| //! The virtual memory representation of the MIR interpreter. |
| |
| use super::{ |
| Pointer, InterpResult, AllocId, ScalarMaybeUndef, write_target_uint, read_target_uint, Scalar, |
| }; |
| |
| use crate::mir; |
| use crate::ty::layout::{Size, Align}; |
| |
| use rustc_data_structures::sorted_map::SortedMap; |
| use rustc_target::abi::HasDataLayout; |
| use syntax::ast::Mutability; |
| use std::iter; |
| use std::ops::{Range, Deref, DerefMut}; |
| use std::borrow::Cow; |
| |
| // NOTE: When adding new fields, make sure to adjust the `Snapshot` impl in |
| // `src/librustc_mir/interpret/snapshot.rs`. |
| #[derive( |
| Clone, |
| Debug, |
| Eq, |
| PartialEq, |
| PartialOrd, |
| Ord, |
| Hash, |
| RustcEncodable, |
| RustcDecodable, |
| HashStable, |
| )] |
| pub struct Allocation<Tag = (),Extra = ()> { |
| /// The actual bytes of the allocation. |
| /// Note that the bytes of a pointer represent the offset of the pointer. |
| 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. |
| relocations: Relocations<Tag>, |
| /// Denotes which part of this allocation is initialized. |
| undef_mask: UndefMask, |
| /// The size of the allocation. Currently, must always equal `bytes.len()`. |
| pub size: Size, |
| /// The alignment of the allocation to detect unaligned reads. |
| pub align: Align, |
| /// `true` if 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, |
| } |
| |
| pub trait AllocationExtra<Tag>: ::std::fmt::Debug + Clone { |
| // There is no constructor in here because the constructor's type depends |
| // on `MemoryKind`, and making things sufficiently generic leads to painful |
| // inference failure. |
| |
| /// 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(always)] |
| fn memory_read( |
| _alloc: &Allocation<Tag, Self>, |
| _ptr: Pointer<Tag>, |
| _size: Size, |
| ) -> InterpResult<'tcx> { |
| Ok(()) |
| } |
| |
| /// Hook for performing extra checks on a memory write access. |
| #[inline(always)] |
| fn memory_written( |
| _alloc: &mut Allocation<Tag, Self>, |
| _ptr: Pointer<Tag>, |
| _size: Size, |
| ) -> InterpResult<'tcx> { |
| Ok(()) |
| } |
| |
| /// Hook for performing extra checks on a memory deallocation. |
| /// `size` will be the size of the allocation. |
| #[inline(always)] |
| fn memory_deallocated( |
| _alloc: &mut Allocation<Tag, Self>, |
| _ptr: Pointer<Tag>, |
| _size: Size, |
| ) -> InterpResult<'tcx> { |
| Ok(()) |
| } |
| } |
| |
| // For `Tag = ()` and no extra state, we have a trivial implementation. |
| impl AllocationExtra<()> for () { } |
| |
| // The constructors are all without extra; the extra gets added by a machine hook later. |
| impl<Tag> Allocation<Tag> { |
| /// Creates a read-only allocation initialized by the given bytes |
| pub fn from_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>, align: Align) -> Self { |
| let bytes = slice.into().into_owned(); |
| let size = Size::from_bytes(bytes.len() as u64); |
| Self { |
| bytes, |
| relocations: Relocations::new(), |
| undef_mask: UndefMask::new(size, true), |
| size, |
| align, |
| mutability: Mutability::Immutable, |
| extra: (), |
| } |
| } |
| |
| pub fn from_byte_aligned_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>) -> Self { |
| Allocation::from_bytes(slice, Align::from_bytes(1).unwrap()) |
| } |
| |
| 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, false), |
| size, |
| align, |
| mutability: Mutability::Mutable, |
| extra: (), |
| } |
| } |
| } |
| |
| impl Allocation<(), ()> { |
| /// Add Tag and Extra fields |
| pub fn with_tags_and_extra<T, E>( |
| self, |
| mut tagger: impl FnMut(AllocId) -> T, |
| extra: E, |
| ) -> Allocation<T, E> { |
| Allocation { |
| bytes: self.bytes, |
| size: self.size, |
| relocations: Relocations::from_presorted( |
| self.relocations.iter() |
| // The allocations in the relocations (pointers stored *inside* this allocation) |
| // all get the base pointer tag. |
| .map(|&(offset, ((), alloc))| { |
| let tag = tagger(alloc); |
| (offset, (tag, alloc)) |
| }) |
| .collect() |
| ), |
| undef_mask: self.undef_mask, |
| align: self.align, |
| mutability: self.mutability, |
| extra, |
| } |
| } |
| } |
| |
| /// Raw accessors. Provide access to otherwise private bytes. |
| impl<Tag, Extra> Allocation<Tag, Extra> { |
| pub fn len(&self) -> usize { |
| self.size.bytes() as usize |
| } |
| |
| /// Looks at a slice which may describe undefined bytes or describe a relocation. This differs |
| /// from `get_bytes_with_undef_and_ptr` in that it does no relocation checks (even on the |
| /// edges) at all. It further ignores `AllocationExtra` callbacks. |
| /// This must not be used for reads affecting the interpreter execution. |
| pub fn inspect_with_undef_and_ptr_outside_interpreter(&self, range: Range<usize>) -> &[u8] { |
| &self.bytes[range] |
| } |
| |
| /// Returns the undef mask. |
| pub fn undef_mask(&self) -> &UndefMask { |
| &self.undef_mask |
| } |
| |
| /// Returns the relocation list. |
| pub fn relocations(&self) -> &Relocations<Tag> { |
| &self.relocations |
| } |
| } |
| |
| impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx Allocation {} |
| |
| /// Byte accessors. |
| impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> { |
| /// Just a small local helper function to avoid a bit of code repetition. |
| /// Returns the range of this allocation that was meant. |
| #[inline] |
| fn check_bounds( |
| &self, |
| offset: Size, |
| size: Size |
| ) -> Range<usize> { |
| let end = offset + size; // This does overflow checking. |
| assert_eq!( |
| end.bytes() as usize as u64, end.bytes(), |
| "cannot handle this access on this host architecture" |
| ); |
| let end = end.bytes() as usize; |
| assert!( |
| end <= self.len(), |
| "Out-of-bounds access at offset {}, size {} in allocation of size {}", |
| offset.bytes(), size.bytes(), self.len() |
| ); |
| (offset.bytes() as usize)..end |
| } |
| |
| /// The last argument controls whether we error out when there are undefined |
| /// or pointer bytes. You should never call this, call `get_bytes` or |
| /// `get_bytes_with_undef_and_ptr` instead, |
| /// |
| /// This function also guarantees that the resulting pointer will remain stable |
| /// even when new allocations are pushed to the `HashMap`. `copy_repeatedly` relies |
| /// on that. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| fn get_bytes_internal( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| check_defined_and_ptr: bool, |
| ) -> InterpResult<'tcx, &[u8]> |
| { |
| let range = self.check_bounds(ptr.offset, size); |
| |
| if check_defined_and_ptr { |
| self.check_defined(ptr, size)?; |
| self.check_relocations(cx, ptr, size)?; |
| } else { |
| // We still don't want relocations on the *edges*. |
| self.check_relocation_edges(cx, ptr, size)?; |
| } |
| |
| AllocationExtra::memory_read(self, ptr, size)?; |
| |
| Ok(&self.bytes[range]) |
| } |
| |
| /// Checks that these bytes are initialized and not pointer bytes, and then return them |
| /// as a slice. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| #[inline] |
| pub fn get_bytes( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| ) -> InterpResult<'tcx, &[u8]> |
| { |
| self.get_bytes_internal(cx, ptr, size, true) |
| } |
| |
| /// It is the caller's responsibility to handle undefined and pointer bytes. |
| /// However, this still checks that there are no relocations on the *edges*. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| #[inline] |
| pub fn get_bytes_with_undef_and_ptr( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| ) -> InterpResult<'tcx, &[u8]> |
| { |
| self.get_bytes_internal(cx, ptr, size, false) |
| } |
| |
| /// Just calling this already marks everything as defined and removes relocations, |
| /// so be sure to actually put data there! |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| pub fn get_bytes_mut( |
| &mut self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| ) -> InterpResult<'tcx, &mut [u8]> |
| { |
| let range = self.check_bounds(ptr.offset, size); |
| |
| self.mark_definedness(ptr, size, true); |
| self.clear_relocations(cx, ptr, size)?; |
| |
| AllocationExtra::memory_written(self, ptr, size)?; |
| |
| Ok(&mut self.bytes[range]) |
| } |
| } |
| |
| /// Reading and writing. |
| impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> { |
| /// Reads bytes until a `0` is encountered. Will error if the end of the allocation is reached |
| /// before a `0` is found. |
| pub fn read_c_str( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| ) -> InterpResult<'tcx, &[u8]> |
| { |
| assert_eq!(ptr.offset.bytes() as usize as u64, ptr.offset.bytes()); |
| let offset = ptr.offset.bytes() as usize; |
| Ok(match self.bytes[offset..].iter().position(|&c| c == 0) { |
| Some(size) => { |
| let size_with_null = Size::from_bytes((size + 1) as u64); |
| // Go through `get_bytes` for checks and AllocationExtra hooks. |
| // We read the null, so we include it in the request, but we want it removed |
| // from the result, so we do subslicing. |
| &self.get_bytes(cx, ptr, size_with_null)?[..size] |
| } |
| // This includes the case where `offset` is out-of-bounds to begin with. |
| None => throw_unsup!(UnterminatedCString(ptr.erase_tag())), |
| }) |
| } |
| |
| /// Validates that `ptr.offset` and `ptr.offset + size` do not point to the middle of a |
| /// relocation. If `allow_ptr_and_undef` is `false`, also enforces that the memory in the |
| /// given range contains neither relocations nor undef bytes. |
| pub fn check_bytes( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| allow_ptr_and_undef: bool, |
| ) -> InterpResult<'tcx> |
| { |
| // Check bounds and relocations on the edges. |
| self.get_bytes_with_undef_and_ptr(cx, ptr, size)?; |
| // Check undef and ptr. |
| if !allow_ptr_and_undef { |
| self.check_defined(ptr, size)?; |
| self.check_relocations(cx, ptr, size)?; |
| } |
| Ok(()) |
| } |
| |
| /// Writes `src` to the memory starting at `ptr.offset`. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| pub fn write_bytes( |
| &mut self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| src: &[u8], |
| ) -> InterpResult<'tcx> |
| { |
| let bytes = self.get_bytes_mut(cx, ptr, Size::from_bytes(src.len() as u64))?; |
| bytes.clone_from_slice(src); |
| Ok(()) |
| } |
| |
| /// Sets `count` bytes starting at `ptr.offset` with `val`. Basically `memset`. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| pub fn write_repeat( |
| &mut self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| val: u8, |
| count: Size |
| ) -> InterpResult<'tcx> |
| { |
| let bytes = self.get_bytes_mut(cx, ptr, count)?; |
| for b in bytes { |
| *b = val; |
| } |
| Ok(()) |
| } |
| |
| /// Reads a *non-ZST* scalar. |
| /// |
| /// ZSTs can't be read for two reasons: |
| /// * byte-order cannot work with zero-element buffers; |
| /// * in order to obtain a `Pointer`, we need to check for ZSTness anyway due to integer |
| /// pointers being valid for ZSTs. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| pub fn read_scalar( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size |
| ) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> |
| { |
| // `get_bytes_unchecked` tests relocation edges. |
| let bytes = self.get_bytes_with_undef_and_ptr(cx, ptr, size)?; |
| // Undef check happens *after* we established that the alignment is correct. |
| // We must not return `Ok()` for unaligned pointers! |
| if self.check_defined(ptr, size).is_err() { |
| // This inflates undefined bytes to the entire scalar, even if only a few |
| // bytes are undefined. |
| return Ok(ScalarMaybeUndef::Undef); |
| } |
| // Now we do the actual reading. |
| let bits = read_target_uint(cx.data_layout().endian, bytes).unwrap(); |
| // See if we got a pointer. |
| if size != cx.data_layout().pointer_size { |
| // *Now*, we better make sure that the inside is free of relocations too. |
| self.check_relocations(cx, ptr, size)?; |
| } else { |
| match self.relocations.get(&ptr.offset) { |
| Some(&(tag, alloc_id)) => { |
| let ptr = Pointer::new_with_tag(alloc_id, Size::from_bytes(bits as u64), tag); |
| return Ok(ScalarMaybeUndef::Scalar(ptr.into())) |
| } |
| None => {}, |
| } |
| } |
| // We don't. Just return the bits. |
| Ok(ScalarMaybeUndef::Scalar(Scalar::from_uint(bits, size))) |
| } |
| |
| /// Reads a pointer-sized scalar. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| pub fn read_ptr_sized( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| ) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> |
| { |
| self.read_scalar(cx, ptr, cx.data_layout().pointer_size) |
| } |
| |
| /// Writes a *non-ZST* scalar. |
| /// |
| /// ZSTs can't be read for two reasons: |
| /// * byte-order cannot work with zero-element buffers; |
| /// * in order to obtain a `Pointer`, we need to check for ZSTness anyway due to integer |
| /// pointers being valid for ZSTs. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| pub fn write_scalar( |
| &mut self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| val: ScalarMaybeUndef<Tag>, |
| type_size: Size, |
| ) -> InterpResult<'tcx> |
| { |
| let val = match val { |
| ScalarMaybeUndef::Scalar(scalar) => scalar, |
| ScalarMaybeUndef::Undef => { |
| self.mark_definedness(ptr, type_size, false); |
| return Ok(()); |
| }, |
| }; |
| |
| let bytes = match val.to_bits_or_ptr(type_size, cx) { |
| Err(val) => val.offset.bytes() as u128, |
| Ok(data) => data, |
| }; |
| |
| let endian = cx.data_layout().endian; |
| let dst = self.get_bytes_mut(cx, ptr, type_size)?; |
| write_target_uint(endian, dst, bytes).unwrap(); |
| |
| // See if we have to also write a relocation. |
| match val { |
| Scalar::Ptr(val) => { |
| self.relocations.insert( |
| ptr.offset, |
| (val.tag, val.alloc_id), |
| ); |
| } |
| _ => {} |
| } |
| |
| Ok(()) |
| } |
| |
| /// Writes a pointer-sized scalar. |
| /// |
| /// It is the caller's responsibility to check bounds and alignment beforehand. |
| pub fn write_ptr_sized( |
| &mut self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| val: ScalarMaybeUndef<Tag> |
| ) -> InterpResult<'tcx> |
| { |
| let ptr_size = cx.data_layout().pointer_size; |
| self.write_scalar(cx, ptr.into(), val, ptr_size) |
| } |
| } |
| |
| /// Relocations. |
| impl<'tcx, Tag: Copy, Extra> Allocation<Tag, Extra> { |
| /// Returns all relocations overlapping with the given pointer-offset pair. |
| pub fn get_relocations( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| ) -> &[(Size, (Tag, AllocId))] { |
| // We have to go back `pointer_size - 1` bytes, as that one would still overlap with |
| // the beginning of this range. |
| let start = ptr.offset.bytes().saturating_sub(cx.data_layout().pointer_size.bytes() - 1); |
| let end = ptr.offset + size; // This does overflow checking. |
| self.relocations.range(Size::from_bytes(start)..end) |
| } |
| |
| /// Checks that there are no relocations overlapping with the given range. |
| #[inline(always)] |
| fn check_relocations( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| ) -> InterpResult<'tcx> { |
| if self.get_relocations(cx, ptr, size).is_empty() { |
| Ok(()) |
| } else { |
| throw_unsup!(ReadPointerAsBytes) |
| } |
| } |
| |
| /// Removes all relocations inside the given range. |
| /// If there are relocations overlapping with the edges, they |
| /// are removed as well *and* the bytes they cover are marked as |
| /// uninitialized. This is a somewhat odd "spooky action at a distance", |
| /// but it allows strictly more code to run than if we would just error |
| /// immediately in that case. |
| fn clear_relocations( |
| &mut self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| ) -> InterpResult<'tcx> { |
| // Find the start and end of the given range and its outermost relocations. |
| let (first, last) = { |
| // Find all relocations overlapping the given range. |
| let relocations = self.get_relocations(cx, ptr, size); |
| if relocations.is_empty() { |
| return Ok(()); |
| } |
| |
| (relocations.first().unwrap().0, |
| relocations.last().unwrap().0 + cx.data_layout().pointer_size) |
| }; |
| let start = ptr.offset; |
| let end = start + size; |
| |
| // Mark parts of the outermost relocations as undefined if they partially fall outside the |
| // given range. |
| if first < start { |
| self.undef_mask.set_range(first, start, false); |
| } |
| if last > end { |
| self.undef_mask.set_range(end, last, false); |
| } |
| |
| // Forget all the relocations. |
| self.relocations.remove_range(first..last); |
| |
| Ok(()) |
| } |
| |
| /// Errors if there are relocations overlapping with the edges of the |
| /// given memory range. |
| #[inline] |
| fn check_relocation_edges( |
| &self, |
| cx: &impl HasDataLayout, |
| ptr: Pointer<Tag>, |
| size: Size, |
| ) -> InterpResult<'tcx> { |
| self.check_relocations(cx, ptr, Size::ZERO)?; |
| self.check_relocations(cx, ptr.offset(size, cx)?, Size::ZERO)?; |
| Ok(()) |
| } |
| } |
| |
| |
| /// Undefined bytes. |
| impl<'tcx, Tag, Extra> Allocation<Tag, Extra> { |
| /// Checks that a range of bytes is defined. If not, returns the `ReadUndefBytes` |
| /// error which will report the first byte which is undefined. |
| #[inline] |
| fn check_defined(&self, ptr: Pointer<Tag>, size: Size) -> InterpResult<'tcx> { |
| self.undef_mask.is_range_defined( |
| ptr.offset, |
| ptr.offset + size, |
| ).or_else(|idx| throw_unsup!(ReadUndefBytes(idx))) |
| } |
| |
| pub fn mark_definedness( |
| &mut self, |
| ptr: Pointer<Tag>, |
| size: Size, |
| new_state: bool, |
| ) { |
| if size.bytes() == 0 { |
| return; |
| } |
| self.undef_mask.set_range( |
| ptr.offset, |
| ptr.offset + size, |
| new_state, |
| ); |
| } |
| } |
| |
| /// Run-length encoding of the undef mask. |
| /// Used to copy parts of a mask multiple times to another allocation. |
| pub struct AllocationDefinedness { |
| /// The definedness of the first range. |
| initial: bool, |
| /// The lengths of ranges that are run-length encoded. |
| /// The definedness of the ranges alternate starting with `initial`. |
| ranges: smallvec::SmallVec::<[u64; 1]>, |
| } |
| |
| /// Transferring the definedness mask to other allocations. |
| impl<Tag, Extra> Allocation<Tag, Extra> { |
| /// Creates a run-length encoding of the undef mask. |
| pub fn compress_undef_range( |
| &self, |
| src: Pointer<Tag>, |
| size: Size, |
| ) -> AllocationDefinedness { |
| // Since we are copying `size` bytes from `src` to `dest + i * size` (`for i in 0..repeat`), |
| // a naive undef mask copying algorithm would repeatedly have to read the undef mask from |
| // the source and write it to the destination. Even if we optimized the memory accesses, |
| // we'd be doing all of this `repeat` times. |
| // Therefor we precompute a compressed version of the undef mask of the source value and |
| // then write it back `repeat` times without computing any more information from the source. |
| |
| // A precomputed cache for ranges of defined/undefined bits |
| // 0000010010001110 will become |
| // `[5, 1, 2, 1, 3, 3, 1]`, |
| // where each element toggles the state. |
| |
| let mut ranges = smallvec::SmallVec::<[u64; 1]>::new(); |
| let initial = self.undef_mask.get(src.offset); |
| let mut cur_len = 1; |
| let mut cur = initial; |
| |
| for i in 1..size.bytes() { |
| // FIXME: optimize to bitshift the current undef block's bits and read the top bit. |
| if self.undef_mask.get(src.offset + Size::from_bytes(i)) == cur { |
| cur_len += 1; |
| } else { |
| ranges.push(cur_len); |
| cur_len = 1; |
| cur = !cur; |
| } |
| } |
| |
| ranges.push(cur_len); |
| |
| AllocationDefinedness { ranges, initial, } |
| } |
| |
| /// Applies multiple instances of the run-length encoding to the undef mask. |
| pub fn mark_compressed_undef_range( |
| &mut self, |
| defined: &AllocationDefinedness, |
| dest: Pointer<Tag>, |
| size: Size, |
| repeat: u64, |
| ) { |
| // An optimization where we can just overwrite an entire range of definedness bits if |
| // they are going to be uniformly `1` or `0`. |
| if defined.ranges.len() <= 1 { |
| self.undef_mask.set_range_inbounds( |
| dest.offset, |
| dest.offset + size * repeat, |
| defined.initial, |
| ); |
| return; |
| } |
| |
| for mut j in 0..repeat { |
| j *= size.bytes(); |
| j += dest.offset.bytes(); |
| let mut cur = defined.initial; |
| for range in &defined.ranges { |
| let old_j = j; |
| j += range; |
| self.undef_mask.set_range_inbounds( |
| Size::from_bytes(old_j), |
| Size::from_bytes(j), |
| cur, |
| ); |
| cur = !cur; |
| } |
| } |
| } |
| } |
| |
| /// Relocations. |
| #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
| pub struct Relocations<Tag = (), Id = AllocId>(SortedMap<Size, (Tag, Id)>); |
| |
| impl<Tag, Id> Relocations<Tag, Id> { |
| pub fn new() -> Self { |
| Relocations(SortedMap::new()) |
| } |
| |
| // 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)) |
| } |
| } |
| |
| impl<Tag> Deref for Relocations<Tag> { |
| type Target = SortedMap<Size, (Tag, AllocId)>; |
| |
| fn deref(&self) -> &Self::Target { |
| &self.0 |
| } |
| } |
| |
| impl<Tag> DerefMut for Relocations<Tag> { |
| fn deref_mut(&mut self) -> &mut Self::Target { |
| &mut self.0 |
| } |
| } |
| |
| /// A partial, owned list of relocations to transfer into another allocation. |
| pub struct AllocationRelocations<Tag> { |
| relative_relocations: Vec<(Size, (Tag, AllocId))>, |
| } |
| |
| impl<Tag: Copy, Extra> Allocation<Tag, Extra> { |
| pub fn prepare_relocation_copy( |
| &self, |
| cx: &impl HasDataLayout, |
| src: Pointer<Tag>, |
| size: Size, |
| dest: Pointer<Tag>, |
| length: u64, |
| ) -> AllocationRelocations<Tag> { |
| let relocations = self.get_relocations(cx, src, size); |
| if relocations.is_empty() { |
| return AllocationRelocations { relative_relocations: Vec::new() }; |
| } |
| |
| let mut new_relocations = Vec::with_capacity(relocations.len() * (length as usize)); |
| |
| for i in 0..length { |
| new_relocations.extend( |
| relocations |
| .iter() |
| .map(|&(offset, reloc)| { |
| // compute offset for current repetition |
| let dest_offset = dest.offset + (i * size); |
| ( |
| // shift offsets from source allocation to destination allocation |
| offset + dest_offset - src.offset, |
| reloc, |
| ) |
| }) |
| ); |
| } |
| |
| AllocationRelocations { |
| relative_relocations: new_relocations, |
| } |
| } |
| |
| /// Applies a relocation copy. |
| /// The affected range, as defined in the parameters to `prepare_relocation_copy` is expected |
| /// to be clear of relocations. |
| pub fn mark_relocation_range( |
| &mut self, |
| relocations: AllocationRelocations<Tag>, |
| ) { |
| self.relocations.insert_presorted(relocations.relative_relocations); |
| } |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Undefined byte tracking |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| type Block = u64; |
| |
| /// A bitmask where each bit refers to the byte with the same index. If the bit is `true`, the byte |
| /// is defined. If it is `false` the byte is undefined. |
| #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
| pub struct UndefMask { |
| blocks: Vec<Block>, |
| len: Size, |
| } |
| |
| impl_stable_hash_for!(struct mir::interpret::UndefMask{blocks, len}); |
| |
| impl UndefMask { |
| pub const BLOCK_SIZE: u64 = 64; |
| |
| pub fn new(size: Size, state: bool) -> Self { |
| let mut m = UndefMask { |
| blocks: vec![], |
| len: Size::ZERO, |
| }; |
| m.grow(size, state); |
| m |
| } |
| |
| /// Checks 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); |
| } |
| |
| // FIXME(oli-obk): optimize this for allocations larger than a block. |
| let idx = (start.bytes()..end.bytes()) |
| .map(|i| Size::from_bytes(i)) |
| .find(|&i| !self.get(i)); |
| |
| match idx { |
| Some(idx) => Err(idx), |
| None => Ok(()) |
| } |
| } |
| |
| 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); |
| } |
| |
| pub fn set_range_inbounds(&mut self, start: Size, end: Size, new_state: bool) { |
| let (blocka, bita) = bit_index(start); |
| let (blockb, bitb) = bit_index(end); |
| if blocka == blockb { |
| // First set all bits except the first `bita`, |
| // then unset the last `64 - bitb` bits. |
| let range = if bitb == 0 { |
| u64::max_value() << bita |
| } else { |
| (u64::max_value() << bita) & (u64::max_value() >> (64 - bitb)) |
| }; |
| if new_state { |
| self.blocks[blocka] |= range; |
| } else { |
| self.blocks[blocka] &= !range; |
| } |
| return; |
| } |
| // across block boundaries |
| if new_state { |
| // Set `bita..64` to `1`. |
| self.blocks[blocka] |= u64::max_value() << bita; |
| // Set `0..bitb` to `1`. |
| if bitb != 0 { |
| self.blocks[blockb] |= u64::max_value() >> (64 - bitb); |
| } |
| // Fill in all the other blocks (much faster than one bit at a time). |
| for block in (blocka + 1) .. blockb { |
| self.blocks[block] = u64::max_value(); |
| } |
| } else { |
| // Set `bita..64` to `0`. |
| self.blocks[blocka] &= !(u64::max_value() << bita); |
| // Set `0..bitb` to `0`. |
| if bitb != 0 { |
| self.blocks[blockb] &= !(u64::max_value() >> (64 - bitb)); |
| } |
| // Fill in all the other blocks (much faster than one bit at a time). |
| for block in (blocka + 1) .. blockb { |
| self.blocks[block] = 0; |
| } |
| } |
| } |
| |
| #[inline] |
| pub fn get(&self, i: Size) -> bool { |
| let (block, bit) = bit_index(i); |
| (self.blocks[block] & (1 << bit)) != 0 |
| } |
| |
| #[inline] |
| pub fn set(&mut self, i: Size, new_state: bool) { |
| let (block, bit) = bit_index(i); |
| self.set_bit(block, bit, new_state); |
| } |
| |
| #[inline] |
| fn set_bit(&mut self, block: usize, bit: usize, new_state: bool) { |
| if new_state { |
| self.blocks[block] |= 1 << bit; |
| } else { |
| self.blocks[block] &= !(1 << bit); |
| } |
| } |
| |
| pub fn grow(&mut self, amount: Size, new_state: bool) { |
| if amount.bytes() == 0 { |
| return; |
| } |
| let unused_trailing_bits = self.blocks.len() as u64 * Self::BLOCK_SIZE - self.len.bytes(); |
| if amount.bytes() > unused_trailing_bits { |
| let additional_blocks = amount.bytes() / Self::BLOCK_SIZE + 1; |
| assert_eq!(additional_blocks as usize as u64, additional_blocks); |
| self.blocks.extend( |
| // FIXME(oli-obk): optimize this by repeating `new_state as Block`. |
| iter::repeat(0).take(additional_blocks as usize), |
| ); |
| } |
| let start = self.len; |
| self.len += amount; |
| self.set_range_inbounds(start, start + amount, new_state); |
| } |
| } |
| |
| #[inline] |
| fn bit_index(bits: Size) -> (usize, usize) { |
| let bits = bits.bytes(); |
| let a = bits / UndefMask::BLOCK_SIZE; |
| let b = bits % UndefMask::BLOCK_SIZE; |
| assert_eq!(a as usize as u64, a); |
| assert_eq!(b as usize as u64, b); |
| (a as usize, b as usize) |
| } |
