Rollup merge of rust-lang#75152 - TimDiekmann:replace_memblock, r=Ama…

…nieu

Replace `Memoryblock` with `NonNull<[u8]>`

Closes rust-lang/wg-allocators#61

r? @Amanieu

library/alloc/src/alloc.rs

@@ -164,27 +164,27 @@ pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
 #[unstable(feature = "allocator_api", issue = "32838")]
 unsafe impl AllocRef for Global {
     #[inline]
-    fn alloc(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
+    fn alloc(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
         let size = layout.size();
         let ptr = if size == 0 {
             layout.dangling()
         } else {
             // SAFETY: `layout` is non-zero in size,
             unsafe { NonNull::new(alloc(layout)).ok_or(AllocErr)? }
         };
-        Ok(MemoryBlock { ptr, size })
+        Ok(NonNull::slice_from_raw_parts(ptr, size))
     }
 
     #[inline]
-    fn alloc_zeroed(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
+    fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
         let size = layout.size();
         let ptr = if size == 0 {
             layout.dangling()
         } else {
             // SAFETY: `layout` is non-zero in size,
             unsafe { NonNull::new(alloc_zeroed(layout)).ok_or(AllocErr)? }
         };
-        Ok(MemoryBlock { ptr, size })
+        Ok(NonNull::slice_from_raw_parts(ptr, size))
     }
 
     #[inline]
@@ -202,7 +202,7 @@ unsafe impl AllocRef for Global {
         ptr: NonNull<u8>,
         layout: Layout,
         new_size: usize,
-    ) -> Result<MemoryBlock, AllocErr> {
+    ) -> Result<NonNull<[u8]>, AllocErr> {
         debug_assert!(
             new_size >= layout.size(),
             "`new_size` must be greater than or equal to `layout.size()`"
@@ -212,14 +212,16 @@ unsafe impl AllocRef for Global {
         // Other conditions must be upheld by the caller
         unsafe {
             match layout.size() {
-                old_size if old_size == new_size => Ok(MemoryBlock { ptr, size: new_size }),
+                old_size if old_size == new_size => {
+                    Ok(NonNull::slice_from_raw_parts(ptr, new_size))
+                }
                 0 => self.alloc(Layout::from_size_align_unchecked(new_size, layout.align())),
                 old_size => {
                     // `realloc` probably checks for `new_size > size` or something similar.
                     intrinsics::assume(new_size > old_size);
                     let raw_ptr = realloc(ptr.as_ptr(), layout, new_size);
                     let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?;
-                    Ok(MemoryBlock { ptr, size: new_size })
+                    Ok(NonNull::slice_from_raw_parts(ptr, new_size))
                 }
             }
         }
@@ -231,7 +233,7 @@ unsafe impl AllocRef for Global {
         ptr: NonNull<u8>,
         layout: Layout,
         new_size: usize,
-    ) -> Result<MemoryBlock, AllocErr> {
+    ) -> Result<NonNull<[u8]>, AllocErr> {
         debug_assert!(
             new_size >= layout.size(),
             "`new_size` must be greater than or equal to `layout.size()`"
@@ -241,15 +243,17 @@ unsafe impl AllocRef for Global {
         // Other conditions must be upheld by the caller
         unsafe {
             match layout.size() {
-                old_size if old_size == new_size => Ok(MemoryBlock { ptr, size: new_size }),
+                old_size if old_size == new_size => {
+                    Ok(NonNull::slice_from_raw_parts(ptr, new_size))
+                }
                 0 => self.alloc_zeroed(Layout::from_size_align_unchecked(new_size, layout.align())),
                 old_size => {
                     // `realloc` probably checks for `new_size > size` or something similar.
                     intrinsics::assume(new_size > old_size);
                     let raw_ptr = realloc(ptr.as_ptr(), layout, new_size);
                     raw_ptr.add(old_size).write_bytes(0, new_size - old_size);
                     let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?;
-                    Ok(MemoryBlock { ptr, size: new_size })
+                    Ok(NonNull::slice_from_raw_parts(ptr, new_size))
                 }
             }
         }
@@ -261,7 +265,7 @@ unsafe impl AllocRef for Global {
         ptr: NonNull<u8>,
         layout: Layout,
         new_size: usize,
-    ) -> Result<MemoryBlock, AllocErr> {
+    ) -> Result<NonNull<[u8]>, AllocErr> {
         let old_size = layout.size();
         debug_assert!(
             new_size <= old_size,
@@ -288,7 +292,7 @@ unsafe impl AllocRef for Global {
             NonNull::new(raw_ptr).ok_or(AllocErr)?
         };
 
-        Ok(MemoryBlock { ptr, size: new_size })
+        Ok(NonNull::slice_from_raw_parts(ptr, new_size))
     }
 }
 
@@ -300,7 +304,7 @@ unsafe impl AllocRef for Global {
 unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
     let layout = unsafe { Layout::from_size_align_unchecked(size, align) };
     match Global.alloc(layout) {
-        Ok(memory) => memory.ptr.as_ptr(),
+        Ok(ptr) => ptr.as_non_null_ptr().as_ptr(),
         Err(_) => handle_alloc_error(layout),
     }
 }

library/alloc/src/alloc/tests.rs

@@ -8,16 +8,16 @@ use test::Bencher;
 fn allocate_zeroed() {
     unsafe {
         let layout = Layout::from_size_align(1024, 1).unwrap();
-        let memory =
+        let ptr =
             Global.alloc_zeroed(layout.clone()).unwrap_or_else(|_| handle_alloc_error(layout));
 
-        let mut i = memory.ptr.cast::<u8>().as_ptr();
+        let mut i = ptr.as_non_null_ptr().as_ptr();
         let end = i.add(layout.size());
         while i < end {
             assert_eq!(*i, 0);
             i = i.offset(1);
         }
-        Global.dealloc(memory.ptr, layout);
+        Global.dealloc(ptr.as_non_null_ptr(), layout);
     }
 }
 

library/alloc/src/boxed.rs

@@ -197,8 +197,7 @@ impl<T> Box<T> {
     #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {
         let layout = alloc::Layout::new::<mem::MaybeUninit<T>>();
-        let ptr =
-            Global.alloc(layout).unwrap_or_else(|_| alloc::handle_alloc_error(layout)).ptr.cast();
+        let ptr = Global.alloc(layout).unwrap_or_else(|_| alloc::handle_alloc_error(layout)).cast();
         unsafe { Box::from_raw(ptr.as_ptr()) }
     }
 
@@ -226,7 +225,6 @@ impl<T> Box<T> {
         let ptr = Global
             .alloc_zeroed(layout)
             .unwrap_or_else(|_| alloc::handle_alloc_error(layout))
-            .ptr
             .cast();
         unsafe { Box::from_raw(ptr.as_ptr()) }
     }

library/alloc/src/lib.rs

@@ -104,6 +104,7 @@
 #![feature(negative_impls)]
 #![feature(new_uninit)]
 #![feature(nll)]
+#![feature(nonnull_slice_from_raw_parts)]
 #![feature(optin_builtin_traits)]
 #![feature(or_patterns)]
 #![feature(pattern)]
@@ -113,6 +114,8 @@
 #![feature(rustc_attrs)]
 #![feature(receiver_trait)]
 #![feature(min_specialization)]
+#![feature(slice_ptr_get)]
+#![feature(slice_ptr_len)]
 #![feature(staged_api)]
 #![feature(std_internals)]
 #![feature(str_internals)]

library/alloc/src/raw_vec.rs

@@ -1,7 +1,7 @@
 #![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "none")]
 #![doc(hidden)]
 
-use core::alloc::{LayoutErr, MemoryBlock};
+use core::alloc::LayoutErr;
 use core::cmp;
 use core::mem::{self, ManuallyDrop, MaybeUninit};
 use core::ops::Drop;
@@ -186,14 +186,14 @@ impl<T, A: AllocRef> RawVec<T, A> {
                 AllocInit::Uninitialized => alloc.alloc(layout),
                 AllocInit::Zeroed => alloc.alloc_zeroed(layout),
             };
-            let memory = match result {
-                Ok(memory) => memory,
+            let ptr = match result {
+                Ok(ptr) => ptr,
                 Err(_) => handle_alloc_error(layout),
             };
 
             Self {
-                ptr: unsafe { Unique::new_unchecked(memory.ptr.cast().as_ptr()) },
-                cap: Self::capacity_from_bytes(memory.size),
+                ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
+                cap: Self::capacity_from_bytes(ptr.len()),
                 alloc,
             }
         }
@@ -384,9 +384,9 @@ impl<T, A: AllocRef> RawVec<T, A> {
         excess / mem::size_of::<T>()
     }
 
-    fn set_memory(&mut self, memory: MemoryBlock) {
-        self.ptr = unsafe { Unique::new_unchecked(memory.ptr.cast().as_ptr()) };
-        self.cap = Self::capacity_from_bytes(memory.size);
+    fn set_ptr(&mut self, ptr: NonNull<[u8]>) {
+        self.ptr = unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) };
+        self.cap = Self::capacity_from_bytes(ptr.len());
     }
 
     // This method is usually instantiated many times. So we want it to be as
@@ -432,8 +432,8 @@ impl<T, A: AllocRef> RawVec<T, A> {
         let new_layout = Layout::array::<T>(cap);
 
         // `finish_grow` is non-generic over `T`.
-        let memory = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
-        self.set_memory(memory);
+        let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
+        self.set_ptr(ptr);
         Ok(())
     }
 
@@ -451,8 +451,8 @@ impl<T, A: AllocRef> RawVec<T, A> {
         let new_layout = Layout::array::<T>(cap);
 
         // `finish_grow` is non-generic over `T`.
-        let memory = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
-        self.set_memory(memory);
+        let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
+        self.set_ptr(ptr);
         Ok(())
     }
 
@@ -462,13 +462,13 @@ impl<T, A: AllocRef> RawVec<T, A> {
         let (ptr, layout) = if let Some(mem) = self.current_memory() { mem } else { return Ok(()) };
         let new_size = amount * mem::size_of::<T>();
 
-        let memory = unsafe {
+        let ptr = unsafe {
             self.alloc.shrink(ptr, layout, new_size).map_err(|_| TryReserveError::AllocError {
                 layout: Layout::from_size_align_unchecked(new_size, layout.align()),
                 non_exhaustive: (),
             })?
         };
-        self.set_memory(memory);
+        self.set_ptr(ptr);
         Ok(())
     }
 }
@@ -481,7 +481,7 @@ fn finish_grow<A>(
     new_layout: Result<Layout, LayoutErr>,
     current_memory: Option<(NonNull<u8>, Layout)>,
     alloc: &mut A,
-) -> Result<MemoryBlock, TryReserveError>
+) -> Result<NonNull<[u8]>, TryReserveError>
 where
     A: AllocRef,
 {

library/alloc/src/raw_vec/tests.rs

@@ -20,7 +20,7 @@ fn allocator_param() {
         fuel: usize,
     }
     unsafe impl AllocRef for BoundedAlloc {
-        fn alloc(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
+        fn alloc(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
             let size = layout.size();
             if size > self.fuel {
                 return Err(AllocErr);

library/alloc/src/rc.rs

@@ -928,10 +928,10 @@ impl<T: ?Sized> Rc<T> {
         let layout = Layout::new::<RcBox<()>>().extend(value_layout).unwrap().0.pad_to_align();
 
         // Allocate for the layout.
-        let mem = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
+        let ptr = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
 
         // Initialize the RcBox
-        let inner = mem_to_rcbox(mem.ptr.as_ptr());
+        let inner = mem_to_rcbox(ptr.as_non_null_ptr().as_ptr());
         unsafe {
             debug_assert_eq!(Layout::for_value(&*inner), layout);
 

library/alloc/src/sync.rs

@@ -883,10 +883,10 @@ impl<T: ?Sized> Arc<T> {
         // reference (see #54908).
         let layout = Layout::new::<ArcInner<()>>().extend(value_layout).unwrap().0.pad_to_align();
 
-        let mem = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
+        let ptr = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
 
         // Initialize the ArcInner
-        let inner = mem_to_arcinner(mem.ptr.as_ptr());
+        let inner = mem_to_arcinner(ptr.as_non_null_ptr().as_ptr());
         debug_assert_eq!(unsafe { Layout::for_value(&*inner) }, layout);
 
         unsafe {
@@ -986,7 +986,7 @@ impl<T> Arc<[T]> {
                     let slice = from_raw_parts_mut(self.elems, self.n_elems);
                     ptr::drop_in_place(slice);
 
-                    Global.dealloc(self.mem.cast(), self.layout);
+                    Global.dealloc(self.mem, self.layout);
                 }
             }
         }

library/alloc/tests/heap.rs

@@ -20,20 +20,23 @@ fn check_overalign_requests<T: AllocRef>(mut allocator: T) {
             unsafe {
                 let pointers: Vec<_> = (0..iterations)
                     .map(|_| {
-                        allocator.alloc(Layout::from_size_align(size, align).unwrap()).unwrap().ptr
+                        allocator.alloc(Layout::from_size_align(size, align).unwrap()).unwrap()
                     })
                     .collect();
                 for &ptr in &pointers {
                     assert_eq!(
-                        (ptr.as_ptr() as usize) % align,
+                        (ptr.as_non_null_ptr().as_ptr() as usize) % align,
                         0,
                         "Got a pointer less aligned than requested"
                     )
                 }
 
                 // Clean up
                 for &ptr in &pointers {
-                    allocator.dealloc(ptr, Layout::from_size_align(size, align).unwrap())
+                    allocator.dealloc(
+                        ptr.as_non_null_ptr(),
+                        Layout::from_size_align(size, align).unwrap(),
+                    )
                 }
             }
         }

library/alloc/tests/lib.rs

@@ -13,6 +13,7 @@
 #![feature(associated_type_bounds)]
 #![feature(binary_heap_into_iter_sorted)]
 #![feature(binary_heap_drain_sorted)]
+#![feature(slice_ptr_get)]
 #![feature(split_inclusive)]
 #![feature(binary_heap_retain)]