Prefix temporary var names with function id

 Temporary variable names must be globally unique and
 changing the number of temporaries in one function
 must not change a variable name in another function.
 Otherwise, this has adverse effects on goto-diff.

 This commit gets rid of various global temporary
 variables counters that do not meet above criteria.
 Instead, we now always use the function id to prefix
 temporaries to eliminate cross-function effects
 and increment the numeric suffix only when the
 entire variable name already exists, using the
 rename facility.

Author: peterschrammel

src/ansi-c/c_nondet_symbol_factory.cpp

@@ -43,8 +43,8 @@ static const symbolt &c_new_tmp_symbol(
   const bool static_lifetime,
   const std::string &prefix="tmp")
 {
-  symbolt &tmp_symbol=
-    get_fresh_aux_symbol(type, "", prefix, loc, ID_C, symbol_table);
+  symbolt &tmp_symbol = get_fresh_aux_symbol(
+    type, id2string(loc.get_function()), prefix, loc, ID_C, symbol_table);
   tmp_symbol.is_static_lifetime=static_lifetime;
 
   return tmp_symbol;

src/goto-instrument/code_contracts.cpp

@@ -250,7 +250,7 @@ const symbolt &code_contractst::new_tmp_symbol(
 {
   return get_fresh_aux_symbol(
     type,
-    "",
+    id2string(source_location.get_function()),
     "tmp_cc",
     source_location,
     irep_idt(),

src/goto-programs/convert_nondet.cpp

@@ -17,6 +17,7 @@ Author: Reuben Thomas, [email protected]
 #include <java_bytecode/java_object_factory.h> // gen_nondet_init
 
 #include <util/irep_ids.h>
+#include <util/fresh_symbol.h>
 
 #include <memory>
 
@@ -135,11 +136,13 @@ void convert_nondet(
   message_handlert &message_handler,
   const object_factory_parameterst &object_factory_parameters)
 {
+  object_factory_parameterst parameters = object_factory_parameters;
+  parameters.function_id = function.get_function_id();
   convert_nondet(
     function.get_goto_function().body,
     function.get_symbol_table(),
     message_handler,
-    object_factory_parameters);
+    parameters);
 
   function.compute_location_numbers();
 }
@@ -158,6 +161,8 @@ void convert_nondet(
 
     if(symbol.mode==ID_java)
     {
+      object_factory_parameterst parameters = object_factory_parameters;
+      parameters.function_id = f_it.first;
       convert_nondet(
         f_it.second.body,
         symbol_table,

src/goto-programs/goto_convert_class.h

@@ -34,7 +34,6 @@ class goto_convertt:public messaget
     messaget(_message_handler),
     symbol_table(_symbol_table),
     ns(_symbol_table),
-    temporary_counter(0),
     tmp_symbol_prefix("goto_convertt")
   {
   }
@@ -46,7 +45,6 @@ class goto_convertt:public messaget
 protected:
   symbol_table_baset &symbol_table;
   namespacet ns;
-  unsigned temporary_counter;
   std::string tmp_symbol_prefix;
 
   void goto_convert_rec(const codet &code, goto_programt &dest);

src/goto-programs/goto_convert_functions.cpp

@@ -147,8 +147,6 @@ void goto_convert_functionst::convert_function(
 
   // make tmp variables local to function
   tmp_symbol_prefix=id2string(symbol.name)+"::$tmp::";
-  temporary_counter=0;
-  reset_temporary_counter();
 
   f.type=to_code_type(symbol.type);
 

src/goto-programs/goto_convert_side_effect.cpp

@@ -379,14 +379,15 @@ void goto_convertt::remove_function_call(
 
     new_base_name+='_';
     new_base_name+=id2string(symbol.base_name);
-    new_base_name+="$"+std::to_string(++temporary_counter);
+    new_base_name += "$0";
 
     new_symbol.base_name=new_base_name;
     new_symbol.mode=symbol.mode;
   }
 
   new_symbol.name=tmp_symbol_prefix+id2string(new_symbol.base_name);
 
+  // ensure that the name is unique
   new_name(new_symbol);
 
   {
@@ -429,10 +430,11 @@ void goto_convertt::remove_cpp_new(
 
   auxiliary_symbolt new_symbol;
 
-  new_symbol.base_name="new_ptr$"+std::to_string(++temporary_counter);
+  new_symbol.base_name = "new_ptr$0";
   new_symbol.type=expr.type();
   new_symbol.name=tmp_symbol_prefix+id2string(new_symbol.base_name);
 
+  // ensure that the name is unique
   new_name(new_symbol);
 
   code_declt decl;
@@ -480,11 +482,12 @@ void goto_convertt::remove_malloc(
   {
     auxiliary_symbolt new_symbol;
 
-    new_symbol.base_name="malloc_value$"+std::to_string(++temporary_counter);
+    new_symbol.base_name = "malloc_value$0";
     new_symbol.type=expr.type();
     new_symbol.name=tmp_symbol_prefix+id2string(new_symbol.base_name);
     new_symbol.location=expr.source_location();
 
+    // ensure that the name is unique
     new_name(new_symbol);
 
     code_declt decl;

src/goto-programs/remove_function_pointers.cpp

@@ -233,14 +233,13 @@ void remove_function_pointerst::fix_return_type(
        code_type.return_type(), ns))
     return;
 
-  symbolt &tmp_symbol=
-    get_fresh_aux_symbol(
-      code_type.return_type(),
-      "remove_function_pointers",
-      "tmp_return_val",
-      function_call.source_location(),
-      irep_idt(),
-      symbol_table);
+  symbolt &tmp_symbol = get_fresh_aux_symbol(
+    code_type.return_type(),
+    id2string(function_call.source_location().get_function()),
+    "tmp_return_val",
+    function_call.source_location(),
+    irep_idt(),
+    symbol_table);
 
   symbol_exprt tmp_symbol_expr;
   tmp_symbol_expr.type()=tmp_symbol.type;

src/goto-programs/remove_instanceof.cpp

@@ -106,14 +106,13 @@ std::size_t remove_instanceoft::lower_instanceof(
   symbol_typet jlo=to_symbol_type(java_lang_object_type().subtype());
   exprt object_clsid=get_class_identifier_field(check_ptr, jlo, ns);
 
-  symbolt &newsym=
-    get_fresh_aux_symbol(
-      object_clsid.type(),
-      "instanceof_tmp",
-      "instanceof_tmp",
-      source_locationt(),
-      ID_java,
-      symbol_table);
+  symbolt &newsym = get_fresh_aux_symbol(
+    object_clsid.type(),
+    id2string(this_inst->function),
+    "instanceof_tmp",
+    source_locationt(),
+    ID_java,
+    symbol_table);
 
   auto newinst=goto_program.insert_after(this_inst);
   newinst->make_assignment();

src/java_bytecode/java_entry_point.cpp

@@ -203,19 +203,21 @@ exprt::operandst java_build_arguments(
     bool allow_null=
       !assume_init_pointers_not_null && !is_main && !is_this;
 
+    object_factory_parameterst parameters = object_factory_parameters;
+    parameters.function_id = function.name;
+
     // generate code to allocate and non-deterministicaly initialize the
     // argument
-    main_arguments[param_number]=
-      object_factory(
-        p.type(),
-        base_name,
-        init_code,
-        allow_null,
-        symbol_table,
-        object_factory_parameters,
-        allocation_typet::LOCAL,
-        function.location,
-        pointer_type_selector);
+    main_arguments[param_number] = object_factory(
+      p.type(),
+      base_name,
+      init_code,
+      allow_null,
+      symbol_table,
+      parameters,
+      allocation_typet::LOCAL,
+      function.location,
+      pointer_type_selector);
 
     // record as an input
     codet input(ID_input);