There are a number of unnecessary uses of Unsafe.AsPointer in this repository (e.g.

) - this is a extra dangerous API that can easily be used wrongly (see #99138 as an example that slipped by a number of people). While the current remaining uses seem safe currently at a glance, we might be better off replacing a number of the unnecessary uses with other APIs, and/or adding a comment explaining why it's safe in this case (like in ), and disrecommending their use in the future without a very good reason.

Most of the uses can be broken in to 2 categories:

• Aligning or detecting alignment of a reference (we can introduce helper APIs for this, e.g.

  runtime/src/libraries/System.Private.CoreLib/src/System/Text/Ascii.cs

  Line 144 in eaa6f01

  nuint misalignedElements = ((nuint)Unsafe.AsPointer(ref searchSpace) & (nuint)(Vector256<byte>.Count - 1)) / (nuint)sizeof(T);

  )
• Getting a pointer to something that is known to be pinned (many of these cases could be converted to ref fields instead, using refs/spans directly, or passing by pointer, e.g.

  runtime/src/mono/System.Private.CoreLib/src/System/Reflection/TypeNameParser.Mono.cs

  Line 48 in eaa6f01

  _stackMark = Unsafe.AsPointer(ref stackMark)

  )

The idea was mentioned by @tannergooding on the discord, and one of the suggested solutions was to create an internal API bool IsOpportunisticallyAligned(ref T address, nuint aligment) or similar for the alignment uses.

I am happy to make PRs for these. @tannergooding suggested that I make one for each area separately. Just making this issue to track it and get support for the general idea from people.

/cc @stephentoub @jkotas @tannergooding