| // 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)] |
| #![feature(alloc_layout_extra)] |
| #![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))] |
| // 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; |
| |
| /// 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; |
| #[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! |
| } |
| } |
