isl_ast_build_eliminate_divs: remove unknown divs before divs involving depth

Occasionally, eliminating unknown divs may turn other unknown divs
into known divs, which may depend on the current depth.

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

diff --git a/isl_ast_build.c b/isl_ast_build.c
index 5209f1f..a1941f8 100644 (file)
--- a/isl_ast_build.c
+++ b/isl_ast_build.c
@@ -1982,6 +1982,11 @@ __isl_give isl_set *isl_ast_build_eliminate_inner(
 }
 
 /* Eliminate unknown divs and divs that depend on the current dimension.
+ *
+ * Note that during the elimination of unknown divs, we may discover
+ * an explicit representation of some other unknown divs, which may
+ * depend on the current dimension.  We therefore need to eliminate
+ * unknown divs first.
  */
 __isl_give isl_set *isl_ast_build_eliminate_divs(
        __isl_keep isl_ast_build *build, __isl_take isl_set *set)
@@ -1991,9 +1996,9 @@ __isl_give isl_set *isl_ast_build_eliminate_divs(
        if (!build)
                return isl_set_free(set);
 
+       set = isl_set_remove_unknown_divs(set);
        depth = build->depth;
        set = isl_set_remove_divs_involving_dims(set, isl_dim_set, depth, 1);
-       set = isl_set_remove_unknown_divs(set);
 
        return set;
 }