--- /dev/null
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+#![no_std]
+#![allow(unused_attributes)]
+#![unstable(feature = "alloc_system",
+ reason = "this library is unlikely to be stabilized in its current \
+ form or name",
+ issue = "32838")]
+#![feature(allocator_api)]
+#![feature(core_intrinsics)]
+#![feature(nll)]
+#![feature(staged_api)]
+#![feature(rustc_attrs)]
+#![cfg_attr(
+ all(target_arch = "wasm32", not(target_os = "emscripten")),
+ feature(integer_atomics, stdsimd)
+)]
+#![cfg_attr(any(unix, target_os = "cloudabi", target_os = "redox"), feature(libc))]
+#![rustc_alloc_kind = "lib"]
+// The minimum alignment guaranteed by the architecture. This value is used to
+// add fast paths for low alignment values.
+#[cfg(all(any(target_arch = "x86",
+ target_arch = "arm",
+ target_arch = "mips",
+ target_arch = "powerpc",
+ target_arch = "powerpc64",
+ target_arch = "asmjs",
+ target_arch = "wasm32")))]
+#[allow(dead_code)]
+const MIN_ALIGN: usize = 8;
+#[cfg(all(any(target_arch = "x86_64",
+ target_arch = "aarch64",
+ target_arch = "mips64",
+ target_arch = "s390x",
+ target_arch = "sparc64")))]
+#[allow(dead_code)]
+const MIN_ALIGN: usize = 16;
+use core::alloc::{Alloc, GlobalAlloc, AllocErr, Layout};
+use core::ptr::NonNull;
+/// The default memory allocator provided by the operating system.
+///
+/// This is based on `malloc` on Unix platforms and `HeapAlloc` on Windows,
+/// plus related functions.
+///
+/// This type can be used in a `static` item
+/// with the `#[global_allocator]` attribute
+/// to force the global allocator to be the system’s one.
+/// (The default is jemalloc for executables, on some platforms.)
+///
+/// ```rust
+/// use std::alloc::System;
+///
+/// #[global_allocator]
+/// static A: System = System;
+///
+/// fn main() {
+/// let a = Box::new(4); // Allocates from the system allocator.
+/// println!("{}", a);
+/// }
+/// ```
+///
+/// It can also be used directly to allocate memory
+/// independently of the standard library’s global allocator.
+#[stable(feature = "alloc_system_type", since = "1.28.0")]
+pub struct System;
+#[unstable(feature = "allocator_api", issue = "32838")]
+unsafe impl Alloc for System {
+ #[inline]
+ unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
+ NonNull::new(GlobalAlloc::alloc(self, layout)).ok_or(AllocErr)
+ }
+ #[inline]
+ unsafe fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
+ NonNull::new(GlobalAlloc::alloc_zeroed(self, layout)).ok_or(AllocErr)
+ }
+ #[inline]
+ unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+ GlobalAlloc::dealloc(self, ptr.as_ptr(), layout)
+ }
+ #[inline]
+ unsafe fn realloc(&mut self,
+ ptr: NonNull<u8>,
+ layout: Layout,
+ new_size: usize) -> Result<NonNull<u8>, AllocErr> {
+ NonNull::new(GlobalAlloc::realloc(self, ptr.as_ptr(), layout, new_size)).ok_or(AllocErr)
+ }
+}
+#[cfg(any(windows, unix, target_os = "cloudabi", target_os = "redox"))]
+mod realloc_fallback {
+ use core::alloc::{GlobalAlloc, Layout};
+ use core::cmp;
+ use core::ptr;
+ impl super::System {
+ pub(crate) unsafe fn realloc_fallback(&self, ptr: *mut u8, old_layout: Layout,
+ new_size: usize) -> *mut u8 {
+ // Docs for GlobalAlloc::realloc require this to be valid:
+ let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());
+ let new_ptr = GlobalAlloc::alloc(self, new_layout);
+ if !new_ptr.is_null() {
+ let size = cmp::min(old_layout.size(), new_size);
+ ptr::copy_nonoverlapping(ptr, new_ptr, size);
+ GlobalAlloc::dealloc(self, ptr, old_layout);
+ }
+ new_ptr
+ }
+ }
+}
+#[cfg(any(unix, target_os = "cloudabi", target_os = "redox"))]
+mod platform {
+ extern crate libc;
+ use core::ptr;
+ use MIN_ALIGN;
+ use System;
+ use core::alloc::{GlobalAlloc, Layout};
+ #[stable(feature = "alloc_system_type", since = "1.28.0")]
+ unsafe impl GlobalAlloc for System {
+ #[inline]
+ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+ 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 {
+ if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+ libc::calloc(layout.size(), 1) as *mut u8
+ } else {
+ let ptr = self.alloc(layout.clone());
+ 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 {
+ self.realloc_fallback(ptr, layout, new_size)
+ }
+ }
+ }
+ #[cfg(any(target_os = "android",
+ target_os = "hermit",
+ target_os = "redox",
+ target_os = "solaris"))]
+ #[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
+ }
+ #[cfg(not(any(target_os = "android",
+ target_os = "hermit",
+ target_os = "redox",
+ target_os = "solaris")))]
+ #[inline]
+ unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
+ let mut out = ptr::null_mut();
+ let ret = libc::posix_memalign(&mut out, layout.align(), layout.size());
+ if ret != 0 {
+ ptr::null_mut()
+ } else {
+ out as *mut u8
+ }
+ }
+}
+#[cfg(windows)]
+#[allow(nonstandard_style)]
+mod platform {
+ use MIN_ALIGN;
+ use System;
+ use core::alloc::{GlobalAlloc, Layout};
+ type LPVOID = *mut u8;
+ type HANDLE = LPVOID;
+ type SIZE_T = usize;
+ type DWORD = u32;
+ type BOOL = i32;
+ extern "system" {
+ fn GetProcessHeap() -> HANDLE;
+ fn HeapAlloc(hHeap: HANDLE, dwFlags: DWORD, dwBytes: SIZE_T) -> LPVOID;
+ fn HeapReAlloc(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID, dwBytes: SIZE_T) -> LPVOID;
+ fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID) -> BOOL;
+ fn GetLastError() -> DWORD;
+ }
+ #[repr(C)]
+ struct Header(*mut u8);
+ const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
+ unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
+ &mut *(ptr as *mut Header).offset(-1)
+ }
+ unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
+ let aligned = ptr.add(align - (ptr as usize & (align - 1)));
+ *get_header(aligned) = Header(ptr);
+ aligned
+ }
+ #[inline]
+ unsafe fn allocate_with_flags(layout: Layout, flags: DWORD) -> *mut u8 {
+ let ptr = if layout.align() <= MIN_ALIGN {
+ HeapAlloc(GetProcessHeap(), flags, layout.size())
+ } else {
+ let size = layout.size() + layout.align();
+ let ptr = HeapAlloc(GetProcessHeap(), flags, size);
+ if ptr.is_null() {
+ ptr
+ } else {
+ align_ptr(ptr, layout.align())
+ }
+ };
+ ptr as *mut u8
+ }
+ #[stable(feature = "alloc_system_type", since = "1.28.0")]
+ unsafe impl GlobalAlloc for System {
+ #[inline]
+ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+ allocate_with_flags(layout, 0)
+ }
+ #[inline]
+ unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+ allocate_with_flags(layout, HEAP_ZERO_MEMORY)
+ }
+ #[inline]
+ unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+ if layout.align() <= MIN_ALIGN {
+ let err = HeapFree(GetProcessHeap(), 0, ptr as LPVOID);
+ debug_assert!(err != 0, "Failed to free heap memory: {}",
+ GetLastError());
+ } else {
+ let header = get_header(ptr);
+ let err = HeapFree(GetProcessHeap(), 0, header.0 as LPVOID);
+ debug_assert!(err != 0, "Failed to free heap memory: {}",
+ GetLastError());
+ }
+ }
+ #[inline]
+ unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+ if layout.align() <= MIN_ALIGN {
+ HeapReAlloc(GetProcessHeap(), 0, ptr as LPVOID, new_size) as *mut u8
+ } else {
+ self.realloc_fallback(ptr, layout, new_size)
+ }
+ }
+ }
+}
+// This is an implementation of a global allocator on the wasm32 platform when
+// emscripten is not in use. In that situation there's no actual runtime for us
+// to lean on for allocation, so instead we provide our own!
+//
+// The wasm32 instruction set has two instructions for getting the current
+// amount of memory and growing the amount of memory. These instructions are the
+// foundation on which we're able to build an allocator, so we do so! Note that
+// the instructions are also pretty "global" and this is the "global" allocator
+// after all!
+//
+// The current allocator here is the `dlmalloc` crate which we've got included
+// in the rust-lang/rust repository as a submodule. The crate is a port of
+// dlmalloc.c from C to Rust and is basically just so we can have "pure Rust"
+// for now which is currently technically required (can't link with C yet).
+//
+// The crate itself provides a global allocator which on wasm has no
+// synchronization as there are no threads!
+#[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))]
+mod platform {
+ extern crate dlmalloc;
+ use core::alloc::{GlobalAlloc, Layout};
+ use System;
+ static mut DLMALLOC: dlmalloc::Dlmalloc = dlmalloc::DLMALLOC_INIT;
+ #[stable(feature = "alloc_system_type", since = "1.28.0")]
+ unsafe impl GlobalAlloc for System {
+ #[inline]
+ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+ let _lock = lock::lock();
+ DLMALLOC.malloc(layout.size(), layout.align())
+ }
+ #[inline]
+ unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+ let _lock = lock::lock();
+ DLMALLOC.calloc(layout.size(), layout.align())
+ }
+ #[inline]
+ unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+ let _lock = lock::lock();
+ DLMALLOC.free(ptr, layout.size(), layout.align())
+ }
+ #[inline]
+ unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+ let _lock = lock::lock();
+ DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size)
+ }
+ }
+ #[cfg(target_feature = "atomics")]
+ mod lock {
+ use core::arch::wasm32;
+ use core::sync::atomic::{AtomicI32, Ordering::SeqCst};
+ static LOCKED: AtomicI32 = AtomicI32::new(0);
+ pub struct DropLock;
+ pub fn lock() -> DropLock {
+ loop {
+ if LOCKED.swap(1, SeqCst) == 0 {
+ return DropLock
+ }
+ unsafe {
+ let r = wasm32::atomic::wait_i32(
+ &LOCKED as *const AtomicI32 as *mut i32,
+ 1, // expected value
+ -1, // timeout
+ );
+ debug_assert!(r == 0 || r == 1);
+ }
+ }
+ }
+ impl Drop for DropLock {
+ fn drop(&mut self) {
+ let r = LOCKED.swap(0, SeqCst);
+ debug_assert_eq!(r, 1);
+ unsafe {
+ wasm32::atomic::wake(
+ &LOCKED as *const AtomicI32 as *mut i32,
+ 1, // only one thread
+ );
+ }
+ }
+ }
+ }
+ #[cfg(not(target_feature = "atomics"))]
+ mod lock {
+ #[inline]
+ pub fn lock() {} // no atomics, no threads, that's easy!
+ }
+}
projects / rust.git / commitdiff