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Rollup merge of #116793 - WaffleLapkin:target_rules_the_backend, r=cjgillot

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Allow targets to override default codegen backend

Implements https://github.com/rust-lang/compiler-team/issues/670.
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Jubilee 2024-03-11 09:29:32 -07:00 • committed by GitHub
commit 86af4d25a5
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8 changed files with 117 additions and 59 deletions
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47
compiler/rustc_interface/src/util.rs
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@ -14,13 +14,14 @@ use rustc_session::{filesearch, output, Session};
use rustc_span::edit_distance::find_best_match_for_name;
use rustc_span::edition::Edition;
use rustc_span::symbol::{sym, Symbol};
use rustc_target::spec::Target;
use session::EarlyDiagCtxt;
use std::env;
use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::OnceLock;
use std::thread;
use std::{env, iter};
/// Function pointer type that constructs a new CodegenBackend.
pub type MakeBackendFn = fn() -> Box<dyn CodegenBackend>;
@ -195,21 +196,25 @@ fn load_backend_from_dylib(early_dcx: &EarlyDiagCtxt, path: &Path) -> MakeBacken
/// A name of `None` indicates that the default backend should be used.
pub fn get_codegen_backend(
early_dcx: &EarlyDiagCtxt,
maybe_sysroot: &Option<PathBuf>,
sysroot: &Path,
backend_name: Option<&str>,
target: &Target,
) -> Box<dyn CodegenBackend> {
static LOAD: OnceLock<unsafe fn() -> Box<dyn CodegenBackend>> = OnceLock::new();
let load = LOAD.get_or_init(|| {
let default_codegen_backend = option_env!("CFG_DEFAULT_CODEGEN_BACKEND").unwrap_or("llvm");
let backend = backend_name
.or(target.default_codegen_backend.as_deref())
.or(option_env!("CFG_DEFAULT_CODEGEN_BACKEND"))
.unwrap_or("llvm");
match backend_name.unwrap_or(default_codegen_backend) {
match backend {
filename if filename.contains('.') => {
load_backend_from_dylib(early_dcx, filename.as_ref())
}
#[cfg(feature = "llvm")]
"llvm" => rustc_codegen_llvm::LlvmCodegenBackend::new,
backend_name => get_codegen_sysroot(early_dcx, maybe_sysroot, backend_name),
backend_name => get_codegen_sysroot(early_dcx, sysroot, backend_name),
}
});
@ -244,7 +249,7 @@ fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
fn get_codegen_sysroot(
early_dcx: &EarlyDiagCtxt,
maybe_sysroot: &Option<PathBuf>,
sysroot: &Path,
backend_name: &str,
) -> MakeBackendFn {
// For now we only allow this function to be called once as it'll dlopen a
@ -261,28 +266,28 @@ fn get_codegen_sysroot(
let target = session::config::host_triple();
let sysroot_candidates = sysroot_candidates();
let sysroot = maybe_sysroot
.iter()
.chain(sysroot_candidates.iter())
let sysroot = iter::once(sysroot)
.chain(sysroot_candidates.iter().map(<_>::as_ref))
.map(|sysroot| {
filesearch::make_target_lib_path(sysroot, target).with_file_name("codegen-backends")
})
.find(|f| {
info!("codegen backend candidate: {}", f.display());
f.exists()
});
let sysroot = sysroot.unwrap_or_else(|| {
let candidates = sysroot_candidates
.iter()
.map(|p| p.display().to_string())
.collect::<Vec<_>>()
.join("\n* ");
let err = format!(
"failed to find a `codegen-backends` folder \
})
.unwrap_or_else(|| {
let candidates = sysroot_candidates
.iter()
.map(|p| p.display().to_string())
.collect::<Vec<_>>()
.join("\n* ");
let err = format!(
"failed to find a `codegen-backends` folder \
in the sysroot candidates:\n* {candidates}"
);
early_dcx.early_fatal(err);
});
);
early_dcx.early_fatal(err);
});
info!("probing {} for a codegen backend", sysroot.display());
let d = sysroot.read_dir().unwrap_or_else(|e| {