--- a/stage3/fill_candidate_datatypes.cc Sun Feb 19 16:16:45 2012 +0000
+++ b/stage3/fill_candidate_datatypes.cc Mon Feb 20 15:24:26 2012 +0000
@@ -287,11 +287,20 @@
return;
}
+ /* The value being passed to the 'param_name' parameter is actually the prev_il_instruction.
+ * However, we do not place that object directly in the fake il_param_list_c that we will be
+ * creating, since the visit(il_fb_call_c *) method will recursively call every object in that list.
+ * The il_prev_intruction object has already been visited. We DO NOT want to visit it again.
+ * The easiest way to work around this is to simply use a new object, and copy the relevant details to that object!
+ */
+ symbol_c param_value;
+ copy_candidate_datatype_list(prev_il_instruction/*from*/, ¶m_value/*to*/);
+
identifier_c variable_name(param_name);
// SYM_REF1(il_assign_operator_c, variable_name)
il_assign_operator_c il_assign_operator(&variable_name);
// SYM_REF3(il_param_assignment_c, il_assign_operator, il_operand, simple_instr_list)
- il_param_assignment_c il_param_assignment(&il_assign_operator, prev_il_instruction/*il_operand*/, NULL);
+ il_param_assignment_c il_param_assignment(&il_assign_operator, ¶m_value/*il_operand*/, NULL);
il_param_list_c il_param_list;
il_param_list.add_element(&il_param_assignment);
// SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list, symbol_c *called_fb_declaration)
@@ -812,8 +821,11 @@
// void *visit(instruction_list_c *symbol);
void *fill_candidate_datatypes_c::visit(il_instruction_c *symbol) {
if (NULL == symbol->il_instruction) {
- /* This object has (inherits) the same candidate datatypes as the prev_il_instruction */
- copy_candidate_datatype_list(symbol->prev_il_instruction /*from*/, symbol /*to*/);
+ /* This empty/null il_instruction does not change the value of the current/default IL variable.
+ * So it inherits the candidate_datatypes from it's previous IL instructions!
+ */
+ if (NULL != symbol->prev_il_instruction)
+ copy_candidate_datatype_list(symbol->prev_il_instruction /*from*/, symbol /*to*/);
} else {
prev_il_instruction = symbol->prev_il_instruction;
symbol->il_instruction->accept(*this);
@@ -947,6 +959,9 @@
*/
symbol->called_fb_declaration = fb_decl;
+ /* This object has the same candidate datatypes as the prev_il_instruction, since it does not change the value stored in the current/default IL variable. */
+ copy_candidate_datatype_list(prev_il_instruction/*from*/, symbol/*to*/);
+
if (debug) std::cout << "FB [] ==> " << symbol->candidate_datatypes.size() << " result.\n";
return NULL;
}
--- a/stage3/narrow_candidate_datatypes.cc Sun Feb 19 16:16:45 2012 +0000
+++ b/stage3/narrow_candidate_datatypes.cc Mon Feb 20 15:24:26 2012 +0000
@@ -123,13 +123,13 @@
* may actually be calling an object of the il_instruction_c class.
* If that is the case, that same il_instruction_c object will be called again inside the for() loop
* of void *narrow_candidate_datatypes_c::visit(instruction_list_c *symbol);
- * This is actually safe, as the narrow algorithm for all IL instructions is idem-potent.
- * (It is easier to just let it be called twice than to hack the code to guarantee that it is
- * only called once - this would also make this hacked code ugly an un-elegant, so we leave
- * it as it is for now...)
+ * Since this is not safe (the prev_il_instruction variable will be overwritten with a wrong value!),
+ * we only do the recursive call if this parameter does not point to a il_instruction_c object.
+ * Actually, it is easier to check whether it is not the same as the prev_il_instruction.
*/
set_datatype(desired_datatype, call_param_value);
- call_param_value->accept(*this);
+ if (call_param_value != prev_il_instruction)
+ call_param_value->accept(*this);
if (NULL != param_name)
if (extensible_parameter_highest_index < fp_iterator.extensible_param_index())
@@ -179,8 +179,15 @@
if ((NULL != param_name) && (NULL == desired_datatype)) ERROR;
if ((NULL == param_name) && (NULL != desired_datatype)) ERROR;
+ /* set the desired data type for this parameter */
set_datatype(desired_datatype, call_param_value);
- call_param_value->accept(*this);
+ /* And recursively call that parameter/expression, so it can propagate that info */
+ /* However, when handling an implicit IL FB call, the first parameter is fake, and points to the prev_il_instruction.
+ * In this case, we do not propagate this info down, as that prev_il_instruction will be called later
+ * (remember, we iterate backwards through the IL instructions) by the for() loop in the instruction_list_c.
+ */
+ if (call_param_value != prev_il_instruction)
+ call_param_value->accept(*this);
if (NULL != param_name)
if (extensible_parameter_highest_index < fp_iterator.extensible_param_index())
@@ -441,7 +448,9 @@
/*| instruction_list il_instruction */
// SYM_LIST(instruction_list_c)
void *narrow_candidate_datatypes_c::visit(instruction_list_c *symbol) {
- /* We need to go through the instructions backwards, so we can not use the base class' visitor */
+ /* In order to execute the narrow algoritm correctly, we need to go through the instructions backwards,
+ * so we can not use the base class' visitor
+ */
for(int i = symbol->n-1; i >= 0; i--) {
symbol->elements[i]->accept(*this);
}
@@ -457,41 +466,14 @@
if (NULL != symbol->prev_il_instruction)
symbol->prev_il_instruction->datatype = symbol->datatype;
} else {
- prev_il_instruction = symbol->prev_il_instruction;
/* Tell the il_instruction the datatype that it must generate - this was chosen by the next il_instruction (remember: we are iterating backwards!) */
symbol->il_instruction->datatype = symbol->datatype;
+ prev_il_instruction = symbol->prev_il_instruction;
symbol->il_instruction->accept(*this);
- }
- return NULL;
-}
-
-
-
-
-/*************************************************************************************************/
-/* Important NOTE: */
-/* */
-/* The visit() methods for all the IL instructions must be idem-potent, as they may */
-/* potentially be called twice to narrow the same object. In other words, they may be called */
-/* to narrow an object that has already been previously narrowed. */
-/* This occurs when that IL instruction imediately precedes an IL non-formal function */
-/* invocation: */
-/* LD 45.5 */
-/* SIN */
-/* */
-/* In the above case, 'LD 45.5' will be narrowed once when the code that handles the */
-/* SIN function call */
-/* */
-/* narrow_nonformal_call(...), which is called by narrow_function_invocation(...), which is */
-/* in turn called by visit(il_function_call_c *) */
-/* */
-/* calls the call_param_value->accept(*this), where call_param_value will be a pointer */
-/* to the preceding IL instruction (in the above case, 'LD 45.5'). */
-/* */
-/* That same IL instruction will be again narrowed when called by the for() loop in */
-/* the visit(instruction_list_c *) visitor method. */
-/*************************************************************************************************/
-
+ prev_il_instruction = NULL;
+ }
+ return NULL;
+}
@@ -529,8 +511,7 @@
* the following code is actually correct!
*/
narrow_function_invocation(symbol, fcall_param);
- /* set the desired datatype of the previous il instruction */
- prev_il_instruction->datatype = symbol->datatype;
+ /* The desired datatype of the previous il instruction was already set by narrow_function_invocation() */
return NULL;
}
@@ -574,7 +555,8 @@
* If we were to have the following line of code after calling arrow_[non]formal_call(),
* we would then be overwriting the datatype with the wrong value!
*/
- prev_il_instruction->datatype = symbol->datatype;
+ if (NULL != prev_il_instruction)
+ prev_il_instruction->datatype = symbol->datatype;
/* Note: We do not use the symbol->called_fb_declaration value (set in fill_candidate_datatypes_c)
* because we try to identify any other datatype errors in the expressions used in the
@@ -597,6 +579,29 @@
if (NULL != symbol->il_operand_list) narrow_nonformal_call(symbol, fb_decl);
if (NULL != symbol-> il_param_list) narrow_formal_call(symbol, fb_decl);
+ /* NOTE:
+ * When handling these implicit IL calls, the parameter_value being passed to the FB parameter
+ * (in the previous example, the 'CU' parameter) is actually the prev_il_instruction.
+ * In this case, the prev_il_instruction->datatype will be set by the narrow_[non]formal_call(),
+ * using the param_value pointer to this same object.
+ *
+ * We must check that the datatype required by the IL instructions following this FB call
+ * is the same as that required for the first parameter. If not, then we have a semantic error,
+ * and we set it to NULL.
+ *
+ * However, we only do that if:
+ * - There really exists an il_prev_instruction
+ * (if it does not exist, it will be a semantic error. But that will be caught by the print_datatypes_error_c)
+ * - The IL instruction that comes after this IL FB call actually asked this FB call for a specific
+ * datatype in the current/default vairable, once this IL FB call returns.
+ * However, sometimes, (for e.g., this FB call is the last in the IL list) the subsequent FB to not aks this
+ * FB call for any datatype. In that case, then the datatype required to pass to the first parameter of the
+ * FB call must be left unchanged!
+ */
+ if ((NULL != prev_il_instruction) && (NULL != symbol->datatype))
+ if (!is_type_equal(prev_il_instruction->datatype, symbol->datatype)) {
+ prev_il_instruction->datatype = NULL;
+ }
return NULL;
}
@@ -616,8 +621,7 @@
};
narrow_function_invocation(symbol, fcall_param);
- /* set the desired datatype of the previous il instruction */
- prev_il_instruction->datatype = symbol->datatype;
+ /* The desired datatype of the previous il instruction was already set by narrow_function_invocation() */
return NULL;
}