rustc_middle/middle/
exported_symbols.rs

1use rustc_hir::def_id::{DefId, LOCAL_CRATE};
2use rustc_macros::{Decodable, Encodable, HashStable, TyDecodable, TyEncodable};
3
4use crate::ty::{self, GenericArgsRef, Ty, TyCtxt};
5
6/// The SymbolExportLevel of a symbols specifies from which kinds of crates
7/// the symbol will be exported. `C` symbols will be exported from any
8/// kind of crate, including cdylibs which export very few things.
9/// `Rust` will only be exported if the crate produced is a Rust
10/// dylib.
11#[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)]
12pub enum SymbolExportLevel {
13    C,
14    Rust,
15}
16
17impl SymbolExportLevel {
18    pub fn is_below_threshold(self, threshold: SymbolExportLevel) -> bool {
19        threshold == SymbolExportLevel::Rust // export everything from Rust dylibs
20          || self == SymbolExportLevel::C
21    }
22}
23
24/// Kind of exported symbols.
25#[derive(Eq, PartialEq, Debug, Copy, Clone, Encodable, Decodable, HashStable, Hash)]
26pub enum SymbolExportKind {
27    Text,
28    Data,
29    Tls,
30}
31
32/// The `SymbolExportInfo` of a symbols specifies symbol-related information
33/// that is relevant to code generation and linking.
34///
35/// The difference between `used` and `rustc_std_internal_symbol` is that the
36/// former is exported by LTO while the latter isn't.
37#[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)]
38pub struct SymbolExportInfo {
39    pub level: SymbolExportLevel,
40    pub kind: SymbolExportKind,
41    /// Was the symbol marked as `#[used(compiler)]` or `#[used(linker)]`?
42    pub used: bool,
43    /// Was the symbol marked as `#[rustc_std_internal_symbol]`?
44    /// We also use this for externally implementable items.
45    pub rustc_std_internal_symbol: bool,
46}
47
48#[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)]
49pub enum ExportedSymbol<'tcx> {
50    NonGeneric(DefId),
51    Generic(DefId, GenericArgsRef<'tcx>),
52    DropGlue(Ty<'tcx>),
53    AsyncDropGlueCtorShim(Ty<'tcx>),
54    AsyncDropGlue(DefId, Ty<'tcx>),
55    ThreadLocalShim(DefId),
56    NoDefId(ty::SymbolName<'tcx>),
57}
58
59impl<'tcx> ExportedSymbol<'tcx> {
60    /// This is the symbol name of an instance if it is instantiated in the
61    /// local crate.
62    pub fn symbol_name_for_local_instance(&self, tcx: TyCtxt<'tcx>) -> ty::SymbolName<'tcx> {
63        match *self {
64            ExportedSymbol::NonGeneric(def_id) => tcx.symbol_name(ty::Instance::mono(tcx, def_id)),
65            ExportedSymbol::Generic(def_id, args) => {
66                tcx.symbol_name(ty::Instance::new_raw(def_id, args))
67            }
68            ExportedSymbol::DropGlue(ty) => {
69                tcx.symbol_name(ty::Instance::resolve_drop_in_place(tcx, ty))
70            }
71            ExportedSymbol::AsyncDropGlueCtorShim(ty) => {
72                tcx.symbol_name(ty::Instance::resolve_async_drop_in_place(tcx, ty))
73            }
74            ExportedSymbol::AsyncDropGlue(def_id, ty) => {
75                tcx.symbol_name(ty::Instance::resolve_async_drop_in_place_poll(tcx, def_id, ty))
76            }
77            ExportedSymbol::ThreadLocalShim(def_id) => tcx.symbol_name(ty::Instance {
78                def: ty::InstanceKind::ThreadLocalShim(def_id),
79                args: ty::GenericArgs::empty(),
80            }),
81            ExportedSymbol::NoDefId(symbol_name) => symbol_name,
82        }
83    }
84}
85
86pub fn metadata_symbol_name(tcx: TyCtxt<'_>) -> String {
87    format!(
88        "rust_metadata_{}_{:08x}",
89        tcx.crate_name(LOCAL_CRATE),
90        tcx.stable_crate_id(LOCAL_CRATE),
91    )
92}
rustc_middle/middle/exported_symbols.rs

rustc_middle/middle/
exported_symbols.rs
