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Value sets: handle extractbits out of pointers #7339

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Merged
merged 2 commits into from
Nov 19, 2022
Merged

Value sets: handle extractbits out of pointers #7339

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35dc5e7
Value sets: handle extractbits out of pointers
tautschnig Nov 13, 2022
3b8fa07
Value sets: try to extract pointers from any other expression
tautschnig Nov 14, 2022
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38 changes: 35 additions & 3 deletions src/pointer-analysis/value_set.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ Author: Daniel Kroening, [email protected]
#include "value_set.h"

#include <util/arith_tools.h>
#include <util/bitvector_expr.h>
#include <util/byte_operators.h>
#include <util/c_types.h>
#include <util/expr_util.h>
Expand Down Expand Up @@ -589,8 +590,9 @@ void value_sett::get_value_set_rec(
// pointer-to-pointer -- we just ignore these
get_value_set_rec(op, dest, suffix, original_type, ns);
}
else if(op_type.id()==ID_unsignedbv ||
op_type.id()==ID_signedbv)
else if(
op_type.id() == ID_unsignedbv || op_type.id() == ID_signedbv ||
op_type.id() == ID_bv)
{
// integer-to-pointer

Expand Down Expand Up @@ -1052,9 +1054,39 @@ void value_sett::get_value_set_rec(
value_set_with_local_definition.get_value_set_rec(
let_expr.where(), dest, suffix, original_type, ns);
}
else if(auto eb = expr_try_dynamic_cast<extractbits_exprt>(expr))
{
object_mapt pointer_expr_set;
get_value_set_rec(eb->src(), pointer_expr_set, "", eb->src().type(), ns);

for(const auto &object_map_entry : pointer_expr_set.read())
{
offsett offset = object_map_entry.second;

// kill any offset
offset.reset();

insert(dest, object_map_entry.first, offset);
}
}
else
{
insert(dest, exprt(ID_unknown, original_type));
object_mapt pointer_expr_set;
for(const auto &op : expr.operands())
get_value_set_rec(op, pointer_expr_set, "", original_type, ns);

for(const auto &object_map_entry : pointer_expr_set.read())
{
offsett offset = object_map_entry.second;

// kill any offset
offset.reset();

insert(dest, object_map_entry.first, offset);
}

if(pointer_expr_set.read().empty())
insert(dest, exprt(ID_unknown, original_type));
}

#ifdef DEBUG
Expand Down