//Control flow struct optimizations.
//Transform follow struct to do-while loop
//
// LABEL:
// IR-List
// IF DET
// GOTO LABEL
// ...(DEAD CODE)
// ELSE
// FALSE-PART
// ENDIF
//
//is replace by
//
// DO {
// IR-List
// } WHILE DET
// FALSE-PART
bool IR_CFS_OPT::transformToDoWhile(IR ** head, IR * ir)
{
ASSERT(head != NULL && *head != NULL, ("invalid parameter"));
if (!ir->is_lab()) { return false; }
for (IR * t = ir; t != NULL; t = t->get_next()) {
if (!t->is_if()) { continue; }
if (IF_truebody(t) != NULL &&
IF_truebody(t)->is_goto() &&
isSameLabel(LAB_lab(ir), GOTO_lab(IF_truebody(t)))) {
//Start transform.
IR * dowhile = m_ru->allocIR(IR_DO_WHILE);
LOOP_det(dowhile) = m_ru->dupIRTree(LOOP_det(t));
IR * if_stmt = t;
t = ir->get_next();
while (t != NULL && t != if_stmt) {
IR * c = t;
t = t->get_next();
xcom::remove(head, c);
xcom::add_next(&LOOP_body(dowhile), c);
}
ASSERT(t == if_stmt, ("illegal IR layout"));
xcom::remove(head, if_stmt);
if (IF_falsebody(if_stmt)) {
xcom::add_next(&dowhile, IF_falsebody(if_stmt));
IF_falsebody(if_stmt) = NULL;
}
xcom::insertafter(&ir, dowhile);
m_ru->freeIRTree(if_stmt); //free IF
xcom::remove(head, ir);
m_ru->freeIRTree(ir); //free LABEL
return true;
}
}
return false;
}
bool IR_CFS_OPT::CfsOpt(
IN OUT IR ** ir_list,
SimpCtx const& sc)
{
bool change = false;
for (IR * ir = *ir_list; ir != NULL;) {
if (transformToDoWhile(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (ir->is_if() && transformIf1(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (ir->is_if() && transformIf2(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (ir->is_if() && transformIf3(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
switch (ir->get_code()) {
case IR_IF:
if (hoistIf(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (CfsOpt(&IF_truebody(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
if (CfsOpt(&IF_falsebody(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
break;
case IR_DO_WHILE:
case IR_WHILE_DO:
case IR_DO_LOOP:
if (hoistLoop(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (CfsOpt(&LOOP_body(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
break;
case IR_SWITCH:
if (CfsOpt(&SWITCH_body(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
break;
default:;
} //end switch
ir = ir->get_next();
}
return change;
}