[LLVMdev] Broke my tail (call)

[Dan Gohman]

On Feb 23, 2009, at 5:59 AM, Anton Korobeynikov wrote:

>> This is all swinging on my interpretation of first-class structs  
>> though. I am
>> under the impression that they are essentially a set of registers  
>> holding
>> their first-class fields. So you can pass them by value as  
>> arguments to
>> functions with the behaviour of any other first-class type  
>> regardless of
>> where they came from.
> This is not true in general and highly target- and CC- dependent. For
> example, you can ran out of registers and then your struct can be  
> passed
> partly in registers and partly on stack. And depending on the stack
> frame size of the callee you can easily get infinite stack growth.


There is a sense in which it is true -- first-class structs are  
converted
to a set of *virtual* registers holding their first-class fields,  
which may
of course be passed on the stack when physical registers run short,
in exactly the same manner as with lots of scalar arguments.

Dan