Thu, 14 Apr 2011 13:45:41 -0700
Merge
1 /*
2 * Copyright (c) 1997, 2010, 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 */
25 #include "precompiled.hpp"
26 #include "interpreter/interpreter.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "oops/markOop.hpp"
29 #include "oops/methodOop.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/frame.inline.hpp"
32 #include "runtime/handles.inline.hpp"
33 #include "runtime/javaCalls.hpp"
34 #include "runtime/monitorChunk.hpp"
35 #include "runtime/signature.hpp"
36 #include "runtime/stubCodeGenerator.hpp"
37 #include "runtime/stubRoutines.hpp"
38 #include "vmreg_x86.inline.hpp"
39 #ifdef COMPILER1
40 #include "c1/c1_Runtime1.hpp"
41 #include "runtime/vframeArray.hpp"
42 #endif
44 #ifdef ASSERT
45 void RegisterMap::check_location_valid() {
46 }
47 #endif
50 // Profiling/safepoint support
52 bool frame::safe_for_sender(JavaThread *thread) {
53 address sp = (address)_sp;
54 address fp = (address)_fp;
55 address unextended_sp = (address)_unextended_sp;
56 // sp must be within the stack
57 bool sp_safe = (sp <= thread->stack_base()) &&
58 (sp >= thread->stack_base() - thread->stack_size());
60 if (!sp_safe) {
61 return false;
62 }
64 // unextended sp must be within the stack and above or equal sp
65 bool unextended_sp_safe = (unextended_sp <= thread->stack_base()) &&
66 (unextended_sp >= sp);
68 if (!unextended_sp_safe) {
69 return false;
70 }
72 // an fp must be within the stack and above (but not equal) sp
73 bool fp_safe = (fp <= thread->stack_base()) && (fp > sp);
75 // We know sp/unextended_sp are safe only fp is questionable here
77 // If the current frame is known to the code cache then we can attempt to
78 // to construct the sender and do some validation of it. This goes a long way
79 // toward eliminating issues when we get in frame construction code
81 if (_cb != NULL ) {
83 // First check if frame is complete and tester is reliable
84 // Unfortunately we can only check frame complete for runtime stubs and nmethod
85 // other generic buffer blobs are more problematic so we just assume they are
86 // ok. adapter blobs never have a frame complete and are never ok.
88 if (!_cb->is_frame_complete_at(_pc)) {
89 if (_cb->is_nmethod() || _cb->is_adapter_blob() || _cb->is_runtime_stub()) {
90 return false;
91 }
92 }
93 // Entry frame checks
94 if (is_entry_frame()) {
95 // an entry frame must have a valid fp.
97 if (!fp_safe) return false;
99 // Validate the JavaCallWrapper an entry frame must have
101 address jcw = (address)entry_frame_call_wrapper();
103 bool jcw_safe = (jcw <= thread->stack_base()) && ( jcw > fp);
105 return jcw_safe;
107 }
109 intptr_t* sender_sp = NULL;
110 address sender_pc = NULL;
112 if (is_interpreted_frame()) {
113 // fp must be safe
114 if (!fp_safe) {
115 return false;
116 }
118 sender_pc = (address) this->fp()[return_addr_offset];
119 sender_sp = (intptr_t*) addr_at(sender_sp_offset);
121 } else {
122 // must be some sort of compiled/runtime frame
123 // fp does not have to be safe (although it could be check for c1?)
125 sender_sp = _unextended_sp + _cb->frame_size();
126 // On Intel the return_address is always the word on the stack
127 sender_pc = (address) *(sender_sp-1);
128 }
130 // We must always be able to find a recognizable pc
131 CodeBlob* sender_blob = CodeCache::find_blob_unsafe(sender_pc);
132 if (sender_pc == NULL || sender_blob == NULL) {
133 return false;
134 }
137 // If the potential sender is the interpreter then we can do some more checking
138 if (Interpreter::contains(sender_pc)) {
140 // ebp is always saved in a recognizable place in any code we generate. However
141 // only if the sender is interpreted/call_stub (c1 too?) are we certain that the saved ebp
142 // is really a frame pointer.
144 intptr_t *saved_fp = (intptr_t*)*(sender_sp - frame::sender_sp_offset);
145 bool saved_fp_safe = ((address)saved_fp <= thread->stack_base()) && (saved_fp > sender_sp);
147 if (!saved_fp_safe) {
148 return false;
149 }
151 // construct the potential sender
153 frame sender(sender_sp, saved_fp, sender_pc);
155 return sender.is_interpreted_frame_valid(thread);
157 }
159 // Could just be some random pointer within the codeBlob
160 if (!sender_blob->code_contains(sender_pc)) {
161 return false;
162 }
164 // We should never be able to see an adapter if the current frame is something from code cache
165 if (sender_blob->is_adapter_blob()) {
166 return false;
167 }
169 // Could be the call_stub
171 if (StubRoutines::returns_to_call_stub(sender_pc)) {
172 intptr_t *saved_fp = (intptr_t*)*(sender_sp - frame::sender_sp_offset);
173 bool saved_fp_safe = ((address)saved_fp <= thread->stack_base()) && (saved_fp > sender_sp);
175 if (!saved_fp_safe) {
176 return false;
177 }
179 // construct the potential sender
181 frame sender(sender_sp, saved_fp, sender_pc);
183 // Validate the JavaCallWrapper an entry frame must have
184 address jcw = (address)sender.entry_frame_call_wrapper();
186 bool jcw_safe = (jcw <= thread->stack_base()) && ( jcw > (address)sender.fp());
188 return jcw_safe;
189 }
191 // If the frame size is 0 something is bad because every nmethod has a non-zero frame size
192 // because the return address counts against the callee's frame.
194 if (sender_blob->frame_size() == 0) {
195 assert(!sender_blob->is_nmethod(), "should count return address at least");
196 return false;
197 }
199 // We should never be able to see anything here except an nmethod. If something in the
200 // code cache (current frame) is called by an entity within the code cache that entity
201 // should not be anything but the call stub (already covered), the interpreter (already covered)
202 // or an nmethod.
204 assert(sender_blob->is_nmethod(), "Impossible call chain");
206 // Could put some more validation for the potential non-interpreted sender
207 // frame we'd create by calling sender if I could think of any. Wait for next crash in forte...
209 // One idea is seeing if the sender_pc we have is one that we'd expect to call to current cb
211 // We've validated the potential sender that would be created
212 return true;
213 }
215 // Must be native-compiled frame. Since sender will try and use fp to find
216 // linkages it must be safe
218 if (!fp_safe) {
219 return false;
220 }
222 // Will the pc we fetch be non-zero (which we'll find at the oldest frame)
224 if ( (address) this->fp()[return_addr_offset] == NULL) return false;
227 // could try and do some more potential verification of native frame if we could think of some...
229 return true;
231 }
234 void frame::patch_pc(Thread* thread, address pc) {
235 if (TracePcPatching) {
236 tty->print_cr("patch_pc at address" INTPTR_FORMAT " [" INTPTR_FORMAT " -> " INTPTR_FORMAT "] ",
237 &((address *)sp())[-1], ((address *)sp())[-1], pc);
238 }
239 ((address *)sp())[-1] = pc;
240 _cb = CodeCache::find_blob(pc);
241 address original_pc = nmethod::get_deopt_original_pc(this);
242 if (original_pc != NULL) {
243 assert(original_pc == _pc, "expected original PC to be stored before patching");
244 _deopt_state = is_deoptimized;
245 // leave _pc as is
246 } else {
247 _deopt_state = not_deoptimized;
248 _pc = pc;
249 }
250 }
252 bool frame::is_interpreted_frame() const {
253 return Interpreter::contains(pc());
254 }
256 int frame::frame_size(RegisterMap* map) const {
257 frame sender = this->sender(map);
258 return sender.sp() - sp();
259 }
261 intptr_t* frame::entry_frame_argument_at(int offset) const {
262 // convert offset to index to deal with tsi
263 int index = (Interpreter::expr_offset_in_bytes(offset)/wordSize);
264 // Entry frame's arguments are always in relation to unextended_sp()
265 return &unextended_sp()[index];
266 }
268 // sender_sp
269 #ifdef CC_INTERP
270 intptr_t* frame::interpreter_frame_sender_sp() const {
271 assert(is_interpreted_frame(), "interpreted frame expected");
272 // QQQ why does this specialize method exist if frame::sender_sp() does same thing?
273 // seems odd and if we always know interpreted vs. non then sender_sp() is really
274 // doing too much work.
275 return get_interpreterState()->sender_sp();
276 }
278 // monitor elements
280 BasicObjectLock* frame::interpreter_frame_monitor_begin() const {
281 return get_interpreterState()->monitor_base();
282 }
284 BasicObjectLock* frame::interpreter_frame_monitor_end() const {
285 return (BasicObjectLock*) get_interpreterState()->stack_base();
286 }
288 #else // CC_INTERP
290 intptr_t* frame::interpreter_frame_sender_sp() const {
291 assert(is_interpreted_frame(), "interpreted frame expected");
292 return (intptr_t*) at(interpreter_frame_sender_sp_offset);
293 }
295 void frame::set_interpreter_frame_sender_sp(intptr_t* sender_sp) {
296 assert(is_interpreted_frame(), "interpreted frame expected");
297 ptr_at_put(interpreter_frame_sender_sp_offset, (intptr_t) sender_sp);
298 }
301 // monitor elements
303 BasicObjectLock* frame::interpreter_frame_monitor_begin() const {
304 return (BasicObjectLock*) addr_at(interpreter_frame_monitor_block_bottom_offset);
305 }
307 BasicObjectLock* frame::interpreter_frame_monitor_end() const {
308 BasicObjectLock* result = (BasicObjectLock*) *addr_at(interpreter_frame_monitor_block_top_offset);
309 // make sure the pointer points inside the frame
310 assert(sp() <= (intptr_t*) result, "monitor end should be above the stack pointer");
311 assert((intptr_t*) result < fp(), "monitor end should be strictly below the frame pointer");
312 return result;
313 }
315 void frame::interpreter_frame_set_monitor_end(BasicObjectLock* value) {
316 *((BasicObjectLock**)addr_at(interpreter_frame_monitor_block_top_offset)) = value;
317 }
319 // Used by template based interpreter deoptimization
320 void frame::interpreter_frame_set_last_sp(intptr_t* sp) {
321 *((intptr_t**)addr_at(interpreter_frame_last_sp_offset)) = sp;
322 }
323 #endif // CC_INTERP
325 frame frame::sender_for_entry_frame(RegisterMap* map) const {
326 assert(map != NULL, "map must be set");
327 // Java frame called from C; skip all C frames and return top C
328 // frame of that chunk as the sender
329 JavaFrameAnchor* jfa = entry_frame_call_wrapper()->anchor();
330 assert(!entry_frame_is_first(), "next Java fp must be non zero");
331 assert(jfa->last_Java_sp() > sp(), "must be above this frame on stack");
332 map->clear();
333 assert(map->include_argument_oops(), "should be set by clear");
334 if (jfa->last_Java_pc() != NULL ) {
335 frame fr(jfa->last_Java_sp(), jfa->last_Java_fp(), jfa->last_Java_pc());
336 return fr;
337 }
338 frame fr(jfa->last_Java_sp(), jfa->last_Java_fp());
339 return fr;
340 }
343 //------------------------------------------------------------------------------
344 // frame::verify_deopt_original_pc
345 //
346 // Verifies the calculated original PC of a deoptimization PC for the
347 // given unextended SP. The unextended SP might also be the saved SP
348 // for MethodHandle call sites.
349 #if ASSERT
350 void frame::verify_deopt_original_pc(nmethod* nm, intptr_t* unextended_sp, bool is_method_handle_return) {
351 frame fr;
353 // This is ugly but it's better than to change {get,set}_original_pc
354 // to take an SP value as argument. And it's only a debugging
355 // method anyway.
356 fr._unextended_sp = unextended_sp;
358 address original_pc = nm->get_original_pc(&fr);
359 assert(nm->insts_contains(original_pc), "original PC must be in nmethod");
360 assert(nm->is_method_handle_return(original_pc) == is_method_handle_return, "must be");
361 }
362 #endif
365 //------------------------------------------------------------------------------
366 // frame::sender_for_interpreter_frame
367 frame frame::sender_for_interpreter_frame(RegisterMap* map) const {
368 // SP is the raw SP from the sender after adapter or interpreter
369 // extension.
370 intptr_t* sender_sp = this->sender_sp();
372 // This is the sp before any possible extension (adapter/locals).
373 intptr_t* unextended_sp = interpreter_frame_sender_sp();
375 // Stored FP.
376 intptr_t* saved_fp = link();
378 address sender_pc = this->sender_pc();
379 CodeBlob* sender_cb = CodeCache::find_blob_unsafe(sender_pc);
380 assert(sender_cb, "sanity");
381 nmethod* sender_nm = sender_cb->as_nmethod_or_null();
383 if (sender_nm != NULL) {
384 // If the sender PC is a deoptimization point, get the original
385 // PC. For MethodHandle call site the unextended_sp is stored in
386 // saved_fp.
387 if (sender_nm->is_deopt_mh_entry(sender_pc)) {
388 DEBUG_ONLY(verify_deopt_mh_original_pc(sender_nm, saved_fp));
389 unextended_sp = saved_fp;
390 }
391 else if (sender_nm->is_deopt_entry(sender_pc)) {
392 DEBUG_ONLY(verify_deopt_original_pc(sender_nm, unextended_sp));
393 }
394 else if (sender_nm->is_method_handle_return(sender_pc)) {
395 unextended_sp = saved_fp;
396 }
397 }
399 // The interpreter and compiler(s) always save EBP/RBP in a known
400 // location on entry. We must record where that location is
401 // so this if EBP/RBP was live on callout from c2 we can find
402 // the saved copy no matter what it called.
404 // Since the interpreter always saves EBP/RBP if we record where it is then
405 // we don't have to always save EBP/RBP on entry and exit to c2 compiled
406 // code, on entry will be enough.
407 #ifdef COMPILER2
408 if (map->update_map()) {
409 map->set_location(rbp->as_VMReg(), (address) addr_at(link_offset));
410 #ifdef AMD64
411 // this is weird "H" ought to be at a higher address however the
412 // oopMaps seems to have the "H" regs at the same address and the
413 // vanilla register.
414 // XXXX make this go away
415 if (true) {
416 map->set_location(rbp->as_VMReg()->next(), (address)addr_at(link_offset));
417 }
418 #endif // AMD64
419 }
420 #endif // COMPILER2
422 return frame(sender_sp, unextended_sp, saved_fp, sender_pc);
423 }
426 //------------------------------------------------------------------------------
427 // frame::sender_for_compiled_frame
428 frame frame::sender_for_compiled_frame(RegisterMap* map) const {
429 assert(map != NULL, "map must be set");
431 // frame owned by optimizing compiler
432 assert(_cb->frame_size() >= 0, "must have non-zero frame size");
433 intptr_t* sender_sp = unextended_sp() + _cb->frame_size();
434 intptr_t* unextended_sp = sender_sp;
436 // On Intel the return_address is always the word on the stack
437 address sender_pc = (address) *(sender_sp-1);
439 // This is the saved value of EBP which may or may not really be an FP.
440 // It is only an FP if the sender is an interpreter frame (or C1?).
441 intptr_t* saved_fp = (intptr_t*) *(sender_sp - frame::sender_sp_offset);
443 // If we are returning to a compiled MethodHandle call site, the
444 // saved_fp will in fact be a saved value of the unextended SP. The
445 // simplest way to tell whether we are returning to such a call site
446 // is as follows:
447 CodeBlob* sender_cb = CodeCache::find_blob_unsafe(sender_pc);
448 assert(sender_cb, "sanity");
449 nmethod* sender_nm = sender_cb->as_nmethod_or_null();
451 if (sender_nm != NULL) {
452 // If the sender PC is a deoptimization point, get the original
453 // PC. For MethodHandle call site the unextended_sp is stored in
454 // saved_fp.
455 if (sender_nm->is_deopt_mh_entry(sender_pc)) {
456 DEBUG_ONLY(verify_deopt_mh_original_pc(sender_nm, saved_fp));
457 unextended_sp = saved_fp;
458 }
459 else if (sender_nm->is_deopt_entry(sender_pc)) {
460 DEBUG_ONLY(verify_deopt_original_pc(sender_nm, unextended_sp));
461 }
462 else if (sender_nm->is_method_handle_return(sender_pc)) {
463 unextended_sp = saved_fp;
464 }
465 }
467 if (map->update_map()) {
468 // Tell GC to use argument oopmaps for some runtime stubs that need it.
469 // For C1, the runtime stub might not have oop maps, so set this flag
470 // outside of update_register_map.
471 map->set_include_argument_oops(_cb->caller_must_gc_arguments(map->thread()));
472 if (_cb->oop_maps() != NULL) {
473 OopMapSet::update_register_map(this, map);
474 }
475 // Since the prolog does the save and restore of EBP there is no oopmap
476 // for it so we must fill in its location as if there was an oopmap entry
477 // since if our caller was compiled code there could be live jvm state in it.
478 map->set_location(rbp->as_VMReg(), (address) (sender_sp - frame::sender_sp_offset));
479 #ifdef AMD64
480 // this is weird "H" ought to be at a higher address however the
481 // oopMaps seems to have the "H" regs at the same address and the
482 // vanilla register.
483 // XXXX make this go away
484 if (true) {
485 map->set_location(rbp->as_VMReg()->next(), (address) (sender_sp - frame::sender_sp_offset));
486 }
487 #endif // AMD64
488 }
490 assert(sender_sp != sp(), "must have changed");
491 return frame(sender_sp, unextended_sp, saved_fp, sender_pc);
492 }
495 //------------------------------------------------------------------------------
496 // frame::sender
497 frame frame::sender(RegisterMap* map) const {
498 // Default is we done have to follow them. The sender_for_xxx will
499 // update it accordingly
500 map->set_include_argument_oops(false);
502 if (is_entry_frame()) return sender_for_entry_frame(map);
503 if (is_interpreted_frame()) return sender_for_interpreter_frame(map);
504 assert(_cb == CodeCache::find_blob(pc()),"Must be the same");
506 if (_cb != NULL) {
507 return sender_for_compiled_frame(map);
508 }
509 // Must be native-compiled frame, i.e. the marshaling code for native
510 // methods that exists in the core system.
511 return frame(sender_sp(), link(), sender_pc());
512 }
515 bool frame::interpreter_frame_equals_unpacked_fp(intptr_t* fp) {
516 assert(is_interpreted_frame(), "must be interpreter frame");
517 methodOop method = interpreter_frame_method();
518 // When unpacking an optimized frame the frame pointer is
519 // adjusted with:
520 int diff = (method->max_locals() - method->size_of_parameters()) *
521 Interpreter::stackElementWords;
522 return _fp == (fp - diff);
523 }
525 void frame::pd_gc_epilog() {
526 // nothing done here now
527 }
529 bool frame::is_interpreted_frame_valid(JavaThread* thread) const {
530 // QQQ
531 #ifdef CC_INTERP
532 #else
533 assert(is_interpreted_frame(), "Not an interpreted frame");
534 // These are reasonable sanity checks
535 if (fp() == 0 || (intptr_t(fp()) & (wordSize-1)) != 0) {
536 return false;
537 }
538 if (sp() == 0 || (intptr_t(sp()) & (wordSize-1)) != 0) {
539 return false;
540 }
541 if (fp() + interpreter_frame_initial_sp_offset < sp()) {
542 return false;
543 }
544 // These are hacks to keep us out of trouble.
545 // The problem with these is that they mask other problems
546 if (fp() <= sp()) { // this attempts to deal with unsigned comparison above
547 return false;
548 }
550 // do some validation of frame elements
552 // first the method
554 methodOop m = *interpreter_frame_method_addr();
556 // validate the method we'd find in this potential sender
557 if (!Universe::heap()->is_valid_method(m)) return false;
559 // stack frames shouldn't be much larger than max_stack elements
561 if (fp() - sp() > 1024 + m->max_stack()*Interpreter::stackElementSize) {
562 return false;
563 }
565 // validate bci/bcx
567 intptr_t bcx = interpreter_frame_bcx();
568 if (m->validate_bci_from_bcx(bcx) < 0) {
569 return false;
570 }
572 // validate constantPoolCacheOop
574 constantPoolCacheOop cp = *interpreter_frame_cache_addr();
576 if (cp == NULL ||
577 !Space::is_aligned(cp) ||
578 !Universe::heap()->is_permanent((void*)cp)) return false;
580 // validate locals
582 address locals = (address) *interpreter_frame_locals_addr();
584 if (locals > thread->stack_base() || locals < (address) fp()) return false;
586 // We'd have to be pretty unlucky to be mislead at this point
588 #endif // CC_INTERP
589 return true;
590 }
592 BasicType frame::interpreter_frame_result(oop* oop_result, jvalue* value_result) {
593 #ifdef CC_INTERP
594 // Needed for JVMTI. The result should always be in the
595 // interpreterState object
596 interpreterState istate = get_interpreterState();
597 #endif // CC_INTERP
598 assert(is_interpreted_frame(), "interpreted frame expected");
599 methodOop method = interpreter_frame_method();
600 BasicType type = method->result_type();
602 intptr_t* tos_addr;
603 if (method->is_native()) {
604 // Prior to calling into the runtime to report the method_exit the possible
605 // return value is pushed to the native stack. If the result is a jfloat/jdouble
606 // then ST0 is saved before EAX/EDX. See the note in generate_native_result
607 tos_addr = (intptr_t*)sp();
608 if (type == T_FLOAT || type == T_DOUBLE) {
609 // QQQ seems like this code is equivalent on the two platforms
610 #ifdef AMD64
611 // This is times two because we do a push(ltos) after pushing XMM0
612 // and that takes two interpreter stack slots.
613 tos_addr += 2 * Interpreter::stackElementWords;
614 #else
615 tos_addr += 2;
616 #endif // AMD64
617 }
618 } else {
619 tos_addr = (intptr_t*)interpreter_frame_tos_address();
620 }
622 switch (type) {
623 case T_OBJECT :
624 case T_ARRAY : {
625 oop obj;
626 if (method->is_native()) {
627 #ifdef CC_INTERP
628 obj = istate->_oop_temp;
629 #else
630 obj = (oop) at(interpreter_frame_oop_temp_offset);
631 #endif // CC_INTERP
632 } else {
633 oop* obj_p = (oop*)tos_addr;
634 obj = (obj_p == NULL) ? (oop)NULL : *obj_p;
635 }
636 assert(obj == NULL || Universe::heap()->is_in(obj), "sanity check");
637 *oop_result = obj;
638 break;
639 }
640 case T_BOOLEAN : value_result->z = *(jboolean*)tos_addr; break;
641 case T_BYTE : value_result->b = *(jbyte*)tos_addr; break;
642 case T_CHAR : value_result->c = *(jchar*)tos_addr; break;
643 case T_SHORT : value_result->s = *(jshort*)tos_addr; break;
644 case T_INT : value_result->i = *(jint*)tos_addr; break;
645 case T_LONG : value_result->j = *(jlong*)tos_addr; break;
646 case T_FLOAT : {
647 #ifdef AMD64
648 value_result->f = *(jfloat*)tos_addr;
649 #else
650 if (method->is_native()) {
651 jdouble d = *(jdouble*)tos_addr; // Result was in ST0 so need to convert to jfloat
652 value_result->f = (jfloat)d;
653 } else {
654 value_result->f = *(jfloat*)tos_addr;
655 }
656 #endif // AMD64
657 break;
658 }
659 case T_DOUBLE : value_result->d = *(jdouble*)tos_addr; break;
660 case T_VOID : /* Nothing to do */ break;
661 default : ShouldNotReachHere();
662 }
664 return type;
665 }
668 intptr_t* frame::interpreter_frame_tos_at(jint offset) const {
669 int index = (Interpreter::expr_offset_in_bytes(offset)/wordSize);
670 return &interpreter_frame_tos_address()[index];
671 }