//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;
}
/*
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::trans_to_do_while_loop(IR ** head, IR * ir)
{
IS_TRUE(head != NULL && *head != NULL, ("invalid parameter"));
if (ir->is_lab()) {
IR * t = ir;
LABEL_INFO * li = LAB_lab(ir);
while (t != NULL) {
if (IR_type(t) == IR_IF) {
if (IF_truebody(t) != NULL &&
IR_type(IF_truebody(t)) == IR_GOTO &&
is_same_label(LAB_lab(ir), GOTO_lab(IF_truebody(t)))) {
//start transform...
IR * dowhile = m_ru->new_ir(IR_DO_WHILE);
LOOP_det(dowhile) = m_ru->dup_irs(LOOP_det(t));
IR * if_stmt = t;
t = IR_next(ir);
while (t != NULL && t != if_stmt) {
IR * c = t;
t = IR_next(t);
remove(head, c);
add_next(&LOOP_body(dowhile), c);
}
IS_TRUE(t == if_stmt, ("???"));
remove(head, if_stmt);
if (IF_falsebody(if_stmt)) {
add_next(&dowhile, IF_falsebody(if_stmt));
IF_falsebody(if_stmt) = NULL;
}
insertafter(&ir, dowhile);
m_ru->free_irs(if_stmt); //free IF
remove(head, ir);
m_ru->free_irs(ir); //free LABEL
return true;
}
}
t = IR_next(t);
}
}
return false;
}
//The followed forms
// if (cond) {
//
// } else {
// IR-list
// }
//
//is replaced by
//
// if (!cond) {
// IR-list
// }
bool IR_CFS_OPT::transformIf2(IR ** head, IR * ir)
{
ASSERT(head && *head, ("invalid parameter"));
if (ir == NULL || !ir->is_if()) { return false; }
//Check true part
if (IF_truebody(ir) == NULL) {
if (IF_falsebody(ir) == NULL) {
xcom::remove(head, ir);
m_ru->freeIRTree(ir);
return true;
}
m_ru->invertCondition(&IF_det(ir));
IF_truebody(ir) = IF_falsebody(ir);
IF_falsebody(ir) = NULL;
return true;
}
return false;
}
/* The followed forms
if (cond) {
} else {
IR-list
}
is replaced by
if (!cond) {
IR-list
} */
bool IR_CFS_OPT::trans_if2(IR ** head, IR * ir)
{
IS_TRUE(head && *head, ("invalid parameter"));
if (ir == NULL || IR_type(ir) != IR_IF) { return false; }
//Check true part
if (!IF_truebody(ir)) {
if (IF_falsebody(ir) == NULL) {
remove(head, ir);
m_ru->free_irs(ir);
return true;
}
m_ru->invert_cond(&IF_det(ir));
IF_truebody(ir) = IF_falsebody(ir);
IF_falsebody(ir) = NULL;
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;
}
//The followed forms
// if (cond) {
// t=1
// a=1
// goto L1;
// }
// f=1
// goto L2;
// L1:
//
//is replaced with
//
// if (!cond) {
// f=1
// goto L2;
// }
// t=1
// a=1
// L1:
//
//'goto L1' is removed and free, and L1 is removed if it is not a target
//of some other instruction.
bool IR_CFS_OPT::transformIf1(IR ** head, IR * ir)
{
ASSERT(head && *head, ("invalid parameter"));
if (ir == NULL || !ir->is_if()) { return false; }
//Check true part.
IR * t = IF_truebody(ir);
while (t != NULL) {
if (!is_non_branch_ir(t)) {
break;
}
t = t->get_next();
}
if (t != NULL && t->get_next() == NULL && t->is_goto()) {
IR * first_goto = t;
t = ir->get_next();
while (t != NULL) {
if (!is_non_branch_ir(t)) { break; }
t = t->get_next();
}
if (t != NULL && t->is_goto()) {
IR * second_goto = t;
if (IR_next(second_goto) != NULL &&
IR_next(second_goto)->is_lab() &&
isSameLabel(GOTO_lab(first_goto),
LAB_lab(IR_next(second_goto)))) {
//Start transforming.
m_ru->invertCondition(&IF_det(ir));
IR * new_list1 = NULL;
IR * new_list2 = NULL;
t = IF_truebody(ir);
//Split true body of IF.
IR * last = NULL;
while (t != first_goto) {
IR * c = t;
t = t->get_next();
xcom::remove(&IF_truebody(ir), c);
xcom::add_next(&new_list1, &last, c);
}
ASSERT(t && t == first_goto, ("invalid control flow"));
xcom::remove(&IF_truebody(ir), first_goto);
m_ru->freeIRTree(first_goto);
//Split all irs between IF and L1.
t = ir->get_next();
while (t != second_goto) {
IR * c = t;
t = t->get_next();
xcom::remove(head, c);
xcom::add_next(&new_list2, c);
}
ASSERT(t != NULL && t == second_goto, ("???"));
xcom::remove(head, second_goto);
xcom::add_next(&new_list2, second_goto);
//Swap new_list1 and new_list2
xcom::insertbefore(&IF_truebody(ir), IF_truebody(ir), new_list2);
//Update the IR_parent for new_list2.
for (IR * tmp = new_list2; tmp != NULL; tmp = IR_next(tmp)) {
IR_parent(tmp) = ir;
}
ASSERT(IF_truebody(ir) == new_list2, ("illegal insertbefore<T>"));
xcom::insertafter(&ir, new_list1);
//Update the IR_parent for new_list1.
for (IR * tmp = new_list1; tmp != NULL; tmp = IR_next(tmp)) {
IR_parent(tmp) = IR_parent(ir);
}
return true;
}
}
}
return false;
}
bool IR_CFS_OPT::perform_cfs_optimization(IN OUT IR ** ir_list,
IN SIMP_CTX const& sc)
{
bool change = false;
for (IR * ir = *ir_list; ir != NULL;) {
if (trans_to_do_while_loop(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (IR_type(ir) == IR_IF && trans_if1(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (IR_type(ir) == IR_IF && trans_if2(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (IR_type(ir) == IR_IF && trans_if3(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
switch (IR_type(ir)) {
case IR_IF:
if (hoist_if(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (perform_cfs_optimization(&IF_truebody(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
if (perform_cfs_optimization(&IF_falsebody(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
break;
case IR_DO_WHILE:
case IR_WHILE_DO:
case IR_DO_LOOP:
if (hoist_loop(ir_list, ir)) {
change = true;
ir = *ir_list;
continue;
}
if (perform_cfs_optimization(&LOOP_body(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
break;
case IR_SWITCH:
if (perform_cfs_optimization(&SWITCH_body(ir), sc)) {
change = true;
ir = *ir_list;
continue;
}
break;
default:;
} //end switch
ir = IR_next(ir);
}
return change;
}
/* The followed forms
if (cond) {
t=1
a=1
goto L1;
}
f=1
goto L2;
L1:
is replaced by
if (!cond) {
f=1
goto L2;
}
t=1
a=1
L1:
'goto L1' is removed and free, and L1 is removed if it is not a target
of some other instruction. */
bool IR_CFS_OPT::trans_if1(IR ** head, IR * ir)
{
IS_TRUE(head && *head, ("invalid parameter"));
if (ir == NULL || IR_type(ir) != IR_IF) { return false; }
//Check true part.
IR * t = IF_truebody(ir);
while (t != NULL) {
if (!is_non_branch_ir(t)) {
break;
}
t = IR_next(t);
}
if (t != NULL && IR_next(t) == NULL && IR_type(t) == IR_GOTO) {
IR * first_goto = t;
t = IR_next(ir);
while (t != NULL) {
if (!is_non_branch_ir(t)) break;
t = IR_next(t);
}
if (t != NULL && IR_type(t) == IR_GOTO) {
IR * second_goto = t;
if (IR_next(second_goto) != NULL &&
IR_next(second_goto)->is_lab() &&
is_same_label(GOTO_lab(first_goto),
LAB_lab(IR_next(second_goto)))) {
//Here we start to transform...
m_ru->invert_cond(&IF_det(ir));
IR * new_list1 = NULL;
IR * new_list2 = NULL;
t = IF_truebody(ir);
//Split true body of IF.
IR * last = NULL;
while (t != first_goto) {
IR * c = t;
t = IR_next(t);
remove(&IF_truebody(ir), c);
add_next(&new_list1, &last, c);
}
IS_TRUE(t && t == first_goto, ("invalid control flow"));
remove(&IF_truebody(ir), first_goto);
m_ru->free_irs(first_goto);
//Split all irs between IF and L1.
t = IR_next(ir);
while (t != second_goto) {
IR * c = t;
t = IR_next(t);
remove(head, c);
add_next(&new_list2, c);
}
IS_TRUE(t != NULL && t == second_goto, ("???"));
remove(head, second_goto);
add_next(&new_list2, second_goto);
//Swap new_list1 and new_list2
insertbefore(&IF_truebody(ir), IF_truebody(ir), new_list2);
//Update the IR_parent for new_list2.
for (IR * tmp = new_list2; tmp != NULL; tmp = IR_next(tmp)) {
IR_parent(tmp) = ir;
}
IS_TRUE(IF_truebody(ir) == new_list2,
("illegal insertbefore<T>"));
insertafter(&ir, new_list1);
//Update the IR_parent for new_list1.
for (IR * tmp = new_list1; tmp != NULL; tmp = IR_next(tmp)) {
IR_parent(tmp) = IR_parent(ir);
}
return true;
}
}
}
return false;
}