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/*

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

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 *

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

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 *

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

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

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

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 *  (at your option) any later version.

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 *

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

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

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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 *  GNU General Public License for more details.

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 *

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

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

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 *

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 *

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

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

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 */

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/*

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 * An IEC 61131-3 compiler.

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 *

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 * Based on the

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

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 *

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 */

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/*

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 *  Do flow control analysis of the IEC 61131-3 code.

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 *

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 *  We currently only do this for IL code.

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 *  This class will annotate the abstract syntax tree, by filling in the

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 *  prev_il_instruction variable in the il_instruction_c, so it points to

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 *  the previous il_instruction_c object in the instruction list instruction_list_c.

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 *

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 *  Since IL code can contain jumps (JMP), the same il_instruction may effectively have

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 *  several previous il_instructions. In order to accommodate this, each il_instruction

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 *  will maintain a vector (i..e an array) of pointers to all the previous il_instructions.

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 *  We do however attempt to guarantee that the first element in the vector (array) will preferentially

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 *  point to the il instruction that is right before / imediately preceding the current il instructions, 

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 *  i.e. the first element in the array will tend to point to the previous il_instruction

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 *  that is not a jump JMP IL instruction!

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 *

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 *  The result will essentially be a graph of il_instruction_c objects, each 

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 *  pointing to the previous il_instruction_c object.

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 *

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 *  The reality is we will get several independent and isolated linked lists

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 *  (actually, since we now process labels correctly, this is really a graph):

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 *  one for each block of IL code (e.g. inside a Function, FB or Program).

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 *  Additionally, when the IL code has an expression (expression_c object), we will actually

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 *  have one more isolated linked list for the IL code inside that expression.

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 *

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 *  e.g.

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 *       line_1:   LD 1

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 *       line_2:   ADD (42

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 *       line_3:        ADD B

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 *       line_4:        ADD C 

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 *       line_5:       )

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 *       line_6:   ADD D

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 *       line_7:   ST  E

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 * 

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 *     will result in two independent linked lists:

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 *       main list:  line_7 -> line_6 -> line2 -> line_1

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 *       expr list:  lin4_4 -> line_3 -> (operand of line_2, i.e. '42')

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 * 

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 * 

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 *     In the main list, each:

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 *        line_x: IL_operation IL_operand

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 *      is encoded as

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 *          il_instruction_c(label, il_incomplete_instruction)

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 *      these il_instruction_c objects will point back to the previous il_instruction_c object.

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 *

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 *     In the expr list, each 

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 *        line_x:        IL_operation IL_operand

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 *      is encoded as

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 *          il_simple_instruction_c(il_simple_instruction)

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 *      these il_simple_instruction_c objects will point back to the previous il_simple_instruction_c object,

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 *      except the for the first il_simple_instruction_c object in the list, which will point back to

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 *      the first il_operand (in the above example, '42'), or NULL is it does not exist.

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 *          

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 *

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 * label:

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 *   identifier_c  

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 *   

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 * il_incomplete_instruction:

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 *   il_simple_operation   (il_simple_operation_c, il_function_call_c)

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 * | il_expression         (il_expression_c)

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 * | il_jump_operation     (il_jump_operation_c)

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 * | il_fb_call            (il_fb_call_c)

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 * | il_formal_funct_call  (il_formal_funct_call_c)

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 * | il_return_operator    (RET_operator_c, RETC_operator_c, RETCN_operator_c)

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 *  

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 * 

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 * il_expression_c(il_expr_operator, il_operand, simple_instr_list)

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 * 

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 * il_operand:

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 *   variable            (symbolic_variable_c, direct_variable_c, array_variable_c, structured_variable_c)  

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 * | enumerated_value    (enumerated_value_c)

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 * | constant            (lots of literal classes _c)

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 * 

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 * simple_instr_list:

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 *   list of il_simple_instruction

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 * 

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 * il_simple_instruction:

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 *   il_simple_operation       (il_simple_operation_c, il_function_call_c)

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 * | il_expression             (il_expression_c)

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 * | il_formal_funct_call      (il_formal_funct_call_c)

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 * 

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 */

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#include "flow_control_analysis.hh"

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/* set to 1 to see debug info during execution */

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static int debug = 0;

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flow_control_analysis_c::flow_control_analysis_c(symbol_c *ignore) {

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  prev_il_instruction = NULL;

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  curr_il_instruction = NULL;

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  prev_il_instruction_is_JMP_or_RET = false;

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  search_il_label = NULL;

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}

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flow_control_analysis_c::~flow_control_analysis_c(void) {

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}

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

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/* B 1.5 Program organization units */

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

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

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/* B 1.5.1 Functions */

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

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

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	search_il_label = new search_il_label_c(symbol);

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	if (debug) printf("Doing flow control analysis in body of function %s\n", ((token_c *)(symbol->derived_function_name))->value);

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

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	delete search_il_label;

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	search_il_label = NULL;

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	return NULL;

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}

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

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/* B 1.5.2 Function blocks */

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

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

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	search_il_label = new search_il_label_c(symbol);

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	if (debug) printf("Doing flow control analysis in body of FB %s\n", ((token_c *)(symbol->fblock_name))->value);

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

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	delete search_il_label;

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	search_il_label = NULL;

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	return NULL;

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}

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

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/* B 1.5.3 Programs */

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

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

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	search_il_label = new search_il_label_c(symbol);

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	if (debug) printf("Doing flow control analysis in body of program %s\n", ((token_c *)(symbol->program_type_name))->value);

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

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	delete search_il_label;

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	search_il_label = NULL;

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	return NULL;

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}

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

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/* B 1.7 Configuration elements */

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

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void *flow_control_analysis_c::visit(configuration_declaration_c *symbol) {

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	return NULL;

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}

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

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/* B.2 - Language IL (Instruction List) */

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

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

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/* B 2.1 Instructions and Operands */

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

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/*| instruction_list il_instruction */

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// SYM_LIST(instruction_list_c)

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void *flow_control_analysis_c::visit(instruction_list_c *symbol) {

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	prev_il_instruction_is_JMP_or_RET = false;

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	for(int i = 0; i < symbol->n; i++) {

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		prev_il_instruction = NULL;

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		if (i > 0) prev_il_instruction = symbol->elements[i-1];

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		curr_il_instruction = symbol->elements[i];

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		curr_il_instruction->accept(*this);

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		curr_il_instruction = NULL;

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	}

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	return NULL;

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}

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/* | label ':' [il_incomplete_instruction] eol_list */

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// SYM_REF2(il_instruction_c, label, il_instruction)

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// void *visit(instruction_list_c *symbol);

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void *flow_control_analysis_c::visit(il_instruction_c *symbol) {

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	if ((NULL != prev_il_instruction) && (!prev_il_instruction_is_JMP_or_RET))

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		/* We try to guarantee that the previous il instruction that is in the previous line, will occupy the first element of the vector.

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		 * In order to do that, we use insert() instead of push_back()

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		 */

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	/* check if it is an il_expression_c, a JMP[C[N]], or a RET, and if so, handle it correctly */

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	prev_il_instruction_is_JMP_or_RET = false;

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	if (NULL != symbol->il_instruction)

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

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	return NULL;

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}

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/* | il_simple_operator [il_operand] */

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// SYM_REF2(il_simple_operation_c, il_simple_operator, il_operand)

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// void *flow_control_analysis_c::visit(il_simple_operation_c *symbol)

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/* | function_name [il_operand_list] */

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/* NOTE: The parameters 'called_function_declaration' and 'extensible_param_count' are used to pass data between the stage 3 and stage 4. */

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// SYM_REF2(il_function_call_c, function_name, il_operand_list, symbol_c *called_function_declaration; int extensible_param_count;)

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// void *flow_control_analysis_c::visit(il_function_call_c *symbol) 

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/* | il_expr_operator '(' [il_operand] eol_list [simple_instr_list] ')' */

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// SYM_REF3(il_expression_c, il_expr_operator, il_operand, simple_instr_list);

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void *flow_control_analysis_c::visit(il_expression_c *symbol) {

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	if(NULL == symbol->simple_instr_list) 

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		/* nothing to do... */

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		return NULL;

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	symbol_c *save_prev_il_instruction = prev_il_instruction;

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	prev_il_instruction = symbol->il_operand;

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

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	prev_il_instruction = save_prev_il_instruction;

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	return NULL;

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}

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/*  il_jump_operator label */

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// SYM_REF2(il_jump_operation_c, il_jump_operator, label)

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void *flow_control_analysis_c::visit(il_jump_operation_c *symbol) {

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  /* search for the il_instruction_c containing the label */

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  il_instruction_c *destination = search_il_label->find_label(symbol->label);

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  /* give the visit(JMP_operator *) an oportunity to set the prev_il_instruction_is_JMP_or_RET flag! */

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

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  if (NULL != destination)

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  return NULL;

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}

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/*   il_call_operator prev_declared_fb_name

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 * | il_call_operator prev_declared_fb_name '(' ')'

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 * | il_call_operator prev_declared_fb_name '(' eol_list ')'

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 * | il_call_operator prev_declared_fb_name '(' il_operand_list ')'

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 * | il_call_operator prev_declared_fb_name '(' eol_list il_param_list ')'

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 */

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/* NOTE: The parameter 'called_fb_declaration'is used to pass data between stage 3 and stage4 (although currently it is not used in stage 4 */

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// SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list, symbol_c *called_fb_declaration)

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// void *flow_control_analysis_c::visit(il_fb_call_c *symbol)

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/* | function_name '(' eol_list [il_param_list] ')' */

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/* NOTE: The parameter 'called_function_declaration' is used to pass data between the stage 3 and stage 4. */

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// SYM_REF2(il_formal_funct_call_c, function_name, il_param_list, symbol_c *called_function_declaration; int extensible_param_count;)

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// void *flow_control_analysis_c::visit(il_formal_funct_call_c *symbol)

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//  void *visit(il_operand_list_c *symbol);

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void *flow_control_analysis_c::visit(simple_instr_list_c *symbol) {

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	for(int i = 0; i < symbol->n; i++) {

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		/* The prev_il_instruction for element[0] was set in visit(il_expression_c *) */

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		if (i>0) prev_il_instruction = symbol->elements[i-1];

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		symbol->elements[i]->accept(*this);

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	}

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	return NULL;

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}

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// SYM_REF1(il_simple_instruction_c, il_simple_instruction, symbol_c *prev_il_instruction;)

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void *flow_control_analysis_c::visit(il_simple_instruction_c*symbol) {

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	if (NULL != prev_il_instruction)

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		/* We try to guarantee that the previous il instruction that is in the previous line, will occupy the first element of the vector.

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		 * In order to do that, we use insert() instead of push_back()

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		 */

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	return NULL;

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}

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/*

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    void *visit(il_param_list_c *symbol);

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    void *visit(il_param_assignment_c *symbol);

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    void *visit(il_param_out_assignment_c *symbol);

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 */

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

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/* B 2.2 Operators */

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

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// void *visit(   LD_operator_c *symbol);

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// void *visit(  LDN_operator_c *symbol);

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// void *visit(   ST_operator_c *symbol);

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// void *visit(  STN_operator_c *symbol);

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// void *visit(  NOT_operator_c *symbol);

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// void *visit(    S_operator_c *symbol);

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// void *visit(    R_operator_c *symbol);

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// void *visit(   S1_operator_c *symbol);

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// void *visit(   R1_operator_c *symbol);

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// void *visit(  CLK_operator_c *symbol);

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// void *visit(   CU_operator_c *symbol);

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// void *visit(   CD_operator_c *symbol);

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// void *visit(   PV_operator_c *symbol);

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// void *visit(   IN_operator_c *symbol);

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// void *visit(   PT_operator_c *symbol);

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// void *visit(  AND_operator_c *symbol);

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// void *visit(   OR_operator_c *symbol);

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// void *visit(  XOR_operator_c *symbol);

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// void *visit( ANDN_operator_c *symbol);

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// void *visit(  ORN_operator_c *symbol);

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// void *visit( XORN_operator_c *symbol);

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// void *visit(  ADD_operator_c *symbol);

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// void *visit(  SUB_operator_c *symbol);

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// void *visit(  MUL_operator_c *symbol);

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// void *visit(  DIV_operator_c *symbol);

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// void *visit(  MOD_operator_c *symbol);

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// void *visit(   GT_operator_c *symbol);

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// void *visit(   GE_operator_c *symbol);

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// void *visit(   EQ_operator_c *symbol);

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// void *visit(   LT_operator_c *symbol);

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// void *visit(   LE_operator_c *symbol);

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// void *visit(   NE_operator_c *symbol);

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// void *visit(  CAL_operator_c *symbol);

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// void *visit( CALC_operator_c *symbol);

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// void *visit(CALCN_operator_c *symbol);

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/* this next visit function will be called directly from visit(il_instruction_c *) */

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void *flow_control_analysis_c::visit(  RET_operator_c *symbol) {

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	prev_il_instruction_is_JMP_or_RET = true;

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	return NULL;

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}

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// void *visit( RETC_operator_c *symbol);

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// void *visit(RETCN_operator_c *symbol);

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/* this next visit function will be called from visit(il_jump_operation_c *) */

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void *flow_control_analysis_c::visit(  JMP_operator_c *symbol) {

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	prev_il_instruction_is_JMP_or_RET = true;

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	return NULL;

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}

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// void *visit( JMPC_operator_c *symbol);

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// void *visit(JMPCN_operator_c *symbol);

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/* Symbol class handled together with function call checks */

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// void *visit(il_assign_operator_c *symbol, variable_name);

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/* Symbol class handled together with function call checks */

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// void *visit(il_assign_operator_c *symbol, option, variable_name);

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