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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 }
 }
 }
}