[LLVMdev] Problem with stack arguments

Yiannis Tsiouris yiannis.tsiouris at gmail.com
Sun Sep 4 02:44:40 PDT 2011

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!


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