From 82cbd188b39afec817f26427be5ed481cab97af7 Mon Sep 17 00:00:00 2001
From: Tim Diekmann <tim.diekmann@3dvision.de>
Date: Sat, 8 Aug 2020 08:28:51 +0200
Subject: [PATCH] Let compiler assume, that `Layout::align()` is always a power
 of two

---
 library/core/src/alloc/layout.rs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/library/core/src/alloc/layout.rs b/library/core/src/alloc/layout.rs
index 7129f0f240291..9708bac0fe331 100644
--- a/library/core/src/alloc/layout.rs
+++ b/library/core/src/alloc/layout.rs
@@ -107,7 +107,15 @@ impl Layout {
     #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[inline]
     pub const fn align(&self) -> usize {
-        self.align_.get()
+        let align = self.align_.get();
+        if !align.is_power_of_two() {
+            debug_assert!(false, "alignment is not a power of two");
+            // SAFETY: align is guaranteed to be a power of two
+            unsafe {
+                crate::hint::unreachable_unchecked();
+            }
+        }
+        align
     }
 
     /// Constructs a `Layout` suitable for holding a value of type `T`.