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Auto merge of #118324 - RalfJung:ctfe-read-only-pointers, r=saethlin

compile-time evaluation: detect writes through immutable pointers

This has two motivations:
- it unblocks https://github.com/rust-lang/rust/pull/116745 (and therefore takes a big step towards `const_mut_refs` stabilization), because we can now detect if the memory that we find in `const` can be interned as "immutable"
- it would detect the UB that was uncovered in https://github.com/rust-lang/rust/pull/117905, which was caused by accidental stabilization of `copy` functions in `const` that can only be called with UB

When UB is detected, we emit a future-compat warn-by-default lint. This is not a breaking change, so completely in line with [the const-UB RFC](https://rust-lang.github.io/rfcs/3016-const-ub.html), meaning we don't need t-lang FCP here. I made the lint immediately show up for dependencies since it is nearly impossible to even trigger this lint without `const_mut_refs` -- the accidentally stabilized `copy` functions are the only way this can happen, so the crates that popped up in #117905 are the only causes of such UB (in the code that crater covers), and the three cases of UB that we know about have all been fixed in their respective crates already.

The way this is implemented is by making use of the fact that our interpreter is already generic over the notion of provenance. For CTFE we now use the new `CtfeProvenance` type which is conceptually an `AllocId` plus a boolean `immutable` flag (but packed for a more efficient representation). This means we can mark a pointer as immutable when it is created as a shared reference. The flag will be propagated to all pointers derived from this one. We can then check the immutable flag on each write to reject writes through immutable pointers.

I just hope perf works out.
This commit is contained in:
bors 2023-12-07 18:11:01 +00:00
commit 0e7f91b75e
86 changed files with 784 additions and 462 deletions

View file

@ -1,14 +1,16 @@
use std::mem;
use rustc_errors::{DiagnosticArgValue, DiagnosticMessage, IntoDiagnostic, IntoDiagnosticArg};
use rustc_hir::CRATE_HIR_ID;
use rustc_middle::mir::AssertKind;
use rustc_middle::query::TyCtxtAt;
use rustc_middle::ty::TyCtxt;
use rustc_middle::ty::{layout::LayoutError, ConstInt};
use rustc_span::{ErrorGuaranteed, Span, Symbol, DUMMY_SP};
use super::InterpCx;
use super::{CompileTimeInterpreter, InterpCx};
use crate::errors::{self, FrameNote, ReportErrorExt};
use crate::interpret::{ErrorHandled, InterpError, InterpErrorInfo, Machine, MachineStopType};
use crate::interpret::{ErrorHandled, InterpError, InterpErrorInfo, MachineStopType};
/// The CTFE machine has some custom error kinds.
#[derive(Clone, Debug)]
@ -57,16 +59,20 @@ impl<'tcx> Into<InterpErrorInfo<'tcx>> for ConstEvalErrKind {
}
}
pub fn get_span_and_frames<'tcx, 'mir, M: Machine<'mir, 'tcx>>(
ecx: &InterpCx<'mir, 'tcx, M>,
pub fn get_span_and_frames<'tcx, 'mir>(
tcx: TyCtxtAt<'tcx>,
machine: &CompileTimeInterpreter<'mir, 'tcx>,
) -> (Span, Vec<errors::FrameNote>)
where
'tcx: 'mir,
{
let mut stacktrace = ecx.generate_stacktrace();
let mut stacktrace =
InterpCx::<CompileTimeInterpreter<'mir, 'tcx>>::generate_stacktrace_from_stack(
&machine.stack,
);
// Filter out `requires_caller_location` frames.
stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*ecx.tcx));
let span = stacktrace.first().map(|f| f.span).unwrap_or(ecx.tcx.span);
stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(*tcx));
let span = stacktrace.first().map(|f| f.span).unwrap_or(tcx.span);
let mut frames = Vec::new();
@ -87,7 +93,7 @@ where
let mut last_frame: Option<errors::FrameNote> = None;
for frame_info in &stacktrace {
let frame = frame_info.as_note(*ecx.tcx);
let frame = frame_info.as_note(*tcx);
match last_frame.as_mut() {
Some(last_frame)
if last_frame.span == frame.span
@ -156,3 +162,25 @@ where
}
}
}
/// Emit a lint from a const-eval situation.
// Even if this is unused, please don't remove it -- chances are we will need to emit a lint during const-eval again in the future!
pub(super) fn lint<'tcx, 'mir, L>(
tcx: TyCtxtAt<'tcx>,
machine: &CompileTimeInterpreter<'mir, 'tcx>,
lint: &'static rustc_session::lint::Lint,
decorator: impl FnOnce(Vec<errors::FrameNote>) -> L,
) where
L: for<'a> rustc_errors::DecorateLint<'a, ()>,
{
let (span, frames) = get_span_and_frames(tcx, machine);
tcx.emit_spanned_lint(
lint,
// We use the root frame for this so the crate that defines the const defines whether the
// lint is emitted.
machine.stack.first().and_then(|frame| frame.lint_root()).unwrap_or(CRATE_HIR_ID),
span,
decorator(frames),
);
}

View file

@ -155,8 +155,8 @@ pub(super) fn op_to_const<'tcx>(
match immediate {
Left(ref mplace) => {
// We know `offset` is relative to the allocation, so we can use `into_parts`.
let (alloc_id, offset) = mplace.ptr().into_parts();
let alloc_id = alloc_id.expect("cannot have `fake` place fot non-ZST type");
let (prov, offset) = mplace.ptr().into_parts();
let alloc_id = prov.expect("cannot have `fake` place for non-ZST type").alloc_id();
ConstValue::Indirect { alloc_id, offset }
}
// see comment on `let force_as_immediate` above
@ -178,8 +178,8 @@ pub(super) fn op_to_const<'tcx>(
);
let msg = "`op_to_const` on an immediate scalar pair must only be used on slice references to the beginning of an actual allocation";
// We know `offset` is relative to the allocation, so we can use `into_parts`.
let (alloc_id, offset) = a.to_pointer(ecx).expect(msg).into_parts();
let alloc_id = alloc_id.expect(msg);
let (prov, offset) = a.to_pointer(ecx).expect(msg).into_parts();
let alloc_id = prov.expect(msg).alloc_id();
let data = ecx.tcx.global_alloc(alloc_id).unwrap_memory();
assert!(offset == abi::Size::ZERO, "{}", msg);
let meta = b.to_target_usize(ecx).expect(msg);
@ -338,7 +338,7 @@ pub fn eval_in_interpreter<'mir, 'tcx>(
*ecx.tcx,
error,
None,
|| super::get_span_and_frames(&ecx),
|| super::get_span_and_frames(ecx.tcx, &ecx.machine),
|span, frames| ConstEvalError {
span,
error_kind: kind,
@ -353,7 +353,7 @@ pub fn eval_in_interpreter<'mir, 'tcx>(
let validation =
const_validate_mplace(&ecx, &mplace, is_static, cid.promoted.is_some());
let alloc_id = mplace.ptr().provenance.unwrap();
let alloc_id = mplace.ptr().provenance.unwrap().alloc_id();
// Validation failed, report an error.
if let Err(error) = validation {
@ -419,7 +419,7 @@ pub fn const_report_error<'mir, 'tcx>(
*ecx.tcx,
error,
None,
|| crate::const_eval::get_span_and_frames(ecx),
|| crate::const_eval::get_span_and_frames(ecx.tcx, &ecx.machine),
move |span, frames| errors::UndefinedBehavior { span, ub_note, frames, raw_bytes },
)
}

View file

@ -1,30 +1,30 @@
use rustc_hir::def::DefKind;
use rustc_hir::LangItem;
use rustc_middle::mir;
use rustc_middle::mir::interpret::PointerArithmetic;
use rustc_middle::ty::layout::{FnAbiOf, TyAndLayout};
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::Span;
use std::borrow::Borrow;
use std::fmt;
use std::hash::Hash;
use std::ops::ControlFlow;
use rustc_ast::Mutability;
use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::fx::IndexEntry;
use std::fmt;
use rustc_ast::Mutability;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::DefId;
use rustc_hir::LangItem;
use rustc_middle::mir;
use rustc_middle::mir::AssertMessage;
use rustc_middle::query::TyCtxtAt;
use rustc_middle::ty;
use rustc_middle::ty::layout::{FnAbiOf, TyAndLayout};
use rustc_session::lint::builtin::WRITES_THROUGH_IMMUTABLE_POINTER;
use rustc_span::symbol::{sym, Symbol};
use rustc_span::Span;
use rustc_target::abi::{Align, Size};
use rustc_target::spec::abi::Abi as CallAbi;
use crate::errors::{LongRunning, LongRunningWarn};
use crate::fluent_generated as fluent;
use crate::interpret::{
self, compile_time_machine, AllocId, ConstAllocation, FnArg, FnVal, Frame, ImmTy, InterpCx,
InterpResult, OpTy, PlaceTy, Pointer, Scalar,
self, compile_time_machine, AllocId, AllocRange, ConstAllocation, CtfeProvenance, FnArg, FnVal,
Frame, ImmTy, InterpCx, InterpResult, OpTy, PlaceTy, Pointer, PointerArithmetic, Scalar,
};
use super::error::*;
@ -49,7 +49,7 @@ pub struct CompileTimeInterpreter<'mir, 'tcx> {
pub(super) num_evaluated_steps: usize,
/// The virtual call stack.
pub(super) stack: Vec<Frame<'mir, 'tcx, AllocId, ()>>,
pub(super) stack: Vec<Frame<'mir, 'tcx>>,
/// We need to make sure consts never point to anything mutable, even recursively. That is
/// relied on for pattern matching on consts with references.
@ -638,10 +638,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
}
#[inline(always)]
fn expose_ptr(
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
_ptr: Pointer<AllocId>,
) -> InterpResult<'tcx> {
fn expose_ptr(_ecx: &mut InterpCx<'mir, 'tcx, Self>, _ptr: Pointer) -> InterpResult<'tcx> {
// This is only reachable with -Zunleash-the-miri-inside-of-you.
throw_unsup_format!("exposing pointers is not possible at compile-time")
}
@ -674,7 +671,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
}
fn before_access_global(
_tcx: TyCtxt<'tcx>,
_tcx: TyCtxtAt<'tcx>,
machine: &Self,
alloc_id: AllocId,
alloc: ConstAllocation<'tcx>,
@ -711,6 +708,48 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
}
}
}
fn retag_ptr_value(
ecx: &mut InterpCx<'mir, '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, 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.
&& ty.is_freeze(*ecx.tcx, ecx.param_env)
{
let place = ecx.ref_to_mplace(val)?;
let new_place = place.map_provenance(|p| p.map(CtfeProvenance::as_immutable));
Ok(ImmTy::from_immediate(new_place.to_ref(ecx), val.layout))
} else {
Ok(val.clone())
}
}
fn before_memory_write(
tcx: TyCtxtAt<'tcx>,
machine: &mut Self,
_alloc_extra: &mut Self::AllocExtra,
(_alloc_id, immutable): (AllocId, bool),
range: AllocRange,
) -> InterpResult<'tcx> {
if range.size == Size::ZERO {
// Nothing to check.
return Ok(());
}
// Reject writes through immutable pointers.
if immutable {
super::lint(tcx, machine, WRITES_THROUGH_IMMUTABLE_POINTER, |frames| {
crate::errors::WriteThroughImmutablePointer { frames }
});
}
// Everything else is fine.
Ok(())
}
}
// Please do not add any code below the above `Machine` trait impl. I (oli-obk) plan more cleanups

View file

@ -402,6 +402,13 @@ pub struct ConstEvalError {
pub frame_notes: Vec<FrameNote>,
}
#[derive(LintDiagnostic)]
#[diag(const_eval_write_through_immutable_pointer)]
pub struct WriteThroughImmutablePointer {
#[subdiagnostic]
pub frames: Vec<FrameNote>,
}
#[derive(Diagnostic)]
#[diag(const_eval_nullary_intrinsic_fail)]
pub struct NullaryIntrinsicError {

View file

@ -7,7 +7,9 @@ use hir::CRATE_HIR_ID;
use rustc_hir::{self as hir, def_id::DefId, definitions::DefPathData};
use rustc_index::IndexVec;
use rustc_middle::mir;
use rustc_middle::mir::interpret::{ErrorHandled, InvalidMetaKind, ReportedErrorInfo};
use rustc_middle::mir::interpret::{
CtfeProvenance, ErrorHandled, InvalidMetaKind, ReportedErrorInfo,
};
use rustc_middle::query::TyCtxtAt;
use rustc_middle::ty::layout::{
self, FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOf, LayoutOfHelpers,
@ -20,9 +22,9 @@ use rustc_span::Span;
use rustc_target::abi::{call::FnAbi, Align, HasDataLayout, Size, TargetDataLayout};
use super::{
AllocId, GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine, MemPlace,
MemPlaceMeta, Memory, MemoryKind, OpTy, Operand, Place, PlaceTy, Pointer, PointerArithmetic,
Projectable, Provenance, Scalar, StackPopJump,
GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta,
Memory, MemoryKind, OpTy, Operand, Place, PlaceTy, Pointer, PointerArithmetic, Projectable,
Provenance, Scalar, StackPopJump,
};
use crate::errors;
use crate::util;
@ -84,7 +86,7 @@ impl Drop for SpanGuard {
}
/// A stack frame.
pub struct Frame<'mir, 'tcx, Prov: Provenance = AllocId, Extra = ()> {
pub struct Frame<'mir, 'tcx, Prov: Provenance = CtfeProvenance, Extra = ()> {
////////////////////////////////////////////////////////////////////////////////
// Function and callsite information
////////////////////////////////////////////////////////////////////////////////
@ -156,7 +158,7 @@ pub enum StackPopCleanup {
/// State of a local variable including a memoized layout
#[derive(Clone)]
pub struct LocalState<'tcx, Prov: Provenance = AllocId> {
pub struct LocalState<'tcx, Prov: Provenance = CtfeProvenance> {
value: LocalValue<Prov>,
/// Don't modify if `Some`, this is only used to prevent computing the layout twice.
/// Avoids computing the layout of locals that are never actually initialized.
@ -177,7 +179,7 @@ impl<Prov: Provenance> std::fmt::Debug for LocalState<'_, Prov> {
/// This does not store the type of the local; the type is given by `body.local_decls` and can never
/// change, so by not storing here we avoid having to maintain that as an invariant.
#[derive(Copy, Clone, Debug)] // Miri debug-prints these
pub(super) enum LocalValue<Prov: Provenance = AllocId> {
pub(super) enum LocalValue<Prov: Provenance = CtfeProvenance> {
/// This local is not currently alive, and cannot be used at all.
Dead,
/// A normal, live local.

View file

@ -18,7 +18,7 @@ use super::validity::RefTracking;
use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
use rustc_middle::mir::interpret::InterpResult;
use rustc_middle::mir::interpret::{CtfeProvenance, InterpResult};
use rustc_middle::ty::{self, layout::TyAndLayout, Ty};
use rustc_ast::Mutability;
@ -34,7 +34,7 @@ pub trait CompileTimeMachine<'mir, 'tcx: 'mir, T> = Machine<
'mir,
'tcx,
MemoryKind = T,
Provenance = AllocId,
Provenance = CtfeProvenance,
ExtraFnVal = !,
FrameExtra = (),
AllocExtra = (),
@ -135,7 +135,7 @@ fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx, const_eval:
alloc.mutability = Mutability::Not;
};
// link the alloc id to the actual allocation
leftover_allocations.extend(alloc.provenance().ptrs().iter().map(|&(_, alloc_id)| alloc_id));
leftover_allocations.extend(alloc.provenance().ptrs().iter().map(|&(_, prov)| prov.alloc_id()));
let alloc = tcx.mk_const_alloc(alloc);
tcx.set_alloc_id_memory(alloc_id, alloc);
None
@ -178,10 +178,10 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
tcx.struct_tail_erasing_lifetimes(referenced_ty, self.ecx.param_env).kind()
{
let ptr = mplace.meta().unwrap_meta().to_pointer(&tcx)?;
if let Some(alloc_id) = ptr.provenance {
if let Some(prov) = ptr.provenance {
// Explicitly choose const mode here, since vtables are immutable, even
// if the reference of the fat pointer is mutable.
self.intern_shallow(alloc_id, InternMode::Const, None);
self.intern_shallow(prov.alloc_id(), InternMode::Const, None);
} else {
// Validation will error (with a better message) on an invalid vtable pointer.
// Let validation show the error message, but make sure it *does* error.
@ -191,7 +191,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
}
// Check if we have encountered this pointer+layout combination before.
// Only recurse for allocation-backed pointers.
if let Some(alloc_id) = mplace.ptr().provenance {
if let Some(prov) = mplace.ptr().provenance {
// Compute the mode with which we intern this. Our goal here is to make as many
// statics as we can immutable so they can be placed in read-only memory by LLVM.
let ref_mode = match self.mode {
@ -234,7 +234,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
InternMode::Const
}
};
match self.intern_shallow(alloc_id, ref_mode, Some(referenced_ty)) {
match self.intern_shallow(prov.alloc_id(), ref_mode, Some(referenced_ty)) {
// No need to recurse, these are interned already and statics may have
// cycles, so we don't want to recurse there
Some(IsStaticOrFn) => {}
@ -353,7 +353,7 @@ pub fn intern_const_alloc_recursive<
leftover_allocations,
// The outermost allocation must exist, because we allocated it with
// `Memory::allocate`.
ret.ptr().provenance.unwrap(),
ret.ptr().provenance.unwrap().alloc_id(),
base_intern_mode,
Some(ret.layout.ty),
);
@ -431,7 +431,8 @@ pub fn intern_const_alloc_recursive<
}
let alloc = tcx.mk_const_alloc(alloc);
tcx.set_alloc_id_memory(alloc_id, alloc);
for &(_, alloc_id) in alloc.inner().provenance().ptrs().iter() {
for &(_, prov) in alloc.inner().provenance().ptrs().iter() {
let alloc_id = prov.alloc_id();
if leftover_allocations.insert(alloc_id) {
todo.push(alloc_id);
}
@ -503,10 +504,11 @@ impl<'mir, 'tcx: 'mir, M: super::intern::CompileTimeMachine<'mir, 'tcx, !>>
// `allocate` picks a fresh AllocId that we will associate with its data below.
let dest = self.allocate(layout, MemoryKind::Stack)?;
f(self, &dest.clone().into())?;
let mut alloc = self.memory.alloc_map.remove(&dest.ptr().provenance.unwrap()).unwrap().1;
let mut alloc =
self.memory.alloc_map.remove(&dest.ptr().provenance.unwrap().alloc_id()).unwrap().1;
alloc.mutability = Mutability::Not;
let alloc = self.tcx.mk_const_alloc(alloc);
let alloc_id = dest.ptr().provenance.unwrap(); // this was just allocated, it must have provenance
let alloc_id = dest.ptr().provenance.unwrap().alloc_id(); // this was just allocated, it must have provenance
self.tcx.set_alloc_id_memory(alloc_id, alloc);
Ok(alloc_id)
}

View file

@ -9,15 +9,17 @@ use std::hash::Hash;
use rustc_apfloat::{Float, FloatConvert};
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_middle::mir;
use rustc_middle::query::TyCtxtAt;
use rustc_middle::ty;
use rustc_middle::ty::layout::TyAndLayout;
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::def_id::DefId;
use rustc_target::abi::{Align, Size};
use rustc_target::spec::abi::Abi as CallAbi;
use super::{
AllocBytes, AllocId, AllocKind, AllocRange, Allocation, ConstAllocation, FnArg, Frame, ImmTy,
InterpCx, InterpResult, MPlaceTy, MemoryKind, Misalignment, OpTy, PlaceTy, Pointer, Provenance,
AllocBytes, AllocId, AllocKind, AllocRange, Allocation, ConstAllocation, CtfeProvenance, FnArg,
Frame, ImmTy, InterpCx, InterpResult, MPlaceTy, MemoryKind, Misalignment, OpTy, PlaceTy,
Pointer, Provenance,
};
/// Data returned by Machine::stack_pop,
@ -292,7 +294,7 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
/// `def_id` is `Some` if this is the "lazy" allocation of a static.
#[inline]
fn before_access_global(
_tcx: TyCtxt<'tcx>,
_tcx: TyCtxtAt<'tcx>,
_machine: &Self,
_alloc_id: AllocId,
_allocation: ConstAllocation<'tcx>,
@ -387,7 +389,7 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
/// need to mutate.
#[inline(always)]
fn before_memory_read(
_tcx: TyCtxt<'tcx>,
_tcx: TyCtxtAt<'tcx>,
_machine: &Self,
_alloc_extra: &Self::AllocExtra,
_prov: (AllocId, Self::ProvenanceExtra),
@ -399,7 +401,7 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
/// Hook for performing extra checks on a memory write access.
#[inline(always)]
fn before_memory_write(
_tcx: TyCtxt<'tcx>,
_tcx: TyCtxtAt<'tcx>,
_machine: &mut Self,
_alloc_extra: &mut Self::AllocExtra,
_prov: (AllocId, Self::ProvenanceExtra),
@ -411,7 +413,7 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
/// Hook for performing extra operations on a memory deallocation.
#[inline(always)]
fn before_memory_deallocation(
_tcx: TyCtxt<'tcx>,
_tcx: TyCtxtAt<'tcx>,
_machine: &mut Self,
_alloc_extra: &mut Self::AllocExtra,
_prov: (AllocId, Self::ProvenanceExtra),
@ -513,8 +515,8 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
/// A lot of the flexibility above is just needed for `Miri`, but all "compile-time" machines
/// (CTFE and ConstProp) use the same instance. Here, we share that code.
pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
type Provenance = AllocId;
type ProvenanceExtra = ();
type Provenance = CtfeProvenance;
type ProvenanceExtra = bool; // the "immutable" flag
type ExtraFnVal = !;
@ -567,14 +569,14 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
def_id: DefId,
) -> InterpResult<$tcx, Pointer> {
// Use the `AllocId` associated with the `DefId`. Any actual *access* will fail.
Ok(Pointer::new(ecx.tcx.reserve_and_set_static_alloc(def_id), Size::ZERO))
Ok(Pointer::new(ecx.tcx.reserve_and_set_static_alloc(def_id).into(), Size::ZERO))
}
#[inline(always)]
fn adjust_alloc_base_pointer(
_ecx: &InterpCx<$mir, $tcx, Self>,
ptr: Pointer<AllocId>,
) -> InterpResult<$tcx, Pointer<AllocId>> {
ptr: Pointer<CtfeProvenance>,
) -> InterpResult<$tcx, Pointer<CtfeProvenance>> {
Ok(ptr)
}
@ -582,7 +584,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
fn ptr_from_addr_cast(
_ecx: &InterpCx<$mir, $tcx, Self>,
addr: u64,
) -> InterpResult<$tcx, Pointer<Option<AllocId>>> {
) -> InterpResult<$tcx, Pointer<Option<CtfeProvenance>>> {
// Allow these casts, but make the pointer not dereferenceable.
// (I.e., they behave like transmutation.)
// This is correct because no pointers can ever be exposed in compile-time evaluation.
@ -592,10 +594,10 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
#[inline(always)]
fn ptr_get_alloc(
_ecx: &InterpCx<$mir, $tcx, Self>,
ptr: Pointer<AllocId>,
ptr: Pointer<CtfeProvenance>,
) -> Option<(AllocId, Size, Self::ProvenanceExtra)> {
// We know `offset` is relative to the allocation, so we can use `into_parts`.
let (alloc_id, offset) = ptr.into_parts();
Some((alloc_id, offset, ()))
let (prov, offset) = ptr.into_parts();
Some((prov.alloc_id(), offset, prov.immutable()))
}
}

View file

@ -22,8 +22,8 @@ use crate::fluent_generated as fluent;
use super::{
alloc_range, AllocBytes, AllocId, AllocMap, AllocRange, Allocation, CheckAlignMsg,
CheckInAllocMsg, GlobalAlloc, InterpCx, InterpResult, Machine, MayLeak, Misalignment, Pointer,
PointerArithmetic, Provenance, Scalar,
CheckInAllocMsg, CtfeProvenance, GlobalAlloc, InterpCx, InterpResult, Machine, MayLeak,
Misalignment, Pointer, PointerArithmetic, Provenance, Scalar,
};
#[derive(Debug, PartialEq, Copy, Clone)]
@ -159,9 +159,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
#[inline]
pub fn global_base_pointer(
&self,
ptr: Pointer<AllocId>,
ptr: Pointer<CtfeProvenance>,
) -> InterpResult<'tcx, Pointer<M::Provenance>> {
let alloc_id = ptr.provenance;
let alloc_id = ptr.provenance.alloc_id();
// We need to handle `extern static`.
match self.tcx.try_get_global_alloc(alloc_id) {
Some(GlobalAlloc::Static(def_id)) if self.tcx.is_thread_local_static(def_id) => {
@ -339,7 +339,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// Let the machine take some extra action
let size = alloc.size();
M::before_memory_deallocation(
*self.tcx,
self.tcx,
&mut self.machine,
&mut alloc.extra,
(alloc_id, prov),
@ -561,7 +561,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
(val, Some(def_id))
}
};
M::before_access_global(*self.tcx, &self.machine, id, alloc, def_id, is_write)?;
M::before_access_global(self.tcx, &self.machine, id, alloc, def_id, is_write)?;
// We got tcx memory. Let the machine initialize its "extra" stuff.
M::adjust_allocation(
self,
@ -626,7 +626,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
)?;
if let Some((alloc_id, offset, prov, alloc)) = ptr_and_alloc {
let range = alloc_range(offset, size);
M::before_memory_read(*self.tcx, &self.machine, &alloc.extra, (alloc_id, prov), range)?;
M::before_memory_read(self.tcx, &self.machine, &alloc.extra, (alloc_id, prov), range)?;
Ok(Some(AllocRef { alloc, range, tcx: *self.tcx, alloc_id }))
} else {
// Even in this branch we have to be sure that we actually access the allocation, in
@ -687,13 +687,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
{
let parts = self.get_ptr_access(ptr, size)?;
if let Some((alloc_id, offset, prov)) = parts {
let tcx = *self.tcx;
let tcx = self.tcx;
// FIXME: can we somehow avoid looking up the allocation twice here?
// We cannot call `get_raw_mut` inside `check_and_deref_ptr` as that would duplicate `&mut self`.
let (alloc, machine) = self.get_alloc_raw_mut(alloc_id)?;
let range = alloc_range(offset, size);
M::before_memory_write(tcx, machine, &mut alloc.extra, (alloc_id, prov), range)?;
Ok(Some(AllocRefMut { alloc, range, tcx, alloc_id }))
Ok(Some(AllocRefMut { alloc, range, tcx: *tcx, alloc_id }))
} else {
Ok(None)
}
@ -1133,7 +1133,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let src_alloc = self.get_alloc_raw(src_alloc_id)?;
let src_range = alloc_range(src_offset, size);
M::before_memory_read(
*tcx,
tcx,
&self.machine,
&src_alloc.extra,
(src_alloc_id, src_prov),
@ -1163,7 +1163,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let (dest_alloc, extra) = self.get_alloc_raw_mut(dest_alloc_id)?;
let dest_range = alloc_range(dest_offset, size * num_copies);
M::before_memory_write(
*tcx,
tcx,
extra,
&mut dest_alloc.extra,
(dest_alloc_id, dest_prov),

View file

@ -13,9 +13,9 @@ use rustc_middle::{mir, ty};
use rustc_target::abi::{self, Abi, HasDataLayout, Size};
use super::{
alloc_range, from_known_layout, mir_assign_valid_types, AllocId, Frame, InterpCx, InterpResult,
MPlaceTy, Machine, MemPlace, MemPlaceMeta, OffsetMode, PlaceTy, Pointer, Projectable,
Provenance, Scalar,
alloc_range, from_known_layout, mir_assign_valid_types, CtfeProvenance, Frame, InterpCx,
InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta, OffsetMode, PlaceTy, Pointer,
Projectable, Provenance, Scalar,
};
/// An `Immediate` represents a single immediate self-contained Rust value.
@ -26,7 +26,7 @@ use super::{
/// In particular, thanks to `ScalarPair`, arithmetic operations and casts can be entirely
/// defined on `Immediate`, and do not have to work with a `Place`.
#[derive(Copy, Clone, Debug)]
pub enum Immediate<Prov: Provenance = AllocId> {
pub enum Immediate<Prov: Provenance = CtfeProvenance> {
/// A single scalar value (must have *initialized* `Scalar` ABI).
Scalar(Scalar<Prov>),
/// A pair of two scalar value (must have `ScalarPair` ABI where both fields are
@ -93,12 +93,23 @@ impl<Prov: Provenance> Immediate<Prov> {
Immediate::Uninit => bug!("Got uninit where a scalar pair was expected"),
}
}
/// Returns the scalar from the first component and optionally the 2nd component as metadata.
#[inline]
#[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
pub fn to_scalar_and_meta(self) -> (Scalar<Prov>, MemPlaceMeta<Prov>) {
match self {
Immediate::ScalarPair(val1, val2) => (val1, MemPlaceMeta::Meta(val2)),
Immediate::Scalar(val) => (val, MemPlaceMeta::None),
Immediate::Uninit => bug!("Got uninit where a scalar or scalar pair was expected"),
}
}
}
// ScalarPair needs a type to interpret, so we often have an immediate and a type together
// as input for binary and cast operations.
#[derive(Clone)]
pub struct ImmTy<'tcx, Prov: Provenance = AllocId> {
pub struct ImmTy<'tcx, Prov: Provenance = CtfeProvenance> {
imm: Immediate<Prov>,
pub layout: TyAndLayout<'tcx>,
}
@ -334,13 +345,13 @@ impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for ImmTy<'tcx, Prov> {
/// or still in memory. The latter is an optimization, to delay reading that chunk of
/// memory and to avoid having to store arbitrary-sized data here.
#[derive(Copy, Clone, Debug)]
pub(super) enum Operand<Prov: Provenance = AllocId> {
pub(super) enum Operand<Prov: Provenance = CtfeProvenance> {
Immediate(Immediate<Prov>),
Indirect(MemPlace<Prov>),
}
#[derive(Clone)]
pub struct OpTy<'tcx, Prov: Provenance = AllocId> {
pub struct OpTy<'tcx, Prov: Provenance = CtfeProvenance> {
op: Operand<Prov>, // Keep this private; it helps enforce invariants.
pub layout: TyAndLayout<'tcx>,
}
@ -750,17 +761,19 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let layout = from_known_layout(self.tcx, self.param_env, layout, || self.layout_of(ty))?;
let imm = match val_val {
mir::ConstValue::Indirect { alloc_id, offset } => {
// We rely on mutability being set correctly in that allocation to prevent writes
// where none should happen.
let ptr = self.global_base_pointer(Pointer::new(alloc_id, offset))?;
// This is const data, no mutation allowed.
let ptr = self.global_base_pointer(Pointer::new(
CtfeProvenance::from(alloc_id).as_immutable(),
offset,
))?;
return Ok(self.ptr_to_mplace(ptr.into(), layout).into());
}
mir::ConstValue::Scalar(x) => adjust_scalar(x)?.into(),
mir::ConstValue::ZeroSized => Immediate::Uninit,
mir::ConstValue::Slice { data, meta } => {
// We rely on mutability being set correctly in `data` to prevent writes
// where none should happen.
let ptr = Pointer::new(self.tcx.reserve_and_set_memory_alloc(data), Size::ZERO);
// This is const data, no mutation allowed.
let alloc_id = self.tcx.reserve_and_set_memory_alloc(data);
let ptr = Pointer::new(CtfeProvenance::from(alloc_id).as_immutable(), Size::ZERO);
Immediate::new_slice(self.global_base_pointer(ptr)?.into(), meta, self)
}
};

View file

@ -14,14 +14,14 @@ use rustc_middle::ty::Ty;
use rustc_target::abi::{Abi, Align, HasDataLayout, Size};
use super::{
alloc_range, mir_assign_valid_types, AllocId, AllocRef, AllocRefMut, CheckAlignMsg, ImmTy,
Immediate, InterpCx, InterpResult, Machine, MemoryKind, Misalignment, OffsetMode, OpTy,
alloc_range, mir_assign_valid_types, AllocRef, AllocRefMut, CheckAlignMsg, CtfeProvenance,
ImmTy, Immediate, InterpCx, InterpResult, Machine, MemoryKind, Misalignment, OffsetMode, OpTy,
Operand, Pointer, PointerArithmetic, Projectable, Provenance, Readable, Scalar,
};
#[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)]
/// Information required for the sound usage of a `MemPlace`.
pub enum MemPlaceMeta<Prov: Provenance = AllocId> {
pub enum MemPlaceMeta<Prov: Provenance = CtfeProvenance> {
/// The unsized payload (e.g. length for slices or vtable pointer for trait objects).
Meta(Scalar<Prov>),
/// `Sized` types or unsized `extern type`
@ -49,7 +49,7 @@ impl<Prov: Provenance> MemPlaceMeta<Prov> {
}
#[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)]
pub(super) struct MemPlace<Prov: Provenance = AllocId> {
pub(super) struct MemPlace<Prov: Provenance = CtfeProvenance> {
/// The pointer can be a pure integer, with the `None` provenance.
pub ptr: Pointer<Option<Prov>>,
/// Metadata for unsized places. Interpretation is up to the type.
@ -100,7 +100,7 @@ impl<Prov: Provenance> MemPlace<Prov> {
/// A MemPlace with its layout. Constructing it is only possible in this module.
#[derive(Clone, Hash, Eq, PartialEq)]
pub struct MPlaceTy<'tcx, Prov: Provenance = AllocId> {
pub struct MPlaceTy<'tcx, Prov: Provenance = CtfeProvenance> {
mplace: MemPlace<Prov>,
pub layout: TyAndLayout<'tcx>,
}
@ -179,7 +179,7 @@ impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for MPlaceTy<'tcx, Prov> {
}
#[derive(Copy, Clone, Debug)]
pub(super) enum Place<Prov: Provenance = AllocId> {
pub(super) enum Place<Prov: Provenance = CtfeProvenance> {
/// A place referring to a value allocated in the `Memory` system.
Ptr(MemPlace<Prov>),
@ -195,7 +195,7 @@ pub(super) enum Place<Prov: Provenance = AllocId> {
}
#[derive(Clone)]
pub struct PlaceTy<'tcx, Prov: Provenance = AllocId> {
pub struct PlaceTy<'tcx, Prov: Provenance = CtfeProvenance> {
place: Place<Prov>, // Keep this private; it helps enforce invariants.
pub layout: TyAndLayout<'tcx>,
}
@ -406,11 +406,7 @@ where
let pointee_type =
val.layout.ty.builtin_deref(true).expect("`ref_to_mplace` called on non-ptr type").ty;
let layout = self.layout_of(pointee_type)?;
let (ptr, meta) = match **val {
Immediate::Scalar(ptr) => (ptr, MemPlaceMeta::None),
Immediate::ScalarPair(ptr, meta) => (ptr, MemPlaceMeta::Meta(meta)),
Immediate::Uninit => throw_ub!(InvalidUninitBytes(None)),
};
let (ptr, meta) = val.to_scalar_and_meta();
// `ref_to_mplace` is called on raw pointers even if they don't actually get dereferenced;
// we hence can't call `size_and_align_of` since that asserts more validity than we want.

View file

@ -18,14 +18,14 @@ use rustc_target::abi::{
use rustc_target::spec::abi::Abi;
use super::{
AllocId, FnVal, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, PlaceTy, Projectable,
Provenance, Scalar, StackPopCleanup,
CtfeProvenance, FnVal, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, PlaceTy,
Projectable, Provenance, Scalar, StackPopCleanup,
};
use crate::fluent_generated as fluent;
/// An argment passed to a function.
#[derive(Clone, Debug)]
pub enum FnArg<'tcx, Prov: Provenance = AllocId> {
pub enum FnArg<'tcx, Prov: Provenance = CtfeProvenance> {
/// Pass a copy of the given operand.
Copy(OpTy<'tcx, Prov>),
/// Allow for the argument to be passed in-place: destroy the value originally stored at that place and