Is it possible to use 64-bit instruction in a 32-bit application on intel/64-bit win7

Question

My environment is 64-bit win7, VC2010.

Of course, the intel inside is 64-bit CPU.

Can I use the 64-bit instruction/native machine word(64-bit) in a 32-bit ap

Answer 1

If your application uses the 32-bit instruction set, then no, you cannot elect to use 64-bit instructions "sometimes" within the same application. There are some options, however:

• Use SIMD instructions, such as SSE, AVX, etc. This is documented here: http://msdn.microsoft.com/en-us/library/t467de55(v=vs.90).aspx
• Port your 32-bit code to 64-bit. Maybe it's not so hard?
• Split your program in two: a 32-bit process with your legacy code, and a 64-bit process with new code. You could map memory between them, and one could launch the other, so it's a bit like a multithreaded program then. Whether it would perform well depends a lot on details we don't know at this time.