Rollup merge of #125003 - RalfJung:aligned_alloc, r=cuviper · rust-lang/rust@c5b17ec (original) (raw)
`@@ -87,21 +87,18 @@ cfg_if::cfg_if! {
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`// /memory/aligned_memory.cc
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` libc::memalign(layout.align(), layout.size()) as *mut u8
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`}
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``
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} else if #[cfg(target_os = "wasi")] {
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``
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#[inline]
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``
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unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
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``
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// C11 aligned_alloc requires that the size be a multiple of the alignment.
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``
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// Layout already checks that the size rounded up doesn't overflow isize::MAX.
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``
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let align = layout.align();
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``
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let size = layout.size().next_multiple_of(align);
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``
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libc::aligned_alloc(align, 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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``
`` -
// posix_memalign requires that the alignment be a multiple of sizeof(void*).
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// Since these are all powers of 2, we can just use max.
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// We prefer posix_memalign over aligned_malloc since with aligned_malloc,
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// implementations are making almost arbitrary choices for which alignments are
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// "supported", making it hard to use. For instance, some implementations require the
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// size to be a multiple of the alignment (wasi emmalloc), while others require the
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// alignment to be at least the pointer size (Illumos, macOS) -- which may or may not be
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// standards-compliant, but that does not help us.
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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::());
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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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