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Auto merge of #84373 - cjgillot:resolve-span, r=michaelwoerister,petrochenkov

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Encode spans relative to the enclosing item

The aim of this PR is to avoid recomputing queries when code is moved without modification.

MCP at https://github.com/rust-lang/compiler-team/issues/443

This is achieved by :
1. storing the HIR owner LocalDefId information inside the span;
2. encoding and decoding spans relative to the enclosing item in the incremental on-disk cache;
3. marking a dependency to the `source_span(LocalDefId)` query when we translate a span from the short (`Span`) representation to its explicit (`SpanData`) representation.

Since all client code uses `Span`, step 3 ensures that all manipulations
of span byte positions actually create the dependency edge between
the caller and the `source_span(LocalDefId)`.
This query return the actual absolute span of the parent item.
As a consequence, any source code motion that changes the absolute byte position of a node will either:
- modify the distance to the parent's beginning, so change the relative span's hash;
- dirty `source_span`, and trigger the incremental recomputation of all code that
  depends on the span's absolute byte position.

With this scheme, I believe the dependency tracking to be accurate.

For the moment, the spans are marked during lowering.
I'd rather do this during def-collection,
but the AST MutVisitor is not practical enough just yet.
The only difference is that we attach macro-expanded spans
to their expansion point instead of the macro itself.
This commit is contained in:
bors
2021-09-11 23:35:28 +00:00
parent 8c2b6ea37d 7842b80478
commit 547d9374d2
68 changed files with 2800 additions and 1170 deletions
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26
compiler/rustc_middle/src/hir/map/mod.rs
View File

@@ -969,22 +969,12 @@ pub(super) fn crate_hash(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Svh {
.iter_enumerated()
.filter_map(|(def_id, hod)| {
let def_path_hash = tcx.untracked_resolutions.definitions.def_path_hash(def_id);
let mut hasher = StableHasher::new();
hod.as_ref()?.hash_stable(&mut hcx, &mut hasher);
AttributeMap { map: &tcx.untracked_crate.attrs, prefix: def_id }
.hash_stable(&mut hcx, &mut hasher);
Some((def_path_hash, hasher.finish()))
let hash = hod.as_ref()?.hash;
Some((def_path_hash, hash, def_id))
})
.collect();
hir_body_nodes.sort_unstable_by_key(|bn| bn.0);
let node_hashes = hir_body_nodes.iter().fold(
Fingerprint::ZERO,
|combined_fingerprint, &(def_path_hash, fingerprint)| {
combined_fingerprint.combine(def_path_hash.0.combine(fingerprint))
},
);
let upstream_crates = upstream_crates(tcx);
// We hash the final, remapped names of all local source files so we
@@ -1004,7 +994,17 @@ pub(super) fn crate_hash(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Svh {
source_file_names.sort_unstable();
let mut stable_hasher = StableHasher::new();
node_hashes.hash_stable(&mut hcx, &mut stable_hasher);
for (def_path_hash, fingerprint, def_id) in hir_body_nodes.iter() {
def_path_hash.0.hash_stable(&mut hcx, &mut stable_hasher);
fingerprint.hash_stable(&mut hcx, &mut stable_hasher);
AttributeMap { map: &tcx.untracked_crate.attrs, prefix: *def_id }
.hash_stable(&mut hcx, &mut stable_hasher);
if tcx.sess.opts.debugging_opts.incremental_relative_spans {
let span = tcx.untracked_resolutions.definitions.def_span(*def_id);
debug_assert_eq!(span.parent(), None);
span.hash_stable(&mut hcx, &mut stable_hasher);
}
}
upstream_crates.hash_stable(&mut hcx, &mut stable_hasher);
source_file_names.hash_stable(&mut hcx, &mut stable_hasher);
tcx.sess.opts.dep_tracking_hash(true).hash_stable(&mut hcx, &mut stable_hasher);

1
compiler/rustc_middle/src/hir/mod.rs
View File

@@ -153,6 +153,7 @@ pub fn provide(providers: &mut Providers) {
index.parenting.get(&id).copied().unwrap_or(CRATE_HIR_ID)
};
providers.hir_attrs = |tcx, id| AttributeMap { map: &tcx.untracked_crate.attrs, prefix: id };
providers.source_span = |tcx, def_id| tcx.resolutions(()).definitions.def_span(def_id);
providers.def_span = |tcx, def_id| tcx.hir().span_if_local(def_id).unwrap_or(DUMMY_SP);
providers.fn_arg_names = |tcx, id| {
let hir = tcx.hir();