use posix_memalign on all Unix targets

Author: RalfJung

library/std/src/sys/pal/unix/alloc.rs

@@ -58,33 +58,17 @@ unsafe impl GlobalAlloc for System {
     }
 }
 
-cfg_if::cfg_if! {
-    // We use posix_memalign wherever possible, but not all targets have that function.
-    if #[cfg(any(
-        target_os = "redox",
-        target_os = "espidf",
-        target_os = "horizon",
-        target_os = "vita",
-    ))] {
-        #[inline]
-        unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
-            libc::memalign(layout.align(), layout.size()) as *mut u8
-        }
-    } else {
-        #[inline]
-        unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
-            let mut out = ptr::null_mut();
-            // We prefer posix_memalign over aligned_malloc since with aligned_malloc,
-            // implementations are making almost arbitrary choices for which alignments are
-            // "supported", making it hard to use. For instance, some implementations require the
-            // size to be a multiple of the alignment (wasi emmalloc), while others require the
-            // alignment to be at least the pointer size (Illumos, macOS) -- which may or may not be
-            // standards-compliant, but that does not help us.
-            // posix_memalign only has one, clear requirement: that the alignment be a multiple of
-            // `sizeof(void*)`. Since these are all powers of 2, we can just use max.
-            let align = layout.align().max(crate::mem::size_of::<usize>());
-            let ret = libc::posix_memalign(&mut out, align, layout.size());
-            if ret != 0 { ptr::null_mut() } else { out as *mut u8 }
-        }
-    }
+unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
+    let mut out = ptr::null_mut();
+    // We prefer posix_memalign over aligned_malloc since it is more widely available, and since
+    // with aligned_malloc, implementations are making almost arbitrary choices for which alignments
+    // are "supported", making it hard to use. For instance, some implementations require the size
+    // to be a multiple of the alignment (wasi emmalloc), while others require the alignment to be
+    // at least the pointer size (Illumos, macOS) -- which may or may not be standards-compliant,
+    // but that does not help us.
+    // posix_memalign only has one, clear requirement: that the alignment be a multiple of
+    // `sizeof(void*)`. Since these are all powers of 2, we can just use max.
+    let align = layout.align().max(crate::mem::size_of::<usize>());
+    let ret = libc::posix_memalign(&mut out, align, layout.size());
+    if ret != 0 { ptr::null_mut() } else { out as *mut u8 }
 }