Auto merge of rust-lang#86674 - Aaron1011:new-querify-limits, r=michaelwoerister

Query-ify global limit attribute handling

Currently, we read various 'global limits' from inner attributes the crate root (`recursion_limit`, `move_size_limit`, `type_length_limit`, `const_eval_limit`). These limits are then stored in `Sessions`, allowing them to be access from a `TyCtxt` without registering a dependency on the crate root attributes.

This PR moves the calculation of these global limits behind queries, so that we properly track dependencies on crate root attributes. During the setup of macro expansion (before we've created a `TyCtxt`), we need to access the recursion limit, which is now done by directly calling into the code shared by the normal query implementations.

Author: bors

Diff for: compiler/rustc_interface/src/passes.rs

@@ -211,10 +211,6 @@ pub fn register_plugins<'a>(
         });
     }
 
-    sess.time("recursion_limit", || {
-        middle::limits::update_limits(sess, &krate);
-    });
-
     let mut lint_store = rustc_lint::new_lint_store(
         sess.opts.debugging_opts.no_interleave_lints,
         sess.unstable_options(),
@@ -311,9 +307,11 @@ pub fn configure_and_expand(
 
         // Create the config for macro expansion
         let features = sess.features_untracked();
+        let recursion_limit =
+            rustc_middle::middle::limits::get_recursion_limit(&krate.attrs, &sess);
         let cfg = rustc_expand::expand::ExpansionConfig {
             features: Some(&features),
-            recursion_limit: sess.recursion_limit(),
+            recursion_limit,
             trace_mac: sess.opts.debugging_opts.trace_macros,
             should_test: sess.opts.test,
             span_debug: sess.opts.debugging_opts.span_debug,
@@ -872,6 +870,13 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
                     tcx.ensure().check_mod_unstable_api_usage(module);
                     tcx.ensure().check_mod_const_bodies(module);
                 });
+            },
+            {
+                // We force these querie to run,
+                // since they might not otherwise get called.
+                // This marks the corresponding crate-level attributes
+                // as used, and ensures that their values are valid.
+                tcx.ensure().limits(());
             }
         );
     });

Diff for: compiler/rustc_middle/src/ich/hcx.rs

@@ -245,6 +245,8 @@ impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
     }
 }
 
+impl rustc_session::HashStableContext for StableHashingContext<'a> {}
+
 pub fn hash_stable_trait_impls<'a>(
     hcx: &mut StableHashingContext<'a>,
     hasher: &mut StableHasher,

Diff for: compiler/rustc_middle/src/middle/limits.rs

@@ -10,38 +10,46 @@
 //! just peeks and looks for that attribute.
 
 use crate::bug;
-use rustc_ast as ast;
-use rustc_data_structures::sync::OnceCell;
+use crate::ty;
+use rustc_ast::Attribute;
 use rustc_session::Session;
+use rustc_session::{Limit, Limits};
 use rustc_span::symbol::{sym, Symbol};
 
 use std::num::IntErrorKind;
 
-pub fn update_limits(sess: &Session, krate: &ast::Crate) {
-    update_limit(sess, krate, &sess.recursion_limit, sym::recursion_limit, 128);
-    update_limit(sess, krate, &sess.move_size_limit, sym::move_size_limit, 0);
-    update_limit(sess, krate, &sess.type_length_limit, sym::type_length_limit, 1048576);
-    update_limit(sess, krate, &sess.const_eval_limit, sym::const_eval_limit, 1_000_000);
+pub fn provide(providers: &mut ty::query::Providers) {
+    providers.limits = |tcx, ()| Limits {
+        recursion_limit: get_recursion_limit(tcx.hir().krate_attrs(), tcx.sess),
+        move_size_limit: get_limit(tcx.hir().krate_attrs(), tcx.sess, sym::move_size_limit, 0),
+        type_length_limit: get_limit(
+            tcx.hir().krate_attrs(),
+            tcx.sess,
+            sym::type_length_limit,
+            1048576,
+        ),
+        const_eval_limit: get_limit(
+            tcx.hir().krate_attrs(),
+            tcx.sess,
+            sym::const_eval_limit,
+            1_000_000,
+        ),
+    }
+}
+
+pub fn get_recursion_limit(krate_attrs: &[Attribute], sess: &Session) -> Limit {
+    get_limit(krate_attrs, sess, sym::recursion_limit, 128)
 }
 
-fn update_limit(
-    sess: &Session,
-    krate: &ast::Crate,
-    limit: &OnceCell<impl From<usize> + std::fmt::Debug>,
-    name: Symbol,
-    default: usize,
-) {
-    for attr in &krate.attrs {
+fn get_limit(krate_attrs: &[Attribute], sess: &Session, name: Symbol, default: usize) -> Limit {
+    for attr in krate_attrs {
         if !sess.check_name(attr, name) {
             continue;
         }
 
         if let Some(s) = attr.value_str() {
             match s.as_str().parse() {
-                Ok(n) => {
-                    limit.set(From::from(n)).unwrap();
-                    return;
-                }
+                Ok(n) => return Limit::new(n),
                 Err(e) => {
                     let mut err =
                         sess.struct_span_err(attr.span, "`limit` must be a non-negative integer");
@@ -68,5 +76,5 @@ fn update_limit(
             }
         }
     }
-    limit.set(From::from(default)).unwrap();
+    return Limit::new(default);
 }

Diff for: compiler/rustc_middle/src/middle/mod.rs

@@ -32,3 +32,7 @@ pub mod privacy;
 pub mod region;
 pub mod resolve_lifetime;
 pub mod stability;
+
+pub fn provide(providers: &mut crate::ty::query::Providers) {
+    limits::provide(providers);
+}

Diff for: compiler/rustc_middle/src/query/mod.rs

@@ -1725,4 +1725,8 @@ rustc_queries! {
     query conservative_is_privately_uninhabited(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
         desc { "conservatively checking if {:?} is privately uninhabited", key }
     }
+
+    query limits(key: ()) -> Limits {
+        desc { "looking up limits" }
+    }
 }

Diff for: compiler/rustc_middle/src/ty/context.rs

@@ -53,6 +53,7 @@ use rustc_middle::ty::OpaqueTypeKey;
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_session::config::{BorrowckMode, CrateType, OutputFilenames};
 use rustc_session::lint::{Level, Lint};
+use rustc_session::Limit;
 use rustc_session::Session;
 use rustc_span::def_id::StableCrateId;
 use rustc_span::source_map::MultiSpan;
@@ -1569,6 +1570,22 @@ impl<'tcx> TyCtxt<'tcx> {
             def_kind => (def_kind.article(), def_kind.descr(def_id)),
         }
     }
+
+    pub fn type_length_limit(self) -> Limit {
+        self.limits(()).type_length_limit
+    }
+
+    pub fn recursion_limit(self) -> Limit {
+        self.limits(()).recursion_limit
+    }
+
+    pub fn move_size_limit(self) -> Limit {
+        self.limits(()).move_size_limit
+    }
+
+    pub fn const_eval_limit(self) -> Limit {
+        self.limits(()).const_eval_limit
+    }
 }
 
 /// A trait implemented for all `X<'a>` types that can be safely and

Diff for: compiler/rustc_middle/src/ty/layout.rs

@@ -221,7 +221,7 @@ fn layout_raw<'tcx>(
     ty::tls::with_related_context(tcx, move |icx| {
         let (param_env, ty) = query.into_parts();
 
-        if !tcx.sess.recursion_limit().value_within_limit(icx.layout_depth) {
+        if !tcx.recursion_limit().value_within_limit(icx.layout_depth) {
             tcx.sess.fatal(&format!("overflow representing the type `{}`", ty));
         }
 

Diff for: compiler/rustc_middle/src/ty/mod.rs

@@ -1987,6 +1987,7 @@ pub fn provide(providers: &mut ty::query::Providers) {
     util::provide(providers);
     print::provide(providers);
     super::util::bug::provide(providers);
+    super::middle::provide(providers);
     *providers = ty::query::Providers {
         trait_impls_of: trait_def::trait_impls_of_provider,
         type_uninhabited_from: inhabitedness::type_uninhabited_from,

Diff for: compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1437,7 +1437,7 @@ impl<F: fmt::Write> Printer<'tcx> for FmtPrinter<'_, 'tcx, F> {
     }
 
     fn print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
-        let type_length_limit = self.tcx.sess.type_length_limit();
+        let type_length_limit = self.tcx.type_length_limit();
         if type_length_limit.value_within_limit(self.printed_type_count) {
             self.printed_type_count += 1;
             self.pretty_print_type(ty)

Diff for: compiler/rustc_middle/src/ty/query/mod.rs

@@ -49,6 +49,7 @@ use rustc_serialize::opaque;
 use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
 use rustc_session::utils::NativeLibKind;
 use rustc_session::CrateDisambiguator;
+use rustc_session::Limits;
 use rustc_target::spec::PanicStrategy;
 
 use rustc_ast as ast;

Diff for: compiler/rustc_middle/src/ty/util.rs

@@ -206,8 +206,9 @@ impl<'tcx> TyCtxt<'tcx> {
         mut ty: Ty<'tcx>,
         normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>,
     ) -> Ty<'tcx> {
+        let recursion_limit = self.recursion_limit();
         for iteration in 0.. {
-            if !self.sess.recursion_limit().value_within_limit(iteration) {
+            if !recursion_limit.value_within_limit(iteration) {
                 return self.ty_error_with_message(
                     DUMMY_SP,
                     &format!("reached the recursion limit finding the struct tail for {}", ty),

Diff for: compiler/rustc_mir/src/const_eval/eval_queries.rs

@@ -98,7 +98,7 @@ pub(super) fn mk_eval_cx<'mir, 'tcx>(
         tcx,
         root_span,
         param_env,
-        CompileTimeInterpreter::new(tcx.sess.const_eval_limit()),
+        CompileTimeInterpreter::new(tcx.const_eval_limit()),
         MemoryExtra { can_access_statics },
     )
 }
@@ -300,7 +300,7 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
         tcx,
         tcx.def_span(def.did),
         key.param_env,
-        CompileTimeInterpreter::new(tcx.sess.const_eval_limit()),
+        CompileTimeInterpreter::new(tcx.const_eval_limit()),
         // Statics (and promoteds inside statics) may access other statics, because unlike consts
         // they do not have to behave "as if" they were evaluated at runtime.
         MemoryExtra { can_access_statics: is_static },

Diff for: compiler/rustc_mir/src/const_eval/machine.rs

@@ -393,7 +393,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         frame: Frame<'mir, 'tcx>,
     ) -> InterpResult<'tcx, Frame<'mir, 'tcx>> {
         // Enforce stack size limit. Add 1 because this is run before the new frame is pushed.
-        if !ecx.tcx.sess.recursion_limit().value_within_limit(ecx.stack().len() + 1) {
+        if !ecx.recursion_limit.value_within_limit(ecx.stack().len() + 1) {
             throw_exhaust!(StackFrameLimitReached)
         } else {
             Ok(frame)

Diff for: compiler/rustc_mir/src/interpret/eval_context.rs

@@ -13,6 +13,7 @@ use rustc_middle::ty::layout::{self, TyAndLayout};
 use rustc_middle::ty::{
     self, query::TyCtxtAt, subst::SubstsRef, ParamEnv, Ty, TyCtxt, TypeFoldable,
 };
+use rustc_session::Limit;
 use rustc_span::{Pos, Span};
 use rustc_target::abi::{Align, HasDataLayout, LayoutOf, Size, TargetDataLayout};
 
@@ -39,6 +40,9 @@ pub struct InterpCx<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
 
     /// The virtual memory system.
     pub memory: Memory<'mir, 'tcx, M>,
+
+    /// The recursion limit (cached from `tcx.recursion_limit(())`)
+    pub recursion_limit: Limit,
 }
 
 // The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread
@@ -388,6 +392,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             tcx: tcx.at(root_span),
             param_env,
             memory: Memory::new(tcx, memory_extra),
+            recursion_limit: tcx.recursion_limit(),
         }
     }
 

Diff for: compiler/rustc_mir/src/monomorphize/collector.rs

@@ -200,6 +200,7 @@ use rustc_middle::ty::{self, GenericParamDefKind, Instance, Ty, TyCtxt, TypeFold
 use rustc_middle::{middle::codegen_fn_attrs::CodegenFnAttrFlags, mir::visit::TyContext};
 use rustc_session::config::EntryFnType;
 use rustc_session::lint::builtin::LARGE_ASSIGNMENTS;
+use rustc_session::Limit;
 use rustc_span::source_map::{dummy_spanned, respan, Span, Spanned, DUMMY_SP};
 use rustc_target::abi::Size;
 use smallvec::SmallVec;
@@ -294,6 +295,7 @@ pub fn collect_crate_mono_items(
 
     let mut visited = MTLock::new(FxHashSet::default());
     let mut inlining_map = MTLock::new(InliningMap::new());
+    let recursion_limit = tcx.recursion_limit();
 
     {
         let visited: MTRef<'_, _> = &mut visited;
@@ -307,6 +309,7 @@ pub fn collect_crate_mono_items(
                     dummy_spanned(root),
                     visited,
                     &mut recursion_depths,
+                    recursion_limit,
                     inlining_map,
                 );
             });
@@ -350,6 +353,7 @@ fn collect_items_rec<'tcx>(
     starting_point: Spanned<MonoItem<'tcx>>,
     visited: MTRef<'_, MTLock<FxHashSet<MonoItem<'tcx>>>>,
     recursion_depths: &mut DefIdMap<usize>,
+    recursion_limit: Limit,
     inlining_map: MTRef<'_, MTLock<InliningMap<'tcx>>>,
 ) {
     if !visited.lock_mut().insert(starting_point.node) {
@@ -409,8 +413,13 @@ fn collect_items_rec<'tcx>(
             debug_assert!(should_codegen_locally(tcx, &instance));
 
             // Keep track of the monomorphization recursion depth
-            recursion_depth_reset =
-                Some(check_recursion_limit(tcx, instance, starting_point.span, recursion_depths));
+            recursion_depth_reset = Some(check_recursion_limit(
+                tcx,
+                instance,
+                starting_point.span,
+                recursion_depths,
+                recursion_limit,
+            ));
             check_type_length_limit(tcx, instance);
 
             rustc_data_structures::stack::ensure_sufficient_stack(|| {
@@ -455,7 +464,7 @@ fn collect_items_rec<'tcx>(
     record_accesses(tcx, starting_point.node, neighbors.iter().map(|i| &i.node), inlining_map);
 
     for neighbour in neighbors {
-        collect_items_rec(tcx, neighbour, visited, recursion_depths, inlining_map);
+        collect_items_rec(tcx, neighbour, visited, recursion_depths, recursion_limit, inlining_map);
     }
 
     if let Some((def_id, depth)) = recursion_depth_reset {
@@ -523,6 +532,7 @@ fn check_recursion_limit<'tcx>(
     instance: Instance<'tcx>,
     span: Span,
     recursion_depths: &mut DefIdMap<usize>,
+    recursion_limit: Limit,
 ) -> (DefId, usize) {
     let def_id = instance.def_id();
     let recursion_depth = recursion_depths.get(&def_id).cloned().unwrap_or(0);
@@ -539,7 +549,7 @@ fn check_recursion_limit<'tcx>(
     // Code that needs to instantiate the same function recursively
     // more than the recursion limit is assumed to be causing an
     // infinite expansion.
-    if !tcx.sess.recursion_limit().value_within_limit(adjusted_recursion_depth) {
+    if !recursion_limit.value_within_limit(adjusted_recursion_depth) {
         let (shrunk, written_to_path) = shrunk_instance_name(tcx, &instance, 32, 32);
         let error = format!("reached the recursion limit while instantiating `{}`", shrunk);
         let mut err = tcx.sess.struct_span_fatal(span, &error);
@@ -577,7 +587,7 @@ fn check_type_length_limit<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
     // which means that rustc basically hangs.
     //
     // Bail out in these cases to avoid that bad user experience.
-    if !tcx.sess.type_length_limit().value_within_limit(type_length) {
+    if !tcx.type_length_limit().value_within_limit(type_length) {
         let (shrunk, written_to_path) = shrunk_instance_name(tcx, &instance, 32, 32);
         let msg = format!("reached the type-length limit while instantiating `{}`", shrunk);
         let mut diag = tcx.sess.struct_span_fatal(tcx.def_span(instance.def_id()), &msg);
@@ -814,7 +824,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
 
     fn visit_operand(&mut self, operand: &mir::Operand<'tcx>, location: Location) {
         self.super_operand(operand, location);
-        let limit = self.tcx.sess.move_size_limit();
+        let limit = self.tcx.move_size_limit().0;
         if limit == 0 {
             return;
         }