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Remove tautological typecasts #1438

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Merged
merged 3 commits into from
Oct 4, 2017
Merged

Remove tautological typecasts #1438

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0e2b13f
Remove tautological typecasts
reuk Oct 2, 2017
9ea7414
Set up config in unit tests
reuk Oct 3, 2017
1d87928
Add unit test for new behavior
reuk Oct 3, 2017
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12 changes: 12 additions & 0 deletions src/util/simplify_expr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -240,6 +240,18 @@ bool simplify_exprt::simplify_typecast(exprt &expr)
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)
{
const auto &typecast=to_typecast_expr(expr.op0());
if(typecast.op().type().id()==ID_c_bool)
{
expr=typecast.op0();
return false;
}
}

// 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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26 changes: 26 additions & 0 deletions unit/util/simplify_expr.cpp
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Expand Up @@ -8,8 +8,10 @@

#include <catch.hpp>

#include <java_bytecode/java_types.h>
#include <util/arith_tools.h>
#include <util/c_types.h>
#include <util/config.h>
#include <util/namespace.h>
#include <util/pointer_predicates.h>
#include <util/simplify_expr.h>
Expand All @@ -18,6 +20,8 @@

TEST_CASE("Simplify pointer_offset(address of array index)")
{
config.set_arch("none");

symbol_tablet symbol_table;
namespacet ns(symbol_table);

Expand All @@ -38,6 +42,8 @@ TEST_CASE("Simplify pointer_offset(address of array index)")

TEST_CASE("Simplify const pointer offset")
{
config.set_arch("none");

symbol_tablet symbol_table;
namespacet ns(symbol_table);

Expand All @@ -54,3 +60,23 @@ TEST_CASE("Simplify const pointer offset")
REQUIRE(!to_integer(simp, offset_value));
REQUIRE(offset_value==1234);
}

TEST_CASE("Simplify Java boolean -> int -> boolean casts")
{
config.set_arch("none");

const exprt simplified=simplify_expr(
typecast_exprt(
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");
}