fixed #4726: simplify bitwise Not (~ %num%)

lib/mathlib.cpp

@@ -339,6 +339,11 @@ std::string MathLib::calculate(const std::string &first, const std::string &seco
     }
 }
 
+std::string MathLib::bitwiseNot(const std::string &number)
+{
+    return MathLib::longToString(~MathLib::toLongNumber(number));
+}
+
 std::string MathLib::sin(const std::string &tok)
 {
     return doubleToString(std::sin(toDoubleNumber(tok)));

lib/mathlib.h

@@ -50,6 +50,7 @@ public:
     static std::string multiply(const std::string & first, const std::string & second);
     static std::string divide(const std::string & first, const std::string & second);
     static std::string mod(const std::string & first, const std::string & second);
+    static std::string bitwiseNot(const std::string &number);
     static std::string calculate(const std::string & first, const std::string & second, char action);
 
     static std::string sin(const std::string & tok);

lib/templatesimplifier.cpp

@@ -992,6 +992,12 @@ bool TemplateSimplifier::simplifyCalculations(Token *_tokens)
                  tok->str() == MathLib::multiply(tok->strAt(2), MathLib::divide(tok->str(), tok->strAt(2)))) {
             tok->deleteNext(2);
         }
+        // simplify bitwise not operations, e.g: ~0 --> -1
+        else if (Token::Match(tok, "~ %num%")) {
+            const std::string result = MathLib::bitwiseNot(tok->strAt(1));
+            tok->str(result);
+            tok->deleteNext();
+        }
 
         else {
             ret |= simplifyNumericCalculations(tok);

test/testmathlib.cpp

@@ -41,6 +41,7 @@ private:
         TEST_CASE(isNotEqual)
         TEST_CASE(isLess)
         TEST_CASE(isLessEqual)
+        TEST_CASE(bitwiseNot)
     }
 
     void isGreater() const {
@@ -343,6 +344,11 @@ private:
         ASSERT_EQUALS(true , MathLib::isFloat("1.0E-1"));
         ASSERT_EQUALS(true , MathLib::isFloat("-1.0E+1"));
     }
+
+    void bitwiseNot() const {
+        ASSERT_EQUALS("-1" , MathLib::bitwiseNot("0"));
+        ASSERT_EQUALS("-8" , MathLib::bitwiseNot("7"));
+    }
 };
 
 REGISTER_TEST(TestMathLib)