cprover
Public Types | Public Member Functions | Public Attributes | Static Public Attributes | List of all members
goto_programt::instructiont Class Referencefinal

This class represents an instruction in the GOTO intermediate representation. More...

#include <goto_program.h>

+ Collaboration diagram for goto_programt::instructiont:

Public Types

typedef std::list< instructiont >::iterator targett
 The target for gotos and for start_thread nodes. More...
 
typedef std::list< instructiont >::const_iterator const_targett
 
typedef std::list< targett > targetst
 
typedef std::list< const_targett > const_targetst
 
typedef std::list< irep_idt > labelst
 Goto target labels. More...
 

Public Member Functions

targett get_target () const
 Returns the first (and only) successor for the usual case of a single target. More...
 
void set_target (targett t)
 Sets the first (and only) successor for the usual case of a single target. More...
 
bool has_target () const
 
bool is_target () const
 Is this node a branch target? More...
 
void clear (goto_program_instruction_typet _type)
 Clear the node. More...
 
void make_return ()
 
void make_skip ()
 
void make_location (const source_locationt &l)
 
void make_throw ()
 
void make_catch ()
 
void make_assertion (const exprt &g)
 
void make_assumption (const exprt &g)
 
void make_assignment ()
 
void make_other (const codet &_code)
 
void make_decl ()
 
void make_dead ()
 
void make_atomic_begin ()
 
void make_atomic_end ()
 
void make_end_function ()
 
void make_incomplete_goto (const code_gotot &_code)
 
void make_goto (targett _target)
 
void make_goto (targett _target, const exprt &g)
 
void complete_goto (targett _target)
 
void make_assignment (const codet &_code)
 
void make_decl (const codet &_code)
 
void make_function_call (const codet &_code)
 
bool is_goto () const
 
bool is_return () const
 
bool is_assign () const
 
bool is_function_call () const
 
bool is_throw () const
 
bool is_catch () const
 
bool is_skip () const
 
bool is_location () const
 
bool is_other () const
 
bool is_decl () const
 
bool is_dead () const
 
bool is_assume () const
 
bool is_assert () const
 
bool is_atomic_begin () const
 
bool is_atomic_end () const
 
bool is_start_thread () const
 
bool is_end_thread () const
 
bool is_end_function () const
 
bool is_incomplete_goto () const
 
 instructiont ()
 
 instructiont (goto_program_instruction_typet _type)
 
void swap (instructiont &instruction)
 Swap two instructions. More...
 
bool is_backwards_goto () const
 Returns true if the instruction is a backwards branch. More...
 
std::string to_string () const
 
bool equals (const instructiont &other) const
 Syntactic equality: two instructiont are equal if they have the same type, code, guard, number of targets, and labels. More...
 
void validate (const namespacet &ns, const validation_modet vm) const
 Check that the instruction is well-formed. More...
 

Public Attributes

codet code
 
irep_idt function
 The function this instruction belongs to. More...
 
source_locationt source_location
 The location of the instruction in the source file. More...
 
goto_program_instruction_typet type
 What kind of instruction? More...
 
exprt guard
 Guard for gotos, assume, assert. More...
 
targetst targets
 The list of successor instructions. More...
 
labelst labels
 
std::set< targett > incoming_edges
 
unsigned location_number
 A globally unique number to identify a program location. More...
 
unsigned loop_number
 Number unique per function to identify loops. More...
 
unsigned target_number
 A number to identify branch targets. More...
 

Static Public Attributes

static const unsigned nil_target
 Uniquely identify an invalid target or location. More...
 

Detailed Description

This class represents an instruction in the GOTO intermediate representation.

Three fields are key:

  • type: an enum value describing the action performed by this instruction
  • guard: an (arbitrarily complex) expression (usually an exprt) of Boolean type
  • code: a code statement (usually a codet)

The meaning of an instruction node depends on the type field. Different kinds of instructions make use of the fields guard and code for different purposes. We list below, using a mixture of pseudo code and plain English, the meaning of different kinds of instructions. We use guard, code, and targets to mean the value of the respective fields in this class:

  • GOTO: goto targets if and only if guard is true. More than one target is deprecated. Its semantics was a non-deterministic choice.
  • RETURN: Set the value returned by code (which shall be either nil or an instance of code_returnt) and then jump to the end of the function. Many analysis tools remove these instructions before they start.
  • DECL: Introduces a symbol denoted by the field code (an instance of code_declt), the life-time of which is bounded by a corresponding DEAD instruction. Non-static symbols must be DECL'd before they are used.
  • DEAD: Ends the life of the symbol denoted by the field code. After a DEAD instruction the symbol must be DECL'd again before use.
  • FUNCTION_CALL: Invoke the function denoted by field code (an instance of code_function_callt).
  • ASSIGN: Update the left-hand side of code (an instance of code_assignt) to the value of the right-hand side.
  • OTHER: Execute the code (an instance of codet of kind ID_fence, ID_printf, ID_array_copy, ID_array_set, ID_input, ID_output, ...).
  • ASSUME: This thread of execution waits for guard to evaluate to true. Assume does not "retro-actively" affect the thread or any ASSERTs.
  • ASSERT: Using ASSERT instructions is the one and only way to express properties to be verified. An assertion is true / safe if guard is true in all possible executions, otherwise it is false / unsafe. The status of the assertion does not affect execution in any way.
  • SKIP, LOCATION: No-op.
  • ATOMIC_BEGIN, ATOMIC_END: When a thread executes ATOMIC_BEGIN, no thread other will be able to execute any instruction until the same thread executes ATOMIC_END. Concurrency is not supported by all analysis tools.
  • END_FUNCTION: Must occur as the last instruction of the list and nowhere else.
  • START_THREAD: Create a new thread and run the code of this function starting from targets[0]. Quite often the instruction pointed by targets[0] will be just a FUNCTION_CALL, followed by an END_THREAD. Concurrency is not supported by all analysis tools.
  • END_THREAD: Terminate the calling thread. Concurrency is not supported by all analysis tools.
  • THROW: throw exception1, ..., exceptionN where the list of exceptions is extracted from the code field Many analysis tools remove these instructions before they start.
  • CATCH, when code.find(ID_exception_list) is non-empty: Establishes that from here to the next occurrence of CATCH with an empty list (see below) if
    • exception1 is thrown, then goto target1,
    • ...
    • exceptionN is thrown, then goto targetN. The list of exceptions is obtained from the code field and the list of targets from the targets field.
  • CATCH, when empty code.find(ID_exception_list) is empty: clears all the catch clauses established as per the above in this function? Many analysis tools remove these instructions before they start.
  • INCOMPLETE GOTO: goto for which the target is yet to be determined. The target set shall be empty

Definition at line 178 of file goto_program.h.

Member Typedef Documentation

◆ const_targetst

typedef std::list<const_targett> goto_programt::instructiont::const_targetst

Definition at line 200 of file goto_program.h.

◆ const_targett

typedef std::list<instructiont>::const_iterator goto_programt::instructiont::const_targett

Definition at line 198 of file goto_program.h.

◆ labelst

typedef std::list<irep_idt> goto_programt::instructiont::labelst

Goto target labels.

Definition at line 227 of file goto_program.h.

◆ targetst

typedef std::list<targett> goto_programt::instructiont::targetst

Definition at line 199 of file goto_program.h.

◆ targett

typedef std::list<instructiont>::iterator goto_programt::instructiont::targett

The target for gotos and for start_thread nodes.

Definition at line 197 of file goto_program.h.

Constructor & Destructor Documentation

◆ instructiont() [1/2]

goto_programt::instructiont::instructiont ( )
inline

Definition at line 328 of file goto_program.h.

◆ instructiont() [2/2]

goto_programt::instructiont::instructiont ( goto_program_instruction_typet  _type)
inlineexplicit

Definition at line 333 of file goto_program.h.

Member Function Documentation

◆ clear()

void goto_programt::instructiont::clear ( goto_program_instruction_typet  _type)
inline

Clear the node.

Definition at line 238 of file goto_program.h.

◆ complete_goto()

void goto_programt::instructiont::complete_goto ( targett  _target)
inline

Definition at line 280 of file goto_program.h.

◆ equals()

bool goto_programt::instructiont::equals ( const instructiont &  other) const

Syntactic equality: two instructiont are equal if they have the same type, code, guard, number of targets, and labels.

All other members can only be evaluated in the context of a goto_programt (see goto_programt::equals).

Definition at line 660 of file goto_program.cpp.

◆ get_target()

targett goto_programt::instructiont::get_target ( ) const
inline

Returns the first (and only) successor for the usual case of a single target.

Definition at line 207 of file goto_program.h.

◆ has_target()

bool goto_programt::instructiont::has_target ( ) const
inline

Definition at line 221 of file goto_program.h.

◆ is_assert()

bool goto_programt::instructiont::is_assert ( ) const
inline

Definition at line 317 of file goto_program.h.

◆ is_assign()

bool goto_programt::instructiont::is_assign ( ) const
inline

Definition at line 307 of file goto_program.h.

◆ is_assume()

bool goto_programt::instructiont::is_assume ( ) const
inline

Definition at line 316 of file goto_program.h.

◆ is_atomic_begin()

bool goto_programt::instructiont::is_atomic_begin ( ) const
inline

Definition at line 318 of file goto_program.h.

◆ is_atomic_end()

bool goto_programt::instructiont::is_atomic_end ( ) const
inline

Definition at line 319 of file goto_program.h.

◆ is_backwards_goto()

bool goto_programt::instructiont::is_backwards_goto ( ) const
inline

Returns true if the instruction is a backwards branch.

Definition at line 379 of file goto_program.h.

◆ is_catch()

bool goto_programt::instructiont::is_catch ( ) const
inline

Definition at line 310 of file goto_program.h.

◆ is_dead()

bool goto_programt::instructiont::is_dead ( ) const
inline

Definition at line 315 of file goto_program.h.

◆ is_decl()

bool goto_programt::instructiont::is_decl ( ) const
inline

Definition at line 314 of file goto_program.h.

◆ is_end_function()

bool goto_programt::instructiont::is_end_function ( ) const
inline

Definition at line 322 of file goto_program.h.

◆ is_end_thread()

bool goto_programt::instructiont::is_end_thread ( ) const
inline

Definition at line 321 of file goto_program.h.

◆ is_function_call()

bool goto_programt::instructiont::is_function_call ( ) const
inline

Definition at line 308 of file goto_program.h.

◆ is_goto()

bool goto_programt::instructiont::is_goto ( ) const
inline

Definition at line 305 of file goto_program.h.

◆ is_incomplete_goto()

bool goto_programt::instructiont::is_incomplete_goto ( ) const
inline

Definition at line 323 of file goto_program.h.

◆ is_location()

bool goto_programt::instructiont::is_location ( ) const
inline

Definition at line 312 of file goto_program.h.

◆ is_other()

bool goto_programt::instructiont::is_other ( ) const
inline

Definition at line 313 of file goto_program.h.

◆ is_return()

bool goto_programt::instructiont::is_return ( ) const
inline

Definition at line 306 of file goto_program.h.

◆ is_skip()

bool goto_programt::instructiont::is_skip ( ) const
inline

Definition at line 311 of file goto_program.h.

◆ is_start_thread()

bool goto_programt::instructiont::is_start_thread ( ) const
inline

Definition at line 320 of file goto_program.h.

◆ is_target()

bool goto_programt::instructiont::is_target ( ) const
inline

Is this node a branch target?

Definition at line 234 of file goto_program.h.

◆ is_throw()

bool goto_programt::instructiont::is_throw ( ) const
inline

Definition at line 309 of file goto_program.h.

◆ make_assertion()

void goto_programt::instructiont::make_assertion ( const exprt &  g)
inline

Definition at line 252 of file goto_program.h.

◆ make_assignment() [1/2]

void goto_programt::instructiont::make_assignment ( )
inline

Definition at line 254 of file goto_program.h.

◆ make_assignment() [2/2]

void goto_programt::instructiont::make_assignment ( const codet &  _code)
inline

Definition at line 287 of file goto_program.h.

◆ make_assumption()

void goto_programt::instructiont::make_assumption ( const exprt &  g)
inline

Definition at line 253 of file goto_program.h.

◆ make_atomic_begin()

void goto_programt::instructiont::make_atomic_begin ( )
inline

Definition at line 258 of file goto_program.h.

◆ make_atomic_end()

void goto_programt::instructiont::make_atomic_end ( )
inline

Definition at line 259 of file goto_program.h.

◆ make_catch()

void goto_programt::instructiont::make_catch ( )
inline

Definition at line 251 of file goto_program.h.

◆ make_dead()

void goto_programt::instructiont::make_dead ( )
inline

Definition at line 257 of file goto_program.h.

◆ make_decl() [1/2]

void goto_programt::instructiont::make_decl ( )
inline

Definition at line 256 of file goto_program.h.

◆ make_decl() [2/2]

void goto_programt::instructiont::make_decl ( const codet &  _code)
inline

Definition at line 293 of file goto_program.h.

◆ make_end_function()

void goto_programt::instructiont::make_end_function ( )
inline

Definition at line 260 of file goto_program.h.

◆ make_function_call()

void goto_programt::instructiont::make_function_call ( const codet &  _code)
inline

Definition at line 299 of file goto_program.h.

◆ make_goto() [1/2]

void goto_programt::instructiont::make_goto ( targett  _target)
inline

Definition at line 268 of file goto_program.h.

◆ make_goto() [2/2]

void goto_programt::instructiont::make_goto ( targett  _target,
const exprt &  g 
)
inline

Definition at line 274 of file goto_program.h.

◆ make_incomplete_goto()

void goto_programt::instructiont::make_incomplete_goto ( const code_gotot &  _code)
inline

Definition at line 262 of file goto_program.h.

◆ make_location()

void goto_programt::instructiont::make_location ( const source_locationt &  l)
inline

Definition at line 248 of file goto_program.h.

◆ make_other()

void goto_programt::instructiont::make_other ( const codet &  _code)
inline

Definition at line 255 of file goto_program.h.

◆ make_return()

void goto_programt::instructiont::make_return ( )
inline

Definition at line 246 of file goto_program.h.

◆ make_skip()

void goto_programt::instructiont::make_skip ( )
inline

Definition at line 247 of file goto_program.h.

◆ make_throw()

void goto_programt::instructiont::make_throw ( )
inline

Definition at line 250 of file goto_program.h.

◆ set_target()

void goto_programt::instructiont::set_target ( targett  t)
inline

Sets the first (and only) successor for the usual case of a single target.

Definition at line 215 of file goto_program.h.

◆ swap()

void goto_programt::instructiont::swap ( instructiont &  instruction)
inline

Swap two instructions.

Definition at line 344 of file goto_program.h.

◆ to_string()

std::string goto_programt::instructiont::to_string ( ) const
inline

Definition at line 391 of file goto_program.h.

◆ validate()

void goto_programt::instructiont::validate ( const namespacet &  ns,
const validation_modet  vm 
) const

Check that the instruction is well-formed.

The validation mode indicates whether well-formedness check failures are reported via DATA_INVARIANT violations or exceptions.

Definition at line 672 of file goto_program.cpp.

Member Data Documentation

◆ code

codet goto_programt::instructiont::code

Definition at line 181 of file goto_program.h.

◆ function

irep_idt goto_programt::instructiont::function

The function this instruction belongs to.

Definition at line 184 of file goto_program.h.

◆ guard

exprt goto_programt::instructiont::guard

Guard for gotos, assume, assert.

Definition at line 193 of file goto_program.h.

◆ incoming_edges

std::set<targett> goto_programt::instructiont::incoming_edges

Definition at line 231 of file goto_program.h.

◆ labels

labelst goto_programt::instructiont::labels

Definition at line 228 of file goto_program.h.

◆ location_number

unsigned goto_programt::instructiont::location_number

A globally unique number to identify a program location.

It's guaranteed to be ordered in program order within one goto_program.

Definition at line 369 of file goto_program.h.

◆ loop_number

unsigned goto_programt::instructiont::loop_number

Number unique per function to identify loops.

Definition at line 372 of file goto_program.h.

◆ nil_target

const unsigned goto_programt::instructiont::nil_target
static
Initial value:
=
std::numeric_limits<unsigned>::max()

Uniquely identify an invalid target or location.

Definition at line 362 of file goto_program.h.

◆ source_location

source_locationt goto_programt::instructiont::source_location

The location of the instruction in the source file.

Definition at line 187 of file goto_program.h.

◆ target_number

unsigned goto_programt::instructiont::target_number

A number to identify branch targets.

This is nil_target if it's not a target.

Definition at line 376 of file goto_program.h.

◆ targets

targetst goto_programt::instructiont::targets

The list of successor instructions.

Definition at line 203 of file goto_program.h.

◆ type

goto_program_instruction_typet goto_programt::instructiont::type

What kind of instruction?

Definition at line 190 of file goto_program.h.

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