256 // the program.
257
258 // ------------------------------------------------------------------
259 // ciTypeFlow::StateVector::type_meet
260 //
261 // Meet two types.
262 //
263 // The semi-lattice of types use by this analysis are modeled on those
264 // of the verifier. The lattice is as follows:
265 //
266 // top_type() >= all non-extremal types >= bottom_type
267 // and
268 // Every primitive type is comparable only with itself. The meet of
269 // reference types is determined by their kind: instance class,
270 // interface, or array class. The meet of two types of the same
271 // kind is their least common ancestor. The meet of two types of
272 // different kinds is always java.lang.Object.
273 ciType* ciTypeFlow::StateVector::type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer) {
274 assert(t1 != t2, "checked in caller");
275
276 if (t1->equals(top_type())) {
277 return t2;
278 } else if (t2->equals(top_type())) {
279 return t1;
280 } else if (t1->is_primitive_type() || t2->is_primitive_type()) {
281 // Special case null_type. null_type meet any reference type T
282 // is T. null_type meet null_type is null_type.
283 if (t1->equals(null_type())) {
284 if (!t2->is_primitive_type() || t2->equals(null_type())) {
285 return t2;
286 }
287 } else if (t2->equals(null_type())) {
288 if (!t1->is_primitive_type()) {
289 return t1;
290 }
291 }
292
293 // At least one of the two types is a non-top primitive type.
294 // The other type is not equal to it. Fall to bottom.
295 return bottom_type();
296 }
297
298 // Unwrap the types after gathering nullness information
299 bool never_null1 = t1->is_never_null();
300 bool never_null2 = t2->is_never_null();
301 t1 = t1->unwrap();
302 t2 = t2->unwrap();
303
304 // Both types are non-top non-primitive types. That is,
305 // both types are either instanceKlasses or arrayKlasses.
306 ciKlass* object_klass = analyzer->env()->Object_klass();
307 ciKlass* k1 = t1->as_klass();
308 ciKlass* k2 = t2->as_klass();
309 if (k1->equals(object_klass) || k2->equals(object_klass)) {
310 return object_klass;
311 } else if (!k1->is_loaded() || !k2->is_loaded()) {
312 // Unloaded classes fall to java.lang.Object at a merge.
313 return object_klass;
314 } else if (k1->is_interface() != k2->is_interface()) {
315 // When an interface meets a non-interface, we get Object;
316 // This is what the verifier does.
317 return object_klass;
318 } else if (k1->is_array_klass() || k2->is_array_klass()) {
319 // When an array meets a non-array, we get Object.
320 // When objArray meets typeArray, we also get Object.
321 // And when typeArray meets different typeArray, we again get Object.
322 // But when objArray meets objArray, we look carefully at element types.
323 if (k1->is_obj_array_klass() && k2->is_obj_array_klass()) {
611 } else {
612 push_object(element_klass);
613 }
614 }
615 }
616
617
618 // ------------------------------------------------------------------
619 // ciTypeFlow::StateVector::do_checkcast
620 void ciTypeFlow::StateVector::do_checkcast(ciBytecodeStream* str) {
621 bool will_link;
622 ciKlass* klass = str->get_klass(will_link);
623 if (!will_link) {
624 // VM's interpreter will not load 'klass' if object is NULL.
625 // Type flow after this block may still be needed in two situations:
626 // 1) C2 uses do_null_assert() and continues compilation for later blocks
627 // 2) C2 does an OSR compile in a later block (see bug 4778368).
628 pop_object();
629 do_null_assert(klass);
630 } else {
631 pop_object();
632 if (str->is_klass_never_null()) {
633 // Casting to a Q-Type contains a NULL check
634 assert(klass->is_valuetype(), "must be a value type");
635 push(outer()->mark_as_never_null(klass));
636 } else {
637 push_object(klass);
638 }
639 }
640 }
641
642 // ------------------------------------------------------------------
643 // ciTypeFlow::StateVector::do_getfield
644 void ciTypeFlow::StateVector::do_getfield(ciBytecodeStream* str) {
645 // could add assert here for type of object.
646 pop_object();
647 do_getstatic(str);
648 }
649
650 // ------------------------------------------------------------------
651 // ciTypeFlow::StateVector::do_getstatic
652 void ciTypeFlow::StateVector::do_getstatic(ciBytecodeStream* str) {
653 bool will_link;
654 ciField* field = str->get_field(will_link);
|
256 // the program.
257
258 // ------------------------------------------------------------------
259 // ciTypeFlow::StateVector::type_meet
260 //
261 // Meet two types.
262 //
263 // The semi-lattice of types use by this analysis are modeled on those
264 // of the verifier. The lattice is as follows:
265 //
266 // top_type() >= all non-extremal types >= bottom_type
267 // and
268 // Every primitive type is comparable only with itself. The meet of
269 // reference types is determined by their kind: instance class,
270 // interface, or array class. The meet of two types of the same
271 // kind is their least common ancestor. The meet of two types of
272 // different kinds is always java.lang.Object.
273 ciType* ciTypeFlow::StateVector::type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer) {
274 assert(t1 != t2, "checked in caller");
275
276 // Unwrap the types after gathering nullness information
277 bool never_null1 = t1->is_never_null();
278 bool never_null2 = t2->is_never_null();
279 t1 = t1->unwrap();
280 t2 = t2->unwrap();
281
282 if (t1->equals(top_type())) {
283 return t2;
284 } else if (t2->equals(top_type())) {
285 return t1;
286 } else if (t1->is_primitive_type() || t2->is_primitive_type()) {
287 // Special case null_type. null_type meet any reference type T
288 // is T. null_type meet null_type is null_type.
289 if (t1->equals(null_type())) {
290 if (!t2->is_primitive_type() || t2->equals(null_type())) {
291 return t2;
292 }
293 } else if (t2->equals(null_type())) {
294 if (!t1->is_primitive_type()) {
295 return t1;
296 }
297 }
298
299 // At least one of the two types is a non-top primitive type.
300 // The other type is not equal to it. Fall to bottom.
301 return bottom_type();
302 }
303
304 // Both types are non-top non-primitive types. That is,
305 // both types are either instanceKlasses or arrayKlasses.
306 ciKlass* object_klass = analyzer->env()->Object_klass();
307 ciKlass* k1 = t1->as_klass();
308 ciKlass* k2 = t2->as_klass();
309 if (k1->equals(object_klass) || k2->equals(object_klass)) {
310 return object_klass;
311 } else if (!k1->is_loaded() || !k2->is_loaded()) {
312 // Unloaded classes fall to java.lang.Object at a merge.
313 return object_klass;
314 } else if (k1->is_interface() != k2->is_interface()) {
315 // When an interface meets a non-interface, we get Object;
316 // This is what the verifier does.
317 return object_klass;
318 } else if (k1->is_array_klass() || k2->is_array_klass()) {
319 // When an array meets a non-array, we get Object.
320 // When objArray meets typeArray, we also get Object.
321 // And when typeArray meets different typeArray, we again get Object.
322 // But when objArray meets objArray, we look carefully at element types.
323 if (k1->is_obj_array_klass() && k2->is_obj_array_klass()) {
611 } else {
612 push_object(element_klass);
613 }
614 }
615 }
616
617
618 // ------------------------------------------------------------------
619 // ciTypeFlow::StateVector::do_checkcast
620 void ciTypeFlow::StateVector::do_checkcast(ciBytecodeStream* str) {
621 bool will_link;
622 ciKlass* klass = str->get_klass(will_link);
623 if (!will_link) {
624 // VM's interpreter will not load 'klass' if object is NULL.
625 // Type flow after this block may still be needed in two situations:
626 // 1) C2 uses do_null_assert() and continues compilation for later blocks
627 // 2) C2 does an OSR compile in a later block (see bug 4778368).
628 pop_object();
629 do_null_assert(klass);
630 } else {
631 ciType* type = pop_value();
632 if (klass->is_valuetype() && (str->is_klass_never_null() || type->is_never_null())) {
633 // Casting to a Q-Type contains a NULL check
634 push(outer()->mark_as_never_null(klass));
635 } else {
636 push_object(klass);
637 }
638 }
639 }
640
641 // ------------------------------------------------------------------
642 // ciTypeFlow::StateVector::do_getfield
643 void ciTypeFlow::StateVector::do_getfield(ciBytecodeStream* str) {
644 // could add assert here for type of object.
645 pop_object();
646 do_getstatic(str);
647 }
648
649 // ------------------------------------------------------------------
650 // ciTypeFlow::StateVector::do_getstatic
651 void ciTypeFlow::StateVector::do_getstatic(ciBytecodeStream* str) {
652 bool will_link;
653 ciField* field = str->get_field(will_link);
|