Merge pull request #940 from cristina-david/feature/uncaught-exceptions

Uncaught exceptions analysis

Author: mgudemann

regression/cbmc-java/virtual7/test.desc

@@ -3,9 +3,9 @@ test.class
 --show-goto-functions
 ^EXIT=0$
 ^SIGNAL=0$
-IF "java::E".*THEN GOTO [67]
-IF "java::B".*THEN GOTO [67]
-IF "java::D".*THEN GOTO [67]
-IF "java::C".*THEN GOTO [67]
+IF "java::E".*THEN GOTO [12]
+IF "java::B".*THEN GOTO [12]
+IF "java::D".*THEN GOTO [12]
+IF "java::C".*THEN GOTO [12]
 --
 IF "java::A".*THEN GOTO

src/analyses/Makefile

@@ -24,6 +24,7 @@ SRC = ai.cpp \
       reaching_definitions.cpp \
       replace_symbol_ext.cpp \
       static_analysis.cpp \
+      uncaught_exceptions_analysis.cpp \
       uninitialized_domain.cpp \
       # Empty last line
 

src/analyses/uncaught_exceptions_analysis.cpp

@@ -0,0 +1,335 @@
+/*******************************************************************\
+
+Module: Over-approximating uncaught exceptions analysis
+
+Author: Cristina David
+
+\*******************************************************************/
+
+#ifdef DEBUG
+#include <iostream>
+#endif
+#include "uncaught_exceptions_analysis.h"
+
+/*******************************************************************\
+
+Function: get_exception_type
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Returns the compile type of an exception
+
+\*******************************************************************/
+
+irep_idt uncaught_exceptions_domaint::get_exception_type(const typet &type)
+{
+  assert(type.id()==ID_pointer);
+
+  if(type.subtype().id()==ID_symbol)
+  {
+    return to_symbol_type(type.subtype()).get_identifier();
+  }
+  return ID_empty;
+}
+
+/*******************************************************************\
+
+Function: get_exception_symbol
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Returns the symbol corresponding to an exception
+
+\*******************************************************************/
+
+exprt uncaught_exceptions_domaint::get_exception_symbol(const exprt &expr)
+{
+  if(expr.id()!=ID_symbol && expr.has_operands())
+    return get_exception_symbol(expr.op0());
+
+  return expr;
+}
+
+/*******************************************************************\
+
+Function: uncaught_exceptions_domaint::join
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: The join operator for the uncaught exceptions domain
+
+\*******************************************************************/
+
+void uncaught_exceptions_domaint::join(
+  const irep_idt &element)
+{
+  thrown.insert(element);
+}
+
+void uncaught_exceptions_domaint::join(
+  const std::set<irep_idt> &elements)
+{
+  thrown.insert(elements.begin(), elements.end());
+}
+
+void uncaught_exceptions_domaint::join(
+  const std::vector<irep_idt> &elements)
+{
+  thrown.insert(elements.begin(), elements.end());
+}
+
+
+/*******************************************************************\
+
+Function: uncaught_exceptions_domaint::transform
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: The transformer for the uncaught exceptions domain
+
+\*******************************************************************/
+
+void uncaught_exceptions_domaint::transform(
+  const goto_programt::const_targett from,
+  uncaught_exceptions_analysist &uea,
+  const namespacet &ns)
+{
+  const goto_programt::instructiont &instruction=*from;
+
+  switch(instruction.type)
+  {
+  case THROW:
+  {
+    const exprt &exc_symbol=get_exception_symbol(instruction.code);
+    // retrieve the static type of the thrown exception
+    const irep_idt &type_id=get_exception_type(exc_symbol.type());
+    bool assertion_error=
+      id2string(type_id).find("java.lang.AssertionError")!=std::string::npos;
+    if(!assertion_error)
+    {
+      join(type_id);
+      // we must consider all the subtypes given that
+      // the runtime type is a subtype of the static type
+      std::vector<irep_idt> subtypes=
+        class_hierarchy.get_children_trans(type_id);
+      join(subtypes);
+    }
+    break;
+  }
+  case CATCH:
+  {
+    if(!instruction.code.has_operands())
+    {
+      if(!instruction.targets.empty()) // push
+      {
+        std::set<irep_idt> caught;
+        stack_caught.push_back(caught);
+        std::set<irep_idt> &last_caught=stack_caught.back();
+        const irept::subt &exception_list=
+          instruction.code.find(ID_exception_list).get_sub();
+
+        for(const auto &exc : exception_list)
+        {
+          last_caught.insert(exc.id());
+          std::vector<irep_idt> subtypes=
+            class_hierarchy.get_children_trans(exc.id());
+          last_caught.insert(subtypes.begin(), subtypes.end());
+        }
+      }
+      else // pop
+      {
+        if(!stack_caught.empty())
+        {
+          const std::set<irep_idt> &caught=stack_caught.back();
+          join(caught);
+          // remove the caught exceptions
+          for(const auto &exc_id : caught)
+            thrown.erase(exc_id);
+          stack_caught.pop_back();
+        }
+      }
+    }
+    break;
+  }
+  case FUNCTION_CALL:
+  {
+    const exprt &function_expr=
+      to_code_function_call(instruction.code).function();
+    assert(function_expr.id()==ID_symbol);
+    const irep_idt &function_name=
+      to_symbol_expr(function_expr).get_identifier();
+    // use the current information about the callee
+    join(uea.exceptions_map[function_name]);
+    break;
+  }
+  default:
+  {}
+  }
+}
+
+/*******************************************************************\
+
+Function: uncaught_exceptions_domaint::get_elements
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Returns the value of the private member thrown
+
+\*******************************************************************/
+
+const std::set<irep_idt> &uncaught_exceptions_domaint::get_elements() const
+{
+  return thrown;
+}
+
+/*******************************************************************\
+
+Function: uncaught_exceptions_domaint::operator()
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Constructs the class hierarchy
+
+\*******************************************************************/
+
+void uncaught_exceptions_domaint::operator()(
+  const namespacet &ns)
+{
+  class_hierarchy(ns.get_symbol_table());
+}
+
+/*******************************************************************\
+
+Function: uncaught_exceptions_analysist::collect_uncaught_exceptions
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Runs the uncaught exceptions analysis, which 
+          populates the exceptions map
+
+\*******************************************************************/
+
+void uncaught_exceptions_analysist::collect_uncaught_exceptions(
+  const goto_functionst &goto_functions,
+  const namespacet &ns)
+{
+  bool change=true;
+
+  while(change)
+  {
+    change=false;
+    // add all the functions to the worklist
+    forall_goto_functions(current_function, goto_functions)
+    {
+      domain.make_top();
+      const goto_programt &goto_program=current_function->second.body;
+
+      if(goto_program.empty())
+        continue;
+
+      forall_goto_program_instructions(instr_it, goto_program)
+      {
+        domain.transform(instr_it, *this, ns);
+      }
+      // did our estimation for the current function improve?
+      const std::set<irep_idt> &elements=domain.get_elements();
+      if(exceptions_map[current_function->first].size()<elements.size())
+      {
+        change=true;
+        exceptions_map[current_function->first]=elements;
+      }
+    }
+  }
+}
+
+/*******************************************************************\
+
+Function: uncaught_exceptions_analysist::output
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Prints the exceptions map that maps each method to the 
+          set of exceptions that may escape it
+
+\*******************************************************************/
+
+void uncaught_exceptions_analysist::output(
+  const goto_functionst &goto_functions)
+{
+#ifdef DEBUG
+  forall_goto_functions(it, goto_functions)
+  {
+    if(exceptions_map[it->first].size()>0)
+    {
+      std::cout << "Uncaught exceptions in function " <<
+        it->first << ": " << std::endl;
+      assert(exceptions_map.find(it->first)!=exceptions_map.end());
+      for(auto exc_id : exceptions_map[it->first])
+        std::cout << id2string(exc_id) << " ";
+      std::cout << std::endl;
+    }
+  }
+#endif
+}
+
+/*******************************************************************\
+
+Function: uncaught_exceptions_analysist::operator()
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Applies the uncaught exceptions analysis and 
+          outputs the result
+
+\*******************************************************************/
+
+void uncaught_exceptions_analysist::operator()(
+  const goto_functionst &goto_functions,
+  const namespacet &ns,
+  exceptions_mapt &exceptions)
+{
+  domain(ns);
+  collect_uncaught_exceptions(goto_functions, ns);
+  exceptions=exceptions_map;
+  output(goto_functions);
+}
+
+/*******************************************************************\
+
+Function: uncaught_exceptions
+
+  Inputs:
+
+ Outputs:
+
+ Purpose: Applies the uncaught exceptions analysis and 
+          outputs the result
+
+\*******************************************************************/
+
+void uncaught_exceptions(
+  const goto_functionst &goto_functions,
+  const namespacet &ns,
+  std::map<irep_idt, std::set<irep_idt>> &exceptions_map)
+{
+  uncaught_exceptions_analysist exceptions;
+  exceptions(goto_functions, ns, exceptions_map);
+}