Thu, 21 Mar 2013 09:27:54 +0100
7153771: array bound check elimination for c1
Summary: when possible optimize out array bound checks, inserting predicates when needed.
Reviewed-by: never, kvn, twisti
Contributed-by: thomaswue <thomas.wuerthinger@oracle.com>
1 /*
2 * Copyright (c) 1997, 2012, 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.
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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 *
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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.
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23 */
25 #include "precompiled.hpp"
26 #include "interpreter/interpreter.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "oops/markOop.hpp"
29 #include "oops/method.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "prims/methodHandles.hpp"
32 #include "runtime/frame.inline.hpp"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/javaCalls.hpp"
35 #include "runtime/monitorChunk.hpp"
36 #include "runtime/signature.hpp"
37 #include "runtime/stubCodeGenerator.hpp"
38 #include "runtime/stubRoutines.hpp"
39 #include "vmreg_x86.inline.hpp"
40 #ifdef COMPILER1
41 #include "c1/c1_Runtime1.hpp"
42 #include "runtime/vframeArray.hpp"
43 #endif
45 #ifdef ASSERT
46 void RegisterMap::check_location_valid() {
47 }
48 #endif
51 // Profiling/safepoint support
53 bool frame::safe_for_sender(JavaThread *thread) {
54 address sp = (address)_sp;
55 address fp = (address)_fp;
56 address unextended_sp = (address)_unextended_sp;
57 // sp must be within the stack
58 bool sp_safe = (sp <= thread->stack_base()) &&
59 (sp >= thread->stack_base() - thread->stack_size());
61 if (!sp_safe) {
62 return false;
63 }
65 // unextended sp must be within the stack and above or equal sp
66 bool unextended_sp_safe = (unextended_sp <= thread->stack_base()) &&
67 (unextended_sp >= sp);
69 if (!unextended_sp_safe) {
70 return false;
71 }
73 // an fp must be within the stack and above (but not equal) sp
74 bool fp_safe = (fp <= thread->stack_base()) && (fp > sp);
76 // We know sp/unextended_sp are safe only fp is questionable here
78 // If the current frame is known to the code cache then we can attempt to
79 // to construct the sender and do some validation of it. This goes a long way
80 // toward eliminating issues when we get in frame construction code
82 if (_cb != NULL ) {
84 // First check if frame is complete and tester is reliable
85 // Unfortunately we can only check frame complete for runtime stubs and nmethod
86 // other generic buffer blobs are more problematic so we just assume they are
87 // ok. adapter blobs never have a frame complete and are never ok.
89 if (!_cb->is_frame_complete_at(_pc)) {
90 if (_cb->is_nmethod() || _cb->is_adapter_blob() || _cb->is_runtime_stub()) {
91 return false;
92 }
93 }
95 // Could just be some random pointer within the codeBlob
96 if (!_cb->code_contains(_pc)) {
97 return false;
98 }
100 // Entry frame checks
101 if (is_entry_frame()) {
102 // an entry frame must have a valid fp.
104 if (!fp_safe) return false;
106 // Validate the JavaCallWrapper an entry frame must have
108 address jcw = (address)entry_frame_call_wrapper();
110 bool jcw_safe = (jcw <= thread->stack_base()) && ( jcw > fp);
112 return jcw_safe;
114 }
116 intptr_t* sender_sp = NULL;
117 address sender_pc = NULL;
119 if (is_interpreted_frame()) {
120 // fp must be safe
121 if (!fp_safe) {
122 return false;
123 }
125 sender_pc = (address) this->fp()[return_addr_offset];
126 sender_sp = (intptr_t*) addr_at(sender_sp_offset);
128 } else {
129 // must be some sort of compiled/runtime frame
130 // fp does not have to be safe (although it could be check for c1?)
132 sender_sp = _unextended_sp + _cb->frame_size();
133 // On Intel the return_address is always the word on the stack
134 sender_pc = (address) *(sender_sp-1);
135 }
137 // We must always be able to find a recognizable pc
138 CodeBlob* sender_blob = CodeCache::find_blob_unsafe(sender_pc);
139 if (sender_pc == NULL || sender_blob == NULL) {
140 return false;
141 }
144 // If the potential sender is the interpreter then we can do some more checking
145 if (Interpreter::contains(sender_pc)) {
147 // ebp is always saved in a recognizable place in any code we generate. However
148 // only if the sender is interpreted/call_stub (c1 too?) are we certain that the saved ebp
149 // is really a frame pointer.
151 intptr_t *saved_fp = (intptr_t*)*(sender_sp - frame::sender_sp_offset);
152 bool saved_fp_safe = ((address)saved_fp <= thread->stack_base()) && (saved_fp > sender_sp);
154 if (!saved_fp_safe) {
155 return false;
156 }
158 // construct the potential sender
160 frame sender(sender_sp, saved_fp, sender_pc);
162 return sender.is_interpreted_frame_valid(thread);
164 }
166 // Could just be some random pointer within the codeBlob
167 if (!sender_blob->code_contains(sender_pc)) {
168 return false;
169 }
171 // We should never be able to see an adapter if the current frame is something from code cache
172 if (sender_blob->is_adapter_blob()) {
173 return false;
174 }
176 // Could be the call_stub
178 if (StubRoutines::returns_to_call_stub(sender_pc)) {
179 intptr_t *saved_fp = (intptr_t*)*(sender_sp - frame::sender_sp_offset);
180 bool saved_fp_safe = ((address)saved_fp <= thread->stack_base()) && (saved_fp > sender_sp);
182 if (!saved_fp_safe) {
183 return false;
184 }
186 // construct the potential sender
188 frame sender(sender_sp, saved_fp, sender_pc);
190 // Validate the JavaCallWrapper an entry frame must have
191 address jcw = (address)sender.entry_frame_call_wrapper();
193 bool jcw_safe = (jcw <= thread->stack_base()) && ( jcw > (address)sender.fp());
195 return jcw_safe;
196 }
198 // If the frame size is 0 something is bad because every nmethod has a non-zero frame size
199 // because the return address counts against the callee's frame.
201 if (sender_blob->frame_size() == 0) {
202 assert(!sender_blob->is_nmethod(), "should count return address at least");
203 return false;
204 }
206 // We should never be able to see anything here except an nmethod. If something in the
207 // code cache (current frame) is called by an entity within the code cache that entity
208 // should not be anything but the call stub (already covered), the interpreter (already covered)
209 // or an nmethod.
211 assert(sender_blob->is_nmethod(), "Impossible call chain");
213 // Could put some more validation for the potential non-interpreted sender
214 // frame we'd create by calling sender if I could think of any. Wait for next crash in forte...
216 // One idea is seeing if the sender_pc we have is one that we'd expect to call to current cb
218 // We've validated the potential sender that would be created
219 return true;
220 }
222 // Must be native-compiled frame. Since sender will try and use fp to find
223 // linkages it must be safe
225 if (!fp_safe) {
226 return false;
227 }
229 // Will the pc we fetch be non-zero (which we'll find at the oldest frame)
231 if ( (address) this->fp()[return_addr_offset] == NULL) return false;
234 // could try and do some more potential verification of native frame if we could think of some...
236 return true;
238 }
241 void frame::patch_pc(Thread* thread, address pc) {
242 address* pc_addr = &(((address*) sp())[-1]);
243 if (TracePcPatching) {
244 tty->print_cr("patch_pc at address " INTPTR_FORMAT " [" INTPTR_FORMAT " -> " INTPTR_FORMAT "]",
245 pc_addr, *pc_addr, pc);
246 }
247 // Either the return address is the original one or we are going to
248 // patch in the same address that's already there.
249 assert(_pc == *pc_addr || pc == *pc_addr, "must be");
250 *pc_addr = pc;
251 _cb = CodeCache::find_blob(pc);
252 address original_pc = nmethod::get_deopt_original_pc(this);
253 if (original_pc != NULL) {
254 assert(original_pc == _pc, "expected original PC to be stored before patching");
255 _deopt_state = is_deoptimized;
256 // leave _pc as is
257 } else {
258 _deopt_state = not_deoptimized;
259 _pc = pc;
260 }
261 }
263 bool frame::is_interpreted_frame() const {
264 return Interpreter::contains(pc());
265 }
267 int frame::frame_size(RegisterMap* map) const {
268 frame sender = this->sender(map);
269 return sender.sp() - sp();
270 }
272 intptr_t* frame::entry_frame_argument_at(int offset) const {
273 // convert offset to index to deal with tsi
274 int index = (Interpreter::expr_offset_in_bytes(offset)/wordSize);
275 // Entry frame's arguments are always in relation to unextended_sp()
276 return &unextended_sp()[index];
277 }
279 // sender_sp
280 #ifdef CC_INTERP
281 intptr_t* frame::interpreter_frame_sender_sp() const {
282 assert(is_interpreted_frame(), "interpreted frame expected");
283 // QQQ why does this specialize method exist if frame::sender_sp() does same thing?
284 // seems odd and if we always know interpreted vs. non then sender_sp() is really
285 // doing too much work.
286 return get_interpreterState()->sender_sp();
287 }
289 // monitor elements
291 BasicObjectLock* frame::interpreter_frame_monitor_begin() const {
292 return get_interpreterState()->monitor_base();
293 }
295 BasicObjectLock* frame::interpreter_frame_monitor_end() const {
296 return (BasicObjectLock*) get_interpreterState()->stack_base();
297 }
299 #else // CC_INTERP
301 intptr_t* frame::interpreter_frame_sender_sp() const {
302 assert(is_interpreted_frame(), "interpreted frame expected");
303 return (intptr_t*) at(interpreter_frame_sender_sp_offset);
304 }
306 void frame::set_interpreter_frame_sender_sp(intptr_t* sender_sp) {
307 assert(is_interpreted_frame(), "interpreted frame expected");
308 ptr_at_put(interpreter_frame_sender_sp_offset, (intptr_t) sender_sp);
309 }
312 // monitor elements
314 BasicObjectLock* frame::interpreter_frame_monitor_begin() const {
315 return (BasicObjectLock*) addr_at(interpreter_frame_monitor_block_bottom_offset);
316 }
318 BasicObjectLock* frame::interpreter_frame_monitor_end() const {
319 BasicObjectLock* result = (BasicObjectLock*) *addr_at(interpreter_frame_monitor_block_top_offset);
320 // make sure the pointer points inside the frame
321 assert(sp() <= (intptr_t*) result, "monitor end should be above the stack pointer");
322 assert((intptr_t*) result < fp(), "monitor end should be strictly below the frame pointer");
323 return result;
324 }
326 void frame::interpreter_frame_set_monitor_end(BasicObjectLock* value) {
327 *((BasicObjectLock**)addr_at(interpreter_frame_monitor_block_top_offset)) = value;
328 }
330 // Used by template based interpreter deoptimization
331 void frame::interpreter_frame_set_last_sp(intptr_t* sp) {
332 *((intptr_t**)addr_at(interpreter_frame_last_sp_offset)) = sp;
333 }
334 #endif // CC_INTERP
336 frame frame::sender_for_entry_frame(RegisterMap* map) const {
337 assert(map != NULL, "map must be set");
338 // Java frame called from C; skip all C frames and return top C
339 // frame of that chunk as the sender
340 JavaFrameAnchor* jfa = entry_frame_call_wrapper()->anchor();
341 assert(!entry_frame_is_first(), "next Java fp must be non zero");
342 assert(jfa->last_Java_sp() > sp(), "must be above this frame on stack");
343 map->clear();
344 assert(map->include_argument_oops(), "should be set by clear");
345 if (jfa->last_Java_pc() != NULL ) {
346 frame fr(jfa->last_Java_sp(), jfa->last_Java_fp(), jfa->last_Java_pc());
347 return fr;
348 }
349 frame fr(jfa->last_Java_sp(), jfa->last_Java_fp());
350 return fr;
351 }
353 //------------------------------------------------------------------------------
354 // frame::verify_deopt_original_pc
355 //
356 // Verifies the calculated original PC of a deoptimization PC for the
357 // given unextended SP. The unextended SP might also be the saved SP
358 // for MethodHandle call sites.
359 #ifdef ASSERT
360 void frame::verify_deopt_original_pc(nmethod* nm, intptr_t* unextended_sp, bool is_method_handle_return) {
361 frame fr;
363 // This is ugly but it's better than to change {get,set}_original_pc
364 // to take an SP value as argument. And it's only a debugging
365 // method anyway.
366 fr._unextended_sp = unextended_sp;
368 address original_pc = nm->get_original_pc(&fr);
369 assert(nm->insts_contains(original_pc), "original PC must be in nmethod");
370 assert(nm->is_method_handle_return(original_pc) == is_method_handle_return, "must be");
371 }
372 #endif
374 //------------------------------------------------------------------------------
375 // frame::adjust_unextended_sp
376 void frame::adjust_unextended_sp() {
377 // If we are returning to a compiled MethodHandle call site, the
378 // saved_fp will in fact be a saved value of the unextended SP. The
379 // simplest way to tell whether we are returning to such a call site
380 // is as follows:
382 nmethod* sender_nm = (_cb == NULL) ? NULL : _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(_pc)) {
388 DEBUG_ONLY(verify_deopt_mh_original_pc(sender_nm, _fp));
389 _unextended_sp = _fp;
390 }
391 else if (sender_nm->is_deopt_entry(_pc)) {
392 DEBUG_ONLY(verify_deopt_original_pc(sender_nm, _unextended_sp));
393 }
394 else if (sender_nm->is_method_handle_return(_pc)) {
395 _unextended_sp = _fp;
396 }
397 }
398 }
400 //------------------------------------------------------------------------------
401 // frame::update_map_with_saved_link
402 void frame::update_map_with_saved_link(RegisterMap* map, intptr_t** link_addr) {
403 // The interpreter and compiler(s) always save EBP/RBP in a known
404 // location on entry. We must record where that location is
405 // so this if EBP/RBP was live on callout from c2 we can find
406 // the saved copy no matter what it called.
408 // Since the interpreter always saves EBP/RBP if we record where it is then
409 // we don't have to always save EBP/RBP on entry and exit to c2 compiled
410 // code, on entry will be enough.
411 map->set_location(rbp->as_VMReg(), (address) link_addr);
412 #ifdef AMD64
413 // this is weird "H" ought to be at a higher address however the
414 // oopMaps seems to have the "H" regs at the same address and the
415 // vanilla register.
416 // XXXX make this go away
417 if (true) {
418 map->set_location(rbp->as_VMReg()->next(), (address) link_addr);
419 }
420 #endif // AMD64
421 }
424 //------------------------------------------------------------------------------
425 // frame::sender_for_interpreter_frame
426 frame frame::sender_for_interpreter_frame(RegisterMap* map) const {
427 // SP is the raw SP from the sender after adapter or interpreter
428 // extension.
429 intptr_t* sender_sp = this->sender_sp();
431 // This is the sp before any possible extension (adapter/locals).
432 intptr_t* unextended_sp = interpreter_frame_sender_sp();
434 #ifdef COMPILER2
435 if (map->update_map()) {
436 update_map_with_saved_link(map, (intptr_t**) addr_at(link_offset));
437 }
438 #endif // COMPILER2
440 return frame(sender_sp, unextended_sp, link(), sender_pc());
441 }
444 //------------------------------------------------------------------------------
445 // frame::sender_for_compiled_frame
446 frame frame::sender_for_compiled_frame(RegisterMap* map) const {
447 assert(map != NULL, "map must be set");
449 // frame owned by optimizing compiler
450 assert(_cb->frame_size() >= 0, "must have non-zero frame size");
451 intptr_t* sender_sp = unextended_sp() + _cb->frame_size();
452 intptr_t* unextended_sp = sender_sp;
454 // On Intel the return_address is always the word on the stack
455 address sender_pc = (address) *(sender_sp-1);
457 // This is the saved value of EBP which may or may not really be an FP.
458 // It is only an FP if the sender is an interpreter frame (or C1?).
459 intptr_t** saved_fp_addr = (intptr_t**) (sender_sp - frame::sender_sp_offset);
461 if (map->update_map()) {
462 // Tell GC to use argument oopmaps for some runtime stubs that need it.
463 // For C1, the runtime stub might not have oop maps, so set this flag
464 // outside of update_register_map.
465 map->set_include_argument_oops(_cb->caller_must_gc_arguments(map->thread()));
466 if (_cb->oop_maps() != NULL) {
467 OopMapSet::update_register_map(this, map);
468 }
470 // Since the prolog does the save and restore of EBP there is no oopmap
471 // for it so we must fill in its location as if there was an oopmap entry
472 // since if our caller was compiled code there could be live jvm state in it.
473 update_map_with_saved_link(map, saved_fp_addr);
474 }
476 assert(sender_sp != sp(), "must have changed");
477 return frame(sender_sp, unextended_sp, *saved_fp_addr, sender_pc);
478 }
481 //------------------------------------------------------------------------------
482 // frame::sender
483 frame frame::sender(RegisterMap* map) const {
484 // Default is we done have to follow them. The sender_for_xxx will
485 // update it accordingly
486 map->set_include_argument_oops(false);
488 if (is_entry_frame()) return sender_for_entry_frame(map);
489 if (is_interpreted_frame()) return sender_for_interpreter_frame(map);
490 assert(_cb == CodeCache::find_blob(pc()),"Must be the same");
492 if (_cb != NULL) {
493 return sender_for_compiled_frame(map);
494 }
495 // Must be native-compiled frame, i.e. the marshaling code for native
496 // methods that exists in the core system.
497 return frame(sender_sp(), link(), sender_pc());
498 }
501 bool frame::interpreter_frame_equals_unpacked_fp(intptr_t* fp) {
502 assert(is_interpreted_frame(), "must be interpreter frame");
503 Method* method = interpreter_frame_method();
504 // When unpacking an optimized frame the frame pointer is
505 // adjusted with:
506 int diff = (method->max_locals() - method->size_of_parameters()) *
507 Interpreter::stackElementWords;
508 return _fp == (fp - diff);
509 }
511 void frame::pd_gc_epilog() {
512 // nothing done here now
513 }
515 bool frame::is_interpreted_frame_valid(JavaThread* thread) const {
516 // QQQ
517 #ifdef CC_INTERP
518 #else
519 assert(is_interpreted_frame(), "Not an interpreted frame");
520 // These are reasonable sanity checks
521 if (fp() == 0 || (intptr_t(fp()) & (wordSize-1)) != 0) {
522 return false;
523 }
524 if (sp() == 0 || (intptr_t(sp()) & (wordSize-1)) != 0) {
525 return false;
526 }
527 if (fp() + interpreter_frame_initial_sp_offset < sp()) {
528 return false;
529 }
530 // These are hacks to keep us out of trouble.
531 // The problem with these is that they mask other problems
532 if (fp() <= sp()) { // this attempts to deal with unsigned comparison above
533 return false;
534 }
536 // do some validation of frame elements
538 // first the method
540 Method* m = *interpreter_frame_method_addr();
542 // validate the method we'd find in this potential sender
543 if (!m->is_valid_method()) return false;
545 // stack frames shouldn't be much larger than max_stack elements
547 if (fp() - sp() > 1024 + m->max_stack()*Interpreter::stackElementSize) {
548 return false;
549 }
551 // validate bci/bcx
553 intptr_t bcx = interpreter_frame_bcx();
554 if (m->validate_bci_from_bcx(bcx) < 0) {
555 return false;
556 }
558 // validate ConstantPoolCache*
559 ConstantPoolCache* cp = *interpreter_frame_cache_addr();
560 if (cp == NULL || !cp->is_metadata()) return false;
562 // validate locals
564 address locals = (address) *interpreter_frame_locals_addr();
566 if (locals > thread->stack_base() || locals < (address) fp()) return false;
568 // We'd have to be pretty unlucky to be mislead at this point
570 #endif // CC_INTERP
571 return true;
572 }
574 BasicType frame::interpreter_frame_result(oop* oop_result, jvalue* value_result) {
575 #ifdef CC_INTERP
576 // Needed for JVMTI. The result should always be in the
577 // interpreterState object
578 interpreterState istate = get_interpreterState();
579 #endif // CC_INTERP
580 assert(is_interpreted_frame(), "interpreted frame expected");
581 Method* method = interpreter_frame_method();
582 BasicType type = method->result_type();
584 intptr_t* tos_addr;
585 if (method->is_native()) {
586 // Prior to calling into the runtime to report the method_exit the possible
587 // return value is pushed to the native stack. If the result is a jfloat/jdouble
588 // then ST0 is saved before EAX/EDX. See the note in generate_native_result
589 tos_addr = (intptr_t*)sp();
590 if (type == T_FLOAT || type == T_DOUBLE) {
591 // QQQ seems like this code is equivalent on the two platforms
592 #ifdef AMD64
593 // This is times two because we do a push(ltos) after pushing XMM0
594 // and that takes two interpreter stack slots.
595 tos_addr += 2 * Interpreter::stackElementWords;
596 #else
597 tos_addr += 2;
598 #endif // AMD64
599 }
600 } else {
601 tos_addr = (intptr_t*)interpreter_frame_tos_address();
602 }
604 switch (type) {
605 case T_OBJECT :
606 case T_ARRAY : {
607 oop obj;
608 if (method->is_native()) {
609 #ifdef CC_INTERP
610 obj = istate->_oop_temp;
611 #else
612 obj = (oop) at(interpreter_frame_oop_temp_offset);
613 #endif // CC_INTERP
614 } else {
615 oop* obj_p = (oop*)tos_addr;
616 obj = (obj_p == NULL) ? (oop)NULL : *obj_p;
617 }
618 assert(obj == NULL || Universe::heap()->is_in(obj), "sanity check");
619 *oop_result = obj;
620 break;
621 }
622 case T_BOOLEAN : value_result->z = *(jboolean*)tos_addr; break;
623 case T_BYTE : value_result->b = *(jbyte*)tos_addr; break;
624 case T_CHAR : value_result->c = *(jchar*)tos_addr; break;
625 case T_SHORT : value_result->s = *(jshort*)tos_addr; break;
626 case T_INT : value_result->i = *(jint*)tos_addr; break;
627 case T_LONG : value_result->j = *(jlong*)tos_addr; break;
628 case T_FLOAT : {
629 #ifdef AMD64
630 value_result->f = *(jfloat*)tos_addr;
631 #else
632 if (method->is_native()) {
633 jdouble d = *(jdouble*)tos_addr; // Result was in ST0 so need to convert to jfloat
634 value_result->f = (jfloat)d;
635 } else {
636 value_result->f = *(jfloat*)tos_addr;
637 }
638 #endif // AMD64
639 break;
640 }
641 case T_DOUBLE : value_result->d = *(jdouble*)tos_addr; break;
642 case T_VOID : /* Nothing to do */ break;
643 default : ShouldNotReachHere();
644 }
646 return type;
647 }
650 intptr_t* frame::interpreter_frame_tos_at(jint offset) const {
651 int index = (Interpreter::expr_offset_in_bytes(offset)/wordSize);
652 return &interpreter_frame_tos_address()[index];
653 }
655 #ifndef PRODUCT
657 #define DESCRIBE_FP_OFFSET(name) \
658 values.describe(frame_no, fp() + frame::name##_offset, #name)
660 void frame::describe_pd(FrameValues& values, int frame_no) {
661 if (is_interpreted_frame()) {
662 DESCRIBE_FP_OFFSET(interpreter_frame_sender_sp);
663 DESCRIBE_FP_OFFSET(interpreter_frame_last_sp);
664 DESCRIBE_FP_OFFSET(interpreter_frame_method);
665 DESCRIBE_FP_OFFSET(interpreter_frame_mdx);
666 DESCRIBE_FP_OFFSET(interpreter_frame_cache);
667 DESCRIBE_FP_OFFSET(interpreter_frame_locals);
668 DESCRIBE_FP_OFFSET(interpreter_frame_bcx);
669 DESCRIBE_FP_OFFSET(interpreter_frame_initial_sp);
670 }
671 }
672 #endif
674 intptr_t *frame::initial_deoptimization_info() {
675 // used to reset the saved FP
676 return fp();
677 }
679 intptr_t* frame::real_fp() const {
680 if (_cb != NULL) {
681 // use the frame size if valid
682 int size = _cb->frame_size();
683 if (size > 0) {
684 return unextended_sp() + size;
685 }
686 }
687 // else rely on fp()
688 assert(! is_compiled_frame(), "unknown compiled frame size");
689 return fp();
690 }