title: C address of function parameter?
body: <p>Is it guaranteed safe/portable to use the address of a function parameter on a C89/C99-compliant compiler?</p>
  
  <p>As an example, the AAPCS for 32-bit ARM uses registers r0-r3 for parameter passing if the function parameters meet specific size and alignment requirements. I would assume that using the address of a parameter passed through a register would yield unexpected results, but I ran a test on the ARM compiler I'm using and it appears to relocate these parameters to the stack if the code attempts to reference the addresses of these parameter. While it would appear safe in my particular application, I'm wondering if this is guaranteed across architectures (with an ANSI/ISO-compliant compiler) that can utilize registers directly to pass function parameters.</p>
  
  <p>Do the standards define this behavior?</p>