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Remove GcxPtr
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Zoxc committed Oct 1, 2023
1 parent b555ae8 commit 9c39555
Showing 1 changed file with 25 additions and 29 deletions.
54 changes: 25 additions & 29 deletions compiler/rustc_middle/src/ty/context.rs
Original file line number Diff line number Diff line change
Expand Up @@ -40,9 +40,9 @@ use rustc_data_structures::profiling::SelfProfilerRef;
use rustc_data_structures::sharded::{IntoPointer, ShardedHashMap};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::steal::Steal;
#[cfg(parallel_compiler)]
use rustc_data_structures::sync::DynSend;
use rustc_data_structures::sync::{self, FreezeReadGuard, Lock, Lrc, RwLock, WorkerLocal};
use rustc_data_structures::sync::{
self, DynSend, DynSync, FreezeReadGuard, Lock, Lrc, RwLock, WorkerLocal,
};
use rustc_data_structures::unord::UnordSet;
use rustc_errors::{
DecorateLint, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, MultiSpan,
Expand Down Expand Up @@ -542,7 +542,7 @@ pub struct GlobalCtxt<'tcx> {
///
/// FIXME(Centril): consider `dyn LintStoreMarker` once
/// we can upcast to `Any` for some additional type safety.
pub lint_store: Lrc<dyn Any + sync::DynSync + sync::DynSend>,
pub lint_store: Lrc<dyn Any + DynSync + DynSend>,

pub dep_graph: DepGraph,

Expand Down Expand Up @@ -601,32 +601,22 @@ impl<'tcx> GlobalCtxt<'tcx> {
{
let icx = tls::ImplicitCtxt::new(self);

let gcx_ptr =
GcxPtr { value: Lrc::new(RwLock::new(Some(icx.tcx.gcx as *const _ as *const ()))) };

// Reset `gcx_ptr` to `None` when we exit.
let gcx_ptr_ = gcx_ptr.clone();
// Reset `current_gcx` to `None` when we exit.
let _on_drop = defer(move || {
*gcx_ptr_.value.write() = None;
*self.current_gcx.value.write() = None;
});

// Set this `GlobalCtxt` as the current one.
*self.current_gcx.value.lock() = Some(gcx_ptr);
{
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))
}
}

/// This stores a pointer to a `GlobalCtxt`. When the `GlobalCtxt` is no longer available the lock
/// will be set to `None`.
#[derive(Clone)]
struct GcxPtr {
value: Lrc<RwLock<Option<*const ()>>>,
}

#[cfg(parallel_compiler)]
unsafe impl DynSend for GcxPtr {}

/// 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.
Expand All @@ -635,21 +625,27 @@ unsafe impl DynSend for GcxPtr {}
/// the deadlock handler is not called inside such a job.
#[derive(Clone)]
pub struct CurrentGcx {
value: Lrc<Lock<Option<GcxPtr>>>,
/// 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(Lock::new(None)) }
Self { value: Lrc::new(RwLock::new(None)) }
}

pub fn access<R>(&self, f: impl for<'tcx> FnOnce(&'tcx GlobalCtxt<'tcx>) -> R) -> R {
let gcx_ptr = self.value.lock().clone().unwrap();
let read_guard = gcx_ptr.value.read();
let read_guard = self.value.read();
let gcx: *const GlobalCtxt<'_> = read_guard.unwrap() as *const _;
// SAFETY: We hold the read lock for `GcxPtr`. That prevents `GlobalCtxt::enter` from
// returning as it would first acquire the write lock. This ensures the `GlobalCtxt` is
// live during `f`.
// 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 })
}
}
Expand Down Expand Up @@ -755,7 +751,7 @@ impl<'tcx> TyCtxt<'tcx> {
s: &'tcx Session,
crate_types: Vec<CrateType>,
stable_crate_id: StableCrateId,
lint_store: Lrc<dyn Any + sync::DynSend + sync::DynSync>,
lint_store: Lrc<dyn Any + DynSend + DynSync>,
arena: &'tcx WorkerLocal<Arena<'tcx>>,
hir_arena: &'tcx WorkerLocal<hir::Arena<'tcx>>,
untracked: Untracked,
Expand Down

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