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Diffstat (limited to 'compiler/rustc_codegen_gcc/example/alloc_system.rs')
| -rw-r--r-- | compiler/rustc_codegen_gcc/example/alloc_system.rs | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_gcc/example/alloc_system.rs b/compiler/rustc_codegen_gcc/example/alloc_system.rs new file mode 100644 index 00000000000..945d34063a6 --- /dev/null +++ b/compiler/rustc_codegen_gcc/example/alloc_system.rs @@ -0,0 +1,221 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// SPDX-FileCopyrightText: The Rust Project Developers (see https://thanks.rust-lang.org) + +#![no_std] +#![feature(allocator_api, rustc_private)] + +// The minimum alignment guaranteed by the architecture. This value is used to +// add fast paths for low alignment values. +#[cfg(any(target_arch = "x86", + target_arch = "arm", + target_arch = "m68k", + target_arch = "mips", + target_arch = "mips32r6", + target_arch = "powerpc", + target_arch = "csky", + target_arch = "powerpc64"))] +const MIN_ALIGN: usize = 8; +#[cfg(any(target_arch = "x86_64", + target_arch = "aarch64", + target_arch = "loongarch64", + target_arch = "mips64", + target_arch = "mips64r6", + target_arch = "s390x", + target_arch = "sparc64"))] +const MIN_ALIGN: usize = 16; + +pub struct System; +#[cfg(any(windows, unix, 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 = "redox"))] +mod platform { + mod libc { + use core::ffi::{c_void, c_int}; + + #[link(name = "c")] + extern "C" { + pub fn malloc(size: usize) -> *mut c_void; + pub fn realloc(ptr: *mut c_void, size: usize) -> *mut c_void; + pub fn calloc(nmemb: usize, size: usize) -> *mut c_void; + pub fn free(ptr: *mut u8); + pub fn posix_memalign(memptr: *mut *mut c_void, alignment: usize, size: usize) -> c_int; + } + } + use core::ptr; + use MIN_ALIGN; + use System; + use core::alloc::{GlobalAlloc, Layout}; + 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 _) + } + #[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 _, 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).sub(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 + } + 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) + } + } + } +} |