rust/compiler/rustc_query_impl/src/plumbing.rs

588 lines
22 KiB
Rust

//! The implementation of the query system itself. This defines the macros that
//! generate the actual methods on tcx which find and execute the provider,
//! manage the caches, and so forth.
use crate::{on_disk_cache, queries, Queries};
use rustc_middle::dep_graph::{DepKind, DepNode, DepNodeIndex, SerializedDepNodeIndex};
use rustc_middle::ty::tls::{self, ImplicitCtxt};
use rustc_middle::ty::{self, TyCtxt};
use rustc_query_system::dep_graph::HasDepContext;
use rustc_query_system::query::{
QueryContext, QueryDescription, QueryJobId, QueryMap, QuerySideEffects,
};
use rustc_data_structures::sync::Lock;
use rustc_data_structures::thin_vec::ThinVec;
use rustc_errors::{Diagnostic, Handler};
use rustc_serialize::opaque;
use rustc_span::def_id::LocalDefId;
use std::any::Any;
#[derive(Copy, Clone)]
pub struct QueryCtxt<'tcx> {
pub tcx: TyCtxt<'tcx>,
pub queries: &'tcx Queries<'tcx>,
}
impl<'tcx> std::ops::Deref for QueryCtxt<'tcx> {
type Target = TyCtxt<'tcx>;
#[inline]
fn deref(&self) -> &Self::Target {
&self.tcx
}
}
impl HasDepContext for QueryCtxt<'tcx> {
type DepKind = rustc_middle::dep_graph::DepKind;
type StableHashingContext = rustc_middle::ich::StableHashingContext<'tcx>;
type DepContext = TyCtxt<'tcx>;
#[inline]
fn dep_context(&self) -> &Self::DepContext {
&self.tcx
}
}
impl QueryContext for QueryCtxt<'tcx> {
fn current_query_job(&self) -> Option<QueryJobId<Self::DepKind>> {
tls::with_related_context(**self, |icx| icx.query)
}
fn try_collect_active_jobs(&self) -> Option<QueryMap<Self::DepKind>> {
self.queries.try_collect_active_jobs(**self)
}
fn try_load_from_on_disk_cache(&self, dep_node: &DepNode) {
let cb = &super::QUERY_CALLBACKS[dep_node.kind as usize];
(cb.try_load_from_on_disk_cache)(*self, dep_node)
}
fn try_force_from_dep_node(&self, dep_node: &DepNode) -> bool {
debug!("try_force_from_dep_node({:?}) --- trying to force", dep_node);
// We must avoid ever having to call `force_from_dep_node()` for a
// `DepNode::codegen_unit`:
// Since we cannot reconstruct the query key of a `DepNode::codegen_unit`, we
// would always end up having to evaluate the first caller of the
// `codegen_unit` query that *is* reconstructible. This might very well be
// the `compile_codegen_unit` query, thus re-codegenning the whole CGU just
// to re-trigger calling the `codegen_unit` query with the right key. At
// that point we would already have re-done all the work we are trying to
// avoid doing in the first place.
// The solution is simple: Just explicitly call the `codegen_unit` query for
// each CGU, right after partitioning. This way `try_mark_green` will always
// hit the cache instead of having to go through `force_from_dep_node`.
// This assertion makes sure, we actually keep applying the solution above.
debug_assert!(
dep_node.kind != DepKind::codegen_unit,
"calling force_from_dep_node() on DepKind::codegen_unit"
);
let cb = &super::QUERY_CALLBACKS[dep_node.kind as usize];
(cb.force_from_dep_node)(*self, dep_node)
}
// Interactions with on_disk_cache
fn load_side_effects(&self, prev_dep_node_index: SerializedDepNodeIndex) -> QuerySideEffects {
self.queries
.on_disk_cache
.as_ref()
.map(|c| c.load_side_effects(**self, prev_dep_node_index))
.unwrap_or_default()
}
fn store_side_effects(&self, dep_node_index: DepNodeIndex, side_effects: QuerySideEffects) {
if let Some(c) = self.queries.on_disk_cache.as_ref() {
c.store_side_effects(dep_node_index, side_effects)
}
}
fn store_side_effects_for_anon_node(
&self,
dep_node_index: DepNodeIndex,
side_effects: QuerySideEffects,
) {
if let Some(c) = self.queries.on_disk_cache.as_ref() {
c.store_side_effects_for_anon_node(dep_node_index, side_effects)
}
}
/// Executes a job by changing the `ImplicitCtxt` to point to the
/// new query job while it executes. It returns the diagnostics
/// captured during execution and the actual result.
#[inline(always)]
fn start_query<R>(
&self,
token: QueryJobId<Self::DepKind>,
diagnostics: Option<&Lock<ThinVec<Diagnostic>>>,
compute: impl FnOnce() -> R,
) -> R {
// The `TyCtxt` stored in TLS has the same global interner lifetime
// as `self`, so we use `with_related_context` to relate the 'tcx lifetimes
// when accessing the `ImplicitCtxt`.
tls::with_related_context(**self, move |current_icx| {
// Update the `ImplicitCtxt` to point to our new query job.
let new_icx = ImplicitCtxt {
tcx: **self,
query: Some(token),
diagnostics,
layout_depth: current_icx.layout_depth,
task_deps: current_icx.task_deps,
};
// Use the `ImplicitCtxt` while we execute the query.
tls::enter_context(&new_icx, |_| {
rustc_data_structures::stack::ensure_sufficient_stack(compute)
})
})
}
}
impl<'tcx> QueryCtxt<'tcx> {
#[inline]
pub fn from_tcx(tcx: TyCtxt<'tcx>) -> Self {
let queries = tcx.queries.as_any();
let queries = unsafe {
let queries = std::mem::transmute::<&dyn Any, &dyn Any>(queries);
let queries = queries.downcast_ref().unwrap();
let queries = std::mem::transmute::<&Queries<'_>, &Queries<'_>>(queries);
queries
};
QueryCtxt { tcx, queries }
}
crate fn on_disk_cache(self) -> Option<&'tcx on_disk_cache::OnDiskCache<'tcx>> {
self.queries.on_disk_cache.as_ref()
}
#[cfg(parallel_compiler)]
pub unsafe fn deadlock(self, registry: &rustc_rayon_core::Registry) {
rustc_query_system::query::deadlock(self, registry)
}
pub(super) fn encode_query_results(
self,
encoder: &mut on_disk_cache::CacheEncoder<'a, 'tcx, opaque::FileEncoder>,
query_result_index: &mut on_disk_cache::EncodedDepNodeIndex,
) -> opaque::FileEncodeResult {
macro_rules! encode_queries {
($($query:ident,)*) => {
$(
on_disk_cache::encode_query_results::<_, super::queries::$query<'_>>(
self,
encoder,
query_result_index
)?;
)*
}
}
rustc_cached_queries!(encode_queries!);
Ok(())
}
pub fn try_print_query_stack(
self,
query: Option<QueryJobId<DepKind>>,
handler: &Handler,
num_frames: Option<usize>,
) -> usize {
rustc_query_system::query::print_query_stack(self, query, handler, num_frames)
}
}
/// This struct stores metadata about each Query.
///
/// Information is retrieved by indexing the `QUERIES` array using the integer value
/// of the `DepKind`. Overall, this allows to implement `QueryContext` using this manual
/// jump table instead of large matches.
pub struct QueryStruct {
/// The red/green evaluation system will try to mark a specific DepNode in the
/// dependency graph as green by recursively trying to mark the dependencies of
/// that `DepNode` as green. While doing so, it will sometimes encounter a `DepNode`
/// where we don't know if it is red or green and we therefore actually have
/// to recompute its value in order to find out. Since the only piece of
/// information that we have at that point is the `DepNode` we are trying to
/// re-evaluate, we need some way to re-run a query from just that. This is what
/// `force_from_dep_node()` implements.
///
/// In the general case, a `DepNode` consists of a `DepKind` and an opaque
/// GUID/fingerprint that will uniquely identify the node. This GUID/fingerprint
/// is usually constructed by computing a stable hash of the query-key that the
/// `DepNode` corresponds to. Consequently, it is not in general possible to go
/// back from hash to query-key (since hash functions are not reversible). For
/// this reason `force_from_dep_node()` is expected to fail from time to time
/// because we just cannot find out, from the `DepNode` alone, what the
/// corresponding query-key is and therefore cannot re-run the query.
///
/// The system deals with this case letting `try_mark_green` fail which forces
/// the root query to be re-evaluated.
///
/// Now, if `force_from_dep_node()` would always fail, it would be pretty useless.
/// Fortunately, we can use some contextual information that will allow us to
/// reconstruct query-keys for certain kinds of `DepNode`s. In particular, we
/// enforce by construction that the GUID/fingerprint of certain `DepNode`s is a
/// valid `DefPathHash`. Since we also always build a huge table that maps every
/// `DefPathHash` in the current codebase to the corresponding `DefId`, we have
/// everything we need to re-run the query.
///
/// Take the `mir_promoted` query as an example. Like many other queries, it
/// just has a single parameter: the `DefId` of the item it will compute the
/// validated MIR for. Now, when we call `force_from_dep_node()` on a `DepNode`
/// with kind `MirValidated`, we know that the GUID/fingerprint of the `DepNode`
/// is actually a `DefPathHash`, and can therefore just look up the corresponding
/// `DefId` in `tcx.def_path_hash_to_def_id`.
///
/// When you implement a new query, it will likely have a corresponding new
/// `DepKind`, and you'll have to support it here in `force_from_dep_node()`. As
/// a rule of thumb, if your query takes a `DefId` or `LocalDefId` as sole parameter,
/// then `force_from_dep_node()` should not fail for it. Otherwise, you can just
/// add it to the "We don't have enough information to reconstruct..." group in
/// the match below.
pub(crate) force_from_dep_node: fn(tcx: QueryCtxt<'_>, dep_node: &DepNode) -> bool,
/// Invoke a query to put the on-disk cached value in memory.
pub(crate) try_load_from_on_disk_cache: fn(QueryCtxt<'_>, &DepNode),
}
macro_rules! handle_cycle_error {
([][$tcx: expr, $error:expr]) => {{
$error.emit();
Value::from_cycle_error($tcx)
}};
([fatal_cycle $($rest:tt)*][$tcx:expr, $error:expr]) => {{
$error.emit();
$tcx.sess.abort_if_errors();
unreachable!()
}};
([cycle_delay_bug $($rest:tt)*][$tcx:expr, $error:expr]) => {{
$error.delay_as_bug();
Value::from_cycle_error($tcx)
}};
([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*][$($args:tt)*]) => {
handle_cycle_error!([$($($modifiers)*)*][$($args)*])
};
}
macro_rules! is_anon {
([]) => {{
false
}};
([anon $($rest:tt)*]) => {{
true
}};
([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*]) => {
is_anon!([$($($modifiers)*)*])
};
}
macro_rules! is_eval_always {
([]) => {{
false
}};
([eval_always $($rest:tt)*]) => {{
true
}};
([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*]) => {
is_eval_always!([$($($modifiers)*)*])
};
}
macro_rules! hash_result {
([][$hcx:expr, $result:expr]) => {{
dep_graph::hash_result($hcx, &$result)
}};
([no_hash $($rest:tt)*][$hcx:expr, $result:expr]) => {{
None
}};
([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*][$($args:tt)*]) => {
hash_result!([$($($modifiers)*)*][$($args)*])
};
}
macro_rules! define_queries {
(<$tcx:tt>
$($(#[$attr:meta])*
[$($modifiers:tt)*] fn $name:ident($($K:tt)*) -> $V:ty,)*) => {
define_queries_struct! {
tcx: $tcx,
input: ($(([$($modifiers)*] [$($attr)*] [$name]))*)
}
mod make_query {
use super::*;
// Create an eponymous constructor for each query.
$(#[allow(nonstandard_style)] $(#[$attr])*
pub fn $name<$tcx>(tcx: QueryCtxt<$tcx>, key: query_keys::$name<$tcx>) -> QueryStackFrame {
let kind = dep_graph::DepKind::$name;
let name = stringify!($name);
// Disable visible paths printing for performance reasons.
// Showing visible path instead of any path is not that important in production.
let description = ty::print::with_no_visible_paths(
|| ty::print::with_forced_impl_filename_line(
// Force filename-line mode to avoid invoking `type_of` query.
|| queries::$name::describe(tcx, key)
));
let description = if tcx.sess.verbose() {
format!("{} [{}]", description, name)
} else {
description
};
let span = if kind == dep_graph::DepKind::def_span {
// The `def_span` query is used to calculate `default_span`,
// so exit to avoid infinite recursion.
None
} else {
Some(key.default_span(*tcx))
};
let def_id = key.key_as_def_id();
let def_kind = def_id
.and_then(|def_id| def_id.as_local())
// Use `tcx.hir().opt_def_kind()` to reduce the chance of
// accidentally triggering an infinite query loop.
.and_then(|def_id| tcx.hir().opt_def_kind(def_id))
.map(|def_kind| $crate::util::def_kind_to_simple_def_kind(def_kind));
let hash = || {
let mut hcx = tcx.create_stable_hashing_context();
let mut hasher = StableHasher::new();
std::mem::discriminant(&kind).hash_stable(&mut hcx, &mut hasher);
key.hash_stable(&mut hcx, &mut hasher);
hasher.finish::<u64>()
};
QueryStackFrame::new(name, description, span, def_kind, hash)
})*
}
#[allow(nonstandard_style)]
pub mod queries {
use std::marker::PhantomData;
$(pub struct $name<$tcx> {
data: PhantomData<&$tcx ()>
})*
}
$(impl<$tcx> QueryConfig for queries::$name<$tcx> {
type Key = query_keys::$name<$tcx>;
type Value = query_values::$name<$tcx>;
type Stored = query_stored::$name<$tcx>;
const NAME: &'static str = stringify!($name);
}
impl<$tcx> QueryAccessors<QueryCtxt<$tcx>> for queries::$name<$tcx> {
const ANON: bool = is_anon!([$($modifiers)*]);
const EVAL_ALWAYS: bool = is_eval_always!([$($modifiers)*]);
const DEP_KIND: dep_graph::DepKind = dep_graph::DepKind::$name;
type Cache = query_storage::$name<$tcx>;
#[inline(always)]
fn query_state<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryState<crate::dep_graph::DepKind, Self::Key>
where QueryCtxt<$tcx>: 'a
{
&tcx.queries.$name
}
#[inline(always)]
fn query_cache<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryCacheStore<Self::Cache>
where 'tcx:'a
{
&tcx.query_caches.$name
}
#[inline]
fn compute_fn(tcx: QueryCtxt<'tcx>, key: &Self::Key) ->
fn(TyCtxt<'tcx>, Self::Key) -> Self::Value
{
if key.query_crate_is_local() {
tcx.queries.local_providers.$name
} else {
tcx.queries.extern_providers.$name
}
}
fn hash_result(
_hcx: &mut StableHashingContext<'_>,
_result: &Self::Value
) -> Option<Fingerprint> {
hash_result!([$($modifiers)*][_hcx, _result])
}
fn handle_cycle_error(
tcx: QueryCtxt<'tcx>,
mut error: DiagnosticBuilder<'_>,
) -> Self::Value {
handle_cycle_error!([$($modifiers)*][tcx, error])
}
})*
#[allow(non_upper_case_globals)]
pub mod query_callbacks {
use super::*;
use rustc_middle::dep_graph::DepNode;
use rustc_middle::ty::query::query_keys;
use rustc_query_system::dep_graph::DepNodeParams;
use rustc_query_system::query::{force_query, QueryDescription};
// We use this for most things when incr. comp. is turned off.
pub const Null: QueryStruct = QueryStruct {
force_from_dep_node: |_, dep_node| bug!("force_from_dep_node: encountered {:?}", dep_node),
try_load_from_on_disk_cache: |_, _| {},
};
pub const TraitSelect: QueryStruct = QueryStruct {
force_from_dep_node: |_, _| false,
try_load_from_on_disk_cache: |_, _| {},
};
pub const CompileCodegenUnit: QueryStruct = QueryStruct {
force_from_dep_node: |_, _| false,
try_load_from_on_disk_cache: |_, _| {},
};
pub const CompileMonoItem: QueryStruct = QueryStruct {
force_from_dep_node: |_, _| false,
try_load_from_on_disk_cache: |_, _| {},
};
$(pub const $name: QueryStruct = {
const is_anon: bool = is_anon!([$($modifiers)*]);
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
<query_keys::$name<'_> as DepNodeParams<TyCtxt<'_>>>
::can_reconstruct_query_key()
}
fn recover<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<query_keys::$name<'tcx>> {
<query_keys::$name<'_> as DepNodeParams<TyCtxt<'_>>>::recover(tcx, dep_node)
}
fn force_from_dep_node(tcx: QueryCtxt<'_>, dep_node: &DepNode) -> bool {
force_query::<queries::$name<'_>, _>(tcx, dep_node)
}
fn try_load_from_on_disk_cache(tcx: QueryCtxt<'_>, dep_node: &DepNode) {
if is_anon {
return
}
if !can_reconstruct_query_key() {
return
}
debug_assert!(tcx.dep_graph.is_green(dep_node));
let key = recover(*tcx, dep_node).unwrap_or_else(|| panic!("Failed to recover key for {:?} with hash {}", dep_node, dep_node.hash));
if queries::$name::cache_on_disk(tcx, &key, None) {
let _ = tcx.$name(key);
}
}
QueryStruct {
force_from_dep_node,
try_load_from_on_disk_cache,
}
};)*
}
static QUERY_CALLBACKS: &[QueryStruct] = &make_dep_kind_array!(query_callbacks);
}
}
// FIXME(eddyb) this macro (and others?) use `$tcx` and `'tcx` interchangeably.
// We should either not take `$tcx` at all and use `'tcx` everywhere, or use
// `$tcx` everywhere (even if that isn't necessary due to lack of hygiene).
macro_rules! define_queries_struct {
(tcx: $tcx:tt,
input: ($(([$($modifiers:tt)*] [$($attr:tt)*] [$name:ident]))*)) => {
pub struct Queries<$tcx> {
local_providers: Box<Providers>,
extern_providers: Box<Providers>,
pub on_disk_cache: Option<OnDiskCache<$tcx>>,
$($(#[$attr])* $name: QueryState<
crate::dep_graph::DepKind,
query_keys::$name<$tcx>,
>,)*
}
impl<$tcx> Queries<$tcx> {
pub fn new(
local_providers: Providers,
extern_providers: Providers,
on_disk_cache: Option<OnDiskCache<$tcx>>,
) -> Self {
Queries {
local_providers: Box::new(local_providers),
extern_providers: Box::new(extern_providers),
on_disk_cache,
$($name: Default::default()),*
}
}
pub(crate) fn try_collect_active_jobs(
&$tcx self,
tcx: TyCtxt<$tcx>,
) -> Option<QueryMap<crate::dep_graph::DepKind>> {
let tcx = QueryCtxt { tcx, queries: self };
let mut jobs = QueryMap::default();
$(
self.$name.try_collect_active_jobs(
tcx,
dep_graph::DepKind::$name,
make_query::$name,
&mut jobs,
)?;
)*
Some(jobs)
}
}
impl QueryEngine<'tcx> for Queries<'tcx> {
fn as_any(&'tcx self) -> &'tcx dyn std::any::Any {
let this = unsafe { std::mem::transmute::<&Queries<'_>, &Queries<'_>>(self) };
this as _
}
fn try_mark_green(&'tcx self, tcx: TyCtxt<'tcx>, dep_node: &dep_graph::DepNode) -> bool {
let qcx = QueryCtxt { tcx, queries: self };
tcx.dep_graph.try_mark_green(qcx, dep_node).is_some()
}
$($(#[$attr])*
#[inline(always)]
fn $name(
&'tcx self,
tcx: TyCtxt<$tcx>,
span: Span,
key: query_keys::$name<$tcx>,
lookup: QueryLookup,
mode: QueryMode,
) -> Option<query_stored::$name<$tcx>> {
let qcx = QueryCtxt { tcx, queries: self };
get_query::<queries::$name<$tcx>, _>(qcx, span, key, lookup, mode)
})*
}
};
}
fn describe_as_module(def_id: LocalDefId, tcx: TyCtxt<'_>) -> String {
if def_id.is_top_level_module() {
"top-level module".to_string()
} else {
format!("module `{}`", tcx.def_path_str(def_id.to_def_id()))
}
}
rustc_query_description! {}