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const-eval interner: from-scratch rewrite using mutability informatio…
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…n from provenance rather than types
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RalfJung committed Dec 17, 2023
1 parent 3ad8e2d commit 6854fa3
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Showing 50 changed files with 998 additions and 638 deletions.
22 changes: 14 additions & 8 deletions compiler/rustc_const_eval/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -46,8 +46,8 @@ const_eval_dangling_int_pointer =
{$bad_pointer_message}: {$pointer} is a dangling pointer (it has no provenance)
const_eval_dangling_null_pointer =
{$bad_pointer_message}: null pointer is a dangling pointer (it has no provenance)
const_eval_dangling_ptr_in_final = encountered dangling pointer in final constant
const_eval_dangling_ptr_in_final = encountered dangling pointer in final value of {const_eval_intern_kind}
const_eval_dead_local =
accessing a dead local variable
const_eval_dealloc_immutable =
Expand Down Expand Up @@ -134,6 +134,14 @@ const_eval_interior_mutable_data_refer =
This would make multiple uses of a constant to be able to see different values and allow circumventing
the `Send` and `Sync` requirements for shared mutable data, which is unsound.
const_eval_intern_kind = {$kind ->
[static] static
[static_mut] mutable static
[const] constant
[promoted] promoted
*[other] {""}
}
const_eval_invalid_align =
align has to be a power of 2
Expand Down Expand Up @@ -205,6 +213,8 @@ const_eval_modified_global =
const_eval_mut_deref =
mutation through a reference is not allowed in {const_eval_const_context}s
const_eval_mutable_ptr_in_final = encountered mutable pointer in final value of {const_eval_intern_kind}
const_eval_non_const_fmt_macro_call =
cannot call non-const formatting macro in {const_eval_const_context}s
Expand Down Expand Up @@ -392,9 +402,6 @@ const_eval_unstable_in_stable =
.unstable_sugg = if it is not part of the public API, make this function unstably const
.bypass_sugg = otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks
const_eval_unsupported_untyped_pointer = unsupported untyped pointer in constant
.note = memory only reachable via raw pointers is not supported
const_eval_unterminated_c_string =
reading a null-terminated string starting at {$pointer} with no null found before end of allocation
Expand All @@ -406,7 +413,6 @@ const_eval_upcast_mismatch =
## The `front_matter`s here refer to either `const_eval_front_matter_invalid_value` or `const_eval_front_matter_invalid_value_with_path`.
## (We'd love to sort this differently to make that more clear but tidy won't let us...)
const_eval_validation_box_to_mut = {$front_matter}: encountered a box pointing to mutable memory in a constant
const_eval_validation_box_to_static = {$front_matter}: encountered a box pointing to a static variable in a constant
const_eval_validation_box_to_uninhabited = {$front_matter}: encountered a box pointing to uninhabited type {$ty}
const_eval_validation_dangling_box_no_provenance = {$front_matter}: encountered a dangling box ({$pointer} has no provenance)
Expand Down Expand Up @@ -441,7 +447,8 @@ const_eval_validation_invalid_fn_ptr = {$front_matter}: encountered {$value}, bu
const_eval_validation_invalid_ref_meta = {$front_matter}: encountered invalid reference metadata: total size is bigger than largest supported object
const_eval_validation_invalid_ref_slice_meta = {$front_matter}: encountered invalid reference metadata: slice is bigger than largest supported object
const_eval_validation_invalid_vtable_ptr = {$front_matter}: encountered {$value}, but expected a vtable pointer
const_eval_validation_mutable_ref_in_const = {$front_matter}: encountered mutable reference in a `const`
const_eval_validation_mutable_ref_in_const = {$front_matter}: encountered mutable reference in a `const` or `static`
const_eval_validation_mutable_ref_to_immutable = {$front_matter}: encountered mutable reference or box pointing to read-only memory
const_eval_validation_never_val = {$front_matter}: encountered a value of the never type `!`
const_eval_validation_null_box = {$front_matter}: encountered a null box
const_eval_validation_null_fn_ptr = {$front_matter}: encountered a null function pointer
Expand All @@ -451,15 +458,14 @@ const_eval_validation_out_of_range = {$front_matter}: encountered {$value}, but
const_eval_validation_partial_pointer = {$front_matter}: encountered a partial pointer or a mix of pointers
const_eval_validation_pointer_as_int = {$front_matter}: encountered a pointer, but {$expected}
const_eval_validation_ptr_out_of_range = {$front_matter}: encountered a pointer, but expected something that cannot possibly fail to be {$in_range}
const_eval_validation_ref_to_mut = {$front_matter}: encountered a reference pointing to mutable memory in a constant
const_eval_validation_ref_to_static = {$front_matter}: encountered a reference pointing to a static variable in a constant
const_eval_validation_ref_to_uninhabited = {$front_matter}: encountered a reference pointing to uninhabited type {$ty}
const_eval_validation_unaligned_box = {$front_matter}: encountered an unaligned box (required {$required_bytes} byte alignment but found {$found_bytes})
const_eval_validation_unaligned_ref = {$front_matter}: encountered an unaligned reference (required {$required_bytes} byte alignment but found {$found_bytes})
const_eval_validation_uninhabited_enum_variant = {$front_matter}: encountered an uninhabited enum variant
const_eval_validation_uninhabited_val = {$front_matter}: encountered a value of uninhabited type `{$ty}`
const_eval_validation_uninit = {$front_matter}: encountered uninitialized memory, but {$expected}
const_eval_validation_unsafe_cell = {$front_matter}: encountered `UnsafeCell` in a `const`
const_eval_validation_unsafe_cell = {$front_matter}: encountered `UnsafeCell` in read-only memory
const_eval_write_through_immutable_pointer =
writing through a pointer that was derived from a shared (immutable) reference
Expand Down
32 changes: 19 additions & 13 deletions compiler/rustc_const_eval/src/const_eval/eval_queries.rs
Original file line number Diff line number Diff line change
Expand Up @@ -313,6 +313,9 @@ pub fn eval_in_interpreter<'mir, 'tcx>(
cid: GlobalId<'tcx>,
is_static: bool,
) -> ::rustc_middle::mir::interpret::EvalToAllocationRawResult<'tcx> {
// `is_static` just means "in static", it could still be a promoted!
debug_assert_eq!(is_static, ecx.tcx.static_mutability(cid.instance.def_id()).is_some());

let res = ecx.load_mir(cid.instance.def, cid.promoted);
match res.and_then(|body| eval_body_using_ecx(&mut ecx, cid, body)) {
Err(error) => {
Expand Down Expand Up @@ -350,8 +353,7 @@ pub fn eval_in_interpreter<'mir, 'tcx>(
Ok(mplace) => {
// Since evaluation had no errors, validate the resulting constant.
// This is a separate `try` block to provide more targeted error reporting.
let validation =
const_validate_mplace(&ecx, &mplace, is_static, cid.promoted.is_some());
let validation = const_validate_mplace(&ecx, &mplace, cid);

let alloc_id = mplace.ptr().provenance.unwrap().alloc_id();

Expand All @@ -370,22 +372,26 @@ pub fn eval_in_interpreter<'mir, 'tcx>(
pub fn const_validate_mplace<'mir, 'tcx>(
ecx: &InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>>,
mplace: &MPlaceTy<'tcx>,
is_static: bool,
is_promoted: bool,
cid: GlobalId<'tcx>,
) -> InterpResult<'tcx> {
let mut ref_tracking = RefTracking::new(mplace.clone());
let mut inner = false;
while let Some((mplace, path)) = ref_tracking.todo.pop() {
let mode = if is_static {
if is_promoted {
// Promoteds in statics are allowed to point to statics.
CtfeValidationMode::Const { inner, allow_static_ptrs: true }
} else {
// a `static`
CtfeValidationMode::Regular
let mode = match ecx.tcx.static_mutability(cid.instance.def_id()) {
Some(_) if cid.promoted.is_some() => {
// Promoteds in statics are consts that re allowed to point to statics.
CtfeValidationMode::Const {
allow_immutable_unsafe_cell: false,
allow_static_ptrs: true,
}
}
Some(mutbl) => CtfeValidationMode::Static { mutbl }, // a `static`
None => {
// In normal `const` (not promoted), the outermost allocation is always only copied,
// so having `UnsafeCell` in there is okay despite them being in immutable memory.
let allow_immutable_unsafe_cell = cid.promoted.is_none() && !inner;
CtfeValidationMode::Const { allow_immutable_unsafe_cell, allow_static_ptrs: false }
}
} else {
CtfeValidationMode::Const { inner, allow_static_ptrs: false }
};
ecx.const_validate_operand(&mplace.into(), path, &mut ref_tracking, mode)?;
inner = true;
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_const_eval/src/const_eval/machine.rs
Original file line number Diff line number Diff line change
Expand Up @@ -723,7 +723,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
&& 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));
let new_place = place.map_provenance(CtfeProvenance::as_immutable);
Ok(ImmTy::from_immediate(new_place.to_ref(ecx), val.layout))
} else {
Ok(val.clone())
Expand Down
43 changes: 29 additions & 14 deletions compiler/rustc_const_eval/src/errors.rs
Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
use std::borrow::Cow;

use rustc_errors::{
DiagnosticArgValue, DiagnosticBuilder, DiagnosticMessage, EmissionGuarantee, Handler,
IntoDiagnostic,
Expand All @@ -13,12 +15,24 @@ use rustc_middle::ty::{self, Ty};
use rustc_span::Span;
use rustc_target::abi::call::AdjustForForeignAbiError;
use rustc_target::abi::{Size, WrappingRange};
use rustc_type_ir::Mutability;

use crate::interpret::InternKind;

#[derive(Diagnostic)]
#[diag(const_eval_dangling_ptr_in_final)]
pub(crate) struct DanglingPtrInFinal {
#[primary_span]
pub span: Span,
pub kind: InternKind,
}

#[derive(Diagnostic)]
#[diag(const_eval_mutable_ptr_in_final)]
pub(crate) struct MutablePtrInFinal {
#[primary_span]
pub span: Span,
pub kind: InternKind,
}

#[derive(Diagnostic)]
Expand Down Expand Up @@ -194,14 +208,6 @@ pub(crate) struct UnallowedInlineAsm {
pub kind: ConstContext,
}

#[derive(Diagnostic)]
#[diag(const_eval_unsupported_untyped_pointer)]
#[note]
pub(crate) struct UnsupportedUntypedPointer {
#[primary_span]
pub span: Span,
}

#[derive(Diagnostic)]
#[diag(const_eval_interior_mutable_data_refer, code = "E0492")]
pub(crate) struct InteriorMutableDataRefer {
Expand Down Expand Up @@ -619,18 +625,16 @@ impl<'tcx> ReportErrorExt for ValidationErrorInfo<'tcx> {
PtrToStatic { ptr_kind: PointerKind::Box } => const_eval_validation_box_to_static,
PtrToStatic { ptr_kind: PointerKind::Ref } => const_eval_validation_ref_to_static,

PtrToMut { ptr_kind: PointerKind::Box } => const_eval_validation_box_to_mut,
PtrToMut { ptr_kind: PointerKind::Ref } => const_eval_validation_ref_to_mut,

PointerAsInt { .. } => const_eval_validation_pointer_as_int,
PartialPointer => const_eval_validation_partial_pointer,
MutableRefInConst => const_eval_validation_mutable_ref_in_const,
MutableRefToImmutable => const_eval_validation_mutable_ref_to_immutable,
NullFnPtr => const_eval_validation_null_fn_ptr,
NeverVal => const_eval_validation_never_val,
NullablePtrOutOfRange { .. } => const_eval_validation_nullable_ptr_out_of_range,
PtrOutOfRange { .. } => const_eval_validation_ptr_out_of_range,
OutOfRange { .. } => const_eval_validation_out_of_range,
UnsafeCell => const_eval_validation_unsafe_cell,
UnsafeCellInImmutable => const_eval_validation_unsafe_cell,
UninhabitedVal { .. } => const_eval_validation_uninhabited_val,
InvalidEnumTag { .. } => const_eval_validation_invalid_enum_tag,
UninhabitedEnumVariant => const_eval_validation_uninhabited_enum_variant,
Expand Down Expand Up @@ -776,11 +780,11 @@ impl<'tcx> ReportErrorExt for ValidationErrorInfo<'tcx> {
}
NullPtr { .. }
| PtrToStatic { .. }
| PtrToMut { .. }
| MutableRefInConst
| MutableRefToImmutable
| NullFnPtr
| NeverVal
| UnsafeCell
| UnsafeCellInImmutable
| InvalidMetaSliceTooLarge { .. }
| InvalidMetaTooLarge { .. }
| DanglingPtrUseAfterFree { .. }
Expand Down Expand Up @@ -906,3 +910,14 @@ impl ReportErrorExt for ResourceExhaustionInfo {
}
fn add_args<G: EmissionGuarantee>(self, _: &Handler, _: &mut DiagnosticBuilder<'_, G>) {}
}

impl rustc_errors::IntoDiagnosticArg for InternKind {
fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
DiagnosticArgValue::Str(Cow::Borrowed(match self {
InternKind::Static(Mutability::Not) => "static",
InternKind::Static(Mutability::Mut) => "static_mut",
InternKind::Constant => "const",
InternKind::Promoted => "promoted",
}))
}
}
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