Struct Tnum 

pub struct Tnum { /* private fields */ }

Tracking number

Tracks on a bit-by-bit level whether we know the value of a bit & what that value is (if known).

References:

• Linux’s production implementation: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/bpf/tnum.c
• Linux verifier documentation: https://docs.kernel.org/bpf/verifier.html#register-value-tracking
• https://bitmath.blogspot.com/2013/08/addition-in-bitfield-domain.html
• https://bitmath.blogspot.com/2014/02/addition-in-bitfield-domain-alternative.html
• “Abstract Domains for Bit-Level Machine Integer and Floating-point Operations” (paper)
• https://www.omnimaga.org/other-computer-languages-help/addition-in-the-bitfield-domain/

Implementations

impl Tnum

pub const fn empty() -> Self

The empty set.

pub const fn from_parts(value: u64, mask: u64) -> Self

Construct a tracking number from its known value and unknown-bit mask.

Value bits covered by the mask are cleared to maintain the canonical value & mask == 0 representation.

pub const fn from_value(value: u64) -> Self

pub const fn parts(&self) -> Option<(u64, u64)>

Return the canonical (known_value, unknown_mask) representation.

pub const fn is_const(&self) -> bool

pub const fn value(&self) -> Option<u64>

pub const fn contains_value(&self, value: u64) -> bool

Whether this abstract value includes value.

pub const fn union(self, other: Self) -> Self

Return the least tracking number containing both operands.

pub const fn intersection(self, other: Self) -> Self

Return the values represented by both operands.

pub const fn is_defined(&self) -> bool

pub const fn contains(&self, other: Self) -> bool

Whether this tracking number includes every value in other.

pub const fn has_value(&self) -> bool

pub const fn min_value(&self) -> Option<u64>

pub const fn max_value(&self) -> Option<u64>

pub const fn unsigned_bounds(&self) -> (u64, u64)

pub const fn signed_bounds(&self) -> (i64, i64)

pub const fn bit_not(self) -> Self

pub const fn bit_or(self, other: Self) -> Self

pub const fn bit_and(self, other: Self) -> Self

pub const fn bit_xor(self, other: Self) -> Self

pub const fn shift_left(self, shift: u8) -> Self

pub const fn shift_right(self, shift: u8) -> Self

pub const fn add(self, other: Self) -> Self

Trait Implementations

impl Add for Tnum

type Output = Tnum

The resulting type after applying the + operator.

fn add(self, other: Self) -> Self::Output

Performs the + operation.

impl BitAnd for Tnum

type Output = Tnum

The resulting type after applying the & operator.

fn bitand(self, other: Self) -> Self

Performs the & operation.

impl BitOr for Tnum

type Output = Tnum

The resulting type after applying the | operator.

fn bitor(self, other: Self) -> Self

Performs the | operation.

impl BitXor for Tnum

type Output = Tnum

The resulting type after applying the ^ operator.

fn bitxor(self, other: Self) -> Self

Performs the ^ operation.

impl Clone for Tnum

fn clone(&self) -> Tnum

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Tnum

impl Debug for Tnum

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Tnum

fn default() -> Self

Default is a completely unknown value

impl Eq for Tnum

impl Not for Tnum

type Output = Tnum

The resulting type after applying the ! operator.

fn not(self) -> Self

Performs the unary ! operation.

impl PartialEq for Tnum

fn eq(&self, other: &Tnum) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Shl<u8> for Tnum

type Output = Tnum

The resulting type after applying the << operator.

fn shl(self, shift: u8) -> Self

Performs the << operation.

impl Shr<u8> for Tnum

type Output = Tnum

The resulting type after applying the >> operator.

fn shr(self, shift: u8) -> Self

Performs the >> operation.

impl StructuralPartialEq for Tnum