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Miri engine refactoring #55674
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c6404f5
Duplicate mod.rs for better diff tracking
oli-obk 7db0483
Move `Allocation` into its own module
oli-obk 48f6941
Move `ScalarMaybeUndef` back to rustc
oli-obk 6def30b
Move the `memory_accessed` hook onto the `Extra` value
oli-obk 2108b6b
Move UndefMask and Relocations into `allocation.rs`
oli-obk 99ed98b
Move ScalarMaybeUndef into `value.rs`
oli-obk 00e524c
Move `Pointer` to its own module
oli-obk 769ee79
Fallout
oli-obk 5d58a03
Give `AllocationExtra`s access to their entire `Allocation`
oli-obk 428af73
Rebase fallout
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,233 @@ | ||
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT | ||
// file at the top-level directory of this distribution and at | ||
// http://rust-lang.org/COPYRIGHT. | ||
// | ||
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
// option. This file may not be copied, modified, or distributed | ||
// except according to those terms. | ||
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//! The virtual memory representation of the MIR interpreter | ||
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use super::{Pointer, EvalResult, AllocId}; | ||
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use ty::layout::{Size, Align}; | ||
use syntax::ast::Mutability; | ||
use std::iter; | ||
use mir; | ||
use std::ops::{Deref, DerefMut}; | ||
use rustc_data_structures::sorted_map::SortedMap; | ||
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#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] | ||
pub struct Allocation<Tag=(),Extra=()> { | ||
/// The actual bytes of the allocation. | ||
/// Note that the bytes of a pointer represent the offset of the pointer | ||
pub bytes: Vec<u8>, | ||
/// Maps from byte addresses to extra data for each pointer. | ||
/// Only the first byte of a pointer is inserted into the map; i.e., | ||
/// every entry in this map applies to `pointer_size` consecutive bytes starting | ||
/// at the given offset. | ||
pub relocations: Relocations<Tag>, | ||
/// Denotes undefined memory. Reading from undefined memory is forbidden in miri | ||
pub undef_mask: UndefMask, | ||
/// The alignment of the allocation to detect unaligned reads. | ||
pub align: Align, | ||
/// Whether the allocation is mutable. | ||
/// Also used by codegen to determine if a static should be put into mutable memory, | ||
/// which happens for `static mut` and `static` with interior mutability. | ||
pub mutability: Mutability, | ||
/// Extra state for the machine. | ||
pub extra: Extra, | ||
} | ||
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pub trait AllocationExtra<Tag>: ::std::fmt::Debug + Default + Clone { | ||
/// Hook for performing extra checks on a memory read access. | ||
/// | ||
/// Takes read-only access to the allocation so we can keep all the memory read | ||
/// operations take `&self`. Use a `RefCell` in `AllocExtra` if you | ||
/// need to mutate. | ||
#[inline] | ||
fn memory_read( | ||
_alloc: &Allocation<Tag, Self>, | ||
_ptr: Pointer<Tag>, | ||
_size: Size, | ||
) -> EvalResult<'tcx> { | ||
Ok(()) | ||
} | ||
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/// Hook for performing extra checks on a memory write access. | ||
#[inline] | ||
fn memory_written( | ||
_alloc: &mut Allocation<Tag, Self>, | ||
_ptr: Pointer<Tag>, | ||
_size: Size, | ||
) -> EvalResult<'tcx> { | ||
Ok(()) | ||
} | ||
} | ||
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impl AllocationExtra<()> for () {} | ||
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impl<Tag, Extra: Default> Allocation<Tag, Extra> { | ||
/// Creates a read-only allocation initialized by the given bytes | ||
pub fn from_bytes(slice: &[u8], align: Align) -> Self { | ||
let mut undef_mask = UndefMask::new(Size::ZERO); | ||
undef_mask.grow(Size::from_bytes(slice.len() as u64), true); | ||
Self { | ||
bytes: slice.to_owned(), | ||
relocations: Relocations::new(), | ||
undef_mask, | ||
align, | ||
mutability: Mutability::Immutable, | ||
extra: Extra::default(), | ||
} | ||
} | ||
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pub fn from_byte_aligned_bytes(slice: &[u8]) -> Self { | ||
Allocation::from_bytes(slice, Align::from_bytes(1, 1).unwrap()) | ||
} | ||
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pub fn undef(size: Size, align: Align) -> Self { | ||
assert_eq!(size.bytes() as usize as u64, size.bytes()); | ||
Allocation { | ||
bytes: vec![0; size.bytes() as usize], | ||
relocations: Relocations::new(), | ||
undef_mask: UndefMask::new(size), | ||
align, | ||
mutability: Mutability::Mutable, | ||
extra: Extra::default(), | ||
} | ||
} | ||
} | ||
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impl<'tcx> ::serialize::UseSpecializedDecodable for &'tcx Allocation {} | ||
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#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] | ||
pub struct Relocations<Tag=(), Id=AllocId>(SortedMap<Size, (Tag, Id)>); | ||
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impl<Tag, Id> Relocations<Tag, Id> { | ||
pub fn new() -> Self { | ||
Relocations(SortedMap::new()) | ||
} | ||
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// The caller must guarantee that the given relocations are already sorted | ||
// by address and contain no duplicates. | ||
pub fn from_presorted(r: Vec<(Size, (Tag, Id))>) -> Self { | ||
Relocations(SortedMap::from_presorted_elements(r)) | ||
} | ||
} | ||
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impl<Tag> Deref for Relocations<Tag> { | ||
type Target = SortedMap<Size, (Tag, AllocId)>; | ||
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fn deref(&self) -> &Self::Target { | ||
&self.0 | ||
} | ||
} | ||
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impl<Tag> DerefMut for Relocations<Tag> { | ||
fn deref_mut(&mut self) -> &mut Self::Target { | ||
&mut self.0 | ||
} | ||
} | ||
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//////////////////////////////////////////////////////////////////////////////// | ||
// Undefined byte tracking | ||
//////////////////////////////////////////////////////////////////////////////// | ||
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type Block = u64; | ||
const BLOCK_SIZE: u64 = 64; | ||
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#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] | ||
pub struct UndefMask { | ||
blocks: Vec<Block>, | ||
len: Size, | ||
} | ||
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impl_stable_hash_for!(struct mir::interpret::UndefMask{blocks, len}); | ||
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impl UndefMask { | ||
pub fn new(size: Size) -> Self { | ||
let mut m = UndefMask { | ||
blocks: vec![], | ||
len: Size::ZERO, | ||
}; | ||
m.grow(size, false); | ||
m | ||
} | ||
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/// Check whether the range `start..end` (end-exclusive) is entirely defined. | ||
/// | ||
/// Returns `Ok(())` if it's defined. Otherwise returns the index of the byte | ||
/// at which the first undefined access begins. | ||
#[inline] | ||
pub fn is_range_defined(&self, start: Size, end: Size) -> Result<(), Size> { | ||
if end > self.len { | ||
return Err(self.len); | ||
} | ||
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let idx = (start.bytes()..end.bytes()) | ||
.map(|i| Size::from_bytes(i)) | ||
.find(|&i| !self.get(i)); | ||
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match idx { | ||
Some(idx) => Err(idx), | ||
None => Ok(()) | ||
} | ||
} | ||
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pub fn set_range(&mut self, start: Size, end: Size, new_state: bool) { | ||
let len = self.len; | ||
if end > len { | ||
self.grow(end - len, new_state); | ||
} | ||
self.set_range_inbounds(start, end, new_state); | ||
} | ||
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pub fn set_range_inbounds(&mut self, start: Size, end: Size, new_state: bool) { | ||
for i in start.bytes()..end.bytes() { | ||
self.set(Size::from_bytes(i), new_state); | ||
} | ||
} | ||
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#[inline] | ||
pub fn get(&self, i: Size) -> bool { | ||
let (block, bit) = bit_index(i); | ||
(self.blocks[block] & 1 << bit) != 0 | ||
} | ||
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#[inline] | ||
pub fn set(&mut self, i: Size, new_state: bool) { | ||
let (block, bit) = bit_index(i); | ||
if new_state { | ||
self.blocks[block] |= 1 << bit; | ||
} else { | ||
self.blocks[block] &= !(1 << bit); | ||
} | ||
} | ||
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pub fn grow(&mut self, amount: Size, new_state: bool) { | ||
let unused_trailing_bits = self.blocks.len() as u64 * BLOCK_SIZE - self.len.bytes(); | ||
if amount.bytes() > unused_trailing_bits { | ||
let additional_blocks = amount.bytes() / BLOCK_SIZE + 1; | ||
assert_eq!(additional_blocks as usize as u64, additional_blocks); | ||
self.blocks.extend( | ||
iter::repeat(0).take(additional_blocks as usize), | ||
); | ||
} | ||
let start = self.len; | ||
self.len += amount; | ||
self.set_range_inbounds(start, start + amount, new_state); | ||
} | ||
} | ||
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#[inline] | ||
fn bit_index(bits: Size) -> (usize, usize) { | ||
let bits = bits.bytes(); | ||
let a = bits / BLOCK_SIZE; | ||
let b = bits % BLOCK_SIZE; | ||
assert_eq!(a as usize as u64, a); | ||
assert_eq!(b as usize as u64, b); | ||
(a as usize, b as usize) | ||
} |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,151 @@ | ||
use mir; | ||
use ty::layout::{self, HasDataLayout, Size}; | ||
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use super::{ | ||
AllocId, EvalResult, | ||
}; | ||
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//////////////////////////////////////////////////////////////////////////////// | ||
// Pointer arithmetic | ||
//////////////////////////////////////////////////////////////////////////////// | ||
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pub trait PointerArithmetic: layout::HasDataLayout { | ||
// These are not supposed to be overridden. | ||
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#[inline(always)] | ||
fn pointer_size(&self) -> Size { | ||
self.data_layout().pointer_size | ||
} | ||
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//// Trunace the given value to the pointer size; also return whether there was an overflow | ||
#[inline] | ||
fn truncate_to_ptr(&self, val: u128) -> (u64, bool) { | ||
let max_ptr_plus_1 = 1u128 << self.pointer_size().bits(); | ||
((val % max_ptr_plus_1) as u64, val >= max_ptr_plus_1) | ||
} | ||
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#[inline] | ||
fn offset<'tcx>(&self, val: u64, i: u64) -> EvalResult<'tcx, u64> { | ||
let (res, over) = self.overflowing_offset(val, i); | ||
if over { err!(Overflow(mir::BinOp::Add)) } else { Ok(res) } | ||
} | ||
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#[inline] | ||
fn overflowing_offset(&self, val: u64, i: u64) -> (u64, bool) { | ||
let (res, over1) = val.overflowing_add(i); | ||
let (res, over2) = self.truncate_to_ptr(u128::from(res)); | ||
(res, over1 || over2) | ||
} | ||
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#[inline] | ||
fn signed_offset<'tcx>(&self, val: u64, i: i64) -> EvalResult<'tcx, u64> { | ||
let (res, over) = self.overflowing_signed_offset(val, i128::from(i)); | ||
if over { err!(Overflow(mir::BinOp::Add)) } else { Ok(res) } | ||
} | ||
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// Overflow checking only works properly on the range from -u64 to +u64. | ||
#[inline] | ||
fn overflowing_signed_offset(&self, val: u64, i: i128) -> (u64, bool) { | ||
// FIXME: is it possible to over/underflow here? | ||
if i < 0 { | ||
// trickery to ensure that i64::min_value() works fine | ||
// this formula only works for true negative values, it panics for zero! | ||
let n = u64::max_value() - (i as u64) + 1; | ||
val.overflowing_sub(n) | ||
} else { | ||
self.overflowing_offset(val, i as u64) | ||
} | ||
} | ||
} | ||
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impl<T: layout::HasDataLayout> PointerArithmetic for T {} | ||
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/// Pointer is generic over the type that represents a reference to Allocations, | ||
/// thus making it possible for the most convenient representation to be used in | ||
/// each context. | ||
/// | ||
/// Defaults to the index based and loosely coupled AllocId. | ||
/// | ||
/// Pointer is also generic over the `Tag` associated with each pointer, | ||
/// which is used to do provenance tracking during execution. | ||
#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, RustcEncodable, RustcDecodable, Hash)] | ||
pub struct Pointer<Tag=(),Id=AllocId> { | ||
pub alloc_id: Id, | ||
pub offset: Size, | ||
pub tag: Tag, | ||
} | ||
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/// Produces a `Pointer` which points to the beginning of the Allocation | ||
impl From<AllocId> for Pointer { | ||
#[inline(always)] | ||
fn from(alloc_id: AllocId) -> Self { | ||
Pointer::new(alloc_id, Size::ZERO) | ||
} | ||
} | ||
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impl<'tcx> Pointer<()> { | ||
#[inline(always)] | ||
pub fn new(alloc_id: AllocId, offset: Size) -> Self { | ||
Pointer { alloc_id, offset, tag: () } | ||
} | ||
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#[inline(always)] | ||
pub fn with_default_tag<Tag>(self) -> Pointer<Tag> | ||
where Tag: Default | ||
{ | ||
Pointer::new_with_tag(self.alloc_id, self.offset, Default::default()) | ||
} | ||
} | ||
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impl<'tcx, Tag> Pointer<Tag> { | ||
#[inline(always)] | ||
pub fn new_with_tag(alloc_id: AllocId, offset: Size, tag: Tag) -> Self { | ||
Pointer { alloc_id, offset, tag } | ||
} | ||
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#[inline] | ||
pub fn offset(self, i: Size, cx: &impl HasDataLayout) -> EvalResult<'tcx, Self> { | ||
Ok(Pointer::new_with_tag( | ||
self.alloc_id, | ||
Size::from_bytes(cx.data_layout().offset(self.offset.bytes(), i.bytes())?), | ||
self.tag | ||
)) | ||
} | ||
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#[inline] | ||
pub fn overflowing_offset(self, i: Size, cx: &impl HasDataLayout) -> (Self, bool) { | ||
let (res, over) = cx.data_layout().overflowing_offset(self.offset.bytes(), i.bytes()); | ||
(Pointer::new_with_tag(self.alloc_id, Size::from_bytes(res), self.tag), over) | ||
} | ||
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#[inline(always)] | ||
pub fn wrapping_offset(self, i: Size, cx: &impl HasDataLayout) -> Self { | ||
self.overflowing_offset(i, cx).0 | ||
} | ||
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#[inline] | ||
pub fn signed_offset(self, i: i64, cx: &impl HasDataLayout) -> EvalResult<'tcx, Self> { | ||
Ok(Pointer::new_with_tag( | ||
self.alloc_id, | ||
Size::from_bytes(cx.data_layout().signed_offset(self.offset.bytes(), i)?), | ||
self.tag, | ||
)) | ||
} | ||
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#[inline] | ||
pub fn overflowing_signed_offset(self, i: i128, cx: &impl HasDataLayout) -> (Self, bool) { | ||
let (res, over) = cx.data_layout().overflowing_signed_offset(self.offset.bytes(), i); | ||
(Pointer::new_with_tag(self.alloc_id, Size::from_bytes(res), self.tag), over) | ||
} | ||
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#[inline(always)] | ||
pub fn wrapping_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> Self { | ||
self.overflowing_signed_offset(i128::from(i), cx).0 | ||
} | ||
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#[inline(always)] | ||
pub fn erase_tag(self) -> Pointer { | ||
Pointer { alloc_id: self.alloc_id, offset: self.offset, tag: () } | ||
} | ||
} |
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