠Experimental: Returns the square root of an f128
sub_with_overflowExperimental: Performs checked integer subtraction
three_way_compareExperimental: Does a three-way comparison between the two integer arguments.
transmute_unchecked^⚠Experimental: Like transmute, but even less checked at compile-time: rather than giving an error for size_of::<Src>() != size_of::<Dst>(), it’s Undefined Behavior at runtime.
truncf16^⚠Experimental: Returns the integer part of an f16.
truncf32^⚠Experimental: Returns the integer part of an f32.
truncf64^⚠Experimental: Returns the integer part of an f64.
truncf128^⚠Experimental: Returns the integer part of an f128.
type_idExperimental: Gets an identifier which is globally unique to the specified type. This function will return the same value for a type regardless of whichever crate it is invoked in.
type_nameExperimental: Gets a static string slice containing the name of a type.
typed_swap_nonoverlapping^⚠Experimental: Non-overlapping typed swap of a single value.
ub_checksExperimental: Returns whether we should perform some UB-checking at runtime. This eventually evaluates to cfg!(ub_checks), but behaves different from cfg! when mixing crates built with different flags: if the crate has UB checks enabled or carries the #[rustc_preserve_ub_checks] attribute, evaluation is delayed until monomorphization (or until the call gets inlined into a crate that does not delay evaluation further); otherwise it can happen any time.
unaligned_volatile_load^⚠Experimental: Performs a volatile load from the src pointer The pointer is not required to be aligned.
unaligned_volatile_store^⚠Experimental: Performs a volatile store to the dst pointer. The pointer is not required to be aligned.
unchecked_add^⚠Experimental: Returns the result of an unchecked addition, resulting in undefined behavior when x + y > T::MAX or x + y < T::MIN.
unchecked_div^⚠Experimental: Performs an unchecked division, resulting in undefined behavior where y == 0 or x == T::MIN && y == -1
unchecked_mul^⚠Experimental: Returns the result of an unchecked multiplication, resulting in undefined behavior when x * y > T::MAX or x * y < T::MIN.
unchecked_rem^⚠Experimental: Returns the remainder of an unchecked division, resulting in undefined behavior when y == 0 or x == T::MIN && y == -1
unchecked_shl^⚠Experimental: Performs an unchecked left shift, resulting in undefined behavior when y < 0 or y >= N, where N is the width of T in bits.
unchecked_shr^⚠Experimental: Performs an unchecked right shift, resulting in undefined behavior when y < 0 or y >= N, where N is the width of T in bits.
unchecked_sub^⚠Experimental: Returns the result of an unchecked subtraction, resulting in undefined behavior when x - y > T::MAX or x - y < T::MIN.
unlikelyExperimental: Hints to the compiler that branch condition is likely to be false. Returns the value passed to it.
unreachable^⚠Experimental: Informs the optimizer that this point in the code is not reachable, enabling further optimizations.
variant_countExperimental: Returns the number of variants of the type T cast to a usize; if T has no variants, returns 0. Uninhabited variants will be counted.
volatile_copy_memory^⚠Experimental: Equivalent to the appropriate llvm.memmove.p0i8.0i8.* intrinsic, with a size of count * size_of::<T>() and an alignment of min_align_of::<T>()
volatile_copy_nonoverlapping_memory^⚠Experimental: Equivalent to the appropriate llvm.memcpy.p0i8.0i8.* intrinsic, with a size of count * size_of::<T>() and an alignment of min_align_of::<T>()
volatile_load^⚠Experimental: Performs a volatile load from the src pointer.
volatile_set_memory^⚠Experimental: Equivalent to the appropriate llvm.memset.p0i8.* intrinsic, with a size of count * size_of::<T>() and an alignment of min_align_of::<T>().
volatile_store^⚠Experimental: Performs a volatile store to the dst pointer.
vtable_align^⚠Experimental: The intrinsic will return the alignment stored in that vtable.
vtable_size^⚠Experimental: The intrinsic will return the size stored in that vtable.
wrapping_addExperimental: Returns (a + b) mod 2^N, where N is the width of T in bits.
wrapping_mulExperimental: Returns (a * b) mod 2^N, where N is the width of T in bits.
wrapping_subExperimental: Returns (a - b) mod 2^N, where N is the width of T in bits.
write_via_move^⚠Experimental: This is an implementation detail of crate::ptr::write and should not be used anywhere else. See its comments for why this exists.

Module intrinsicsCopy item path