[ODE] stack requirements

[David McClurg]

In my simulation I enter dInternalStepIsland_x2() with nb=25 and this routine is taking a ton of stack space to where i get a stack overflow.  I didn't think 25 bodies was too bad.  Anyone have ideas for me?  I'm running on an embedded system and I can't just keep increasing memory requirements.

here are the alloca calls for step.cpp

$ grep -ni alloca step.cpp
39:#define ALLOCA dALLOCA16
290:  dxJoint **joint = (dxJoint**) ALLOCA (nj * sizeof(dxJoint*));
297:  dReal *I = (dReal*) ALLOCA (3*nb*4 * sizeof(dReal));
298:  dReal *invI = (dReal*) ALLOCA (3*nb*4 * sizeof(dReal));
332:  dxJoint::Info1 *info = (dxJoint::Info1*) ALLOCA (nj*sizeof(dxJoint::Info1)
);
333:  int *ofs = (int*) ALLOCA (nj*sizeof(int));
368:  dReal *invM = (dReal*) ALLOCA (n6*nskip*sizeof(dReal));
382:  dReal *fe = (dReal*) ALLOCA (n6 * sizeof(dReal));
383:  dReal *v = (dReal*) ALLOCA (n6 * sizeof(dReal));
394:  dReal *vnew = (dReal*) ALLOCA (n6 * sizeof(dReal));
402:    dReal *c = (dReal*) ALLOCA (m*sizeof(dReal));
403:    dReal *cfm = (dReal*) ALLOCA (m*sizeof(dReal));
404:    dReal *lo = (dReal*) ALLOCA (m*sizeof(dReal));
405:    dReal *hi = (dReal*) ALLOCA (m*sizeof(dReal));
406:    int *findex = (int*) alloca (m*sizeof(int));
418:    dReal *J = (dReal*) ALLOCA (m*nskip*sizeof(dReal));
451:    dReal *JinvM = (dReal*) ALLOCA (m*nskip*sizeof(dReal));
455:    dReal *A = (dReal*) ALLOCA (m*mskip*sizeof(dReal));
470:    dReal *tmp1 = (dReal*) ALLOCA (n6 * sizeof(dReal));
474:    dReal *rhs = (dReal*) ALLOCA (m * sizeof(dReal));
489:    dReal *lambda = (dReal*) ALLOCA (m * sizeof(dReal));
490:    dReal *residual = (dReal*) ALLOCA (m * sizeof(dReal));
499://    dReal *L = (dReal*) ALLOCA (m*mskip*sizeof(dReal));
507://    dReal *lambda = (dReal*) ALLOCA (m * sizeof(dReal));
601:  dxJoint **joint = (dxJoint**) ALLOCA (nj * sizeof(dxJoint*));
608:  dReal *I = (dReal*) ALLOCA (3*nb*4 * sizeof(dReal));
609:  dReal *invI = (dReal*) ALLOCA (3*nb*4 * sizeof(dReal));
647:  dxJoint::Info1 *info = (dxJoint::Info1*) ALLOCA (nj*sizeof(dxJoint::Info1)
);
648:  int *ofs = (int*) ALLOCA (nj*sizeof(int));
682:  dReal *cforce = (dReal*) ALLOCA (nb*8 * sizeof(dReal));
690:    dReal *c = (dReal*) ALLOCA (m*sizeof(dReal));
691:    dReal *cfm = (dReal*) ALLOCA (m*sizeof(dReal));
692:    dReal *lo = (dReal*) ALLOCA (m*sizeof(dReal));
693:    dReal *hi = (dReal*) ALLOCA (m*sizeof(dReal));
694:    int *findex = (int*) alloca (m*sizeof(int));
721:    dReal *J = (dReal*) ALLOCA (2*m*8*sizeof(dReal));
750:    dReal *JinvM = (dReal*) ALLOCA (2*m*8*sizeof(dReal));
796:    dReal *A = (dReal*) ALLOCA (m*mskip*sizeof(dReal));
854:    dReal *tmp1 = (dReal*) ALLOCA (nb*8 * sizeof(dReal));
866:    dReal *rhs = (dReal*) ALLOCA (m * sizeof(dReal));
890:    dReal *lambda = (dReal*) ALLOCA (m * sizeof(dReal));
891:    dReal *residual = (dReal*) ALLOCA (m * sizeof(dReal));
900://    dReal *L = (dReal*) ALLOCA (m*mskip*sizeof(dReal));
912://    dReal *lambda = (dReal*) ALLOCA (m * sizeof(dReal));
964:  dReal *tmp_vnew = (dReal*) ALLOCA (nb*6*sizeof(dReal));
1007:  dxBody *state = (dxBody*) ALLOCA (nb*sizeof(dxBody));