bjoernager/rust
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Auto merge of #121644 - oli-obk:unique_static_innards2, r=RalfJung,nnethercote

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Ensure nested allocations in statics neither get deduplicated nor duplicated

This PR generates new `DefId`s for nested allocations in static items and feeds all the right queries to make the compiler believe these are regular `static` items. I chose this design, because all other designs are fragile and make the compiler horribly complex for such a niche use case.

At present this wrecks incremental compilation performance *in case nested allocations exist* (because any query creating a `DefId` will be recomputed and never loaded from the cache). This will be resolved later in https://github.com/rust-lang/rust/pull/115613 . All other statics are unaffected by this change and will not have performance regressions (heh, famous last words)

This PR contains various smaller refactorings that can be pulled out into separate PRs. It is best reviewed commit-by-commit. The last commit is where the actual magic happens.

r? `@RalfJung` on the const interner and engine changes

fixes https://github.com/rust-lang/rust/issues/79738
This commit is contained in:
bors 2024-03-12 10:29:15 +00:00
commit 3b85d2c7fc
66 changed files with 461 additions and 170 deletions
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4
compiler/rustc_codegen_ssa/src/back/symbol_export.rs
View file

@ -87,7 +87,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> DefIdMap<S
// Only consider nodes that actually have exported symbols.
match tcx.def_kind(def_id) {
DefKind::Fn | DefKind::Static(_) => {}
DefKind::Fn | DefKind::Static { .. } => {}
DefKind::AssocFn if tcx.impl_of_method(def_id.to_def_id()).is_some() => {}
_ => return None,
};
@ -483,7 +483,7 @@ fn symbol_export_level(tcx: TyCtxt<'_>, sym_def_id: DefId) -> SymbolExportLevel
let target = &tcx.sess.target.llvm_target;
// WebAssembly cannot export data symbols, so reduce their export level
if target.contains("emscripten") {
if let DefKind::Static(_) = tcx.def_kind(sym_def_id) {
if let DefKind::Static { .. } = tcx.def_kind(sym_def_id) {
return SymbolExportLevel::Rust;
}
}

2
compiler/rustc_codegen_ssa/src/mono_item.rs
View file

@ -30,7 +30,7 @@ impl<'a, 'tcx: 'a> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {
match *self {
MonoItem::Static(def_id) => {
cx.codegen_static(def_id, cx.tcx().is_mutable_static(def_id));
cx.codegen_static(def_id);
}
MonoItem::GlobalAsm(item_id) => {
let item = cx.tcx().hir().item(item_id);

2
compiler/rustc_codegen_ssa/src/traits/statics.rs
View file

@ -4,7 +4,7 @@ use rustc_target::abi::Align;
pub trait StaticMethods: BackendTypes {
fn static_addr_of(&self, cv: Self::Value, align: Align, kind: Option<&str>) -> Self::Value;
fn codegen_static(&self, def_id: DefId, is_mutable: bool);
fn codegen_static(&self, def_id: DefId);
/// Mark the given global value as "used", to prevent the compiler and linker from potentially
/// removing a static variable that may otherwise appear unused.