charon_lib/transform/reorder_decls.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540
use crate::common::*;
use crate::formatter::{AstFormatter, IntoFormatter};
use crate::graphs::*;
use crate::transform::TransformCtx;
use crate::ullbc_ast::*;
use derive_visitor::{Drive, Visitor};
use hashlink::{LinkedHashMap, LinkedHashSet};
use macros::{EnumAsGetters, EnumIsA, VariantIndexArity, VariantName};
use petgraph::algo::tarjan_scc;
use petgraph::graphmap::DiGraphMap;
use serde::{Deserialize, Serialize};
use std::fmt::{Debug, Display, Error};
use std::vec::Vec;
/// A (group of) top-level declaration(s), properly reordered.
/// "G" stands for "generic"
#[derive(
Debug, Clone, VariantIndexArity, VariantName, EnumAsGetters, EnumIsA, Serialize, Deserialize,
)]
#[charon::variants_suffix("Group")]
pub enum GDeclarationGroup<Id> {
/// A non-recursive declaration
NonRec(Id),
/// A (group of mutually) recursive declaration(s)
Rec(Vec<Id>),
}
/// A (group of) top-level declaration(s), properly reordered.
#[derive(
Debug, Clone, VariantIndexArity, VariantName, EnumAsGetters, EnumIsA, Serialize, Deserialize,
)]
#[charon::variants_suffix("Group")]
pub enum DeclarationGroup {
/// A type declaration group
Type(GDeclarationGroup<TypeDeclId>),
/// A function declaration group
Fun(GDeclarationGroup<FunDeclId>),
/// A global declaration group
Global(GDeclarationGroup<GlobalDeclId>),
///
TraitDecl(GDeclarationGroup<TraitDeclId>),
///
TraitImpl(GDeclarationGroup<TraitImplId>),
/// Anything that doesn't fit into these categories.
Mixed(GDeclarationGroup<AnyTransId>),
}
impl<Id: Copy> GDeclarationGroup<Id> {
pub fn get_ids(&self) -> &[Id] {
use GDeclarationGroup::*;
match self {
NonRec(id) => std::slice::from_ref(id),
Rec(ids) => ids.as_slice(),
}
}
pub fn get_any_trans_ids(&self) -> Vec<AnyTransId>
where
Id: Into<AnyTransId>,
{
self.get_ids().iter().copied().map(|id| id.into()).collect()
}
fn make_group(is_rec: bool, gr: impl Iterator<Item = AnyTransId>) -> Self
where
Id: TryFrom<AnyTransId>,
Id::Error: Debug,
{
let gr: Vec<_> = gr.map(|x| x.try_into().unwrap()).collect();
if is_rec {
GDeclarationGroup::Rec(gr)
} else {
assert!(gr.len() == 1);
GDeclarationGroup::NonRec(gr[0])
}
}
}
impl DeclarationGroup {
pub fn get_ids(&self) -> Vec<AnyTransId> {
use DeclarationGroup::*;
match self {
Type(gr) => gr.get_any_trans_ids(),
Fun(gr) => gr.get_any_trans_ids(),
Global(gr) => gr.get_any_trans_ids(),
TraitDecl(gr) => gr.get_any_trans_ids(),
TraitImpl(gr) => gr.get_any_trans_ids(),
Mixed(gr) => gr.get_any_trans_ids(),
}
}
}
#[derive(Clone, Copy)]
pub struct DeclInfo {
pub is_transparent: bool,
}
pub type DeclarationsGroups = Vec<DeclarationGroup>;
impl<Id: Display> Display for GDeclarationGroup<Id> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), Error> {
match self {
GDeclarationGroup::NonRec(id) => write!(f, "non-rec: {id}"),
GDeclarationGroup::Rec(ids) => {
write!(f, "rec: {}", vec_to_string(&|id| format!(" {id}"), ids))
}
}
}
}
impl Display for DeclarationGroup {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), Error> {
match self {
DeclarationGroup::Type(decl) => write!(f, "{{ Type(s): {decl} }}"),
DeclarationGroup::Fun(decl) => write!(f, "{{ Fun(s): {decl} }}"),
DeclarationGroup::Global(decl) => write!(f, "{{ Global(s): {decl} }}"),
DeclarationGroup::TraitDecl(decl) => write!(f, "{{ Trait decls(s): {decl} }}"),
DeclarationGroup::TraitImpl(decl) => write!(f, "{{ Trait impl(s): {decl} }}"),
DeclarationGroup::Mixed(decl) => write!(f, "{{ Mixed items: {decl} }}"),
}
}
}
#[derive(Visitor)]
#[visitor(
TypeDeclId(enter),
FunDeclId(enter),
GlobalDeclId(enter),
TraitImplId(enter),
TraitDeclId(enter),
BodyId(enter),
Ty(enter)
)]
pub struct Deps<'tcx, 'ctx> {
ctx: &'tcx TransformCtx<'ctx>,
dgraph: DiGraphMap<AnyTransId, ()>,
// Want to make sure we remember the order of insertion
graph: LinkedHashMap<AnyTransId, LinkedHashSet<AnyTransId>>,
// We use this when computing the graph
current_id: Option<AnyTransId>,
// We use this to track the trait impl block the current item belongs to
// (if relevant).
//
// We use this to ignore the references to the parent impl block.
//
// If we don't do so, when computing our dependency graph we end up with
// mutually recursive trait impl blocks/trait method impls in the presence
// of associated types (the deepest reason is that we don't normalize the
// types we query from rustc when translating the types from function
// signatures - we avoid doing so because as of now it makes resolving
// the trait params harder: if we get normalized types, we have to
// implement a normalizer on our side to make sure we correctly match
// types...).
//
//
// For instance, the problem happens if in Rust we have:
// ```text
// pub trait WithConstTy {
// type W;
// fn f(x: &mut Self::W);
// }
//
// impl WithConstTy for bool {
// type W = u64;
// fn f(_: &mut Self::W) {}
// }
// ```
//
// In LLBC we get:
//
// ```text
// impl traits::Bool::0 : traits::WithConstTy<bool>
// {
// type W = u64 with []
// fn f = traits::Bool::0::f
// }
//
// fn traits::Bool::0::f<@R0>(@1: &@R0 mut (traits::Bool::0::W)) { .. }
// // ^^^^^^^^^^^^^^^
// // refers to the trait impl
// ```
impl_trait_id: Option<TraitImplId>,
}
impl<'tcx, 'ctx> Deps<'tcx, 'ctx> {
fn new(ctx: &'tcx TransformCtx<'ctx>) -> Self {
Deps {
ctx,
dgraph: DiGraphMap::new(),
graph: LinkedHashMap::new(),
current_id: None,
impl_trait_id: None,
}
}
fn set_current_id(&mut self, ctx: &TransformCtx, id: AnyTransId) {
self.insert_node(id);
self.current_id = Some(id);
// Add the id of the trait impl trait this item belongs to, if necessary
use AnyTransId::*;
match id {
TraitDecl(_) | TraitImpl(_) => (),
Type(_) | Global(_) => {
// TODO
}
Fun(id) => {
// Lookup the function declaration.
//
// The declaration may not be present if we encountered errors.
if let Some(decl) = ctx.translated.fun_decls.get(id) {
if let ItemKind::TraitImpl { impl_id, .. } = &decl.kind {
// Register the trait decl id
self.impl_trait_id = Some(*impl_id)
}
}
}
}
}
fn unset_current_id(&mut self) {
self.current_id = None;
self.impl_trait_id = None;
}
fn insert_node(&mut self, id: AnyTransId) {
// We have to be careful about duplicate nodes
if !self.dgraph.contains_node(id) {
self.dgraph.add_node(id);
assert!(!self.graph.contains_key(&id));
self.graph.insert(id, LinkedHashSet::new());
}
}
fn insert_edge(&mut self, id1: AnyTransId) {
let id0 = self.current_id.unwrap();
self.insert_node(id1);
if !self.dgraph.contains_edge(id0, id1) {
self.dgraph.add_edge(id0, id1, ());
self.graph.get_mut(&id0).unwrap().insert(id1);
}
}
}
impl Deps<'_, '_> {
fn enter_type_decl_id(&mut self, id: &TypeDeclId) {
let id = AnyTransId::Type(*id);
self.insert_edge(id);
}
fn enter_global_decl_id(&mut self, id: &GlobalDeclId) {
let id = AnyTransId::Global(*id);
self.insert_edge(id);
}
fn enter_trait_impl_id(&mut self, id: &TraitImplId) {
// If the impl is the impl this item belongs to, we ignore it
// TODO: this is not very satisfying but this is the only way
// we have of preventing mutually recursive groups between
// method impls and trait impls in the presence of associated types...
if let Some(impl_id) = &self.impl_trait_id
&& impl_id == id
{
// Ignore
} else {
let id = AnyTransId::TraitImpl(*id);
self.insert_edge(id);
}
}
fn enter_trait_decl_id(&mut self, id: &TraitDeclId) {
let id = AnyTransId::TraitDecl(*id);
self.insert_edge(id);
}
fn enter_fun_decl_id(&mut self, id: &FunDeclId) {
let id = AnyTransId::Fun(*id);
self.insert_edge(id);
}
fn enter_body_id(&mut self, id: &BodyId) {
if let Some(body) = self.ctx.translated.bodies.get(*id) {
body.drive(self);
}
}
fn enter_ty(&mut self, ty: &Ty) {
// Recurse into the type, which doesn't happen by default.
ty.drive_inner(self);
}
}
impl AnyTransId {
fn fmt_with_ctx(&self, ctx: &TransformCtx) -> String {
use AnyTransId::*;
let ctx = ctx.into_fmt();
match self {
Type(id) => ctx.format_object(*id),
Fun(id) => ctx.format_object(*id),
Global(id) => ctx.format_object(*id),
TraitDecl(id) => ctx.format_object(*id),
TraitImpl(id) => ctx.format_object(*id),
}
}
}
impl Deps<'_, '_> {
fn fmt_with_ctx(&self, ctx: &TransformCtx) -> String {
self.dgraph
.nodes()
.map(|node| {
let edges = self
.dgraph
.edges(node)
.map(|e| format!("\n {}", e.1.fmt_with_ctx(ctx)))
.collect::<Vec<String>>()
.join(",");
format!("{} -> [{}\n]", node.fmt_with_ctx(ctx), edges)
})
.collect::<Vec<String>>()
.join(",\n")
}
}
fn compute_declarations_graph<'tcx, 'ctx>(ctx: &'tcx TransformCtx<'ctx>) -> Deps<'tcx, 'ctx> {
let mut graph = Deps::new(ctx);
for (id, item) in ctx.translated.all_items_with_ids() {
graph.set_current_id(ctx, id);
match item {
AnyTransItem::Type(d) => {
d.drive(&mut graph);
}
AnyTransItem::Fun(d) => {
// Explore the signature
d.signature.drive(&mut graph);
// Skip `d.kind`: we don't want to record a dependency to the impl block this
// belongs to.
d.body.drive(&mut graph);
}
AnyTransItem::Global(d) => {
// FIXME: shouldn't we visit the generics etc?
d.body.drive(&mut graph);
}
AnyTransItem::TraitDecl(d) => {
let TraitDecl {
def_id: _,
item_meta: _,
generics,
parent_clauses,
consts,
const_defaults,
types,
type_defaults,
type_clauses,
required_methods,
provided_methods,
} = d;
// Visit the traits referenced in the generics
generics.drive(&mut graph);
// Visit the parent clauses
parent_clauses.drive(&mut graph);
assert!(type_clauses.is_empty());
// Visit the items
consts.drive(&mut graph);
types.drive(&mut graph);
const_defaults.drive(&mut graph);
type_defaults.drive(&mut graph);
let method_ids = required_methods
.iter()
.chain(provided_methods.iter())
.map(|(_, id)| id)
.copied();
for id in method_ids {
// Important: we must ignore the function id, because
// otherwise in the presence of associated types we may
// get a mutual recursion between the function and the
// trait.
// Ex:
// ```
// trait Trait {
// type X;
// fn f(x : Trait::X);
// }
// ```
if let Some(decl) = ctx.translated.fun_decls.get(id) {
decl.signature.drive(&mut graph);
}
}
}
AnyTransItem::TraitImpl(d) => {
let TraitImpl {
def_id: _,
// Don't eplore because the `Name` contains this impl's own id.
item_meta: _,
impl_trait,
generics,
parent_trait_refs,
consts,
types,
type_clauses,
required_methods,
provided_methods,
} = d;
impl_trait.drive(&mut graph);
generics.drive(&mut graph);
parent_trait_refs.drive(&mut graph);
consts.drive(&mut graph);
types.drive(&mut graph);
type_clauses.drive(&mut graph);
required_methods.drive(&mut graph);
provided_methods.drive(&mut graph);
}
}
graph.unset_current_id();
}
graph
}
fn group_declarations_from_scc(
_ctx: &TransformCtx,
graph: Deps<'_, '_>,
reordered_sccs: SCCs<AnyTransId>,
) -> DeclarationsGroups {
let reordered_sccs = &reordered_sccs.sccs;
let mut reordered_decls: DeclarationsGroups = Vec::new();
// Iterate over the SCC ids in the proper order
for scc in reordered_sccs.iter() {
if scc.is_empty() {
// This can happen if we failed to translate the item in this group.
continue;
}
// Note that the length of an SCC should be at least 1.
let mut it = scc.iter();
let id0 = *it.next().unwrap();
let decl = graph.graph.get(&id0).unwrap();
// If an SCC has length one, the declaration may be simply recursive:
// we determine whether it is the case by checking if the def id is in
// its own set of dependencies.
let is_mutually_recursive = scc.len() > 1;
let is_simply_recursive = !is_mutually_recursive && decl.contains(&id0);
let is_rec = is_mutually_recursive || is_simply_recursive;
let all_same_kind = scc
.iter()
.all(|id| id0.variant_index_arity() == id.variant_index_arity());
let ids = scc.iter().copied();
let group: DeclarationGroup = match id0 {
_ if !all_same_kind => {
DeclarationGroup::Mixed(GDeclarationGroup::make_group(is_rec, ids))
}
AnyTransId::Type(_) => {
DeclarationGroup::Type(GDeclarationGroup::make_group(is_rec, ids))
}
AnyTransId::Fun(_) => DeclarationGroup::Fun(GDeclarationGroup::make_group(is_rec, ids)),
AnyTransId::Global(_) => {
DeclarationGroup::Global(GDeclarationGroup::make_group(is_rec, ids))
}
AnyTransId::TraitDecl(_) => {
let gr: Vec<_> = ids.map(|x| x.try_into().unwrap()).collect();
// Trait declarations often refer to `Self`, like below,
// which means they are often considered as recursive by our
// analysis. TODO: do something more precise. What is important
// is that we never use the "whole" self clause as argument,
// but rather projections over the self clause (like `<Self as Foo>::u`,
// in the declaration for `Foo`).
if gr.len() == 1 {
DeclarationGroup::TraitDecl(GDeclarationGroup::NonRec(gr[0]))
} else {
DeclarationGroup::TraitDecl(GDeclarationGroup::Rec(gr))
}
}
AnyTransId::TraitImpl(_) => {
DeclarationGroup::TraitImpl(GDeclarationGroup::make_group(is_rec, ids))
}
};
reordered_decls.push(group);
}
reordered_decls
}
pub fn compute_reordered_decls(ctx: &TransformCtx) -> DeclarationsGroups {
trace!();
// Step 1: explore the declarations to build the graph
let graph = compute_declarations_graph(ctx);
trace!("Graph:\n{}\n", graph.fmt_with_ctx(ctx));
// Step 2: Apply Tarjan's SCC (Strongly Connected Components) algorithm
let sccs = tarjan_scc(&graph.dgraph);
// Step 3: Reorder the declarations in an order as close as possible to the one
// given by the user. To be more precise, if we don't need to move
// definitions, the order in which we generate the declarations should
// be the same as the one in which the user wrote them.
// Remark: the [get_id_dependencies] function will be called once per id, meaning
// it is ok if it is not very efficient and clones values.
let get_id_dependencies = &|id| graph.graph.get(&id).unwrap().iter().copied().collect();
let all_ids: Vec<AnyTransId> = graph
.graph
.keys()
.copied()
// Don't list ids that weren't translated.
.filter(|id| ctx.translated.get_item(*id).is_some())
.collect();
let reordered_sccs = reorder_sccs::<AnyTransId>(get_id_dependencies, &all_ids, &sccs);
// Finally, generate the list of declarations
let reordered_decls = group_declarations_from_scc(ctx, graph, reordered_sccs);
trace!("{:?}", reordered_decls);
reordered_decls
}
#[cfg(test)]
mod tests {
#[test]
fn test_reorder_sccs1() {
use std::collections::BTreeSet as OrdSet;
let sccs = vec![vec![0], vec![1, 2], vec![3, 4, 5]];
let ids = vec![0, 1, 2, 3, 4, 5];
let get_deps = &|x| match x {
0 => vec![3],
1 => vec![0, 3],
_ => vec![],
};
let reordered = crate::reorder_decls::reorder_sccs(get_deps, &ids, &sccs);
assert!(reordered.sccs == vec![vec![3, 4, 5], vec![0], vec![1, 2],]);
assert!(reordered.scc_deps[0] == OrdSet::from([]));
assert!(reordered.scc_deps[1] == OrdSet::from([0]));
assert!(reordered.scc_deps[2] == OrdSet::from([0, 1]));
}
}