Optimize checked_next_power_of_two consumers

library/core/src/num/uint_macros.rs

@@ -3954,7 +3954,20 @@ macro_rules! uint_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         pub const fn checked_next_power_of_two(self) -> Option<Self> {
-            self.one_less_than_next_power_of_two().checked_add(1)
+            let result = self.one_less_than_next_power_of_two().checked_add(1);
+
+            if let Some(result) = result {
+                // SAFETY: `one_less_than_next_power_of_two` returns one less than the
+                // smallest power of two greater than or equal to `self`. Therefore, if
+                // adding one succeeds, the result is a power of two at least as large as
+                // `self`.
+                unsafe {
+                    crate::hint::assert_unchecked(result.is_power_of_two());
+                    crate::hint::assert_unchecked(result >= self);
+                }
+            }
+
+            result
         }
 
         /// Returns the smallest power of two greater than or equal to `n`. If

tests/codegen-llvm/checked-next-power-of-two.rs

@@ -0,0 +1,25 @@
+//@ compile-flags: -Copt-level=3
+
+#![crate_type = "lib"]
+#![no_std]
+
+// CHECK-LABEL: @checked_next_power_of_two_properties
+// CHECK: ret i1 true
+#[no_mangle]
+pub fn checked_next_power_of_two_properties(value: u64) -> bool {
+    value
+        .checked_next_power_of_two()
+        .is_none_or(|result| result.is_power_of_two() && result >= value)
+}
+
+// CHECK-LABEL: @modulo_checked_next_power_of_two
+// CHECK-NOT: udiv
+// CHECK-NOT: urem
+// CHECK: and i64
+// CHECK-NOT: udiv
+// CHECK-NOT: urem
+// CHECK: ret
+#[no_mangle]
+pub fn modulo_checked_next_power_of_two(value: u64, dividend: u64) -> Option<u64> {
+    value.checked_next_power_of_two().map(|divisor| dividend % divisor)
+}