analyzer: add support for plugin-supplied known function behaviors

This patch adds the ability for plugins to register "known functions"
with the analyzer, identified by name.  If -fanalyzer sees a call to
such a function (with no body), it will use a plugin-provided subclass
of the new known_function abstract base class to model the possible
outcomes of the function call.

gcc/ChangeLog:
	* Makefile.in (ANALYZER_OBJS): Add
	analyzer/known-function-manager.o.

gcc/analyzer/ChangeLog:
	* analyzer.h (class known_function_manager): New forward decl.
	(class known_function): New.
	(plugin_analyzer_init_iface::register_known_function): New.
	* engine.cc: Include "analyzer/known-function-manager.h".
	(plugin_analyzer_init_impl::plugin_analyzer_init_impl): Add
	known_fn_mgr param.
	(plugin_analyzer_init_impl::register_state_machine): Add
	LOC_SCOPE.
	(plugin_analyzer_init_impl::register_known_function): New.
	(plugin_analyzer_init_impl::m_known_fn_mgr): New.
	(impl_run_checkers): Update plugin callback invocation to use
	eng's known_function_manager.
	* known-function-manager.cc: New file.
	* known-function-manager.h: New file.
	* region-model-manager.cc
	(region_model_manager::region_model_manager): Pass logger to
	m_known_fn_mgr's ctor.
	* region-model.cc (region_model::update_for_zero_return): New.
	(region_model::update_for_nonzero_return): New.
	(maybe_simplify_upper_bound): New.
	(region_model::maybe_get_copy_bounds): New.
	(region_model::get_known_function): New.
	(region_model::on_call_pre): Handle plugin-supplied known
	functions.
	* region-model.h: Include "analyzer/known-function-manager.h".
	(region_model_manager::get_known_function_manager): New.
	(region_model_manager::m_known_fn_mgr): New.
	(call_details::get_model): New accessor.
	(region_model::maybe_get_copy_bounds): New decl.
	(region_model::update_for_zero_return): New decl.
	(region_model::update_for_nonzero_return): New decl.
	(region_model::get_known_function): New decl.
	(region_model::get_known_function_manager): New.

gcc/testsuite/ChangeLog:
	* gcc.dg/plugin/analyzer_known_fns_plugin.c: New test plugin.
	* gcc.dg/plugin/known-fns-1.c: New test.
	* gcc.dg/plugin/plugin.exp (plugin_test_list): Add the new plugin
	and test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/gcc/analyzer/known-function-manager.cc b/gcc/analyzer/known-function-manager.cc
new file mode 100644
index 0000000..f0fd4fc
--- /dev/null
+++ b/gcc/analyzer/known-function-manager.cc
@@ -0,0 +1,78 @@
+/* Support for plugin-supplied behaviors of known functions.
+   Copyright (C) 2022 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 "tree.h"
+#include "function.h"
+#include "analyzer/analyzer.h"
+#include "diagnostic-core.h"
+#include "analyzer/analyzer-logging.h"
+#include "stringpool.h"
+#include "analyzer/known-function-manager.h"
+
+#if ENABLE_ANALYZER
+
+namespace ana {
+
+/* class known_function_manager : public log_user.  */
+
+known_function_manager::known_function_manager (logger *logger)
+: log_user (logger)
+{
+}
+
+known_function_manager::~known_function_manager ()
+{
+  /* Delete all owned kfs.  */
+  for (auto iter : m_map_id_to_kf)
+    delete iter.second;
+}
+
+void
+known_function_manager::add (const char *name, known_function *kf)
+{
+  LOG_FUNC_1 (get_logger (), "registering %s", name);
+  tree id = get_identifier (name);
+  m_map_id_to_kf.put (id, kf);
+}
+
+const known_function *
+known_function_manager::get_by_identifier (tree identifier)
+{
+  known_function **slot = m_map_id_to_kf.get (identifier);
+  if (slot)
+    return *slot;
+  else
+    return NULL;
+}
+
+const known_function *
+known_function_manager::get_by_fndecl (tree fndecl)
+{
+  if (tree identifier = DECL_NAME (fndecl))
+    return get_by_identifier (identifier);
+  return NULL;
+}
+
+} // namespace ana
+
+#endif /* #if ENABLE_ANALYZER */