rusticl: align memory utilities with std

Rename `is_alligned()` util to match std naming and move it alongside
similar utilities which copy upstream functionality and annotate those
utilities with their first stable version where applicable.

Replace use of `mesa_rust_util::offset_of!()` in one case where nested
field support is not needed.

v2: revert removal of `offset_of!()` for nested field support

Reviewed-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: @LingMan
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34167>

src/gallium/frontends/rusticl/api/memory.rs

@@ -656,7 +656,7 @@ fn validate_buffer(
                                 let addr_alignment = dev.image_base_address_alignment();
                                 if addr_alignment == 0 {
                                     return Err(CL_INVALID_OPERATION);
-                                } else if !is_alligned(host_ptr, addr_alignment as usize) {
+                                } else if !is_aligned_to(host_ptr, addr_alignment as usize) {
                                     return Err(err);
                                 }
                             }

src/gallium/frontends/rusticl/api/util.rs

@@ -491,10 +491,6 @@ pub fn checked_compare(a: usize, o: cmp::Ordering, b: u64) -> bool {
     }
 }
 
-pub fn is_alligned<T>(ptr: *const T, alignment: usize) -> bool {
-    ptr as usize & (alignment - 1) == 0
-}
-
 pub fn bit_check<A: BitAnd<Output = A> + PartialEq + Default, B: Into<A>>(a: A, b: B) -> bool {
     a & b.into() != A::default()
 }

src/gallium/frontends/rusticl/mesa/compiler/nir.rs

@@ -1,10 +1,10 @@
 use mesa_rust_gen::*;
 use mesa_rust_util::bitset;
-use mesa_rust_util::offset_of;
 
 use std::convert::TryInto;
 use std::ffi::CStr;
 use std::marker::PhantomData;
+use std::mem::offset_of;
 use std::ops::Not;
 use std::ptr;
 use std::ptr::NonNull;

src/gallium/frontends/rusticl/util/ptr.rs

@@ -95,6 +95,8 @@ impl<T> CheckedPtr<T> for *mut T {
     }
 }
 
+// While std::mem::offset_of!() is stable from 1.77.0, support for nested fields
+// (required in some rusticl cases) wasn't stabilized until 1.82.0.
 // from https://internals.rust-lang.org/t/discussion-on-offset-of/7440/2
 #[macro_export]
 macro_rules! offset_of {
@@ -115,7 +117,7 @@ macro_rules! offset_of {
     }};
 }
 
-// Adapted from libstd since std::ptr::is_aligned is still unstable
+// Adapted from libstd since std::ptr::is_aligned isn't stable until 1.79.0
 // See https://github.com/rust-lang/rust/issues/96284
 #[must_use]
 #[inline]
@@ -123,11 +125,18 @@ pub fn is_aligned<T>(ptr: *const T) -> bool
 where
     T: Sized,
 {
-    let align = mem::align_of::<T>();
+    is_aligned_to(ptr, mem::align_of::<T>())
+}
+
+// Adapted from libstd since std::ptr::is_aligned_to is still unstable
+// See https://github.com/rust-lang/rust/issues/96284
+#[must_use]
+#[inline]
+pub fn is_aligned_to<T>(ptr: *const T, align: usize) -> bool {
     addr(ptr) & (align - 1) == 0
 }
 
-// Adapted from libstd since std::ptr::addr is still unstable
+// Adapted from libstd since std::ptr::addr isn't stable until 1.84.0
 // See https://github.com/rust-lang/rust/issues/95228
 #[must_use]
 #[inline(always)]