84 lines
2.6 KiB
Rust
84 lines
2.6 KiB
Rust
#![feature(allocator_api)]
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use std::ptr::NonNull;
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use std::alloc::{Global, Alloc, Layout, System};
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use std::slice;
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fn check_alloc<T: Alloc>(mut allocator: T) { unsafe {
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let layout = Layout::from_size_align(20, 4).unwrap();
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let a = allocator.alloc(layout).unwrap();
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allocator.dealloc(a, layout);
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let p1 = allocator.alloc_zeroed(layout).unwrap();
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let p2 = allocator.realloc(p1, Layout::from_size_align(20, 4).unwrap(), 40).unwrap();
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let slice = slice::from_raw_parts(p2.as_ptr(), 20);
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assert_eq!(&slice, &[0_u8; 20]);
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// old size == new size
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let p3 = allocator.realloc(p2, Layout::from_size_align(40, 4).unwrap(), 40).unwrap();
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let slice = slice::from_raw_parts(p3.as_ptr(), 20);
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assert_eq!(&slice, &[0_u8; 20]);
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// old size > new size
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let p4 = allocator.realloc(p3, Layout::from_size_align(40, 4).unwrap(), 10).unwrap();
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let slice = slice::from_raw_parts(p4.as_ptr(), 10);
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assert_eq!(&slice, &[0_u8; 10]);
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allocator.dealloc(p4, Layout::from_size_align(10, 4).unwrap());
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} }
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fn check_overalign_requests<T: Alloc>(mut allocator: T) {
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let size = 8;
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// Greater than `size`.
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let align = 16;
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// Miri is deterministic; no need to try many times.
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let iterations = 1;
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unsafe {
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let pointers: Vec<_> = (0..iterations).map(|_| {
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allocator.alloc(Layout::from_size_align(size, align).unwrap()).unwrap()
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}).collect();
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for &ptr in &pointers {
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assert_eq!((ptr.as_ptr() as usize) % align, 0,
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"Got a pointer less aligned than requested")
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}
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// Clean up.
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for &ptr in &pointers {
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allocator.dealloc(ptr, Layout::from_size_align(size, align).unwrap())
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}
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}
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}
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fn global_to_box() {
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type T = [i32; 4];
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let l = Layout::new::<T>();
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// allocate manually with global allocator, then turn into Box and free there
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unsafe {
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let ptr = Global.alloc(l).unwrap().as_ptr() as *mut T;
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let b = Box::from_raw(ptr);
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drop(b);
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}
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}
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fn box_to_global() {
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type T = [i32; 4];
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let l = Layout::new::<T>();
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// allocate with the Box, then deallocate manually with global allocator
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unsafe {
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let b = Box::new(T::default());
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let ptr = Box::into_raw(b);
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Global.dealloc(NonNull::new(ptr as *mut u8).unwrap(), l);
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}
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}
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fn main() {
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check_alloc(System);
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check_alloc(Global);
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#[cfg(not(target_os = "windows"))] // TODO: Inspects allocation base address on Windows; needs intptrcast model
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check_overalign_requests(System);
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check_overalign_requests(Global);
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global_to_box();
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box_to_global();
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}
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