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Merged
merged 1 commit into from
Oct 16, 2017
Merged

Simplify a broader range of java primitive types #1473

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25 changes: 16 additions & 9 deletions src/util/simplify_expr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -236,22 +236,29 @@ bool simplify_exprt::simplify_typecast(exprt &expr)
return false;
}

// eliminate casts to _Bool
if(expr_type.id()==ID_c_bool &&
op_type.id()!=ID_bool)
{
// casts from boolean to a signed int and back:
// (boolean)(int)boolean -> boolean
if(expr.op0().id()==ID_typecast && op_type.id()==ID_signedbv)
// circular casts through types shorter than `int`
if(op_type==signedbv_typet(32) &&
expr.op0().id()==ID_typecast)
{
if(expr_type==c_bool_typet(8) ||
expr_type==signedbv_typet(8) ||
expr_type==signedbv_typet(16) ||
expr_type==unsignedbv_typet(16))
{
const auto &typecast=to_typecast_expr(expr.op0());
if(typecast.op().type().id()==ID_c_bool)
// We checked that the id was ID_typecast in the enclosing `if`
const auto &typecast=expr_checked_cast<typecast_exprt>(expr.op0());
if(typecast.op().type()==expr_type)
{
expr=typecast.op0();
return false;
}
}
}

// eliminate casts to _Bool
if(expr_type.id()==ID_c_bool &&
op_type.id()!=ID_bool)
{
// rewrite (_Bool)x to (_Bool)(x!=0)
binary_relation_exprt inequality;
inequality.id(op_type.id()==ID_floatbv?ID_ieee_float_notequal:ID_notequal);
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93 changes: 79 additions & 14 deletions unit/util/simplify_expr.cpp
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Expand Up @@ -61,22 +61,87 @@ TEST_CASE("Simplify const pointer offset")
REQUIRE(offset_value==1234);
}

TEST_CASE("Simplify Java boolean -> int -> boolean casts")
namespace
{

void test_unnecessary_cast(const typet &type)
{
config.set_arch("none");

const exprt simplified=simplify_expr(
typecast_exprt(
WHEN("The casts can be removed, they are")
{
const exprt simplified=simplify_expr(
typecast_exprt(
symbol_exprt(
"foo",
java_boolean_type()),
java_int_type()),
java_boolean_type()),
namespacet(symbol_tablet()));

REQUIRE(simplified.id()==ID_symbol);
REQUIRE(simplified.type()==java_boolean_type());
const auto &symbol=to_symbol_expr(simplified);
REQUIRE(symbol.get_identifier()=="foo");
typecast_exprt(symbol_exprt("foo", type), java_int_type()),
type),
namespacet(symbol_tablet()));

REQUIRE(simplified.id()==ID_symbol);
REQUIRE(simplified.type()==type);
const auto &symbol=to_symbol_expr(simplified);
REQUIRE(symbol.get_identifier()=="foo");
}

WHEN("Casts should remain, they are left untouched")
{
{
const exprt simplified=simplify_expr(
typecast_exprt(symbol_exprt("foo", type), java_int_type()),
namespacet(symbol_tablet()));

REQUIRE(simplified.id()==ID_typecast);
REQUIRE(simplified.type()==java_int_type());
}

{
const exprt simplified=simplify_expr(
typecast_exprt(symbol_exprt("foo", java_int_type()), type),
namespacet(symbol_tablet()));

REQUIRE(simplified.id()==ID_typecast);
REQUIRE(simplified.type()==type);
}
}
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You might consider a test that involves much more nesting (int)(short)(int)(short) for example

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Done.


WHEN("Deeply nested casts are present, they are collapsed appropriately")
{
{
const exprt simplified=simplify_expr(
typecast_exprt(
typecast_exprt(
typecast_exprt(
typecast_exprt(
typecast_exprt(symbol_exprt("foo", type), java_int_type()),
type),
java_int_type()),
type),
java_int_type()),
namespacet(symbol_tablet()));

REQUIRE(
simplified==typecast_exprt(symbol_exprt("foo", type), java_int_type()));
}
}
}

} // namespace

TEST_CASE("Simplify Java boolean -> int -> boolean casts")
{
test_unnecessary_cast(java_boolean_type());
}

TEST_CASE("Simplify Java byte -> int -> byte casts")
{
test_unnecessary_cast(java_byte_type());
}

TEST_CASE("Simplify Java char -> int -> char casts")
{
test_unnecessary_cast(java_char_type());
}

TEST_CASE("Simplify Java short -> int -> short casts")
{
test_unnecessary_cast(java_short_type());
}