908 lines
38 KiB
Rust
908 lines
38 KiB
Rust
use std::borrow::{Borrow, Cow};
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use std::fmt;
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use std::hash::Hash;
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use rustc_abi::{Align, Size};
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use rustc_ast::Mutability;
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use rustc_data_structures::fx::{FxHashMap, FxIndexMap, IndexEntry};
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use rustc_errors::msg;
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use rustc_hir::attrs::AttributeKind;
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use rustc_hir::def_id::{DefId, LocalDefId};
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use rustc_hir::{self as hir, CRATE_HIR_ID, LangItem, find_attr};
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use rustc_middle::mir::AssertMessage;
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use rustc_middle::mir::interpret::ReportedErrorInfo;
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use rustc_middle::query::TyCtxtAt;
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use rustc_middle::ty::layout::{HasTypingEnv, TyAndLayout, ValidityRequirement};
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use rustc_middle::ty::{self, Ty, TyCtxt};
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use rustc_middle::{bug, mir};
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use rustc_span::{Span, Symbol, sym};
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use rustc_target::callconv::FnAbi;
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use tracing::debug;
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use super::error::*;
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use crate::errors::{LongRunning, LongRunningWarn};
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use crate::interpret::{
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self, AllocId, AllocInit, AllocRange, ConstAllocation, CtfeProvenance, FnArg, Frame,
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GlobalAlloc, ImmTy, InterpCx, InterpResult, OpTy, PlaceTy, Pointer, RangeSet, Scalar,
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compile_time_machine, err_inval, interp_ok, throw_exhaust, throw_inval, throw_ub,
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throw_ub_custom, throw_unsup, throw_unsup_format,
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};
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/// When hitting this many interpreted terminators we emit a deny by default lint
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/// that notfies the user that their constant takes a long time to evaluate. If that's
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/// what they intended, they can just allow the lint.
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const LINT_TERMINATOR_LIMIT: usize = 2_000_000;
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/// The limit used by `-Z tiny-const-eval-limit`. This smaller limit is useful for internal
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/// tests not needing to run 30s or more to show some behaviour.
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const TINY_LINT_TERMINATOR_LIMIT: usize = 20;
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/// After this many interpreted terminators, we start emitting progress indicators at every
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/// power of two of interpreted terminators.
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const PROGRESS_INDICATOR_START: usize = 4_000_000;
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/// Extra machine state for CTFE, and the Machine instance.
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//
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// Should be public because out-of-tree rustc consumers need this
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// if they want to interact with constant values.
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pub struct CompileTimeMachine<'tcx> {
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/// The number of terminators that have been evaluated.
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///
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/// This is used to produce lints informing the user that the compiler is not stuck.
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/// Set to `usize::MAX` to never report anything.
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pub(super) num_evaluated_steps: usize,
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/// The virtual call stack.
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pub(super) stack: Vec<Frame<'tcx>>,
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/// Pattern matching on consts with references would be unsound if those references
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/// could point to anything mutable. Therefore, when evaluating consts and when constructing valtrees,
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/// we ensure that only immutable global memory can be accessed.
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pub(super) can_access_mut_global: CanAccessMutGlobal,
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/// Whether to check alignment during evaluation.
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pub(super) check_alignment: CheckAlignment,
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/// If `Some`, we are evaluating the initializer of the static with the given `LocalDefId`,
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/// storing the result in the given `AllocId`.
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/// Used to prevent accesses to a static's base allocation, as that may allow for self-initialization loops.
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pub(crate) static_root_ids: Option<(AllocId, LocalDefId)>,
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/// A cache of "data range" computations for unions (i.e., the offsets of non-padding bytes).
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union_data_ranges: FxHashMap<Ty<'tcx>, RangeSet>,
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}
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#[derive(Copy, Clone)]
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pub enum CheckAlignment {
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/// Ignore all alignment requirements.
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/// This is mainly used in interning.
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No,
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/// Hard error when dereferencing a misaligned pointer.
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Error,
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}
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#[derive(Copy, Clone, PartialEq)]
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pub(crate) enum CanAccessMutGlobal {
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No,
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Yes,
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}
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impl From<bool> for CanAccessMutGlobal {
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fn from(value: bool) -> Self {
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if value { Self::Yes } else { Self::No }
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}
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}
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impl<'tcx> CompileTimeMachine<'tcx> {
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pub(crate) fn new(
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can_access_mut_global: CanAccessMutGlobal,
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check_alignment: CheckAlignment,
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) -> Self {
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CompileTimeMachine {
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num_evaluated_steps: 0,
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stack: Vec::new(),
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can_access_mut_global,
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check_alignment,
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static_root_ids: None,
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union_data_ranges: FxHashMap::default(),
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}
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}
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}
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impl<K: Hash + Eq, V> interpret::AllocMap<K, V> for FxIndexMap<K, V> {
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#[inline(always)]
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fn contains_key<Q: ?Sized + Hash + Eq>(&mut self, k: &Q) -> bool
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where
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K: Borrow<Q>,
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{
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FxIndexMap::contains_key(self, k)
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}
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#[inline(always)]
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fn contains_key_ref<Q: ?Sized + Hash + Eq>(&self, k: &Q) -> bool
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where
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K: Borrow<Q>,
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{
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FxIndexMap::contains_key(self, k)
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}
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#[inline(always)]
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fn insert(&mut self, k: K, v: V) -> Option<V> {
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FxIndexMap::insert(self, k, v)
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}
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#[inline(always)]
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fn remove<Q: ?Sized + Hash + Eq>(&mut self, k: &Q) -> Option<V>
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where
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K: Borrow<Q>,
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{
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// FIXME(#120456) - is `swap_remove` correct?
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FxIndexMap::swap_remove(self, k)
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}
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#[inline(always)]
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fn filter_map_collect<T>(&self, mut f: impl FnMut(&K, &V) -> Option<T>) -> Vec<T> {
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self.iter().filter_map(move |(k, v)| f(k, v)).collect()
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}
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#[inline(always)]
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fn get_or<E>(&self, k: K, vacant: impl FnOnce() -> Result<V, E>) -> Result<&V, E> {
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match self.get(&k) {
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Some(v) => Ok(v),
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None => {
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vacant()?;
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bug!("The CTFE machine shouldn't ever need to extend the alloc_map when reading")
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}
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}
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}
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#[inline(always)]
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fn get_mut_or<E>(&mut self, k: K, vacant: impl FnOnce() -> Result<V, E>) -> Result<&mut V, E> {
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match self.entry(k) {
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IndexEntry::Occupied(e) => Ok(e.into_mut()),
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IndexEntry::Vacant(e) => {
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let v = vacant()?;
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Ok(e.insert(v))
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}
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}
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}
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}
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pub type CompileTimeInterpCx<'tcx> = InterpCx<'tcx, CompileTimeMachine<'tcx>>;
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#[derive(Debug, PartialEq, Eq, Copy, Clone)]
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pub enum MemoryKind {
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Heap {
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/// Indicates whether `make_global` was called on this allocation.
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/// If this is `true`, the allocation must be immutable.
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was_made_global: bool,
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},
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}
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impl fmt::Display for MemoryKind {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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match self {
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MemoryKind::Heap { was_made_global } => {
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write!(f, "heap allocation{}", if *was_made_global { " (made global)" } else { "" })
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}
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}
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}
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}
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impl interpret::MayLeak for MemoryKind {
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#[inline(always)]
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fn may_leak(self) -> bool {
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match self {
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MemoryKind::Heap { was_made_global } => was_made_global,
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}
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}
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}
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impl interpret::MayLeak for ! {
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#[inline(always)]
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fn may_leak(self) -> bool {
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// `self` is uninhabited
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self
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}
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}
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impl<'tcx> CompileTimeInterpCx<'tcx> {
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fn location_triple_for_span(&self, span: Span) -> (Symbol, u32, u32) {
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let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
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let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());
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use rustc_span::RemapPathScopeComponents;
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(
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Symbol::intern(
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&caller.file.name.display(RemapPathScopeComponents::DIAGNOSTICS).to_string_lossy(),
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),
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u32::try_from(caller.line).unwrap(),
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u32::try_from(caller.col_display).unwrap().checked_add(1).unwrap(),
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)
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}
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/// "Intercept" a function call, because we have something special to do for it.
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/// All `#[rustc_do_not_const_check]` functions MUST be hooked here.
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/// If this returns `Some` function, which may be `instance` or a different function with
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/// compatible arguments, then evaluation should continue with that function.
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/// If this returns `None`, the function call has been handled and the function has returned.
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fn hook_special_const_fn(
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&mut self,
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instance: ty::Instance<'tcx>,
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args: &[FnArg<'tcx>],
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_dest: &PlaceTy<'tcx>,
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_ret: Option<mir::BasicBlock>,
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) -> InterpResult<'tcx, Option<ty::Instance<'tcx>>> {
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let def_id = instance.def_id();
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if self.tcx.is_lang_item(def_id, LangItem::PanicDisplay)
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|| self.tcx.is_lang_item(def_id, LangItem::BeginPanic)
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{
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let args = Self::copy_fn_args(args);
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// &str or &&str
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assert!(args.len() == 1);
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let mut msg_place = self.deref_pointer(&args[0])?;
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while msg_place.layout.ty.is_ref() {
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msg_place = self.deref_pointer(&msg_place)?;
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}
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let msg = Symbol::intern(self.read_str(&msg_place)?);
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let span = self.find_closest_untracked_caller_location();
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let (file, line, col) = self.location_triple_for_span(span);
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return Err(ConstEvalErrKind::Panic { msg, file, line, col }).into();
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} else if self.tcx.is_lang_item(def_id, LangItem::PanicFmt) {
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// For panic_fmt, call const_panic_fmt instead.
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let const_def_id = self.tcx.require_lang_item(LangItem::ConstPanicFmt, self.tcx.span);
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let new_instance = ty::Instance::expect_resolve(
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*self.tcx,
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self.typing_env(),
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const_def_id,
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instance.args,
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self.cur_span(),
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);
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return interp_ok(Some(new_instance));
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}
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interp_ok(Some(instance))
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}
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/// See documentation on the `ptr_guaranteed_cmp` intrinsic.
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/// Returns `2` if the result is unknown.
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/// Returns `1` if the pointers are guaranteed equal.
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/// Returns `0` if the pointers are guaranteed inequal.
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///
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/// Note that this intrinsic is exposed on stable for comparison with null. In other words, any
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/// change to this function that affects comparison with null is insta-stable!
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fn guaranteed_cmp(&mut self, a: Scalar, b: Scalar) -> InterpResult<'tcx, u8> {
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interp_ok(match (a, b) {
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// Comparisons between integers are always known.
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(Scalar::Int(a), Scalar::Int(b)) => (a == b) as u8,
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// Comparing a pointer `ptr` with an integer `int` is equivalent to comparing
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// `ptr-int` with null, so we can reduce this case to a `scalar_may_be_null` test.
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(Scalar::Int(int), Scalar::Ptr(ptr, _)) | (Scalar::Ptr(ptr, _), Scalar::Int(int)) => {
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let int = int.to_target_usize(*self.tcx);
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// The `wrapping_neg` here may produce a value that is not
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// a valid target usize any more... but `wrapping_offset` handles that correctly.
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let offset_ptr = ptr.wrapping_offset(Size::from_bytes(int.wrapping_neg()), self);
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if !self.scalar_may_be_null(Scalar::from_pointer(offset_ptr, self))? {
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// `ptr.wrapping_sub(int)` is definitely not equal to `0`, so `ptr != int`
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0
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} else {
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// `ptr.wrapping_sub(int)` could be equal to `0`, but might not be,
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// so we cannot know for sure if `ptr == int` or not
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2
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}
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}
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(Scalar::Ptr(a, _), Scalar::Ptr(b, _)) => {
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let (a_prov, a_offset) = a.prov_and_relative_offset();
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let (b_prov, b_offset) = b.prov_and_relative_offset();
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let a_allocid = a_prov.alloc_id();
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let b_allocid = b_prov.alloc_id();
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let a_info = self.get_alloc_info(a_allocid);
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let b_info = self.get_alloc_info(b_allocid);
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// Check if the pointers cannot be equal due to alignment
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if a_info.align > Align::ONE && b_info.align > Align::ONE {
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let min_align = Ord::min(a_info.align.bytes(), b_info.align.bytes());
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let a_residue = a_offset.bytes() % min_align;
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let b_residue = b_offset.bytes() % min_align;
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if a_residue != b_residue {
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// If the two pointers have a different residue modulo their
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// common alignment, they cannot be equal.
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return interp_ok(0);
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}
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// The pointers have the same residue modulo their common alignment,
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// so they could be equal. Try the other checks.
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}
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if let (Some(GlobalAlloc::Static(a_did)), Some(GlobalAlloc::Static(b_did))) = (
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self.tcx.try_get_global_alloc(a_allocid),
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self.tcx.try_get_global_alloc(b_allocid),
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) {
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if a_allocid == b_allocid {
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debug_assert_eq!(
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a_did, b_did,
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"different static item DefIds had same AllocId? {a_allocid:?} == {b_allocid:?}, {a_did:?} != {b_did:?}"
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);
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// Comparing two pointers into the same static. As per
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// https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.intro
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// a static cannot be duplicated, so if two pointers are into the same
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// static, they are equal if and only if their offsets are equal.
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(a_offset == b_offset) as u8
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} else {
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debug_assert_ne!(
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a_did, b_did,
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"same static item DefId had two different AllocIds? {a_allocid:?} != {b_allocid:?}, {a_did:?} == {b_did:?}"
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);
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// Comparing two pointers into the different statics.
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// We can never determine for sure that two pointers into different statics
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// are *equal*, but we can know that they are *inequal* if they are both
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// strictly in-bounds (i.e. in-bounds and not one-past-the-end) of
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// their respective static, as different non-zero-sized statics cannot
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// overlap or be deduplicated as per
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// https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.intro
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// (non-deduplication), and
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// https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.storage-disjointness
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// (non-overlapping).
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if a_offset < a_info.size && b_offset < b_info.size {
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0
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} else {
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// Otherwise, conservatively say we don't know.
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// There are some cases we could still return `0` for, e.g.
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// if the pointers being equal would require their statics to overlap
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// one or more bytes, but for simplicity we currently only check
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// strictly in-bounds pointers.
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2
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}
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}
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} else {
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// All other cases we conservatively say we don't know.
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//
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// For comparing statics to non-statics, as per https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.storage-disjointness
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// immutable statics can overlap with other kinds of allocations sometimes.
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//
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// FIXME: We could be more decisive for (non-zero-sized) mutable statics,
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// which cannot overlap with other kinds of allocations.
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//
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// Functions and vtables can be duplicated and deduplicated, so we
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// cannot be sure of runtime equality of pointers to the same one, or the
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// runtime inequality of pointers to different ones (see e.g. #73722),
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// so comparing those should return 2, whether they are the same allocation
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// or not.
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//
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// `GlobalAlloc::TypeId` exists mostly to prevent consteval from comparing
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// `TypeId`s, so comparing those should always return 2, whether they are the
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// same allocation or not.
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//
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// FIXME: We could revisit comparing pointers into the same
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// `GlobalAlloc::Memory` once https://github.com/rust-lang/rust/issues/128775
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// is fixed (but they can be deduplicated, so comparing pointers into different
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// ones should return 2).
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2
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}
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}
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})
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}
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}
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impl<'tcx> CompileTimeMachine<'tcx> {
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#[inline(always)]
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/// Find the first stack frame that is within the current crate, if any.
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/// Otherwise, return the crate's HirId
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pub fn best_lint_scope(&self, tcx: TyCtxt<'tcx>) -> hir::HirId {
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self.stack.iter().find_map(|frame| frame.lint_root(tcx)).unwrap_or(CRATE_HIR_ID)
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}
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}
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impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
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compile_time_machine!(<'tcx>);
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const PANIC_ON_ALLOC_FAIL: bool = false; // will be raised as a proper error
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#[inline(always)]
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fn enforce_alignment(ecx: &InterpCx<'tcx, Self>) -> bool {
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matches!(ecx.machine.check_alignment, CheckAlignment::Error)
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}
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#[inline(always)]
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fn enforce_validity(ecx: &InterpCx<'tcx, Self>, layout: TyAndLayout<'tcx>) -> bool {
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ecx.tcx.sess.opts.unstable_opts.extra_const_ub_checks || layout.is_uninhabited()
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}
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fn load_mir(
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ecx: &InterpCx<'tcx, Self>,
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instance: ty::InstanceKind<'tcx>,
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) -> &'tcx mir::Body<'tcx> {
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match instance {
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ty::InstanceKind::Item(def) => ecx.tcx.mir_for_ctfe(def),
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_ => ecx.tcx.instance_mir(instance),
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}
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}
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fn find_mir_or_eval_fn(
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ecx: &mut InterpCx<'tcx, Self>,
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orig_instance: ty::Instance<'tcx>,
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_abi: &FnAbi<'tcx, Ty<'tcx>>,
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args: &[FnArg<'tcx>],
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dest: &PlaceTy<'tcx>,
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ret: Option<mir::BasicBlock>,
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_unwind: mir::UnwindAction, // unwinding is not supported in consts
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) -> InterpResult<'tcx, Option<(&'tcx mir::Body<'tcx>, ty::Instance<'tcx>)>> {
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debug!("find_mir_or_eval_fn: {:?}", orig_instance);
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// Replace some functions.
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let Some(instance) = ecx.hook_special_const_fn(orig_instance, args, dest, ret)? else {
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// Call has already been handled.
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return interp_ok(None);
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};
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// Only check non-glue functions
|
|
if let ty::InstanceKind::Item(def) = instance.def {
|
|
// Execution might have wandered off into other crates, so we cannot do a stability-
|
|
// sensitive check here. But we can at least rule out functions that are not const at
|
|
// all. That said, we have to allow calling functions inside a `const trait`. These
|
|
// *are* const-checked!
|
|
if !ecx.tcx.is_const_fn(def)
|
|
|| find_attr!(ecx.tcx.get_all_attrs(def), AttributeKind::RustcDoNotConstCheck)
|
|
{
|
|
// We certainly do *not* want to actually call the fn
|
|
// though, so be sure we return here.
|
|
throw_unsup_format!("calling non-const function `{}`", instance)
|
|
}
|
|
}
|
|
|
|
// This is a const fn. Call it.
|
|
// In case of replacement, we return the *original* instance to make backtraces work out
|
|
// (and we hope this does not confuse the FnAbi checks too much).
|
|
interp_ok(Some((ecx.load_mir(instance.def, None)?, orig_instance)))
|
|
}
|
|
|
|
fn panic_nounwind(ecx: &mut InterpCx<'tcx, Self>, msg: &str) -> InterpResult<'tcx> {
|
|
let msg = Symbol::intern(msg);
|
|
let span = ecx.find_closest_untracked_caller_location();
|
|
let (file, line, col) = ecx.location_triple_for_span(span);
|
|
Err(ConstEvalErrKind::Panic { msg, file, line, col }).into()
|
|
}
|
|
|
|
fn call_intrinsic(
|
|
ecx: &mut InterpCx<'tcx, Self>,
|
|
instance: ty::Instance<'tcx>,
|
|
args: &[OpTy<'tcx>],
|
|
dest: &PlaceTy<'tcx, Self::Provenance>,
|
|
target: Option<mir::BasicBlock>,
|
|
_unwind: mir::UnwindAction,
|
|
) -> InterpResult<'tcx, Option<ty::Instance<'tcx>>> {
|
|
// Shared intrinsics.
|
|
if ecx.eval_intrinsic(instance, args, dest, target)? {
|
|
return interp_ok(None);
|
|
}
|
|
let intrinsic_name = ecx.tcx.item_name(instance.def_id());
|
|
|
|
// CTFE-specific intrinsics.
|
|
match intrinsic_name {
|
|
sym::ptr_guaranteed_cmp => {
|
|
let a = ecx.read_scalar(&args[0])?;
|
|
let b = ecx.read_scalar(&args[1])?;
|
|
let cmp = ecx.guaranteed_cmp(a, b)?;
|
|
ecx.write_scalar(Scalar::from_u8(cmp), dest)?;
|
|
}
|
|
sym::const_allocate => {
|
|
let size = ecx.read_scalar(&args[0])?.to_target_usize(ecx)?;
|
|
let align = ecx.read_scalar(&args[1])?.to_target_usize(ecx)?;
|
|
|
|
let align = match Align::from_bytes(align) {
|
|
Ok(a) => a,
|
|
Err(err) => throw_ub_custom!(
|
|
msg!(
|
|
"invalid align passed to `{$name}`: {$align} is {$err_kind ->
|
|
[not_power_of_two] not a power of 2
|
|
[too_large] too large
|
|
*[other] {\"\"}
|
|
}"
|
|
),
|
|
name = "const_allocate",
|
|
err_kind = err.diag_ident(),
|
|
align = err.align()
|
|
),
|
|
};
|
|
|
|
let ptr = ecx.allocate_ptr(
|
|
Size::from_bytes(size),
|
|
align,
|
|
interpret::MemoryKind::Machine(MemoryKind::Heap { was_made_global: false }),
|
|
AllocInit::Uninit,
|
|
)?;
|
|
ecx.write_pointer(ptr, dest)?;
|
|
}
|
|
sym::const_deallocate => {
|
|
let ptr = ecx.read_pointer(&args[0])?;
|
|
let size = ecx.read_scalar(&args[1])?.to_target_usize(ecx)?;
|
|
let align = ecx.read_scalar(&args[2])?.to_target_usize(ecx)?;
|
|
|
|
let size = Size::from_bytes(size);
|
|
let align = match Align::from_bytes(align) {
|
|
Ok(a) => a,
|
|
Err(err) => throw_ub_custom!(
|
|
msg!(
|
|
"invalid align passed to `{$name}`: {$align} is {$err_kind ->
|
|
[not_power_of_two] not a power of 2
|
|
[too_large] too large
|
|
*[other] {\"\"}
|
|
}"
|
|
),
|
|
name = "const_deallocate",
|
|
err_kind = err.diag_ident(),
|
|
align = err.align()
|
|
),
|
|
};
|
|
|
|
// If an allocation is created in an another const,
|
|
// we don't deallocate it.
|
|
let (alloc_id, _, _) = ecx.ptr_get_alloc_id(ptr, 0)?;
|
|
let is_allocated_in_another_const = matches!(
|
|
ecx.tcx.try_get_global_alloc(alloc_id),
|
|
Some(interpret::GlobalAlloc::Memory(_))
|
|
);
|
|
|
|
if !is_allocated_in_another_const {
|
|
ecx.deallocate_ptr(
|
|
ptr,
|
|
Some((size, align)),
|
|
interpret::MemoryKind::Machine(MemoryKind::Heap { was_made_global: false }),
|
|
)?;
|
|
}
|
|
}
|
|
|
|
sym::const_make_global => {
|
|
let ptr = ecx.read_pointer(&args[0])?;
|
|
ecx.make_const_heap_ptr_global(ptr)?;
|
|
ecx.write_pointer(ptr, dest)?;
|
|
}
|
|
|
|
// The intrinsic represents whether the value is known to the optimizer (LLVM).
|
|
// We're not doing any optimizations here, so there is no optimizer that could know the value.
|
|
// (We know the value here in the machine of course, but this is the runtime of that code,
|
|
// not the optimization stage.)
|
|
sym::is_val_statically_known => ecx.write_scalar(Scalar::from_bool(false), dest)?,
|
|
|
|
// We handle these here since Miri does not want to have them.
|
|
sym::assert_inhabited
|
|
| sym::assert_zero_valid
|
|
| sym::assert_mem_uninitialized_valid => {
|
|
let ty = instance.args.type_at(0);
|
|
let requirement = ValidityRequirement::from_intrinsic(intrinsic_name).unwrap();
|
|
|
|
let should_panic = !ecx
|
|
.tcx
|
|
.check_validity_requirement((requirement, ecx.typing_env().as_query_input(ty)))
|
|
.map_err(|_| err_inval!(TooGeneric))?;
|
|
|
|
if should_panic {
|
|
let layout = ecx.layout_of(ty)?;
|
|
|
|
let msg = match requirement {
|
|
// For *all* intrinsics we first check `is_uninhabited` to give a more specific
|
|
// error message.
|
|
_ if layout.is_uninhabited() => format!(
|
|
"aborted execution: attempted to instantiate uninhabited type `{ty}`"
|
|
),
|
|
ValidityRequirement::Inhabited => bug!("handled earlier"),
|
|
ValidityRequirement::Zero => format!(
|
|
"aborted execution: attempted to zero-initialize type `{ty}`, which is invalid"
|
|
),
|
|
ValidityRequirement::UninitMitigated0x01Fill => format!(
|
|
"aborted execution: attempted to leave type `{ty}` uninitialized, which is invalid"
|
|
),
|
|
ValidityRequirement::Uninit => bug!("assert_uninit_valid doesn't exist"),
|
|
};
|
|
|
|
Self::panic_nounwind(ecx, &msg)?;
|
|
// Skip the `return_to_block` at the end (we panicked, we do not return).
|
|
return interp_ok(None);
|
|
}
|
|
}
|
|
|
|
sym::type_of => {
|
|
let ty = ecx.read_type_id(&args[0])?;
|
|
ecx.write_type_info(ty, dest)?;
|
|
}
|
|
|
|
_ => {
|
|
// We haven't handled the intrinsic, let's see if we can use a fallback body.
|
|
if ecx.tcx.intrinsic(instance.def_id()).unwrap().must_be_overridden {
|
|
throw_unsup_format!(
|
|
"intrinsic `{intrinsic_name}` is not supported at compile-time"
|
|
);
|
|
}
|
|
return interp_ok(Some(ty::Instance {
|
|
def: ty::InstanceKind::Item(instance.def_id()),
|
|
args: instance.args,
|
|
}));
|
|
}
|
|
}
|
|
|
|
// Intrinsic is done, jump to next block.
|
|
ecx.return_to_block(target)?;
|
|
interp_ok(None)
|
|
}
|
|
|
|
fn assert_panic(
|
|
ecx: &mut InterpCx<'tcx, Self>,
|
|
msg: &AssertMessage<'tcx>,
|
|
_unwind: mir::UnwindAction,
|
|
) -> InterpResult<'tcx> {
|
|
use rustc_middle::mir::AssertKind::*;
|
|
// Convert `AssertKind<Operand>` to `AssertKind<Scalar>`.
|
|
let eval_to_int =
|
|
|op| ecx.read_immediate(&ecx.eval_operand(op, None)?).map(|x| x.to_const_int());
|
|
let err = match msg {
|
|
BoundsCheck { len, index } => {
|
|
let len = eval_to_int(len)?;
|
|
let index = eval_to_int(index)?;
|
|
BoundsCheck { len, index }
|
|
}
|
|
Overflow(op, l, r) => Overflow(*op, eval_to_int(l)?, eval_to_int(r)?),
|
|
OverflowNeg(op) => OverflowNeg(eval_to_int(op)?),
|
|
DivisionByZero(op) => DivisionByZero(eval_to_int(op)?),
|
|
RemainderByZero(op) => RemainderByZero(eval_to_int(op)?),
|
|
ResumedAfterReturn(coroutine_kind) => ResumedAfterReturn(*coroutine_kind),
|
|
ResumedAfterPanic(coroutine_kind) => ResumedAfterPanic(*coroutine_kind),
|
|
ResumedAfterDrop(coroutine_kind) => ResumedAfterDrop(*coroutine_kind),
|
|
MisalignedPointerDereference { required, found } => MisalignedPointerDereference {
|
|
required: eval_to_int(required)?,
|
|
found: eval_to_int(found)?,
|
|
},
|
|
NullPointerDereference => NullPointerDereference,
|
|
InvalidEnumConstruction(source) => InvalidEnumConstruction(eval_to_int(source)?),
|
|
};
|
|
Err(ConstEvalErrKind::AssertFailure(err)).into()
|
|
}
|
|
|
|
#[inline(always)]
|
|
fn runtime_checks(
|
|
_ecx: &InterpCx<'tcx, Self>,
|
|
_r: mir::RuntimeChecks,
|
|
) -> InterpResult<'tcx, bool> {
|
|
// We can't look at `tcx.sess` here as that can differ across crates, which can lead to
|
|
// unsound differences in evaluating the same constant at different instantiation sites.
|
|
interp_ok(true)
|
|
}
|
|
|
|
fn binary_ptr_op(
|
|
_ecx: &InterpCx<'tcx, Self>,
|
|
_bin_op: mir::BinOp,
|
|
_left: &ImmTy<'tcx>,
|
|
_right: &ImmTy<'tcx>,
|
|
) -> InterpResult<'tcx, ImmTy<'tcx>> {
|
|
throw_unsup_format!("pointer arithmetic or comparison is not supported at compile-time");
|
|
}
|
|
|
|
fn increment_const_eval_counter(ecx: &mut InterpCx<'tcx, Self>) -> InterpResult<'tcx> {
|
|
// The step limit has already been hit in a previous call to `increment_const_eval_counter`.
|
|
|
|
if let Some(new_steps) = ecx.machine.num_evaluated_steps.checked_add(1) {
|
|
let (limit, start) = if ecx.tcx.sess.opts.unstable_opts.tiny_const_eval_limit {
|
|
(TINY_LINT_TERMINATOR_LIMIT, TINY_LINT_TERMINATOR_LIMIT)
|
|
} else {
|
|
(LINT_TERMINATOR_LIMIT, PROGRESS_INDICATOR_START)
|
|
};
|
|
|
|
ecx.machine.num_evaluated_steps = new_steps;
|
|
// By default, we have a *deny* lint kicking in after some time
|
|
// to ensure `loop {}` doesn't just go forever.
|
|
// In case that lint got reduced, in particular for `--cap-lint` situations, we also
|
|
// have a hard warning shown every now and then for really long executions.
|
|
if new_steps == limit {
|
|
// By default, we stop after a million steps, but the user can disable this lint
|
|
// to be able to run until the heat death of the universe or power loss, whichever
|
|
// comes first.
|
|
let hir_id = ecx.machine.best_lint_scope(*ecx.tcx);
|
|
let is_error = ecx
|
|
.tcx
|
|
.lint_level_at_node(
|
|
rustc_session::lint::builtin::LONG_RUNNING_CONST_EVAL,
|
|
hir_id,
|
|
)
|
|
.level
|
|
.is_error();
|
|
let span = ecx.cur_span();
|
|
ecx.tcx.emit_node_span_lint(
|
|
rustc_session::lint::builtin::LONG_RUNNING_CONST_EVAL,
|
|
hir_id,
|
|
span,
|
|
LongRunning { item_span: ecx.tcx.span },
|
|
);
|
|
// If this was a hard error, don't bother continuing evaluation.
|
|
if is_error {
|
|
let guard = ecx
|
|
.tcx
|
|
.dcx()
|
|
.span_delayed_bug(span, "The deny lint should have already errored");
|
|
throw_inval!(AlreadyReported(ReportedErrorInfo::allowed_in_infallible(guard)));
|
|
}
|
|
} else if new_steps > start && new_steps.is_power_of_two() {
|
|
// Only report after a certain number of terminators have been evaluated and the
|
|
// current number of evaluated terminators is a power of 2. The latter gives us a cheap
|
|
// way to implement exponential backoff.
|
|
let span = ecx.cur_span();
|
|
// We store a unique number in `force_duplicate` to evade `-Z deduplicate-diagnostics`.
|
|
// `new_steps` is guaranteed to be unique because `ecx.machine.num_evaluated_steps` is
|
|
// always increasing.
|
|
ecx.tcx.dcx().emit_warn(LongRunningWarn {
|
|
span,
|
|
item_span: ecx.tcx.span,
|
|
force_duplicate: new_steps,
|
|
});
|
|
}
|
|
}
|
|
|
|
interp_ok(())
|
|
}
|
|
|
|
#[inline(always)]
|
|
fn expose_provenance(
|
|
_ecx: &InterpCx<'tcx, Self>,
|
|
_provenance: Self::Provenance,
|
|
) -> InterpResult<'tcx> {
|
|
// This is only reachable with -Zunleash-the-miri-inside-of-you.
|
|
throw_unsup_format!("exposing pointers is not possible at compile-time")
|
|
}
|
|
|
|
#[inline(always)]
|
|
fn init_frame(
|
|
ecx: &mut InterpCx<'tcx, Self>,
|
|
frame: Frame<'tcx>,
|
|
) -> InterpResult<'tcx, Frame<'tcx>> {
|
|
// Enforce stack size limit. Add 1 because this is run before the new frame is pushed.
|
|
if !ecx.recursion_limit.value_within_limit(ecx.stack().len() + 1) {
|
|
throw_exhaust!(StackFrameLimitReached)
|
|
} else {
|
|
interp_ok(frame)
|
|
}
|
|
}
|
|
|
|
#[inline(always)]
|
|
fn stack<'a>(
|
|
ecx: &'a InterpCx<'tcx, Self>,
|
|
) -> &'a [Frame<'tcx, Self::Provenance, Self::FrameExtra>] {
|
|
&ecx.machine.stack
|
|
}
|
|
|
|
#[inline(always)]
|
|
fn stack_mut<'a>(
|
|
ecx: &'a mut InterpCx<'tcx, Self>,
|
|
) -> &'a mut Vec<Frame<'tcx, Self::Provenance, Self::FrameExtra>> {
|
|
&mut ecx.machine.stack
|
|
}
|
|
|
|
fn before_access_global(
|
|
_tcx: TyCtxtAt<'tcx>,
|
|
machine: &Self,
|
|
alloc_id: AllocId,
|
|
alloc: ConstAllocation<'tcx>,
|
|
_static_def_id: Option<DefId>,
|
|
is_write: bool,
|
|
) -> InterpResult<'tcx> {
|
|
let alloc = alloc.inner();
|
|
if is_write {
|
|
// Write access. These are never allowed, but we give a targeted error message.
|
|
match alloc.mutability {
|
|
Mutability::Not => throw_ub!(WriteToReadOnly(alloc_id)),
|
|
Mutability::Mut => Err(ConstEvalErrKind::ModifiedGlobal).into(),
|
|
}
|
|
} else {
|
|
// Read access. These are usually allowed, with some exceptions.
|
|
if machine.can_access_mut_global == CanAccessMutGlobal::Yes {
|
|
// Machine configuration allows us read from anything (e.g., `static` initializer).
|
|
interp_ok(())
|
|
} else if alloc.mutability == Mutability::Mut {
|
|
// Machine configuration does not allow us to read statics (e.g., `const`
|
|
// initializer).
|
|
Err(ConstEvalErrKind::ConstAccessesMutGlobal).into()
|
|
} else {
|
|
// Immutable global, this read is fine.
|
|
assert_eq!(alloc.mutability, Mutability::Not);
|
|
interp_ok(())
|
|
}
|
|
}
|
|
}
|
|
|
|
fn retag_ptr_value(
|
|
ecx: &mut InterpCx<'tcx, Self>,
|
|
_kind: mir::RetagKind,
|
|
val: &ImmTy<'tcx, CtfeProvenance>,
|
|
) -> InterpResult<'tcx, ImmTy<'tcx, CtfeProvenance>> {
|
|
// If it's a frozen shared reference that's not already immutable, potentially make it immutable.
|
|
// (Do nothing on `None` provenance, that cannot store immutability anyway.)
|
|
if let ty::Ref(_, ty, mutbl) = val.layout.ty.kind()
|
|
&& *mutbl == Mutability::Not
|
|
&& val
|
|
.to_scalar_and_meta()
|
|
.0
|
|
.to_pointer(ecx)?
|
|
.provenance
|
|
.is_some_and(|p| !p.immutable())
|
|
{
|
|
// That next check is expensive, that's why we have all the guards above.
|
|
let is_immutable = ty.is_freeze(*ecx.tcx, ecx.typing_env());
|
|
let place = ecx.ref_to_mplace(val)?;
|
|
let new_place = if is_immutable {
|
|
place.map_provenance(CtfeProvenance::as_immutable)
|
|
} else {
|
|
// Even if it is not immutable, remember that it is a shared reference.
|
|
// This allows it to become part of the final value of the constant.
|
|
// (See <https://github.com/rust-lang/rust/pull/128543> for why we allow this
|
|
// even when there is interior mutability.)
|
|
place.map_provenance(CtfeProvenance::as_shared_ref)
|
|
};
|
|
interp_ok(ImmTy::from_immediate(new_place.to_ref(ecx), val.layout))
|
|
} else {
|
|
interp_ok(val.clone())
|
|
}
|
|
}
|
|
|
|
fn before_memory_write(
|
|
_tcx: TyCtxtAt<'tcx>,
|
|
_machine: &mut Self,
|
|
_alloc_extra: &mut Self::AllocExtra,
|
|
_ptr: Pointer<Option<Self::Provenance>>,
|
|
(_alloc_id, immutable): (AllocId, bool),
|
|
range: AllocRange,
|
|
) -> InterpResult<'tcx> {
|
|
if range.size == Size::ZERO {
|
|
// Nothing to check.
|
|
return interp_ok(());
|
|
}
|
|
// Reject writes through immutable pointers.
|
|
if immutable {
|
|
return Err(ConstEvalErrKind::WriteThroughImmutablePointer).into();
|
|
}
|
|
// Everything else is fine.
|
|
interp_ok(())
|
|
}
|
|
|
|
fn before_alloc_access(
|
|
tcx: TyCtxtAt<'tcx>,
|
|
machine: &Self,
|
|
alloc_id: AllocId,
|
|
) -> InterpResult<'tcx> {
|
|
if machine.stack.is_empty() {
|
|
// Get out of the way for the final copy.
|
|
return interp_ok(());
|
|
}
|
|
// Check if this is the currently evaluated static.
|
|
if Some(alloc_id) == machine.static_root_ids.map(|(id, _)| id) {
|
|
return Err(ConstEvalErrKind::RecursiveStatic).into();
|
|
}
|
|
// If this is another static, make sure we fire off the query to detect cycles.
|
|
// But only do that when checks for static recursion are enabled.
|
|
if machine.static_root_ids.is_some() {
|
|
if let Some(GlobalAlloc::Static(def_id)) = tcx.try_get_global_alloc(alloc_id) {
|
|
if tcx.is_foreign_item(def_id) {
|
|
throw_unsup!(ExternStatic(def_id));
|
|
}
|
|
tcx.eval_static_initializer(def_id)?;
|
|
}
|
|
}
|
|
interp_ok(())
|
|
}
|
|
|
|
fn cached_union_data_range<'e>(
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|
ecx: &'e mut InterpCx<'tcx, Self>,
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|
ty: Ty<'tcx>,
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|
compute_range: impl FnOnce() -> RangeSet,
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|
) -> Cow<'e, RangeSet> {
|
|
if ecx.tcx.sess.opts.unstable_opts.extra_const_ub_checks {
|
|
Cow::Borrowed(ecx.machine.union_data_ranges.entry(ty).or_insert_with(compute_range))
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|
} else {
|
|
// Don't bother caching, we're only doing one validation at the end anyway.
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|
Cow::Owned(compute_range())
|
|
}
|
|
}
|
|
|
|
fn get_default_alloc_params(&self) -> <Self::Bytes as mir::interpret::AllocBytes>::AllocParams {
|
|
}
|
|
}
|
|
|
|
// Please do not add any code below the above `Machine` trait impl. I (oli-obk) plan more cleanups
|
|
// so we can end up having a file with just that impl, but for now, let's keep the impl discoverable
|
|
// at the bottom of this file.
|