From f7d54fa6cb8d5a31914de285efbb79f55b60abb2 Mon Sep 17 00:00:00 2001 From: Ben Kimock Date: Thu, 11 Apr 2024 21:13:57 -0400 Subject: [PATCH] Avoid more NonNull-raw-NonNull roundtrips in Vec --- library/alloc/src/raw_vec.rs | 11 ++++++++ library/alloc/src/vec/in_place_collect.rs | 21 ++++++++------- library/alloc/src/vec/in_place_drop.rs | 7 ++--- library/alloc/src/vec/into_iter.rs | 2 +- library/alloc/src/vec/mod.rs | 27 +++++++++++++++++++ library/alloc/src/vec/spec_from_iter.rs | 2 +- tests/ui/suggestions/deref-path-method.stderr | 2 +- tests/ui/ufcs/bad-builder.stderr | 2 +- 8 files changed, 57 insertions(+), 17 deletions(-) diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs index 0883080d735..1134c7f833e 100644 --- a/library/alloc/src/raw_vec.rs +++ b/library/alloc/src/raw_vec.rs @@ -259,6 +259,17 @@ impl RawVec { Self { ptr: unsafe { Unique::new_unchecked(ptr) }, cap, alloc } } + /// A convenience method for hoisting the non-null precondition out of [`RawVec::from_raw_parts_in`]. + /// + /// # Safety + /// + /// See [`RawVec::from_raw_parts_in`]. + #[inline] + pub(crate) unsafe fn from_nonnull_in(ptr: NonNull, capacity: usize, alloc: A) -> Self { + let cap = if T::IS_ZST { Cap::ZERO } else { unsafe { Cap(capacity) } }; + Self { ptr: Unique::from(ptr), cap, alloc } + } + /// Gets a raw pointer to the start of the allocation. Note that this is /// `Unique::dangling()` if `capacity == 0` or `T` is zero-sized. In the former case, you must /// be careful. diff --git a/library/alloc/src/vec/in_place_collect.rs b/library/alloc/src/vec/in_place_collect.rs index 4907a45e881..88aa1b1b0e0 100644 --- a/library/alloc/src/vec/in_place_collect.rs +++ b/library/alloc/src/vec/in_place_collect.rs @@ -161,7 +161,7 @@ use core::iter::{InPlaceIterable, SourceIter, TrustedRandomAccessNoCoerce}; use core::marker::PhantomData; use core::mem::{self, ManuallyDrop, SizedTypeProperties}; use core::num::NonZero; -use core::ptr::{self, NonNull}; +use core::ptr; use super::{InPlaceDrop, InPlaceDstDataSrcBufDrop, SpecFromIter, SpecFromIterNested, Vec}; @@ -254,28 +254,30 @@ where let (src_buf, src_ptr, src_cap, mut dst_buf, dst_end, dst_cap) = unsafe { let inner = iterator.as_inner().as_into_iter(); ( - inner.buf.as_ptr(), + inner.buf, inner.ptr, inner.cap, - inner.buf.as_ptr() as *mut T, + inner.buf.cast::(), inner.end as *const T, inner.cap * mem::size_of::() / mem::size_of::(), ) }; // SAFETY: `dst_buf` and `dst_end` are the start and end of the buffer. - let len = unsafe { SpecInPlaceCollect::collect_in_place(&mut iterator, dst_buf, dst_end) }; + let len = unsafe { + SpecInPlaceCollect::collect_in_place(&mut iterator, dst_buf.as_ptr() as *mut T, dst_end) + }; let src = unsafe { iterator.as_inner().as_into_iter() }; // check if SourceIter contract was upheld // caveat: if they weren't we might not even make it to this point - debug_assert_eq!(src_buf, src.buf.as_ptr()); + debug_assert_eq!(src_buf, src.buf); // check InPlaceIterable contract. This is only possible if the iterator advanced the // source pointer at all. If it uses unchecked access via TrustedRandomAccess // then the source pointer will stay in its initial position and we can't use it as reference if src.ptr != src_ptr { debug_assert!( - unsafe { dst_buf.add(len) as *const _ } <= src.ptr.as_ptr(), + unsafe { dst_buf.add(len).cast() } <= src.ptr, "InPlaceIterable contract violation, write pointer advanced beyond read pointer" ); } @@ -315,10 +317,9 @@ where let dst_size = mem::size_of::().unchecked_mul(dst_cap); let new_layout = Layout::from_size_align_unchecked(dst_size, dst_align); - let result = - alloc.shrink(NonNull::new_unchecked(dst_buf as *mut u8), old_layout, new_layout); + let result = alloc.shrink(dst_buf.cast(), old_layout, new_layout); let Ok(reallocated) = result else { handle_alloc_error(new_layout) }; - dst_buf = reallocated.as_ptr() as *mut T; + dst_buf = reallocated.cast::(); } } else { debug_assert_eq!(src_cap * mem::size_of::(), dst_cap * mem::size_of::()); @@ -326,7 +327,7 @@ where mem::forget(dst_guard); - let vec = unsafe { Vec::from_raw_parts(dst_buf, len, dst_cap) }; + let vec = unsafe { Vec::from_nonnull(dst_buf, len, dst_cap) }; vec } diff --git a/library/alloc/src/vec/in_place_drop.rs b/library/alloc/src/vec/in_place_drop.rs index 40a540b57fc..4050c250130 100644 --- a/library/alloc/src/vec/in_place_drop.rs +++ b/library/alloc/src/vec/in_place_drop.rs @@ -1,4 +1,5 @@ use core::marker::PhantomData; +use core::ptr::NonNull; use core::ptr::{self, drop_in_place}; use core::slice::{self}; @@ -31,7 +32,7 @@ impl Drop for InPlaceDrop { // the source allocation - i.e. before the reallocation happened - to avoid leaking them // if some other destructor panics. pub(super) struct InPlaceDstDataSrcBufDrop { - pub(super) ptr: *mut Dest, + pub(super) ptr: NonNull, pub(super) len: usize, pub(super) src_cap: usize, pub(super) src: PhantomData, @@ -42,8 +43,8 @@ impl Drop for InPlaceDstDataSrcBufDrop { fn drop(&mut self) { unsafe { let _drop_allocation = - RawVec::::from_raw_parts_in(self.ptr.cast::(), self.src_cap, Global); - drop_in_place(core::ptr::slice_from_raw_parts_mut::(self.ptr, self.len)); + RawVec::::from_nonnull_in(self.ptr.cast::(), self.src_cap, Global); + drop_in_place(core::ptr::slice_from_raw_parts_mut::(self.ptr.as_ptr(), self.len)); }; } } diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs index dfd42ca0619..b0226c84833 100644 --- a/library/alloc/src/vec/into_iter.rs +++ b/library/alloc/src/vec/into_iter.rs @@ -433,7 +433,7 @@ unsafe impl<#[may_dangle] T, A: Allocator> Drop for IntoIter { // `IntoIter::alloc` is not used anymore after this and will be dropped by RawVec let alloc = ManuallyDrop::take(&mut self.0.alloc); // RawVec handles deallocation - let _ = RawVec::from_raw_parts_in(self.0.buf.as_ptr(), self.0.cap, alloc); + let _ = RawVec::from_nonnull_in(self.0.buf, self.0.cap, alloc); } } } diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs index 7e3463bc082..465da39f184 100644 --- a/library/alloc/src/vec/mod.rs +++ b/library/alloc/src/vec/mod.rs @@ -603,6 +603,17 @@ impl Vec { pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Self { unsafe { Self::from_raw_parts_in(ptr, length, capacity, Global) } } + + /// A convenience method for hoisting the non-null precondition out of [`Vec::from_raw_parts`]. + /// + /// # Safety + /// + /// See [`Vec::from_raw_parts`]. + #[inline] + #[cfg(not(no_global_oom_handling))] // required by tests/run-make/alloc-no-oom-handling + pub(crate) unsafe fn from_nonnull(ptr: NonNull, length: usize, capacity: usize) -> Self { + unsafe { Self::from_nonnull_in(ptr, length, capacity, Global) } + } } impl Vec { @@ -820,6 +831,22 @@ impl Vec { unsafe { Vec { buf: RawVec::from_raw_parts_in(ptr, capacity, alloc), len: length } } } + /// A convenience method for hoisting the non-null precondition out of [`Vec::from_raw_parts_in`]. + /// + /// # Safety + /// + /// See [`Vec::from_raw_parts_in`]. + #[inline] + #[cfg(not(no_global_oom_handling))] // required by tests/run-make/alloc-no-oom-handling + pub(crate) unsafe fn from_nonnull_in( + ptr: NonNull, + length: usize, + capacity: usize, + alloc: A, + ) -> Self { + unsafe { Vec { buf: RawVec::from_nonnull_in(ptr, capacity, alloc), len: length } } + } + /// Decomposes a `Vec` into its raw components: `(pointer, length, capacity)`. /// /// Returns the raw pointer to the underlying data, the length of diff --git a/library/alloc/src/vec/spec_from_iter.rs b/library/alloc/src/vec/spec_from_iter.rs index 33dd4139bc0..6646ae7bccb 100644 --- a/library/alloc/src/vec/spec_from_iter.rs +++ b/library/alloc/src/vec/spec_from_iter.rs @@ -51,7 +51,7 @@ impl SpecFromIter> for Vec { if has_advanced { ptr::copy(it.ptr.as_ptr(), it.buf.as_ptr(), it.len()); } - return Vec::from_raw_parts(it.buf.as_ptr(), it.len(), it.cap); + return Vec::from_nonnull(it.buf, it.len(), it.cap); } } diff --git a/tests/ui/suggestions/deref-path-method.stderr b/tests/ui/suggestions/deref-path-method.stderr index b27d9aef066..bfcc2307fd7 100644 --- a/tests/ui/suggestions/deref-path-method.stderr +++ b/tests/ui/suggestions/deref-path-method.stderr @@ -9,7 +9,7 @@ note: if you're trying to build a new `Vec<_, _>` consider using one of the foll Vec::::with_capacity Vec::::try_with_capacity Vec::::from_raw_parts - and 4 others + and 6 others --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL help: the function `contains` is implemented on `[_]` | diff --git a/tests/ui/ufcs/bad-builder.stderr b/tests/ui/ufcs/bad-builder.stderr index 9cfeb7a5d09..e466f94d0d8 100644 --- a/tests/ui/ufcs/bad-builder.stderr +++ b/tests/ui/ufcs/bad-builder.stderr @@ -9,7 +9,7 @@ note: if you're trying to build a new `Vec` consider using one of the followi Vec::::with_capacity Vec::::try_with_capacity Vec::::from_raw_parts - and 4 others + and 6 others --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL help: there is an associated function `new` with a similar name |