Any CPU - Prefer 32 bit

Question

What does the Any CPU - Prefer 32 bit option do?

While I am aware that WinRT can not handle exe and can only run Windows Store apps, there are several questions exist

Answer 1

Based solely on the quote you specified, it suggests that it means the following:

• If the CPU supports 32-bit processing, then the final machine code will be 32-bit (ARM or x86, doesn't matter).

• If not, then the machine code will be 64-bit.

In the days of old, AnyCPU meant "I am platform agnostic." This typically meant that you would get 64-bit on 64-bit platforms, and 32-bit otherwise.

However, there are reasons why you may want 32-bit even on a 64-bit CPU: Pointers are half the size, so you use less memory; code is smaller, so more fits into the cache, etc. But, there was no way to force the CLR to use 32-bit, and still retain 64-bit in the cases it was necessary.

Now, with AnyCPU - 32 bit preferred, you can have your cake (64-bit support when necessary) and eat it too (32-bit support when possible)

Note: If I am not mistaken, Itanium would be a platform that only supports 64-bit, not 32-bit code. There may or may not be others.

Disclaimer: I am not an expert, this is just from various blog posts that I've read over the last 6 months or so

Answer 2

Windows RT requires exe files to be signed for it to run. But if you jailbreak your RT then it can run any exe file as long as it is supported on Windows on ARM (.NET or native ARM) apps

More on this option on What AnyCPU Really Means As Of .NET 4.5 and Visual Studio 11