1

/*

     2

 *  matiec - a compiler for the programming languages defined in IEC 61131-3

     3

 *

     4

 *  Copyright (C) 2003-2011  Mario de Sousa (msousa@fe.up.pt)

     5

 *  Copyright (C) 2012       Manuele Conti (conti.ma@alice.it)

     6

 *

     7

 *  This program is free software: you can redistribute it and/or modify

     8

 *  it under the terms of the GNU General Public License as published by

     9

 *  the Free Software Foundation, either version 3 of the License, or

    10

 *  (at your option) any later version.

    11

 *

    12

 *  This program is distributed in the hope that it will be useful,

    13

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

    14

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    15

 *  GNU General Public License for more details.

    16

 *

    17

 *  You should have received a copy of the GNU General Public License

    18

 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

    19

 *

    20

 *

    21

 * This code is made available on the understanding that it will not be

    22

 * used in safety-critical situations without a full and competent review.

    23

 */

    24

    25

/*

    26

 * An IEC 61131-3 compiler.

    27

 *

    28

 * Based on the

    29

 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)

    30

 *

    31

 */

    32

    33

    34

    35

/* TODO: 

    36

 *         - Add support for comparison (= and !=) of enumeration literals!

    37

 *              We will need to add another const_value entry to the symbol_c, containing the 

    38

 *              possible enumeration value of the enum constant!

    39

 *              Doing this will allow us to more easily implement a constant_propagation_c later on!

    40

 *

    41

 *         - Add support for comparison (= and !=) of the exact same variable

    42

 *                (e.g. if (int_v = int_v) then ...)

    43

 */

    44

    45

    46

    47

/* Do constant folding...

    48

 *

    49

 * I.e., Determine the value of all expressions in which only constant values (i.e. literals) are used.

    50

 * The (constant) result of each operation is stored (annotated) in the respective operation symbol 

    51

 * (e.g.: add_expression_c) in the abstract syntax tree,

    52

 *

    53

 * For example:

    54

 *       2 + 3         -> the constant value '5'    is stored in the add_expression_c symbol.

    55

 *       22.2 - 5.0    -> the constant value '17.2' is stored in the add_expression_c symbol.

    56

 *       etc...

    57

 *

    58

 *

    59

 * NOTE 1 

    60

 *      Some operations and constants can have multiple data types. For example,

    61

 *        1 AND 0

    62

 *      may be either a BOOL, BYTE, WORD or LWORD.

    63

 *

    64

 *      The same happens with 

    65

 *        1 + 2

    66

 *      which may be signed (e.g. INT) or unsigned (UINT)

    67

 *

    68

 *      For the above reason, instead of storing a single constant value, we actually store 4:

    69

 *        - bool

    70

 *        - uint64

    71

 *        -  int64

    72

 *        - real64

    73

 *

    74

 *      Additionally, since the result of an operation may result in an overflow, we actually

    75

 *      store the result inside a struct (defined in absyntax.hh)

    76

 *

    77

 *             ** During stage 3 (semantic analysis/checking) we will be doing constant folding.

    78

 *              * That algorithm will anotate the abstract syntax tree with the result of operations

    79

 *              * on literals (i.e. 44 + 55 will store the result 99).

    80

 *              * Since the same source code (e.g. 1 + 0) may actually be a BOOL or an ANY_INT,

    81

 *              * or an ANY_BIT, we need to handle all possibilities, and determine the result of the

    82

 *              * operation assuming each type.

    83

 *              * For this reason, we have one entry for each possible type, with some expressions

    84

 *              * having more than one entry filled in!

    85

 *              **

    86

 *             typedef enum { cs_undefined,   // not defined --> const_value is not valid!

    87

 *                            cs_const_value, // const value is valid

    88

 *                            cs_overflow     // result produced overflow or underflow --> const_value is not valid!

    89

 *                          } const_status_t;

    90

 *    

    91

 *             typedef struct {

    92

 *                 const_status_t status;

    93

 *                 real64_t       value; 

    94

 *             } const_value_real64_t;

    95

 *             const_value_real64_t *const_value_real64; // when NULL --> UNDEFINED

    96

 *             

    97

 *             typedef struct {

    98

 *                 const_status_t status;

    99

 *                 int64_t        value; 

   100

 *             } const_value_int64_t;

   101

 *             const_value_int64_t *const_value_int64; // when NULL --> UNDEFINED

   102

 *             

   103

 *             typedef struct {

   104

 *                 const_status_t status;

   105

 *                 uint64_t       value; 

   106

 *             } const_value_uint64_t;

   107

 *             const_value_uint64_t *const_value_uint64; // when NULL --> UNDEFINED

   108

 *             

   109

 *             typedef struct {

   110

 *                 const_status_t status;

   111

 *                 bool           value; 

   112

 *             } const_value_bool_t;

   113

 *             const_value_bool_t *const_value_bool; // when NULL --> UNDEFINED

   114

 *

   115

 *

   116

 *

   117

 * NOTE 2 

   118

 *    This file does not print out any error messages!

   119

 *    We cannot really print out error messages when we find an overflow. Since each operation

   120

 *    (symbol in the absract syntax tree for that operation) will have up to 4 constant results,

   121

 *    it may happen that some of them overflow, while other do not.

   122

 *    We must wait for data type checking to determine the exact data type of each expression

   123

 *    before we can decide whether or not we should print out an overflow error message.

   124

 *

   125

 *    For this reason, this visitor merely annotates the abstract syntax tree, and leaves the

   126

 *    actuall printing of errors for the print_datatype_errors_c class!

   127

 */

   128

   129

#include "constant_folding.hh"

   130

#include <stdlib.h> /* required for malloc() */

   131

   132

#include <string.h>  /* required for strlen() */

   133

// #include <stdlib.h>  /* required for atoi() */

   134

#include <errno.h>   /* required for errno */

   135

   136

#include "../main.hh" // required for uint8_t, real_64_t, ..., and the macros NAN, INFINITY, INT8_MAX, REAL32_MAX, ... */

   137

   138

   139

   140

   141

   142

   143

#define FIRST_(symbol1, symbol2) (((symbol1)->first_order < (symbol2)->first_order)   ? (symbol1) : (symbol2))

   144

#define  LAST_(symbol1, symbol2) (((symbol1)->last_order  > (symbol2)->last_order)    ? (symbol1) : (symbol2))

   145

   146

#define STAGE3_ERROR(error_level, symbol1, symbol2, ...) {                                                                  \

   147

  if (current_display_error_level >= error_level) {                                                                         \

   148

    fprintf(stderr, "%s:%d-%d..%d-%d: error: ",                                                                             \

   149

            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\

   150

                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\

   151

    fprintf(stderr, __VA_ARGS__);                                                                                           \

   152

    fprintf(stderr, "\n");                                                                                                  \

   153

    error_count++;                                                                                                     \

   154

  }                                                                                                                         \

   155

}

   156

   157

   158

#define STAGE3_WARNING(symbol1, symbol2, ...) {                                                                             \

   159

    fprintf(stderr, "%s:%d-%d..%d-%d: warning: ",                                                                           \

   160

            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\

   161

                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\

   162

    fprintf(stderr, __VA_ARGS__);                                                                                           \

   163

    fprintf(stderr, "\n");                                                                                                  \

   164

    warning_found = true;                                                                                                   \

   165

}

   166

   167

   168

   169

   170

   171

   172

   173

   174

   175

   176

   177

   178

#define SET_CVALUE(dtype, symbol, new_value) {((symbol)->const_value._##dtype.value) = new_value; ((symbol)->const_value._##dtype.status) = symbol_c::cs_const_value;}

   179

#define GET_CVALUE(dtype, symbol)             ((symbol)->const_value._##dtype.value)

   180

#define SET_OVFLOW(dtype, symbol)             ((symbol)->const_value._##dtype.status) = symbol_c::cs_overflow

   181

#define SET_NONCONST(dtype, symbol)           ((symbol)->const_value._##dtype.status) = symbol_c::cs_non_const

   182

   183

#define VALID_CVALUE(dtype, symbol)           (symbol_c::cs_const_value == (symbol)->const_value._##dtype.status)

   184

#define IS_OVFLOW(dtype, symbol)              (symbol_c::cs_overflow    == (symbol)->const_value._##dtype.status)

   185

#define ISZERO_CVALUE(dtype, symbol)          ((VALID_CVALUE(dtype, symbol)) && (GET_CVALUE(dtype, symbol) == 0))

   186

   187

#define ISEQUAL_CVALUE(dtype, symbol1, symbol2) \

   188

	(VALID_CVALUE(dtype, symbol1) && VALID_CVALUE(dtype, symbol2) && (GET_CVALUE(dtype, symbol1) == GET_CVALUE(dtype, symbol2))) 

   189

   190

#define DO_BINARY_OPER(oper_type, operation, res_type, operand1, operand2) {                                             \

   191

	if (VALID_CVALUE(oper_type, operand1) && VALID_CVALUE(oper_type, operand2))                                       \

   192

		SET_CVALUE(res_type, symbol, GET_CVALUE(oper_type, operand1) operation GET_CVALUE(oper_type, operand2));  \

   193

}

   194

   195

#define DO_UNARY_OPER(dtype, operation, operand) {                                                                        \

   196

	if (VALID_CVALUE(dtype, operand))                                                                                 \

   197

		SET_CVALUE(dtype, symbol, operation GET_CVALUE(dtype, operand));                                          \

   198

}

   199

   200

   201

   202

   203

   204

/***********************************************************************/

   205

/***********************************************************************/

   206

/***********************************************************************/

   207

/***            convert string to numerical value                    ***/

   208

/***********************************************************************/

   209

/***********************************************************************/

   210

/***********************************************************************/

   211

   212

   213

   214

  /* To allow the compiler to be portable, we cannot assume that int64_t is mapped onto long long int,

   215

   * so we cannot call strtoll() and strtoull() in extract_int64() and extract_uint64().

   216

   *

   217

   * So, we create our own strtouint64() and strtoint64() functions.

   218

   * (We actually call them matiec_strtoint64() so they will not clash with any function

   219

   *  that may be added to the standard library in the future).

   220

   * We actually create several of each, and let the compiler choose which is the correct one,

   221

   * by having it resolve the call to the overloaded function. For the C++ compiler to be able

   222

   * to resolve this ambiguity, we need to add a dummy parameter to each function!

   223

   *

   224

   * TODO: support platforms (where the compiler will run) in which int64_t is mapped onto int !!

   225

   *       Is this really needed?

   226

   *       Currently, when trying to compile matiec on sych a platform, the C++ compiler will not

   227

   *       find any apropriate matiec_strtoint64() to call, so matiec will not be able to be compiled.

   228

   *       If you need this, you are welcome to fix it yourself...

   229

   */

   230

static  int64_t matiec_strtoint64 (         long      int *dummy, const char *nptr, char **endptr, int base) {return strtol  (nptr, endptr, base);}

   231

static  int64_t matiec_strtoint64 (         long long int *dummy, const char *nptr, char **endptr, int base) {return strtoll (nptr, endptr, base);}

   232

   233

static uint64_t matiec_strtouint64(unsigned long      int *dummy, const char *nptr, char **endptr, int base) {return strtoul (nptr, endptr, base);}

   234

static uint64_t matiec_strtouint64(unsigned long long int *dummy, const char *nptr, char **endptr, int base) {return strtoull(nptr, endptr, base);}

   235

   236

   237

/* extract the value of an integer from an integer_c object !! */

   238

/* NOTE: it must ignore underscores! */

   239

/* NOTE: To follow the basic structure used throughout the compiler's code, we should really be

   240

 * writing this as a visitor_c (and do away with the dynamic casts!), but since we only have 3 distinct 

   241

 * symbol class types to handle, it is probably easier to read if we write it as a standard function... 

   242

 */

   243

int64_t extract_int64_value(symbol_c *sym, bool *overflow) {

   244

  int64_t      ret;

   245

  std::string  str = "";

   246

  char        *endptr;

   247

  const char  *value;

   248

  int          base;

   249

  integer_c         *integer;

   250

  hex_integer_c     *hex_integer;

   251

  octal_integer_c   *octal_integer;

   252

  binary_integer_c  *binary_integer;

   253

   254

   if       ((integer        = dynamic_cast<integer_c *>(sym))        != NULL) {value = integer       ->value + 0; base = 10;}

   255

   else  if ((hex_integer    = dynamic_cast<hex_integer_c *>(sym))    != NULL) {value = hex_integer   ->value + 3; base = 16;}

   256

   else  if ((octal_integer  = dynamic_cast<octal_integer_c *>(sym))  != NULL) {value = octal_integer ->value + 2; base =  8;}

   257

   else  if ((binary_integer = dynamic_cast<binary_integer_c *>(sym)) != NULL) {value = binary_integer->value + 2; base =  2;}

   258

   else  ERROR;

   259

   260

  for(unsigned int i = 0; i < strlen(value); i++)

   261

    if (value[i] != '_')  str += value[i];

   262

   263

  errno = 0; // since strtoXX() may legally return 0, we must set errno to 0 to detect errors correctly!

   264

  ret = matiec_strtoint64((int64_t *)NULL, str.c_str(), &endptr, base);

   265

  if (overflow != NULL)

   266

    *overflow = (errno == ERANGE);

   267

  if (((errno != 0) && (errno != ERANGE)) || (*endptr != '\0'))

   268

    ERROR;

   269

   270

  return ret;

   271

}

   272

   273

   274

   275

uint64_t extract_uint64_value(symbol_c *sym, bool *overflow) {

   276

  uint64_t     ret;

   277

  std::string  str = "";

   278

  char        *endptr;

   279

  const char  *value;

   280

  int          base;

   281

  integer_c         *integer;

   282

  hex_integer_c     *hex_integer;

   283

  octal_integer_c   *octal_integer;

   284

  binary_integer_c  *binary_integer;

   285

   286

   if       ((integer        = dynamic_cast<integer_c *>(sym))        != NULL) {value = integer       ->value + 0; base = 10;}

   287

   else  if ((hex_integer    = dynamic_cast<hex_integer_c *>(sym))    != NULL) {value = hex_integer   ->value + 3; base = 16;}

   288

   else  if ((octal_integer  = dynamic_cast<octal_integer_c *>(sym))  != NULL) {value = octal_integer ->value + 2; base =  8;}

   289

   else  if ((binary_integer = dynamic_cast<binary_integer_c *>(sym)) != NULL) {value = binary_integer->value + 2; base =  2;}

   290

   else  ERROR;

   291

   292

  for(unsigned int i = 0; i < strlen(value); i++)

   293

    if (value[i] != '_')  str += value[i];

   294

   295

  errno = 0; // since strtoXX() may legally return 0, we must set errno to 0 to detect errors correctly!

   296

  ret = matiec_strtouint64((uint64_t *)NULL, str.c_str(), &endptr, base);

   297

  if (overflow != NULL)

   298

    *overflow = (errno == ERANGE);

   299

  if (((errno != 0) && (errno != ERANGE)) || (*endptr != '\0'))

   300

    ERROR;

   301

   302

  return ret;

   303

}

   304

   305

   306

   307

/* extract the value of a real from an real_c object !! */

   308

/* NOTE: it must ignore underscores! */

   309

/* From iec_bison.yy

   310

 *  real:

   311

 *   real_token		{$$ = new real_c($1, locloc(@$));}

   312

 * | fixed_point_token	{$$ = new real_c($1, locloc(@$));}

   313

 *

   314

 * From iec_flex.ll

   315

 * {real}			{yylval.ID=strdup(yytext); return real_token;}

   316

 * {fixed_point}		{yylval.ID=strdup(yytext); return fixed_point_token;}

   317

 *

   318

 * real		{integer}\.{integer}{exponent}

   319

 * fixed_point		{integer}\.{integer}

   320

 * exponent        [Ee]([+-]?){integer}

   321

 * integer         {digit}((_?{digit})*)

   322

 */

   323

real64_t extract_real_value(symbol_c *sym, bool *overflow) {

   324

  std::string str = "";

   325

  real_c *real_sym;

   326

  char   *endptr;

   327

  real64_t ret;

   328

   329

  if ((real_sym = dynamic_cast<real_c *>(sym)) == NULL) ERROR;

   330

  for(unsigned int i = 0; i < strlen(real_sym->value); i++)

   331

    if (real_sym->value[i] != '_') str += real_sym->value[i];

   332

   333

  errno = 0; // since strtoXX() may legally return 0, we must set errno to 0 to detect errors correctly!

   334

  #if    (real64_t  == float)

   335

    ret = strtof(str.c_str(),  &endptr);

   336

  #elif  (real64_t  == double)

   337

    ret = strtod(str.c_str(),  &endptr);

   338

  #elif  (real64_t  == long_double)

   339

    ret = strtold(str.c_str(), &endptr);

   340

  #else 

   341

    #error Could not determine which data type is being used for real64_t (defined in absyntax.hh). Aborting!

   342

  #endif

   343

  if (overflow != NULL)

   344

    *overflow = (errno == ERANGE);

   345

  if (((errno != 0) && (errno != ERANGE)) || (*endptr != '\0'))

   346

    ERROR;

   347

   348

  return ret;

   349

}

   350

   351

   352

   353

   354

   355

/***********************************************************************/

   356

/***********************************************************************/

   357

/***********************************************************************/

   358

/***        Functions to check for overflow situation                ***/

   359

/***********************************************************************/

   360

/***********************************************************************/

   361

/***********************************************************************/

   362

   363

   364

/* NOTE:

   365

 *   Most of the conditions to detect overflows on signed and unsigned integer operations were adapted from

   366

 *   https://www.securecoding.cert.org/confluence/display/seccode/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow?showComments=false

   367

 *   https://www.securecoding.cert.org/confluence/display/seccode/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap

   368

 */

   369

   370

/* NOTE: If at all possible, all overflow tests are done by pre-condition tests, i.e. tests that 

   371

 *       can be run _before_ the operation is executed, and therefore without accessing the result!

   372

 *

   373

 *       The exception is for real/floating point values, that simply test if the result is NaN (not a number).

   374

 */

   375

   376

/* res = a + b */

   377

static void CHECK_OVERFLOW_uint64_SUM(symbol_c *res, symbol_c *a, symbol_c *b) {

   378

	if (!VALID_CVALUE(uint64, res))

   379

		return;

   380

	/* Test by post-condition: If sum is smaller than either operand => overflow! */

   381

	// if (GET_CVALUE(uint64, res) < GET_CVALUE(uint64, a))

   382

	/* Test by pre-condition: If (UINT64_MAX - a) < b => overflow! */

   383

	if ((UINT64_MAX - GET_CVALUE(uint64, a)) < GET_CVALUE(uint64, b))

   384

		SET_OVFLOW(uint64, res);

   385

}

   386

   387

   388

/* res = a - b */

   389

static void CHECK_OVERFLOW_uint64_SUB(symbol_c *res, symbol_c *a, symbol_c *b) {

   390

	if (!VALID_CVALUE(uint64, res))

   391

		return;

   392

	/* Test by post-condition: If diference is larger than a => overflow! */

   393

	// if (GET_CVALUE(uint64, res) > GET_CVALUE(uint64, a))

   394

	/* Test by pre-condition: if b > a => overflow! */

   395

	if (GET_CVALUE(uint64, b) > GET_CVALUE(uint64, a))

   396

		SET_OVFLOW(uint64, res);

   397

}

   398

   399

   400

/* res = a * b */

   401

static void CHECK_OVERFLOW_uint64_MUL(symbol_c *res, symbol_c *a, symbol_c *b) {

   402

	if (!VALID_CVALUE(uint64, res))

   403

		return;

   404

	/* Test by pre-condition: If (UINT64_MAX / a) < b => overflow! */

   405

	if ((UINT64_MAX / GET_CVALUE(uint64, a)) < GET_CVALUE(uint64, b))

   406

		SET_OVFLOW(uint64, res);

   407

}

   408

   409

   410

/* res = a / b */

   411

static void CHECK_OVERFLOW_uint64_DIV(symbol_c *res, symbol_c *a, symbol_c *b) {

   412

	if (!VALID_CVALUE(uint64, res))

   413

		return;

   414

	if (GET_CVALUE(uint64, b) == 0) /* division by zero! */

   415

		SET_OVFLOW(uint64, res);

   416

}

   417

   418

   419

/* res = a MOD b */

   420

static void CHECK_OVERFLOW_uint64_MOD(symbol_c *res, symbol_c *a, symbol_c *b) {

   421

	if (!VALID_CVALUE(uint64, res))

   422

		return;

   423

	/* no overflow condition exists, including division by zero, which IEC 61131-3 considers legal for MOD operation! */

   424

	if (false) 

   425

		SET_OVFLOW(uint64, res);

   426

}

   427

   428

   429

/* res = - a */

   430

static void CHECK_OVERFLOW_uint64_NEG(symbol_c *res, symbol_c *a) {

   431

	/* The only legal operation is res = -0, everything else is an overflow! */

   432

	if (VALID_CVALUE(uint64, a) && (GET_CVALUE(uint64, a) != 0))

   433

		SET_OVFLOW(uint64, res);

   434

}

   435

   436

   437

   438

   439

   440

   441

/* res = a + b */

   442

static void CHECK_OVERFLOW_int64_SUM(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   443

	if (!VALID_CVALUE(int64, res))

   444

		return;

   445

	int64_t a = GET_CVALUE(int64, a_ptr);

   446

	int64_t b = GET_CVALUE(int64, b_ptr);

   447

	/* The following test is valid no matter what representation is being used (e.g. two's complement, etc...) */

   448

	if (((b > 0) && (a > (INT64_MAX - b)))

   449

	 || ((b < 0) && (a < (INT64_MIN - b))))

   450

		SET_OVFLOW(int64, res);

   451

}

   452

   453

   454

/* res = a - b */

   455

static void CHECK_OVERFLOW_int64_SUB(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   456

	if (!VALID_CVALUE(int64, res))

   457

		return;

   458

	int64_t a = GET_CVALUE(int64, a_ptr);

   459

	int64_t b = GET_CVALUE(int64, b_ptr);

   460

	/* The following test is valid no matter what representation is being used (e.g. two's complement, etc...) */

   461

	if (((b > 0) && (a < (INT64_MIN + b)))

   462

	 || ((b < 0) && (a > (INT64_MAX + b))))

   463

		SET_OVFLOW(int64, res);

   464

}

   465

   466

   467

/* res = a * b */

   468

static void CHECK_OVERFLOW_int64_MUL(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   469

	if (!VALID_CVALUE(int64, res))

   470

		return;

   471

	int64_t a = GET_CVALUE(int64, a_ptr);

   472

	int64_t b = GET_CVALUE(int64, b_ptr);

   473

	if (   ( (a > 0) &&  (b > 0) &&             (a > (INT64_MAX / b))) 

   474

	    || ( (a > 0) && !(b > 0) &&             (b < (INT64_MIN / a))) 

   475

	    || (!(a > 0) &&  (b > 0) &&             (a < (INT64_MIN / b))) 

   476

	    || (!(a > 0) && !(b > 0) && (a != 0) && (b < (INT64_MAX / a))))

   477

		SET_OVFLOW(int64, res);

   478

}

   479

   480

   481

/* res = a / b */

   482

static void CHECK_OVERFLOW_int64_DIV(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   483

	if (!VALID_CVALUE(int64, res))

   484

		return;

   485

	int64_t a = GET_CVALUE(int64, a_ptr);

   486

	int64_t b = GET_CVALUE(int64, b_ptr);

   487

	if ((b == 0) || ((a == INT64_MIN) && (b == -1)))

   488

		SET_OVFLOW(int64, res);

   489

}

   490

   491

   492

/* res = a MOD b */

   493

static void CHECK_OVERFLOW_int64_MOD(symbol_c *res, symbol_c *a_ptr, symbol_c *b_ptr) {

   494

	if (!VALID_CVALUE(int64, res))

   495

		return;