handle case where lower bound is above upper

Signed-off-by: Nikolaj Bjorner <[email protected]>
Z3Prover · Sep 20, 2019 · 4101652 · 4101652
1 parent b506e45
commit 4101652
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Showing 2 changed files with 5 additions and 4 deletions.
diff --git a/src/ast/rewriter/seq_rewriter.cpp b/src/ast/rewriter/seq_rewriter.cpp
@@ -1824,6 +1824,10 @@ br_status seq_rewriter::mk_re_loop(func_decl* f, unsigned num_args, expr* const*
     expr* a = nullptr;
     switch (num_args) {
     case 1: 
+        if (f->get_num_parameters() == 2 && f->get_parameter(0).get_int() > f->get_parameter(1).get_int()) {
+            result = m_util.re.mk_loop(args[0], f->get_parameter(1).get_int(), f->get_parameter(1).get_int());
+            return BR_REWRITE1;
+        }
         // (loop (loop a lo hi) lo2 hi2) = (loop lo*lo2 hi*hi2)
         if (m_util.re.is_loop(args[0], a, lo, hi) && f->get_num_parameters() == 2) {
             result = m_util.re.mk_loop(a, f->get_parameter(0).get_int() * lo, f->get_parameter(1).get_int() * hi);
@@ -1864,7 +1868,7 @@ br_status seq_rewriter::mk_re_loop(func_decl* f, unsigned num_args, expr* const*
         break;
     case 3:
         if (m_autil.is_numeral(args[1], n1) && n1.is_unsigned() &&
-            m_autil.is_numeral(args[2], n2) && n2.is_unsigned() && n1 <= n2) {
+            m_autil.is_numeral(args[2], n2) && n2.is_unsigned()) {
             result = m_util.re.mk_loop(args[0], n1.get_unsigned(), n2.get_unsigned());
             return BR_REWRITE1;
         }

diff --git a/src/ast/seq_decl_plugin.cpp b/src/ast/seq_decl_plugin.cpp
@@ -747,9 +747,6 @@ func_decl * seq_decl_plugin::mk_func_decl(decl_kind k, unsigned num_parameters,
             if (num_parameters == 0 || num_parameters > 2 || !parameters[0].is_int() || (num_parameters == 2 && !parameters[1].is_int())) {
                 m.raise_exception("Expecting two numeral parameters to function re-loop");
             }
-            if (num_parameters == 2 && parameters[0].get_int() > parameters[1].get_int()) {
-                m.raise_exception("Lower bound cannot be higher than upper bound in loop specfication");
-            }
             return m.mk_func_decl(m_sigs[k]->m_name, arity, domain, rng, func_decl_info(m_family_id, k, num_parameters, parameters));
         case 2:
             if (m_re != domain[0] || !arith_util(m).is_int(domain[1])) {