[PATCH 24/45] analyzer: new files: tristate.{cc|h}

[David Malcolm <dmalcolm@redhat.com>]

Changed in v4:
- moved from gcc/analyzer to gcc

gcc/ChangeLog:
	* tristate.cc: New file.
	* tristate.h: New file.
---
 gcc/tristate.cc | 221 ++++++++++++++++++++++++++++++++++++++++++++++++
 gcc/tristate.h  |  82 ++++++++++++++++++
 2 files changed, 303 insertions(+)
 create mode 100644 gcc/tristate.cc
 create mode 100644 gcc/tristate.h

diff --git a/gcc/tristate.cc b/gcc/tristate.cc
new file mode 100644
index 000000000000..78217f196804
--- /dev/null
+++ b/gcc/tristate.cc
@@ -0,0 +1,221 @@
+/* "True" vs "False" vs "Unknown".
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   Contributed by David Malcolm <dmalcolm@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tristate.h"
+#include "selftest.h"
+
+const char *
+tristate::as_string () const
+{
+  switch (m_value)
+    {
+    default:
+      gcc_unreachable ();
+    case TS_UNKNOWN:
+      return "UNKNOWN";
+    case TS_TRUE:
+      return "TRUE";
+    case TS_FALSE:
+      return "FALSE";
+    }
+}
+
+tristate
+tristate::not_ () const
+{
+  switch (m_value)
+    {
+    default:
+      gcc_unreachable ();
+    case TS_UNKNOWN:
+      return tristate (TS_UNKNOWN);
+    case TS_TRUE:
+      return tristate (TS_FALSE);
+    case TS_FALSE:
+      return tristate (TS_TRUE);
+    }
+}
+
+tristate
+tristate::or_ (tristate other) const
+{
+  switch (m_value)
+    {
+    default:
+      gcc_unreachable ();
+    case TS_UNKNOWN:
+      if (other.is_true ())
+	return tristate (TS_TRUE);
+      else
+	return tristate (TS_UNKNOWN);
+    case TS_FALSE:
+      return other;
+    case TS_TRUE:
+      return tristate (TS_TRUE);
+    }
+}
+
+tristate
+tristate::and_ (tristate other) const
+{
+  switch (m_value)
+    {
+    default:
+      gcc_unreachable ();
+    case TS_UNKNOWN:
+      if (other.is_false ())
+	return tristate (TS_FALSE);
+      else
+	return tristate (TS_UNKNOWN);
+    case TS_TRUE:
+      return other;
+    case TS_FALSE:
+      return tristate (TS_FALSE);
+    }
+}
+
+#if CHECKING_P
+
+namespace selftest {
+
+#define ASSERT_TRISTATE_TRUE(TRISTATE) \
+  SELFTEST_BEGIN_STMT					\
+  ASSERT_EQ (TRISTATE, tristate (tristate::TS_TRUE));	\
+  SELFTEST_END_STMT
+
+#define ASSERT_TRISTATE_FALSE(TRISTATE) \
+  SELFTEST_BEGIN_STMT					\
+  ASSERT_EQ (TRISTATE, tristate (tristate::TS_FALSE));	\
+  SELFTEST_END_STMT
+
+#define ASSERT_TRISTATE_UNKNOWN(TRISTATE) \
+  SELFTEST_BEGIN_STMT						\
+  ASSERT_EQ (TRISTATE, tristate (tristate::TS_UNKNOWN));	\
+  SELFTEST_END_STMT
+
+/* Test tristate's ctors, along with is_*, as_string, operator==, and
+   operator!=.  */
+
+static void
+test_ctors ()
+{
+  tristate u (tristate::TS_UNKNOWN);
+  ASSERT_FALSE (u.is_known ());
+  ASSERT_FALSE (u.is_true ());
+  ASSERT_FALSE (u.is_false ());
+  ASSERT_STREQ (u.as_string (), "UNKNOWN");
+
+  tristate t (tristate::TS_TRUE);
+  ASSERT_TRUE (t.is_known ());
+  ASSERT_TRUE (t.is_true ());
+  ASSERT_FALSE (t.is_false ());
+  ASSERT_STREQ (t.as_string (), "TRUE");
+
+  tristate f (tristate::TS_FALSE);
+  ASSERT_TRUE (f.is_known ());
+  ASSERT_FALSE (f.is_true ());
+  ASSERT_TRUE (f.is_false ());
+  ASSERT_STREQ (f.as_string (), "FALSE");
+
+  ASSERT_EQ (u, u);
+  ASSERT_EQ (t, t);
+  ASSERT_EQ (f, f);
+  ASSERT_NE (u, t);
+  ASSERT_NE (u, f);
+  ASSERT_NE (t, f);
+
+  tristate t2 (true);
+  ASSERT_TRUE (t2.is_true ());
+  ASSERT_EQ (t, t2);
+
+  tristate f2 (false);
+  ASSERT_TRUE (f2.is_false ());
+  ASSERT_EQ (f, f2);
+
+  tristate u2 (tristate::unknown ());
+  ASSERT_TRUE (!u2.is_known ());
+  ASSERT_EQ (u, u2);
+}
+
+/* Test && on tristate instances.  */
+
+static void
+test_and ()
+{
+  ASSERT_TRISTATE_UNKNOWN (tristate::unknown () && tristate::unknown ());
+
+  ASSERT_TRISTATE_FALSE (tristate (false) && tristate (false));
+  ASSERT_TRISTATE_FALSE (tristate (false) && tristate (true));
+  ASSERT_TRISTATE_FALSE (tristate (true) && tristate (false));
+  ASSERT_TRISTATE_TRUE (tristate (true) && tristate (true));
+
+  ASSERT_TRISTATE_UNKNOWN (tristate::unknown () && tristate (true));
+  ASSERT_TRISTATE_UNKNOWN (tristate (true) && tristate::unknown ());
+
+  ASSERT_TRISTATE_FALSE (tristate::unknown () && tristate (false));
+  ASSERT_TRISTATE_FALSE (tristate (false) && tristate::unknown ());
+}
+
+/* Test || on tristate instances.  */
+
+static void
+test_or ()
+{
+  ASSERT_TRISTATE_UNKNOWN (tristate::unknown () || tristate::unknown ());
+
+  ASSERT_TRISTATE_FALSE (tristate (false) || tristate (false));
+  ASSERT_TRISTATE_TRUE (tristate (false) || tristate (true));
+  ASSERT_TRISTATE_TRUE (tristate (true) || tristate (false));
+  ASSERT_TRISTATE_TRUE (tristate (true) || tristate (true));
+
+  ASSERT_TRISTATE_TRUE (tristate::unknown () || tristate (true));
+  ASSERT_TRISTATE_TRUE (tristate (true) || tristate::unknown ());
+
+  ASSERT_TRISTATE_UNKNOWN (tristate::unknown () || tristate (false));
+  ASSERT_TRISTATE_UNKNOWN (tristate (false) || tristate::unknown ());
+}
+
+/* Test ! on tristate instances.  */
+
+static void
+test_not ()
+{
+  ASSERT_TRISTATE_UNKNOWN (!tristate::unknown ());
+  ASSERT_TRISTATE_FALSE (!tristate (true));
+  ASSERT_TRISTATE_TRUE (!tristate (false));
+}
+
+/* Run all of the selftests within this file.  */
+
+void
+tristate_cc_tests ()
+{
+  test_ctors ();
+  test_and ();
+  test_or ();
+  test_not ();
+}
+
+} // namespace selftest
+
+#endif /* CHECKING_P */
diff --git a/gcc/tristate.h b/gcc/tristate.h
new file mode 100644
index 000000000000..88b96576f6a2
--- /dev/null
+++ b/gcc/tristate.h
@@ -0,0 +1,82 @@
+/* "True" vs "False" vs "Unknown".
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   Contributed by David Malcolm <dmalcolm@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef GCC_ANALYZER_TRISTATE_H
+#define GCC_ANALYZER_TRISTATE_H
+
+/* "True" vs "False" vs "Unknown".  */
+
+class tristate {
+ public:
+  enum value {
+    TS_UNKNOWN,
+    TS_TRUE,
+    TS_FALSE
+  };
+
+  tristate (enum value val) : m_value (val) {}
+  tristate (bool val) : m_value (val ? TS_TRUE : TS_FALSE) {}
+  static tristate unknown () { return tristate (TS_UNKNOWN); }
+
+  const char *as_string () const;
+
+  bool is_known () const { return m_value != TS_UNKNOWN; }
+  bool is_true () const { return m_value == TS_TRUE; }
+  bool is_false () const { return m_value == TS_FALSE; }
+
+  tristate not_ () const;
+  tristate or_ (tristate other) const;
+  tristate and_ (tristate other) const;
+
+  bool operator== (const tristate &other) const
+  {
+    return m_value == other.m_value;
+  }
+
+  bool operator!= (const tristate &other) const
+  {
+    return m_value != other.m_value;
+  }
+
+ private:
+  enum value m_value;
+};
+
+/* Overloaded boolean operators on tristates.  */
+
+inline tristate
+operator ! (tristate t)
+{
+  return t.not_ ();
+}
+
+inline tristate
+operator || (tristate a, tristate b)
+{
+  return a.or_ (b);
+}
+
+inline tristate
+operator && (tristate a, tristate b)
+{
+  return a.and_ (b);
+}
+
+#endif /* GCC_ANALYZER_TRISTATE_H */
-- 
2.21.0