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miri: support 'promising' alignment for symbolic alignment check

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This commit is contained in:
Ralf Jung 2023-11-12 16:06:50 +01:00
parent 7ceaf19868
commit bebba4f6e0
14 changed files with 298 additions and 118 deletions
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29
compiler/rustc_const_eval/src/interpret/machine.rs
View file

@ -12,12 +12,12 @@ use rustc_middle::mir;
use rustc_middle::ty::layout::TyAndLayout;
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::def_id::DefId;
use rustc_target::abi::Size;
use rustc_target::abi::{Align, Size};
use rustc_target::spec::abi::Abi as CallAbi;
use super::{
AllocBytes, AllocId, AllocRange, Allocation, ConstAllocation, FnArg, Frame, ImmTy, InterpCx,
InterpResult, MPlaceTy, MemoryKind, OpTy, PlaceTy, Pointer, Provenance,
AllocBytes, AllocId, AllocKind, AllocRange, Allocation, ConstAllocation, FnArg, Frame, ImmTy,
InterpCx, InterpResult, MPlaceTy, MemoryKind, Misalignment, OpTy, PlaceTy, Pointer, Provenance,
};
/// Data returned by Machine::stack_pop,
@ -143,11 +143,18 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
/// Whether memory accesses should be alignment-checked.
fn enforce_alignment(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool;
/// Whether, when checking alignment, we should look at the actual address and thus support
/// custom alignment logic based on whatever the integer address happens to be.
///
/// If this returns true, Provenance::OFFSET_IS_ADDR must be true.
fn use_addr_for_alignment_check(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool;
/// Gives the machine a chance to detect more misalignment than the built-in checks would catch.
#[inline(always)]
fn alignment_check(
_ecx: &InterpCx<'mir, 'tcx, Self>,
_alloc_id: AllocId,
_alloc_align: Align,
_alloc_kind: AllocKind,
_offset: Size,
_align: Align,
) -> Option<Misalignment> {
None
}
/// Whether to enforce the validity invariant for a specific layout.
fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>, layout: TyAndLayout<'tcx>) -> bool;
@ -519,12 +526,6 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
type FrameExtra = ();
type Bytes = Box<[u8]>;
#[inline(always)]
fn use_addr_for_alignment_check(_ecx: &InterpCx<$mir, $tcx, Self>) -> bool {
// We do not support `use_addr`.
false
}
#[inline(always)]
fn ignore_optional_overflow_checks(_ecx: &InterpCx<$mir, $tcx, Self>) -> bool {
false

9
compiler/rustc_const_eval/src/interpret/memory.rs
View file

@ -58,6 +58,7 @@ impl<T: fmt::Display> fmt::Display for MemoryKind<T> {
}
/// The return value of `get_alloc_info` indicates the "kind" of the allocation.
#[derive(Copy, Clone, PartialEq, Debug)]
pub enum AllocKind {
/// A regular live data allocation.
LiveData,
@ -473,8 +474,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
match self.ptr_try_get_alloc_id(ptr) {
Err(addr) => offset_misalignment(addr, align),
Ok((alloc_id, offset, _prov)) => {
let (_size, alloc_align, _kind) = self.get_alloc_info(alloc_id);
if M::use_addr_for_alignment_check(self) {
let (_size, alloc_align, kind) = self.get_alloc_info(alloc_id);
if let Some(misalign) =
M::alignment_check(self, alloc_id, alloc_align, kind, offset, align)
{
Some(misalign)
} else if M::Provenance::OFFSET_IS_ADDR {
// `use_addr_for_alignment_check` can only be true if `OFFSET_IS_ADDR` is true.
offset_misalignment(ptr.addr().bytes(), align)
} else {