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modernize loops in slice_by_trace #3849

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Jan 19, 2019
Merged

modernize loops in slice_by_trace #3849

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107 changes: 43 additions & 64 deletions src/goto-symex/slice_by_trace.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -55,31 +55,15 @@ void symex_slice_by_tracet::slice_by_trace(
idx=next;
}

exprt trace_condition;

if(trace_conditions.size()==1)
{
trace_condition=trace_conditions[0];
}
else
{
trace_condition=exprt(ID_and, typet(ID_bool));
trace_condition.operands().reserve(trace_conditions.size());
for(std::vector<exprt>::iterator i=trace_conditions.begin();
i!=trace_conditions.end(); i++)
{
trace_condition.move_to_operands(*i);
}
}
exprt trace_condition = conjunction(trace_conditions);

simplify(trace_condition, ns);

std::set<exprt> implications=implied_guards(trace_condition);

for(std::set<exprt>::iterator i=sliced_guards.begin(); i !=
sliced_guards.end(); i++)
for(const auto &guard : sliced_guards)
{
exprt g_copy(*i);
exprt g_copy(guard);

DATA_INVARIANT(
g_copy.id() == ID_symbol || g_copy.id() == ID_not ||
Expand Down Expand Up @@ -300,27 +284,29 @@ void symex_slice_by_tracet::compute_ts_back(
{
std::list<exprt> eq_conds;
std::list<exprt>::iterator pvi=i->io_args.begin();
for(std::vector<irep_idt>::iterator k=sigma_vals[j].begin();
k!=sigma_vals[j].end(); k++)

for(const auto &sigma_val : sigma_vals[j])
{
exprt equal_cond=exprt(ID_equal, bool_typet());
equal_cond.operands().reserve(2);
equal_cond.copy_to_operands(*pvi);
// Should eventually change to handle non-bv types!
exprt constant_value=
from_integer(unsafe_string2int(id2string(*k)), (*pvi).type());
exprt constant_value = from_integer(
unsafe_string2int(id2string(sigma_val)), (*pvi).type());
equal_cond.move_to_operands(constant_value);
eq_conds.push_back(equal_cond);
pvi++;
}

exprt val_merge=exprt(ID_and, typet(ID_bool));
val_merge.operands().reserve(eq_conds.size()+1);
val_merge.copy_to_operands(merge[j+1]);
for(std::list<exprt>::iterator k=eq_conds.begin();
k!= eq_conds.end(); k++)

for(const auto &eq_cond : eq_conds)
{
val_merge.copy_to_operands(*k);
val_merge.copy_to_operands(eq_cond);
}

u_lhs.move_to_operands(val_merge);
}
else
Expand Down Expand Up @@ -384,23 +370,20 @@ void symex_slice_by_tracet::slice_SSA_steps(
size_t location_SSA_steps=0;
size_t trace_loc_sliced=0;

for(symex_target_equationt::SSA_stepst::iterator
it=equation.SSA_steps.begin();
it!=equation.SSA_steps.end();
it++)
for(auto &SSA_step : equation.SSA_steps)
{
if(it->is_output())
if(SSA_step.is_output())
trace_SSA_steps++;
if(it->is_location())
if(SSA_step.is_location())
location_SSA_steps++;
bool sliced_SSA_step=false;
exprt guard=it->guard;
exprt guard = SSA_step.guard;

simplify(guard, ns);

if(!guard.is_true())
potential_SSA_steps++;
// it->output(ns,std::cout);
// SSA_step.output(ns,std::cout);
// std::cout << "-----------------\n";

if((guard.id()==ID_symbol) || (guard.id() == ID_not))
Expand All @@ -409,11 +392,11 @@ void symex_slice_by_tracet::slice_SSA_steps(

if(implications.count(guard)!=0)
{
it->cond_expr=true_exprt();
it->ssa_rhs=true_exprt();
it->guard=false_exprt();
SSA_step.cond_expr = true_exprt();
SSA_step.ssa_rhs = true_exprt();
SSA_step.guard = false_exprt();
sliced_SSA_steps++;
if(it->is_output() || it->is_location())
if(SSA_step.is_output() || SSA_step.is_location())
trace_loc_sliced++;
sliced_SSA_step=true;
}
Expand All @@ -427,11 +410,11 @@ void symex_slice_by_tracet::slice_SSA_steps(

if(implications.count(neg_expr)!=0)
{
it->cond_expr=true_exprt();
it->ssa_rhs=true_exprt();
it->guard=false_exprt();
SSA_step.cond_expr = true_exprt();
SSA_step.ssa_rhs = true_exprt();
SSA_step.guard = false_exprt();
sliced_SSA_steps++;
if(it->is_output() || it->is_location())
if(SSA_step.is_output() || SSA_step.is_location())
trace_loc_sliced++;
sliced_SSA_step=true;
break; // Sliced, so no need to consider the rest
Expand All @@ -443,32 +426,32 @@ void symex_slice_by_tracet::slice_SSA_steps(
}
}

if(!sliced_SSA_step && it->is_assignment())
if(!sliced_SSA_step && SSA_step.is_assignment())
{
if(it->ssa_rhs.id()==ID_if)
if(SSA_step.ssa_rhs.id() == ID_if)
{
conds_seen++;
exprt cond_copy(to_if_expr(it->ssa_rhs).cond());
exprt cond_copy(to_if_expr(SSA_step.ssa_rhs).cond());
simplify(cond_copy, ns);

if(implications.count(cond_copy)!=0)
{
sliced_conds++;
exprt t_copy1(to_if_expr(it->ssa_rhs).true_case());
exprt t_copy2(to_if_expr(it->ssa_rhs).true_case());
it->ssa_rhs=t_copy1;
it->cond_expr.op1().swap(t_copy2);
exprt t_copy1(to_if_expr(SSA_step.ssa_rhs).true_case());
exprt t_copy2(to_if_expr(SSA_step.ssa_rhs).true_case());
SSA_step.ssa_rhs = t_copy1;
SSA_step.cond_expr.op1().swap(t_copy2);
}
else
{
cond_copy = simplify_expr(boolean_negate(cond_copy), ns);
if(implications.count(cond_copy)!=0)
{
sliced_conds++;
exprt f_copy1(to_if_expr(it->ssa_rhs).false_case());
exprt f_copy2(to_if_expr(it->ssa_rhs).false_case());
it->ssa_rhs=f_copy1;
it->cond_expr.op1().swap(f_copy2);
exprt f_copy1(to_if_expr(SSA_step.ssa_rhs).false_case());
exprt f_copy2(to_if_expr(SSA_step.ssa_rhs).false_case());
SSA_step.ssa_rhs = f_copy1;
SSA_step.cond_expr.op1().swap(f_copy2);
}
}
}
Expand Down Expand Up @@ -565,15 +548,13 @@ std::set<exprt> symex_slice_by_tracet::implied_guards(exprt e)
}
else if(e.id()==ID_and)
{ // Descend into and
Forall_operands(it, e)
for(const auto &conjunct : e.operands())
{
std::set<exprt> r=implied_guards(*it);
for(std::set<exprt>::iterator i=r.begin();
i!=r.end(); i++)
{
s.insert(*i);
}
const auto imps = implied_guards(conjunct);
for(const auto &guard : imps)
s.insert(guard);
}

return s;
}
else if(e.id()==ID_or)
Expand Down Expand Up @@ -611,11 +592,9 @@ bool symex_slice_by_tracet::implies_false(const exprt e)
{
std::set<exprt> imps=implied_guards(e);

for(std::set<exprt>::iterator
i=imps.begin();
i!=imps.end(); i++)
for(const auto &implied_guard : imps)
{
exprt i_copy = boolean_negate(*i);
exprt i_copy = boolean_negate(implied_guard);
simplify(i_copy, ns);
if(imps.count(i_copy)!=0)
return true;
Expand Down