bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Add projection query for upstream drop-glue instances.

Browse source 
This reduces the amount of invalidated data when new types are
add to upstream crates.
This commit is contained in:
Michael Woerister 2020-01-22 12:17:21 +01:00
parent 2ceb92bc53
commit 197cc1e43a
8 changed files with 138 additions and 98 deletions
Download patch file Download diff file Expand all files Collapse all files

30
src/librustc/middle/exported_symbols.rs
View file

@ -1,9 +1,7 @@
use crate::ich::StableHashingContext;
use crate::ty::subst::SubstsRef;
use crate::ty::{self, TyCtxt};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use crate::ty::{self, Ty, TyCtxt};
use rustc_hir::def_id::{DefId, LOCAL_CRATE};
use std::mem;
use rustc_macros::HashStable;
/// The SymbolExportLevel of a symbols specifies from which kinds of crates
/// the symbol will be exported. `C` symbols will be exported from any
@ -23,10 +21,11 @@ impl SymbolExportLevel {
}
}
#[derive(Eq, PartialEq, Debug, Copy, Clone, RustcEncodable, RustcDecodable)]
#[derive(Eq, PartialEq, Debug, Copy, Clone, RustcEncodable, RustcDecodable, HashStable)]
pub enum ExportedSymbol<'tcx> {
NonGeneric(DefId),
Generic(DefId, SubstsRef<'tcx>),
DropGlue(Ty<'tcx>),
NoDefId(ty::SymbolName),
}
@ -39,6 +38,9 @@ impl<'tcx> ExportedSymbol<'tcx> {
ExportedSymbol::Generic(def_id, substs) => {
tcx.symbol_name(ty::Instance::new(def_id, substs))
}
ExportedSymbol::DropGlue(ty) => {
tcx.symbol_name(ty::Instance::resolve_drop_in_place(tcx, ty))
}
ExportedSymbol::NoDefId(symbol_name) => symbol_name,
}
}
@ -51,21 +53,3 @@ pub fn metadata_symbol_name(tcx: TyCtxt<'_>) -> String {
tcx.crate_disambiguator(LOCAL_CRATE).to_fingerprint().to_hex()
)
}
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ExportedSymbol<'tcx> {
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
mem::discriminant(self).hash_stable(hcx, hasher);
match *self {
ExportedSymbol::NonGeneric(def_id) => {
def_id.hash_stable(hcx, hasher);
}
ExportedSymbol::Generic(def_id, substs) => {
def_id.hash_stable(hcx, hasher);
substs.hash_stable(hcx, hasher);
}
ExportedSymbol::NoDefId(symbol_name) => {
symbol_name.hash_stable(hcx, hasher);
}
}
}
}

34
src/librustc/query/mod.rs
View file

@ -776,13 +776,47 @@ rustc_queries! {
}
Codegen {
/// The entire set of monomorphizations the local crate can safely link
/// to because they are exported from upstream crates. Do not depend on
/// this directly, as its value changes anytime a monomorphization gets
/// added or removed in any upstream crate. Instead use the narrower
/// `upstream_monomorphizations_for`, `upstream_drop_glue_for`, or, even
/// better, `Instance::upstream_monomorphization()`.
query upstream_monomorphizations(
k: CrateNum
) -> &'tcx DefIdMap<FxHashMap<SubstsRef<'tcx>, CrateNum>> {
desc { "collecting available upstream monomorphizations `{:?}`", k }
}
/// Returns the set of upstream monomorphizations available for the
/// generic function identified by the given `def_id`. The query makes
/// sure to make a stable selection if the same monomorphization is
/// available in multiple upstream crates.
///
/// You likely want to call `Instance::upstream_monomorphization()`
/// instead of invoking this query directly.
query upstream_monomorphizations_for(_: DefId)
-> Option<&'tcx FxHashMap<SubstsRef<'tcx>, CrateNum>> {}
/// Returns the upstream crate that exports drop-glue for the given
/// type (`substs` is expected to be a single-item list containing the
/// type one wants drop-glue for).
///
/// This is a subset of `upstream_monomorphizations_for` in order to
/// increase dep-tracking granularity. Otherwise adding or removing any
/// type with drop-glue in any upstream crate would invalidate all
/// functions calling drop-glue of an upstream type.
///
/// You likely want to call `Instance::upstream_monomorphization()`
/// instead of invoking this query directly.
///
/// NOTE: This query could easily be extended to also support other
/// common functions that have are large set of monomorphizations
/// (like `Clone::clone` for example).
query upstream_drop_glue_for(substs: SubstsRef<'tcx>) -> Option<CrateNum> {
desc { "available upstream drop-glue for `{:?}`", substs }
no_force
}
}
Other {

36
src/librustc/ty/instance.rs
View file

@ -4,7 +4,7 @@ use crate::traits;
use crate::ty::print::{FmtPrinter, Printer};
use crate::ty::{self, SubstsRef, Ty, TyCtxt, TypeFoldable};
use rustc_hir::def::Namespace;
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{CrateNum, DefId};
use rustc_macros::HashStable;
use rustc_target::spec::abi::Abi;
@ -91,6 +91,40 @@ impl<'tcx> Instance<'tcx> {
let ty = tcx.type_of(self.def.def_id());
tcx.subst_and_normalize_erasing_regions(self.substs, param_env, &ty)
}
/// Finds a crate that contains a monomorphization of this instance that
/// can be linked to from the local crate. A return value of `None` means
/// no upstream crate provides such an exported monomorphization.
///
/// This method already takes into account the global `-Zshare-generics`
/// setting, always returning `None` if `share-generics` is off.
pub fn upstream_monomorphization(&self, tcx: TyCtxt<'tcx>) -> Option<CrateNum> {
// If we are not in share generics mode, we don't link to upstream
// monomorphizations but always instantiate our own internal versions
// instead.
if !tcx.sess.opts.share_generics() {
return None;
}
// If this is an item that is defined in the local crate, no upstream
// crate can know about it/provide a monomorphization.
if self.def_id().is_local() {
return None;
}
// If this a non-generic instance, it cannot be a shared monomorphization.
if self.substs.non_erasable_generics().next().is_none() {
return None;
}
match self.def {
InstanceDef::Item(def_id) => tcx
.upstream_monomorphizations_for(def_id)
.and_then(|monos| monos.get(&self.substs).cloned()),
InstanceDef::DropGlue(_, Some(_)) => tcx.upstream_drop_glue_for(self.substs),
_ => None,
}
}
}
impl<'tcx> InstanceDef<'tcx> {

9
src/librustc/ty/query/keys.rs
View file

@ -116,6 +116,15 @@ impl Key for (DefId, SimplifiedType) {
}
}
impl<'tcx> Key for SubstsRef<'tcx> {
fn query_crate(&self) -> CrateNum {
LOCAL_CRATE
}
fn default_span(&self, _: TyCtxt<'_>) -> Span {
DUMMY_SP
}
}
impl<'tcx> Key for (DefId, SubstsRef<'tcx>) {
fn query_crate(&self) -> CrateNum {
self.0.krate

7
src/librustc_codegen_llvm/callee.rs
View file

@ -130,12 +130,7 @@ pub fn get_fn(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) -> &'ll Value
} else {
// This is a monomorphization of a generic function
// defined in an upstream crate.
if cx
.tcx
.upstream_monomorphizations_for(instance_def_id)
.map(|set| set.contains_key(instance.substs))
.unwrap_or(false)
{
if instance.upstream_monomorphization(tcx).is_some() {
// This is instantiated in another crate. It cannot
// be `hidden`.
} else {

63
src/librustc_codegen_ssa/back/symbol_export.rs
View file

@ -255,14 +255,13 @@ fn exported_symbols_provider_local(
symbols.push((symbol, SymbolExportLevel::Rust));
}
}
MonoItem::Fn(Instance { def: InstanceDef::DropGlue(def_id, Some(ty)), substs }) => {
MonoItem::Fn(Instance { def: InstanceDef::DropGlue(_, Some(ty)), substs }) => {
// A little sanity-check
debug_assert_eq!(
substs.non_erasable_generics().next(),
Some(GenericArgKind::Type(ty))
);
let symbol = ExportedSymbol::Generic(def_id, substs);
symbols.push((symbol, SymbolExportLevel::Rust));
symbols.push((ExportedSymbol::DropGlue(ty), SymbolExportLevel::Rust));
}
_ => {
// Any other symbols don't qualify for sharing
@ -298,24 +297,41 @@ fn upstream_monomorphizations_provider(
cnum_stable_ids
};
let drop_in_place_fn_def_id = tcx.lang_items().drop_in_place_fn();
for &cnum in cnums.iter() {
for (exported_symbol, _) in tcx.exported_symbols(cnum).iter() {
if let &ExportedSymbol::Generic(def_id, substs) = exported_symbol {
let substs_map = instances.entry(def_id).or_default();
match substs_map.entry(substs) {
Occupied(mut e) => {
// If there are multiple monomorphizations available,
// we select one deterministically.
let other_cnum = *e.get();
if cnum_stable_ids[other_cnum] > cnum_stable_ids[cnum] {
e.insert(cnum);
}
let (def_id, substs) = match *exported_symbol {
ExportedSymbol::Generic(def_id, substs) => (def_id, substs),
ExportedSymbol::DropGlue(ty) => {
if let Some(drop_in_place_fn_def_id) = drop_in_place_fn_def_id {
(drop_in_place_fn_def_id, tcx.intern_substs(&[ty.into()]))
} else {
// `drop_in_place` in place does not exist, don't try
// to use it.
continue;
}
Vacant(e) => {
}
ExportedSymbol::NonGeneric(..) | ExportedSymbol::NoDefId(..) => {
// These are no monomorphizations
continue;
}
};
let substs_map = instances.entry(def_id).or_default();
match substs_map.entry(substs) {
Occupied(mut e) => {
// If there are multiple monomorphizations available,
// we select one deterministically.
let other_cnum = *e.get();
if cnum_stable_ids[other_cnum] > cnum_stable_ids[cnum] {
e.insert(cnum);
}
}
Vacant(e) => {
e.insert(cnum);
}
}
}
}
@ -331,6 +347,17 @@ fn upstream_monomorphizations_for_provider(
tcx.upstream_monomorphizations(LOCAL_CRATE).get(&def_id)
}
fn upstream_drop_glue_for_provider<'tcx>(
tcx: TyCtxt<'tcx>,
substs: SubstsRef<'tcx>,
) -> Option<CrateNum> {
if let Some(def_id) = tcx.lang_items().drop_in_place_fn() {
tcx.upstream_monomorphizations_for(def_id).and_then(|monos| monos.get(&substs).cloned())
} else {
None
}
}
fn is_unreachable_local_definition_provider(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) {
!tcx.reachable_set(LOCAL_CRATE).contains(&hir_id)
@ -345,6 +372,7 @@ pub fn provide(providers: &mut Providers<'_>) {
providers.exported_symbols = exported_symbols_provider_local;
providers.upstream_monomorphizations = upstream_monomorphizations_provider;
providers.is_unreachable_local_definition = is_unreachable_local_definition_provider;
providers.upstream_drop_glue_for = upstream_drop_glue_for_provider;
}
pub fn provide_extern(providers: &mut Providers<'_>) {
@ -405,6 +433,11 @@ pub fn symbol_name_for_instance_in_crate<'tcx>(
Instance::new(def_id, substs),
instantiating_crate,
),
ExportedSymbol::DropGlue(ty) => symbol_names::symbol_name_for_instance_in_crate(
tcx,
Instance::resolve_drop_in_place(tcx, ty),
instantiating_crate,
),
ExportedSymbol::NoDefId(symbol_name) => symbol_name.to_string(),
}
}

25
src/librustc_codegen_utils/symbol_names.rs
View file

@ -126,29 +126,10 @@ fn symbol_name_provider(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) -> ty::Symb
// This closure determines the instantiating crate for instances that
// need an instantiating-crate-suffix for their symbol name, in order
// to differentiate between local copies.
//
// For generics we might find re-usable upstream instances. For anything
// else we rely on their being a local copy available.
if is_generic(instance.substs) {
let def_id = instance.def_id();
if !def_id.is_local() && tcx.sess.opts.share_generics() {
// If we are re-using a monomorphization from another crate,
// we have to compute the symbol hash accordingly.
let upstream_monomorphizations = tcx.upstream_monomorphizations_for(def_id);
upstream_monomorphizations
.and_then(|monos| monos.get(&instance.substs).cloned())
// If there is no instance available upstream, there'll be
// one in the current crate.
.unwrap_or(LOCAL_CRATE)
} else {
// For generic functions defined in the current crate, there
// can be no upstream instances. Also, if we don't share
// generics, we'll instantiate a local copy too.
LOCAL_CRATE
}
// For generics we might find re-usable upstream instances. If there
// is one, we rely on the symbol being instantiated locally.
instance.upstream_monomorphization(tcx).unwrap_or(LOCAL_CRATE)
} else {
// For non-generic things that need to avoid naming conflicts, we
// always instantiate a copy in the local crate.

32
src/librustc_mir/monomorphize/collector.rs
View file

@ -737,9 +737,7 @@ fn should_monomorphize_locally<'tcx>(tcx: TyCtxt<'tcx>, instance: &Instance<'tcx
return true;
}
if tcx.is_reachable_non_generic(def_id)
|| is_available_upstream_generic(tcx, def_id, instance.substs)
{
if tcx.is_reachable_non_generic(def_id) || instance.upstream_monomorphization(tcx).is_some() {
// We can link to the item in question, no instance needed
// in this crate.
return false;
@ -750,34 +748,6 @@ fn should_monomorphize_locally<'tcx>(tcx: TyCtxt<'tcx>, instance: &Instance<'tcx
}
return true;
fn is_available_upstream_generic<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: DefId,
substs: SubstsRef<'tcx>,
) -> bool {
debug_assert!(!def_id.is_local());
// If we are not in share generics mode, we don't link to upstream
// monomorphizations but always instantiate our own internal versions
// instead.
if !tcx.sess.opts.share_generics() {
return false;
}
// If this instance has non-erasable parameters, it cannot be a shared
// monomorphization. Non-generic instances are already handled above
// by `is_reachable_non_generic()`.
if substs.non_erasable_generics().next().is_none() {
return false;
}
// Take a look at the available monomorphizations listed in the metadata
// of upstream crates.
tcx.upstream_monomorphizations_for(def_id)
.map(|set| set.contains_key(substs))
.unwrap_or(false)
}
}
/// For a given pair of source and target type that occur in an unsizing coercion,