[llvm] [LangRef/DataLayout] Spell out requirements for alignment values (PR #104705)

[Nikita Popov via llvm-commits]

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@@ -3123,6 +3120,9 @@ as follows:
     as :ref:`Non-Integral Pointer Type <nointptrtype>` s.  The ``0``
     address space cannot be specified as non-integral.
 
+Unless explicitly stated otherwise, on every specification that specifies
+an alignment, the value of the alignment must be in the range [1,2^16)
+and must be a power of two times the width of a byte.
----------------
nikic wrote:

```suggestion
and must be a power of two greater than the width of a byte.
```
Would be slightly clearer imho -- but preclude non-power-of-two bytes. Was potentially allowing those in the future the motivation for the chosen wording?

https://github.com/llvm/llvm-project/pull/104705