Rollup merge of #107150 - Nilstrieb:thread-local-cleanups, r=cjgillot

`ty::tls` cleanups

Pull it out into a separate file, make the conditional compilation more obvious and give the internal functions better names.

Pulled out of #106311

r? cjgillot

Author: matthiaskrgr

compiler/rustc_middle/src/lib.rs

@@ -43,6 +43,7 @@
 #![feature(min_specialization)]
 #![feature(trusted_len)]
 #![feature(type_alias_impl_trait)]
+#![feature(strict_provenance)]
 #![feature(associated_type_bounds)]
 #![feature(rustc_attrs)]
 #![feature(control_flow_enum)]

compiler/rustc_middle/src/ty/context.rs

@@ -2,6 +2,8 @@
 
 #![allow(rustc::usage_of_ty_tykind)]
 
+pub mod tls;
+
 use crate::arena::Arena;
 use crate::dep_graph::{DepGraph, DepKindStruct};
 use crate::infer::canonical::{CanonicalVarInfo, CanonicalVarInfos};
@@ -1212,178 +1214,6 @@ CloneLiftImpls! { for<'tcx> {
     Constness, traits::WellFormedLoc, ImplPolarity, crate::mir::ReturnConstraint,
 } }
 
-pub mod tls {
-    use super::{ptr_eq, GlobalCtxt, TyCtxt};
-
-    use crate::dep_graph::TaskDepsRef;
-    use crate::ty::query;
-    use rustc_data_structures::sync::{self, Lock};
-    use rustc_errors::Diagnostic;
-    use std::mem;
-    use thin_vec::ThinVec;
-
-    #[cfg(not(parallel_compiler))]
-    use std::cell::Cell;
-
-    #[cfg(parallel_compiler)]
-    use rustc_rayon_core as rayon_core;
-
-    /// This is the implicit state of rustc. It contains the current
-    /// `TyCtxt` and query. It is updated when creating a local interner or
-    /// executing a new query. Whenever there's a `TyCtxt` value available
-    /// you should also have access to an `ImplicitCtxt` through the functions
-    /// in this module.
-    #[derive(Clone)]
-    pub struct ImplicitCtxt<'a, 'tcx> {
-        /// The current `TyCtxt`.
-        pub tcx: TyCtxt<'tcx>,
-
-        /// The current query job, if any. This is updated by `JobOwner::start` in
-        /// `ty::query::plumbing` when executing a query.
-        pub query: Option<query::QueryJobId>,
-
-        /// Where to store diagnostics for the current query job, if any.
-        /// This is updated by `JobOwner::start` in `ty::query::plumbing` when executing a query.
-        pub diagnostics: Option<&'a Lock<ThinVec<Diagnostic>>>,
-
-        /// Used to prevent queries from calling too deeply.
-        pub query_depth: usize,
-
-        /// The current dep graph task. This is used to add dependencies to queries
-        /// when executing them.
-        pub task_deps: TaskDepsRef<'a>,
-    }
-
-    impl<'a, 'tcx> ImplicitCtxt<'a, 'tcx> {
-        pub fn new(gcx: &'tcx GlobalCtxt<'tcx>) -> Self {
-            let tcx = TyCtxt { gcx };
-            ImplicitCtxt {
-                tcx,
-                query: None,
-                diagnostics: None,
-                query_depth: 0,
-                task_deps: TaskDepsRef::Ignore,
-            }
-        }
-    }
-
-    /// Sets Rayon's thread-local variable, which is preserved for Rayon jobs
-    /// to `value` during the call to `f`. It is restored to its previous value after.
-    /// This is used to set the pointer to the new `ImplicitCtxt`.
-    #[cfg(parallel_compiler)]
-    #[inline]
-    fn set_tlv<F: FnOnce() -> R, R>(value: usize, f: F) -> R {
-        rayon_core::tlv::with(value, f)
-    }
-
-    /// Gets Rayon's thread-local variable, which is preserved for Rayon jobs.
-    /// This is used to get the pointer to the current `ImplicitCtxt`.
-    #[cfg(parallel_compiler)]
-    #[inline]
-    pub fn get_tlv() -> usize {
-        rayon_core::tlv::get()
-    }
-
-    #[cfg(not(parallel_compiler))]
-    thread_local! {
-        /// A thread local variable that stores a pointer to the current `ImplicitCtxt`.
-        static TLV: Cell<usize> = const { Cell::new(0) };
-    }
-
-    /// Sets TLV to `value` during the call to `f`.
-    /// It is restored to its previous value after.
-    /// This is used to set the pointer to the new `ImplicitCtxt`.
-    #[cfg(not(parallel_compiler))]
-    #[inline]
-    fn set_tlv<F: FnOnce() -> R, R>(value: usize, f: F) -> R {
-        let old = get_tlv();
-        let _reset = rustc_data_structures::OnDrop(move || TLV.with(|tlv| tlv.set(old)));
-        TLV.with(|tlv| tlv.set(value));
-        f()
-    }
-
-    /// Gets the pointer to the current `ImplicitCtxt`.
-    #[cfg(not(parallel_compiler))]
-    #[inline]
-    fn get_tlv() -> usize {
-        TLV.with(|tlv| tlv.get())
-    }
-
-    /// Sets `context` as the new current `ImplicitCtxt` for the duration of the function `f`.
-    #[inline]
-    pub fn enter_context<'a, 'tcx, F, R>(context: &ImplicitCtxt<'a, 'tcx>, f: F) -> R
-    where
-        F: FnOnce(&ImplicitCtxt<'a, 'tcx>) -> R,
-    {
-        set_tlv(context as *const _ as usize, || f(&context))
-    }
-
-    /// Allows access to the current `ImplicitCtxt` in a closure if one is available.
-    #[inline]
-    pub fn with_context_opt<F, R>(f: F) -> R
-    where
-        F: for<'a, 'tcx> FnOnce(Option<&ImplicitCtxt<'a, 'tcx>>) -> R,
-    {
-        let context = get_tlv();
-        if context == 0 {
-            f(None)
-        } else {
-            // We could get an `ImplicitCtxt` pointer from another thread.
-            // Ensure that `ImplicitCtxt` is `Sync`.
-            sync::assert_sync::<ImplicitCtxt<'_, '_>>();
-
-            unsafe { f(Some(&*(context as *const ImplicitCtxt<'_, '_>))) }
-        }
-    }
-
-    /// Allows access to the current `ImplicitCtxt`.
-    /// Panics if there is no `ImplicitCtxt` available.
-    #[inline]
-    pub fn with_context<F, R>(f: F) -> R
-    where
-        F: for<'a, 'tcx> FnOnce(&ImplicitCtxt<'a, 'tcx>) -> R,
-    {
-        with_context_opt(|opt_context| f(opt_context.expect("no ImplicitCtxt stored in tls")))
-    }
-
-    /// Allows access to the current `ImplicitCtxt` whose tcx field is the same as the tcx argument
-    /// passed in. This means the closure is given an `ImplicitCtxt` with the same `'tcx` lifetime
-    /// as the `TyCtxt` passed in.
-    /// This will panic if you pass it a `TyCtxt` which is different from the current
-    /// `ImplicitCtxt`'s `tcx` field.
-    #[inline]
-    pub fn with_related_context<'tcx, F, R>(tcx: TyCtxt<'tcx>, f: F) -> R
-    where
-        F: FnOnce(&ImplicitCtxt<'_, 'tcx>) -> R,
-    {
-        with_context(|context| unsafe {
-            assert!(ptr_eq(context.tcx.gcx, tcx.gcx));
-            let context: &ImplicitCtxt<'_, '_> = mem::transmute(context);
-            f(context)
-        })
-    }
-
-    /// Allows access to the `TyCtxt` in the current `ImplicitCtxt`.
-    /// Panics if there is no `ImplicitCtxt` available.
-    #[inline]
-    pub fn with<F, R>(f: F) -> R
-    where
-        F: for<'tcx> FnOnce(TyCtxt<'tcx>) -> R,
-    {
-        with_context(|context| f(context.tcx))
-    }
-
-    /// Allows access to the `TyCtxt` in the current `ImplicitCtxt`.
-    /// The closure is passed None if there is no `ImplicitCtxt` available.
-    #[inline]
-    pub fn with_opt<F, R>(f: F) -> R
-    where
-        F: for<'tcx> FnOnce(Option<TyCtxt<'tcx>>) -> R,
-    {
-        with_context_opt(|opt_context| f(opt_context.map(|context| context.tcx)))
-    }
-}
-
 macro_rules! sty_debug_print {
     ($fmt: expr, $ctxt: expr, $($variant: ident),*) => {{
         // Curious inner module to allow variant names to be used as
@@ -2416,12 +2246,6 @@ pub struct DeducedParamAttrs {
     pub read_only: bool,
 }
 
-// We are comparing types with different invariant lifetimes, so `ptr::eq`
-// won't work for us.
-fn ptr_eq<T, U>(t: *const T, u: *const U) -> bool {
-    t as *const () == u as *const ()
-}
-
 pub fn provide(providers: &mut ty::query::Providers) {
     providers.module_reexports =
         |tcx, id| tcx.resolutions(()).reexport_map.get(&id).map(|v| &v[..]);

compiler/rustc_middle/src/ty/context/tls.rs

@@ -0,0 +1,187 @@
+use super::{GlobalCtxt, TyCtxt};
+
+use crate::dep_graph::TaskDepsRef;
+use crate::ty::query;
+use rustc_data_structures::sync::{self, Lock};
+use rustc_errors::Diagnostic;
+use std::mem;
+use std::ptr;
+use thin_vec::ThinVec;
+
+/// This is the implicit state of rustc. It contains the current
+/// `TyCtxt` and query. It is updated when creating a local interner or
+/// executing a new query. Whenever there's a `TyCtxt` value available
+/// you should also have access to an `ImplicitCtxt` through the functions
+/// in this module.
+#[derive(Clone)]
+pub struct ImplicitCtxt<'a, 'tcx> {
+    /// The current `TyCtxt`.
+    pub tcx: TyCtxt<'tcx>,
+
+    /// The current query job, if any. This is updated by `JobOwner::start` in
+    /// `ty::query::plumbing` when executing a query.
+    pub query: Option<query::QueryJobId>,
+
+    /// Where to store diagnostics for the current query job, if any.
+    /// This is updated by `JobOwner::start` in `ty::query::plumbing` when executing a query.
+    pub diagnostics: Option<&'a Lock<ThinVec<Diagnostic>>>,
+
+    /// Used to prevent queries from calling too deeply.
+    pub query_depth: usize,
+
+    /// The current dep graph task. This is used to add dependencies to queries
+    /// when executing them.
+    pub task_deps: TaskDepsRef<'a>,
+}
+
+impl<'a, 'tcx> ImplicitCtxt<'a, 'tcx> {
+    pub fn new(gcx: &'tcx GlobalCtxt<'tcx>) -> Self {
+        let tcx = TyCtxt { gcx };
+        ImplicitCtxt {
+            tcx,
+            query: None,
+            diagnostics: None,
+            query_depth: 0,
+            task_deps: TaskDepsRef::Ignore,
+        }
+    }
+}
+
+#[cfg(parallel_compiler)]
+mod tlv {
+    use rustc_rayon_core as rayon_core;
+    use std::ptr;
+
+    /// Gets Rayon's thread-local variable, which is preserved for Rayon jobs.
+    /// This is used to get the pointer to the current `ImplicitCtxt`.
+    #[inline]
+    pub(super) fn get_tlv() -> *const () {
+        ptr::from_exposed_addr(rayon_core::tlv::get())
+    }
+
+    /// Sets Rayon's thread-local variable, which is preserved for Rayon jobs
+    /// to `value` during the call to `f`. It is restored to its previous value after.
+    /// This is used to set the pointer to the new `ImplicitCtxt`.
+    #[inline]
+    pub(super) fn with_tlv<F: FnOnce() -> R, R>(value: *const (), f: F) -> R {
+        rayon_core::tlv::with(value.expose_addr(), f)
+    }
+}
+
+#[cfg(not(parallel_compiler))]
+mod tlv {
+    use std::cell::Cell;
+    use std::ptr;
+
+    thread_local! {
+        /// A thread local variable that stores a pointer to the current `ImplicitCtxt`.
+        static TLV: Cell<*const ()> = const { Cell::new(ptr::null()) };
+    }
+
+    /// Gets the pointer to the current `ImplicitCtxt`.
+    #[inline]
+    pub(super) fn get_tlv() -> *const () {
+        TLV.with(|tlv| tlv.get())
+    }
+
+    /// Sets TLV to `value` during the call to `f`.
+    /// It is restored to its previous value after.
+    /// This is used to set the pointer to the new `ImplicitCtxt`.
+    #[inline]
+    pub(super) fn with_tlv<F: FnOnce() -> R, R>(value: *const (), f: F) -> R {
+        let old = get_tlv();
+        let _reset = rustc_data_structures::OnDrop(move || TLV.with(|tlv| tlv.set(old)));
+        TLV.with(|tlv| tlv.set(value));
+        f()
+    }
+}
+
+#[inline]
+fn erase(context: &ImplicitCtxt<'_, '_>) -> *const () {
+    context as *const _ as *const ()
+}
+
+#[inline]
+unsafe fn downcast<'a, 'tcx>(context: *const ()) -> &'a ImplicitCtxt<'a, 'tcx> {
+    &*(context as *const ImplicitCtxt<'a, 'tcx>)
+}
+
+/// Sets `context` as the new current `ImplicitCtxt` for the duration of the function `f`.
+#[inline]
+pub fn enter_context<'a, 'tcx, F, R>(context: &ImplicitCtxt<'a, 'tcx>, f: F) -> R
+where
+    F: FnOnce(&ImplicitCtxt<'a, 'tcx>) -> R,
+{
+    tlv::with_tlv(erase(context), || f(&context))
+}
+
+/// Allows access to the current `ImplicitCtxt` in a closure if one is available.
+#[inline]
+pub fn with_context_opt<F, R>(f: F) -> R
+where
+    F: for<'a, 'tcx> FnOnce(Option<&ImplicitCtxt<'a, 'tcx>>) -> R,
+{
+    let context = tlv::get_tlv();
+    if context.is_null() {
+        f(None)
+    } else {
+        // We could get an `ImplicitCtxt` pointer from another thread.
+        // Ensure that `ImplicitCtxt` is `Sync`.
+        sync::assert_sync::<ImplicitCtxt<'_, '_>>();
+
+        unsafe { f(Some(downcast(context))) }
+    }
+}
+
+/// Allows access to the current `ImplicitCtxt`.
+/// Panics if there is no `ImplicitCtxt` available.
+#[inline]
+pub fn with_context<F, R>(f: F) -> R
+where
+    F: for<'a, 'tcx> FnOnce(&ImplicitCtxt<'a, 'tcx>) -> R,
+{
+    with_context_opt(|opt_context| f(opt_context.expect("no ImplicitCtxt stored in tls")))
+}
+
+/// Allows access to the current `ImplicitCtxt` whose tcx field is the same as the tcx argument
+/// passed in. This means the closure is given an `ImplicitCtxt` with the same `'tcx` lifetime
+/// as the `TyCtxt` passed in.
+/// This will panic if you pass it a `TyCtxt` which is different from the current
+/// `ImplicitCtxt`'s `tcx` field.
+#[inline]
+pub fn with_related_context<'tcx, F, R>(tcx: TyCtxt<'tcx>, f: F) -> R
+where
+    F: FnOnce(&ImplicitCtxt<'_, 'tcx>) -> R,
+{
+    with_context(|context| {
+        // The two gcx have different invariant lifetimes, so we need to erase them for the comparison.
+        assert!(ptr::eq(
+            context.tcx.gcx as *const _ as *const (),
+            tcx.gcx as *const _ as *const ()
+        ));
+
+        let context: &ImplicitCtxt<'_, '_> = unsafe { mem::transmute(context) };
+
+        f(context)
+    })
+}
+
+/// Allows access to the `TyCtxt` in the current `ImplicitCtxt`.
+/// Panics if there is no `ImplicitCtxt` available.
+#[inline]
+pub fn with<F, R>(f: F) -> R
+where
+    F: for<'tcx> FnOnce(TyCtxt<'tcx>) -> R,
+{
+    with_context(|context| f(context.tcx))
+}
+
+/// Allows access to the `TyCtxt` in the current `ImplicitCtxt`.
+/// The closure is passed None if there is no `ImplicitCtxt` available.
+#[inline]
+pub fn with_opt<F, R>(f: F) -> R
+where
+    F: for<'tcx> FnOnce(Option<TyCtxt<'tcx>>) -> R,
+{
+    with_context_opt(|opt_context| f(opt_context.map(|context| context.tcx)))
+}