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Typedefs | Enumerations | Functions
java_object_factory.h File Reference

This module is responsible for the synthesis of code (in the form of a sequence of codet statements) that can allocate and initialize non-deterministically both primitive Java types and objects. More...

#include <util/std_code.h>
#include <ansi-c/allocate_objects.h>
#include "nondet.h"
+ Include dependency graph for java_object_factory.h:
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Go to the source code of this file.

Typedefs

using  array_element_generatort = std::function< code_blockt(const exprt &element_at_counter, const typet &element_type)>
 

Enumerations

enum class   update_in_placet { NO_UPDATE_IN_PLACE , MAY_UPDATE_IN_PLACE , MUST_UPDATE_IN_PLACE }
 

Functions

exprt  object_factory (const typet &type, const irep_idt base_name, code_blockt &init_code, symbol_table_baset &symbol_table, java_object_factory_parameterst parameters, lifetimet lifetime, const source_locationt &location, const select_pointer_typet &pointer_type_selector, message_handlert &log)
  Similar to gen_nondet_init below, but instead of allocating and non-deterministically initializing the the argument expr passed to that function, we create a static global object of type type and non-deterministically initialize it.
 
exprt  object_factory (const typet &type, const irep_idt base_name, code_blockt &init_code, symbol_table_baset &symbol_table, const java_object_factory_parameterst &object_factory_parameters, lifetimet lifetime, const source_locationt &location, message_handlert &log)
  Call object_factory() above with a default (identity) pointer_type_selector.
 
void  gen_nondet_init (const exprt &expr, code_blockt &init_code, symbol_table_baset &symbol_table, const source_locationt &loc, bool skip_classid, lifetimet lifetime, const java_object_factory_parameterst &object_factory_parameters, const select_pointer_typet &pointer_type_selector, update_in_placet update_in_place, message_handlert &log)
  Initializes a primitive-typed or reference-typed object tree rooted at expr, allocating child objects as necessary and nondet-initializing their members, or if MAY_ or MUST_UPDATE_IN_PLACE is set, re-initializing already-allocated objects.
 
void  gen_nondet_init (const exprt &expr, code_blockt &init_code, symbol_table_baset &symbol_table, const source_locationt &loc, bool skip_classid, lifetimet lifetime, const java_object_factory_parameterst &object_factory_parameters, update_in_placet update_in_place, message_handlert &log)
  Call gen_nondet_init() above with a default (identity) pointer_type_selector.
 
code_blockt  gen_nondet_array_init (const exprt &expr, update_in_placet update_in_place, const source_locationt &location, const array_element_generatort &element_generator, const allocate_local_symbolt &allocate_local_symbol, const symbol_table_baset &symbol_table, size_t max_nondet_array_length)
  Synthesize GOTO for generating a array of nondet length to be stored in the expr.
 

Detailed Description

This module is responsible for the synthesis of code (in the form of a sequence of codet statements) that can allocate and initialize non-deterministically both primitive Java types and objects.

The non-deterministic initialization of one object triggers the non-deterministic initialization of all its fields, which in turn could be references to other objects. We thus speak about an object tree.

This is useful for, e.g., the creation of a verification harness (non-det initialization of the parameters of the method to verify), mocking methods that are called but for which we don't have a body (overapproximating the return value and possibly side effects).

The two main APIs are gen_nondet_init() and object_factory() (which calls gen_nondet_init()), at the bottom of the file. A call to

gen_nondet_init(expr, code, ..., update_in_place)

appends to code (a code_blockt) a sequence of statements that non-deterministically initialize the expr (which is expected to be an l-value exprt) with a primitive or reference value of type equal to or compatible with expr.type() – see documentation for the argument pointer_type_selector for additional details. gen_nondet_init() is the starting point of a recursive algorithm, and most other functions in this file are different (recursive or base) cases depending on the type of expr.

The code generated mainly depends on the parameter update_in_place. Assume that expr is a reference to an object (in our IR, that means a pointer to a struct).

When update_in_place == NO_UPDATE_IN_PLACE, the following code is generated:

struct MyClass object;
if (NONDET(bool))
expr = NULL;
else
expr = &object;
... // non-det initialization of `object` in NO_UPDATE_IN_PLACE mode
ait supplies three of the four components needed: an abstract interpreter (in this case handling func...
Definition ai.h:566
ait()
Definition ai.h:569
@ NONDET
havocs the pointer to an nondet pointer

When update_in_place == MUST_UPDATE_IN_PLACE, the following code is generated (assuming that MyClass has fields "int x" and "OtherClass y"):

expr->x = NONDET(int);
expr->y = ... // non-det initialization in MUST_UPDATE_IN_PLACE mode

When update_in_place == MAY_UPDATE_IN_PLACE, the following code is generated:

if (NONDET(bool))
... // non-det initialization of `expr` in MUST_UPDATE_IN_PLACE
else
... // non-det initialization of `expr` in NO_UPDATE_IN_PLACE

Definition in file java_object_factory.h.

Typedef Documentation

◆  array_element_generatort

using array_element_generatort = std::function< code_blockt(const exprt &element_at_counter, const typet &element_type)>

Definition at line 136 of file java_object_factory.h.

Enumeration Type Documentation

◆  update_in_placet

enum class update_in_placet
strong
Enumerator
NO_UPDATE_IN_PLACE 
MAY_UPDATE_IN_PLACE 
MUST_UPDATE_IN_PLACE 

Definition at line 106 of file java_object_factory.h.

Function Documentation

◆  gen_nondet_array_init()

code_blockt gen_nondet_array_init ( const exprt &  expr,
update_in_placet  update_in_place,
const source_locationt &  location,
const array_element_generatort &  element_generator,
const allocate_local_symbolt &  allocate_local_symbol,
const symbol_table_baset &  symbol_table,
size_t  max_nondet_array_length 
)

Synthesize GOTO for generating a array of nondet length to be stored in the expr.

Parameters
expr The array expression to initialize.
update_in_place Should the code allow the solver the freedom to leave the array as is.
location Source location to use for all synthesized code.
element_generator A function that creates a new element and assigns it to the provided expression.
allocate_local_symbol A function that creates a local symbol in the symbol table. See java_object_factoryt::assign_element for an example implementation.
symbol_table The symbol table.
max_nondet_array_length The maximum size the array can be.
Returns
The GOTO that approximates:
array_length = NONDET(int)
ASSUME(array_length < max_nondet_array_length)
expr = java_new_array(max_nondet_array_length)
expr->length = array_length
for (int i = 0; i < array_length; ++i)
@ ASSUME
Definition goto_program.h:34

Definition at line 1372 of file java_object_factory.cpp.

◆  gen_nondet_init() [1/2]

void gen_nondet_init ( const exprt &  expr,
code_blockt &  init_code,
symbol_table_baset &  symbol_table,
const source_locationt &  loc,
bool  skip_classid,
lifetimet  lifetime,
const java_object_factory_parameterst &  object_factory_parameters,
const select_pointer_typet &  pointer_type_selector,
update_in_placet  update_in_place,
message_handlert &  log 
)

Initializes a primitive-typed or reference-typed object tree rooted at expr, allocating child objects as necessary and nondet-initializing their members, or if MAY_ or MUST_UPDATE_IN_PLACE is set, re-initializing already-allocated objects.

Parameters
expr Lvalue expression to initialize.
[out] init_code A code block where the initializing assignments will be appended to. It gets an instruction sequence to initialize or reinitialize expr and child objects it refers to.
symbol_table The symbol table, where new variables created as a result of emitting code to init_code will be inserted to. This includes any necessary temporaries, and if create_dyn_objs is false, any allocated objects.
loc Source location to which all generated code will be associated to.
skip_classid If true, skip initializing field @class_identifier.
lifetime Lifetime of the allocated objects (AUTOMATIC_LOCAL, STATIC_GLOBAL, or DYNAMIC)
object_factory_parameters Parameters for the generation of non deterministic objects.
pointer_type_selector The pointer_selector to use to resolve pointer types where required.
update_in_place NO_UPDATE_IN_PLACE: initialize expr from scratch MAY_UPDATE_IN_PLACE: generate a runtime nondet branch between the NO_ and MUST_ cases. MUST_UPDATE_IN_PLACE: reinitialize an existing object
log used to report object construction warnings and failures

Definition at line 1621 of file java_object_factory.cpp.

◆  gen_nondet_init() [2/2]

void gen_nondet_init ( const exprt &  expr,
code_blockt &  init_code,
symbol_table_baset &  symbol_table,
const source_locationt &  loc,
bool  skip_classid,
lifetimet  lifetime,
const java_object_factory_parameterst &  object_factory_parameters,
update_in_placet  update_in_place,
message_handlert &  log 
)

Call gen_nondet_init() above with a default (identity) pointer_type_selector.

Definition at line 1678 of file java_object_factory.cpp.

◆  object_factory() [1/2]

exprt object_factory ( const typet &  type,
const irep_idt  base_name,
code_blockt &  init_code,
symbol_table_baset &  symbol_table,
const java_object_factory_parameterst &  object_factory_parameters,
lifetimet  lifetime,
const source_locationt &  location,
message_handlert &  log 
)

Call object_factory() above with a default (identity) pointer_type_selector.

Definition at line 1654 of file java_object_factory.cpp.

◆  object_factory() [2/2]

exprt object_factory ( const typet &  type,
const irep_idt  base_name,
code_blockt &  init_code,
symbol_table_baset &  symbol_table,
java_object_factory_parameterst  parameters,
lifetimet  lifetime,
const source_locationt &  loc,
const select_pointer_typet &  pointer_type_selector,
message_handlert &  log 
)

Similar to gen_nondet_init below, but instead of allocating and non-deterministically initializing the the argument expr passed to that function, we create a static global object of type type and non-deterministically initialize it.

See gen_nondet_init for a description of the parameters. The only new one is type, which is the type of the object to create.

Returns
The object created, the symbol_table gains any new symbols created, and init_code gains any instructions required to initialize either the returned value or its child objects

Definition at line 1544 of file java_object_factory.cpp.

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