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Auto merge of #142903 - cjgillot:local-def-path-hash, r=compiler-errors

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Only inherit local hash for paths

`DefPathHash`, as the counterpart of `DefId` that is stable across compiler invocations, is comprised of 2 parts. The first one is the `StableCrateId`, stable form of `CrateNum`. The second is 64 complementary bits to identify the crate-local definition.

The current implementation always hashes the full 128 bits when (1) trying to create a new child `DefPathHash` or (2) hashing a `CrateNum` or a `LocalDefId`. But we only need half that information: `LocalDefId` means that the `StableCrateId` is always the current crate's ; `CrateNum` means that we do not care about the local part.

As stable hashing is very hot in the query system, in particular hashing definitions, this is a big deal.

We still want the local part to change when the `StableCrateId` changes, to make incr-compilation errors less painful, ie. increase the likelihood that if will magically disappear by changing some code.

This PR sprinkles some `#[inline]` attributes on small functions that appeared in profiles.
This commit is contained in:
bors
2025-07-17 08:36:42 +00:00
parent f8f6997469 068f3ac20b
commit 8c12d76304
7 changed files with 39 additions and 16 deletions
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16
compiler/rustc_hir/src/definitions.rs
View File

@@ -140,7 +140,9 @@ impl DefKey {
pub(crate) fn compute_stable_hash(&self, parent: DefPathHash) -> DefPathHash {
let mut hasher = StableHasher::new();
parent.hash(&mut hasher);
// The new path is in the same crate as `parent`, and will contain the stable_crate_id.
// Therefore, we only need to include information of the parent's local hash.
parent.local_hash().hash(&mut hasher);
let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
@@ -355,8 +357,16 @@ impl Definitions {
},
};
let parent_hash = DefPathHash::new(stable_crate_id, Hash64::ZERO);
let def_path_hash = key.compute_stable_hash(parent_hash);
// We want *both* halves of a DefPathHash to depend on the crate-id of the defining crate.
// The crate-id can be more easily changed than the DefPath of an item, so, in the case of
// a crate-local DefPathHash collision, the user can simply "roll the dice again" for all
// DefPathHashes in the crate by changing the crate disambiguator (e.g. via bumping the
// crate's version number).
//
// Children paths will only hash the local portion, and still inherit the change to the
// root hash.
let def_path_hash =
DefPathHash::new(stable_crate_id, Hash64::new(stable_crate_id.as_u64()));
// Create the root definition.
let mut table = DefPathTable::new(stable_crate_id);

3
compiler/rustc_hir/src/tests.rs
View File

@@ -28,7 +28,8 @@ fn def_path_hash_depends_on_crate_id() {
assert_ne!(h0.local_hash(), h1.local_hash());
fn mk_test_hash(stable_crate_id: StableCrateId) -> DefPathHash {
let parent_hash = DefPathHash::new(stable_crate_id, Hash64::ZERO);
let parent_hash =
DefPathHash::new(stable_crate_id, Hash64::new(stable_crate_id.as_u64()));
let key = DefKey {
parent: None,

18
compiler/rustc_span/src/def_id.rs
View File

@@ -110,6 +110,7 @@ impl DefPathHash {
/// Builds a new [DefPathHash] with the given [StableCrateId] and
/// `local_hash`, where `local_hash` must be unique within its crate.
#[inline]
pub fn new(stable_crate_id: StableCrateId, local_hash: Hash64) -> DefPathHash {
DefPathHash(Fingerprint::new(stable_crate_id.0, local_hash))
}
@@ -404,21 +405,21 @@ rustc_data_structures::define_id_collections!(
impl<CTX: HashStableContext> HashStable<CTX> for DefId {
#[inline]
fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
hcx.def_path_hash(*self).hash_stable(hcx, hasher);
}
}
impl<CTX: HashStableContext> HashStable<CTX> for LocalDefId {
#[inline]
fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
hcx.def_path_hash(self.to_def_id()).local_hash().hash_stable(hcx, hasher);
}
}
impl<CTX: HashStableContext> HashStable<CTX> for CrateNum {
#[inline]
fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
self.as_def_id().to_stable_hash_key(hcx).stable_crate_id().hash_stable(hcx, hasher);
}
}
@@ -464,30 +465,36 @@ macro_rules! typed_def_id {
pub struct $Name(DefId);
impl $Name {
#[inline]
pub const fn new_unchecked(def_id: DefId) -> Self {
Self(def_id)
}
#[inline]
pub fn to_def_id(self) -> DefId {
self.into()
}
#[inline]
pub fn is_local(self) -> bool {
self.0.is_local()
}
#[inline]
pub fn as_local(self) -> Option<$LocalName> {
self.0.as_local().map($LocalName::new_unchecked)
}
}
impl From<$LocalName> for $Name {
#[inline]
fn from(local: $LocalName) -> Self {
Self(local.0.to_def_id())
}
}
impl From<$Name> for DefId {
#[inline]
fn from(typed: $Name) -> Self {
typed.0
}
@@ -500,26 +507,31 @@ macro_rules! typed_def_id {
impl !PartialOrd for $LocalName {}
impl $LocalName {
#[inline]
pub const fn new_unchecked(def_id: LocalDefId) -> Self {
Self(def_id)
}
#[inline]
pub fn to_def_id(self) -> DefId {
self.0.into()
}
#[inline]
pub fn to_local_def_id(self) -> LocalDefId {
self.0
}
}
impl From<$LocalName> for LocalDefId {
#[inline]
fn from(typed: $LocalName) -> Self {
typed.0
}
}
impl From<$LocalName> for DefId {
#[inline]
fn from(typed: $LocalName) -> Self {
typed.0.into()
}

2
tests/mir-opt/inline/cycle.rs
View File

@@ -13,7 +13,7 @@ fn f(g: impl Fn()) {
#[inline(always)]
fn g() {
// CHECK-LABEL: fn g(
// CHECK-NOT: (inlined f::<fn() {main}>)
// CHECK-NOT: inlined
f(main);
}

4
tests/ui/symbol-names/basic.legacy.stderr
View File

@@ -1,10 +1,10 @@
error: symbol-name(_ZN5basic4main17hc88b9d80a69d119aE)
error: symbol-name(_ZN5basic4main17h1dddcfd03744167fE)
--> $DIR/basic.rs:8:1
|
LL | #[rustc_symbol_name]
| ^^^^^^^^^^^^^^^^^^^^
error: demangling(basic::main::hc88b9d80a69d119a)
error: demangling(basic::main::h1dddcfd03744167f)
--> $DIR/basic.rs:8:1
|
LL | #[rustc_symbol_name]

4
tests/ui/symbol-names/issue-60925.legacy.stderr
View File

@@ -1,10 +1,10 @@
error: symbol-name(_ZN11issue_609253foo37Foo$LT$issue_60925..llv$u6d$..Foo$GT$3foo17hbddb77d6f71afb32E)
error: symbol-name(_ZN11issue_609253foo37Foo$LT$issue_60925..llv$u6d$..Foo$GT$3foo17h4b3099ec5dc5d306E)
--> $DIR/issue-60925.rs:21:9
|
LL | #[rustc_symbol_name]
| ^^^^^^^^^^^^^^^^^^^^
error: demangling(issue_60925::foo::Foo<issue_60925::llvm::Foo>::foo::hbddb77d6f71afb32)
error: demangling(issue_60925::foo::Foo<issue_60925::llvm::Foo>::foo::h4b3099ec5dc5d306)
--> $DIR/issue-60925.rs:21:9
|
LL | #[rustc_symbol_name]

8
tests/ui/thir-print/thir-tree-match.stdout
View File

@@ -94,7 +94,7 @@ body:
did: DefId(0:10 ~ thir_tree_match[fcf8]::Foo)
variants: [VariantDef { def_id: DefId(0:11 ~ thir_tree_match[fcf8]::Foo::FooOne), ctor: Some((Fn, DefId(0:12 ~ thir_tree_match[fcf8]::Foo::FooOne::{constructor#0}))), name: "FooOne", discr: Relative(0), fields: [FieldDef { did: DefId(0:13 ~ thir_tree_match[fcf8]::Foo::FooOne::0), name: "0", vis: Restricted(DefId(0:0 ~ thir_tree_match[fcf8])), safety: Safe, value: None }], tainted: None, flags: }, VariantDef { def_id: DefId(0:14 ~ thir_tree_match[fcf8]::Foo::FooTwo), ctor: Some((Const, DefId(0:15 ~ thir_tree_match[fcf8]::Foo::FooTwo::{constructor#0}))), name: "FooTwo", discr: Relative(1), fields: [], tainted: None, flags: }]
flags: IS_ENUM
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 3477539199540094892 }
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 13397682652773712997 }
args: []
variant_index: 0
subpatterns: [
@@ -108,7 +108,7 @@ body:
did: DefId(0:3 ~ thir_tree_match[fcf8]::Bar)
variants: [VariantDef { def_id: DefId(0:4 ~ thir_tree_match[fcf8]::Bar::First), ctor: Some((Const, DefId(0:5 ~ thir_tree_match[fcf8]::Bar::First::{constructor#0}))), name: "First", discr: Relative(0), fields: [], tainted: None, flags: }, VariantDef { def_id: DefId(0:6 ~ thir_tree_match[fcf8]::Bar::Second), ctor: Some((Const, DefId(0:7 ~ thir_tree_match[fcf8]::Bar::Second::{constructor#0}))), name: "Second", discr: Relative(1), fields: [], tainted: None, flags: }, VariantDef { def_id: DefId(0:8 ~ thir_tree_match[fcf8]::Bar::Third), ctor: Some((Const, DefId(0:9 ~ thir_tree_match[fcf8]::Bar::Third::{constructor#0}))), name: "Third", discr: Relative(2), fields: [], tainted: None, flags: }]
flags: IS_ENUM
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 10333377570083945360 }
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 7908585036048874241 }
args: []
variant_index: 0
subpatterns: []
@@ -156,7 +156,7 @@ body:
did: DefId(0:10 ~ thir_tree_match[fcf8]::Foo)
variants: [VariantDef { def_id: DefId(0:11 ~ thir_tree_match[fcf8]::Foo::FooOne), ctor: Some((Fn, DefId(0:12 ~ thir_tree_match[fcf8]::Foo::FooOne::{constructor#0}))), name: "FooOne", discr: Relative(0), fields: [FieldDef { did: DefId(0:13 ~ thir_tree_match[fcf8]::Foo::FooOne::0), name: "0", vis: Restricted(DefId(0:0 ~ thir_tree_match[fcf8])), safety: Safe, value: None }], tainted: None, flags: }, VariantDef { def_id: DefId(0:14 ~ thir_tree_match[fcf8]::Foo::FooTwo), ctor: Some((Const, DefId(0:15 ~ thir_tree_match[fcf8]::Foo::FooTwo::{constructor#0}))), name: "FooTwo", discr: Relative(1), fields: [], tainted: None, flags: }]
flags: IS_ENUM
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 3477539199540094892 }
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 13397682652773712997 }
args: []
variant_index: 0
subpatterns: [
@@ -208,7 +208,7 @@ body:
did: DefId(0:10 ~ thir_tree_match[fcf8]::Foo)
variants: [VariantDef { def_id: DefId(0:11 ~ thir_tree_match[fcf8]::Foo::FooOne), ctor: Some((Fn, DefId(0:12 ~ thir_tree_match[fcf8]::Foo::FooOne::{constructor#0}))), name: "FooOne", discr: Relative(0), fields: [FieldDef { did: DefId(0:13 ~ thir_tree_match[fcf8]::Foo::FooOne::0), name: "0", vis: Restricted(DefId(0:0 ~ thir_tree_match[fcf8])), safety: Safe, value: None }], tainted: None, flags: }, VariantDef { def_id: DefId(0:14 ~ thir_tree_match[fcf8]::Foo::FooTwo), ctor: Some((Const, DefId(0:15 ~ thir_tree_match[fcf8]::Foo::FooTwo::{constructor#0}))), name: "FooTwo", discr: Relative(1), fields: [], tainted: None, flags: }]
flags: IS_ENUM
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 3477539199540094892 }
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 13397682652773712997 }
args: []
variant_index: 1
subpatterns: []