Struct cranelift_codegen::settings::detail::Template

pub struct Template {
    pub name: &'static str,
    pub descriptors: &'static [Descriptor],
    pub enumerators: &'static [&'static str],
    pub hash_table: &'static [u16],
    pub defaults: &'static [u8],
    pub presets: &'static [(u8, u8)],
}

An instruction group template.

Fields

name: &'static str

Name of the instruction group.

descriptors: &'static [Descriptor]

List of setting descriptors.

enumerators: &'static [&'static str]

Union of all enumerators.

hash_table: &'static [u16]

Hash table of settings.

defaults: &'static [u8]

Default values.

presets: &'static [(u8, u8)]

Pairs of (mask, value) for presets.

Implementations

impl Template

pub fn enums(&self, last: u8, enumerators: u16) -> &[&'static str]

Get enumerators corresponding to a Details::Enum.

Examples found in repository

/opt/rustwide/target/x86_64-unknown-linux-gnu/debug/build/cranelift-codegen-0715cf9fa7730334/out/settings.rs (line 25)

    pub fn iter(&self) -> impl Iterator<Item = Value> {
        let mut bytes = [0; 9];
        bytes.copy_from_slice(&self.bytes[0..9]);
        DESCRIPTORS.iter().filter_map(move |d| {
            let values = match &d.detail {
                detail::Detail::Preset => return None,
                detail::Detail::Enum { last, enumerators } => Some(TEMPLATE.enums(*last, *enumerators)),
                _ => None
            };
            Some(Value{ name: d.name, detail: d.detail, values, value: bytes[d.offset as usize] })
        })
    }

src/settings.rs (line 176)

    pub fn iter(&self) -> impl Iterator<Item = Setting> {
        let template = self.template;

        template.descriptors.iter().map(move |d| {
            let (kind, values) = match d.detail {
                detail::Detail::Enum { last, enumerators } => {
                    let values = template.enums(last, enumerators);
                    (SettingKind::Enum, Some(values))
                }
                detail::Detail::Num => (SettingKind::Num, None),
                detail::Detail::Bool { .. } => (SettingKind::Bool, None),
                detail::Detail::Preset => (SettingKind::Preset, None),
            };

            Setting {
                name: d.name,
                description: d.description,
                kind,
                values,
            }
        })
    }

    /// Set the value of a single bit.
    fn set_bit(&mut self, offset: usize, bit: u8, value: bool) {
        let byte = &mut self.bytes[offset];
        let mask = 1 << bit;
        if value {
            *byte |= mask;
        } else {
            *byte &= !mask;
        }
    }

    /// Apply a preset. The argument is a slice of (mask, value) bytes.
    fn apply_preset(&mut self, values: &[(u8, u8)]) {
        for (byte, &(mask, value)) in self.bytes.iter_mut().zip(values) {
            *byte = (*byte & !mask) | value;
        }
    }

    /// Look up a descriptor by name.
    fn lookup(&self, name: &str) -> SetResult<(usize, detail::Detail)> {
        match probe(self.template, name, simple_hash(name)) {
            Err(_) => Err(SetError::BadName(name.to_string())),
            Ok(entry) => {
                let d = &self.template.descriptors[self.template.hash_table[entry] as usize];
                Ok((d.offset as usize, d.detail))
            }
        }
    }
}

fn parse_bool_value(value: &str) -> SetResult<bool> {
    match value {
        "true" | "on" | "yes" | "1" => Ok(true),
        "false" | "off" | "no" | "0" => Ok(false),
        _ => Err(SetError::BadValue("bool".to_string())),
    }
}

fn parse_enum_value(value: &str, choices: &[&str]) -> SetResult<u8> {
    match choices.iter().position(|&tag| tag == value) {
        Some(idx) => Ok(idx as u8),
        None => {
            // TODO: Use `join` instead of this code, once
            // https://github.com/rust-lang/rust/issues/27747 is resolved.
            let mut all_choices = String::new();
            let mut first = true;
            for choice in choices {
                if first {
                    first = false
                } else {
                    all_choices += ", ";
                }
                all_choices += choice;
            }
            Err(SetError::BadValue(format!("any among {}", all_choices)))
        }
    }
}

impl Configurable for Builder {
    fn enable(&mut self, name: &str) -> SetResult<()> {
        use self::detail::Detail;
        let (offset, detail) = self.lookup(name)?;
        match detail {
            Detail::Bool { bit } => {
                self.set_bit(offset, bit, true);
                Ok(())
            }
            Detail::Preset => {
                self.apply_preset(&self.template.presets[offset..]);
                Ok(())
            }
            _ => Err(SetError::BadType),
        }
    }

    fn set(&mut self, name: &str, value: &str) -> SetResult<()> {
        use self::detail::Detail;
        let (offset, detail) = self.lookup(name)?;
        match detail {
            Detail::Bool { bit } => {
                self.set_bit(offset, bit, parse_bool_value(value)?);
            }
            Detail::Num => {
                self.bytes[offset] = value
                    .parse()
                    .map_err(|_| SetError::BadValue("number".to_string()))?;
            }
            Detail::Enum { last, enumerators } => {
                self.bytes[offset] =
                    parse_enum_value(value, self.template.enums(last, enumerators))?;
            }
            Detail::Preset => return Err(SetError::BadName(name.to_string())),
        }
        Ok(())
    }
}

/// An error produced when changing a setting.
#[derive(Debug, PartialEq, Eq)]
pub enum SetError {
    /// No setting by this name exists.
    BadName(String),

    /// Type mismatch for setting (e.g., setting an enum setting as a bool).
    BadType,

    /// This is not a valid value for this setting.
    BadValue(String),
}

impl std::error::Error for SetError {}

impl fmt::Display for SetError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            SetError::BadName(name) => write!(f, "No existing setting named '{}'", name),
            SetError::BadType => {
                write!(f, "Trying to set a setting with the wrong type")
            }
            SetError::BadValue(value) => {
                write!(f, "Unexpected value for a setting, expected {}", value)
            }
        }
    }
}

/// A result returned when changing a setting.
pub type SetResult<T> = Result<T, SetError>;

/// A reference to just the boolean predicates of a settings object.
///
/// The settings objects themselves are generated and appear in the `isa/*/settings.rs` modules.
/// Each settings object provides a `predicate_view()` method that makes it possible to query
/// ISA predicates by number.
#[derive(Clone, Copy, Hash)]
pub struct PredicateView<'a>(&'a [u8]);

impl<'a> PredicateView<'a> {
    /// Create a new view of a precomputed predicate vector.
    ///
    /// See the `predicate_view()` method on the various `Flags` types defined for each ISA.
    pub fn new(bits: &'a [u8]) -> Self {
        PredicateView(bits)
    }

    /// Check a numbered predicate.
    pub fn test(self, p: usize) -> bool {
        self.0[p / 8] & (1 << (p % 8)) != 0
    }
}

/// Implementation details for generated code.
///
/// This module holds definitions that need to be public so the can be instantiated by generated
/// code in other modules.
pub mod detail {
    use crate::constant_hash;
    use core::fmt;
    use core::hash::Hash;

    /// An instruction group template.
    #[derive(Hash)]
    pub struct Template {
        /// Name of the instruction group.
        pub name: &'static str,
        /// List of setting descriptors.
        pub descriptors: &'static [Descriptor],
        /// Union of all enumerators.
        pub enumerators: &'static [&'static str],
        /// Hash table of settings.
        pub hash_table: &'static [u16],
        /// Default values.
        pub defaults: &'static [u8],
        /// Pairs of (mask, value) for presets.
        pub presets: &'static [(u8, u8)],
    }

    impl Template {
        /// Get enumerators corresponding to a `Details::Enum`.
        pub fn enums(&self, last: u8, enumerators: u16) -> &[&'static str] {
            let from = enumerators as usize;
            let len = usize::from(last) + 1;
            &self.enumerators[from..from + len]
        }

        /// Format a setting value as a TOML string. This is mostly for use by the generated
        /// `Display` implementation.
        pub fn format_toml_value(
            &self,
            detail: Detail,
            byte: u8,
            f: &mut fmt::Formatter,
        ) -> fmt::Result {
            match detail {
                Detail::Bool { bit } => write!(f, "{}", (byte & (1 << bit)) != 0),
                Detail::Num => write!(f, "{}", byte),
                Detail::Enum { last, enumerators } => {
                    if byte <= last {
                        let tags = self.enums(last, enumerators);
                        write!(f, "\"{}\"", tags[usize::from(byte)])
                    } else {
                        write!(f, "{}", byte)
                    }
                }
                // Presets aren't printed. They are reflected in the other settings.
                Detail::Preset { .. } => Ok(()),
            }
        }

pub fn format_toml_value(
    &self,
    detail: Detail,
    byte: u8,
    f: &mut Formatter<'_>
) -> Result

Format a setting value as a TOML string. This is mostly for use by the generated Display implementation.

Examples found in repository

/opt/rustwide/target/x86_64-unknown-linux-gnu/debug/build/cranelift-codegen-0715cf9fa7730334/out/settings.rs (line 828)

    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        writeln!(f, "[shared]")?;
        for d in &DESCRIPTORS {
            if !d.detail.is_preset() {
                write!(f, "{} = ", d.name)?;
                TEMPLATE.format_toml_value(d.detail, self.bytes[d.offset as usize], f)?;
                writeln!(f)?;
            }
        }
        Ok(())
    }

Trait Implementations

impl Hash for Template

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.