std::intrinsics - Rust (original) (raw)

🔬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 tohttps://github.com/rust-lang/rust/blob/master/compiler/rustc_const_eval/src/interpret/intrinsics.rsand 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.

fallbackExperimental

mirExperimental

Rustc internal tooling for hand-writing MIR.

simdExperimental

SIMD compiler intrinsics.

AggregateRawPtrExperimental

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 toval.

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.

contract_check_ensuresExperimental

Check if the post-condition cond has been met.

contract_check_requiresExperimental

Check if the pre-condition cond has been met.

contract_checksExperimental

Returns whether we should perform contract-checking at runtime.

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.

disjoint_bitor⚠Experimental

Combine two values which have no bits in common.

exact_div⚠Experimental

Performs an exact division, resulting in undefined behavior wherex % 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 Timplements 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’sUndefined 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 tocfg!(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 wheny < 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 wheny < 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 ofmin_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 ofmin_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 ofmin_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 2N, where N is the width of T in bits.

wrapping_mulExperimental

Returns (a * b) mod 2N, where N is the width of T in bits.

wrapping_subExperimental

Returns (a - b) mod 2N, 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.