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SMT2 backend: minus on void pointers #7338

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Merged
merged 1 commit into from
Nov 15, 2022
Merged

SMT2 backend: minus on void pointers #7338

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2 changes: 1 addition & 1 deletion regression/cbmc/void_pointer3/test.desc
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
CORE broken-smt-backend gcc-only
CORE gcc-only
main.c

^EXIT=0$
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24 changes: 18 additions & 6 deletions src/solvers/smt2/smt2_conv.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3825,11 +3825,23 @@ void smt2_convt::convert_minus(const minus_exprt &expr)
expr.op1().type().id()==ID_pointer)
{
// Pointer difference
auto element_size =
pointer_offset_size(to_pointer_type(expr.op0().type()).base_type(), ns);
CHECK_RETURN(element_size.has_value() && *element_size >= 1);
const auto &base_type = to_pointer_type(expr.op0().type()).base_type();
mp_integer element_size;
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🤔 It might be nice if this code which works out the element_size were to be factored out into a separate function. This commit seems to be duplicating the code from pointer addition.


if(*element_size >= 2)
if(base_type.id() == ID_empty)
{
// Pointer arithmetic on void is a gcc extension.
// https://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Pointer-Arith.html
element_size = 1;
}
else
{
auto element_size_opt = pointer_offset_size(base_type, ns);
CHECK_RETURN(element_size_opt.has_value() && *element_size_opt >= 1);
element_size = *element_size_opt;
}

if(element_size >= 2)
out << "(bvsdiv ";

INVARIANT(
Expand All @@ -3843,8 +3855,8 @@ void smt2_convt::convert_minus(const minus_exprt &expr)
convert_expr(expr.op1());
out << ")";

if(*element_size >= 2)
out << " (_ bv" << *element_size << " " << boolbv_width(expr.type())
if(element_size >= 2)
out << " (_ bv" << element_size << " " << boolbv_width(expr.type())
<< "))";
}
else
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