Well-formedness check for decl and dead instructions

Check that declared/removed symbol is known and the statement is valid.

src/goto-programs/goto_program.cpp

@@ -676,6 +676,8 @@ void goto_programt::instructiont::validate(
   validate_full_code(code, ns, vm);
   validate_full_expr(guard, ns, vm);
 
+  const symbolt *table_symbol;
+
   switch(type)
   {
   case NO_INSTRUCTION_TYPE:
@@ -713,8 +715,30 @@ void goto_programt::instructiont::validate(
       vm, targets.empty(), "assign instruction should not have a target");
     break;
   case DECL:
+    DATA_CHECK_WITH_DIAGNOSTICS(
+      vm,
+      code.get_statement() == ID_decl,
+      "declaration instructions should contain a declaration statement",
+      source_location);
+    DATA_CHECK_WITH_DIAGNOSTICS(
+      vm,
+      !ns.lookup(to_code_decl(code).get_identifier(), table_symbol),
+      "declared symbols should be known",
+      id2string(to_code_decl(code).get_identifier()),
+      source_location);
     break;
   case DEAD:
+    DATA_CHECK_WITH_DIAGNOSTICS(
+      vm,
+      code.get_statement() == ID_dead,
+      "dead instructions should contain a dead statement",
+      source_location);
+    DATA_CHECK_WITH_DIAGNOSTICS(
+      vm,
+      !ns.lookup(to_code_dead(code).get_identifier(), table_symbol),
+      "removed symbols should be known",
+      id2string(to_code_dead(code).get_identifier()),
+      source_location);
     break;
   case FUNCTION_CALL:
     break;

src/util/std_code.h

@@ -371,6 +371,19 @@ public:
   {
     return symbol().get_identifier();
   }
+
+  static void check(
+    const codet &code,
+    const validation_modet vm = validation_modet::INVARIANT)
+  {
+    DATA_CHECK(
+      vm, code.operands().size() == 1, "declaration must have one operand");
+    DATA_CHECK(
+      vm,
+      code.op0().id() == ID_symbol,
+      "declaring a non-symbol: " +
+        id2string(to_symbol_expr(code.op0()).get_identifier()));
+  }
 };
 
 template<> inline bool can_cast_expr<code_declt>(const exprt &base)
@@ -430,6 +443,21 @@ public:
   {
     return symbol().get_identifier();
   }
+
+  static void check(
+    const codet &code,
+    const validation_modet vm = validation_modet::INVARIANT)
+  {
+    DATA_CHECK(
+      vm,
+      code.operands().size() == 1,
+      "removal (code_deadt) must have one operand");
+    DATA_CHECK(
+      vm,
+      code.op0().id() == ID_symbol,
+      "removing a non-symbol: " +
+        id2string(to_symbol_expr(code.op0()).get_identifier()) + "from scope");
+  }
 };
 
 template<> inline bool can_cast_expr<code_deadt>(const exprt &base)

src/util/validate_code.cpp

@@ -31,6 +31,10 @@ void call_on_code(const codet &code, Args &&... args)
   {
     CALL_ON_CODE(code_declt);
   }
+  else if(code.get_statement() == ID_dead)
+  {
+    CALL_ON_CODE(code_deadt);
+  }
   else
   {
 #ifdef REPORT_UNIMPLEMENTED_CODE_CHECKS

unit/Makefile

@@ -15,6 +15,8 @@ SRC += analyses/ai/ai.cpp \
        analyses/does_remove_const/does_type_preserve_const_correctness.cpp \
        analyses/does_remove_const/is_type_at_least_as_const_as.cpp \
        compound_block_locations.cpp \
+       goto-programs/goto_program_dead.cpp \
+       goto-programs/goto_program_declaration.cpp \
        goto-programs/goto_trace_output.cpp \
        goto-symex/ssa_equation.cpp \
        interpreter/interpreter.cpp \

unit/goto-programs/goto_program_dead.cpp

@@ -0,0 +1,66 @@
+/*******************************************************************\
+
+  Module: Unit tests for goto_program::validate
+
+  Author: Diffblue Ltd.
+
+ \*******************************************************************/
+
+#include <goto-programs/goto_function.h>
+#include <testing-utils/catch.hpp>
+#include <util/arith_tools.h>
+
+SCENARIO(
+  "Validation of well-formed symbol removing codes",
+  "[core][goto-programs][validate]")
+{
+  GIVEN("A program with one symbol removal")
+  {
+    symbol_tablet symbol_table;
+    const signedbv_typet type1(32);
+
+    symbolt var_symbol;
+    irep_idt var_symbol_name = "a";
+    var_symbol.type = type1;
+    var_symbol.name = var_symbol_name;
+    symbol_exprt var_a(var_symbol_name, type1);
+
+    goto_functiont goto_function;
+    auto &instructions = goto_function.body.instructions;
+    instructions.emplace_back(goto_program_instruction_typet::DEAD);
+    code_deadt removal(var_a);
+    instructions.back().make_dead();
+    instructions.back().code = removal;
+
+    WHEN("Removing known symbol")
+    {
+      symbol_table.insert(var_symbol);
+      const namespacet ns(symbol_table);
+
+      THEN("The consistency check succeeds")
+      {
+        goto_function.body.validate(ns, validation_modet::INVARIANT);
+        REQUIRE(true);
+      }
+    }
+
+    WHEN("Removing unknown symbol")
+    {
+      const namespacet ns(symbol_table);
+
+      THEN("The consistency check fails")
+      {
+        bool caught = false;
+        try
+        {
+          goto_function.body.validate(ns, validation_modet::EXCEPTION);
+        }
+        catch(incorrect_goto_program_exceptiont &e)
+        {
+          caught = true;
+        }
+        REQUIRE(caught);
+      }
+    }
+  }
+}

unit/goto-programs/goto_program_declaration.cpp

@@ -0,0 +1,65 @@
+/*******************************************************************\
+
+  Module: Unit tests for goto_program::validate
+
+  Author: Diffblue Ltd.
+
+ \*******************************************************************/
+
+#include <goto-programs/goto_function.h>
+#include <testing-utils/catch.hpp>
+#include <util/arith_tools.h>
+
+SCENARIO(
+  "Validation of well-formed declaration codes",
+  "[core][goto-programs][validate]")
+{
+  GIVEN("A program with one declaration")
+  {
+    symbol_tablet symbol_table;
+    const signedbv_typet type1(32);
+
+    symbolt var_symbol;
+    irep_idt var_symbol_name = "a";
+    var_symbol.type = type1;
+    var_symbol.name = var_symbol_name;
+    symbol_exprt var_a(var_symbol_name, type1);
+
+    goto_functiont goto_function;
+    auto &instructions = goto_function.body.instructions;
+    instructions.emplace_back(goto_program_instruction_typet::DECL);
+    code_declt declaration(var_a);
+    instructions.back().make_decl(declaration);
+
+    WHEN("Declaring known symbol")
+    {
+      symbol_table.insert(var_symbol);
+      const namespacet ns(symbol_table);
+
+      THEN("The consistency check succeeds")
+      {
+        goto_function.body.validate(ns, validation_modet::INVARIANT);
+        REQUIRE(true);
+      }
+    }
+
+    WHEN("Declaring unknown symbol")
+    {
+      const namespacet ns(symbol_table);
+
+      THEN("The consistency check fails")
+      {
+        bool caught = false;
+        try
+        {
+          goto_function.body.validate(ns, validation_modet::EXCEPTION);
+        }
+        catch(incorrect_goto_program_exceptiont &e)
+        {
+          caught = true;
+        }
+        REQUIRE(caught);
+      }
+    }
+  }
+}