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Handle array_{copy,replace,set} in dependence graph #6710

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Merged
merged 1 commit into from
Mar 9, 2022
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Handle array_{copy,replace,set} in dependence graph #6710

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9 changes: 9 additions & 0 deletions regression/cbmc/Bool5/full-slice.desc
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
CORE
main.c
--full-slice
Generated 4 VCC\(s\), 0 remaining after simplification
^VERIFICATION SUCCESSFUL$
^EXIT=0$
^SIGNAL=0$
--
^warning: ignoring
63 changes: 56 additions & 7 deletions src/analyses/goto_rw.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -621,6 +621,17 @@ void rw_range_sett::get_objects_rec(const typet &type)
}
}

void rw_range_sett::get_array_objects(
const irep_idt &,
goto_programt::const_targett,
get_modet mode,
const exprt &pointer)
{
object_descriptor_exprt ode;
ode.build(dereference_exprt{skip_typecast(pointer)}, ns);
get_objects_rec(mode, ode.root_object(), -1, -1);
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🪄 magic numbers?

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Fair point! These are used throughout goto_rw, so I'll post a follow-up PR that fix this throughout this piece of code.

}

void rw_range_set_value_sett::get_objects_dereference(
get_modet mode,
const dereference_exprt &deref,
Expand Down Expand Up @@ -737,6 +748,50 @@ static void goto_rw_assign(
rw_set.get_objects_rec(function, target, rw_range_sett::get_modet::READ, rhs);
}

static void goto_rw_other(
const irep_idt &function,
goto_programt::const_targett target,
const codet &code,
rw_range_sett &rw_set)
{
const irep_idt &statement = code.get_statement();

if(statement == ID_printf)
{
// if it's printf, mark the operands as read here
for(const auto &op : code.operands())
{
rw_set.get_objects_rec(
function, target, rw_range_sett::get_modet::READ, op);
}
}
else if(statement == ID_array_equal)
{
// mark the dereferenced operands as being read
for(const auto &op : code.operands())
{
rw_set.get_array_objects(
function, target, rw_range_sett::get_modet::READ, op);
}
}
else if(statement == ID_array_set)
{
PRECONDITION(code.operands().size() == 2);
rw_set.get_array_objects(
function, target, rw_range_sett::get_modet::LHS_W, code.op0());
rw_set.get_objects_rec(
function, target, rw_range_sett::get_modet::READ, code.op1());
}
else if(statement == ID_array_copy || statement == ID_array_replace)
{
PRECONDITION(code.operands().size() == 2);
rw_set.get_array_objects(
function, target, rw_range_sett::get_modet::LHS_W, code.op0());
rw_set.get_array_objects(
function, target, rw_range_sett::get_modet::READ, code.op1());
}
}

static void goto_rw(
const irep_idt &function,
goto_programt::const_targett target,
Expand Down Expand Up @@ -787,13 +842,7 @@ void goto_rw(
break;

case OTHER:
// if it's printf, mark the operands as read here
if(target->get_other().get_statement() == ID_printf)
{
for(const auto &op : target->get_other().operands())
rw_set.get_objects_rec(
function, target, rw_range_sett::get_modet::READ, op);
}
goto_rw_other(function, target, target->get_other(), rw_set);
break;

case SKIP:
Expand Down
18 changes: 18 additions & 0 deletions src/analyses/goto_rw.h
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Original file line number Diff line number Diff line change
Expand Up @@ -148,6 +148,12 @@ class rw_range_sett
get_objects_rec(type);
}

virtual void get_array_objects(
const irep_idt &,
goto_programt::const_targett,
get_modet,
const exprt &);

void output(std::ostream &out) const;

protected:
Expand Down Expand Up @@ -288,6 +294,18 @@ class rw_range_set_value_sett:public rw_range_sett
rw_range_sett::get_objects_rec(type);
}

void get_array_objects(
const irep_idt &_function,
goto_programt::const_targett _target,
get_modet mode,
const exprt &pointer) override
{
function = _function;
target = _target;

rw_range_sett::get_array_objects(_function, _target, mode, pointer);
}

protected:
value_setst &value_sets;
irep_idt function;
Expand Down
3 changes: 3 additions & 0 deletions src/analyses/reaching_definitions.cpp
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Expand Up @@ -126,6 +126,9 @@ void rd_range_domaint::transform(
// initial (non-deterministic) value
else if(from->is_decl())
transform_assign(ns, from, function_from, from, *rd);
// array_set, array_copy, array_replace have side effects
else if(from->is_other())
transform_assign(ns, from, function_from, from, *rd);
}

/// Computes an instance obtained from a `*this` by transformation over `DEAD v`
Expand Down