llvm dev - Jul 2011 - [LLVMdev] Problem with stack arguments

Hallo!

I use a custom calling convention in which the first 4 arguments are 
promoted to registers and the rest to the stack, and the callee is 
responsible for popping the stack arguments.

So when calling a function with 5 arguments  i get this code:

     movq    ARG_5, (%rsp)
     callq    fun_foo_1
.Ltmp4:
     subq    $8, %rsp

I use a garbage collector with postcall safe points (.Ltmp4 is such) 
which needs to know the frame size, for
each safe point. The problem is that at .Ltmp4  the frame size is 
actually different from what getFrameSize() would return.

So is there a way to force generation of code which pushes arguments ?

For example :

pushq ARG_5
callq fun_foo_1
     .Ltmp4

Thnks,
Chris Stavrakakis
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On 07/29/2011 02:47 PM, Chris Stavrakakis wrote:
> Hallo!
>
> I use a custom calling convention in which the first 4 arguments are
> promoted to registers and the rest to the stack, and the callee is
> responsible for popping the stack arguments.
>
> So when calling a function with 5 arguments  i get this code:
>
>     movq    ARG_5, (%rsp)
>     callq    fun_foo_1
> .Ltmp4:
>     subq    $8, %rsp
>
> I use a garbage collector with postcall safe points (.Ltmp4 is such)
> which needs to know the frame size, for
> each safe point. The problem is that at .Ltmp4  the frame size is
> actually different from what getFrameSize() would return.
>
> So is there a way to force generation of code which pushes arguments ?
>
> For example :
>
> pushq ARG_5
> callq fun_foo_1
>     .Ltmp4
>
> Thnks,
> Chris Stavrakakis
>   
Hi all,

Let me elaborate more on what Chris wanted to say because this is my
problem too! :-)
Is there a way to force llvm not to reserve argument space for call
frames? The problem is that we use a GC and when it is triggered it
messes up the caller's frame (in the case that the callee has more than
4 arguments), as Chris said. If there is any idea that might help we
would be grateful!

Thanks,
Yiannis