Register Preservation in Inline ASM Blocks

[Walter Bright]

dsimcha wrote:
> What is the rule on who is responsible for saving registers when inserting an
> inline ASM block into the middle of a function?  For example:
> 
> void fun() {
>     auto ptr = somePointer();
>     asm {
>         mov EAX, ptr;
>         lock;
>         inc [EAX];
>     }
> }
> 
> Is this acceptable (will the compiler do what it needs to do to deal with my
> usage of EAX), or do I need to do something more like:
> 
> asm {
>     push EAX;
>     lock;
>     inc [EAX];
>     pop EAX;
> }
> 
> , leaving EAX exactly as I found it?

Unless you use 'naked' asm, the compiler will figure it out for you.