Struct cranelift_codegen::ir::constant::ConstantData

pub struct ConstantData(_);

This type describes the actual constant data. Note that the bytes stored in this structure are expected to be in little-endian order; this is due to ease-of-use when interacting with WebAssembly values, which are little-endian by design.

Implementations

impl ConstantData

pub fn len(&self) -> usize

Return the number of bytes in the constant.

Examples found in repository

src/ir/constant.rs (line 94)

    pub fn expand_to(mut self, expected_size: usize) -> Self {
        if self.len() > expected_size {
            panic!(
                "The constant data is already expanded beyond {} bytes",
                expected_size
            )
        }
        self.0.resize(expected_size, 0);
        self
    }
}

impl fmt::Display for ConstantData {
    /// Print the constant data in hexadecimal format, e.g. 0x000102030405060708090a0b0c0d0e0f.
    /// This function will flip the stored order of bytes--little-endian--to the more readable
    /// big-endian ordering.
    ///
    /// ```
    /// use cranelift_codegen::ir::ConstantData;
    /// let data = ConstantData::from([3, 2, 1, 0, 0].as_ref()); // note the little-endian order
    /// assert_eq!(data.to_string(), "0x0000010203");
    /// ```
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if !self.is_empty() {
            write!(f, "0x")?;
            for b in self.0.iter().rev() {
                write!(f, "{:02x}", b)?;
            }
        }
        Ok(())
    }
}

impl FromStr for ConstantData {
    type Err = &'static str;

    /// Parse a hexadecimal string to `ConstantData`. This is the inverse of `Display::fmt`.
    ///
    /// ```
    /// use cranelift_codegen::ir::ConstantData;
    /// let c: ConstantData = "0x000102".parse().unwrap();
    /// assert_eq!(c.into_vec(), [2, 1, 0]);
    /// ```
    fn from_str(s: &str) -> Result<Self, &'static str> {
        if s.len() <= 2 || &s[0..2] != "0x" {
            return Err("Expected a hexadecimal string, e.g. 0x1234");
        }

        // clean and check the string
        let cleaned: Vec<u8> = s[2..]
            .as_bytes()
            .iter()
            .filter(|&&b| b as char != '_')
            .cloned()
            .collect(); // remove 0x prefix and any intervening _ characters

        if cleaned.is_empty() {
            Err("Hexadecimal string must have some digits")
        } else if cleaned.len() % 2 != 0 {
            Err("Hexadecimal string must have an even number of digits")
        } else if cleaned.len() > 32 {
            Err("Hexadecimal string has too many digits to fit in a 128-bit vector")
        } else {
            let mut buffer = Vec::with_capacity((s.len() - 2) / 2);
            for i in (0..cleaned.len()).step_by(2) {
                let pair = from_utf8(&cleaned[i..i + 2])
                    .or_else(|_| Err("Unable to parse hexadecimal pair as UTF-8"))?;
                let byte = u8::from_str_radix(pair, 16)
                    .or_else(|_| Err("Unable to parse as hexadecimal"))?;
                buffer.insert(0, byte);
            }
            Ok(Self(buffer))
        }
    }
}

/// Maintains the mapping between a constant handle (i.e.  [`Constant`](crate::ir::Constant)) and
/// its constant data (i.e.  [`ConstantData`](crate::ir::ConstantData)).
#[derive(Clone, PartialEq, Hash)]
#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
pub struct ConstantPool {
    /// This mapping maintains the insertion order as long as Constants are created with
    /// sequentially increasing integers.
    ///
    /// It is important that, by construction, no entry in that list gets removed. If that ever
    /// need to happen, don't forget to update the `Constant` generation scheme.
    handles_to_values: BTreeMap<Constant, ConstantData>,

    /// Mapping of hashed `ConstantData` to the index into the other hashmap.
    ///
    /// This allows for deduplication of entries into the `handles_to_values` mapping.
    values_to_handles: BTreeMap<ConstantData, Constant>,
}

impl ConstantPool {
    /// Create a new constant pool instance.
    pub fn new() -> Self {
        Self {
            handles_to_values: BTreeMap::new(),
            values_to_handles: BTreeMap::new(),
        }
    }

    /// Empty the constant pool of all data.
    pub fn clear(&mut self) {
        self.handles_to_values.clear();
        self.values_to_handles.clear();
    }

    /// Insert constant data into the pool, returning a handle for later referencing; when constant
    /// data is inserted that is a duplicate of previous constant data, the existing handle will be
    /// returned.
    pub fn insert(&mut self, constant_value: ConstantData) -> Constant {
        if let Some(cst) = self.values_to_handles.get(&constant_value) {
            return *cst;
        }

        let constant_handle = Constant::new(self.len());
        self.set(constant_handle, constant_value);
        constant_handle
    }

    /// Retrieve the constant data given a handle.
    pub fn get(&self, constant_handle: Constant) -> &ConstantData {
        assert!(self.handles_to_values.contains_key(&constant_handle));
        self.handles_to_values.get(&constant_handle).unwrap()
    }

    /// Link a constant handle to its value. This does not de-duplicate data but does avoid
    /// replacing any existing constant values. use `set` to tie a specific `const42` to its value;
    /// use `insert` to add a value and return the next available `const` entity.
    pub fn set(&mut self, constant_handle: Constant, constant_value: ConstantData) {
        let replaced = self
            .handles_to_values
            .insert(constant_handle, constant_value.clone());
        assert!(
            replaced.is_none(),
            "attempted to overwrite an existing constant {:?}: {:?} => {:?}",
            constant_handle,
            &constant_value,
            replaced.unwrap()
        );
        self.values_to_handles
            .insert(constant_value, constant_handle);
    }

    /// Iterate over the constants in insertion order.
    pub fn iter(&self) -> impl Iterator<Item = (&Constant, &ConstantData)> {
        self.handles_to_values.iter()
    }

    /// Iterate over mutable entries in the constant pool in insertion order.
    pub fn entries_mut(&mut self) -> impl Iterator<Item = &mut ConstantData> {
        self.handles_to_values.values_mut()
    }

    /// Return the number of constants in the pool.
    pub fn len(&self) -> usize {
        self.handles_to_values.len()
    }

    /// Return the combined size of all of the constant values in the pool.
    pub fn byte_size(&self) -> usize {
        self.handles_to_values.values().map(|c| c.len()).sum()
    }

src/verifier/mod.rs (line 1121)

    fn verify_constant_size(
        &self,
        inst: Inst,
        constant: Constant,
        errors: &mut VerifierErrors,
    ) -> VerifierStepResult<()> {
        let type_size = self.func.dfg.ctrl_typevar(inst).bytes() as usize;
        let constant_size = self.func.dfg.constants.get(constant).len();
        if type_size != constant_size {
            errors.fatal((
                inst,
                format!(
                    "The instruction expects {} to have a size of {} bytes but it has {}",
                    constant, type_size, constant_size
                ),
            ))
        } else {
            Ok(())
        }
    }

pub fn is_empty(&self) -> bool

Check if the constant contains any bytes.

Examples found in repository

src/ir/constant.rs (line 116)

    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if !self.is_empty() {
            write!(f, "0x")?;
            for b in self.0.iter().rev() {
                write!(f, "{:02x}", b)?;
            }
        }
        Ok(())
    }

pub fn as_slice(&self) -> &[u8]

Return the data as a slice.

Examples found in repository

src/machinst/vcode.rs (line 1536)

    pub fn as_slice(&self) -> &[u8] {
        match self {
            VCodeConstantData::Pool(_, d) | VCodeConstantData::Generated(d) => d.as_slice(),
            VCodeConstantData::WellKnown(d) => d,
            VCodeConstantData::U64(value) => &value[..],
        }
    }

pub fn into_vec(self) -> Vec<u8>

Convert the data to a vector.

pub fn iter(&self) -> Iter<'_, u8>

Iterate over the constant’s bytes.

Examples found in repository

src/isa/x64/lower/isle.rs (line 719)

    fn vconst_all_ones_or_all_zeros(&mut self, constant: Constant) -> Option<()> {
        let const_data = self.lower_ctx.get_constant_data(constant);
        if const_data.iter().all(|&b| b == 0 || b == 0xFF) {
            return Some(());
        }
        None
    }

pub fn append(self, bytes: impl IntoBytes) -> Self

Add new bytes to the constant data.

pub fn expand_to(self, expected_size: usize) -> Self

Expand the size of the constant data to expected_size number of bytes by adding zeroes in the high-order byte slots.

Trait Implementations

impl Clone for ConstantData

fn clone(&self) -> ConstantData

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ConstantData

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

Formats the value using the given formatter.

impl Default for ConstantData

fn default() -> ConstantData

Returns the “default value” for a type.

impl Display for ConstantData

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

Print the constant data in hexadecimal format, e.g. 0x000102030405060708090a0b0c0d0e0f. This function will flip the stored order of bytes–little-endian–to the more readable big-endian ordering.

use cranelift_codegen::ir::ConstantData;
let data = ConstantData::from([3, 2, 1, 0, 0].as_ref()); // note the little-endian order
assert_eq!(data.to_string(), "0x0000010203");

impl From<&[u8]> for ConstantData

fn from(v: &[u8]) -> Self

Converts to this type from the input type.

impl From<V128Imm> for ConstantData

fn from(v: V128Imm) -> Self

Converts to this type from the input type.

impl From<Vec<u8, Global>> for ConstantData

fn from(v: Vec<u8>) -> Self

Converts to this type from the input type.

impl FromIterator<u8> for ConstantData

fn from_iter<T: IntoIterator<Item = u8>>(iter: T) -> Self

Creates a value from an iterator.

impl FromStr for ConstantData

fn from_str(s: &str) -> Result<Self, &'static str>

Parse a hexadecimal string to ConstantData. This is the inverse of Display::fmt.

use cranelift_codegen::ir::ConstantData;
let c: ConstantData = "0x000102".parse().unwrap();
assert_eq!(c.into_vec(), [2, 1, 0]);

type Err = &'static str

The associated error which can be returned from parsing.

impl Hash for ConstantData

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,
    Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for ConstantData

fn cmp(&self, other: &ConstantData) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl PartialEq<ConstantData> for ConstantData

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd<ConstantData> for ConstantData

fn partial_cmp(&self, other: &ConstantData) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

This method tests less than (for self and other) and is used by the < operator.

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

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

This method tests greater than (for self and other) and is used by the > operator.

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for ConstantData

impl StructuralEq for ConstantData

impl StructuralPartialEq for ConstantData