src/librustc_macros/src/query.rs

   1 use proc_macro::TokenStream;
   2 use proc_macro2::{Delimiter, TokenTree};
   3 use quote::quote;
   4 use syn::parse::{Parse, ParseStream, Result};
   5 use syn::punctuated::Punctuated;
   6 use syn::spanned::Spanned;
   7 use syn::{
   8     braced, parenthesized, parse_macro_input, Attribute, Block, Error, Expr, Ident, ReturnType,
   9     Token, Type,
  10 };
  11
  12 #[allow(non_camel_case_types)]
  13 mod kw {
  14     syn::custom_keyword!(query);
  15 }
  16
  17 /// Ident or a wildcard `_`.
  18 struct IdentOrWild(Ident);
  19
  20 impl Parse for IdentOrWild {
  21     fn parse(input: ParseStream<'_>) -> Result<Self> {
  22         Ok(if input.peek(Token![_]) {
  23             let underscore = input.parse::<Token![_]>()?;
  24             IdentOrWild(Ident::new("_", underscore.span()))
  25         } else {
  26             IdentOrWild(input.parse()?)
  27         })
  28     }
  29 }
  30
  31 /// A modifier for a query
  32 enum QueryModifier {
  33     /// The description of the query.
  34     Desc(Option<Ident>, Punctuated<Expr, Token![,]>),
  35
  36     /// Use this type for the in-memory cache.
  37     Storage(Type),
  38
  39     /// Cache the query to disk if the `Expr` returns true.
  40     Cache(Option<(IdentOrWild, IdentOrWild)>, Block),
  41
  42     /// Custom code to load the query from disk.
  43     LoadCached(Ident, Ident, Block),
  44
  45     /// A cycle error for this query aborting the compilation with a fatal error.
  46     FatalCycle,
  47
  48     /// A cycle error results in a delay_bug call
  49     CycleDelayBug,
  50
  51     /// Don't hash the result, instead just mark a query red if it runs
  52     NoHash,
  53
  54     /// Generate a dep node based on the dependencies of the query
  55     Anon,
  56
  57     /// Always evaluate the query, ignoring its dependencies
  58     EvalAlways,
  59 }
  60
  61 impl Parse for QueryModifier {
  62     fn parse(input: ParseStream<'_>) -> Result<Self> {
  63         let modifier: Ident = input.parse()?;
  64         if modifier == "desc" {
  65             // Parse a description modifier like:
  66             // `desc { |tcx| "foo {}", tcx.item_path(key) }`
  67             let attr_content;
  68             braced!(attr_content in input);
  69             let tcx = if attr_content.peek(Token![|]) {
  70                 attr_content.parse::<Token![|]>()?;
  71                 let tcx = attr_content.parse()?;
  72                 attr_content.parse::<Token![|]>()?;
  73                 Some(tcx)
  74             } else {
  75                 None
  76             };
  77             let desc = attr_content.parse_terminated(Expr::parse)?;
  78             Ok(QueryModifier::Desc(tcx, desc))
  79         } else if modifier == "cache_on_disk_if" {
  80             // Parse a cache modifier like:
  81             // `cache(tcx, value) { |tcx| key.is_local() }`
  82             let has_args = if let TokenTree::Group(group) = input.fork().parse()? {
  83                 group.delimiter() == Delimiter::Parenthesis
  84             } else {
  85                 false
  86             };
  87             let args = if has_args {
  88                 let args;
  89                 parenthesized!(args in input);
  90                 let tcx = args.parse()?;
  91                 args.parse::<Token![,]>()?;
  92                 let value = args.parse()?;
  93                 Some((tcx, value))
  94             } else {
  95                 None
  96             };
  97             let block = input.parse()?;
  98             Ok(QueryModifier::Cache(args, block))
  99         } else if modifier == "load_cached" {
 100             // Parse a load_cached modifier like:
 101             // `load_cached(tcx, id) { tcx.queries.on_disk_cache.try_load_query_result(tcx, id) }`
 102             let args;
 103             parenthesized!(args in input);
 104             let tcx = args.parse()?;
 105             args.parse::<Token![,]>()?;
 106             let id = args.parse()?;
 107             let block = input.parse()?;
 108             Ok(QueryModifier::LoadCached(tcx, id, block))
 109         } else if modifier == "storage" {
 110             let args;
 111             parenthesized!(args in input);
 112             let ty = args.parse()?;
 113             Ok(QueryModifier::Storage(ty))
 114         } else if modifier == "fatal_cycle" {
 115             Ok(QueryModifier::FatalCycle)
 116         } else if modifier == "cycle_delay_bug" {
 117             Ok(QueryModifier::CycleDelayBug)
 118         } else if modifier == "no_hash" {
 119             Ok(QueryModifier::NoHash)
 120         } else if modifier == "anon" {
 121             Ok(QueryModifier::Anon)
 122         } else if modifier == "eval_always" {
 123             Ok(QueryModifier::EvalAlways)
 124         } else {
 125             Err(Error::new(modifier.span(), "unknown query modifier"))
 126         }
 127     }
 128 }
 129
 130 /// Ensures only doc comment attributes are used
 131 fn check_attributes(attrs: Vec<Attribute>) -> Result<()> {
 132     for attr in attrs {
 133         if !attr.path.is_ident("doc") {
 134             return Err(Error::new(attr.span(), "attributes not supported on queries"));
 135         }
 136     }
 137     Ok(())
 138 }
 139
 140 /// A compiler query. `query ... { ... }`
 141 struct Query {
 142     modifiers: List<QueryModifier>,
 143     name: Ident,
 144     key: IdentOrWild,
 145     arg: Type,
 146     result: ReturnType,
 147 }
 148
 149 impl Parse for Query {
 150     fn parse(input: ParseStream<'_>) -> Result<Self> {
 151         check_attributes(input.call(Attribute::parse_outer)?)?;
 152
 153         // Parse the query declaration. Like `query type_of(key: DefId) -> Ty<'tcx>`
 154         input.parse::<kw::query>()?;
 155         let name: Ident = input.parse()?;
 156         let arg_content;
 157         parenthesized!(arg_content in input);
 158         let key = arg_content.parse()?;
 159         arg_content.parse::<Token![:]>()?;
 160         let arg = arg_content.parse()?;
 161         let result = input.parse()?;
 162
 163         // Parse the query modifiers
 164         let content;
 165         braced!(content in input);
 166         let modifiers = content.parse()?;
 167
 168         Ok(Query { modifiers, name, key, arg, result })
 169     }
 170 }
 171
 172 /// A type used to greedily parse another type until the input is empty.
 173 struct List<T>(Vec<T>);
 174
 175 impl<T: Parse> Parse for List<T> {
 176     fn parse(input: ParseStream<'_>) -> Result<Self> {
 177         let mut list = Vec::new();
 178         while !input.is_empty() {
 179             list.push(input.parse()?);
 180         }
 181         Ok(List(list))
 182     }
 183 }
 184
 185 /// A named group containing queries.
 186 struct Group {
 187     name: Ident,
 188     queries: List<Query>,
 189 }
 190
 191 impl Parse for Group {
 192     fn parse(input: ParseStream<'_>) -> Result<Self> {
 193         let name: Ident = input.parse()?;
 194         let content;
 195         braced!(content in input);
 196         Ok(Group { name, queries: content.parse()? })
 197     }
 198 }
 199
 200 struct QueryModifiers {
 201     /// The description of the query.
 202     desc: (Option<Ident>, Punctuated<Expr, Token![,]>),
 203
 204     /// Use this type for the in-memory cache.
 205     storage: Option<Type>,
 206
 207     /// Cache the query to disk if the `Block` returns true.
 208     cache: Option<(Option<(IdentOrWild, IdentOrWild)>, Block)>,
 209
 210     /// Custom code to load the query from disk.
 211     load_cached: Option<(Ident, Ident, Block)>,
 212
 213     /// A cycle error for this query aborting the compilation with a fatal error.
 214     fatal_cycle: bool,
 215
 216     /// A cycle error results in a delay_bug call
 217     cycle_delay_bug: bool,
 218
 219     /// Don't hash the result, instead just mark a query red if it runs
 220     no_hash: bool,
 221
 222     /// Generate a dep node based on the dependencies of the query
 223     anon: bool,
 224
 225     // Always evaluate the query, ignoring its dependencies
 226     eval_always: bool,
 227 }
 228
 229 /// Process query modifiers into a struct, erroring on duplicates
 230 fn process_modifiers(query: &mut Query) -> QueryModifiers {
 231     let mut load_cached = None;
 232     let mut storage = None;
 233     let mut cache = None;
 234     let mut desc = None;
 235     let mut fatal_cycle = false;
 236     let mut cycle_delay_bug = false;
 237     let mut no_hash = false;
 238     let mut anon = false;
 239     let mut eval_always = false;
 240     for modifier in query.modifiers.0.drain(..) {
 241         match modifier {
 242             QueryModifier::LoadCached(tcx, id, block) => {
 243                 if load_cached.is_some() {
 244                     panic!("duplicate modifier `load_cached` for query `{}`", query.name);
 245                 }
 246                 load_cached = Some((tcx, id, block));
 247             }
 248             QueryModifier::Storage(ty) => {
 249                 if storage.is_some() {
 250                     panic!("duplicate modifier `storage` for query `{}`", query.name);
 251                 }
 252                 storage = Some(ty);
 253             }
 254             QueryModifier::Cache(args, expr) => {
 255                 if cache.is_some() {
 256                     panic!("duplicate modifier `cache` for query `{}`", query.name);
 257                 }
 258                 cache = Some((args, expr));
 259             }
 260             QueryModifier::Desc(tcx, list) => {
 261                 if desc.is_some() {
 262                     panic!("duplicate modifier `desc` for query `{}`", query.name);
 263                 }
 264                 desc = Some((tcx, list));
 265             }
 266             QueryModifier::FatalCycle => {
 267                 if fatal_cycle {
 268                     panic!("duplicate modifier `fatal_cycle` for query `{}`", query.name);
 269                 }
 270                 fatal_cycle = true;
 271             }
 272             QueryModifier::CycleDelayBug => {
 273                 if cycle_delay_bug {
 274                     panic!("duplicate modifier `cycle_delay_bug` for query `{}`", query.name);
 275                 }
 276                 cycle_delay_bug = true;
 277             }
 278             QueryModifier::NoHash => {
 279                 if no_hash {
 280                     panic!("duplicate modifier `no_hash` for query `{}`", query.name);
 281                 }
 282                 no_hash = true;
 283             }
 284             QueryModifier::Anon => {
 285                 if anon {
 286                     panic!("duplicate modifier `anon` for query `{}`", query.name);
 287                 }
 288                 anon = true;
 289             }
 290             QueryModifier::EvalAlways => {
 291                 if eval_always {
 292                     panic!("duplicate modifier `eval_always` for query `{}`", query.name);
 293                 }
 294                 eval_always = true;
 295             }
 296         }
 297     }
 298     let desc = desc.unwrap_or_else(|| {
 299         panic!("no description provided for query `{}`", query.name);
 300     });
 301     QueryModifiers {
 302         load_cached,
 303         storage,
 304         cache,
 305         desc,
 306         fatal_cycle,
 307         cycle_delay_bug,
 308         no_hash,
 309         anon,
 310         eval_always,
 311     }
 312 }
 313
 314 /// Add the impl of QueryDescription for the query to `impls` if one is requested
 315 fn add_query_description_impl(
 316     query: &Query,
 317     modifiers: QueryModifiers,
 318     impls: &mut proc_macro2::TokenStream,
 319 ) {
 320     let name = &query.name;
 321     let arg = &query.arg;
 322     let key = &query.key.0;
 323
 324     // Find out if we should cache the query on disk
 325     let cache = if let Some((args, expr)) = modifiers.cache.as_ref() {
 326         let try_load_from_disk = if let Some((tcx, id, block)) = modifiers.load_cached.as_ref() {
 327             // Use custom code to load the query from disk
 328             quote! {
 329                 #[inline]
 330                 fn try_load_from_disk(
 331                     #tcx: TyCtxt<'tcx>,
 332                     #id: SerializedDepNodeIndex
 333                 ) -> Option<Self::Value> {
 334                     #block
 335                 }
 336             }
 337         } else {
 338             // Use the default code to load the query from disk
 339             quote! {
 340                 #[inline]
 341                 fn try_load_from_disk(
 342                     tcx: TyCtxt<'tcx>,
 343                     id: SerializedDepNodeIndex
 344                 ) -> Option<Self::Value> {
 345                     tcx.queries.on_disk_cache.try_load_query_result(tcx, id)
 346                 }
 347             }
 348         };
 349
 350         let tcx = args
 351             .as_ref()
 352             .map(|t| {
 353                 let t = &(t.0).0;
 354                 quote! { #t }
 355             })
 356             .unwrap_or(quote! { _ });
 357         let value = args
 358             .as_ref()
 359             .map(|t| {
 360                 let t = &(t.1).0;
 361                 quote! { #t }
 362             })
 363             .unwrap_or(quote! { _ });
 364         // expr is a `Block`, meaning that `{ #expr }` gets expanded
 365         // to `{ { stmts... } }`, which triggers the `unused_braces` lint.
 366         quote! {
 367             #[inline]
 368             #[allow(unused_variables, unused_braces)]
 369             fn cache_on_disk(
 370                 #tcx: TyCtxt<'tcx>,
 371                 #key: &Self::Key,
 372                 #value: Option<&Self::Value>
 373             ) -> bool {
 374                 #expr
 375             }
 376
 377             #try_load_from_disk
 378         }
 379     } else {
 380         if modifiers.load_cached.is_some() {
 381             panic!("load_cached modifier on query `{}` without a cache modifier", name);
 382         }
 383         quote! {}
 384     };
 385
 386     let (tcx, desc) = modifiers.desc;
 387     let tcx = tcx.as_ref().map(|t| quote! { #t }).unwrap_or(quote! { _ });
 388
 389     let desc = quote! {
 390         #[allow(unused_variables)]
 391         fn describe(
 392             #tcx: TyCtxt<'tcx>,
 393             #key: #arg,
 394         ) -> Cow<'static, str> {
 395             format!(#desc).into()
 396         }
 397     };
 398
 399     impls.extend(quote! {
 400         impl<'tcx> QueryDescription<TyCtxt<'tcx>> for queries::#name<'tcx> {
 401             #desc
 402             #cache
 403         }
 404     });
 405 }
 406
 407 pub fn rustc_queries(input: TokenStream) -> TokenStream {
 408     let groups = parse_macro_input!(input as List<Group>);
 409
 410     let mut query_stream = quote! {};
 411     let mut query_description_stream = quote! {};
 412     let mut dep_node_def_stream = quote! {};
 413     let mut dep_node_force_stream = quote! {};
 414     let mut try_load_from_on_disk_cache_stream = quote! {};
 415     let mut cached_queries = quote! {};
 416
 417     for group in groups.0 {
 418         let mut group_stream = quote! {};
 419         for mut query in group.queries.0 {
 420             let modifiers = process_modifiers(&mut query);
 421             let name = &query.name;
 422             let arg = &query.arg;
 423             let result_full = &query.result;
 424             let result = match query.result {
 425                 ReturnType::Default => quote! { -> () },
 426                 _ => quote! { #result_full },
 427             };
 428
 429             if modifiers.cache.is_some() {
 430                 cached_queries.extend(quote! {
 431                     #name,
 432                 });
 433
 434                 try_load_from_on_disk_cache_stream.extend(quote! {
 435                     ::rustc_middle::dep_graph::DepKind::#name => {
 436                         if <#arg as DepNodeParams<TyCtxt<'_>>>::can_reconstruct_query_key() {
 437                             debug_assert!($tcx.dep_graph
 438                                             .node_color($dep_node)
 439                                             .map(|c| c.is_green())
 440                                             .unwrap_or(false));
 441
 442                             let key = <#arg as DepNodeParams<TyCtxt<'_>>>::recover($tcx, $dep_node).unwrap();
 443                             if queries::#name::cache_on_disk($tcx, &key, None) {
 444                                 let _ = $tcx.#name(key);
 445                             }
 446                         }
 447                     }
 448                 });
 449             }
 450
 451             let mut attributes = Vec::new();
 452
 453             // Pass on the fatal_cycle modifier
 454             if modifiers.fatal_cycle {
 455                 attributes.push(quote! { fatal_cycle });
 456             };
 457             // Pass on the storage modifier
 458             if let Some(ref ty) = modifiers.storage {
 459                 attributes.push(quote! { storage(#ty) });
 460             };
 461             // Pass on the cycle_delay_bug modifier
 462             if modifiers.cycle_delay_bug {
 463                 attributes.push(quote! { cycle_delay_bug });
 464             };
 465             // Pass on the no_hash modifier
 466             if modifiers.no_hash {
 467                 attributes.push(quote! { no_hash });
 468             };
 469             // Pass on the anon modifier
 470             if modifiers.anon {
 471                 attributes.push(quote! { anon });
 472             };
 473             // Pass on the eval_always modifier
 474             if modifiers.eval_always {
 475                 attributes.push(quote! { eval_always });
 476             };
 477
 478             let attribute_stream = quote! {#(#attributes),*};
 479
 480             // Add the query to the group
 481             group_stream.extend(quote! {
 482                 [#attribute_stream] fn #name: #name(#arg) #result,
 483             });
 484
 485             // Create a dep node for the query
 486             dep_node_def_stream.extend(quote! {
 487                 [#attribute_stream] #name(#arg),
 488             });
 489
 490             // Add a match arm to force the query given the dep node
 491             dep_node_force_stream.extend(quote! {
 492                 ::rustc_middle::dep_graph::DepKind::#name => {
 493                     if <#arg as DepNodeParams<TyCtxt<'_>>>::can_reconstruct_query_key() {
 494                         if let Some(key) = <#arg as DepNodeParams<TyCtxt<'_>>>::recover($tcx, $dep_node) {
 495                             force_query::<crate::ty::query::queries::#name<'_>, _>(
 496                                 $tcx,
 497                                 key,
 498                                 DUMMY_SP,
 499                                 *$dep_node
 500                             );
 501                             return true;
 502                         }
 503                     }
 504                 }
 505             });
 506
 507             add_query_description_impl(&query, modifiers, &mut query_description_stream);
 508         }
 509         let name = &group.name;
 510         query_stream.extend(quote! {
 511             #name { #group_stream },
 512         });
 513     }
 514
 515     dep_node_force_stream.extend(quote! {
 516         ::rustc_middle::dep_graph::DepKind::Null => {
 517             bug!("Cannot force dep node: {:?}", $dep_node)
 518         }
 519     });
 520
 521     TokenStream::from(quote! {
 522         macro_rules! rustc_query_append {
 523             ([$($macro:tt)*][$($other:tt)*]) => {
 524                 $($macro)* {
 525                     $($other)*
 526
 527                     #query_stream
 528
 529                 }
 530             }
 531         }
 532         macro_rules! rustc_dep_node_append {
 533             ([$($macro:tt)*][$($other:tt)*]) => {
 534                 $($macro)*(
 535                     $($other)*
 536
 537                     #dep_node_def_stream
 538                 );
 539             }
 540         }
 541         macro_rules! rustc_dep_node_force {
 542             ([$dep_node:expr, $tcx:expr] $($other:tt)*) => {
 543                 match $dep_node.kind {
 544                     $($other)*
 545
 546                     #dep_node_force_stream
 547                 }
 548             }
 549         }
 550         macro_rules! rustc_cached_queries {
 551             ($($macro:tt)*) => {
 552                 $($macro)*(#cached_queries);
 553             }
 554         }
 555
 556         #query_description_stream
 557
 558         macro_rules! rustc_dep_node_try_load_from_on_disk_cache {
 559             ($dep_node:expr, $tcx:expr) => {
 560                 match $dep_node.kind {
 561                     #try_load_from_on_disk_cache_stream
 562                     _ => (),
 563                 }
 564             }
 565         }
 566     })
 567 }