diff --git a/compiler/rustc_middle/src/dep_graph/dep_node.rs b/compiler/rustc_middle/src/dep_graph/dep_node.rs index 063a57e484f..ba9d0a40732 100644 --- a/compiler/rustc_middle/src/dep_graph/dep_node.rs +++ b/compiler/rustc_middle/src/dep_graph/dep_node.rs @@ -55,7 +55,6 @@ //! //! [dependency graph]: https://rustc-dev-guide.rust-lang.org/query.html -use crate::ty::query::QueryCtxt; use crate::ty::TyCtxt; use rustc_data_structures::fingerprint::Fingerprint; @@ -63,7 +62,6 @@ 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}; @@ -92,53 +90,6 @@ pub struct DepKindStruct { // 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(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), } impl std::ops::Deref for DepKind { @@ -197,8 +148,7 @@ macro_rules! contains_eval_always_attr { #[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}; + use crate::ty::query::query_keys; // We use this for most things when incr. comp. is turned off. pub const Null: DepKindStruct = DepKindStruct { @@ -207,8 +157,6 @@ pub mod dep_kind { 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: |_, _| {}, }; pub const TraitSelect: DepKindStruct = DepKindStruct { @@ -217,8 +165,6 @@ pub mod dep_kind { 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 { @@ -227,8 +173,6 @@ pub mod dep_kind { 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 { @@ -247,54 +191,11 @@ fn can_reconstruct_query_key() -> bool { ::can_reconstruct_query_key() } - fn recover<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option> { - as DepNodeParams>>::recover(tcx, dep_node) - } - - fn force_from_dep_node(tcx: QueryCtxt<'_>, 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::, _>(tcx, key, DUMMY_SP, *dep_node); - return true; - } - - false - } - - 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 - .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, } };)* ); @@ -310,7 +211,12 @@ macro_rules! define_dep_nodes { $variant:ident $(( $tuple_arg_ty:ty $(,)? ))* ,)* ) => ( - static DEP_KINDS: &[DepKindStruct] = &[ $(dep_kind::$variant),* ]; + #[macro_export] + macro_rules! make_dep_kind_array { + ($mod:ident) => {[ $(($mod::$variant),)* ]}; + } + + static DEP_KINDS: &[DepKindStruct] = &make_dep_kind_array!(dep_kind); /// This enum serves as an index into the `DEP_KINDS` array. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Encodable, Decodable)] diff --git a/compiler/rustc_middle/src/dep_graph/mod.rs b/compiler/rustc_middle/src/dep_graph/mod.rs index da9b0b7e48a..d862db2674e 100644 --- a/compiler/rustc_middle/src/dep_graph/mod.rs +++ b/compiler/rustc_middle/src/dep_graph/mod.rs @@ -3,6 +3,7 @@ use rustc_data_structures::profiling::SelfProfilerRef; use rustc_data_structures::sync::Lock; +#[macro_use] mod dep_node; pub use rustc_query_system::dep_graph::{ diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs index 6ae83a7f667..d9e88265050 100644 --- a/compiler/rustc_middle/src/lib.rs +++ b/compiler/rustc_middle/src/lib.rs @@ -76,6 +76,7 @@ #[macro_use] pub mod arena; +#[macro_use] pub mod dep_graph; pub mod hir; pub mod ich; diff --git a/compiler/rustc_middle/src/ty/query/mod.rs b/compiler/rustc_middle/src/ty/query/mod.rs index 970deb659fa..a2f3c6eedcb 100644 --- a/compiler/rustc_middle/src/ty/query/mod.rs +++ b/compiler/rustc_middle/src/ty/query/mod.rs @@ -62,6 +62,7 @@ #[macro_use] mod plumbing; pub use plumbing::QueryCtxt; +use plumbing::QueryStruct; pub(crate) use rustc_query_system::query::CycleError; use rustc_query_system::query::*; diff --git a/compiler/rustc_middle/src/ty/query/plumbing.rs b/compiler/rustc_middle/src/ty/query/plumbing.rs index 66ed3adb65a..18ae6318a00 100644 --- a/compiler/rustc_middle/src/ty/query/plumbing.rs +++ b/compiler/rustc_middle/src/ty/query/plumbing.rs @@ -69,7 +69,8 @@ fn try_collect_active_jobs( } fn try_load_from_on_disk_cache(&self, dep_node: &DepNode) { - (dep_node.kind.try_load_from_on_disk_cache)(*self, dep_node) + 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 { @@ -126,7 +127,8 @@ fn try_force_from_dep_node(&self, dep_node: &DepNode) -> bool { "calling force_from_dep_node() on DepKind::codegen_unit" ); - (dep_node.kind.force_from_dep_node)(*self, dep_node) + let cb = &super::QUERY_CALLBACKS[dep_node.kind as usize]; + (cb.force_from_dep_node)(*self, dep_node) } fn has_errors_or_delayed_span_bugs(&self) -> bool { @@ -307,6 +309,60 @@ pub fn try_print_query_stack( } } +/// 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]) => {{ $tcx.report_cycle($error).emit(); @@ -545,6 +601,89 @@ fn handle_cycle_error( } })* + #[allow(non_upper_case_globals)] + pub mod query_callbacks { + use super::*; + use crate::dep_graph::DepNode; + use crate::ty::query::{queries, 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 $name: QueryStruct = { + const is_anon: bool = is_anon!([$($modifiers)*]); + + #[inline(always)] + fn can_reconstruct_query_key() -> bool { + as DepNodeParams>> + ::can_reconstruct_query_key() + } + + fn recover<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option> { + as DepNodeParams>>::recover(tcx, dep_node) + } + + fn force_from_dep_node(tcx: QueryCtxt<'_>, dep_node: &DepNode) -> bool { + if is_anon { + return false; + } + + if !can_reconstruct_query_key() { + return false; + } + + if let Some(key) = recover(*tcx, dep_node) { + force_query::, _>(tcx, key, DUMMY_SP, *dep_node); + return true; + } + + false + } + + fn try_load_from_on_disk_cache(tcx: QueryCtxt<'_>, dep_node: &DepNode) { + if is_anon { + return + } + + if !can_reconstruct_query_key() { + return + } + + debug_assert!(tcx.dep_graph + .node_color(dep_node) + .map(|c| c.is_green()) + .unwrap_or(false)); + + let key = recover(*tcx, dep_node).unwrap_or_else(|| panic!("Failed to recover key for {:?} with hash {}", dep_node, dep_node.hash)); + if queries::$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); + define_provider_struct! { tcx: $tcx, input: ($(([$($modifiers)*] [$name] [$($K)*] [$V]))*)