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Ensure nested allocations in statics do not get deduplicated

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This commit is contained in:
Oli Scherer 2024-02-26 18:03:06 +00:00
parent 92414ab25d
commit d3514a036d
21 changed files with 259 additions and 54 deletions
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6
compiler/rustc_const_eval/src/const_eval/eval_queries.rs
View file

@ -59,7 +59,7 @@ fn eval_body_using_ecx<'mir, 'tcx>(
};
let ret = if let InternKind::Static(_) = intern_kind {
create_static_alloc(ecx, cid.instance.def_id(), layout)?
create_static_alloc(ecx, cid.instance.def_id().expect_local(), layout)?
} else {
ecx.allocate(layout, MemoryKind::Stack)?
};
@ -380,7 +380,11 @@ pub fn eval_in_interpreter<'mir, 'tcx>(
}
Ok(mplace) => {
// Since evaluation had no errors, validate the resulting constant.
// Temporarily allow access to the static_root_ids for the purpose of validation.
let static_root_ids = ecx.machine.static_root_ids.take();
let res = const_validate_mplace(&ecx, &mplace, cid);
ecx.machine.static_root_ids = static_root_ids;
let alloc_id = mplace.ptr().provenance.unwrap().alloc_id();

11
compiler/rustc_const_eval/src/const_eval/machine.rs
View file

@ -8,6 +8,7 @@ use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::fx::IndexEntry;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::LangItem;
use rustc_middle::mir;
use rustc_middle::mir::AssertMessage;
@ -59,8 +60,10 @@ pub struct CompileTimeInterpreter<'mir, 'tcx> {
/// Whether to check alignment during evaluation.
pub(super) check_alignment: CheckAlignment,
/// Used to prevent reads from a static's base allocation, as that may allow for self-initialization.
pub(crate) static_root_alloc_id: Option<AllocId>,
/// If `Some`, we are evaluating the initializer of the static with the given `LocalDefId`,
/// storing the result in the given `AllocId`.
/// Used to prevent reads from a static's base allocation, as that may allow for self-initialization loops.
pub(crate) static_root_ids: Option<(AllocId, LocalDefId)>,
}
#[derive(Copy, Clone)]
@ -94,7 +97,7 @@ impl<'mir, 'tcx> CompileTimeInterpreter<'mir, 'tcx> {
stack: Vec::new(),
can_access_mut_global,
check_alignment,
static_root_alloc_id: None,
static_root_ids: None,
}
}
}
@ -749,7 +752,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
ecx: &InterpCx<'mir, 'tcx, Self>,
alloc_id: AllocId,
) -> InterpResult<'tcx> {
if Some(alloc_id) == ecx.machine.static_root_alloc_id {
if Some(alloc_id) == ecx.machine.static_root_ids.map(|(id, _)| id) {
Err(ConstEvalErrKind::RecursiveStatic.into())
} else {
Ok(())

47
compiler/rustc_const_eval/src/interpret/intern.rs
View file

@ -13,12 +13,16 @@
//! but that would require relying on type information, and given how many ways Rust has to lie
//! about type information, we want to avoid doing that.
use hir::def::DefKind;
use rustc_ast::Mutability;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
use rustc_middle::mir::interpret::{CtfeProvenance, InterpResult};
use rustc_middle::mir::interpret::{ConstAllocation, CtfeProvenance, InterpResult};
use rustc_middle::query::TyCtxtAt;
use rustc_middle::ty::layout::TyAndLayout;
use rustc_span::def_id::LocalDefId;
use rustc_span::sym;
use super::{AllocId, Allocation, InterpCx, MPlaceTy, Machine, MemoryKind, PlaceTy};
use crate::const_eval;
@ -33,7 +37,19 @@ pub trait CompileTimeMachine<'mir, 'tcx: 'mir, T> = Machine<
FrameExtra = (),
AllocExtra = (),
MemoryMap = FxIndexMap<AllocId, (MemoryKind<T>, Allocation)>,
>;
> + HasStaticRootDefId;
pub trait HasStaticRootDefId {
/// Returns the `DefId` of the static item that is currently being evaluated.
/// Used for interning to be able to handle nested allocations.
fn static_def_id(&self) -> Option<LocalDefId>;
}
impl HasStaticRootDefId for const_eval::CompileTimeInterpreter<'_, '_> {
fn static_def_id(&self) -> Option<LocalDefId> {
Some(self.static_root_ids?.1)
}
}
/// Intern an allocation. Returns `Err` if the allocation does not exist in the local memory.
///
@ -67,10 +83,35 @@ fn intern_shallow<'rt, 'mir, 'tcx, T, M: CompileTimeMachine<'mir, 'tcx, T>>(
}
// link the alloc id to the actual allocation
let alloc = ecx.tcx.mk_const_alloc(alloc);
ecx.tcx.set_alloc_id_memory(alloc_id, alloc);
if let Some(static_id) = ecx.machine.static_def_id() {
intern_as_new_static(ecx.tcx, static_id, alloc_id, alloc);
} else {
ecx.tcx.set_alloc_id_memory(alloc_id, alloc);
}
Ok(alloc.0.0.provenance().ptrs().iter().map(|&(_, prov)| prov))
}
/// Creates a new `DefId` and feeds all the right queries to make this `DefId`
/// appear as if it were a user-written `static` (though it has no HIR).
fn intern_as_new_static<'tcx>(
tcx: TyCtxtAt<'tcx>,
static_id: LocalDefId,
alloc_id: AllocId,
alloc: ConstAllocation<'tcx>,
) {
let feed = tcx.create_def(
static_id,
sym::nested,
DefKind::Static { mt: alloc.0.mutability, nested: true },
);
tcx.set_nested_alloc_id_static(alloc_id, feed.def_id());
feed.codegen_fn_attrs(tcx.codegen_fn_attrs(static_id).clone());
feed.eval_static_initializer(Ok(alloc));
feed.generics_of(tcx.generics_of(static_id).clone());
feed.def_ident_span(tcx.def_ident_span(static_id));
feed.explicit_predicates_of(tcx.explicit_predicates_of(static_id));
}
/// How a constant value should be interned.
#[derive(Copy, Clone, Debug, PartialEq, Hash, Eq)]
pub enum InternKind {

38
compiler/rustc_const_eval/src/interpret/memory.rs
View file

@ -15,6 +15,7 @@ use std::ptr;
use rustc_ast::Mutability;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
use rustc_hir::def::DefKind;
use rustc_middle::mir::display_allocation;
use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TyCtxt};
use rustc_target::abi::{Align, HasDataLayout, Size};
@ -761,19 +762,36 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// be held throughout the match.
match self.tcx.try_get_global_alloc(id) {
Some(GlobalAlloc::Static(def_id)) => {
assert!(self.tcx.is_static(def_id));
// Thread-local statics do not have a constant address. They *must* be accessed via
// `ThreadLocalRef`; we can never have a pointer to them as a regular constant value.
assert!(!self.tcx.is_thread_local_static(def_id));
// Use size and align of the type.
let ty = self
.tcx
.type_of(def_id)
.no_bound_vars()
.expect("statics should not have generic parameters");
let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
assert!(layout.is_sized());
(layout.size, layout.align.abi, AllocKind::LiveData)
let DefKind::Static { nested, .. } = self.tcx.def_kind(def_id) else {
bug!("GlobalAlloc::Static is not a static")
};
let (size, align) = if nested {
// Nested anonymous statics are untyped, so let's get their
// size and alignment from the allocaiton itself. This always
// succeeds, as the query is fed at DefId creation time, so no
// evaluation actually occurs.
let alloc = self.tcx.eval_static_initializer(def_id).unwrap();
(alloc.0.size(), alloc.0.align)
} else {
// Use size and align of the type for everything else. We need
// to do that to
// * avoid cycle errors in case of self-referential statics,
// * be able to get information on extern statics.
let ty = self
.tcx
.type_of(def_id)
.no_bound_vars()
.expect("statics should not have generic parameters");
let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
assert!(layout.is_sized());
(layout.size, layout.align.abi)
};
(size, align, AllocKind::LiveData)
}
Some(GlobalAlloc::Memory(alloc)) => {
// Need to duplicate the logic here, because the global allocations have

2
compiler/rustc_const_eval/src/interpret/mod.rs
View file

@ -22,7 +22,7 @@ pub use rustc_middle::mir::interpret::*; // have all the `interpret` symbols in
pub use self::eval_context::{format_interp_error, Frame, FrameInfo, InterpCx, StackPopCleanup};
pub use self::intern::{
intern_const_alloc_for_constprop, intern_const_alloc_recursive, InternKind,
intern_const_alloc_for_constprop, intern_const_alloc_recursive, HasStaticRootDefId, InternKind,
};
pub use self::machine::{compile_time_machine, AllocMap, Machine, MayLeak, StackPopJump};
pub use self::memory::{AllocKind, AllocRef, AllocRefMut, FnVal, Memory, MemoryKind};

10
compiler/rustc_const_eval/src/interpret/util.rs
View file

@ -1,11 +1,11 @@
use crate::const_eval::CompileTimeEvalContext;
use crate::interpret::{MemPlaceMeta, MemoryKind};
use rustc_hir::def_id::LocalDefId;
use rustc_middle::mir::interpret::{AllocId, Allocation, InterpResult, Pointer};
use rustc_middle::ty::layout::TyAndLayout;
use rustc_middle::ty::{
self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
};
use rustc_span::def_id::DefId;
use std::ops::ControlFlow;
use super::MPlaceTy;
@ -89,13 +89,13 @@ pub(crate) fn take_static_root_alloc<'mir, 'tcx: 'mir>(
pub(crate) fn create_static_alloc<'mir, 'tcx: 'mir>(
ecx: &mut CompileTimeEvalContext<'mir, 'tcx>,
static_def_id: DefId,
static_def_id: LocalDefId,
layout: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, MPlaceTy<'tcx>> {
let alloc = Allocation::try_uninit(layout.size, layout.align.abi)?;
let alloc_id = ecx.tcx.reserve_and_set_static_alloc(static_def_id);
assert_eq!(ecx.machine.static_root_alloc_id, None);
ecx.machine.static_root_alloc_id = Some(alloc_id);
let alloc_id = ecx.tcx.reserve_and_set_static_alloc(static_def_id.into());
assert_eq!(ecx.machine.static_root_ids, None);
ecx.machine.static_root_ids = Some((alloc_id, static_def_id));
assert!(ecx.memory.alloc_map.insert(alloc_id, (MemoryKind::Stack, alloc)).is_none());
Ok(ecx.ptr_with_meta_to_mplace(Pointer::from(alloc_id).into(), MemPlaceMeta::None, layout))
}

32
compiler/rustc_const_eval/src/interpret/validity.rs
View file

@ -457,16 +457,6 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
// Special handling for pointers to statics (irrespective of their type).
assert!(!self.ecx.tcx.is_thread_local_static(did));
assert!(self.ecx.tcx.is_static(did));
let is_mut = matches!(
self.ecx.tcx.def_kind(did),
DefKind::Static { mt: Mutability::Mut, .. }
) || !self
.ecx
.tcx
.type_of(did)
.no_bound_vars()
.expect("statics should not have generic parameters")
.is_freeze(*self.ecx.tcx, ty::ParamEnv::reveal_all());
// Mode-specific checks
match self.ctfe_mode {
Some(
@ -491,8 +481,26 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
}
None => {}
}
// Return alloc mutability
if is_mut { Mutability::Mut } else { Mutability::Not }
// Return alloc mutability. For "root" statics we look at the type to account for interior
// mutability; for nested statics we have no type and directly use the annotated mutability.
match self.ecx.tcx.def_kind(did) {
DefKind::Static { mt: Mutability::Mut, .. } => Mutability::Mut,
DefKind::Static { mt: Mutability::Not, nested: true } => {
Mutability::Not
}
DefKind::Static { mt: Mutability::Not, nested: false }
if !self
.ecx
.tcx
.type_of(did)
.no_bound_vars()
.expect("statics should not have generic parameters")
.is_freeze(*self.ecx.tcx, ty::ParamEnv::reveal_all()) =>
{
Mutability::Mut
}
_ => Mutability::Not,
}
}
GlobalAlloc::Memory(alloc) => alloc.inner().mutability,
GlobalAlloc::Function(..) | GlobalAlloc::VTable(..) => {