NGEN x86 vs x64 with .NET executables

Question

I have the following question:

My .NET assemblies are compiled in x86 mode. Can I still leverage the performance benefits of NGEN on x64 Windows systems? Will x86 assemblies be compiled into native code on x64?

Answer 1

Assemblies compiled with x86 will run i wow64 on 64-bits systems, but assemblies copiled with AnyCPU will run natively, regardless of NGEN. Assemblies compiled for x86 can load 32-bit assemblies on 64-bit systems and code compiled for AnyCPU will not load 32-bit dlls.

When you use NGEN you will avoid JIT-compiling of the assembly and the assembly will be native x86 code when compiled with x86 also on x64 systems.