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From: Samuel Hornus <Samuel.Hornus@inria.fr>
In-Reply-To: <CAGmVoG2e6jG3s1-f==UsPq9MKxziS+N8PK2DfqwC8c4zawM9pQ@mail.gmail.com>
Date: Sat, 17 Nov 2012 19:42:58 +0100
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References: <70435661-3754-4815-9EEF-B52F33D29B5F@inria.fr> <CAGmVoG2e6jG3s1-f==UsPq9MKxziS+N8PK2DfqwC8c4zawM9pQ@mail.gmail.com>
To: O Caml <caml-list@inria.fr>
X-Mailer: Apple Mail (2.1283)
Subject: Re: [Caml-list] Segfault in C++ stub with many 'new' allocations


On 17 nov. 2012, at 19:35, Kakadu wrote:

> 2) AFAIR there are functions like register_global_root which prevents GC =
from moving values.

Thank you Kakadu. It is interesting to know that one can use this function =
directly. I knew its existence only through the CAML[x]param* macros=85

Regarding my first question, if it can help, here is the relevant part of m=
y C++ code:
---8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<---
ANNbd_tree * create_bd_tree_flat(ANNcoord * arr, int n, int dim)
{
	// ANNcoord =3D double
	// ANNpoint =3D double*
	// ANNpointArray =3D double**

    ANNbd_tree * ptr;
    std::cerr << "\nCreating flat Bd_tree with " << n << " points of dim " =
<< dim;

    ANNpointArray ptarr =3D new ANNpoint[n];
    for( int i =3D 0; i < n; ++i )
    {
        ptarr[i] =3D arr + dim * i;
    }
    std::cerr << " CHK ";
    ptr =3D new ANNbd_tree(ptarr,n,dim); // Crashes here when 'n' is big
    std::cerr << "done";
    return ptr;
}

extern "C" value ann_create_bd_tree_flat_ba (value ba, value n, value dim)
{
    CAMLparam3(ba,n,dim);
    ANNbd_tree * ptr =3D create_bd_tree_flat((ANNcoord*)Caml_ba_data_val(ba=
), Int_val(n), Int_val(dim));
    CAMLreturn ((value)ptr);
}
---8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<---

The second function is called from OCaml, and the crash happens in the firs=
t function, in the constructor ANNbd_tree() ("CHK" is printed on the termin=
al, "done" is not)
--=20
Sam=