diff options
Diffstat (limited to 'rust/alloc/vec/mod.rs')
| -rw-r--r-- | rust/alloc/vec/mod.rs | 81 |
1 files changed, 61 insertions, 20 deletions
diff --git a/rust/alloc/vec/mod.rs b/rust/alloc/vec/mod.rs index 41ca71805ef0..220fb9d6f45b 100644 --- a/rust/alloc/vec/mod.rs +++ b/rust/alloc/vec/mod.rs @@ -105,6 +105,7 @@ mod into_iter; #[cfg(not(no_global_oom_handling))] use self::is_zero::IsZero; +#[cfg(not(no_global_oom_handling))] mod is_zero; #[cfg(not(no_global_oom_handling))] @@ -123,7 +124,7 @@ use self::set_len_on_drop::SetLenOnDrop; mod set_len_on_drop; #[cfg(not(no_global_oom_handling))] -use self::in_place_drop::{InPlaceDrop, InPlaceDstBufDrop}; +use self::in_place_drop::{InPlaceDrop, InPlaceDstDataSrcBufDrop}; #[cfg(not(no_global_oom_handling))] mod in_place_drop; @@ -1376,7 +1377,7 @@ impl<T, A: Allocator> Vec<T, A> { /// [`as_mut_ptr`]: Vec::as_mut_ptr /// [`as_ptr`]: Vec::as_ptr #[stable(feature = "vec_as_ptr", since = "1.37.0")] - #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)] + #[rustc_never_returns_null_ptr] #[inline] pub fn as_ptr(&self) -> *const T { // We shadow the slice method of the same name to avoid going through @@ -1436,7 +1437,7 @@ impl<T, A: Allocator> Vec<T, A> { /// [`as_mut_ptr`]: Vec::as_mut_ptr /// [`as_ptr`]: Vec::as_ptr #[stable(feature = "vec_as_ptr", since = "1.37.0")] - #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)] + #[rustc_never_returns_null_ptr] #[inline] pub fn as_mut_ptr(&mut self) -> *mut T { // We shadow the slice method of the same name to avoid going through @@ -1565,7 +1566,8 @@ impl<T, A: Allocator> Vec<T, A> { #[stable(feature = "rust1", since = "1.0.0")] pub fn swap_remove(&mut self, index: usize) -> T { #[cold] - #[inline(never)] + #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] + #[track_caller] fn assert_failed(index: usize, len: usize) -> ! { panic!("swap_remove index (is {index}) should be < len (is {len})"); } @@ -1606,7 +1608,8 @@ impl<T, A: Allocator> Vec<T, A> { #[stable(feature = "rust1", since = "1.0.0")] pub fn insert(&mut self, index: usize, element: T) { #[cold] - #[inline(never)] + #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] + #[track_caller] fn assert_failed(index: usize, len: usize) -> ! { panic!("insertion index (is {index}) should be <= len (is {len})"); } @@ -1667,7 +1670,7 @@ impl<T, A: Allocator> Vec<T, A> { #[track_caller] pub fn remove(&mut self, index: usize) -> T { #[cold] - #[inline(never)] + #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] #[track_caller] fn assert_failed(index: usize, len: usize) -> ! { panic!("removal index (is {index}) should be < len (is {len})"); @@ -1891,7 +1894,32 @@ impl<T, A: Allocator> Vec<T, A> { return; } - /* INVARIANT: vec.len() > read >= write > write-1 >= 0 */ + // Check if we ever want to remove anything. + // This allows to use copy_non_overlapping in next cycle. + // And avoids any memory writes if we don't need to remove anything. + let mut first_duplicate_idx: usize = 1; + let start = self.as_mut_ptr(); + while first_duplicate_idx != len { + let found_duplicate = unsafe { + // SAFETY: first_duplicate always in range [1..len) + // Note that we start iteration from 1 so we never overflow. + let prev = start.add(first_duplicate_idx.wrapping_sub(1)); + let current = start.add(first_duplicate_idx); + // We explicitly say in docs that references are reversed. + same_bucket(&mut *current, &mut *prev) + }; + if found_duplicate { + break; + } + first_duplicate_idx += 1; + } + // Don't need to remove anything. + // We cannot get bigger than len. + if first_duplicate_idx == len { + return; + } + + /* INVARIANT: vec.len() > read > write > write-1 >= 0 */ struct FillGapOnDrop<'a, T, A: core::alloc::Allocator> { /* Offset of the element we want to check if it is duplicate */ read: usize, @@ -1937,31 +1965,39 @@ impl<T, A: Allocator> Vec<T, A> { } } - let mut gap = FillGapOnDrop { read: 1, write: 1, vec: self }; - let ptr = gap.vec.as_mut_ptr(); - /* Drop items while going through Vec, it should be more efficient than * doing slice partition_dedup + truncate */ + // Construct gap first and then drop item to avoid memory corruption if `T::drop` panics. + let mut gap = + FillGapOnDrop { read: first_duplicate_idx + 1, write: first_duplicate_idx, vec: self }; + unsafe { + // SAFETY: we checked that first_duplicate_idx in bounds before. + // If drop panics, `gap` would remove this item without drop. + ptr::drop_in_place(start.add(first_duplicate_idx)); + } + /* SAFETY: Because of the invariant, read_ptr, prev_ptr and write_ptr * are always in-bounds and read_ptr never aliases prev_ptr */ unsafe { while gap.read < len { - let read_ptr = ptr.add(gap.read); - let prev_ptr = ptr.add(gap.write.wrapping_sub(1)); + let read_ptr = start.add(gap.read); + let prev_ptr = start.add(gap.write.wrapping_sub(1)); - if same_bucket(&mut *read_ptr, &mut *prev_ptr) { + // We explicitly say in docs that references are reversed. + let found_duplicate = same_bucket(&mut *read_ptr, &mut *prev_ptr); + if found_duplicate { // Increase `gap.read` now since the drop may panic. gap.read += 1; /* We have found duplicate, drop it in-place */ ptr::drop_in_place(read_ptr); } else { - let write_ptr = ptr.add(gap.write); + let write_ptr = start.add(gap.write); - /* Because `read_ptr` can be equal to `write_ptr`, we either - * have to use `copy` or conditional `copy_nonoverlapping`. - * Looks like the first option is faster. */ - ptr::copy(read_ptr, write_ptr, 1); + /* read_ptr cannot be equal to write_ptr because at this point + * we guaranteed to skip at least one element (before loop starts). + */ + ptr::copy_nonoverlapping(read_ptr, write_ptr, 1); /* We have filled that place, so go further */ gap.write += 1; @@ -2097,6 +2133,7 @@ impl<T, A: Allocator> Vec<T, A> { } else { unsafe { self.len -= 1; + core::intrinsics::assume(self.len < self.capacity()); Some(ptr::read(self.as_ptr().add(self.len()))) } } @@ -2299,7 +2336,8 @@ impl<T, A: Allocator> Vec<T, A> { A: Clone, { #[cold] - #[inline(never)] + #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] + #[track_caller] fn assert_failed(at: usize, len: usize) -> ! { panic!("`at` split index (is {at}) should be <= len (is {len})"); } @@ -2840,6 +2878,7 @@ pub fn from_elem_in<T: Clone, A: Allocator>(elem: T, n: usize, alloc: A) -> Vec< <T as SpecFromElem>::from_elem(elem, n, alloc) } +#[cfg(not(no_global_oom_handling))] trait ExtendFromWithinSpec { /// # Safety /// @@ -2848,6 +2887,7 @@ trait ExtendFromWithinSpec { unsafe fn spec_extend_from_within(&mut self, src: Range<usize>); } +#[cfg(not(no_global_oom_handling))] impl<T: Clone, A: Allocator> ExtendFromWithinSpec for Vec<T, A> { default unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) { // SAFETY: @@ -2867,6 +2907,7 @@ impl<T: Clone, A: Allocator> ExtendFromWithinSpec for Vec<T, A> { } } +#[cfg(not(no_global_oom_handling))] impl<T: Copy, A: Allocator> ExtendFromWithinSpec for Vec<T, A> { unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) { let count = src.len(); @@ -2947,7 +2988,7 @@ impl<T: Clone, A: Allocator + Clone> Clone for Vec<T, A> { /// ``` /// use std::hash::BuildHasher; /// -/// let b = std::collections::hash_map::RandomState::new(); +/// let b = std::hash::RandomState::new(); /// let v: Vec<u8> = vec![0xa8, 0x3c, 0x09]; /// let s: &[u8] = &[0xa8, 0x3c, 0x09]; /// assert_eq!(b.hash_one(v), b.hash_one(s)); |