The Alpha edition of Visual C++ supports the same command-line options as the x86 edition, with the exception of some code-generation options. These options fall into three groups: processor targeting, calling conventions, and optimization.
The following x86-specific processor targeting options are accepted, but ignored:
| Option | Description |
| /G3 | Optimize for 80386 |
| /G4 | Optimize for 80486 |
| /G5 | Optimize for Pentium |
See the Options for Maximum Speed section for information on switches to target your application for specific Alpha processor families.
The Alpha edition of Visual C++ recognizes only the Alpha calling convention. This cannot be modified, overridden, or disabled.
The following table summarizes support for compiler options on Alpha platforms. If an option is unsupported on your platform, it should be removed from makefiles.
| Option | Description | Alpha |
| /Oa | Assume no aliasing | Supported |
| /Ow | Assume aliasing across function calls | Supported |
| /Og | Enable global optimization | Ignored |
| /Op | Preserve floating-point accuracy | Supported |
| /Op– | Allow loss of low bit(s) of floating-point calculations | Supported |
| /Ot | Specify fast sequences of machine code | Supported |
| /Oy | Omit frame pointer in the program stack | Ignored |
| /Oy– | Generate frame pointer in the program stack | Supported |
| /Gd | Use the _ _cdecl calling convention | Ignored |
| /Gr | Use the _ _fastcall calling convention | Ignored |
| /Gz | Use the _ _stdcall calling convention | Ignored |
| /Gs | Disable stack checking | Supported |
| /Ge | Enable stack checking | Supported |
You can use PROCESSOR_ARCHITECTURE to maintain the same makefile for both platforms, as described in the section Testing the Processor Type in Makefiles. Disable the x86-specific options when the value of this string is not “x86”.