diff options
Diffstat (limited to 'compiler/rustc_target/src/spec/crt_objects.rs')
| -rw-r--r-- | compiler/rustc_target/src/spec/crt_objects.rs | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/compiler/rustc_target/src/spec/crt_objects.rs b/compiler/rustc_target/src/spec/crt_objects.rs new file mode 100644 index 000000000..52ac3622e --- /dev/null +++ b/compiler/rustc_target/src/spec/crt_objects.rs @@ -0,0 +1,157 @@ +//! Object files providing support for basic runtime facilities and added to the produced binaries +//! at the start and at the end of linking. +//! +//! Table of CRT objects for popular toolchains. +//! The `crtx` ones are generally distributed with libc and the `begin/end` ones with gcc. +//! See <https://dev.gentoo.org/~vapier/crt.txt> for some more details. +//! +//! | Pre-link CRT objects | glibc | musl | bionic | mingw | wasi | +//! |----------------------|------------------------|------------------------|------------------|-------------------|--------------| +//! | dynamic-nopic-exe | crt1, crti, crtbegin | crt1, crti, crtbegin | crtbegin_dynamic | crt2, crtbegin | crt1 | +//! | dynamic-pic-exe | Scrt1, crti, crtbeginS | Scrt1, crti, crtbeginS | crtbegin_dynamic | crt2, crtbegin | crt1 | +//! | static-nopic-exe | crt1, crti, crtbeginT | crt1, crti, crtbegin | crtbegin_static | crt2, crtbegin | crt1 | +//! | static-pic-exe | rcrt1, crti, crtbeginS | rcrt1, crti, crtbeginS | crtbegin_dynamic | crt2, crtbegin | crt1 | +//! | dynamic-dylib | crti, crtbeginS | crti, crtbeginS | crtbegin_so | dllcrt2, crtbegin | - | +//! | static-dylib (gcc) | crti, crtbeginT | crti, crtbeginS | crtbegin_so | dllcrt2, crtbegin | - | +//! | static-dylib (clang) | crti, crtbeginT | N/A | crtbegin_static | dllcrt2, crtbegin | - | +//! | wasi-reactor-exe | N/A | N/A | N/A | N/A | crt1-reactor | +//! +//! | Post-link CRT objects | glibc | musl | bionic | mingw | wasi | +//! |-----------------------|---------------|---------------|----------------|--------|------| +//! | dynamic-nopic-exe | crtend, crtn | crtend, crtn | crtend_android | crtend | - | +//! | dynamic-pic-exe | crtendS, crtn | crtendS, crtn | crtend_android | crtend | - | +//! | static-nopic-exe | crtend, crtn | crtend, crtn | crtend_android | crtend | - | +//! | static-pic-exe | crtendS, crtn | crtendS, crtn | crtend_android | crtend | - | +//! | dynamic-dylib | crtendS, crtn | crtendS, crtn | crtend_so | crtend | - | +//! | static-dylib (gcc) | crtend, crtn | crtendS, crtn | crtend_so | crtend | - | +//! | static-dylib (clang) | crtendS, crtn | N/A | crtend_so | crtend | - | +//! +//! Use cases for rustc linking the CRT objects explicitly: +//! - rustc needs to add its own Rust-specific objects (mingw is the example) +//! - gcc wrapper cannot be used for some reason and linker like ld or lld is used directly. +//! - gcc wrapper pulls wrong CRT objects (e.g. from glibc when we are targeting musl). +//! +//! In general it is preferable to rely on the target's native toolchain to pull the objects. +//! However, for some targets (musl, mingw) rustc historically provides a more self-contained +//! installation not requiring users to install the native target's toolchain. +//! In that case rustc distributes the objects as a part of the target's Rust toolchain +//! and falls back to linking with them manually. +//! Unlike native toolchains, rustc only currently adds the libc's objects during linking, +//! but not gcc's. As a result rustc cannot link with C++ static libraries (#36710) +//! when linking in self-contained mode. + +use crate::json::{Json, ToJson}; +use crate::spec::LinkOutputKind; +use std::borrow::Cow; +use std::collections::BTreeMap; +use std::str::FromStr; + +pub type CrtObjects = BTreeMap<LinkOutputKind, Vec<Cow<'static, str>>>; + +pub(super) fn new(obj_table: &[(LinkOutputKind, &[&'static str])]) -> CrtObjects { + obj_table.iter().map(|(z, k)| (*z, k.iter().map(|b| (*b).into()).collect())).collect() +} + +pub(super) fn all(obj: &'static str) -> CrtObjects { + new(&[ + (LinkOutputKind::DynamicNoPicExe, &[obj]), + (LinkOutputKind::DynamicPicExe, &[obj]), + (LinkOutputKind::StaticNoPicExe, &[obj]), + (LinkOutputKind::StaticPicExe, &[obj]), + (LinkOutputKind::DynamicDylib, &[obj]), + (LinkOutputKind::StaticDylib, &[obj]), + ]) +} + +pub(super) fn pre_musl_fallback() -> CrtObjects { + new(&[ + (LinkOutputKind::DynamicNoPicExe, &["crt1.o", "crti.o", "crtbegin.o"]), + (LinkOutputKind::DynamicPicExe, &["Scrt1.o", "crti.o", "crtbeginS.o"]), + (LinkOutputKind::StaticNoPicExe, &["crt1.o", "crti.o", "crtbegin.o"]), + (LinkOutputKind::StaticPicExe, &["rcrt1.o", "crti.o", "crtbeginS.o"]), + (LinkOutputKind::DynamicDylib, &["crti.o", "crtbeginS.o"]), + (LinkOutputKind::StaticDylib, &["crti.o", "crtbeginS.o"]), + ]) +} + +pub(super) fn post_musl_fallback() -> CrtObjects { + new(&[ + (LinkOutputKind::DynamicNoPicExe, &["crtend.o", "crtn.o"]), + (LinkOutputKind::DynamicPicExe, &["crtendS.o", "crtn.o"]), + (LinkOutputKind::StaticNoPicExe, &["crtend.o", "crtn.o"]), + (LinkOutputKind::StaticPicExe, &["crtendS.o", "crtn.o"]), + (LinkOutputKind::DynamicDylib, &["crtendS.o", "crtn.o"]), + (LinkOutputKind::StaticDylib, &["crtendS.o", "crtn.o"]), + ]) +} + +pub(super) fn pre_mingw_fallback() -> CrtObjects { + new(&[ + (LinkOutputKind::DynamicNoPicExe, &["crt2.o", "rsbegin.o"]), + (LinkOutputKind::DynamicPicExe, &["crt2.o", "rsbegin.o"]), + (LinkOutputKind::StaticNoPicExe, &["crt2.o", "rsbegin.o"]), + (LinkOutputKind::StaticPicExe, &["crt2.o", "rsbegin.o"]), + (LinkOutputKind::DynamicDylib, &["dllcrt2.o", "rsbegin.o"]), + (LinkOutputKind::StaticDylib, &["dllcrt2.o", "rsbegin.o"]), + ]) +} + +pub(super) fn post_mingw_fallback() -> CrtObjects { + all("rsend.o") +} + +pub(super) fn pre_mingw() -> CrtObjects { + all("rsbegin.o") +} + +pub(super) fn post_mingw() -> CrtObjects { + all("rsend.o") +} + +pub(super) fn pre_wasi_fallback() -> CrtObjects { + // Use crt1-command.o instead of crt1.o to enable support for new-style + // commands. See https://reviews.llvm.org/D81689 for more info. + new(&[ + (LinkOutputKind::DynamicNoPicExe, &["crt1-command.o"]), + (LinkOutputKind::DynamicPicExe, &["crt1-command.o"]), + (LinkOutputKind::StaticNoPicExe, &["crt1-command.o"]), + (LinkOutputKind::StaticPicExe, &["crt1-command.o"]), + (LinkOutputKind::WasiReactorExe, &["crt1-reactor.o"]), + ]) +} + +pub(super) fn post_wasi_fallback() -> CrtObjects { + new(&[]) +} + +/// Which logic to use to determine whether to fall back to the "self-contained" mode or not. +#[derive(Clone, Copy, PartialEq, Hash, Debug)] +pub enum CrtObjectsFallback { + Musl, + Mingw, + Wasm, +} + +impl FromStr for CrtObjectsFallback { + type Err = (); + + fn from_str(s: &str) -> Result<CrtObjectsFallback, ()> { + Ok(match s { + "musl" => CrtObjectsFallback::Musl, + "mingw" => CrtObjectsFallback::Mingw, + "wasm" => CrtObjectsFallback::Wasm, + _ => return Err(()), + }) + } +} + +impl ToJson for CrtObjectsFallback { + fn to_json(&self) -> Json { + match *self { + CrtObjectsFallback::Musl => "musl", + CrtObjectsFallback::Mingw => "mingw", + CrtObjectsFallback::Wasm => "wasm", + } + .to_json() + } +} |