diff -r aad38592bdde -r c0bda77b37a0 stage3/array_range_check.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/stage3/array_range_check.cc	Wed Aug 22 16:46:17 2012 +0200
@@ -0,0 +1,322 @@
+/*
+ *  matiec - a compiler for the programming languages defined in IEC 61131-3
+ *
+ *  Copyright (C) 2009-2012  Mario de Sousa (msousa@fe.up.pt)
+ *  Copyright (C) 2012       Manuele Conti  (conti.ma@alice.it)
+ *
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * This code is made available on the understanding that it will not be
+ * used in safety-critical situations without a full and competent review.
+ */
+
+/*
+ * An IEC 61131-3 compiler.
+ *
+ * Based on the
+ * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
+ *
+ */
+
+
+/*
+ * Array Range Checking:
+ *   - Check whether array subscript values fall within the allowed range.
+ *     Note that for the checking of subscript values to work correctly, we need to have constant folding working too:
+ *     array_var[8 + 99] can not be checked without constant folding.
+ */
+
+
+#include "array_range_check.hh"
+#include <limits>  // required for std::numeric_limits<XXX>
+
+
+#define FIRST_(symbol1, symbol2) (((symbol1)->first_order < (symbol2)->first_order)   ? (symbol1) : (symbol2))
+#define  LAST_(symbol1, symbol2) (((symbol1)->last_order  > (symbol2)->last_order)    ? (symbol1) : (symbol2))
+
+#define STAGE3_ERROR(error_level, symbol1, symbol2, ...) {                                                                  \
+  if (current_display_error_level >= error_level) {                                                                         \
+    fprintf(stderr, "%s:%d-%d..%d-%d: error: ",                                                                             \
+            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\
+                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\
+    fprintf(stderr, __VA_ARGS__);                                                                                           \
+    fprintf(stderr, "\n");                                                                                                  \
+    error_count++;                                                                                                     \
+  }                                                                                                                         \
+}
+
+
+#define STAGE3_WARNING(symbol1, symbol2, ...) {                                                                             \
+    fprintf(stderr, "%s:%d-%d..%d-%d: warning: ",                                                                           \
+            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\
+                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\
+    fprintf(stderr, __VA_ARGS__);                                                                                           \
+    fprintf(stderr, "\n");                                                                                                  \
+    warning_found = true;                                                                                                   \
+}
+
+#define GET_CVALUE(dtype, symbol)             ((symbol)->const_value._##dtype.value)
+#define VALID_CVALUE(dtype, symbol)           (symbol_c::cs_const_value == (symbol)->const_value._##dtype.status)
+
+/*  The cmp_unsigned_signed function compares two numbers u and s.
+ *  It returns an integer indicating the relationship between the numbers:
+ *  - A zero value indicates that both numbers are equal.
+ *  - A value greater than zero indicates that numbers does not match and
+ *    first has a greater value.
+ *  - A value less than zero indicates that numbers does not match and
+ *    first has a lesser value.
+ */
+static inline int cmp_unsigned_signed(const uint64_t u, const int64_t s) {
+  const uint64_t INT64_MAX_uvar = INT64_MAX;
+  if (u <= INT64_MAX_uvar)
+    return ((int64_t)u - s);
+  return -1;
+}
+
+array_range_check_c::array_range_check_c(symbol_c *ignore) {
+	error_count = 0;
+	current_display_error_level = 0;
+}
+
+
+
+array_range_check_c::~array_range_check_c(void) {
+}
+
+
+
+int array_range_check_c::get_error_count() {
+	return error_count;
+}
+
+
+
+void array_range_check_c::check_dimension_count(array_variable_c *symbol) {
+	int dimension_count;
+	symbol_c *var_decl;
+
+	var_decl = search_varfb_instance_type->get_basetype_decl(symbol->subscripted_variable);
+	array_dimension_iterator_c array_dimension_iterator(var_decl);
+	for (dimension_count = 0; NULL != array_dimension_iterator.next(); dimension_count++);
+	if (dimension_count != ((list_c *)symbol->subscript_list)->n)
+		STAGE3_ERROR(0, symbol, symbol, "Number of subscripts/indexes does not match the number of subscripts/indexes in the array's declaration (array has %d indexes)", dimension_count);
+}
+
+
+
+void array_range_check_c::check_bounds(array_variable_c *symbol) {
+  list_c *l; /* the subscript_list */
+  symbol_c *var_decl;
+
+  l = (list_c *)symbol->subscript_list;
+  var_decl = search_varfb_instance_type->get_basetype_decl(symbol->subscripted_variable);
+  array_dimension_iterator_c array_dimension_iterator(var_decl);
+  for (int i =  0; i < l->n; i++) {
+    subrange_c *dimension = array_dimension_iterator.next();
+    /* mismatch between number of indexes/subscripts. This error will be caught in check_dimension_count() so we ignore it. */
+    if (NULL == dimension) 
+      return;
+
+    /* Check lower limit */
+    if ( VALID_CVALUE( int64, l->elements[i]) && VALID_CVALUE( int64, dimension->lower_limit))
+      if ( GET_CVALUE( int64, l->elements[i]) < GET_CVALUE( int64, dimension->lower_limit) )
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+
+    if ( VALID_CVALUE( int64, l->elements[i]) && VALID_CVALUE(uint64, dimension->lower_limit))
+      if ( cmp_unsigned_signed( GET_CVALUE(uint64, dimension->lower_limit), GET_CVALUE( int64, l->elements[i])) > 0 )
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+
+    if ( VALID_CVALUE(uint64, l->elements[i]) && VALID_CVALUE(uint64, dimension->lower_limit))
+      if ( GET_CVALUE(uint64, l->elements[i])   <  GET_CVALUE(uint64, dimension->lower_limit))
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+
+    if ( VALID_CVALUE(uint64, l->elements[i]) && VALID_CVALUE( int64, dimension->lower_limit))
+      if ( cmp_unsigned_signed(GET_CVALUE(uint64, l->elements[i]), GET_CVALUE( int64, dimension->lower_limit)) < 0 )
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+
+    /* Repeat the same check, now for upper limit */
+    if ( VALID_CVALUE( int64, l->elements[i]) && VALID_CVALUE( int64, dimension->upper_limit))
+      if ( GET_CVALUE( int64, l->elements[i])   >  GET_CVALUE( int64, dimension->upper_limit))
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+
+    if ( VALID_CVALUE( int64, l->elements[i]) && VALID_CVALUE(uint64, dimension->upper_limit))
+      if ( cmp_unsigned_signed( GET_CVALUE(uint64, dimension->upper_limit), GET_CVALUE( int64, l->elements[i])) < 0 )
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+
+    if ( VALID_CVALUE(uint64, l->elements[i]) && VALID_CVALUE(uint64, dimension->upper_limit))
+      if ( GET_CVALUE(uint64, l->elements[i])   >  GET_CVALUE(uint64, dimension->upper_limit))
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+      
+    if ( VALID_CVALUE(uint64, l->elements[i]) && VALID_CVALUE( int64, dimension->upper_limit))
+      if ( cmp_unsigned_signed(GET_CVALUE(uint64, l->elements[i]), GET_CVALUE( int64, dimension->upper_limit)) > 0 )
+      {STAGE3_ERROR(0, symbol, symbol, "Array access out of bounds."); continue;}
+      
+  }
+}
+
+
+
+
+
+
+
+
+
+/*************************/
+/* B.1 - Common elements */
+/*************************/
+/**********************/
+/* B.1.3 - Data types */
+/**********************/
+/********************************/
+/* B 1.3.3 - Derived data types */
+/********************************/
+
+/*  signed_integer DOTDOT signed_integer */
+/* dimension will be filled in during stage 3 (array_range_check_c) with the number of elements in this subrange */
+// SYM_REF2(subrange_c, lower_limit, upper_limit, unsigned long long int dimension)
+void *array_range_check_c::visit(subrange_c *symbol) {
+	unsigned long long int dimension = 0; // we use unsigned long long instead of uint64_t since it might just happen to be larger than uint64_t in the platform used for compiling this code!!
+
+	/* Determine the size of the array... */
+	if        (VALID_CVALUE( int64, symbol->upper_limit) && VALID_CVALUE( int64, symbol->lower_limit)) {  
+		// do the sums in such a way that no overflow is possible... even during intermediate steps used by compiler!
+		// remember that the result (dimension) is unsigned, while the operands are signed!!
+		// dimension = GET_CVALUE( int64, symbol->upper_limit) - VALID_CVALUE( int64, symbol->lower_limit);
+		if (GET_CVALUE( int64, symbol->lower_limit) >= 0) {
+			dimension = GET_CVALUE( int64, symbol->upper_limit) - GET_CVALUE( int64, symbol->lower_limit);
+		} else {
+			dimension  = -GET_CVALUE( int64, symbol->lower_limit);
+			dimension +=  GET_CVALUE( int64, symbol->upper_limit);     
+		}
+	} else if (VALID_CVALUE(uint64, symbol->upper_limit) && VALID_CVALUE(uint64, symbol->lower_limit)) {
+		dimension = GET_CVALUE(uint64, symbol->upper_limit) - GET_CVALUE(uint64, symbol->lower_limit); 
+	} else if (VALID_CVALUE(uint64, symbol->upper_limit) && VALID_CVALUE( int64, symbol->lower_limit)) {
+		if (GET_CVALUE( int64, symbol->lower_limit) >= 0) {
+			dimension = GET_CVALUE(uint64, symbol->upper_limit) - GET_CVALUE( int64, symbol->lower_limit);
+		} else {
+			unsigned long long int lower_ull;
+			lower_ull  = -GET_CVALUE( int64, symbol->lower_limit);
+			dimension  =  GET_CVALUE(uint64, symbol->upper_limit) + lower_ull;     
+			if (dimension < lower_ull)
+				STAGE3_ERROR(0, symbol, symbol, "Number of elements in array subrange exceeds maximum number of elements (%llu).", std::numeric_limits< unsigned long long int >::max());
+		}
+	} else ERROR;
+
+	/* correct value for dimension is actually ---> dimension = upper_limit - lower_limit + 1
+	 * Up to now, we have only determined dimension = upper_limit - lower_limit
+	 * We must first check whether this last increment will cause an overflow!
+	 */
+	if (dimension == std::numeric_limits< unsigned long long int >::max())
+		STAGE3_ERROR(0, symbol, symbol, "Number of elements in array subrange exceeds maximum number of elements (%llu).", std::numeric_limits< unsigned long long int >::max());
+	
+	/* correct value for dimension is actually ---> dimension = upper_limit - lower_limit + 1 */
+	dimension++; 
+	
+	symbol->dimension = dimension;
+	return NULL;
+}
+
+
+
+
+
+/* integer '(' [array_initial_element] ')' */
+/* array_initial_element may be NULL ! */
+// SYM_REF2(array_initial_elements_c, integer, array_initial_element)
+void *array_range_check_c::visit(array_initial_elements_c *symbol) {
+	if (VALID_CVALUE( int64, symbol->integer) && (GET_CVALUE( int64, symbol->integer) < 0)) 
+		ERROR; /* the IEC 61131-3 syntax guarantees that this value will never be negative! */
+
+	/* TODO: check that the total number of 'initial values' does not exceed the size of the array! */
+
+	return NULL;
+}
+
+
+
+
+
+
+
+
+
+/*********************/
+/* B 1.4 - Variables */
+/*********************/
+/*************************************/
+/* B 1.4.2 - Multi-element variables */
+/*************************************/
+void *array_range_check_c::visit(array_variable_c *symbol) {
+	check_dimension_count(symbol);
+	check_bounds(symbol);
+	return NULL;
+}
+
+
+/**************************************/
+/* B 1.5 - Program organisation units */
+/**************************************/
+/***********************/
+/* B 1.5.1 - Functions */
+/***********************/
+// SYM_REF4(function_declaration_c, derived_function_name, type_name, var_declarations_list, function_body)
+void *array_range_check_c::visit(function_declaration_c *symbol) {
+	symbol->var_declarations_list->accept(*this); // required for visiting subrange_c
+	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);
+	// search_var_instance_decl = new search_var_instance_decl_c(symbol);
+	symbol->function_body->accept(*this);
+	delete search_varfb_instance_type;
+	// delete search_var_instance_decl;
+	search_varfb_instance_type = NULL;
+	// search_var_instance_decl = NULL;
+	return NULL;
+}
+
+/*****************************/
+/* B 1.5.2 - Function blocks */
+/*****************************/
+// SYM_REF3(function_block_declaration_c, fblock_name, var_declarations, fblock_body)
+void *array_range_check_c::visit(function_block_declaration_c *symbol) {
+	symbol->var_declarations->accept(*this); // required for visiting subrange_c
+	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);
+	// search_var_instance_decl = new search_var_instance_decl_c(symbol);
+	symbol->fblock_body->accept(*this);
+	delete search_varfb_instance_type;
+	// delete search_var_instance_decl;
+	search_varfb_instance_type = NULL;
+	// search_var_instance_decl = NULL;
+	return NULL;
+}
+
+/**********************/
+/* B 1.5.3 - Programs */
+/**********************/
+// SYM_REF3(program_declaration_c, program_type_name, var_declarations, function_block_body)
+void *array_range_check_c::visit(program_declaration_c *symbol) {
+	symbol->var_declarations->accept(*this); // required for visiting subrange_c
+	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);
+	// search_var_instance_decl = new search_var_instance_decl_c(symbol);
+	symbol->function_block_body->accept(*this);
+	delete search_varfb_instance_type;
+	// delete search_var_instance_decl;
+	search_varfb_instance_type = NULL;
+	// search_var_instance_decl = NULL;
+	return NULL;
+}
+
+
+