add isl_aff_gist

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>

diff --git a/doc/user.pod b/doc/user.pod
index 2ffad9a..a47b77b 100644 (file)
--- a/doc/user.pod
+++ b/doc/user.pod
@@ -2264,6 +2264,9 @@ Operations include
        __isl_give isl_aff *isl_aff_scale_down_ui(
                __isl_take isl_aff *aff, unsigned f);
 
+       __isl_give isl_aff *isl_aff_gist(__isl_take isl_aff *aff,
+               __isl_take isl_set *context);
+
 An expression can be printed using
 
        #include <isl/aff.h>

diff --git a/include/isl/aff.h b/include/isl/aff.h
index d7d1f86..f5ddee7 100644 (file)
--- a/include/isl/aff.h
+++ b/include/isl/aff.h
@@ -4,6 +4,7 @@
 #include <isl/div.h>
 #include <isl/local_space.h>
 #include <isl/printer.h>
+#include <isl/set_type.h>
 
 #if defined(__cplusplus)
 extern "C" {
@@ -63,6 +64,9 @@ __isl_give isl_aff *isl_aff_scale(__isl_take isl_aff *aff, isl_int f);
 __isl_give isl_aff *isl_aff_scale_down(__isl_take isl_aff *aff, isl_int f);
 __isl_give isl_aff *isl_aff_scale_down_ui(__isl_take isl_aff *aff, unsigned f);
 
+__isl_give isl_aff *isl_aff_gist(__isl_take isl_aff *aff,
+       __isl_take isl_set *context);
+
 __isl_give isl_printer *isl_printer_print_aff(__isl_take isl_printer *p,
        __isl_keep isl_aff *aff);
 void isl_aff_dump(__isl_keep isl_aff *aff);

diff --git a/isl_aff.c b/isl_aff.c
index 5cd56b9..e258941 100644 (file)
--- a/isl_aff.c
+++ b/isl_aff.c
@@ -8,6 +8,7 @@
  * 91893 Orsay, France
  */
 
+#include <isl_map_private.h>
 #include <isl_aff_private.h>
 #include <isl_local_space_private.h>
 #include <isl_mat_private.h>
@@ -639,3 +640,83 @@ __isl_give isl_aff *isl_aff_set_dim_name(__isl_take isl_aff *aff,
 
        return aff;
 }
+
+/* Exploit the equalities in "eq" to simplify the affine expression
+ * and the expressions of the integer divisions in the local space.
+ * The integer divisions in this local space are assumed to appear
+ * as regular dimensions in "eq".
+ */
+static __isl_give isl_aff *isl_aff_substitute_equalities(
+       __isl_take isl_aff *aff, __isl_take isl_basic_set *eq)
+{
+       int i, j;
+       unsigned total;
+       unsigned n_div;
+
+       if (!eq)
+               goto error;
+       if (eq->n_eq == 0) {
+               isl_basic_set_free(eq);
+               return aff;
+       }
+
+       aff = isl_aff_cow(aff);
+       if (!aff)
+               goto error;
+
+       aff->ls = isl_local_space_substitute_equalities(aff->ls,
+                                                       isl_basic_set_copy(eq));
+       if (!aff->ls)
+               goto error;
+
+       total = 1 + isl_dim_total(eq->dim);
+       n_div = eq->n_div;
+       for (i = 0; i < eq->n_eq; ++i) {
+               j = isl_seq_last_non_zero(eq->eq[i], total + n_div);
+               if (j < 0 || j == 0 || j >= total)
+                       continue;
+
+               isl_seq_elim(aff->v->el + 1, eq->eq[i], j, total,
+                               &aff->v->el[0]);
+       }
+
+       isl_basic_set_free(eq);
+       return aff;
+error:
+       isl_basic_set_free(eq);
+       isl_aff_free(aff);
+       return NULL;
+}
+
+/* Look for equalities among the variables shared by context and aff
+ * and the integer divisions of aff, if any.
+ * The equalities are then used to eliminate coefficients and/or integer
+ * divisions from aff.
+ */
+__isl_give isl_aff *isl_aff_gist(__isl_take isl_aff *aff,
+       __isl_take isl_set *context)
+{
+       isl_basic_set *hull;
+       int n_div;
+
+       if (!aff)
+               goto error;
+       n_div = isl_local_space_dim(aff->ls, isl_dim_div);
+       if (n_div > 0) {
+               isl_basic_set *bset;
+               context = isl_set_add_dims(context, isl_dim_set, n_div);
+               bset = isl_basic_set_from_local_space(
+                                           isl_aff_get_local_space(aff));
+               bset = isl_basic_set_lift(bset);
+               bset = isl_basic_set_flatten(bset);
+               context = isl_set_intersect(context,
+                                           isl_set_from_basic_set(bset));
+       }
+
+       hull = isl_set_affine_hull(context);
+       return isl_aff_substitute_equalities(aff, hull);
+error:
+       isl_aff_free(aff);
+       isl_set_free(context);
+       return NULL;
+}

diff --git a/isl_test.c b/isl_test.c
index f9c9fe2..e458e58 100644 (file)
--- a/isl_test.c
+++ b/isl_test.c
@@ -2229,6 +2229,43 @@ int test_injective(isl_ctx *ctx)
        return 0;
 }
 
+int test_aff(isl_ctx *ctx)
+{
+       const char *str;
+       isl_set *set;
+       isl_dim *dim;
+       isl_local_space *ls;
+       isl_aff *aff;
+       int zero;
+
+       dim = isl_dim_set_alloc(ctx, 0, 1);
+       ls = isl_local_space_from_dim(dim);
+       aff = isl_aff_zero(ls);
+
+       aff = isl_aff_add_coefficient_si(aff, isl_dim_set, 0, 1);
+       aff = isl_aff_scale_down_ui(aff, 3);
+       aff = isl_aff_floor(aff);
+       aff = isl_aff_add_coefficient_si(aff, isl_dim_set, 0, 1);
+       aff = isl_aff_scale_down_ui(aff, 2);
+       aff = isl_aff_floor(aff);
+       aff = isl_aff_add_coefficient_si(aff, isl_dim_set, 0, 1);
+
+       str = "{ [10] }";
+       set = isl_set_read_from_str(ctx, str, 0);
+       aff = isl_aff_gist(aff, set);
+
+       aff = isl_aff_add_constant_si(aff, -16);
+       zero = isl_aff_plain_is_zero(aff);
+       isl_aff_free(aff);
+
+       if (zero < 0)
+               return -1;
+       if (!zero)
+               isl_die(ctx, isl_error_unknown, "unexpected result", return -1);
+
+       return 0;
+}
+
 int main()
 {
        struct isl_ctx *ctx;
@@ -2237,6 +2274,8 @@ int main()
        assert(srcdir);
 
        ctx = isl_ctx_alloc();
+       if (test_aff(ctx) < 0)
+               goto error;
        if (test_injective(ctx) < 0)
                goto error;
        if (test_schedule(ctx) < 0)