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Auto merge of rust-lang#142903 - cjgillot:local-def-path-hash, r=compiler-errors
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.
2 parents e3e96c8 + 068f3ac commit a94ed5b

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-16
lines changed

7 files changed

+39
-16
lines changed

‎compiler/rustc_hir/src/definitions.rs

Lines changed: 13 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -140,7 +140,9 @@ impl DefKey {
140140
pub(crate) fn compute_stable_hash(&self, parent: DefPathHash) -> DefPathHash {
141141
let mut hasher = StableHasher::new();
142142

143-
parent.hash(&mut hasher);
143+
// The new path is in the same crate as `parent`, and will contain the stable_crate_id.
144+
// Therefore, we only need to include information of the parent's local hash.
145+
parent.local_hash().hash(&mut hasher);
144146

145147
let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
146148

@@ -355,8 +357,16 @@ impl Definitions {
355357
},
356358
};
357359

358-
let parent_hash = DefPathHash::new(stable_crate_id, Hash64::ZERO);
359-
let def_path_hash = key.compute_stable_hash(parent_hash);
360+
// We want *both* halves of a DefPathHash to depend on the crate-id of the defining crate.
361+
// The crate-id can be more easily changed than the DefPath of an item, so, in the case of
362+
// a crate-local DefPathHash collision, the user can simply "roll the dice again" for all
363+
// DefPathHashes in the crate by changing the crate disambiguator (e.g. via bumping the
364+
// crate's version number).
365+
//
366+
// Children paths will only hash the local portion, and still inherit the change to the
367+
// root hash.
368+
let def_path_hash =
369+
DefPathHash::new(stable_crate_id, Hash64::new(stable_crate_id.as_u64()));
360370

361371
// Create the root definition.
362372
let mut table = DefPathTable::new(stable_crate_id);

‎compiler/rustc_hir/src/tests.rs

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -28,7 +28,8 @@ fn def_path_hash_depends_on_crate_id() {
2828
assert_ne!(h0.local_hash(), h1.local_hash());
2929

3030
fn mk_test_hash(stable_crate_id: StableCrateId) -> DefPathHash {
31-
let parent_hash = DefPathHash::new(stable_crate_id, Hash64::ZERO);
31+
let parent_hash =
32+
DefPathHash::new(stable_crate_id, Hash64::new(stable_crate_id.as_u64()));
3233

3334
let key = DefKey {
3435
parent: None,

‎compiler/rustc_span/src/def_id.rs

Lines changed: 15 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -110,6 +110,7 @@ impl DefPathHash {
110110

111111
/// Builds a new [DefPathHash] with the given [StableCrateId] and
112112
/// `local_hash`, where `local_hash` must be unique within its crate.
113+
#[inline]
113114
pub fn new(stable_crate_id: StableCrateId, local_hash: Hash64) -> DefPathHash {
114115
DefPathHash(Fingerprint::new(stable_crate_id.0, local_hash))
115116
}
@@ -404,21 +405,21 @@ rustc_data_structures::define_id_collections!(
404405
impl<CTX: HashStableContext> HashStable<CTX> for DefId {
405406
#[inline]
406407
fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
407-
self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
408+
hcx.def_path_hash(*self).hash_stable(hcx, hasher);
408409
}
409410
}
410411

411412
impl<CTX: HashStableContext> HashStable<CTX> for LocalDefId {
412413
#[inline]
413414
fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
414-
self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
415+
hcx.def_path_hash(self.to_def_id()).local_hash().hash_stable(hcx, hasher);
415416
}
416417
}
417418

418419
impl<CTX: HashStableContext> HashStable<CTX> for CrateNum {
419420
#[inline]
420421
fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
421-
self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
422+
self.as_def_id().to_stable_hash_key(hcx).stable_crate_id().hash_stable(hcx, hasher);
422423
}
423424
}
424425

@@ -464,30 +465,36 @@ macro_rules! typed_def_id {
464465
pub struct $Name(DefId);
465466

466467
impl $Name {
468+
#[inline]
467469
pub const fn new_unchecked(def_id: DefId) -> Self {
468470
Self(def_id)
469471
}
470472

473+
#[inline]
471474
pub fn to_def_id(self) -> DefId {
472475
self.into()
473476
}
474477

478+
#[inline]
475479
pub fn is_local(self) -> bool {
476480
self.0.is_local()
477481
}
478482

483+
#[inline]
479484
pub fn as_local(self) -> Option<$LocalName> {
480485
self.0.as_local().map($LocalName::new_unchecked)
481486
}
482487
}
483488

484489
impl From<$LocalName> for $Name {
490+
#[inline]
485491
fn from(local: $LocalName) -> Self {
486492
Self(local.0.to_def_id())
487493
}
488494
}
489495

490496
impl From<$Name> for DefId {
497+
#[inline]
491498
fn from(typed: $Name) -> Self {
492499
typed.0
493500
}
@@ -500,26 +507,31 @@ macro_rules! typed_def_id {
500507
impl !PartialOrd for $LocalName {}
501508

502509
impl $LocalName {
510+
#[inline]
503511
pub const fn new_unchecked(def_id: LocalDefId) -> Self {
504512
Self(def_id)
505513
}
506514

515+
#[inline]
507516
pub fn to_def_id(self) -> DefId {
508517
self.0.into()
509518
}
510519

520+
#[inline]
511521
pub fn to_local_def_id(self) -> LocalDefId {
512522
self.0
513523
}
514524
}
515525

516526
impl From<$LocalName> for LocalDefId {
527+
#[inline]
517528
fn from(typed: $LocalName) -> Self {
518529
typed.0
519530
}
520531
}
521532

522533
impl From<$LocalName> for DefId {
534+
#[inline]
523535
fn from(typed: $LocalName) -> Self {
524536
typed.0.into()
525537
}

‎tests/mir-opt/inline/cycle.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@ fn f(g: impl Fn()) {
1313
#[inline(always)]
1414
fn g() {
1515
// CHECK-LABEL: fn g(
16-
// CHECK-NOT: (inlined f::<fn() {main}>)
16+
// CHECK-NOT: inlined
1717
f(main);
1818
}
1919

‎tests/ui/symbol-names/basic.legacy.stderr

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,10 @@
1-
error: symbol-name(_ZN5basic4main17hc88b9d80a69d119aE)
1+
error: symbol-name(_ZN5basic4main17h1dddcfd03744167fE)
22
--> $DIR/basic.rs:8:1
33
|
44
LL | #[rustc_symbol_name]
55
| ^^^^^^^^^^^^^^^^^^^^
66

7-
error: demangling(basic::main::hc88b9d80a69d119a)
7+
error: demangling(basic::main::h1dddcfd03744167f)
88
--> $DIR/basic.rs:8:1
99
|
1010
LL | #[rustc_symbol_name]

‎tests/ui/symbol-names/issue-60925.legacy.stderr

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,10 @@
1-
error: symbol-name(_ZN11issue_609253foo37Foo$LT$issue_60925..llv$u6d$..Foo$GT$3foo17hbddb77d6f71afb32E)
1+
error: symbol-name(_ZN11issue_609253foo37Foo$LT$issue_60925..llv$u6d$..Foo$GT$3foo17h4b3099ec5dc5d306E)
22
--> $DIR/issue-60925.rs:21:9
33
|
44
LL | #[rustc_symbol_name]
55
| ^^^^^^^^^^^^^^^^^^^^
66

7-
error: demangling(issue_60925::foo::Foo<issue_60925::llvm::Foo>::foo::hbddb77d6f71afb32)
7+
error: demangling(issue_60925::foo::Foo<issue_60925::llvm::Foo>::foo::h4b3099ec5dc5d306)
88
--> $DIR/issue-60925.rs:21:9
99
|
1010
LL | #[rustc_symbol_name]

‎tests/ui/thir-print/thir-tree-match.stdout

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -94,7 +94,7 @@ body:
9494
did: DefId(0:10 ~ thir_tree_match[fcf8]::Foo)
9595
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: }]
9696
flags: IS_ENUM
97-
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 3477539199540094892 }
97+
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 13397682652773712997 }
9898
args: []
9999
variant_index: 0
100100
subpatterns: [
@@ -108,7 +108,7 @@ body:
108108
did: DefId(0:3 ~ thir_tree_match[fcf8]::Bar)
109109
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: }]
110110
flags: IS_ENUM
111-
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 10333377570083945360 }
111+
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 7908585036048874241 }
112112
args: []
113113
variant_index: 0
114114
subpatterns: []
@@ -156,7 +156,7 @@ body:
156156
did: DefId(0:10 ~ thir_tree_match[fcf8]::Foo)
157157
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: }]
158158
flags: IS_ENUM
159-
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 3477539199540094892 }
159+
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 13397682652773712997 }
160160
args: []
161161
variant_index: 0
162162
subpatterns: [
@@ -208,7 +208,7 @@ body:
208208
did: DefId(0:10 ~ thir_tree_match[fcf8]::Foo)
209209
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: }]
210210
flags: IS_ENUM
211-
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 3477539199540094892 }
211+
repr: ReprOptions { int: None, align: None, pack: None, flags: , field_shuffle_seed: 13397682652773712997 }
212212
args: []
213213
variant_index: 1
214214
subpatterns: []

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