1 /*
2 * Copyright (c) 1998, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "compiler/compileLog.hpp"
26 #include "interpreter/linkResolver.hpp"
27 #include "memory/universe.hpp"
28 #include "oops/flatArrayKlass.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/castnode.hpp"
32 #include "opto/inlinetypenode.hpp"
33 #include "opto/memnode.hpp"
34 #include "opto/parse.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/runtime.hpp"
37 #include "opto/subnode.hpp"
38 #include "runtime/deoptimization.hpp"
39 #include "runtime/handles.inline.hpp"
40
41 //=============================================================================
42 // Helper methods for _get* and _put* bytecodes
43 //=============================================================================
44
45 void Parse::do_field_access(bool is_get, bool is_field) {
46 bool will_link;
47 ciField* field = iter().get_field(will_link);
48 assert(will_link, "getfield: typeflow responsibility");
49
50 ciInstanceKlass* field_holder = field->holder();
51
52 if (is_get && is_field && field_holder->is_inlinetype() && peek()->is_InlineType()) {
53 InlineTypeNode* vt = peek()->as_InlineType();
54 null_check(vt);
55 Node* value = vt->field_value_by_offset(field->offset_in_bytes());
56 if (value->is_InlineType()) {
57 value = value->as_InlineType()->adjust_scalarization_depth(this);
58 }
59 pop();
60 push_node(field->layout_type(), value);
61 return;
62 }
63
64 if (is_field == field->is_static()) {
65 // Interpreter will throw java_lang_IncompatibleClassChangeError
66 // Check this before allowing <clinit> methods to access static fields
67 uncommon_trap(Deoptimization::Reason_unhandled,
68 Deoptimization::Action_none);
69 return;
70 }
71
72 // Deoptimize on putfield writes to call site target field outside of CallSite ctor.
73 if (!is_get && field->is_call_site_target() &&
74 !(method()->holder() == field_holder && method()->is_object_constructor())) {
75 uncommon_trap(Deoptimization::Reason_unhandled,
76 Deoptimization::Action_reinterpret,
77 nullptr, "put to call site target field");
78 return;
79 }
80
81 if (C->needs_clinit_barrier(field, method())) {
82 clinit_barrier(field_holder, method());
83 if (stopped()) return;
84 }
85
86 assert(field->will_link(method(), bc()), "getfield: typeflow responsibility");
87
88 // Note: We do not check for an unloaded field type here any more.
89
90 // Generate code for the object pointer.
91 Node* obj;
92 if (is_field) {
93 int obj_depth = is_get ? 0 : field->type()->size();
94 obj = null_check(peek(obj_depth));
95 // Compile-time detect of null-exception?
96 if (stopped()) return;
97
98 #ifdef ASSERT
99 const TypeInstPtr *tjp = TypeInstPtr::make(TypePtr::NotNull, iter().get_declared_field_holder());
100 assert(_gvn.type(obj)->higher_equal(tjp), "cast_up is no longer needed");
101 #endif
102
103 if (is_get) {
104 (void) pop(); // pop receiver before getting
105 do_get_xxx(obj, field);
106 } else {
107 do_put_xxx(obj, field, is_field);
108 if (stopped()) {
109 return;
110 }
111 (void) pop(); // pop receiver after putting
112 }
113 } else {
114 const TypeInstPtr* tip = TypeInstPtr::make(field_holder->java_mirror());
115 obj = _gvn.makecon(tip);
116 if (is_get) {
117 do_get_xxx(obj, field);
118 } else {
119 do_put_xxx(obj, field, is_field);
120 }
121 }
122 }
123
124 void Parse::do_get_xxx(Node* obj, ciField* field) {
125 BasicType bt = field->layout_type();
126 // Does this field have a constant value? If so, just push the value.
127 if (field->is_constant() && !field->is_flat() &&
128 // Keep consistent with types found by ciTypeFlow: for an
129 // unloaded field type, ciTypeFlow::StateVector::do_getstatic()
130 // speculates the field is null. The code in the rest of this
131 // method does the same. We must not bypass it and use a non
132 // null constant here.
133 (bt != T_OBJECT || field->type()->is_loaded())) {
134 // final or stable field
135 Node* con = make_constant_from_field(field, obj);
136 if (con != nullptr) {
137 push_node(field->layout_type(), con);
138 return;
139 }
140 }
141
142 ciType* field_klass = field->type();
143 field_klass = improve_abstract_inline_type_klass(field_klass);
144 int offset = field->offset_in_bytes();
145 bool must_assert_null = false;
146
147 Node* ld = nullptr;
148 if (field->is_null_free() && field_klass->as_inline_klass()->is_empty()) {
149 // Loading from a field of an empty inline type. Just return the default instance.
150 ld = InlineTypeNode::make_all_zero(_gvn, field_klass->as_inline_klass());
151 } else if (field->is_flat()) {
152 // Loading from a flat inline type field.
153 ciInlineKlass* vk = field->type()->as_inline_klass();
154 bool is_naturally_atomic = field->is_null_free() && vk->nof_declared_nonstatic_fields() <= 1;
155 bool needs_atomic_access = (!field->is_null_free() || field->is_volatile()) && !is_naturally_atomic;
156 ld = InlineTypeNode::make_from_flat(this, field_klass->as_inline_klass(), obj, obj, nullptr, field->holder(), offset, needs_atomic_access, field->null_marker_offset());
157 } else {
158 // Build the resultant type of the load
159 const Type* type;
160 if (is_reference_type(bt)) {
161 if (!field_klass->is_loaded()) {
162 type = TypeInstPtr::BOTTOM;
163 must_assert_null = true;
164 } else if (field->is_static_constant()) {
165 // This can happen if the constant oop is non-perm.
166 ciObject* con = field->constant_value().as_object();
167 // Do not "join" in the previous type; it doesn't add value,
168 // and may yield a vacuous result if the field is of interface type.
169 if (con->is_null_object()) {
170 type = TypePtr::NULL_PTR;
171 } else {
172 type = TypeOopPtr::make_from_constant(con)->isa_oopptr();
173 }
174 assert(type != nullptr, "field singleton type must be consistent");
175 } else {
176 type = TypeOopPtr::make_from_klass(field_klass->as_klass());
177 if (field->is_null_free()) {
178 type = type->join_speculative(TypePtr::NOTNULL);
179 }
180 }
181 } else {
182 type = Type::get_const_basic_type(bt);
183 }
184 Node* adr = basic_plus_adr(obj, obj, offset);
185 const TypePtr* adr_type = C->alias_type(field)->adr_type();
186 DecoratorSet decorators = IN_HEAP;
187 decorators |= field->is_volatile() ? MO_SEQ_CST : MO_UNORDERED;
188 ld = access_load_at(obj, adr, adr_type, type, bt, decorators);
189 if (field_klass->is_inlinetype()) {
190 // Load a non-flattened inline type from memory
191 ld = InlineTypeNode::make_from_oop(this, ld, field_klass->as_inline_klass());
192 }
193 }
194
195 // Adjust Java stack
196 if (type2size[bt] == 1)
197 push(ld);
198 else
199 push_pair(ld);
200
201 if (must_assert_null) {
202 // Do not take a trap here. It's possible that the program
203 // will never load the field's class, and will happily see
204 // null values in this field forever. Don't stumble into a
205 // trap for such a program, or we might get a long series
206 // of useless recompilations. (Or, we might load a class
207 // which should not be loaded.) If we ever see a non-null
208 // value, we will then trap and recompile. (The trap will
209 // not need to mention the class index, since the class will
210 // already have been loaded if we ever see a non-null value.)
211 // uncommon_trap(iter().get_field_signature_index());
212 if (PrintOpto && (Verbose || WizardMode)) {
213 method()->print_name(); tty->print_cr(" asserting nullness of field at bci: %d", bci());
214 }
215 if (C->log() != nullptr) {
216 C->log()->elem("assert_null reason='field' klass='%d'",
217 C->log()->identify(field_klass));
218 }
219 // If there is going to be a trap, put it at the next bytecode:
220 set_bci(iter().next_bci());
221 null_assert(peek());
222 set_bci(iter().cur_bci()); // put it back
223 }
224 }
225
226 // If the field klass is an abstract value klass (for which we do not know the layout, yet), it could have a unique
227 // concrete sub klass for which we have a fixed layout. This allows us to use InlineTypeNodes instead.
228 ciType* Parse::improve_abstract_inline_type_klass(ciType* field_klass) {
229 Dependencies* dependencies = C->dependencies();
230 if (UseUniqueSubclasses && dependencies != nullptr && field_klass->is_instance_klass()) {
231 ciInstanceKlass* instance_klass = field_klass->as_instance_klass();
232 if (instance_klass->is_loaded() && instance_klass->is_abstract_value_klass()) {
233 ciInstanceKlass* sub_klass = instance_klass->unique_concrete_subklass();
234 if (sub_klass != nullptr && sub_klass != field_klass) {
235 field_klass = sub_klass;
236 dependencies->assert_abstract_with_unique_concrete_subtype(instance_klass, sub_klass);
237 }
238 }
239 }
240 return field_klass;
241 }
242
243 void Parse::do_put_xxx(Node* obj, ciField* field, bool is_field) {
244 bool is_vol = field->is_volatile();
245 int offset = field->offset_in_bytes();
246 BasicType bt = field->layout_type();
247 Node* val = type2size[bt] == 1 ? pop() : pop_pair();
248
249 if (field->is_null_free()) {
250 PreserveReexecuteState preexecs(this);
251 jvms()->set_should_reexecute(true);
252 inc_sp(1);
253 val = null_check(val);
254 if (stopped()) {
255 return;
256 }
257 }
258 if (obj->is_InlineType()) {
259 set_inline_type_field(obj, field, val);
260 return;
261 }
262 if (field->is_null_free() && field->type()->as_inline_klass()->is_empty() && (!method()->is_object_constructor() || field->is_flat())) {
263 // Storing to a field of an empty, null-free inline type that is already initialized. Ignore.
264 return;
265 } else if (field->is_flat()) {
266 // Storing to a flat inline type field.
267 ciInlineKlass* vk = field->type()->as_inline_klass();
268 if (!val->is_InlineType()) {
269 assert(gvn().type(val) == TypePtr::NULL_PTR, "Unexpected value");
270 val = InlineTypeNode::make_null(gvn(), vk);
271 }
272 inc_sp(1);
273 bool is_naturally_atomic = field->is_null_free() && vk->nof_declared_nonstatic_fields() <= 1;
274 bool needs_atomic_access = (!field->is_null_free() || field->is_volatile()) && !is_naturally_atomic;
275 val->as_InlineType()->store_flat(this, obj, obj, nullptr, field->holder(), offset, needs_atomic_access, field->null_marker_offset(), IN_HEAP | MO_UNORDERED);
276 dec_sp(1);
277 } else {
278 // Store the value.
279 const Type* field_type;
280 if (!field->type()->is_loaded()) {
281 field_type = TypeInstPtr::BOTTOM;
282 } else {
283 if (is_reference_type(bt)) {
284 field_type = TypeOopPtr::make_from_klass(field->type()->as_klass());
285 } else {
286 field_type = Type::BOTTOM;
287 }
288 }
289 Node* adr = basic_plus_adr(obj, obj, offset);
290 const TypePtr* adr_type = C->alias_type(field)->adr_type();
291 DecoratorSet decorators = IN_HEAP;
292 decorators |= is_vol ? MO_SEQ_CST : MO_UNORDERED;
293 inc_sp(1);
294 access_store_at(obj, adr, adr_type, val, field_type, bt, decorators);
295 dec_sp(1);
296 }
297
298 if (is_field) {
299 // Remember we wrote a volatile field.
300 // For not multiple copy atomic cpu (ppc64) a barrier should be issued
301 // in constructors which have such stores. See do_exits() in parse1.cpp.
302 if (is_vol) {
303 set_wrote_volatile(true);
304 }
305 set_wrote_fields(true);
306
307 // If the field is final, the rules of Java say we are in <init> or <clinit>.
308 // If the field is @Stable, we can be in any method, but we only care about
309 // constructors at this point.
310 //
311 // Note the presence of writes to final/@Stable non-static fields, so that we
312 // can insert a memory barrier later on to keep the writes from floating
313 // out of the constructor.
314 if (field->is_final() || field->is_stable()) {
315 if (field->is_final()) {
316 set_wrote_final(true);
317 }
318 if (field->is_stable()) {
319 set_wrote_stable(true);
320 }
321 if (AllocateNode::Ideal_allocation(obj) != nullptr) {
322 // Preserve allocation ptr to create precedent edge to it in membar
323 // generated on exit from constructor.
324 set_alloc_with_final_or_stable(obj);
325 }
326 }
327 }
328 }
329
330 void Parse::set_inline_type_field(Node* obj, ciField* field, Node* val) {
331 assert(_method->is_object_constructor(), "inline type is initialized outside of constructor");
332 assert(obj->as_InlineType()->is_larval(), "must be larval");
333 assert(!_gvn.type(obj)->maybe_null(), "should never be null");
334
335 // Re-execute if buffering in below code triggers deoptimization.
336 PreserveReexecuteState preexecs(this);
337 jvms()->set_should_reexecute(true);
338 inc_sp(1);
339
340 if (!val->is_InlineType() && field->type()->is_inlinetype()) {
341 // Scalarize inline type field value
342 val = InlineTypeNode::make_from_oop(this, val, field->type()->as_inline_klass());
343 } else if (val->is_InlineType() && !field->is_flat()) {
344 // Field value needs to be allocated because it can be merged with a non-inline type.
345 val = val->as_InlineType()->buffer(this);
346 }
347
348 // Clone the inline type node and set the new field value
349 InlineTypeNode* new_vt = obj->as_InlineType()->clone_if_required(&_gvn, _map);
350 new_vt->set_field_value_by_offset(field->offset_in_bytes(), val);
351 new_vt = new_vt->adjust_scalarization_depth(this);
352
353 // If the inline type is buffered and the caller might use the buffer, update it.
354 if (new_vt->is_allocated(&gvn()) && (!_caller->has_method() || C->inlining_incrementally() || _caller->method()->is_object_constructor())) {
355 new_vt->store(this, new_vt->get_oop(), new_vt->get_oop(), new_vt->bottom_type()->inline_klass(), 0, field->offset_in_bytes());
356
357 // Preserve allocation ptr to create precedent edge to it in membar
358 // generated on exit from constructor.
359 AllocateNode* alloc = AllocateNode::Ideal_allocation(new_vt->get_oop());
360 if (alloc != nullptr) {
361 set_alloc_with_final_or_stable(new_vt->get_oop());
362 }
363 set_wrote_final(true);
364 }
365
366 replace_in_map(obj, _gvn.transform(new_vt));
367 return;
368 }
369
370 //=============================================================================
371
372 void Parse::do_newarray() {
373 bool will_link;
374 ciKlass* klass = iter().get_klass(will_link);
375
376 // Uncommon Trap when class that array contains is not loaded
377 // we need the loaded class for the rest of graph; do not
378 // initialize the container class (see Java spec)!!!
379 assert(will_link, "newarray: typeflow responsibility");
380
381 ciArrayKlass* array_klass = ciArrayKlass::make(klass);
382
383 // Check that array_klass object is loaded
384 if (!array_klass->is_loaded()) {
385 // Generate uncommon_trap for unloaded array_class
386 uncommon_trap(Deoptimization::Reason_unloaded,
387 Deoptimization::Action_reinterpret,
388 array_klass);
389 return;
390 } else if (array_klass->element_klass() != nullptr &&
391 array_klass->element_klass()->is_inlinetype() &&
392 !array_klass->element_klass()->as_inline_klass()->is_initialized()) {
393 uncommon_trap(Deoptimization::Reason_uninitialized,
394 Deoptimization::Action_reinterpret,
395 nullptr);
396 return;
397 }
398
399 kill_dead_locals();
400
401 const TypeKlassPtr* array_klass_type = TypeKlassPtr::make(array_klass, Type::trust_interfaces);
402 Node* count_val = pop();
403 Node* obj = new_array(makecon(array_klass_type), count_val, 1);
404 push(obj);
405 }
406
407
408 void Parse::do_newarray(BasicType elem_type) {
409 kill_dead_locals();
410
411 Node* count_val = pop();
412 const TypeKlassPtr* array_klass = TypeKlassPtr::make(ciTypeArrayKlass::make(elem_type));
413 Node* obj = new_array(makecon(array_klass), count_val, 1);
414 // Push resultant oop onto stack
415 push(obj);
416 }
417
418 // Expand simple expressions like new int[3][5] and new Object[2][nonConLen].
419 // Also handle the degenerate 1-dimensional case of anewarray.
420 Node* Parse::expand_multianewarray(ciArrayKlass* array_klass, Node* *lengths, int ndimensions, int nargs) {
421 Node* length = lengths[0];
422 assert(length != nullptr, "");
423 Node* array = new_array(makecon(TypeKlassPtr::make(array_klass, Type::trust_interfaces)), length, nargs);
424 if (ndimensions > 1) {
425 jint length_con = find_int_con(length, -1);
426 guarantee(length_con >= 0, "non-constant multianewarray");
427 ciArrayKlass* array_klass_1 = array_klass->as_obj_array_klass()->element_klass()->as_array_klass();
428 const TypePtr* adr_type = TypeAryPtr::OOPS;
429 const TypeOopPtr* elemtype = _gvn.type(array)->is_aryptr()->elem()->make_oopptr();
430 const intptr_t header = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
431 for (jint i = 0; i < length_con; i++) {
432 Node* elem = expand_multianewarray(array_klass_1, &lengths[1], ndimensions-1, nargs);
433 intptr_t offset = header + ((intptr_t)i << LogBytesPerHeapOop);
434 Node* eaddr = basic_plus_adr(array, offset);
435 access_store_at(array, eaddr, adr_type, elem, elemtype, T_OBJECT, IN_HEAP | IS_ARRAY);
436 }
437 }
438 return array;
439 }
440
441 void Parse::do_multianewarray() {
442 int ndimensions = iter().get_dimensions();
443
444 // the m-dimensional array
445 bool will_link;
446 ciArrayKlass* array_klass = iter().get_klass(will_link)->as_array_klass();
447 assert(will_link, "multianewarray: typeflow responsibility");
448
449 // Note: Array classes are always initialized; no is_initialized check.
450
451 kill_dead_locals();
452
453 // get the lengths from the stack (first dimension is on top)
454 Node** length = NEW_RESOURCE_ARRAY(Node*, ndimensions + 1);
455 length[ndimensions] = nullptr; // terminating null for make_runtime_call
456 int j;
457 ciKlass* elem_klass = array_klass;
458 for (j = ndimensions-1; j >= 0; j--) {
459 length[j] = pop();
460 elem_klass = elem_klass->as_array_klass()->element_klass();
461 }
462 if (elem_klass != nullptr && elem_klass->is_inlinetype() && !elem_klass->as_inline_klass()->is_initialized()) {
463 inc_sp(ndimensions);
464 uncommon_trap(Deoptimization::Reason_uninitialized,
465 Deoptimization::Action_reinterpret,
466 nullptr);
467 return;
468 }
469
470 // The original expression was of this form: new T[length0][length1]...
471 // It is often the case that the lengths are small (except the last).
472 // If that happens, use the fast 1-d creator a constant number of times.
473 const int expand_limit = MIN2((int)MultiArrayExpandLimit, 100);
474 int64_t expand_count = 1; // count of allocations in the expansion
475 int64_t expand_fanout = 1; // running total fanout
476 for (j = 0; j < ndimensions-1; j++) {
477 int dim_con = find_int_con(length[j], -1);
478 // To prevent overflow, we use 64-bit values. Alternatively,
479 // we could clamp dim_con like so:
480 // dim_con = MIN2(dim_con, expand_limit);
481 expand_fanout *= dim_con;
482 expand_count += expand_fanout; // count the level-J sub-arrays
483 if (dim_con <= 0
484 || dim_con > expand_limit
485 || expand_count > expand_limit) {
486 expand_count = 0;
487 break;
488 }
489 }
490
491 // Can use multianewarray instead of [a]newarray if only one dimension,
492 // or if all non-final dimensions are small constants.
493 if (ndimensions == 1 || (1 <= expand_count && expand_count <= expand_limit)) {
494 Node* obj = nullptr;
495 // Set the original stack and the reexecute bit for the interpreter
496 // to reexecute the multianewarray bytecode if deoptimization happens.
497 // Do it unconditionally even for one dimension multianewarray.
498 // Note: the reexecute bit will be set in GraphKit::add_safepoint_edges()
499 // when AllocateArray node for newarray is created.
500 { PreserveReexecuteState preexecs(this);
501 inc_sp(ndimensions);
502 // Pass 0 as nargs since uncommon trap code does not need to restore stack.
503 obj = expand_multianewarray(array_klass, &length[0], ndimensions, 0);
504 } //original reexecute and sp are set back here
505 push(obj);
506 return;
507 }
508
509 address fun = nullptr;
510 switch (ndimensions) {
511 case 1: ShouldNotReachHere(); break;
512 case 2: fun = OptoRuntime::multianewarray2_Java(); break;
513 case 3: fun = OptoRuntime::multianewarray3_Java(); break;
514 case 4: fun = OptoRuntime::multianewarray4_Java(); break;
515 case 5: fun = OptoRuntime::multianewarray5_Java(); break;
516 };
517 Node* c = nullptr;
518
519 if (fun != nullptr) {
520 c = make_runtime_call(RC_NO_LEAF | RC_NO_IO,
521 OptoRuntime::multianewarray_Type(ndimensions),
522 fun, nullptr, TypeRawPtr::BOTTOM,
523 makecon(TypeKlassPtr::make(array_klass, Type::trust_interfaces)),
524 length[0], length[1], length[2],
525 (ndimensions > 2) ? length[3] : nullptr,
526 (ndimensions > 3) ? length[4] : nullptr);
527 } else {
528 // Create a java array for dimension sizes
529 Node* dims = nullptr;
530 { PreserveReexecuteState preexecs(this);
531 inc_sp(ndimensions);
532 Node* dims_array_klass = makecon(TypeKlassPtr::make(ciArrayKlass::make(ciType::make(T_INT))));
533 dims = new_array(dims_array_klass, intcon(ndimensions), 0);
534
535 // Fill-in it with values
536 for (j = 0; j < ndimensions; j++) {
537 Node *dims_elem = array_element_address(dims, intcon(j), T_INT);
538 store_to_memory(control(), dims_elem, length[j], T_INT, MemNode::unordered);
539 }
540 }
541
542 c = make_runtime_call(RC_NO_LEAF | RC_NO_IO,
543 OptoRuntime::multianewarrayN_Type(),
544 OptoRuntime::multianewarrayN_Java(), nullptr, TypeRawPtr::BOTTOM,
545 makecon(TypeKlassPtr::make(array_klass, Type::trust_interfaces)),
546 dims);
547 }
548 make_slow_call_ex(c, env()->Throwable_klass(), false);
549
550 Node* res = _gvn.transform(new ProjNode(c, TypeFunc::Parms));
551
552 const Type* type = TypeOopPtr::make_from_klass_raw(array_klass, Type::trust_interfaces);
553
554 // Improve the type: We know it's not null, exact, and of a given length.
555 type = type->is_ptr()->cast_to_ptr_type(TypePtr::NotNull);
556 type = type->is_aryptr()->cast_to_exactness(true);
557
558 const TypeInt* ltype = _gvn.find_int_type(length[0]);
559 if (ltype != nullptr)
560 type = type->is_aryptr()->cast_to_size(ltype);
561
562 // We cannot sharpen the nested sub-arrays, since the top level is mutable.
563
564 Node* cast = _gvn.transform( new CheckCastPPNode(control(), res, type) );
565 push(cast);
566
567 // Possible improvements:
568 // - Make a fast path for small multi-arrays. (W/ implicit init. loops.)
569 // - Issue CastII against length[*] values, to TypeInt::POS.
570 }