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Auto merge of #115220 - Zoxc:revive-gcx-ptr, r=oli-obk

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Add a `CurrentGcx` type to let the deadlock handler access `TyCtxt`

This brings back `GCX_PTR` (previously removed in https://github.com/rust-lang/rust/pull/74969) allowing the deadlock handler access to `GlobalCtxt`. This fixes https://github.com/rust-lang/rust/issues/111522.

r? `@cjgillot`
This commit is contained in:
bors 2024-03-28 14:00:08 +00:00
commit c5e7f45b62
5 changed files with 88 additions and 16 deletions
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13
compiler/rustc_interface/src/interface.rs
View File

@ -10,7 +10,9 @@
use rustc_errors::registry::Registry;
use rustc_errors::{DiagCtxt, ErrorGuaranteed};
use rustc_lint::LintStore;
use rustc_middle::ty;
use rustc_middle::ty::CurrentGcx;
use rustc_middle::util::Providers;
use rustc_parse::maybe_new_parser_from_source_str;
use rustc_query_impl::QueryCtxt;
@ -39,6 +41,7 @@ pub struct Compiler {
pub sess: Session,
pub codegen_backend: Box<dyn CodegenBackend>,
pub(crate) override_queries: Option<fn(&Session, &mut Providers)>,
pub(crate) current_gcx: CurrentGcx,
}
/// Converts strings provided as `--cfg [cfgspec]` into a `Cfg`.
@ -336,7 +339,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
util::run_in_thread_pool_with_globals(
config.opts.edition,
config.opts.unstable_opts.threads,
|| {
|current_gcx| {
crate::callbacks::setup_callbacks();
let early_dcx = EarlyDiagCtxt::new(config.opts.error_format);
@ -430,8 +433,12 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
}
sess.lint_store = Some(Lrc::new(lint_store));
let compiler =
Compiler { sess, codegen_backend, override_queries: config.override_queries };
let compiler = Compiler {
sess,
codegen_backend,
override_queries: config.override_queries,
current_gcx,
};
rustc_span::set_source_map(compiler.sess.psess.clone_source_map(), move || {
// There are two paths out of `f`.

1
compiler/rustc_interface/src/passes.rs
View File

@ -680,6 +680,7 @@ pub fn create_global_ctxt<'tcx>(
incremental,
),
providers.hooks,
compiler.current_gcx.clone(),
)
})
})

33
compiler/rustc_interface/src/util.rs
View File

@ -5,6 +5,7 @@
#[cfg(parallel_compiler)]
use rustc_data_structures::sync;
use rustc_metadata::{load_symbol_from_dylib, DylibError};
use rustc_middle::ty::CurrentGcx;
use rustc_parse::validate_attr;
use rustc_session as session;
use rustc_session::config::{Cfg, OutFileName, OutputFilenames, OutputTypes};
@ -64,7 +65,7 @@ fn init_stack_size() -> usize {
})
}
pub(crate) fn run_in_thread_with_globals<F: FnOnce() -> R + Send, R: Send>(
pub(crate) fn run_in_thread_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
edition: Edition,
f: F,
) -> R {
@ -82,7 +83,9 @@ pub(crate) fn run_in_thread_with_globals<F: FnOnce() -> R + Send, R: Send>(
// `unwrap` is ok here because `spawn_scoped` only panics if the thread
// name contains null bytes.
let r = builder
.spawn_scoped(s, move || rustc_span::create_session_globals_then(edition, f))
.spawn_scoped(s, move || {
rustc_span::create_session_globals_then(edition, || f(CurrentGcx::new()))
})
.unwrap()
.join();
@ -94,7 +97,7 @@ pub(crate) fn run_in_thread_with_globals<F: FnOnce() -> R + Send, R: Send>(
}
#[cfg(not(parallel_compiler))]
pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
edition: Edition,
_threads: usize,
f: F,
@ -103,7 +106,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
}
#[cfg(parallel_compiler)]
pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
edition: Edition,
threads: usize,
f: F,
@ -117,24 +120,34 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
let registry = sync::Registry::new(std::num::NonZero::new(threads).unwrap());
if !sync::is_dyn_thread_safe() {
return run_in_thread_with_globals(edition, || {
return run_in_thread_with_globals(edition, |current_gcx| {
// Register the thread for use with the `WorkerLocal` type.
registry.register();
f()
f(current_gcx)
});
}
let current_gcx = FromDyn::from(CurrentGcx::new());
let current_gcx2 = current_gcx.clone();
let builder = rayon::ThreadPoolBuilder::new()
.thread_name(|_| "rustc".to_string())
.acquire_thread_handler(jobserver::acquire_thread)
.release_thread_handler(jobserver::release_thread)
.num_threads(threads)
.deadlock_handler(|| {
.deadlock_handler(move || {
// On deadlock, creates a new thread and forwards information in thread
// locals to it. The new thread runs the deadlock handler.
let query_map =
FromDyn::from(tls::with(|tcx| QueryCtxt::new(tcx).collect_active_jobs()));
// Get a `GlobalCtxt` reference from `CurrentGcx` as we cannot rely on having a
// `TyCtxt` TLS reference here.
let query_map = current_gcx2.access(|gcx| {
tls::enter_context(&tls::ImplicitCtxt::new(gcx), || {
tls::with(|tcx| QueryCtxt::new(tcx).collect_active_jobs())
})
});
let query_map = FromDyn::from(query_map);
let registry = rayon_core::Registry::current();
thread::Builder::new()
.name("rustc query cycle handler".to_string())
@ -171,7 +184,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
})
},
// Run `f` on the first thread in the thread pool.
move |pool: &rayon::ThreadPool| pool.install(f),
move |pool: &rayon::ThreadPool| pool.install(|| f(current_gcx.into_inner())),
)
.unwrap()
})

53
compiler/rustc_middle/src/ty/context.rs
View File

@ -32,6 +32,7 @@
};
use crate::ty::{GenericArg, GenericArgs, GenericArgsRef};
use rustc_ast::{self as ast, attr};
use rustc_data_structures::defer;
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::intern::Interned;
@ -39,7 +40,7 @@
use rustc_data_structures::sharded::{IntoPointer, ShardedHashMap};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::steal::Steal;
use rustc_data_structures::sync::{self, FreezeReadGuard, Lock, Lrc, WorkerLocal};
use rustc_data_structures::sync::{self, FreezeReadGuard, Lock, Lrc, RwLock, WorkerLocal};
#[cfg(parallel_compiler)]
use rustc_data_structures::sync::{DynSend, DynSync};
use rustc_data_structures::unord::UnordSet;
@ -723,6 +724,8 @@ pub struct GlobalCtxt<'tcx> {
/// Stores memory for globals (statics/consts).
pub(crate) alloc_map: Lock<interpret::AllocMap<'tcx>>,
current_gcx: CurrentGcx,
}
impl<'tcx> GlobalCtxt<'tcx> {
@ -733,6 +736,19 @@ pub fn enter<'a: 'tcx, F, R>(&'a self, f: F) -> R
F: FnOnce(TyCtxt<'tcx>) -> R,
{
let icx = tls::ImplicitCtxt::new(self);
// Reset `current_gcx` to `None` when we exit.
let _on_drop = defer(move || {
*self.current_gcx.value.write() = None;
});
// Set this `GlobalCtxt` as the current one.
{
let mut guard = self.current_gcx.value.write();
assert!(guard.is_none(), "no `GlobalCtxt` is currently set");
*guard = Some(self as *const _ as *const ());
}
tls::enter_context(&icx, || f(icx.tcx))
}
@ -741,6 +757,39 @@ pub fn finish(&self) -> FileEncodeResult {
}
}
/// This is used to get a reference to a `GlobalCtxt` if one is available.
///
/// This is needed to allow the deadlock handler access to `GlobalCtxt` to look for query cycles.
/// It cannot use the `TLV` global because that's only guaranteed to be defined on the thread
/// creating the `GlobalCtxt`. Other threads have access to the `TLV` only inside Rayon jobs, but
/// the deadlock handler is not called inside such a job.
#[derive(Clone)]
pub struct CurrentGcx {
/// This stores a pointer to a `GlobalCtxt`. This is set to `Some` inside `GlobalCtxt::enter`
/// and reset to `None` when that function returns or unwinds.
value: Lrc<RwLock<Option<*const ()>>>,
}
#[cfg(parallel_compiler)]
unsafe impl DynSend for CurrentGcx {}
#[cfg(parallel_compiler)]
unsafe impl DynSync for CurrentGcx {}
impl CurrentGcx {
pub fn new() -> Self {
Self { value: Lrc::new(RwLock::new(None)) }
}
pub fn access<R>(&self, f: impl for<'tcx> FnOnce(&'tcx GlobalCtxt<'tcx>) -> R) -> R {
let read_guard = self.value.read();
let gcx: *const GlobalCtxt<'_> = read_guard.unwrap() as *const _;
// SAFETY: We hold the read lock for the `GlobalCtxt` pointer. That prevents
// `GlobalCtxt::enter` from returning as it would first acquire the write lock.
// This ensures the `GlobalCtxt` is live during `f`.
f(unsafe { &*gcx })
}
}
impl<'tcx> TyCtxt<'tcx> {
/// Expects a body and returns its codegen attributes.
///
@ -859,6 +908,7 @@ pub fn create_global_ctxt(
query_kinds: &'tcx [DepKindStruct<'tcx>],
query_system: QuerySystem<'tcx>,
hooks: crate::hooks::Providers,
current_gcx: CurrentGcx,
) -> GlobalCtxt<'tcx> {
let data_layout = s.target.parse_data_layout().unwrap_or_else(|err| {
s.dcx().emit_fatal(err);
@ -893,6 +943,7 @@ pub fn create_global_ctxt(
canonical_param_env_cache: Default::default(),
data_layout,
alloc_map: Lock::new(interpret::AllocMap::new()),
current_gcx,
}
}

4
compiler/rustc_middle/src/ty/mod.rs
View File

@ -87,8 +87,8 @@
Const, ConstData, ConstInt, ConstKind, Expr, ScalarInt, UnevaluatedConst, ValTree,
};
pub use self::context::{
tls, CtxtInterners, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt,
TyCtxtFeed,
tls, CtxtInterners, CurrentGcx, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift,
TyCtxt, TyCtxtFeed,
};
pub use self::instance::{Instance, InstanceDef, ShortInstance, UnusedGenericParams};
pub use self::list::List;