CBMC
code_contractst Class Reference

#include <contracts.h>

+ Collaboration diagram for code_contractst:

Public Member Functions

 code_contractst (goto_modelt &goto_model, messaget &log, const loop_contract_configt &loop_contract_config)
 
void check_all_functions_found (const std::set< std::string > &functions) const
 Throws an exception if some function functions is found in the program. More...
 
void replace_calls (const std::set< std::string > &to_replace)
 Replace all calls to each function in the to_replace set with that function's contract. More...
 
void enforce_contracts (const std::set< std::string > &to_enforce, const std::set< std::string > &to_exclude_from_nondet_init={})
 Turn requires & ensures into assumptions and assertions for each of the named functions. More...
 
void apply_loop_contracts (const std::set< std::string > &to_exclude_from_nondet_init={})
 Applies loop contract transformations. More...
 
void check_apply_loop_contracts (const irep_idt &function_name, goto_functionst::goto_functiont &goto_function, const local_may_aliast &local_may_alias, goto_programt::targett loop_head, goto_programt::targett loop_end, const loopt &loop, exprt assigns_clause, exprt invariant, exprt decreases_clause, const irep_idt &mode)
 
std::unordered_map< goto_programt::const_targett, unsigned, const_target_hashget_original_loop_number_map () const
 
std::unordered_set< goto_programt::const_targett, const_target_hashget_loop_havoc_set () const
 
void enforce_contract (const irep_idt &function)
 Enforce contract of a single function. More...
 
void check_frame_conditions_function (const irep_idt &function)
 Instrument functions to check frame conditions. More...
 
void apply_loop_contract (const irep_idt &function, goto_functionst::goto_functiont &goto_function)
 Apply loop contracts, whenever available, to all loops in function. More...
 
void apply_function_contract (const irep_idt &function, const source_locationt &location, goto_programt &function_body, goto_programt::targett &target)
 Replaces function calls with assertions based on requires clauses, non-deterministic assignments for the write set, and assumptions based on ensures clauses. More...
 
void add_contract_check (const irep_idt &wrapper_function, const irep_idt &mangled_function, goto_programt &dest)
 Instruments wrapper_function adding assumptions based on requires clauses and assertions based on ensures clauses. More...
 

Public Attributes

const namespacet ns
 

Protected Attributes

goto_modeltgoto_model
 
symbol_tabletsymbol_table
 
goto_functionstgoto_functions
 
messagetlog
 
std::unordered_set< irep_idtsummarized
 
std::list< std::string > loop_names
 Name of loops we are going to unwind. More...
 
std::unordered_map< goto_programt::const_targett, unsigned, const_target_hashoriginal_loop_number_map
 Store the map from instrumented instructions for loop contracts to their original loop numbers. More...
 
std::unordered_set< goto_programt::const_targett, const_target_hashloop_havoc_set
 Loop havoc instructions instrumented during applying loop contracts. More...
 
loop_contract_configt loop_contract_config
 

Detailed Description

Definition at line 62 of file contracts.h.

Constructor & Destructor Documentation

◆ code_contractst()

code_contractst::code_contractst ( goto_modelt goto_model,
messaget log,
const loop_contract_configt loop_contract_config 
)
inline

Definition at line 65 of file contracts.h.

Member Function Documentation

◆ add_contract_check()

void code_contractst::add_contract_check ( const irep_idt wrapper_function,
const irep_idt mangled_function,
goto_programt dest 
)

Instruments wrapper_function adding assumptions based on requires clauses and assertions based on ensures clauses.

Definition at line 1269 of file contracts.cpp.

◆ apply_function_contract()

void code_contractst::apply_function_contract ( const irep_idt function,
const source_locationt location,
goto_programt function_body,
goto_programt::targett target 
)

Replaces function calls with assertions based on requires clauses, non-deterministic assignments for the write set, and assumptions based on ensures clauses.

Definition at line 609 of file contracts.cpp.

◆ apply_loop_contract()

void code_contractst::apply_loop_contract ( const irep_idt function,
goto_functionst::goto_functiont goto_function 
)

Apply loop contracts, whenever available, to all loops in function.

Loop invariants, loop variants, and loop assigns clauses.

Definition at line 836 of file contracts.cpp.

◆ apply_loop_contracts()

void code_contractst::apply_loop_contracts ( const std::set< std::string > &  to_exclude_from_nondet_init = {})

Applies loop contract transformations.

Static variables of the model are nondet-initialized, except for the ones specified in to_exclude_from_nondet_init.

Definition at line 1482 of file contracts.cpp.

◆ check_all_functions_found()

void code_contractst::check_all_functions_found ( const std::set< std::string > &  functions) const

Throws an exception if some function functions is found in the program.

Definition at line 1427 of file contracts.cpp.

◆ check_apply_loop_contracts()

void code_contractst::check_apply_loop_contracts ( const irep_idt function_name,
goto_functionst::goto_functiont goto_function,
const local_may_aliast local_may_alias,
goto_programt::targett  loop_head,
goto_programt::targett  loop_end,
const loopt loop,
exprt  assigns_clause,
exprt  invariant,
exprt  decreases_clause,
const irep_idt mode 
)

Definition at line 49 of file contracts.cpp.

◆ check_frame_conditions_function()

void code_contractst::check_frame_conditions_function ( const irep_idt function)

Instrument functions to check frame conditions.

Definition at line 1122 of file contracts.cpp.

◆ enforce_contract()

void code_contractst::enforce_contract ( const irep_idt function)

Enforce contract of a single function.

Definition at line 1213 of file contracts.cpp.

◆ enforce_contracts()

void code_contractst::enforce_contracts ( const std::set< std::string > &  to_enforce,
const std::set< std::string > &  to_exclude_from_nondet_init = {} 
)

Turn requires & ensures into assumptions and assertions for each of the named functions.

Throws an exception if some to_enforce functions are not found.

Use this function to prove the correctness of a function F independently of its calling context. If you have proved that F is correct, then you can soundly replace all calls to F with F's contract using the code_contractst::replace_calls() function; this means that symbolic execution does not need to explore F every time it is called, increasing scalability.

Static variables of the model are nondet-initialized, except for the ones specified in to_exclude_from_nondet_init.

Implementation: mangle the name of each function F into a new name, __CPROVER_contracts_original_F (CF for short). Then mint a new function called F that assumes CF's requires clause, calls CF, and then asserts CF's ensures clause.

Definition at line 1563 of file contracts.cpp.

◆ get_loop_havoc_set()

std::unordered_set<goto_programt::const_targett, const_target_hash> code_contractst::get_loop_havoc_set ( ) const
inline

Definition at line 145 of file contracts.h.

◆ get_original_loop_number_map()

std::unordered_map<goto_programt::const_targett, unsigned, const_target_hash> code_contractst::get_original_loop_number_map ( ) const
inline

Definition at line 139 of file contracts.h.

◆ replace_calls()

void code_contractst::replace_calls ( const std::set< std::string > &  to_replace)

Replace all calls to each function in the to_replace set with that function's contract.

Throws an exception if some to_replace functions are not found.

Use this function when proving code that calls into an expensive function, F. You can write a contract for F using __CPROVER_requires and __CPROVER_ensures, and then use this function to replace all calls to F with an assertion that the requires clause holds followed by an assumption that the ensures clause holds. In order to ensure that F actually abides by its ensures and requires clauses, you should separately call code_contractst::enforce_contracts() on F and verify it using cbmc --function F.

Definition at line 1442 of file contracts.cpp.

Member Data Documentation

◆ goto_functions

goto_functionst& code_contractst::goto_functions
protected

Definition at line 155 of file contracts.h.

◆ goto_model

goto_modelt& code_contractst::goto_model
protected

Definition at line 153 of file contracts.h.

◆ log

messaget& code_contractst::log
protected

Definition at line 157 of file contracts.h.

◆ loop_contract_config

loop_contract_configt code_contractst::loop_contract_config
protected

Definition at line 176 of file contracts.h.

◆ loop_havoc_set

std::unordered_set<goto_programt::const_targett, const_target_hash> code_contractst::loop_havoc_set
protected

Loop havoc instructions instrumented during applying loop contracts.

Definition at line 173 of file contracts.h.

◆ loop_names

std::list<std::string> code_contractst::loop_names
protected

Name of loops we are going to unwind.

Definition at line 162 of file contracts.h.

◆ ns

const namespacet code_contractst::ns

Definition at line 150 of file contracts.h.

◆ original_loop_number_map

std::unordered_map<goto_programt::const_targett, unsigned, const_target_hash> code_contractst::original_loop_number_map
protected

Store the map from instrumented instructions for loop contracts to their original loop numbers.

Following instrumented instructions are stored.

  1. loop-havoc — begin of transformed loops
  2. ASSIGN ENTERED_LOOP = TRUE — end of transformed loops

Definition at line 169 of file contracts.h.

◆ summarized

std::unordered_set<irep_idt> code_contractst::summarized
protected

Definition at line 159 of file contracts.h.

◆ symbol_table

symbol_tablet& code_contractst::symbol_table
protected

Definition at line 154 of file contracts.h.


The documentation for this class was generated from the following files: