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use crate::abi::FnAbi;
use crate::crate_def::CrateDef;
use crate::mir::Body;
use crate::ty::{Allocation, ClosureDef, ClosureKind, FnDef, GenericArgs, IndexedVal, Ty};
use crate::{with, CrateItem, DefId, Error, ItemKind, Opaque, Symbol};
use std::fmt::{Debug, Formatter};
use std::io;
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub enum MonoItem {
Fn(Instance),
Static(StaticDef),
GlobalAsm(Opaque),
}
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
pub struct Instance {
/// The type of instance.
pub kind: InstanceKind,
/// An ID used to get the instance definition from the compiler.
/// Do not use this field directly.
pub def: InstanceDef,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub enum InstanceKind {
/// A user defined item.
Item,
/// A compiler intrinsic function.
Intrinsic,
/// A virtual function definition stored in a VTable.
/// The `idx` field indicates the position in the VTable for this instance.
Virtual { idx: usize },
/// A compiler generated shim.
Shim,
}
impl Instance {
/// Get the arguments this instance was instantiated with.
pub fn args(&self) -> GenericArgs {
with(|cx| cx.instance_args(self.def))
}
/// Get the body of an Instance.
///
/// The body will be eagerly monomorphized and all constants will already be evaluated.
///
/// This method will return the intrinsic fallback body if one was defined.
pub fn body(&self) -> Option<Body> {
with(|context| context.instance_body(self.def))
}
/// Check whether this instance has a body available.
///
/// For intrinsics with fallback body, this will return `true`. It is up to the user to decide
/// whether to specialize the intrinsic or to use its fallback body.
///
/// For more information on fallback body, see <https://github.com/rust-lang/rust/issues/93145>.
///
/// This call is much cheaper than `instance.body().is_some()`, since it doesn't try to build
/// the StableMIR body.
pub fn has_body(&self) -> bool {
with(|cx| cx.has_body(self.def.def_id()))
}
pub fn is_foreign_item(&self) -> bool {
with(|cx| cx.is_foreign_item(self.def.def_id()))
}
/// Get the instance type with generic instantiations applied and lifetimes erased.
pub fn ty(&self) -> Ty {
with(|context| context.instance_ty(self.def))
}
/// Retrieve information about this instance binary interface.
pub fn fn_abi(&self) -> Result<FnAbi, Error> {
with(|cx| cx.instance_abi(self.def))
}
/// Retrieve the instance's mangled name used for calling the given instance.
///
/// This will also look up the correct name of instances from upstream crates.
pub fn mangled_name(&self) -> Symbol {
with(|context| context.instance_mangled_name(self.def))
}
/// Retrieve the instance name for diagnostic messages.
///
/// This will return the specialized name, e.g., `std::vec::Vec<u8>::new`.
pub fn name(&self) -> Symbol {
with(|context| context.instance_name(self.def, false))
}
/// Return a trimmed name of the given instance including its args.
///
/// If a symbol name can only be imported from one place for a type, and as
/// long as it was not glob-imported anywhere in the current crate, we trim its
/// path and print only the name.
pub fn trimmed_name(&self) -> Symbol {
with(|context| context.instance_name(self.def, true))
}
/// Retrieve the plain intrinsic name of an instance if it's an intrinsic.
///
/// The plain name does not include type arguments (as `trimmed_name` does),
/// which is more convenient to match with intrinsic symbols.
pub fn intrinsic_name(&self) -> Option<Symbol> {
match self.kind {
InstanceKind::Intrinsic => {
Some(with(|context| context.intrinsic(self.def.def_id()).unwrap().fn_name()))
}
InstanceKind::Item | InstanceKind::Virtual { .. } | InstanceKind::Shim => None,
}
}
/// Resolve an instance starting from a function definition and generic arguments.
pub fn resolve(def: FnDef, args: &GenericArgs) -> Result<Instance, crate::Error> {
with(|context| {
context.resolve_instance(def, args).ok_or_else(|| {
crate::Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`"))
})
})
}
/// Resolve the drop in place for a given type.
pub fn resolve_drop_in_place(ty: Ty) -> Instance {
with(|cx| cx.resolve_drop_in_place(ty))
}
/// Resolve an instance for a given function pointer.
pub fn resolve_for_fn_ptr(def: FnDef, args: &GenericArgs) -> Result<Instance, crate::Error> {
with(|context| {
context.resolve_for_fn_ptr(def, args).ok_or_else(|| {
crate::Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`"))
})
})
}
/// Resolve a closure with the expected kind.
pub fn resolve_closure(
def: ClosureDef,
args: &GenericArgs,
kind: ClosureKind,
) -> Result<Instance, crate::Error> {
with(|context| {
context.resolve_closure(def, args, kind).ok_or_else(|| {
crate::Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`"))
})
})
}
/// Check whether this instance is an empty shim.
///
/// Allow users to check if this shim can be ignored when called directly.
///
/// We have decided not to export different types of Shims to StableMIR users, however, this
/// is a query that can be very helpful for users when processing DropGlue.
///
/// When generating code for a Drop terminator, users can ignore an empty drop glue.
/// These shims are only needed to generate a valid Drop call done via VTable.
pub fn is_empty_shim(&self) -> bool {
self.kind == InstanceKind::Shim
&& with(|cx| {
cx.is_empty_drop_shim(self.def) || cx.is_empty_async_drop_ctor_shim(self.def)
})
}
/// Try to constant evaluate the instance into a constant with the given type.
///
/// This can be used to retrieve a constant that represents an intrinsic return such as
/// `type_id`.
pub fn try_const_eval(&self, const_ty: Ty) -> Result<Allocation, Error> {
with(|cx| cx.eval_instance(self.def, const_ty))
}
/// Emit the body of this instance if it has one.
pub fn emit_mir<W: io::Write>(&self, w: &mut W) -> io::Result<()> {
if let Some(body) = self.body() { body.dump(w, &self.name()) } else { Ok(()) }
}
}
impl Debug for Instance {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
f.debug_struct("Instance")
.field("kind", &self.kind)
.field("def", &self.mangled_name())
.field("args", &self.args())
.finish()
}
}
/// Try to convert a crate item into an instance.
/// The item cannot be generic in order to be converted into an instance.
impl TryFrom<CrateItem> for Instance {
type Error = crate::Error;
fn try_from(item: CrateItem) -> Result<Self, Self::Error> {
with(|context| {
let def_id = item.def_id();
if !context.requires_monomorphization(def_id) {
Ok(context.mono_instance(def_id))
} else {
Err(Error::new("Item requires monomorphization".to_string()))
}
})
}
}
/// Try to convert an instance into a crate item.
/// Only user defined instances can be converted.
impl TryFrom<Instance> for CrateItem {
type Error = crate::Error;
fn try_from(value: Instance) -> Result<Self, Self::Error> {
with(|context| {
if value.kind == InstanceKind::Item && context.has_body(value.def.def_id()) {
Ok(CrateItem(context.instance_def_id(value.def)))
} else {
Err(Error::new(format!("Item kind `{:?}` cannot be converted", value.kind)))
}
})
}
}
impl From<Instance> for MonoItem {
fn from(value: Instance) -> Self {
MonoItem::Fn(value)
}
}
impl From<StaticDef> for MonoItem {
fn from(value: StaticDef) -> Self {
MonoItem::Static(value)
}
}
impl From<StaticDef> for CrateItem {
fn from(value: StaticDef) -> Self {
CrateItem(value.0)
}
}
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct InstanceDef(usize);
impl CrateDef for InstanceDef {
fn def_id(&self) -> DefId {
with(|context| context.instance_def_id(*self))
}
}
crate_def! {
/// Holds information about a static variable definition.
pub StaticDef;
}
impl TryFrom<CrateItem> for StaticDef {
type Error = crate::Error;
fn try_from(value: CrateItem) -> Result<Self, Self::Error> {
if matches!(value.kind(), ItemKind::Static) {
Ok(StaticDef(value.0))
} else {
Err(Error::new(format!("Expected a static item, but found: {value:?}")))
}
}
}
impl TryFrom<Instance> for StaticDef {
type Error = crate::Error;
fn try_from(value: Instance) -> Result<Self, Self::Error> {
StaticDef::try_from(CrateItem::try_from(value)?)
}
}
impl From<StaticDef> for Instance {
fn from(value: StaticDef) -> Self {
// A static definition should always be convertible to an instance.
with(|cx| cx.mono_instance(value.def_id()))
}
}
impl StaticDef {
/// Return the type of this static definition.
pub fn ty(&self) -> Ty {
with(|cx| cx.def_ty(self.0))
}
/// Evaluate a static's initializer, returning the allocation of the initializer's memory.
pub fn eval_initializer(&self) -> Result<Allocation, Error> {
with(|cx| cx.eval_static_initializer(*self))
}
}
impl IndexedVal for InstanceDef {
fn to_val(index: usize) -> Self {
InstanceDef(index)
}
fn to_index(&self) -> usize {
self.0
}
}