Re: [libunwind] alloca()

[Johan Walles]

David Mosberger wrote:
> > > > > > On Wed, 10 Dec 2003 17:34:24 +0100, Johan Walles <address@hidden> said:
>
>   Johan> We have a (dynamically generated) function that uses a
>   Johan> dynamic amount of user stack.
>
>   Johan> do we just say that r42 contains the unmodified
>   Johan> usp (see below)?
>
> It's the latter.  That is, for this code:
>
>   Johan> 0x20000000627381d0: [MII]       alloc r40=ar.pfs,24,16,0
>   Johan> 0x20000000627381d1:             mov r41=b0
>   Johan> 0x20000000627381d2:             add r42=r12,r0
>
> you'd use something along the lines of:
>
>         _U_dyn_op_save_reg (op, _U_QP_TRUE, 2, UNW_REG_SP, UNW_REG_GR + 42);

So, this would mean that if I have stopped the program in a place where the 
stack pointer has been dynamically modified, I won't get a correct stack pointer 
if I ask libunwind about it?

Since the listed function is the only one of its kind this is hardly something 
that will keep me awake at night, I just want to know if I've understood the 
problem (and its solution) correctly.

  Cheers //Johan