Register usage in PROCs

[jj2007]

Thanks. Checking a reg and branching if ZERO ..

Code Select Expand


     test   eax, eax
     jz     isZero

or

Code Select Expand


     cmp   eax, 0
     je    isZero

Or is there another better way?

cmp eax, 0 is one byte longer than test eax, eax (but for al, they both have the same size).
Otherwise they are equivalent, also speed-wise.

Note that for readability of code you can use

Code Select Expand

  test eax, eax
  .If Zero?
    nop
  .elseif Sign?
    nop
  .else
    nop
  .endif

Code generated is not a single byte longer, but when sources are getting longer and longer, you will appreciate this syntax.

[CCurl]

..

cmp eax, 0 is one byte longer than test eax, eax (but for al, they both have the same size).
Otherwise they are equivalent, also speed-wise.

Note that for readability of code you can use

Code Select Expand

  test eax, eax
  .If Zero?
    nop
  .elseif Sign?
    nop
  .else
    nop
  .endif

Code generated is not a single byte longer, but when sources are getting longer and longer, you will appreciate this syntax.

Good tip!  :t