dba6b74dd8
Also fix one instance of unsafe_op_in_unsafe_fn that's specific to horizon + vita - most others should be common with other code.
89 lines
3.7 KiB
Rust
89 lines
3.7 KiB
Rust
use crate::alloc::{GlobalAlloc, Layout, System};
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use crate::ptr;
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use crate::sys::common::alloc::{realloc_fallback, MIN_ALIGN};
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#[stable(feature = "alloc_system_type", since = "1.28.0")]
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unsafe impl GlobalAlloc for System {
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#[inline]
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unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
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// jemalloc provides alignment less than MIN_ALIGN for small allocations.
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// So only rely on MIN_ALIGN if size >= align.
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// Also see <https://github.com/rust-lang/rust/issues/45955> and
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// <https://github.com/rust-lang/rust/issues/62251#issuecomment-507580914>.
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if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
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libc::malloc(layout.size()) as *mut u8
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} else {
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// `posix_memalign` returns a non-aligned value if supplied a very
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// large alignment on older versions of Apple's platforms (unknown
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// exactly which version range, but the issue is definitely
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// present in macOS 10.14 and iOS 13.3).
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//
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// <https://github.com/rust-lang/rust/issues/30170>
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#[cfg(target_vendor = "apple")]
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{
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if layout.align() > (1 << 31) {
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return ptr::null_mut();
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}
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}
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aligned_malloc(&layout)
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}
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}
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#[inline]
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unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
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// See the comment above in `alloc` for why this check looks the way it does.
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if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
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libc::calloc(layout.size(), 1) as *mut u8
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} else {
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let ptr = self.alloc(layout);
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if !ptr.is_null() {
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ptr::write_bytes(ptr, 0, layout.size());
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}
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ptr
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}
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}
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#[inline]
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unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
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libc::free(ptr as *mut libc::c_void)
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}
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#[inline]
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unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
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if layout.align() <= MIN_ALIGN && layout.align() <= new_size {
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libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
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} else {
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realloc_fallback(self, ptr, layout, new_size)
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}
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}
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}
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cfg_if::cfg_if! {
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// We use posix_memalign wherever possible, but some targets have very incomplete POSIX coverage
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// so we need a fallback for those.
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if #[cfg(any(
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target_os = "horizon",
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target_os = "vita",
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))] {
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#[inline]
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unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
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unsafe { libc::memalign(layout.align(), layout.size()) as *mut u8 }
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}
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} else {
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#[inline]
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unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
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let mut out = ptr::null_mut();
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// We prefer posix_memalign over aligned_alloc since it is more widely available, and
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// since with aligned_alloc, implementations are making almost arbitrary choices for
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// which alignments are "supported", making it hard to use. For instance, some
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// implementations require the size to be a multiple of the alignment (wasi emmalloc),
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// while others require the alignment to be at least the pointer size (Illumos, macOS).
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// posix_memalign only has one, clear requirement: that the alignment be a multiple of
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// `sizeof(void*)`. Since these are all powers of 2, we can just use max.
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let align = layout.align().max(crate::mem::size_of::<usize>());
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let ret = libc::posix_memalign(&mut out, align, layout.size());
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if ret != 0 { ptr::null_mut() } else { out as *mut u8 }
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}
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}
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}
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