diff -r 835697564c6d -r e22150ad75fd stage3/flow_control_analysis.cc --- a/stage3/flow_control_analysis.cc Wed Mar 14 11:31:07 2012 +0000 +++ b/stage3/flow_control_analysis.cc Wed Mar 14 19:31:17 2012 +0000 @@ -38,11 +38,19 @@ * prev_il_instruction variable in the il_instruction_c, so it points to * the previous il_instruction_c object in the instruction list instruction_list_c. * - * The result will essentially be a linked list of il_instruction_c objects, each + * Since IL code can contain jumps (JMP), the same il_instruction may effectively have + * several previous il_instructions. In order to accommodate this, each il_instruction + * will maintain a vector (i..e an array) of pointers to all the previous il_instructions. + * We do however attempt to guarantee that the first element in the vector (array) will preferentially + * point to the il instruction that is right before / imediately preceding the current il instructions, + * i.e. the first element in the array will tend to point to the previous il_instruction + * that is not a jump JMP IL instruction! + * + * The result will essentially be a graph of il_instruction_c objects, each * pointing to the previous il_instruction_c object. * * The reality is we will get several independent and isolated linked lists - * (actually, once we process labels correctly, this will become a graph): + * (actually, since we now process labels correctly, this is really a graph): * one for each block of IL code (e.g. inside a Function, FB or Program). * Additionally, when the IL code has an expression (expression_c object), we will actually * have one more isolated linked list for the IL code inside that expression. @@ -196,7 +204,10 @@ // void *visit(instruction_list_c *symbol); void *flow_control_analysis_c::visit(il_instruction_c *symbol) { if ((NULL != prev_il_instruction) && (!prev_il_instruction_is_JMP_or_RET)) - symbol->prev_il_instruction.push_back(prev_il_instruction); + /* We try to guarantee that the previous il instruction that is in the previous line, will occupy the first element of the vector. + * In order to do that, we use insert() instead of push_back() + */ + symbol->prev_il_instruction.insert(symbol->prev_il_instruction.begin() , prev_il_instruction); /* check if it is an il_expression_c, a JMP[C[N]], or a RET, and if so, handle it correctly */ prev_il_instruction_is_JMP_or_RET = false; @@ -281,7 +292,10 @@ // SYM_REF1(il_simple_instruction_c, il_simple_instruction, symbol_c *prev_il_instruction;) void *flow_control_analysis_c::visit(il_simple_instruction_c*symbol) { if (NULL != prev_il_instruction) - symbol->prev_il_instruction.push_back(prev_il_instruction); + /* We try to guarantee that the previous il instruction that is in the previous line, will occupy the first element of the vector. + * In order to do that, we use insert() instead of push_back() + */ + symbol->prev_il_instruction.insert(symbol->prev_il_instruction.begin() , prev_il_instruction); return NULL; }