/* Set the stride and offset of data->pos to the given
* value and expression.
*
* If we had already found a stride before, then the two strides
* are combined into a single stride.
*
* In particular, if the new stride information is of the form
*
* i = f + s (...)
*
* and the old stride information is of the form
*
* i = f2 + s2 (...)
*
* then we compute the extended gcd of s and s2
*
* a s + b s2 = g,
*
* with g = gcd(s,s2), multiply the first equation with t1 = b s2/g
* and the second with t2 = a s1/g.
* This results in
*
* i = (b s2 + a s1)/g i = t1 f + t2 f2 + (s s2)/g (...)
*
* so that t1 f + t2 f2 is the combined offset and (s s2)/g = lcm(s,s2)
* is the combined stride.
*/
static isl_stat set_stride(struct isl_detect_stride_data *data,
__isl_take isl_val *stride, __isl_take isl_aff *offset)
{
int pos;
if (!stride || !offset)
goto error;
pos = data->pos;
if (data->found) {
isl_val *stride2, *a, *b, *g;
isl_aff *offset2;
stride2 = data->stride;
g = isl_val_gcdext(isl_val_copy(stride), isl_val_copy(stride2),
&a, &b);
a = isl_val_mul(a, isl_val_copy(stride));
a = isl_val_div(a, isl_val_copy(g));
stride2 = isl_val_div(stride2, g);
b = isl_val_mul(b, isl_val_copy(stride2));
stride = isl_val_mul(stride, stride2);
if (!data->want_offset) {
isl_val_free(a);
isl_val_free(b);
} else {
offset2 = data->offset;
offset2 = isl_aff_scale_val(offset2, a);
offset = isl_aff_scale_val(offset, b);
offset = isl_aff_add(offset, offset2);
}
}
data->found = 1;
data->stride = stride;
if (data->want_offset)
data->offset = offset;
else
isl_aff_free(offset);
if (!data->stride || (data->want_offset && !data->offset))
return isl_stat_error;
return isl_stat_ok;
error:
isl_val_free(stride);
isl_aff_free(offset);
return isl_stat_error;
}
static isl_constraint *
build_linearized_memory_access (isl_map *map, poly_dr_p pdr)
{
isl_constraint *res;
isl_local_space *ls = isl_local_space_from_space (isl_map_get_space (map));
unsigned offset, nsubs;
int i;
isl_ctx *ctx;
isl_val *size, *subsize, *size1;
res = isl_equality_alloc (ls);
ctx = isl_local_space_get_ctx (ls);
size = isl_val_int_from_ui (ctx, 1);
nsubs = isl_set_dim (pdr->extent, isl_dim_set);
/* -1 for the already included L dimension. */
offset = isl_map_dim (map, isl_dim_out) - 1 - nsubs;
res = isl_constraint_set_coefficient_si (res, isl_dim_out, offset + nsubs, -1);
/* Go through all subscripts from last to first. First dimension
is the alias set, ignore it. */
for (i = nsubs - 1; i >= 1; i--)
{
isl_space *dc;
isl_aff *aff;
size1 = isl_val_copy (size);
res = isl_constraint_set_coefficient_val (res, isl_dim_out, offset + i, size);
dc = isl_set_get_space (pdr->extent);
aff = isl_aff_zero_on_domain (isl_local_space_from_space (dc));
aff = isl_aff_set_coefficient_si (aff, isl_dim_in, i, 1);
subsize = isl_set_max_val (pdr->extent, aff);
isl_aff_free (aff);
size = isl_val_mul (size1, subsize);
}
isl_val_free (size);
return res;
}
