void Value::set_registers(Assembler::Register low, Assembler::Register high) {
destroy();
GUARANTEE(use_two_registers(), "tag_check");
set_where(T_REGISTER);
_low = (int) low;
_high = (int) high;
}
void Value::destroy() {
if (in_register()) {
RegisterAllocator::dereference(lo_register());
if (use_two_registers()) {
RegisterAllocator::dereference(hi_register());
}
}
set_where(T_NOWHERE);
}
void Value::copy(Value& result) {
GUARANTEE(in_register(), "value must be in register");
if (use_two_registers()) {
result.set_registers(lo_register(), hi_register());
RegisterAllocator::reference(lo_register());
RegisterAllocator::reference(hi_register());
//cse
RegisterAllocator::wipe_notation_of(lo_register());
RegisterAllocator::wipe_notation_of(hi_register());
} else {
result.set_register(lo_register());
RegisterAllocator::reference(lo_register());
//cse
RegisterAllocator::wipe_notation_of(lo_register());
}
}
void Value::writable_copy(Value& result) {
GUARANTEE(in_register(), "value must be in register");
VirtualStackFrame* frame = Compiler::current()->frame();
if (use_two_registers()) {
if ((RegisterAllocator::references(lo_register()) == 1) &&
(RegisterAllocator::references(hi_register()) == 1)) {
// use this value as the writable copy.
RegisterAllocator::spill(hi_register());
RegisterAllocator::spill(lo_register());
frame->dirtify(hi_register());
frame->dirtify(lo_register());
result.set_registers(lo_register(), hi_register());
// make sure we increment the reference counters
RegisterAllocator::reference(lo_register());
RegisterAllocator::reference(hi_register());
} else {
// allocate two new registers and copy the value of these registers into it.
result.set_registers(RegisterAllocator::allocate(), RegisterAllocator::allocate());
Compiler::code_generator()->move(result, *this);
}
} else {
if (RegisterAllocator::references(lo_register()) == 1) {
// use this value as the writable copy.
RegisterAllocator::spill(lo_register());
frame->dirtify(lo_register());
result.set_register(lo_register());
// make sure we increment the reference counter
RegisterAllocator::reference(lo_register());
} else {
// allocate a new register and copy the value of this register into it.
result.assign_register();
Compiler::code_generator()->move(result, *this);
}
}
}
Assembler::Register hi_register( void ) const {
GUARANTEE(use_two_registers(), "must be a two-register value");
return (Assembler::Register)_high;
}