diff --git a/library/std/src/sys/alloc/windows.rs b/library/std/src/sys/alloc/windows.rs index a77dda6e817..7e2402afab9 100644 --- a/library/std/src/sys/alloc/windows.rs +++ b/library/std/src/sys/alloc/windows.rs @@ -3,7 +3,6 @@ use crate::alloc::{GlobalAlloc, Layout, System}; use crate::ffi::c_void; use crate::mem::MaybeUninit; use crate::ptr; -use crate::sync::atomic::{AtomicPtr, Ordering}; use crate::sys::c; #[cfg(test)] @@ -81,45 +80,9 @@ windows_targets::link!("kernel32.dll" "system" fn HeapReAlloc( // See https://docs.microsoft.com/windows/win32/api/heapapi/nf-heapapi-heapfree windows_targets::link!("kernel32.dll" "system" fn HeapFree(hheap: c::HANDLE, dwflags: u32, lpmem: *const c_void) -> c::BOOL); -// Cached handle to the default heap of the current process. -// Either a non-null handle returned by `GetProcessHeap`, or null when not yet initialized or `GetProcessHeap` failed. -static HEAP: AtomicPtr = AtomicPtr::new(ptr::null_mut()); - -// Get a handle to the default heap of the current process, or null if the operation fails. -// If this operation is successful, `HEAP` will be successfully initialized and contain -// a non-null handle returned by `GetProcessHeap`. -#[inline] -fn init_or_get_process_heap() -> c::HANDLE { - // `HEAP` has not yet been successfully initialized - let heap = unsafe { GetProcessHeap() }; - if !heap.is_null() { - // SAFETY: No locking is needed because within the same process, - // successful calls to `GetProcessHeap` will always return the same value, even on different threads. - HEAP.store(heap, Ordering::Release); - - // SAFETY: `HEAP` contains a non-null handle returned by `GetProcessHeap` - heap - } else { - // Could not get the current process heap. - ptr::null_mut() - } -} - -/// This is outlined from `process_heap_alloc` so that `process_heap_alloc` -/// does not need any stack allocations. -#[inline(never)] -#[cold] -extern "C" fn process_heap_init_and_alloc( - _heap: MaybeUninit, // We pass this argument to match the ABI of `HeapAlloc` - flags: u32, - bytes: usize, -) -> *mut c_void { - let heap = init_or_get_process_heap(); - if core::intrinsics::unlikely(heap.is_null()) { - return ptr::null_mut(); - } - // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`. - unsafe { HeapAlloc(heap, flags, bytes) } +fn get_process_heap() -> *mut c_void { + // SAFETY: GetProcessHeap simply returns a valid handle or NULL so is always safe to call. + unsafe { GetProcessHeap() } } #[inline(never)] @@ -128,20 +91,12 @@ fn process_heap_alloc( flags: u32, bytes: usize, ) -> *mut c_void { - let heap = HEAP.load(Ordering::Relaxed); - if core::intrinsics::likely(!heap.is_null()) { - // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`. - unsafe { HeapAlloc(heap, flags, bytes) } - } else { - process_heap_init_and_alloc(MaybeUninit::uninit(), flags, bytes) + let heap = get_process_heap(); + if core::intrinsics::unlikely(heap.is_null()) { + return ptr::null_mut(); } -} - -// Get a non-null handle to the default heap of the current process. -// SAFETY: `HEAP` must have been successfully initialized. -#[inline] -unsafe fn get_process_heap() -> c::HANDLE { - HEAP.load(Ordering::Acquire) + // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`. + unsafe { HeapAlloc(heap, flags, bytes) } } // Header containing a pointer to the start of an allocated block. @@ -232,9 +187,9 @@ unsafe impl GlobalAlloc for System { } }; - // SAFETY: because `ptr` has been successfully allocated with this allocator, - // `HEAP` must have been successfully initialized. - let heap = unsafe { get_process_heap() }; + // because `ptr` has been successfully allocated with this allocator, + // there must be a valid process heap. + let heap = get_process_heap(); // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`, // `block` is a pointer to the start of an allocated block. @@ -244,9 +199,9 @@ unsafe impl GlobalAlloc for System { #[inline] unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { if layout.align() <= MIN_ALIGN { - // SAFETY: because `ptr` has been successfully allocated with this allocator, - // `HEAP` must have been successfully initialized. - let heap = unsafe { get_process_heap() }; + // because `ptr` has been successfully allocated with this allocator, + // there must be a valid process heap. + let heap = get_process_heap(); // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`, // `ptr` is a pointer to the start of an allocated block.