From b925618e0866b0f2dbbd85ad2134d1d43666633b Mon Sep 17 00:00:00 2001
From: David Malcolm <dmalcolm@redhat.com>
Date: Tue, 9 Jun 2020 13:33:41 -0400
Subject: [PATCH 219/315] FIXME: reject attempts to set sm-state or constraints
 involving UNKNOWN

---
 gcc/analyzer/constraint-manager2.cc | 15 +++++++++++++++
 gcc/analyzer/program-state.cc       |  5 +++++
 2 files changed, 20 insertions(+)

diff --git a/gcc/analyzer/constraint-manager2.cc b/gcc/analyzer/constraint-manager2.cc
index 34f753124a9..a8779f35e71 100644
--- a/gcc/analyzer/constraint-manager2.cc
+++ b/gcc/analyzer/constraint-manager2.cc
@@ -665,6 +665,13 @@ constraint_manager2::add_constraint (const svalue2 *lhs,
 {
   lhs = lhs->unwrap_any_unmergeable ();
   rhs = rhs->unwrap_any_unmergeable ();
+
+  /* Nothing can be known about unknown values.  */
+  if (lhs->get_kind () == svalue2::SK_UNKNOWN
+      || rhs->get_kind () == svalue2::SK_UNKNOWN)
+    /* Not a contradiction.  */
+    return true;
+
   equiv_class2_id lhs_ec_id = get_or_add_equiv_class2 (lhs);
   equiv_class2_id rhs_ec_id = get_or_add_equiv_class2 (rhs);
   return add_constraint (lhs_ec_id, op,rhs_ec_id);
@@ -943,6 +950,8 @@ constraint_manager2::get_or_add_equiv_class2 (const svalue2 *sval)
 {
   equiv_class2_id result (-1);
 
+  gcc_assert (sval->get_kind () != svalue2::SK_UNKNOWN);
+
   /* Try svalue2 match.  */
   if (get_equiv_class2_by_svalue2 (sval, &result))
     return result;
@@ -1086,6 +1095,12 @@ constraint_manager2::eval_condition (const svalue2 *lhs,
 {
   lhs = lhs->unwrap_any_unmergeable ();
   rhs = rhs->unwrap_any_unmergeable ();
+
+  /* Nothing can be known about unknown values.  */
+  if (lhs->get_kind () == svalue2::SK_UNKNOWN
+      || rhs->get_kind () == svalue2::SK_UNKNOWN)
+    return tristate (tristate::TS_UNKNOWN);
+
   return eval_condition (get_or_add_equiv_class2 (lhs),
 			 op,
 			 get_or_add_equiv_class2 (rhs));
diff --git a/gcc/analyzer/program-state.cc b/gcc/analyzer/program-state.cc
index c05a200fe0e..ebe4452e475 100644
--- a/gcc/analyzer/program-state.cc
+++ b/gcc/analyzer/program-state.cc
@@ -786,6 +786,11 @@ sm_state_map2::set_state (region_model2 *model,
 {
   if (model == NULL)
     return;
+
+  /* Reject attempts to set state on UNKNOWN.  */
+  if (sval->get_kind () == svalue2::SK_UNKNOWN)
+    return;
+
   equiv_class2 &ec = model->get_constraints2 ()->get_equiv_class2 (sval);
   if (!set_state (ec, state, origin))
     return;
-- 
2.26.2