cprover
label_function_pointer_call_sites.cpp
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1 /*******************************************************************\
2 Module: Label function pointer call sites
3 Author: Diffblue Ltd.
4 \*******************************************************************/
5 
8 
10 
11 #include <util/pointer_expr.h>
12 
13 #include "goto_model.h"
14 
16 {
17  for(auto &goto_function : goto_model.goto_functions.function_map)
18  {
19  std::size_t function_pointer_call_counter = 0;
20 
22  goto_function.second,
23  [](const goto_programt::targett it) {
24  return it->is_function_call() &&
25  can_cast_expr<dereference_exprt>(it->call_function());
26  },
27  [&](goto_programt::targett &it) {
28  auto const &function_pointer_dereference =
29  to_dereference_expr(it->call_function());
30  auto const &source_location = it->source_location;
31  auto const &goto_function_symbol_mode =
32  goto_model.symbol_table.lookup_ref(goto_function.first).mode;
33 
34  auto const call_site_symbol_name =
35  irep_idt{id2string(goto_function.first) + ".function_pointer_call." +
36  std::to_string(++function_pointer_call_counter)};
37 
38  // insert new function pointer variable into the symbol table
39  goto_model.symbol_table.insert([&] {
40  symbolt function_call_site_symbol{};
41  function_call_site_symbol.name = function_call_site_symbol.base_name =
42  function_call_site_symbol.pretty_name = call_site_symbol_name;
43  function_call_site_symbol.type =
44  function_pointer_dereference.pointer().type();
45  function_call_site_symbol.location = it->source_location;
46  function_call_site_symbol.is_lvalue = true;
47  function_call_site_symbol.mode = goto_function_symbol_mode;
48  return function_call_site_symbol;
49  }());
50 
51  auto const new_function_pointer =
52  goto_model.symbol_table.lookup_ref(call_site_symbol_name)
53  .symbol_expr();
54 
55  // add assignment to the new function pointer variable, followed by a
56  // call of the new variable
57  auto assign_instruction = goto_programt::make_assignment(
58  code_assignt{new_function_pointer,
59  function_pointer_dereference.pointer()},
60  source_location);
61 
62  goto_function.second.body.insert_before_swap(it, assign_instruction);
63  const auto next = std::next(it);
64  to_code_function_call(next->code_nonconst()).function() =
65  dereference_exprt{new_function_pointer};
66  // we need to increment the iterator once more (in addition to the
67  // increment already done by for_each_goto_function_if()). This is
68  // because insert_before_swap() inserts a new instruction after the
69  // instruction pointed to by it (and then swaps the contents with the
70  // previous instruction). We need to increment the iterator as we also
71  // need to skip over this newly inserted instruction.
72  it++;
73  });
74  }
75 }
A codet representing an assignment in the program.
Definition: std_code.h:293
exprt & function()
Definition: std_code.h:1248
Operator to dereference a pointer.
Definition: pointer_expr.h:628
function_mapt function_map
symbol_tablet symbol_table
Symbol table.
Definition: goto_model.h:30
goto_functionst goto_functions
GOTO functions.
Definition: goto_model.h:33
instructionst::iterator targett
Definition: goto_program.h:646
static instructiont make_assignment(const code_assignt &_code, const source_locationt &l=source_locationt::nil())
Create an assignment instruction.
const symbolt & lookup_ref(const irep_idt &name) const
Find a symbol in the symbol table for read-only access.
virtual std::pair< symbolt &, bool > insert(symbolt symbol) override
Author: Diffblue Ltd.
class symbol_exprt symbol_expr() const
Produces a symbol_exprt for a symbol.
Definition: symbol.cpp:121
Symbol Table + CFG.
void for_each_instruction_if(GotoFunctionT &&goto_function, PredicateT predicate, HandlerT handler)
void label_function_pointer_call_sites(goto_modelt &goto_model)
This ensures that call instructions can be only one of two things:
Label function pointer call sites across a goto model.
API to expression classes for Pointers.
const code_function_callt & to_code_function_call(const codet &code)
Definition: std_code.h:1324