| use crate::alloc::{GlobalAlloc, Layout, System}; |
| use crate::ptr; |
| use crate::sys::common::alloc::{realloc_fallback, MIN_ALIGN}; |
| |
| #[stable(feature = "alloc_system_type", since = "1.28.0")] |
| unsafe impl GlobalAlloc for System { |
| #[inline] |
| unsafe fn alloc(&self, layout: Layout) -> *mut u8 { |
| // jemalloc provides alignment less than MIN_ALIGN for small allocations. |
| // So only rely on MIN_ALIGN if size >= align. |
| // Also see <https://github.com/rust-lang/rust/issues/45955> and |
| // <https://github.com/rust-lang/rust/issues/62251#issuecomment-507580914>. |
| if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { |
| libc::malloc(layout.size()) as *mut u8 |
| } else { |
| #[cfg(target_os = "macos")] |
| { |
| if layout.align() > (1 << 31) { |
| return ptr::null_mut(); |
| } |
| } |
| aligned_malloc(&layout) |
| } |
| } |
| |
| #[inline] |
| unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { |
| // See the comment above in `alloc` for why this check looks the way it does. |
| if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { |
| libc::calloc(layout.size(), 1) as *mut u8 |
| } else { |
| let ptr = self.alloc(layout); |
| if !ptr.is_null() { |
| ptr::write_bytes(ptr, 0, layout.size()); |
| } |
| ptr |
| } |
| } |
| |
| #[inline] |
| unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) { |
| libc::free(ptr as *mut libc::c_void) |
| } |
| |
| #[inline] |
| unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { |
| if layout.align() <= MIN_ALIGN && layout.align() <= new_size { |
| libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8 |
| } else { |
| realloc_fallback(self, ptr, layout, new_size) |
| } |
| } |
| } |
| |
| cfg_if::cfg_if! { |
| if #[cfg(any( |
| target_os = "android", |
| target_os = "illumos", |
| target_os = "redox", |
| target_os = "solaris", |
| target_os = "espidf", |
| target_os = "horizon" |
| ))] { |
| #[inline] |
| unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 { |
| // On android we currently target API level 9 which unfortunately |
| // doesn't have the `posix_memalign` API used below. Instead we use |
| // `memalign`, but this unfortunately has the property on some systems |
| // where the memory returned cannot be deallocated by `free`! |
| // |
| // Upon closer inspection, however, this appears to work just fine with |
| // Android, so for this platform we should be fine to call `memalign` |
| // (which is present in API level 9). Some helpful references could |
| // possibly be chromium using memalign [1], attempts at documenting that |
| // memalign + free is ok [2] [3], or the current source of chromium |
| // which still uses memalign on android [4]. |
| // |
| // [1]: https://codereview.chromium.org/10796020/ |
| // [2]: https://code.google.com/p/android/issues/detail?id=35391 |
| // [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579 |
| // [4]: https://chromium.googlesource.com/chromium/src/base/+/master/ |
| // /memory/aligned_memory.cc |
| libc::memalign(layout.align(), layout.size()) as *mut u8 |
| } |
| } else if #[cfg(target_os = "wasi")] { |
| #[inline] |
| unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 { |
| libc::aligned_alloc(layout.align(), layout.size()) as *mut u8 |
| } |
| } else { |
| #[inline] |
| unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 { |
| let mut out = ptr::null_mut(); |
| // posix_memalign requires that the alignment be a multiple of `sizeof(void*)`. |
| // Since these are all powers of 2, we can just use max. |
| let align = layout.align().max(crate::mem::size_of::<usize>()); |
| let ret = libc::posix_memalign(&mut out, align, layout.size()); |
| if ret != 0 { ptr::null_mut() } else { out as *mut u8 } |
| } |
| } |
| } |
