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Auto merge of #78452 - cjgillot:ddk-struct, r=Mark-Simulacrum 

Access query (DepKind) metadata through fields

This refactors the access to query definition metadata (attributes such as eval always, anon, has_params) and loading/forcing functions to generate a number of structs, instead of matching on the DepKind enum. This makes access to the fields cheaper to compile. Using a struct means that finding the metadata for a given query is just an offset away; previously the match may have been compiled to a jump table but likely not completely inlined as we expect here.

A previous attempt explored a similar strategy, but using trait objects in #78314 that proved less effective, likely due to higher overheads due to forcing dynamic calls and poorer cache utilization (all metadata is fairly densely packed with this PR).
This commit is contained in:
bors 2021-01-08 18:16:00 +00:00
parent ddf2cc7f8e 0f334c3642
commit 26438b4738
6 changed files with 377 additions and 318 deletions
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503
compiler/rustc_middle/src/dep_graph/dep_node.rs
View File

@ -29,8 +29,8 @@
//! contained no `DefId` for thing that had been removed.
//!
//! `DepNode` definition happens in the `define_dep_nodes!()` macro. This macro
//! defines the `DepKind` enum and a corresponding `DepConstructor` enum. The
//! `DepConstructor` enum links a `DepKind` to the parameters that are needed at
//! defines the `DepKind` enum and a corresponding `dep_constructor` module. The
//! `dep_constructor` module links a `DepKind` to the parameters that are needed at
//! runtime in order to construct a valid `DepNode` fingerprint.
//!
//! Because the macro sees what parameters a given `DepKind` requires, it can
@ -44,7 +44,7 @@
//! `DefId` it was computed from. In other cases, too much information gets
//! lost during fingerprint computation.
//!
//! The `DepConstructor` enum, together with `DepNode::new()`, ensures that only
//! The `dep_constructor` module, together with `DepNode::new()`, ensures that only
//! valid `DepNode` instances can be constructed. For example, the API does not
//! allow for constructing parameterless `DepNode`s with anything other
//! than a zeroed out fingerprint. More generally speaking, it relieves the
@ -66,10 +66,104 @@ use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX};
use rustc_hir::definitions::DefPathHash;
use rustc_hir::HirId;
use rustc_span::symbol::Symbol;
use rustc_span::DUMMY_SP;
use std::hash::Hash;
pub use rustc_query_system::dep_graph::{DepContext, DepNodeParams};
/// This struct stores metadata about each DepKind.
///
/// Information is retrieved by indexing the `DEP_KINDS` array using the integer value
/// of the `DepKind`. Overall, this allows to implement `DepContext` using this manual
/// jump table instead of large matches.
pub struct DepKindStruct {
/// Whether the DepNode has parameters (query keys).
pub(super) has_params: bool,
/// Anonymous queries cannot be replayed from one compiler invocation to the next.
/// When their result is needed, it is recomputed. They are useful for fine-grained
/// dependency tracking, and caching within one compiler invocation.
pub(super) is_anon: bool,
/// Eval-always queries do not track their dependencies, and are always recomputed, even if
/// their inputs have not changed since the last compiler invocation. The result is still
/// cached within one compiler invocation.
pub(super) is_eval_always: bool,
/// Whether the query key can be recovered from the hashed fingerprint.
/// See [DepNodeParams] trait for the behaviour of each key type.
// FIXME: Make this a simple boolean once DepNodeParams::can_reconstruct_query_key
// can be made a specialized associated const.
can_reconstruct_query_key: fn() -> bool,
/// 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(super) force_from_dep_node: fn(tcx: TyCtxt<'_>, dep_node: &DepNode) -> bool,
/// Invoke a query to put the on-disk cached value in memory.
pub(super) try_load_from_on_disk_cache: fn(TyCtxt<'_>, &DepNode),
}
impl std::ops::Deref for DepKind {
type Target = DepKindStruct;
fn deref(&self) -> &DepKindStruct {
&DEP_KINDS[*self as usize]
}
}
impl DepKind {
#[inline(always)]
pub fn can_reconstruct_query_key(&self) -> bool {
// Only fetch the DepKindStruct once.
let data: &DepKindStruct = &**self;
if data.is_anon {
return false;
}
(data.can_reconstruct_query_key)()
}
}
// erase!() just makes tokens go away. It's used to specify which macro argument
// is repeated (i.e., which sub-expression of the macro we are in) but don't need
// to actually use any of the arguments.
@ -103,6 +197,131 @@ macro_rules! contains_eval_always_attr {
($($attr:ident $(($($attr_args:tt)*))* ),*) => ({$(is_eval_always_attr!($attr) | )* false});
}
#[allow(non_upper_case_globals)]
pub mod dep_kind {
use super::*;
use crate::ty::query::{queries, query_keys};
use rustc_query_system::query::{force_query, QueryDescription};
// We use this for most things when incr. comp. is turned off.
pub const Null: DepKindStruct = DepKindStruct {
has_params: false,
is_anon: false,
is_eval_always: false,
can_reconstruct_query_key: || true,
force_from_dep_node: |_, dep_node| bug!("force_from_dep_node: encountered {:?}", dep_node),
try_load_from_on_disk_cache: |_, _| {},
};
// Represents metadata from an extern crate.
pub const CrateMetadata: DepKindStruct = DepKindStruct {
has_params: true,
is_anon: false,
is_eval_always: true,
can_reconstruct_query_key: || true,
force_from_dep_node: |_, dep_node| bug!("force_from_dep_node: encountered {:?}", dep_node),
try_load_from_on_disk_cache: |_, _| {},
};
pub const TraitSelect: DepKindStruct = DepKindStruct {
has_params: false,
is_anon: true,
is_eval_always: false,
can_reconstruct_query_key: || true,
force_from_dep_node: |_, _| false,
try_load_from_on_disk_cache: |_, _| {},
};
pub const CompileCodegenUnit: DepKindStruct = DepKindStruct {
has_params: true,
is_anon: false,
is_eval_always: false,
can_reconstruct_query_key: || false,
force_from_dep_node: |_, _| false,
try_load_from_on_disk_cache: |_, _| {},
};
macro_rules! define_query_dep_kinds {
($(
[$($attrs:tt)*]
$variant:ident $(( $tuple_arg_ty:ty $(,)? ))*
,)*) => (
$(pub const $variant: DepKindStruct = {
const has_params: bool = $({ erase!($tuple_arg_ty); true } |)* false;
const is_anon: bool = contains_anon_attr!($($attrs)*);
const is_eval_always: bool = contains_eval_always_attr!($($attrs)*);
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
<query_keys::$variant<'_> as DepNodeParams<TyCtxt<'_>>>
::can_reconstruct_query_key()
}
fn recover<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<query_keys::$variant<'tcx>> {
<query_keys::$variant<'_> as DepNodeParams<TyCtxt<'_>>>::recover(tcx, dep_node)
}
fn force_from_dep_node(tcx: TyCtxt<'_>, dep_node: &DepNode) -> bool {
if is_anon {
return false;
}
if !can_reconstruct_query_key() {
return false;
}
if let Some(key) = recover(tcx, dep_node) {
force_query::<queries::$variant<'_>, _>(
tcx,
key,
DUMMY_SP,
*dep_node
);
return true;
}
false
}
fn try_load_from_on_disk_cache(tcx: TyCtxt<'_>, dep_node: &DepNode) {
if is_anon {
return
}
if !can_reconstruct_query_key() {
return
}
debug_assert!(tcx.dep_graph
.node_color(dep_node)
.map(|c| c.is_green())
.unwrap_or(false));
let key = recover(tcx, dep_node).unwrap_or_else(|| panic!("Failed to recover key for {:?} with hash {}", dep_node, dep_node.hash));
if queries::$variant::cache_on_disk(tcx, &key, None) {
let _ = tcx.$variant(key);
}
}
DepKindStruct {
has_params,
is_anon,
is_eval_always,
can_reconstruct_query_key,
force_from_dep_node,
try_load_from_on_disk_cache,
}
};)*
);
}
rustc_dep_node_append!([define_query_dep_kinds!][]);
}
macro_rules! define_dep_nodes {
(<$tcx:tt>
$(
@ -110,72 +329,19 @@ macro_rules! define_dep_nodes {
$variant:ident $(( $tuple_arg_ty:ty $(,)? ))*
,)*
) => (
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)]
static DEP_KINDS: &[DepKindStruct] = &[ $(dep_kind::$variant),* ];
/// This enum serves as an index into the `DEP_KINDS` array.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
#[allow(non_camel_case_types)]
pub enum DepKind {
$($variant),*
}
impl DepKind {
#[allow(unreachable_code)]
pub fn can_reconstruct_query_key<$tcx>(&self) -> bool {
match *self {
$(
DepKind :: $variant => {
if contains_anon_attr!($($attrs)*) {
return false;
}
// tuple args
$({
return <$tuple_arg_ty as DepNodeParams<TyCtxt<'_>>>
::can_reconstruct_query_key();
})*
true
}
)*
}
}
pub fn is_anon(&self) -> bool {
match *self {
$(
DepKind :: $variant => { contains_anon_attr!($($attrs)*) }
)*
}
}
pub fn is_eval_always(&self) -> bool {
match *self {
$(
DepKind :: $variant => { contains_eval_always_attr!($($attrs)*) }
)*
}
}
#[allow(unreachable_code)]
pub fn has_params(&self) -> bool {
match *self {
$(
DepKind :: $variant => {
// tuple args
$({
erase!($tuple_arg_ty);
return true;
})*
false
}
)*
}
}
}
pub struct DepConstructor;
#[allow(non_camel_case_types)]
impl DepConstructor {
pub mod dep_constructor {
use super::*;
$(
#[inline(always)]
#[allow(unreachable_code, non_snake_case)]
@ -191,101 +357,10 @@ macro_rules! define_dep_nodes {
)*
}
pub type DepNode = rustc_query_system::dep_graph::DepNode<DepKind>;
// We keep a lot of `DepNode`s in memory during compilation. It's not
// required that their size stay the same, but we don't want to change
// it inadvertently. This assert just ensures we're aware of any change.
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
static_assert_size!(DepNode, 17);
#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
static_assert_size!(DepNode, 24);
pub trait DepNodeExt: Sized {
/// Construct a DepNode from the given DepKind and DefPathHash. This
/// method will assert that the given DepKind actually requires a
/// single DefId/DefPathHash parameter.
fn from_def_path_hash(def_path_hash: DefPathHash, kind: DepKind) -> Self;
/// Extracts the DefId corresponding to this DepNode. This will work
/// if two conditions are met:
///
/// 1. The Fingerprint of the DepNode actually is a DefPathHash, and
/// 2. the item that the DefPath refers to exists in the current tcx.
///
/// Condition (1) is determined by the DepKind variant of the
/// DepNode. Condition (2) might not be fulfilled if a DepNode
/// refers to something from the previous compilation session that
/// has been removed.
fn extract_def_id(&self, tcx: TyCtxt<'_>) -> Option<DefId>;
/// Used in testing
fn from_label_string(label: &str, def_path_hash: DefPathHash)
-> Result<Self, ()>;
/// Used in testing
fn has_label_string(label: &str) -> bool;
}
impl DepNodeExt for DepNode {
/// Construct a DepNode from the given DepKind and DefPathHash. This
/// method will assert that the given DepKind actually requires a
/// single DefId/DefPathHash parameter.
fn from_def_path_hash(def_path_hash: DefPathHash, kind: DepKind) -> DepNode {
debug_assert!(kind.can_reconstruct_query_key() && kind.has_params());
DepNode {
kind,
hash: def_path_hash.0.into(),
}
}
/// Extracts the DefId corresponding to this DepNode. This will work
/// if two conditions are met:
///
/// 1. The Fingerprint of the DepNode actually is a DefPathHash, and
/// 2. the item that the DefPath refers to exists in the current tcx.
///
/// Condition (1) is determined by the DepKind variant of the
/// DepNode. Condition (2) might not be fulfilled if a DepNode
/// refers to something from the previous compilation session that
/// has been removed.
fn extract_def_id(&self, tcx: TyCtxt<'tcx>) -> Option<DefId> {
if self.kind.can_reconstruct_query_key() {
tcx.queries.on_disk_cache.as_ref()?.def_path_hash_to_def_id(tcx, DefPathHash(self.hash.into()))
} else {
None
}
}
/// Used in testing
fn from_label_string(label: &str, def_path_hash: DefPathHash) -> Result<DepNode, ()> {
let kind = match label {
$(
stringify!($variant) => DepKind::$variant,
)*
_ => return Err(()),
};
if !kind.can_reconstruct_query_key() {
return Err(());
}
if kind.has_params() {
Ok(DepNode::from_def_path_hash(def_path_hash, kind))
} else {
Ok(DepNode::new_no_params(kind))
}
}
/// Used in testing
fn has_label_string(label: &str) -> bool {
match label {
$(
stringify!($variant) => true,
)*
_ => false,
}
fn dep_kind_from_label_string(label: &str) -> Result<DepKind, ()> {
match label {
$(stringify!($variant) => Ok(DepKind::$variant),)*
_ => Err(()),
}
}
@ -312,8 +387,110 @@ rustc_dep_node_append!([define_dep_nodes!][ <'tcx>
[] CompileCodegenUnit(Symbol),
]);
pub type DepNode = rustc_query_system::dep_graph::DepNode<DepKind>;
// We keep a lot of `DepNode`s in memory during compilation. It's not
// required that their size stay the same, but we don't want to change
// it inadvertently. This assert just ensures we're aware of any change.
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
static_assert_size!(DepNode, 17);
#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
static_assert_size!(DepNode, 24);
pub trait DepNodeExt: Sized {
/// Construct a DepNode from the given DepKind and DefPathHash. This
/// method will assert that the given DepKind actually requires a
/// single DefId/DefPathHash parameter.
fn from_def_path_hash(def_path_hash: DefPathHash, kind: DepKind) -> Self;
/// Extracts the DefId corresponding to this DepNode. This will work
/// if two conditions are met:
///
/// 1. The Fingerprint of the DepNode actually is a DefPathHash, and
/// 2. the item that the DefPath refers to exists in the current tcx.
///
/// Condition (1) is determined by the DepKind variant of the
/// DepNode. Condition (2) might not be fulfilled if a DepNode
/// refers to something from the previous compilation session that
/// has been removed.
fn extract_def_id(&self, tcx: TyCtxt<'_>) -> Option<DefId>;
/// Used in testing
fn from_label_string(label: &str, def_path_hash: DefPathHash) -> Result<Self, ()>;
/// Used in testing
fn has_label_string(label: &str) -> bool;
}
impl DepNodeExt for DepNode {
/// Construct a DepNode from the given DepKind and DefPathHash. This
/// method will assert that the given DepKind actually requires a
/// single DefId/DefPathHash parameter.
fn from_def_path_hash(def_path_hash: DefPathHash, kind: DepKind) -> DepNode {
debug_assert!(kind.can_reconstruct_query_key() && kind.has_params);
DepNode { kind, hash: def_path_hash.0.into() }
}
/// Extracts the DefId corresponding to this DepNode. This will work
/// if two conditions are met:
///
/// 1. The Fingerprint of the DepNode actually is a DefPathHash, and
/// 2. the item that the DefPath refers to exists in the current tcx.
///
/// Condition (1) is determined by the DepKind variant of the
/// DepNode. Condition (2) might not be fulfilled if a DepNode
/// refers to something from the previous compilation session that
/// has been removed.
fn extract_def_id(&self, tcx: TyCtxt<'tcx>) -> Option<DefId> {
if self.kind.can_reconstruct_query_key() {
tcx.queries
.on_disk_cache
.as_ref()?
.def_path_hash_to_def_id(tcx, DefPathHash(self.hash.into()))
} else {
None
}
}
/// Used in testing
fn from_label_string(label: &str, def_path_hash: DefPathHash) -> Result<DepNode, ()> {
let kind = dep_kind_from_label_string(label)?;
if !kind.can_reconstruct_query_key() {
return Err(());
}
if kind.has_params {
Ok(DepNode::from_def_path_hash(def_path_hash, kind))
} else {
Ok(DepNode::new_no_params(kind))
}
}
/// Used in testing
fn has_label_string(label: &str) -> bool {
dep_kind_from_label_string(label).is_ok()
}
}
impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for () {
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
true
}
fn to_fingerprint(&self, _: TyCtxt<'tcx>) -> Fingerprint {
Fingerprint::ZERO
}
fn recover(_: TyCtxt<'tcx>, _: &DepNode) -> Option<Self> {
Some(())
}
}
impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for DefId {
#[inline]
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
true
}
@ -342,7 +519,7 @@ impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for DefId {
}
impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for LocalDefId {
#[inline]
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
true
}
@ -361,7 +538,7 @@ impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for LocalDefId {
}
impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for CrateNum {
#[inline]
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
true
}
@ -381,7 +558,7 @@ impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for CrateNum {
}
impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for (DefId, DefId) {
#[inline]
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
false
}
@ -406,7 +583,7 @@ impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for (DefId, DefId) {
}
impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for HirId {
#[inline]
#[inline(always)]
fn can_reconstruct_query_key() -> bool {
false
}

46
compiler/rustc_middle/src/dep_graph/mod.rs
View File

@ -1,5 +1,4 @@
use crate::ich::StableHashingContext;
use crate::ty::query::try_load_from_on_disk_cache;
use crate::ty::{self, TyCtxt};
use rustc_data_structures::profiling::SelfProfilerRef;
use rustc_data_structures::sync::Lock;
@ -9,13 +8,12 @@ use rustc_hir::def_id::LocalDefId;
mod dep_node;
pub(crate) use rustc_query_system::dep_graph::DepNodeParams;
pub use rustc_query_system::dep_graph::{
debug, hash_result, DepContext, DepNodeColor, DepNodeIndex, SerializedDepNodeIndex,
WorkProduct, WorkProductId,
};
pub use dep_node::{label_strs, DepConstructor, DepKind, DepNode, DepNodeExt};
pub use dep_node::{dep_constructor, label_strs, DepKind, DepNode, DepNodeExt};
pub type DepGraph = rustc_query_system::dep_graph::DepGraph<DepKind>;
pub type TaskDeps = rustc_query_system::dep_graph::TaskDeps<DepKind>;
@ -26,18 +24,25 @@ pub type SerializedDepGraph = rustc_query_system::dep_graph::SerializedDepGraph<
impl rustc_query_system::dep_graph::DepKind for DepKind {
const NULL: Self = DepKind::Null;
fn is_eval_always(&self) -> bool {
DepKind::is_eval_always(self)
#[inline(always)]
fn can_reconstruct_query_key(&self) -> bool {
DepKind::can_reconstruct_query_key(self)
}
#[inline(always)]
fn is_eval_always(&self) -> bool {
self.is_eval_always
}
#[inline(always)]
fn has_params(&self) -> bool {
DepKind::has_params(self)
self.has_params
}
fn debug_node(node: &DepNode, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{:?}", node.kind)?;
if !node.kind.has_params() && !node.kind.is_anon() {
if !node.kind.has_params && !node.kind.is_anon {
return Ok(());
}
@ -81,10 +86,6 @@ impl rustc_query_system::dep_graph::DepKind for DepKind {
op(icx.task_deps)
})
}
fn can_reconstruct_query_key(&self) -> bool {
DepKind::can_reconstruct_query_key(self)
}
}
impl<'tcx> DepContext for TyCtxt<'tcx> {
@ -153,7 +154,26 @@ impl<'tcx> DepContext for TyCtxt<'tcx> {
}
debug!("try_force_from_dep_node({:?}) --- trying to force", dep_node);
ty::query::force_from_dep_node(*self, 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"
);
(dep_node.kind.force_from_dep_node)(*self, dep_node)
}
fn has_errors_or_delayed_span_bugs(&self) -> bool {
@ -166,7 +186,7 @@ impl<'tcx> DepContext for TyCtxt<'tcx> {
// Interactions with on_disk_cache
fn try_load_from_on_disk_cache(&self, dep_node: &DepNode) {
try_load_from_on_disk_cache(*self, dep_node)
(dep_node.kind.try_load_from_on_disk_cache)(*self, dep_node)
}
fn load_diagnostics(&self, prev_dep_node_index: SerializedDepNodeIndex) -> Vec<Diagnostic> {

4
compiler/rustc_middle/src/mir/mono.rs
View File

@ -1,4 +1,4 @@
use crate::dep_graph::{DepConstructor, DepNode, WorkProduct, WorkProductId};
use crate::dep_graph::{dep_constructor, DepNode, WorkProduct, WorkProductId};
use crate::ich::{NodeIdHashingMode, StableHashingContext};
use crate::ty::{subst::InternalSubsts, Instance, InstanceDef, SymbolName, TyCtxt};
use rustc_data_structures::base_n;
@ -358,7 +358,7 @@ impl<'tcx> CodegenUnit<'tcx> {
}
pub fn codegen_dep_node(&self, tcx: TyCtxt<'tcx>) -> DepNode {
DepConstructor::CompileCodegenUnit(tcx, self.name())
dep_constructor::CompileCodegenUnit(tcx, self.name())
}
}

134
compiler/rustc_middle/src/ty/query/mod.rs
View File

@ -1,4 +1,4 @@
use crate::dep_graph::{self, DepKind, DepNode, DepNodeParams};
use crate::dep_graph;
use crate::hir::exports::Export;
use crate::hir::map;
use crate::infer::canonical::{self, Canonical};
@ -103,138 +103,6 @@ pub use self::profiling_support::{IntoSelfProfilingString, QueryKeyStringBuilder
rustc_query_append! { [define_queries!][<'tcx>] }
/// 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 fn force_from_dep_node<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> bool {
// 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"
);
if !dep_node.kind.can_reconstruct_query_key() {
return false;
}
macro_rules! force_from_dep_node {
($($(#[$attr:meta])* [$($modifiers:tt)*] $name:ident($K:ty),)*) => {
match dep_node.kind {
// These are inputs that are expected to be pre-allocated and that
// should therefore always be red or green already.
DepKind::CrateMetadata |
// These are anonymous nodes.
DepKind::TraitSelect |
// We don't have enough information to reconstruct the query key of
// these.
DepKind::CompileCodegenUnit |
// Forcing this makes no sense.
DepKind::Null => {
bug!("force_from_dep_node: encountered {:?}", dep_node)
}
$(DepKind::$name => {
debug_assert!(<$K as DepNodeParams<TyCtxt<'_>>>::can_reconstruct_query_key());
if let Some(key) = <$K as DepNodeParams<TyCtxt<'_>>>::recover(tcx, dep_node) {
force_query::<queries::$name<'_>, _>(
tcx,
key,
DUMMY_SP,
*dep_node
);
return true;
}
})*
}
}
}
rustc_dep_node_append! { [force_from_dep_node!][] }
false
}
pub(crate) fn try_load_from_on_disk_cache<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) {
macro_rules! try_load_from_on_disk_cache {
($($name:ident,)*) => {
match dep_node.kind {
$(DepKind::$name => {
if <query_keys::$name<'tcx> as DepNodeParams<TyCtxt<'_>>>::can_reconstruct_query_key() {
debug_assert!(tcx.dep_graph
.node_color(dep_node)
.map(|c| c.is_green())
.unwrap_or(false));
let key = <query_keys::$name<'tcx> as DepNodeParams<TyCtxt<'_>>>::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);
}
}
})*
_ => (),
}
}
}
rustc_cached_queries!(try_load_from_on_disk_cache!);
}
mod sealed {
use super::{DefId, LocalDefId};

6
compiler/rustc_query_system/src/dep_graph/dep_node.rs
View File

@ -153,12 +153,6 @@ where
}
}
impl<Ctxt: DepContext> DepNodeParams<Ctxt> for () {
fn to_fingerprint(&self, _: Ctxt) -> Fingerprint {
Fingerprint::ZERO
}
}
/// A "work product" corresponds to a `.o` (or other) file that we
/// save in between runs. These IDs do not have a `DefId` but rather
/// some independent path or string that persists between runs without

2
compiler/rustc_query_system/src/dep_graph/mod.rs
View File

@ -61,7 +61,7 @@ pub trait DepContext: Copy {
}
/// Describe the different families of dependency nodes.
pub trait DepKind: Copy + fmt::Debug + Eq + Ord + Hash {
pub trait DepKind: Copy + fmt::Debug + Eq + Hash {
const NULL: Self;
/// Return whether this kind always require evaluation.