1

/*

     2

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

     3

 *

     4

 *  Copyright (C) 2009-2012  Mario de Sousa (msousa@fe.up.pt)

     5

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

     6

 *

     7

 *

     8

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

     9

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

    10

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

    11

 *  (at your option) any later version.

    12

 *

    13

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

    14

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

    15

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    16

 *  GNU General Public License for more details.

    17

 *

    18

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

    19

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

    20

 *

    21

 *

    22

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

    23

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

    24

 */

    25

    26

/*

    27

 * An IEC 61131-3 compiler.

    28

 *

    29

 * Based on the

    30

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

    31

 *

    32

 */

    33

    34

    35

#include "lvalue_check.hh"

    36

    37

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

    38

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

    39

    40

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

    41

  if (current_display_error_level >= error_level) {                                                                         \

    42

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

    43

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

    44

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

    45

    fprintf(stderr, __VA_ARGS__);                                                                                           \

    46

    fprintf(stderr, "\n");                                                                                                  \

    47

    error_count++;                                                                                                     \

    48

  }                                                                                                                         \

    49

}

    50

    51

    52

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

    53

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

    54

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

    55

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

    56

    fprintf(stderr, __VA_ARGS__);                                                                                           \

    57

    fprintf(stderr, "\n");                                                                                                  \

    58

    warning_found = true;                                                                                                   \

    59

}

    60

    61

    62

lvalue_check_c::lvalue_check_c(symbol_c *ignore) {

    63

	error_count = 0;

    64

}

    65

    66

lvalue_check_c::~lvalue_check_c(void) {

    67

}

    68

    69

int lvalue_check_c::get_error_count() {

    70

	return error_count;

    71

}

    72

    73

    74

#include <strings.h>

    75

/* No writing to iterator variables (used in FOR loops) inside the loop itself */

    76

void lvalue_check_c::check_assignment_to_controlvar(symbol_c *lvalue) {

    77

	for (unsigned int i = 0; i < control_variables.size(); i++) {

    78

		token_c *lvalue_name = get_var_name_c::get_name(lvalue);

    79

		if (compare_identifiers(lvalue_name, control_variables[i]) == 0) {

    80

			STAGE3_ERROR(0, lvalue, lvalue, "Assignment to FOR control variable is not allowed.");

    81

			break;

    82

		}

    83

	}

    84

}

    85

    86

    87

/* fb_instance.var := ...  is not valid if var is output variable */

    88

/* NOTE, if a fb_instance1.fb_instance2.fb_instance3.var is used, we must iteratively check that none of the 

    89

 *       FB records are declared as OUTPUT variables!!  

    90

 *       This is the reason why we have the while() loop in this function!

    91

 */

    92

void lvalue_check_c::check_assignment_to_output(symbol_c *lvalue) {

    93

	decompose_var_instance_name_c decompose_lvalue(lvalue);

    94

	search_base_type_c            search_base_type;

    95

    96

	symbol_c *struct_elem = decompose_lvalue.next_part();

    97

	symbol_c *type_decl   = search_var_instance_decl->get_decl(struct_elem);

    98

	// symbol_c *type_id  = spec_init_sperator_c::get_spec(type_decl); /* this is not required! search_base_type_c can handle spec_init symbols! */

    99

	symbol_c *basetype_id = search_base_type.get_basetype_id(/*type_id*/ type_decl);

   100

	/* If we can not determine the data type of the element, then the code must have a data type semantic error.

   101

	 * This will have been caught by the data type semantic verifier, so we do not bother with this anymore!

   102

	 */

   103

	if (NULL == basetype_id) return;

   104

   105

	/* Determine if the record/structure element is of a FB type. */

   106

	/* NOTE: If the structure element is not a FB type, then we can quit this check.

   107

	 *       Remember that the standard does not allow a STRUCT data type to have elements that are FB instances!

   108

	 *       Similarly, arrays of FB instances is also not allowed.

   109

	 *       So, as soon as we find one record/structure element that is not a FB, no other record/structure element

   110

	 *       will be of FB type, which means we can quit this check!

   111

	 */

   112

	function_block_declaration_c *fb_decl = function_block_type_symtable.find_value(basetype_id);

   113

	if (function_block_type_symtable.end_value() == fb_decl) return;

   114

   115

	while (NULL != (struct_elem = decompose_lvalue.next_part())) {

   116

		search_var_instance_decl_c   fb_search_var_instance_decl(fb_decl);

   117

		if (search_var_instance_decl_c::output_vt == fb_search_var_instance_decl.get_vartype(struct_elem)) {

   118

			STAGE3_ERROR(0, struct_elem, struct_elem, "Assignment to FB output variable is not allowed.");

   119

			return; /* no need to carry on checking once the first error is found! */

   120

		}

   121

   122

		/* prepare for any possible further record/structure elements */

   123

		type_decl   = fb_search_var_instance_decl.get_decl(struct_elem);

   124

		basetype_id = search_base_type.get_basetype_id(type_decl);

   125

		if (NULL == basetype_id) return; /* same comment as above... */

   126

		fb_decl = function_block_type_symtable.find_value(basetype_id);

   127

		if (function_block_type_symtable.end_value() == fb_decl) return; /* same comment as above... */

   128

	}

   129

}

   130

   131

   132

/*  No writing to CONSTANTs */

   133

void lvalue_check_c::check_assignment_to_constant(symbol_c *lvalue) {

   134

	unsigned int option = search_var_instance_decl->get_option(lvalue);

   135

	if (option == search_var_instance_decl_c::constant_opt) {

   136

		STAGE3_ERROR(0, lvalue, lvalue, "Assignment to CONSTANT variables is not be allowed.");

   137

	}

   138

}

   139

   140

   141

/*  No assigning values to expressions. */

   142

void lvalue_check_c::check_assignment_to_expression(symbol_c *lvalue) {

   143

	/* TODO: check whether the lvalue is an expresion! */

   144

	/* This may occur in function invocations, when passing values (possibly an expression) to one 

   145

	 * of the function's OUTPUT or IN_OUT parameters.

   146

	 */

   147

}

   148

   149

   150

   151

void lvalue_check_c::verify_is_lvalue(symbol_c *lvalue) {

   152

	check_assignment_to_expression(lvalue);

   153

	check_assignment_to_controlvar(lvalue);

   154

	check_assignment_to_output(lvalue);

   155

	check_assignment_to_constant(lvalue);

   156

}

   157

   158

   159

   160

   161

/* check whether all values passed to OUT or IN_OUT parameters are legal lvalues. */

   168

void lvalue_check_c::check_nonformal_call(symbol_c *f_call, symbol_c *f_decl) {

   201

   202

   203

/* check whether all values passed to OUT or IN_OUT parameters are legal lvalues. */

   204

void lvalue_check_c::check_formal_call(symbol_c *f_call, symbol_c *f_decl) {

   205

	/* if data type semantic verification was unable to determine which function is being called,

   206

	 * then it does not make sense to go ahead and check for lvalues to unknown parameters.

   207

	 * We simply bug out!

   208

	 */

   209

	if (NULL == f_decl) return;

   210

   211

	symbol_c *call_param_name;

   212

	function_param_iterator_c       fp_iterator(f_decl);

   213

	function_call_param_iterator_c fcp_iterator(f_call);

   214

   215

	/* Iterating through the formal parameters of the function call */

   216

	while((call_param_name = fcp_iterator.next_f()) != NULL) {

   217

   218

		/* Obtaining the value being passed in the function call */

   219

		symbol_c *call_param_value = fcp_iterator.get_current_value();

   220

		if (NULL == call_param_value) ERROR;

   221

   222

		/* Find the corresponding parameter in function declaration, and it's direction (IN, OUT, IN_OUT) */

   223

		identifier_c *param_name = fp_iterator.search(call_param_name);

   224

		function_param_iterator_c::param_direction_t param_direction = fp_iterator.param_direction();

   225

   226

		/* We only check if 'call_param_value' is a valid lvalue if the value is being passed

   227

		 * to a valid paramater of the function being called, and that parameter is either OUT or IN_OUT.

   228

		 */

   229

		if ((param_name != NULL) && ((function_param_iterator_c::direction_out == param_direction) || (function_param_iterator_c::direction_inout == param_direction))) {

   230

			verify_is_lvalue(call_param_value);

   231

		}

   232

	}

   233

}

   234

   235

   236

   237

   238

   239

   240

   241

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

   242

/* B 1.5 - Program organisation units */

   243

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

   244

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

   245

/* B 1.5.1 - Functions */

   246

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

   247

void *lvalue_check_c::visit(function_declaration_c *symbol) {

   248

	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   249

	search_var_instance_decl = new search_var_instance_decl_c(symbol);

   250

	symbol->function_body->accept(*this);

   251

	delete search_varfb_instance_type;

   252

	delete search_var_instance_decl;

   253

	search_varfb_instance_type = NULL;

   254

	search_var_instance_decl = NULL;

   255

	return NULL;

   256

}

   257

   258

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

   259

/* B 1.5.2 - Function blocks */

   260

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

   261

void *lvalue_check_c::visit(function_block_declaration_c *symbol) {

   262

	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   263

	search_var_instance_decl = new search_var_instance_decl_c(symbol);

   264

	symbol->fblock_body->accept(*this);

   265

	delete search_varfb_instance_type;

   266

	delete search_var_instance_decl;

   267

	search_varfb_instance_type = NULL;

   268

	search_var_instance_decl = NULL;

   269

	return NULL;

   270

}

   271

   272

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

   273

/* B 1.5.3 - Programs */

   274

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

   275

void *lvalue_check_c::visit(program_declaration_c *symbol) {

   276

	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   277

	search_var_instance_decl = new search_var_instance_decl_c(symbol);

   278

	symbol->function_block_body->accept(*this);

   279

	delete search_varfb_instance_type;

   280

	delete search_var_instance_decl;

   281

	search_varfb_instance_type = NULL;

   282

	search_var_instance_decl = NULL;

   283

	return NULL;

   284

}

   285

   286

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

   287

/* B.3 - Language ST (Structured Text) */

   288

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

   289

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

   290

/* B 3.1 - Expressions */

   291

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

   292

// SYM_REF3(function_invocation_c, function_name, formal_param_list, nonformal_param_list, symbol_c *called_function_declaration; int extensible_param_count; std::vector <symbol_c *> candidate_functions;)

   293

void *lvalue_check_c::visit(function_invocation_c *symbol) {

   294

	if (NULL != symbol->formal_param_list   )  check_formal_call   (symbol, symbol->called_function_declaration);

   295

	if (NULL != symbol->nonformal_param_list)  check_nonformal_call(symbol, symbol->called_function_declaration);

   296

	return NULL;

   297

}

   298

   299

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

   300

/* B 3.2.1 Assignment Statements */

   301

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

   302

void *lvalue_check_c::visit(assignment_statement_c *symbol) {

   303

	verify_is_lvalue(symbol->l_exp);

   304

	/* We call visit r_exp to check function_call */

   305

	symbol->r_exp->accept(*this);

   306

	return NULL;

   307

}

   308

   309

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

   310

/* B 3.2.4 Iteration Statements */

   311

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

   312

void *lvalue_check_c::visit(for_statement_c *symbol) {

   313

	control_variables.push_back(get_var_name_c::get_name(symbol->control_variable));

   314

	symbol->statement_list->accept(*this);

   315

	control_variables.pop_back();

   316

	return NULL;

   317

}

   318

   319

   320

   321

   322

   323

   324