jdk

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/*
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 * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "classfile/javaClasses.inline.hpp"
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#include "classfile/vmSymbols.hpp"
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#include "code/codeCache.inline.hpp"
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#include "code/nmethod.inline.hpp"
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#include "code/vmreg.inline.hpp"
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#include "compiler/oopMap.inline.hpp"
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#include "gc/shared/continuationGCSupport.inline.hpp"
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#include "gc/shared/gc_globals.hpp"
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#include "gc/shared/barrierSet.hpp"
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#include "gc/shared/memAllocator.hpp"
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#include "gc/shared/threadLocalAllocBuffer.inline.hpp"
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#include "interpreter/interpreter.hpp"
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#include "jfr/jfrEvents.hpp"
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#include "logging/log.hpp"
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#include "logging/logStream.hpp"
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#include "oops/access.inline.hpp"
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#include "oops/method.inline.hpp"
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#include "oops/oopsHierarchy.hpp"
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#include "oops/objArrayOop.inline.hpp"
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#include "oops/stackChunkOop.inline.hpp"
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#include "prims/jvmtiThreadState.hpp"
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#include "runtime/arguments.hpp"
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#include "runtime/continuation.hpp"
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#include "runtime/continuationEntry.inline.hpp"
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#include "runtime/continuationHelper.inline.hpp"
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#include "runtime/continuationJavaClasses.inline.hpp"
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#include "runtime/continuationWrapper.inline.hpp"
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#include "runtime/frame.inline.hpp"
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#include "runtime/interfaceSupport.inline.hpp"
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#include "runtime/javaThread.inline.hpp"
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#include "runtime/jniHandles.inline.hpp"
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#include "runtime/keepStackGCProcessed.hpp"
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#include "runtime/orderAccess.hpp"
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#include "runtime/prefetch.inline.hpp"
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#include "runtime/smallRegisterMap.inline.hpp"
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#include "runtime/sharedRuntime.hpp"
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#include "runtime/stackChunkFrameStream.inline.hpp"
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#include "runtime/stackFrameStream.inline.hpp"
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#include "runtime/stackOverflow.hpp"
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#include "runtime/stackWatermarkSet.inline.hpp"
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#include "utilities/debug.hpp"
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#include "utilities/exceptions.hpp"
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#include "utilities/macros.hpp"
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#if INCLUDE_ZGC
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#include "gc/z/zStackChunkGCData.inline.hpp"
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#endif
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#include <type_traits>
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/*
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 * This file contains the implementation of continuation freezing (yield) and thawing (run).
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 *
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 * This code is very latency-critical and very hot. An ordinary and well-behaved server application
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 * would likely call these operations many thousands of times per second second, on every core.
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 *
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 * Freeze might be called every time the application performs any I/O operation, every time it
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 * acquires a j.u.c. lock, every time it takes a message from a queue, and thaw can be called
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 * multiple times in each of those cases, as it is called by the return barrier, which may be
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 * invoked on method return.
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 *
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 * The amortized budget for each of those two operations is ~100-150ns. That is why, for
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 * example, every effort is made to avoid Java-VM transitions as much as possible.
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 *
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 * On the fast path, all frames are known to be compiled, and the chunk requires no barriers
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 * and so frames simply copied, and the bottom-most one is patched.
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 * On the slow path, internal pointers in interpreted frames are de/relativized to/from offsets
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 * and absolute pointers, and barriers invoked.
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 */
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/************************************************
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Thread-stack layout on freeze/thaw.
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See corresponding stack-chunk layout in instanceStackChunkKlass.hpp
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            +----------------------------+
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            |      .                     |
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            |      .                     |
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            |      .                     |
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            |   carrier frames           |
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            |                            |
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            |----------------------------|
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            |                            |
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            |    Continuation.run        |
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            |                            |
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            |============================|
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            |    enterSpecial frame      |
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            |  pc                        |
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            |  rbp                       |
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            |  -----                     |
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        ^   |  int argsize               | = ContinuationEntry
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        |   |  oopDesc* cont             |
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        |   |  oopDesc* chunk            |
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        |   |  ContinuationEntry* parent |
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        |   |  ...                       |
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        |   |============================| <------ JavaThread::_cont_entry = entry->sp()
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        |   |  ? alignment word ?        |
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        |   |----------------------------| <--\
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        |   |                            |    |
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        |   |  ? caller stack args ?     |    |   argsize (might not be 2-word aligned) words
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Address |   |                            |    |   Caller is still in the chunk.
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        |   |----------------------------|    |
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        |   |  pc (? return barrier ?)   |    |  This pc contains the return barrier when the bottom-most frame
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        |   |  rbp                       |    |  isn't the last one in the continuation.
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        |   |                            |    |
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        |   |    frame                   |    |
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        |   |                            |    |
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            +----------------------------|     \__ Continuation frames to be frozen/thawed
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            |                            |     /
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            |    frame                   |    |
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            |                            |    |
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            |----------------------------|    |
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            |                            |    |
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            |    frame                   |    |
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            |                            |    |
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            |----------------------------| <--/
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            |                            |
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            |    doYield/safepoint stub  | When preempting forcefully, we could have a safepoint stub
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            |                            | instead of a doYield stub
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            |============================| <- the sp passed to freeze
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            |                            |
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            |  Native freeze/thaw frames |
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            |      .                     |
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            |      .                     |
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            |      .                     |
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            +----------------------------+
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************************************************/
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static const bool TEST_THAW_ONE_CHUNK_FRAME = false; // force thawing frames one-at-a-time for testing
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#define CONT_JFR false // emit low-level JFR events that count slow/fast path for continuation performance debugging only
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#if CONT_JFR
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  #define CONT_JFR_ONLY(code) code
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#else
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  #define CONT_JFR_ONLY(code)
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#endif
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// TODO: See AbstractAssembler::generate_stack_overflow_check,
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// Compile::bang_size_in_bytes(), m->as_SafePoint()->jvms()->interpreter_frame_size()
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// when we stack-bang, we need to update a thread field with the lowest (farthest) bang point.
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// Data invariants are defined by Continuation::debug_verify_continuation and Continuation::debug_verify_stack_chunk
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// Used to just annotatate cold/hot branches
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#define LIKELY(condition)   (condition)
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#define UNLIKELY(condition) (condition)
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// debugging functions
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#ifdef ASSERT
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extern "C" bool dbg_is_safe(const void* p, intptr_t errvalue); // address p is readable and *(intptr_t*)p != errvalue
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static void verify_continuation(oop continuation) { Continuation::debug_verify_continuation(continuation); }
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static void do_deopt_after_thaw(JavaThread* thread);
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static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st);
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static void log_frames(JavaThread* thread);
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static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st = tty);
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#define assert_pfl(p, ...) \
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do {                                           \
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  if (!(p)) {                                  \
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    JavaThread* t = JavaThread::active();      \
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    if (t->has_last_Java_frame()) {            \
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      tty->print_cr("assert(" #p ") failed:"); \
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      t->print_frame_layout();                 \
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    }                                          \
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  }                                            \
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  vmassert(p, __VA_ARGS__);                    \
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} while(0)
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#else
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static void verify_continuation(oop continuation) { }
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#define assert_pfl(p, ...)
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#endif
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// should match Continuation.preemptStatus() in Continuation.java
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enum freeze_result {
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  freeze_ok = 0,
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  freeze_ok_bottom = 1,
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  freeze_pinned_cs = 2,
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  freeze_pinned_native = 3,
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  freeze_pinned_monitor = 4,
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  freeze_exception = 5
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};
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const char* freeze_result_names[6] = {
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  "freeze_ok",
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  "freeze_ok_bottom",
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  "freeze_pinned_cs",
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  "freeze_pinned_native",
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  "freeze_pinned_monitor",
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  "freeze_exception"
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};
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static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint);
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template<typename ConfigT> static inline int freeze_internal(JavaThread* current, intptr_t* const sp);
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static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier);
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template<typename ConfigT> static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind);
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// Entry point to freeze. Transitions are handled manually
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// Called from gen_continuation_yield() in sharedRuntime_<cpu>.cpp through Continuation::freeze_entry();
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template<typename ConfigT>
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static JRT_BLOCK_ENTRY(int, freeze(JavaThread* current, intptr_t* sp))
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  assert(sp == current->frame_anchor()->last_Java_sp(), "");
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  if (current->raw_cont_fastpath() > current->last_continuation()->entry_sp() || current->raw_cont_fastpath() < sp) {
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    current->set_cont_fastpath(nullptr);
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  }
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  return ConfigT::freeze(current, sp);
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JRT_END
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JRT_LEAF(int, Continuation::prepare_thaw(JavaThread* thread, bool return_barrier))
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  return prepare_thaw_internal(thread, return_barrier);
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JRT_END
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template<typename ConfigT>
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static JRT_LEAF(intptr_t*, thaw(JavaThread* thread, int kind))
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  // TODO: JRT_LEAF and NoHandleMark is problematic for JFR events.
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  // vFrameStreamCommon allocates Handles in RegisterMap for continuations.
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  // JRT_ENTRY instead?
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  ResetNoHandleMark rnhm;
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  // we might modify the code cache via BarrierSetNMethod::nmethod_entry_barrier
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  MACOS_AARCH64_ONLY(ThreadWXEnable __wx(WXWrite, thread));
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  return ConfigT::thaw(thread, (Continuation::thaw_kind)kind);
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JRT_END
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JVM_ENTRY(jint, CONT_isPinned0(JNIEnv* env, jobject cont_scope)) {
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  JavaThread* thread = JavaThread::thread_from_jni_environment(env);
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  return is_pinned0(thread, JNIHandles::resolve(cont_scope), false);
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}
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JVM_END
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///////////
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enum class oop_kind { NARROW, WIDE };
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template <oop_kind oops, typename BarrierSetT>
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class Config {
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public:
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  typedef Config<oops, BarrierSetT> SelfT;
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  using OopT = std::conditional_t<oops == oop_kind::NARROW, narrowOop, oop>;
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  static int freeze(JavaThread* thread, intptr_t* const sp) {
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    return freeze_internal<SelfT>(thread, sp);
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  }
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  static intptr_t* thaw(JavaThread* thread, Continuation::thaw_kind kind) {
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    return thaw_internal<SelfT>(thread, kind);
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  }
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};
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static bool stack_overflow_check(JavaThread* thread, size_t size, address sp) {
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  const size_t page_size = os::vm_page_size();
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  if (size > page_size) {
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    if (sp - size < thread->stack_overflow_state()->shadow_zone_safe_limit()) {
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      return false;
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    }
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  }
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  return true;
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}
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#ifdef ASSERT
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static oop get_continuation(JavaThread* thread) {
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  assert(thread != nullptr, "");
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  assert(thread->threadObj() != nullptr, "");
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  return java_lang_Thread::continuation(thread->threadObj());
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}
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inline void clear_anchor(JavaThread* thread) {
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  thread->frame_anchor()->clear();
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}
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static void set_anchor(JavaThread* thread, intptr_t* sp) {
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  address pc = ContinuationHelper::return_address_at(
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                 sp - frame::sender_sp_ret_address_offset());
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  assert(pc != nullptr, "");
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  JavaFrameAnchor* anchor = thread->frame_anchor();
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  anchor->set_last_Java_sp(sp);
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  anchor->set_last_Java_pc(pc);
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  ContinuationHelper::set_anchor_pd(anchor, sp);
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  assert(thread->has_last_Java_frame(), "");
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  assert(thread->last_frame().cb() != nullptr, "");
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}
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#endif // ASSERT
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static void set_anchor_to_entry(JavaThread* thread, ContinuationEntry* entry) {
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  JavaFrameAnchor* anchor = thread->frame_anchor();
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  anchor->set_last_Java_sp(entry->entry_sp());
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  anchor->set_last_Java_pc(entry->entry_pc());
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  ContinuationHelper::set_anchor_to_entry_pd(anchor, entry);
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  assert(thread->has_last_Java_frame(), "");
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  assert(thread->last_frame().cb() != nullptr, "");
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}
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#if CONT_JFR
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class FreezeThawJfrInfo : public StackObj {
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  short _e_size;
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  short _e_num_interpreted_frames;
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 public:
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  FreezeThawJfrInfo() : _e_size(0), _e_num_interpreted_frames(0) {}
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  inline void record_interpreted_frame() { _e_num_interpreted_frames++; }
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  inline void record_size_copied(int size) { _e_size += size << LogBytesPerWord; }
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  template<typename Event> void post_jfr_event(Event *e, oop continuation, JavaThread* jt);
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};
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template<typename Event> void FreezeThawJfrInfo::post_jfr_event(Event* e, oop continuation, JavaThread* jt) {
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  if (e->should_commit()) {
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    log_develop_trace(continuations)("JFR event: iframes: %d size: %d", _e_num_interpreted_frames, _e_size);
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    e->set_carrierThread(JFR_JVM_THREAD_ID(jt));
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    e->set_continuationClass(continuation->klass());
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    e->set_interpretedFrames(_e_num_interpreted_frames);
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    e->set_size(_e_size);
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    e->commit();
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  }
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}
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#endif // CONT_JFR
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/////////////// FREEZE ////
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class FreezeBase : public StackObj {
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protected:
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  JavaThread* const _thread;
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  ContinuationWrapper& _cont;
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  bool _barriers; // only set when we allocate a chunk
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  const bool _preempt; // used only on the slow path
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  const intptr_t * const _frame_sp; // Top frame sp for this freeze
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  intptr_t* _bottom_address;
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  int _freeze_size; // total size of all frames plus metadata in words.
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  int _total_align_size;
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  intptr_t* _cont_stack_top;
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  intptr_t* _cont_stack_bottom;
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  CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
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#ifdef ASSERT
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  intptr_t* _orig_chunk_sp;
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  int _fast_freeze_size;
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  bool _empty;
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#endif
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  JvmtiSampledObjectAllocEventCollector* _jvmti_event_collector;
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  NOT_PRODUCT(int _frames;)
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  DEBUG_ONLY(intptr_t* _last_write;)
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  inline FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp);
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public:
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  NOINLINE freeze_result freeze_slow();
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  void freeze_fast_existing_chunk();
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  CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
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  void set_jvmti_event_collector(JvmtiSampledObjectAllocEventCollector* jsoaec) { _jvmti_event_collector = jsoaec; }
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  inline int size_if_fast_freeze_available();
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392
#ifdef ASSERT
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  bool check_valid_fast_path();
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#endif
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protected:
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  inline void init_rest();
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  void throw_stack_overflow_on_humongous_chunk();
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  // fast path
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  inline void copy_to_chunk(intptr_t* from, intptr_t* to, int size);
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  inline void unwind_frames();
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  inline void patch_stack_pd(intptr_t* frame_sp, intptr_t* heap_sp);
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405
  // slow path
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  virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) = 0;
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  int cont_size() { return pointer_delta_as_int(_cont_stack_bottom, _cont_stack_top); }
409

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private:
411
  // slow path
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  frame freeze_start_frame();
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  frame freeze_start_frame_safepoint_stub(frame f);
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  NOINLINE freeze_result recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top);
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  inline frame freeze_start_frame_yield_stub(frame f);
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  template<typename FKind>
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  inline freeze_result recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize);
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  inline void before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame);
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  inline void after_freeze_java_frame(const frame& hf, bool is_bottom_frame);
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  freeze_result finalize_freeze(const frame& callee, frame& caller, int argsize);
421
  void patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame);
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  NOINLINE freeze_result recurse_freeze_interpreted_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
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  freeze_result recurse_freeze_compiled_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
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  NOINLINE freeze_result recurse_freeze_stub_frame(frame& f, frame& caller);
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  NOINLINE void finish_freeze(const frame& f, const frame& top);
426

427
  inline bool stack_overflow();
428

429
  static frame sender(const frame& f) { return f.is_interpreted_frame() ? sender<ContinuationHelper::InterpretedFrame>(f)
430
                                                                        : sender<ContinuationHelper::NonInterpretedUnknownFrame>(f); }
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  template<typename FKind> static inline frame sender(const frame& f);
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  template<typename FKind> frame new_heap_frame(frame& f, frame& caller);
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  inline void set_top_frame_metadata_pd(const frame& hf);
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  inline void patch_pd(frame& callee, const frame& caller);
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  void adjust_interpreted_frame_unextended_sp(frame& f);
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  static inline void relativize_interpreted_frame_metadata(const frame& f, const frame& hf);
437

438
protected:
439
  void freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated));
440
  bool freeze_fast_new_chunk(stackChunkOop chunk);
441
};
442

443
template <typename ConfigT>
444
class Freeze : public FreezeBase {
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private:
446
  stackChunkOop allocate_chunk(size_t stack_size, int argsize_md);
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public:
449
  inline Freeze(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp)
450
    : FreezeBase(thread, cont, frame_sp) {}
451

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  freeze_result try_freeze_fast();
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protected:
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  virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) override { return allocate_chunk(stack_size, argsize_md); }
456
};
457

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FreezeBase::FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp) :
459
    _thread(thread), _cont(cont), _barriers(false), _preempt(false), _frame_sp(frame_sp) {
460
  DEBUG_ONLY(_jvmti_event_collector = nullptr;)
461

462
  assert(_thread != nullptr, "");
463
  assert(_thread->last_continuation()->entry_sp() == _cont.entrySP(), "");
464

465
  DEBUG_ONLY(_cont.entry()->verify_cookie();)
466

467
  assert(!Interpreter::contains(_cont.entryPC()), "");
468

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  _bottom_address = _cont.entrySP() - _cont.entry_frame_extension();
470
#ifdef _LP64
471
  if (((intptr_t)_bottom_address & 0xf) != 0) {
472
    _bottom_address--;
473
  }
474
  assert(is_aligned(_bottom_address, frame::frame_alignment), "");
475
#endif
476

477
  log_develop_trace(continuations)("bottom_address: " INTPTR_FORMAT " entrySP: " INTPTR_FORMAT " argsize: " PTR_FORMAT,
478
                p2i(_bottom_address), p2i(_cont.entrySP()), (_cont.entrySP() - _bottom_address) << LogBytesPerWord);
479
  assert(_bottom_address != nullptr, "");
480
  assert(_bottom_address <= _cont.entrySP(), "");
481
  DEBUG_ONLY(_last_write = nullptr;)
482

483
  assert(_cont.chunk_invariant(), "");
484
  assert(!Interpreter::contains(_cont.entryPC()), "");
485
#if !defined(PPC64) || defined(ZERO)
486
  static const int doYield_stub_frame_size = frame::metadata_words;
487
#else
488
  static const int doYield_stub_frame_size = frame::native_abi_reg_args_size >> LogBytesPerWord;
489
#endif
490
  assert(SharedRuntime::cont_doYield_stub()->frame_size() == doYield_stub_frame_size, "");
491

492
  // properties of the continuation on the stack; all sizes are in words
493
  _cont_stack_top    = frame_sp + doYield_stub_frame_size; // we don't freeze the doYield stub frame
494
  _cont_stack_bottom = _cont.entrySP() + (_cont.argsize() == 0 ? frame::metadata_words_at_top : 0)
495
      - ContinuationHelper::frame_align_words(_cont.argsize()); // see alignment in thaw
496

497
  log_develop_trace(continuations)("freeze size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
498
    cont_size(), _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
499
  assert(cont_size() > 0, "");
500
}
501

502
void FreezeBase::init_rest() { // we want to postpone some initialization after chunk handling
503
  _freeze_size = 0;
504
  _total_align_size = 0;
505
  NOT_PRODUCT(_frames = 0;)
506
}
507

508
void FreezeBase::copy_to_chunk(intptr_t* from, intptr_t* to, int size) {
509
  stackChunkOop chunk = _cont.tail();
510
  chunk->copy_from_stack_to_chunk(from, to, size);
511
  CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
512

513
#ifdef ASSERT
514
  if (_last_write != nullptr) {
515
    assert(_last_write == to + size, "Missed a spot: _last_write: " INTPTR_FORMAT " to+size: " INTPTR_FORMAT
516
        " stack_size: %d _last_write offset: " PTR_FORMAT " to+size: " PTR_FORMAT, p2i(_last_write), p2i(to+size),
517
        chunk->stack_size(), _last_write-chunk->start_address(), to+size-chunk->start_address());
518
    _last_write = to;
519
  }
520
#endif
521
}
522

523
// Called _after_ the last possible safepoint during the freeze operation (chunk allocation)
524
void FreezeBase::unwind_frames() {
525
  ContinuationEntry* entry = _cont.entry();
526
  entry->flush_stack_processing(_thread);
527
  set_anchor_to_entry(_thread, entry);
528
}
529

530
template <typename ConfigT>
531
freeze_result Freeze<ConfigT>::try_freeze_fast() {
532
  assert(_thread->thread_state() == _thread_in_vm, "");
533
  assert(_thread->cont_fastpath(), "");
534

535
  DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
536
  assert(_fast_freeze_size == 0, "");
537

538
  stackChunkOop chunk = allocate_chunk(cont_size() + frame::metadata_words, _cont.argsize() + frame::metadata_words_at_top);
539
  if (freeze_fast_new_chunk(chunk)) {
540
    return freeze_ok;
541
  }
542
  if (_thread->has_pending_exception()) {
543
    return freeze_exception;
544
  }
545

546
  // TODO R REMOVE when deopt change is fixed
547
  assert(!_thread->cont_fastpath() || _barriers, "");
548
  log_develop_trace(continuations)("-- RETRYING SLOW --");
549
  return freeze_slow();
550
}
551

552
// Returns size needed if the continuation fits, otherwise 0.
553
int FreezeBase::size_if_fast_freeze_available() {
554
  stackChunkOop chunk = _cont.tail();
555
  if (chunk == nullptr || chunk->is_gc_mode() || chunk->requires_barriers() || chunk->has_mixed_frames()) {
556
    log_develop_trace(continuations)("chunk available %s", chunk == nullptr ? "no chunk" : "chunk requires barriers");
557
    return 0;
558
  }
559

560
  int total_size_needed = cont_size();
561
  const int chunk_sp = chunk->sp();
562

563
  // argsize can be nonzero if we have a caller, but the caller could be in a non-empty parent chunk,
564
  // so we subtract it only if we overlap with the caller, i.e. the current chunk isn't empty.
565
  // Consider leaving the chunk's argsize set when emptying it and removing the following branch,
566
  // although that would require changing stackChunkOopDesc::is_empty
567
  if (!chunk->is_empty()) {
568
    total_size_needed -= _cont.argsize() + frame::metadata_words_at_top;
569
  }
570

571
  int chunk_free_room = chunk_sp - frame::metadata_words_at_bottom;
572
  bool available = chunk_free_room >= total_size_needed;
573
  log_develop_trace(continuations)("chunk available: %s size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
574
    available ? "yes" : "no" , total_size_needed, _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
575
  return available ? total_size_needed : 0;
576
}
577

578
void FreezeBase::freeze_fast_existing_chunk() {
579
  stackChunkOop chunk = _cont.tail();
580

581
  DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
582
  assert(_fast_freeze_size > 0, "");
583

584
  if (!chunk->is_empty()) { // we are copying into a non-empty chunk
585
    DEBUG_ONLY(_empty = false;)
586
    DEBUG_ONLY(_orig_chunk_sp = chunk->sp_address();)
587
#ifdef ASSERT
588
    {
589
      intptr_t* retaddr_slot = (chunk->sp_address()
590
                                - frame::sender_sp_ret_address_offset());
591
      assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
592
             "unexpected saved return address");
593
    }
594
#endif
595

596
    // the chunk's sp before the freeze, adjusted to point beyond the stack-passed arguments in the topmost frame
597
    // we overlap; we'll overwrite the chunk's top frame's callee arguments
598
    const int chunk_start_sp = chunk->sp() + _cont.argsize() + frame::metadata_words_at_top;
599
    assert(chunk_start_sp <= chunk->stack_size(), "sp not pointing into stack");
600

601
    // increase max_size by what we're freezing minus the overlap
602
    chunk->set_max_thawing_size(chunk->max_thawing_size() + cont_size() - _cont.argsize() - frame::metadata_words_at_top);
603

604
    intptr_t* const bottom_sp = _cont_stack_bottom - _cont.argsize() - frame::metadata_words_at_top;
605
    assert(bottom_sp == _bottom_address, "");
606
    // Because the chunk isn't empty, we know there's a caller in the chunk, therefore the bottom-most frame
607
    // should have a return barrier (installed back when we thawed it).
608
#ifdef ASSERT
609
    {
610
      intptr_t* retaddr_slot = (bottom_sp
611
                                - frame::sender_sp_ret_address_offset());
612
      assert(ContinuationHelper::return_address_at(retaddr_slot)
613
             == StubRoutines::cont_returnBarrier(),
614
             "should be the continuation return barrier");
615
    }
616
#endif
617
    // We copy the fp from the chunk back to the stack because it contains some caller data,
618
    // including, possibly, an oop that might have gone stale since we thawed.
619
    patch_stack_pd(bottom_sp, chunk->sp_address());
620
    // we don't patch the return pc at this time, so as not to make the stack unwalkable for async walks
621

622
    freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
623
  } else { // the chunk is empty
624
    const int chunk_start_sp = chunk->stack_size();
625

626
    DEBUG_ONLY(_empty = true;)
627
    DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
628

629
    chunk->set_max_thawing_size(cont_size());
630
    chunk->set_bottom(chunk_start_sp - _cont.argsize() - frame::metadata_words_at_top);
631
    chunk->set_sp(chunk->bottom());
632

633
    freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
634
  }
635
}
636

637
bool FreezeBase::freeze_fast_new_chunk(stackChunkOop chunk) {
638
  DEBUG_ONLY(_empty = true;)
639

640
  // Install new chunk
641
  _cont.set_tail(chunk);
642

643
  if (UNLIKELY(chunk == nullptr || !_thread->cont_fastpath() || _barriers)) { // OOME/probably humongous
644
    log_develop_trace(continuations)("Retrying slow. Barriers: %d", _barriers);
645
    return false;
646
  }
647

648
  chunk->set_max_thawing_size(cont_size());
649

650
  // in a fresh chunk, we freeze *with* the bottom-most frame's stack arguments.
651
  // They'll then be stored twice: in the chunk and in the parent chunk's top frame
652
  const int chunk_start_sp = cont_size() + frame::metadata_words;
653
  assert(chunk_start_sp == chunk->stack_size(), "");
654

655
  DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
656

657
  freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA true));
658

659
  return true;
660
}
661

662
void FreezeBase::freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated)) {
663
  assert(chunk != nullptr, "");
664
  assert(!chunk->has_mixed_frames(), "");
665
  assert(!chunk->is_gc_mode(), "");
666
  assert(!chunk->has_bitmap(), "");
667
  assert(!chunk->requires_barriers(), "");
668
  assert(chunk == _cont.tail(), "");
669

670
  // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
671
  // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
672
  // will either see no continuation on the stack, or a consistent chunk.
673
  unwind_frames();
674

675
  log_develop_trace(continuations)("freeze_fast start: chunk " INTPTR_FORMAT " size: %d orig sp: %d argsize: %d",
676
    p2i((oopDesc*)chunk), chunk->stack_size(), chunk_start_sp, _cont.argsize());
677
  assert(chunk_start_sp <= chunk->stack_size(), "");
678
  assert(chunk_start_sp >= cont_size(), "no room in the chunk");
679

680
  const int chunk_new_sp = chunk_start_sp - cont_size(); // the chunk's new sp, after freeze
681
  assert(!(_fast_freeze_size > 0) || _orig_chunk_sp - (chunk->start_address() + chunk_new_sp) == _fast_freeze_size, "");
682

683
  intptr_t* chunk_top = chunk->start_address() + chunk_new_sp;
684
#ifdef ASSERT
685
  if (!_empty) {
686
    intptr_t* retaddr_slot = (_orig_chunk_sp
687
                              - frame::sender_sp_ret_address_offset());
688
    assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
689
           "unexpected saved return address");
690
  }
691
#endif
692

693
  log_develop_trace(continuations)("freeze_fast start: " INTPTR_FORMAT " sp: %d chunk_top: " INTPTR_FORMAT,
694
                              p2i(chunk->start_address()), chunk_new_sp, p2i(chunk_top));
695
  intptr_t* from = _cont_stack_top - frame::metadata_words_at_bottom;
696
  intptr_t* to   = chunk_top - frame::metadata_words_at_bottom;
697
  copy_to_chunk(from, to, cont_size() + frame::metadata_words_at_bottom);
698
  // Because we're not patched yet, the chunk is now in a bad state
699

700
  // patch return pc of the bottom-most frozen frame (now in the chunk)
701
  // with the actual caller's return address
702
  intptr_t* chunk_bottom_retaddr_slot = (chunk_top + cont_size()
703
                                         - _cont.argsize()
704
                                         - frame::metadata_words_at_top
705
                                         - frame::sender_sp_ret_address_offset());
706
#ifdef ASSERT
707
  if (!_empty) {
708
    assert(ContinuationHelper::return_address_at(chunk_bottom_retaddr_slot)
709
           == StubRoutines::cont_returnBarrier(),
710
           "should be the continuation return barrier");
711
  }
712
#endif
713
  ContinuationHelper::patch_return_address_at(chunk_bottom_retaddr_slot,
714
                                              chunk->pc());
715

716
  // We're always writing to a young chunk, so the GC can't see it until the next safepoint.
717
  chunk->set_sp(chunk_new_sp);
718
  // set chunk->pc to the return address of the topmost frame in the chunk
719
  chunk->set_pc(ContinuationHelper::return_address_at(
720
                  _cont_stack_top - frame::sender_sp_ret_address_offset()));
721

722
  _cont.write();
723

724
  log_develop_trace(continuations)("FREEZE CHUNK #" INTPTR_FORMAT " (young)", _cont.hash());
725
  LogTarget(Trace, continuations) lt;
726
  if (lt.develop_is_enabled()) {
727
    LogStream ls(lt);
728
    chunk->print_on(true, &ls);
729
  }
730

731
  // Verification
732
  assert(_cont.chunk_invariant(), "");
733
  chunk->verify();
734

735
#if CONT_JFR
736
  EventContinuationFreezeFast e;
737
  if (e.should_commit()) {
738
    e.set_id(cast_from_oop<u8>(chunk));
739
    DEBUG_ONLY(e.set_allocate(chunk_is_allocated);)
740
    e.set_size(cont_size() << LogBytesPerWord);
741
    e.commit();
742
  }
743
#endif
744
}
745

746
NOINLINE freeze_result FreezeBase::freeze_slow() {
747
#ifdef ASSERT
748
  ResourceMark rm;
749
#endif
750

751
  log_develop_trace(continuations)("freeze_slow  #" INTPTR_FORMAT, _cont.hash());
752
  assert(_thread->thread_state() == _thread_in_vm || _thread->thread_state() == _thread_blocked, "");
753

754
#if CONT_JFR
755
  EventContinuationFreezeSlow e;
756
  if (e.should_commit()) {
757
    e.set_id(cast_from_oop<u8>(_cont.continuation()));
758
    e.commit();
759
  }
760
#endif
761

762
  init_rest();
763

764
  HandleMark hm(Thread::current());
765

766
  frame f = freeze_start_frame();
767

768
  LogTarget(Debug, continuations) lt;
769
  if (lt.develop_is_enabled()) {
770
    LogStream ls(lt);
771
    f.print_on(&ls);
772
  }
773

774
  frame caller; // the frozen caller in the chunk
775
  freeze_result res = recurse_freeze(f, caller, 0, false, true);
776

777
  if (res == freeze_ok) {
778
    finish_freeze(f, caller);
779
    _cont.write();
780
  }
781

782
  return res;
783
}
784

785
frame FreezeBase::freeze_start_frame() {
786
  frame f = _thread->last_frame();
787
  if (LIKELY(!_preempt)) {
788
    return freeze_start_frame_yield_stub(f);
789
  } else {
790
    return freeze_start_frame_safepoint_stub(f);
791
  }
792
}
793

794
frame FreezeBase::freeze_start_frame_yield_stub(frame f) {
795
  assert(SharedRuntime::cont_doYield_stub()->contains(f.pc()), "must be");
796
  f = sender<ContinuationHelper::NonInterpretedUnknownFrame>(f);
797
  assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
798
  return f;
799
}
800

801
frame FreezeBase::freeze_start_frame_safepoint_stub(frame f) {
802
#if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
803
  f.set_fp(f.real_fp()); // f.set_fp(*Frame::callee_link_address(f)); // ????
804
#else
805
  Unimplemented();
806
#endif
807
  if (!Interpreter::contains(f.pc())) {
808
    assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
809
    assert(f.oop_map() != nullptr, "must be");
810

811
    if (Interpreter::contains(ContinuationHelper::StubFrame::return_pc(f))) {
812
      f = sender<ContinuationHelper::StubFrame>(f); // Safepoint stub in interpreter
813
    }
814
  }
815
  assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
816
  return f;
817
}
818

819
// The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
820
NOINLINE freeze_result FreezeBase::recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top) {
821
  assert(f.unextended_sp() < _bottom_address, ""); // see recurse_freeze_java_frame
822
  assert(f.is_interpreted_frame() || ((top && _preempt) == ContinuationHelper::Frame::is_stub(f.cb())), "");
823

824
  if (stack_overflow()) {
825
    return freeze_exception;
826
  }
827

828
  if (f.is_compiled_frame()) {
829
    if (UNLIKELY(f.oop_map() == nullptr)) {
830
      // special native frame
831
      return freeze_pinned_native;
832
    }
833
    return recurse_freeze_compiled_frame(f, caller, callee_argsize, callee_interpreted);
834
  } else if (f.is_interpreted_frame()) {
835
    assert((_preempt && top) || !f.interpreter_frame_method()->is_native(), "");
836
    if (_preempt && top && f.interpreter_frame_method()->is_native()) {
837
      // int native entry
838
      return freeze_pinned_native;
839
    }
840

841
    return recurse_freeze_interpreted_frame(f, caller, callee_argsize, callee_interpreted);
842
  } else if (_preempt && top && ContinuationHelper::Frame::is_stub(f.cb())) {
843
    return recurse_freeze_stub_frame(f, caller);
844
  } else {
845
    return freeze_pinned_native;
846
  }
847
}
848

849
// The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
850
// See also StackChunkFrameStream<frame_kind>::frame_size()
851
template<typename FKind>
852
inline freeze_result FreezeBase::recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize) {
853
  assert(FKind::is_instance(f), "");
854

855
  assert(fsize > 0, "");
856
  assert(argsize >= 0, "");
857
  _freeze_size += fsize;
858
  NOT_PRODUCT(_frames++;)
859

860
  assert(FKind::frame_bottom(f) <= _bottom_address, "");
861

862
  // We don't use FKind::frame_bottom(f) == _bottom_address because on x64 there's sometimes an extra word between
863
  // enterSpecial and an interpreted frame
864
  if (FKind::frame_bottom(f) >= _bottom_address - 1) {
865
    return finalize_freeze(f, caller, argsize); // recursion end
866
  } else {
867
    frame senderf = sender<FKind>(f);
868
    assert(FKind::interpreted || senderf.sp() == senderf.unextended_sp(), "");
869
    freeze_result result = recurse_freeze(senderf, caller, argsize, FKind::interpreted, false); // recursive call
870
    return result;
871
  }
872
}
873

874
inline void FreezeBase::before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame) {
875
  LogTarget(Trace, continuations) lt;
876
  if (lt.develop_is_enabled()) {
877
    LogStream ls(lt);
878
    ls.print_cr("======== FREEZING FRAME interpreted: %d bottom: %d", f.is_interpreted_frame(), is_bottom_frame);
879
    ls.print_cr("fsize: %d argsize: %d", fsize, argsize);
880
    f.print_value_on(&ls, nullptr);
881
  }
882
  assert(caller.is_interpreted_frame() == Interpreter::contains(caller.pc()), "");
883
}
884

885
inline void FreezeBase::after_freeze_java_frame(const frame& hf, bool is_bottom_frame) {
886
  LogTarget(Trace, continuations) lt;
887
  if (lt.develop_is_enabled()) {
888
    LogStream ls(lt);
889
    DEBUG_ONLY(hf.print_value_on(&ls, nullptr);)
890
    assert(hf.is_heap_frame(), "should be");
891
    DEBUG_ONLY(print_frame_layout(hf, false, &ls);)
892
    if (is_bottom_frame) {
893
      ls.print_cr("bottom h-frame:");
894
      hf.print_on(&ls);
895
    }
896
  }
897
}
898

899
// The parameter argsize_md includes metadata that has to be part of caller/callee overlap.
900
// See also StackChunkFrameStream<frame_kind>::frame_size()
901
freeze_result FreezeBase::finalize_freeze(const frame& callee, frame& caller, int argsize_md) {
902
  int argsize = argsize_md - frame::metadata_words_at_top;
903
  assert(callee.is_interpreted_frame()
904
    || callee.cb()->as_nmethod()->is_osr_method()
905
    || argsize == _cont.argsize(), "argsize: %d cont.argsize: %d", argsize, _cont.argsize());
906
  log_develop_trace(continuations)("bottom: " INTPTR_FORMAT " count %d size: %d argsize: %d",
907
    p2i(_bottom_address), _frames, _freeze_size << LogBytesPerWord, argsize);
908

909
  LogTarget(Trace, continuations) lt;
910

911
#ifdef ASSERT
912
  bool empty = _cont.is_empty();
913
  log_develop_trace(continuations)("empty: %d", empty);
914
#endif
915

916
  stackChunkOop chunk = _cont.tail();
917

918
  assert(chunk == nullptr || (chunk->max_thawing_size() == 0) == chunk->is_empty(), "");
919

920
  _freeze_size += frame::metadata_words; // for top frame's metadata
921

922
  int overlap = 0; // the args overlap the caller -- if there is one in this chunk and is of the same kind
923
  int unextended_sp = -1;
924
  if (chunk != nullptr) {
925
    if (!chunk->is_empty()) {
926
      StackChunkFrameStream<ChunkFrames::Mixed> last(chunk);
927
      unextended_sp = chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp());
928
      bool top_interpreted = Interpreter::contains(chunk->pc());
929
      if (callee.is_interpreted_frame() == top_interpreted) {
930
        overlap = argsize_md;
931
      }
932
    } else {
933
      unextended_sp = chunk->stack_size() - frame::metadata_words_at_top;
934
    }
935
  }
936

937
  log_develop_trace(continuations)("finalize _size: %d overlap: %d unextended_sp: %d", _freeze_size, overlap, unextended_sp);
938

939
  _freeze_size -= overlap;
940
  assert(_freeze_size >= 0, "");
941

942
  assert(chunk == nullptr || chunk->is_empty()
943
          || unextended_sp == chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp()), "");
944
  assert(chunk != nullptr || unextended_sp < _freeze_size, "");
945

946
  // _barriers can be set to true by an allocation in freeze_fast, in which case the chunk is available
947
  bool allocated_old_in_freeze_fast = _barriers;
948
  assert(!allocated_old_in_freeze_fast || (unextended_sp >= _freeze_size && chunk->is_empty()),
949
    "Chunk allocated in freeze_fast is of insufficient size "
950
    "unextended_sp: %d size: %d is_empty: %d", unextended_sp, _freeze_size, chunk->is_empty());
951
  assert(!allocated_old_in_freeze_fast || (!UseZGC && !UseG1GC), "Unexpected allocation");
952

953
  DEBUG_ONLY(bool empty_chunk = true);
954
  if (unextended_sp < _freeze_size || chunk->is_gc_mode() || (!allocated_old_in_freeze_fast && chunk->requires_barriers())) {
955
    // ALLOCATE NEW CHUNK
956

957
    if (lt.develop_is_enabled()) {
958
      LogStream ls(lt);
959
      if (chunk == nullptr) {
960
        ls.print_cr("no chunk");
961
      } else {
962
        ls.print_cr("chunk barriers: %d _size: %d free size: %d",
963
          chunk->requires_barriers(), _freeze_size, chunk->sp() - frame::metadata_words);
964
        chunk->print_on(&ls);
965
      }
966
    }
967

968
    _freeze_size += overlap; // we're allocating a new chunk, so no overlap
969
    // overlap = 0;
970

971
    chunk = allocate_chunk_slow(_freeze_size, argsize_md);
972
    if (chunk == nullptr) {
973
      return freeze_exception;
974
    }
975

976
    // Install new chunk
977
    _cont.set_tail(chunk);
978
    assert(chunk->is_empty(), "");
979
  } else {
980
    // REUSE EXISTING CHUNK
981
    log_develop_trace(continuations)("Reusing chunk mixed: %d empty: %d", chunk->has_mixed_frames(), chunk->is_empty());
982
    if (chunk->is_empty()) {
983
      int sp = chunk->stack_size() - argsize_md;
984
      chunk->set_sp(sp);
985
      chunk->set_bottom(sp);
986
      _freeze_size += overlap;
987
      assert(chunk->max_thawing_size() == 0, "");
988
    } DEBUG_ONLY(else empty_chunk = false;)
989
  }
990
  assert(!chunk->is_gc_mode(), "");
991
  assert(!chunk->has_bitmap(), "");
992
  chunk->set_has_mixed_frames(true);
993

994
  assert(chunk->requires_barriers() == _barriers, "");
995
  assert(!_barriers || chunk->is_empty(), "");
996

997
  assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).is_done(), "");
998
  assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame().is_empty(), "");
999

1000
  // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
1001
  // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
1002
  // will either see no continuation or a consistent chunk.
1003
  unwind_frames();
1004

1005
  chunk->set_max_thawing_size(chunk->max_thawing_size() + _freeze_size - frame::metadata_words);
1006

1007
  if (lt.develop_is_enabled()) {
1008
    LogStream ls(lt);
1009
    ls.print_cr("top chunk:");
1010
    chunk->print_on(&ls);
1011
  }
1012

1013
  // The topmost existing frame in the chunk; or an empty frame if the chunk is empty
1014
  caller = StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame();
1015

1016
  DEBUG_ONLY(_last_write = caller.unextended_sp() + (empty_chunk ? argsize_md : overlap);)
1017

1018
  assert(chunk->is_in_chunk(_last_write - _freeze_size),
1019
    "last_write-size: " INTPTR_FORMAT " start: " INTPTR_FORMAT, p2i(_last_write-_freeze_size), p2i(chunk->start_address()));
1020
#ifdef ASSERT
1021
  if (lt.develop_is_enabled()) {
1022
    LogStream ls(lt);
1023
    ls.print_cr("top hframe before (freeze):");
1024
    assert(caller.is_heap_frame(), "should be");
1025
    caller.print_on(&ls);
1026
  }
1027

1028
  assert(!empty || Continuation::is_continuation_entry_frame(callee, nullptr), "");
1029

1030
  frame entry = sender(callee);
1031

1032
  assert(Continuation::is_return_barrier_entry(entry.pc()) || Continuation::is_continuation_enterSpecial(entry), "");
1033
  assert(callee.is_interpreted_frame() || entry.sp() == entry.unextended_sp(), "");
1034
#endif
1035

1036
  return freeze_ok_bottom;
1037
}
1038

1039
void FreezeBase::patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame) {
1040
  if (is_bottom_frame) {
1041
    // If we're the bottom frame, we need to replace the return barrier with the real
1042
    // caller's pc.
1043
    address last_pc = caller.pc();
1044
    assert((last_pc == nullptr) == _cont.tail()->is_empty(), "");
1045
    ContinuationHelper::Frame::patch_pc(caller, last_pc);
1046
  } else {
1047
    assert(!caller.is_empty(), "");
1048
  }
1049

1050
  patch_pd(hf, caller);
1051

1052
  if (f.is_interpreted_frame()) {
1053
    assert(hf.is_heap_frame(), "should be");
1054
    ContinuationHelper::InterpretedFrame::patch_sender_sp(hf, caller);
1055
  }
1056

1057
#ifdef ASSERT
1058
  if (hf.is_compiled_frame()) {
1059
    if (f.is_deoptimized_frame()) { // TODO DEOPT: long term solution: unroll on freeze and patch pc
1060
      log_develop_trace(continuations)("Freezing deoptimized frame");
1061
      assert(f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
1062
      assert(f.cb()->as_nmethod()->is_deopt_pc(ContinuationHelper::Frame::real_pc(f)), "");
1063
    }
1064
  }
1065
#endif
1066
}
1067

1068
#ifdef ASSERT
1069
static void verify_frame_top(const frame& f, intptr_t* top) {
1070
  ResourceMark rm;
1071
  InterpreterOopMap mask;
1072
  f.interpreted_frame_oop_map(&mask);
1073
  assert(top <= ContinuationHelper::InterpretedFrame::frame_top(f, &mask),
1074
         "frame_top: " INTPTR_FORMAT " Interpreted::frame_top: " INTPTR_FORMAT,
1075
           p2i(top), p2i(ContinuationHelper::InterpretedFrame::frame_top(f, &mask)));
1076
}
1077
#endif // ASSERT
1078

1079
// The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1080
// See also StackChunkFrameStream<frame_kind>::frame_size()
1081
NOINLINE freeze_result FreezeBase::recurse_freeze_interpreted_frame(frame& f, frame& caller,
1082
                                                                    int callee_argsize /* incl. metadata */,
1083
                                                                    bool callee_interpreted) {
1084
  adjust_interpreted_frame_unextended_sp(f);
1085

1086
  // The frame's top never includes the stack arguments to the callee
1087
  intptr_t* const stack_frame_top = ContinuationHelper::InterpretedFrame::frame_top(f, callee_argsize, callee_interpreted);
1088
  intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
1089
  const int fsize = pointer_delta_as_int(stack_frame_bottom, stack_frame_top);
1090

1091
  DEBUG_ONLY(verify_frame_top(f, stack_frame_top));
1092

1093
  Method* frame_method = ContinuationHelper::Frame::frame_method(f);
1094
  // including metadata between f and its args
1095
  const int argsize = ContinuationHelper::InterpretedFrame::stack_argsize(f) + frame::metadata_words_at_top;
1096

1097
  log_develop_trace(continuations)("recurse_freeze_interpreted_frame %s _size: %d fsize: %d argsize: %d",
1098
    frame_method->name_and_sig_as_C_string(), _freeze_size, fsize, argsize);
1099
  // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1100
  assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1101

1102
  freeze_result result = recurse_freeze_java_frame<ContinuationHelper::InterpretedFrame>(f, caller, fsize, argsize);
1103
  if (UNLIKELY(result > freeze_ok_bottom)) {
1104
    return result;
1105
  }
1106

1107
  bool is_bottom_frame = result == freeze_ok_bottom;
1108
  assert(!caller.is_empty() || is_bottom_frame, "");
1109

1110
  DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, is_bottom_frame);)
1111

1112
  frame hf = new_heap_frame<ContinuationHelper::InterpretedFrame>(f, caller);
1113
  _total_align_size += frame::align_wiggle; // add alignment room for internal interpreted frame alignment on AArch64/PPC64
1114

1115
  intptr_t* heap_frame_top = ContinuationHelper::InterpretedFrame::frame_top(hf, callee_argsize, callee_interpreted);
1116
  intptr_t* heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
1117
  assert(heap_frame_bottom == heap_frame_top + fsize, "");
1118

1119
  // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
1120
  // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
1121
  copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1122
  assert(!is_bottom_frame || !caller.is_interpreted_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1123

1124
  relativize_interpreted_frame_metadata(f, hf);
1125

1126
  patch(f, hf, caller, is_bottom_frame);
1127

1128
  CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
1129
  DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1130
  caller = hf;
1131

1132
  // Mark frame_method's GC epoch for class redefinition on_stack calculation.
1133
  frame_method->record_gc_epoch();
1134

1135
  return freeze_ok;
1136
}
1137

1138
// The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1139
// See also StackChunkFrameStream<frame_kind>::frame_size()
1140
freeze_result FreezeBase::recurse_freeze_compiled_frame(frame& f, frame& caller,
1141
                                                        int callee_argsize /* incl. metadata */,
1142
                                                        bool callee_interpreted) {
1143
  // The frame's top never includes the stack arguments to the callee
1144
  intptr_t* const stack_frame_top = ContinuationHelper::CompiledFrame::frame_top(f, callee_argsize, callee_interpreted);
1145
  intptr_t* const stack_frame_bottom = ContinuationHelper::CompiledFrame::frame_bottom(f);
1146
  // including metadata between f and its stackargs
1147
  const int argsize = ContinuationHelper::CompiledFrame::stack_argsize(f) + frame::metadata_words_at_top;
1148
  const int fsize = pointer_delta_as_int(stack_frame_bottom + argsize, stack_frame_top);
1149

1150
  log_develop_trace(continuations)("recurse_freeze_compiled_frame %s _size: %d fsize: %d argsize: %d",
1151
                             ContinuationHelper::Frame::frame_method(f) != nullptr ?
1152
                             ContinuationHelper::Frame::frame_method(f)->name_and_sig_as_C_string() : "",
1153
                             _freeze_size, fsize, argsize);
1154
  // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1155
  assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1156

1157
  freeze_result result = recurse_freeze_java_frame<ContinuationHelper::CompiledFrame>(f, caller, fsize, argsize);
1158
  if (UNLIKELY(result > freeze_ok_bottom)) {
1159
    return result;
1160
  }
1161

1162
  bool is_bottom_frame = result == freeze_ok_bottom;
1163
  assert(!caller.is_empty() || is_bottom_frame, "");
1164

1165
  DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, is_bottom_frame);)
1166

1167
  frame hf = new_heap_frame<ContinuationHelper::CompiledFrame>(f, caller);
1168

1169
  intptr_t* heap_frame_top = ContinuationHelper::CompiledFrame::frame_top(hf, callee_argsize, callee_interpreted);
1170

1171
  copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1172
  assert(!is_bottom_frame || !caller.is_compiled_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1173

1174
  if (caller.is_interpreted_frame()) {
1175
    _total_align_size += frame::align_wiggle; // See Thaw::align
1176
  }
1177

1178
  patch(f, hf, caller, is_bottom_frame);
1179

1180
  assert(is_bottom_frame || Interpreter::contains(ContinuationHelper::CompiledFrame::real_pc(caller)) == caller.is_interpreted_frame(), "");
1181

1182
  DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1183
  caller = hf;
1184
  return freeze_ok;
1185
}
1186

1187
NOINLINE freeze_result FreezeBase::recurse_freeze_stub_frame(frame& f, frame& caller) {
1188
  intptr_t* const stack_frame_top = ContinuationHelper::StubFrame::frame_top(f, 0, 0);
1189
  const int fsize = f.cb()->frame_size();
1190

1191
  log_develop_trace(continuations)("recurse_freeze_stub_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1192
    f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1193

1194
  // recurse_freeze_java_frame and freeze inlined here because we need to use a full RegisterMap for lock ownership
1195
  NOT_PRODUCT(_frames++;)
1196
  _freeze_size += fsize;
1197

1198
  RegisterMap map(_cont.thread(),
1199
                  RegisterMap::UpdateMap::include,
1200
                  RegisterMap::ProcessFrames::skip,
1201
                  RegisterMap::WalkContinuation::skip);
1202
  map.set_include_argument_oops(false);
1203
  ContinuationHelper::update_register_map<ContinuationHelper::StubFrame>(f, &map);
1204
  f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1205
  frame senderf = sender<ContinuationHelper::StubFrame>(f);
1206
  assert(senderf.unextended_sp() < _bottom_address - 1, "");
1207
  assert(senderf.is_compiled_frame(), "");
1208

1209
  if (UNLIKELY(senderf.oop_map() == nullptr)) {
1210
    // native frame
1211
    return freeze_pinned_native;
1212
  }
1213

1214
  freeze_result result = recurse_freeze_compiled_frame(senderf, caller, 0, 0); // This might be deoptimized
1215
  if (UNLIKELY(result > freeze_ok_bottom)) {
1216
    return result;
1217
  }
1218
  assert(result != freeze_ok_bottom, "");
1219
  assert(!caller.is_interpreted_frame(), "");
1220

1221
  DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, false);)
1222
  frame hf = new_heap_frame<ContinuationHelper::StubFrame>(f, caller);
1223
  intptr_t* heap_frame_top = ContinuationHelper::StubFrame::frame_top(hf, 0, 0);
1224
  copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1225
  DEBUG_ONLY(after_freeze_java_frame(hf, false);)
1226

1227
  caller = hf;
1228
  return freeze_ok;
1229
}
1230

1231
NOINLINE void FreezeBase::finish_freeze(const frame& f, const frame& top) {
1232
  stackChunkOop chunk = _cont.tail();
1233

1234
  LogTarget(Trace, continuations) lt;
1235
  if (lt.develop_is_enabled()) {
1236
    LogStream ls(lt);
1237
    assert(top.is_heap_frame(), "should be");
1238
    top.print_on(&ls);
1239
  }
1240

1241
  set_top_frame_metadata_pd(top);
1242

1243
  chunk->set_sp(chunk->to_offset(top.sp()));
1244
  chunk->set_pc(top.pc());
1245

1246
  chunk->set_max_thawing_size(chunk->max_thawing_size() + _total_align_size);
1247

1248
  // At this point the chunk is consistent
1249

1250
  if (UNLIKELY(_barriers)) {
1251
    log_develop_trace(continuations)("do barriers on old chunk");
1252
    // Serial and Parallel GC can allocate objects directly into the old generation.
1253
    // Then we want to relativize the derived pointers eagerly so that
1254
    // old chunks are all in GC mode.
1255
    assert(!UseG1GC, "G1 can not deal with allocating outside of eden");
1256
    assert(!UseZGC, "ZGC can not deal with allocating chunks visible to marking");
1257
    if (UseShenandoahGC) {
1258
      _cont.tail()->relativize_derived_pointers_concurrently();
1259
    } else {
1260
      ContinuationGCSupport::transform_stack_chunk(_cont.tail());
1261
    }
1262
    // For objects in the old generation we must maintain the remembered set
1263
    _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>();
1264
  }
1265

1266
  log_develop_trace(continuations)("finish_freeze: has_mixed_frames: %d", chunk->has_mixed_frames());
1267
  if (lt.develop_is_enabled()) {
1268
    LogStream ls(lt);
1269
    chunk->print_on(true, &ls);
1270
  }
1271

1272
  if (lt.develop_is_enabled()) {
1273
    LogStream ls(lt);
1274
    ls.print_cr("top hframe after (freeze):");
1275
    assert(_cont.last_frame().is_heap_frame(), "should be");
1276
    _cont.last_frame().print_on(&ls);
1277
  }
1278

1279
  assert(_cont.chunk_invariant(), "");
1280
}
1281

1282
inline bool FreezeBase::stack_overflow() { // detect stack overflow in recursive native code
1283
  JavaThread* t = !_preempt ? _thread : JavaThread::current();
1284
  assert(t == JavaThread::current(), "");
1285
  if (os::current_stack_pointer() < t->stack_overflow_state()->shadow_zone_safe_limit()) {
1286
    if (!_preempt) {
1287
      ContinuationWrapper::SafepointOp so(t, _cont); // could also call _cont.done() instead
1288
      Exceptions::_throw_msg(t, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Stack overflow while freezing");
1289
    }
1290
    return true;
1291
  }
1292
  return false;
1293
}
1294

1295
class StackChunkAllocator : public MemAllocator {
1296
  const size_t                                 _stack_size;
1297
  int                                          _argsize_md;
1298
  ContinuationWrapper&                         _continuation_wrapper;
1299
  JvmtiSampledObjectAllocEventCollector* const _jvmti_event_collector;
1300
  mutable bool                                 _took_slow_path;
1301

1302
  // Does the minimal amount of initialization needed for a TLAB allocation.
1303
  // We don't need to do a full initialization, as such an allocation need not be immediately walkable.
1304
  virtual oop initialize(HeapWord* mem) const override {
1305
    assert(_stack_size > 0, "");
1306
    assert(_stack_size <= max_jint, "");
1307
    assert(_word_size > _stack_size, "");
1308

1309
    // zero out fields (but not the stack)
1310
    const size_t hs = oopDesc::header_size();
1311
    Copy::fill_to_aligned_words(mem + hs, vmClasses::StackChunk_klass()->size_helper() - hs);
1312

1313
    int bottom = (int)_stack_size - _argsize_md;
1314

1315
    jdk_internal_vm_StackChunk::set_size(mem, (int)_stack_size);
1316
    jdk_internal_vm_StackChunk::set_bottom(mem, bottom);
1317
    jdk_internal_vm_StackChunk::set_sp(mem, bottom);
1318

1319
    return finish(mem);
1320
  }
1321

1322
  stackChunkOop allocate_fast() const {
1323
    if (!UseTLAB) {
1324
      return nullptr;
1325
    }
1326

1327
    HeapWord* const mem = MemAllocator::mem_allocate_inside_tlab_fast();
1328
    if (mem == nullptr) {
1329
      return nullptr;
1330
    }
1331

1332
    oop obj = initialize(mem);
1333
    return stackChunkOopDesc::cast(obj);
1334
  }
1335

1336
public:
1337
  StackChunkAllocator(Klass* klass,
1338
                      size_t word_size,
1339
                      Thread* thread,
1340
                      size_t stack_size,
1341
                      int argsize_md,
1342
                      ContinuationWrapper& continuation_wrapper,
1343
                      JvmtiSampledObjectAllocEventCollector* jvmti_event_collector)
1344
    : MemAllocator(klass, word_size, thread),
1345
      _stack_size(stack_size),
1346
      _argsize_md(argsize_md),
1347
      _continuation_wrapper(continuation_wrapper),
1348
      _jvmti_event_collector(jvmti_event_collector),
1349
      _took_slow_path(false) {}
1350

1351
  // Provides it's own, specialized allocation which skips instrumentation
1352
  // if the memory can be allocated without going to a slow-path.
1353
  stackChunkOop allocate() const {
1354
    // First try to allocate without any slow-paths or instrumentation.
1355
    stackChunkOop obj = allocate_fast();
1356
    if (obj != nullptr) {
1357
      return obj;
1358
    }
1359

1360
    // Now try full-blown allocation with all expensive operations,
1361
    // including potentially safepoint operations.
1362
    _took_slow_path = true;
1363

1364
    // Protect unhandled Loom oops
1365
    ContinuationWrapper::SafepointOp so(_thread, _continuation_wrapper);
1366

1367
    // Can safepoint
1368
    _jvmti_event_collector->start();
1369

1370
    // Can safepoint
1371
    return stackChunkOopDesc::cast(MemAllocator::allocate());
1372
  }
1373

1374
  bool took_slow_path() const {
1375
    return _took_slow_path;
1376
  }
1377
};
1378

1379
template <typename ConfigT>
1380
stackChunkOop Freeze<ConfigT>::allocate_chunk(size_t stack_size, int argsize_md) {
1381
  log_develop_trace(continuations)("allocate_chunk allocating new chunk");
1382

1383
  InstanceStackChunkKlass* klass = InstanceStackChunkKlass::cast(vmClasses::StackChunk_klass());
1384
  size_t size_in_words = klass->instance_size(stack_size);
1385

1386
  if (CollectedHeap::stack_chunk_max_size() > 0 && size_in_words >= CollectedHeap::stack_chunk_max_size()) {
1387
    if (!_preempt) {
1388
      throw_stack_overflow_on_humongous_chunk();
1389
    }
1390
    return nullptr;
1391
  }
1392

1393
  JavaThread* current = _preempt ? JavaThread::current() : _thread;
1394
  assert(current == JavaThread::current(), "should be current");
1395

1396
  // Allocate the chunk.
1397
  //
1398
  // This might safepoint while allocating, but all safepointing due to
1399
  // instrumentation have been deferred. This property is important for
1400
  // some GCs, as this ensures that the allocated object is in the young
1401
  // generation / newly allocated memory.
1402
  StackChunkAllocator allocator(klass, size_in_words, current, stack_size, argsize_md, _cont, _jvmti_event_collector);
1403
  stackChunkOop chunk = allocator.allocate();
1404

1405
  if (chunk == nullptr) {
1406
    return nullptr; // OOME
1407
  }
1408

1409
  // assert that chunk is properly initialized
1410
  assert(chunk->stack_size() == (int)stack_size, "");
1411
  assert(chunk->size() >= stack_size, "chunk->size(): %zu size: %zu", chunk->size(), stack_size);
1412
  assert(chunk->sp() == chunk->bottom(), "");
1413
  assert((intptr_t)chunk->start_address() % 8 == 0, "");
1414
  assert(chunk->max_thawing_size() == 0, "");
1415
  assert(chunk->pc() == nullptr, "");
1416
  assert(chunk->is_empty(), "");
1417
  assert(chunk->flags() == 0, "");
1418
  assert(chunk->is_gc_mode() == false, "");
1419

1420
  // fields are uninitialized
1421
  chunk->set_parent_access<IS_DEST_UNINITIALIZED>(_cont.last_nonempty_chunk());
1422
  chunk->set_cont_access<IS_DEST_UNINITIALIZED>(_cont.continuation());
1423

1424
#if INCLUDE_ZGC
1425
  if (UseZGC) {
1426
    if (ZGenerational) {
1427
      ZStackChunkGCData::initialize(chunk);
1428
    }
1429
    assert(!chunk->requires_barriers(), "ZGC always allocates in the young generation");
1430
    _barriers = false;
1431
  } else
1432
#endif
1433
#if INCLUDE_SHENANDOAHGC
1434
  if (UseShenandoahGC) {
1435
    _barriers = chunk->requires_barriers();
1436
  } else
1437
#endif
1438
  {
1439
    if (!allocator.took_slow_path()) {
1440
      // Guaranteed to be in young gen / newly allocated memory
1441
      assert(!chunk->requires_barriers(), "Unfamiliar GC requires barriers on TLAB allocation");
1442
      _barriers = false;
1443
    } else {
1444
      // Some GCs could put direct allocations in old gen for slow-path
1445
      // allocations; need to explicitly check if that was the case.
1446
      _barriers = chunk->requires_barriers();
1447
    }
1448
  }
1449

1450
  if (_barriers) {
1451
    log_develop_trace(continuations)("allocation requires barriers");
1452
  }
1453

1454
  assert(chunk->parent() == nullptr || chunk->parent()->is_stackChunk(), "");
1455

1456
  return chunk;
1457
}
1458

1459
void FreezeBase::throw_stack_overflow_on_humongous_chunk() {
1460
  ContinuationWrapper::SafepointOp so(_thread, _cont); // could also call _cont.done() instead
1461
  Exceptions::_throw_msg(_thread, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Humongous stack chunk");
1462
}
1463

1464
#if INCLUDE_JVMTI
1465
static int num_java_frames(ContinuationWrapper& cont) {
1466
  ResourceMark rm; // used for scope traversal in num_java_frames(nmethod*, address)
1467
  int count = 0;
1468
  for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
1469
    count += chunk->num_java_frames();
1470
  }
1471
  return count;
1472
}
1473

1474
static void invalidate_jvmti_stack(JavaThread* thread) {
1475
  if (thread->is_interp_only_mode()) {
1476
    JvmtiThreadState *state = thread->jvmti_thread_state();
1477
    if (state != nullptr)
1478
      state->invalidate_cur_stack_depth();
1479
  }
1480
}
1481

1482
static void jvmti_yield_cleanup(JavaThread* thread, ContinuationWrapper& cont) {
1483
  if (JvmtiExport::can_post_frame_pop()) {
1484
    int num_frames = num_java_frames(cont);
1485

1486
    ContinuationWrapper::SafepointOp so(Thread::current(), cont);
1487
    JvmtiExport::continuation_yield_cleanup(JavaThread::current(), num_frames);
1488
  }
1489
  invalidate_jvmti_stack(thread);
1490
}
1491
#endif // INCLUDE_JVMTI
1492

1493
#ifdef ASSERT
1494
static bool monitors_on_stack(JavaThread* thread) {
1495
  ContinuationEntry* ce = thread->last_continuation();
1496
  RegisterMap map(thread,
1497
                  RegisterMap::UpdateMap::include,
1498
                  RegisterMap::ProcessFrames::include,
1499
                  RegisterMap::WalkContinuation::skip);
1500
  map.set_include_argument_oops(false);
1501
  for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
1502
    if ((f.is_interpreted_frame() && ContinuationHelper::InterpretedFrame::is_owning_locks(f)) ||
1503
        (f.is_compiled_frame() && ContinuationHelper::CompiledFrame::is_owning_locks(map.thread(), &map, f))) {
1504
      return true;
1505
    }
1506
  }
1507
  return false;
1508
}
1509

1510
// There are no interpreted frames if we're not called from the interpreter and we haven't ancountered an i2c
1511
// adapter or called Deoptimization::unpack_frames. As for native frames, upcalls from JNI also go through the
1512
// interpreter (see JavaCalls::call_helper), while the UpcallLinker explicitly sets cont_fastpath.
1513
bool FreezeBase::check_valid_fast_path() {
1514
  ContinuationEntry* ce = _thread->last_continuation();
1515
  RegisterMap map(_thread,
1516
                  RegisterMap::UpdateMap::skip,
1517
                  RegisterMap::ProcessFrames::skip,
1518
                  RegisterMap::WalkContinuation::skip);
1519
  map.set_include_argument_oops(false);
1520
  for (frame f = freeze_start_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
1521
    if (!f.is_compiled_frame() || f.is_deoptimized_frame()) {
1522
      return false;
1523
    }
1524
  }
1525
  return true;
1526
}
1527
#endif // ASSERT
1528

1529
static inline int freeze_epilog(JavaThread* thread, ContinuationWrapper& cont) {
1530
  verify_continuation(cont.continuation());
1531
  assert(!cont.is_empty(), "");
1532
  // This is done for the sake of the enterSpecial frame
1533
  StackWatermarkSet::after_unwind(thread);
1534

1535
  log_develop_debug(continuations)("=== End of freeze cont ### #" INTPTR_FORMAT, cont.hash());
1536

1537
  return 0;
1538
}
1539

1540
static int freeze_epilog(JavaThread* thread, ContinuationWrapper& cont, freeze_result res) {
1541
  if (UNLIKELY(res != freeze_ok)) {
1542
    verify_continuation(cont.continuation());
1543
    log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1544
    return res;
1545
  }
1546

1547
  JVMTI_ONLY(jvmti_yield_cleanup(thread, cont)); // can safepoint
1548
  return freeze_epilog(thread, cont);
1549
}
1550

1551
template<typename ConfigT>
1552
static inline int freeze_internal(JavaThread* current, intptr_t* const sp) {
1553
  assert(!current->has_pending_exception(), "");
1554

1555
#ifdef ASSERT
1556
  log_trace(continuations)("~~~~ freeze sp: " INTPTR_FORMAT, p2i(current->last_continuation()->entry_sp()));
1557
  log_frames(current);
1558
#endif
1559

1560
  CONT_JFR_ONLY(EventContinuationFreeze event;)
1561

1562
  ContinuationEntry* entry = current->last_continuation();
1563

1564
  oop oopCont = entry->cont_oop(current);
1565
  assert(oopCont == current->last_continuation()->cont_oop(current), "");
1566
  assert(ContinuationEntry::assert_entry_frame_laid_out(current), "");
1567

1568
  verify_continuation(oopCont);
1569
  ContinuationWrapper cont(current, oopCont);
1570
  log_develop_debug(continuations)("FREEZE #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
1571

1572
  assert(entry->is_virtual_thread() == (entry->scope(current) == java_lang_VirtualThread::vthread_scope()), "");
1573

1574
  assert(monitors_on_stack(current) == ((current->held_monitor_count() - current->jni_monitor_count()) > 0),
1575
         "Held monitor count and locks on stack invariant: " INT64_FORMAT " JNI: " INT64_FORMAT, (int64_t)current->held_monitor_count(), (int64_t)current->jni_monitor_count());
1576

1577
  if (entry->is_pinned() || current->held_monitor_count() > 0) {
1578
    log_develop_debug(continuations)("PINNED due to critical section/hold monitor");
1579
    verify_continuation(cont.continuation());
1580
    freeze_result res = entry->is_pinned() ? freeze_pinned_cs : freeze_pinned_monitor;
1581
    log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1582
    // Avoid Thread.yield() loops without safepoint polls.
1583
    if (SafepointMechanism::should_process(current)) {
1584
      cont.done(); // allow safepoint
1585
      ThreadInVMfromJava tivmfj(current);
1586
    }
1587
    return res;
1588
  }
1589

1590
  Freeze<ConfigT> freeze(current, cont, sp);
1591

1592
  assert(!current->cont_fastpath() || freeze.check_valid_fast_path(), "");
1593
  bool fast = UseContinuationFastPath && current->cont_fastpath();
1594
  if (fast && freeze.size_if_fast_freeze_available() > 0) {
1595
    freeze.freeze_fast_existing_chunk();
1596
    CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1597
    freeze_epilog(current, cont);
1598
    return 0;
1599
  }
1600

1601
  log_develop_trace(continuations)("chunk unavailable; transitioning to VM");
1602
  assert(current == JavaThread::current(), "must be current thread except for preempt");
1603
  JRT_BLOCK
1604
    // delays a possible JvmtiSampledObjectAllocEventCollector in alloc_chunk
1605
    JvmtiSampledObjectAllocEventCollector jsoaec(false);
1606
    freeze.set_jvmti_event_collector(&jsoaec);
1607

1608
    freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1609

1610
    CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1611
    freeze_epilog(current, cont, res);
1612
    cont.done(); // allow safepoint in the transition back to Java
1613
    return res;
1614
  JRT_BLOCK_END
1615
}
1616

1617
static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint) {
1618
  ContinuationEntry* entry = thread->last_continuation();
1619
  if (entry == nullptr) {
1620
    return freeze_ok;
1621
  }
1622
  if (entry->is_pinned()) {
1623
    return freeze_pinned_cs;
1624
  } else if (thread->held_monitor_count() > 0) {
1625
    return freeze_pinned_monitor;
1626
  }
1627

1628
  RegisterMap map(thread,
1629
                  RegisterMap::UpdateMap::include,
1630
                  RegisterMap::ProcessFrames::skip,
1631
                  RegisterMap::WalkContinuation::skip);
1632
  map.set_include_argument_oops(false);
1633
  frame f = thread->last_frame();
1634

1635
  if (!safepoint) {
1636
    f = f.sender(&map); // this is the yield frame
1637
  } else { // safepoint yield
1638
#if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
1639
    f.set_fp(f.real_fp()); // Instead of this, maybe in ContinuationWrapper::set_last_frame always use the real_fp?
1640
#else
1641
    Unimplemented();
1642
#endif
1643
    if (!Interpreter::contains(f.pc())) {
1644
      assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
1645
      assert(f.oop_map() != nullptr, "must be");
1646
      f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1647
    }
1648
  }
1649

1650
  while (true) {
1651
    if ((f.is_interpreted_frame() && f.interpreter_frame_method()->is_native()) || f.is_native_frame()) {
1652
      return freeze_pinned_native;
1653
    }
1654

1655
    f = f.sender(&map);
1656
    if (!Continuation::is_frame_in_continuation(entry, f)) {
1657
      oop scope = jdk_internal_vm_Continuation::scope(entry->cont_oop(thread));
1658
      if (scope == cont_scope) {
1659
        break;
1660
      }
1661
      intx monitor_count = entry->parent_held_monitor_count();
1662
      entry = entry->parent();
1663
      if (entry == nullptr) {
1664
        break;
1665
      }
1666
      if (entry->is_pinned()) {
1667
        return freeze_pinned_cs;
1668
      } else if (monitor_count > 0) {
1669
        return freeze_pinned_monitor;
1670
      }
1671
    }
1672
  }
1673
  return freeze_ok;
1674
}
1675

1676
/////////////// THAW ////
1677

1678
static int thaw_size(stackChunkOop chunk) {
1679
  int size = chunk->max_thawing_size();
1680
  size += frame::metadata_words; // For the top pc+fp in push_return_frame or top = stack_sp - frame::metadata_words in thaw_fast
1681
  size += 2*frame::align_wiggle; // in case of alignments at the top and bottom
1682
  return size;
1683
}
1684

1685
// make room on the stack for thaw
1686
// returns the size in bytes, or 0 on failure
1687
static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier) {
1688
  log_develop_trace(continuations)("~~~~ prepare_thaw return_barrier: %d", return_barrier);
1689

1690
  assert(thread == JavaThread::current(), "");
1691

1692
  ContinuationEntry* ce = thread->last_continuation();
1693
  assert(ce != nullptr, "");
1694
  oop continuation = ce->cont_oop(thread);
1695
  assert(continuation == get_continuation(thread), "");
1696
  verify_continuation(continuation);
1697

1698
  stackChunkOop chunk = jdk_internal_vm_Continuation::tail(continuation);
1699
  assert(chunk != nullptr, "");
1700

1701
  // The tail can be empty because it might still be available for another freeze.
1702
  // However, here we want to thaw, so we get rid of it (it will be GCed).
1703
  if (UNLIKELY(chunk->is_empty())) {
1704
    chunk = chunk->parent();
1705
    assert(chunk != nullptr, "");
1706
    assert(!chunk->is_empty(), "");
1707
    jdk_internal_vm_Continuation::set_tail(continuation, chunk);
1708
  }
1709

1710
  // Verification
1711
  chunk->verify();
1712
  assert(chunk->max_thawing_size() > 0, "chunk invariant violated; expected to not be empty");
1713

1714
  // Only make space for the last chunk because we only thaw from the last chunk
1715
  int size = thaw_size(chunk) << LogBytesPerWord;
1716

1717
  const address bottom = (address)thread->last_continuation()->entry_sp();
1718
  // 300 is an estimate for stack size taken for this native code, in addition to StackShadowPages
1719
  // for the Java frames in the check below.
1720
  if (!stack_overflow_check(thread, size + 300, bottom)) {
1721
    return 0;
1722
  }
1723

1724
  log_develop_trace(continuations)("prepare_thaw bottom: " INTPTR_FORMAT " top: " INTPTR_FORMAT " size: %d",
1725
                              p2i(bottom), p2i(bottom - size), size);
1726
  return size;
1727
}
1728

1729
class ThawBase : public StackObj {
1730
protected:
1731
  JavaThread* _thread;
1732
  ContinuationWrapper& _cont;
1733
  CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
1734

1735
  intptr_t* _fastpath;
1736
  bool _barriers;
1737
  intptr_t* _top_unextended_sp_before_thaw;
1738
  int _align_size;
1739
  DEBUG_ONLY(intptr_t* _top_stack_address);
1740

1741
  StackChunkFrameStream<ChunkFrames::Mixed> _stream;
1742

1743
  NOT_PRODUCT(int _frames;)
1744

1745
protected:
1746
  ThawBase(JavaThread* thread, ContinuationWrapper& cont) :
1747
      _thread(thread), _cont(cont),
1748
      _fastpath(nullptr) {
1749
    DEBUG_ONLY(_top_unextended_sp_before_thaw = nullptr;)
1750
    assert (cont.tail() != nullptr, "no last chunk");
1751
    DEBUG_ONLY(_top_stack_address = _cont.entrySP() - thaw_size(cont.tail());)
1752
  }
1753

1754
  void clear_chunk(stackChunkOop chunk);
1755
  int remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize);
1756
  void copy_from_chunk(intptr_t* from, intptr_t* to, int size);
1757

1758
  // fast path
1759
  inline void prefetch_chunk_pd(void* start, int size_words);
1760
  void patch_return(intptr_t* sp, bool is_last);
1761

1762
  // slow path
1763
  NOINLINE intptr_t* thaw_slow(stackChunkOop chunk, bool return_barrier);
1764

1765
private:
1766
  void recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top);
1767
  template<typename FKind> bool recurse_thaw_java_frame(frame& caller, int num_frames);
1768
  void finalize_thaw(frame& entry, int argsize);
1769

1770
  inline bool seen_by_gc();
1771

1772
  inline void before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame);
1773
  inline void after_thaw_java_frame(const frame& f, bool bottom);
1774
  inline void patch(frame& f, const frame& caller, bool bottom);
1775
  void clear_bitmap_bits(address start, address end);
1776

1777
  NOINLINE void recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames);
1778
  void recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller);
1779
  void recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames);
1780
  void finish_thaw(frame& f);
1781

1782
  void push_return_frame(frame& f);
1783
  inline frame new_entry_frame();
1784
  template<typename FKind> frame new_stack_frame(const frame& hf, frame& caller, bool bottom);
1785
  inline void patch_pd(frame& f, const frame& sender);
1786
  inline intptr_t* align(const frame& hf, intptr_t* frame_sp, frame& caller, bool bottom);
1787

1788
  void maybe_set_fastpath(intptr_t* sp) { if (sp > _fastpath) _fastpath = sp; }
1789

1790
  static inline void derelativize_interpreted_frame_metadata(const frame& hf, const frame& f);
1791

1792
 public:
1793
  CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
1794
};
1795

1796
template <typename ConfigT>
1797
class Thaw : public ThawBase {
1798
public:
1799
  Thaw(JavaThread* thread, ContinuationWrapper& cont) : ThawBase(thread, cont) {}
1800

1801
  inline bool can_thaw_fast(stackChunkOop chunk) {
1802
    return    !_barriers
1803
           &&  _thread->cont_fastpath_thread_state()
1804
           && !chunk->has_thaw_slowpath_condition()
1805
           && !PreserveFramePointer;
1806
  }
1807

1808
  inline intptr_t* thaw(Continuation::thaw_kind kind);
1809
  NOINLINE intptr_t* thaw_fast(stackChunkOop chunk);
1810
  inline void patch_caller_links(intptr_t* sp, intptr_t* bottom);
1811
};
1812

1813
template <typename ConfigT>
1814
inline intptr_t* Thaw<ConfigT>::thaw(Continuation::thaw_kind kind) {
1815
  verify_continuation(_cont.continuation());
1816
  assert(!jdk_internal_vm_Continuation::done(_cont.continuation()), "");
1817
  assert(!_cont.is_empty(), "");
1818

1819
  stackChunkOop chunk = _cont.tail();
1820
  assert(chunk != nullptr, "guaranteed by prepare_thaw");
1821
  assert(!chunk->is_empty(), "guaranteed by prepare_thaw");
1822

1823
  _barriers = chunk->requires_barriers();
1824
  return (LIKELY(can_thaw_fast(chunk))) ? thaw_fast(chunk)
1825
                                        : thaw_slow(chunk, kind != Continuation::thaw_top);
1826
}
1827

1828
class ReconstructedStack : public StackObj {
1829
  intptr_t* _base;  // _cont.entrySP(); // top of the entry frame
1830
  int _thaw_size;
1831
  int _argsize;
1832
public:
1833
  ReconstructedStack(intptr_t* base, int thaw_size, int argsize)
1834
  : _base(base), _thaw_size(thaw_size - (argsize == 0 ? frame::metadata_words_at_top : 0)), _argsize(argsize) {
1835
    // The only possible source of misalignment is stack-passed arguments b/c compiled frames are 16-byte aligned.
1836
    assert(argsize != 0 || (_base - _thaw_size) == ContinuationHelper::frame_align_pointer(_base - _thaw_size), "");
1837
    // We're at most one alignment word away from entrySP
1838
    assert(_base - 1 <= top() + total_size() + frame::metadata_words_at_bottom, "missed entry frame");
1839
  }
1840

1841
  int entry_frame_extension() const { return _argsize + (_argsize > 0 ? frame::metadata_words_at_top : 0); }
1842

1843
  // top and bottom stack pointers
1844
  intptr_t* sp() const { return ContinuationHelper::frame_align_pointer(_base - _thaw_size); }
1845
  intptr_t* bottom_sp() const { return ContinuationHelper::frame_align_pointer(_base - entry_frame_extension()); }
1846

1847
  // several operations operate on the totality of the stack being reconstructed,
1848
  // including the metadata words
1849
  intptr_t* top() const { return sp() - frame::metadata_words_at_bottom;  }
1850
  int total_size() const { return _thaw_size + frame::metadata_words_at_bottom; }
1851
};
1852

1853
inline void ThawBase::clear_chunk(stackChunkOop chunk) {
1854
  chunk->set_sp(chunk->bottom());
1855
  chunk->set_max_thawing_size(0);
1856
}
1857

1858
int ThawBase::remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize) {
1859
  bool empty = false;
1860
  StackChunkFrameStream<ChunkFrames::CompiledOnly> f(chunk);
1861
  DEBUG_ONLY(intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();)
1862
  assert(chunk_sp == f.sp(), "");
1863
  assert(chunk_sp == f.unextended_sp(), "");
1864

1865
  const int frame_size = f.cb()->frame_size();
1866
  argsize = f.stack_argsize();
1867

1868
  f.next(SmallRegisterMap::instance, true /* stop */);
1869
  empty = f.is_done();
1870
  assert(!empty || argsize == chunk->argsize(), "");
1871

1872
  if (empty) {
1873
    clear_chunk(chunk);
1874
  } else {
1875
    chunk->set_sp(chunk->sp() + frame_size);
1876
    chunk->set_max_thawing_size(chunk->max_thawing_size() - frame_size);
1877
    // We set chunk->pc to the return pc into the next frame
1878
    chunk->set_pc(f.pc());
1879
#ifdef ASSERT
1880
    {
1881
      intptr_t* retaddr_slot = (chunk_sp
1882
                                + frame_size
1883
                                - frame::sender_sp_ret_address_offset());
1884
      assert(f.pc() == ContinuationHelper::return_address_at(retaddr_slot),
1885
             "unexpected pc");
1886
    }
1887
#endif
1888
  }
1889
  assert(empty == chunk->is_empty(), "");
1890
  // returns the size required to store the frame on stack, and because it is a
1891
  // compiled frame, it must include a copy of the arguments passed by the caller
1892
  return frame_size + argsize + frame::metadata_words_at_top;
1893
}
1894

1895
void ThawBase::copy_from_chunk(intptr_t* from, intptr_t* to, int size) {
1896
  assert(to >= _top_stack_address, "overwrote past thawing space"
1897
    " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(to), p2i(_top_stack_address));
1898
  assert(to + size <= _cont.entrySP(), "overwrote past thawing space");
1899
  _cont.tail()->copy_from_chunk_to_stack(from, to, size);
1900
  CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
1901
}
1902

1903
void ThawBase::patch_return(intptr_t* sp, bool is_last) {
1904
  log_develop_trace(continuations)("thaw_fast patching -- sp: " INTPTR_FORMAT, p2i(sp));
1905

1906
  address pc = !is_last ? StubRoutines::cont_returnBarrier() : _cont.entryPC();
1907
  ContinuationHelper::patch_return_address_at(
1908
    sp - frame::sender_sp_ret_address_offset(),
1909
    pc);
1910
}
1911

1912
template <typename ConfigT>
1913
NOINLINE intptr_t* Thaw<ConfigT>::thaw_fast(stackChunkOop chunk) {
1914
  assert(chunk == _cont.tail(), "");
1915
  assert(!chunk->has_mixed_frames(), "");
1916
  assert(!chunk->requires_barriers(), "");
1917
  assert(!chunk->has_bitmap(), "");
1918
  assert(!_thread->is_interp_only_mode(), "");
1919

1920
  LogTarget(Trace, continuations) lt;
1921
  if (lt.develop_is_enabled()) {
1922
    LogStream ls(lt);
1923
    ls.print_cr("thaw_fast");
1924
    chunk->print_on(true, &ls);
1925
  }
1926

1927
  // Below this heuristic, we thaw the whole chunk, above it we thaw just one frame.
1928
  static const int threshold = 500; // words
1929

1930
  const int full_chunk_size = chunk->stack_size() - chunk->sp(); // this initial size could be reduced if it's a partial thaw
1931
  int argsize, thaw_size;
1932

1933
  intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();
1934

1935
  bool partial, empty;
1936
  if (LIKELY(!TEST_THAW_ONE_CHUNK_FRAME && (full_chunk_size < threshold))) {
1937
    prefetch_chunk_pd(chunk->start_address(), full_chunk_size); // prefetch anticipating memcpy starting at highest address
1938

1939
    partial = false;
1940
    argsize = chunk->argsize(); // must be called *before* clearing the chunk
1941
    clear_chunk(chunk);
1942
    thaw_size = full_chunk_size;
1943
    empty = true;
1944
  } else { // thaw a single frame
1945
    partial = true;
1946
    thaw_size = remove_top_compiled_frame_from_chunk(chunk, argsize);
1947
    empty = chunk->is_empty();
1948
  }
1949

1950
  // Are we thawing the last frame(s) in the continuation
1951
  const bool is_last = empty && chunk->parent() == nullptr;
1952
  assert(!is_last || argsize == 0, "");
1953

1954
  log_develop_trace(continuations)("thaw_fast partial: %d is_last: %d empty: %d size: %d argsize: %d entrySP: " PTR_FORMAT,
1955
                              partial, is_last, empty, thaw_size, argsize, p2i(_cont.entrySP()));
1956

1957
  ReconstructedStack rs(_cont.entrySP(), thaw_size, argsize);
1958

1959
  // also copy metadata words at frame bottom
1960
  copy_from_chunk(chunk_sp - frame::metadata_words_at_bottom, rs.top(), rs.total_size());
1961

1962
  // update the ContinuationEntry
1963
  _cont.set_argsize(argsize);
1964
  log_develop_trace(continuations)("setting entry argsize: %d", _cont.argsize());
1965
  assert(rs.bottom_sp() == _cont.entry()->bottom_sender_sp(), "");
1966

1967
  // install the return barrier if not last frame, or the entry's pc if last
1968
  patch_return(rs.bottom_sp(), is_last);
1969

1970
  // insert the back links from callee to caller frames
1971
  patch_caller_links(rs.top(), rs.top() + rs.total_size());
1972

1973
  assert(is_last == _cont.is_empty(), "");
1974
  assert(_cont.chunk_invariant(), "");
1975

1976
#if CONT_JFR
1977
  EventContinuationThawFast e;
1978
  if (e.should_commit()) {
1979
    e.set_id(cast_from_oop<u8>(chunk));
1980
    e.set_size(thaw_size << LogBytesPerWord);
1981
    e.set_full(!partial);
1982
    e.commit();
1983
  }
1984
#endif
1985

1986
#ifdef ASSERT
1987
  set_anchor(_thread, rs.sp());
1988
  log_frames(_thread);
1989
  if (LoomDeoptAfterThaw) {
1990
    do_deopt_after_thaw(_thread);
1991
  }
1992
  clear_anchor(_thread);
1993
#endif
1994

1995
  return rs.sp();
1996
}
1997

1998
inline bool ThawBase::seen_by_gc() {
1999
  return _barriers || _cont.tail()->is_gc_mode();
2000
}
2001

2002
NOINLINE intptr_t* ThawBase::thaw_slow(stackChunkOop chunk, bool return_barrier) {
2003
  LogTarget(Trace, continuations) lt;
2004
  if (lt.develop_is_enabled()) {
2005
    LogStream ls(lt);
2006
    ls.print_cr("thaw slow return_barrier: %d " INTPTR_FORMAT, return_barrier, p2i(chunk));
2007
    chunk->print_on(true, &ls);
2008
  }
2009

2010
#if CONT_JFR
2011
  EventContinuationThawSlow e;
2012
  if (e.should_commit()) {
2013
    e.set_id(cast_from_oop<u8>(_cont.continuation()));
2014
    e.commit();
2015
  }
2016
#endif
2017

2018
  DEBUG_ONLY(_frames = 0;)
2019
  _align_size = 0;
2020
  int num_frames = (return_barrier ? 1 : 2);
2021

2022
  _stream = StackChunkFrameStream<ChunkFrames::Mixed>(chunk);
2023
  _top_unextended_sp_before_thaw = _stream.unextended_sp();
2024

2025
  frame heap_frame = _stream.to_frame();
2026
  if (lt.develop_is_enabled()) {
2027
    LogStream ls(lt);
2028
    ls.print_cr("top hframe before (thaw):");
2029
    assert(heap_frame.is_heap_frame(), "should have created a relative frame");
2030
    heap_frame.print_value_on(&ls, nullptr);
2031
  }
2032

2033
#if INCLUDE_ZGC || INCLUDE_SHENANDOAHGC
2034
  if (UseZGC || UseShenandoahGC) {
2035
    _cont.tail()->relativize_derived_pointers_concurrently();
2036
  }
2037
#endif
2038

2039
  frame caller; // the thawed caller on the stack
2040
  recurse_thaw(heap_frame, caller, num_frames, true);
2041
  finish_thaw(caller); // caller is now the topmost thawed frame
2042
  _cont.write();
2043

2044
  assert(_cont.chunk_invariant(), "");
2045

2046
  JVMTI_ONLY(if (!return_barrier) invalidate_jvmti_stack(_thread));
2047

2048
  _thread->set_cont_fastpath(_fastpath);
2049

2050
  intptr_t* sp = caller.sp();
2051
  return sp;
2052
}
2053

2054
void ThawBase::recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top) {
2055
  log_develop_debug(continuations)("thaw num_frames: %d", num_frames);
2056
  assert(!_cont.is_empty(), "no more frames");
2057
  assert(num_frames > 0, "");
2058
  assert(!heap_frame.is_empty(), "");
2059

2060
  if (top && heap_frame.is_safepoint_blob_frame()) {
2061
    assert(ContinuationHelper::Frame::is_stub(heap_frame.cb()), "cb: %s", heap_frame.cb()->name());
2062
    recurse_thaw_stub_frame(heap_frame, caller, num_frames);
2063
  } else if (!heap_frame.is_interpreted_frame()) {
2064
    recurse_thaw_compiled_frame(heap_frame, caller, num_frames, false);
2065
  } else {
2066
    recurse_thaw_interpreted_frame(heap_frame, caller, num_frames);
2067
  }
2068
}
2069

2070
template<typename FKind>
2071
bool ThawBase::recurse_thaw_java_frame(frame& caller, int num_frames) {
2072
  assert(num_frames > 0, "");
2073

2074
  DEBUG_ONLY(_frames++;)
2075

2076
  int argsize = _stream.stack_argsize();
2077

2078
  _stream.next(SmallRegisterMap::instance);
2079
  assert(_stream.to_frame().is_empty() == _stream.is_done(), "");
2080

2081
  // we never leave a compiled caller of an interpreted frame as the top frame in the chunk
2082
  // as it makes detecting that situation and adjusting unextended_sp tricky
2083
  if (num_frames == 1 && !_stream.is_done() && FKind::interpreted && _stream.is_compiled()) {
2084
    log_develop_trace(continuations)("thawing extra compiled frame to not leave a compiled interpreted-caller at top");
2085
    num_frames++;
2086
  }
2087

2088
  if (num_frames == 1 || _stream.is_done()) { // end recursion
2089
    finalize_thaw(caller, FKind::interpreted ? 0 : argsize);
2090
    return true; // bottom
2091
  } else { // recurse
2092
    recurse_thaw(_stream.to_frame(), caller, num_frames - 1, false);
2093
    return false;
2094
  }
2095
}
2096

2097
void ThawBase::finalize_thaw(frame& entry, int argsize) {
2098
  stackChunkOop chunk = _cont.tail();
2099

2100
  if (!_stream.is_done()) {
2101
    assert(_stream.sp() >= chunk->sp_address(), "");
2102
    chunk->set_sp(chunk->to_offset(_stream.sp()));
2103
    chunk->set_pc(_stream.pc());
2104
  } else {
2105
    chunk->set_sp(chunk->bottom());
2106
    chunk->set_pc(nullptr);
2107
  }
2108
  assert(_stream.is_done() == chunk->is_empty(), "");
2109

2110
  int total_thawed = pointer_delta_as_int(_stream.unextended_sp(), _top_unextended_sp_before_thaw);
2111
  chunk->set_max_thawing_size(chunk->max_thawing_size() - total_thawed);
2112

2113
  _cont.set_argsize(argsize);
2114
  entry = new_entry_frame();
2115

2116
  assert(entry.sp() == _cont.entrySP(), "");
2117
  assert(Continuation::is_continuation_enterSpecial(entry), "");
2118
  assert(_cont.is_entry_frame(entry), "");
2119
}
2120

2121
inline void ThawBase::before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame) {
2122
  LogTarget(Trace, continuations) lt;
2123
  if (lt.develop_is_enabled()) {
2124
    LogStream ls(lt);
2125
    ls.print_cr("======== THAWING FRAME: %d", num_frame);
2126
    assert(hf.is_heap_frame(), "should be");
2127
    hf.print_value_on(&ls, nullptr);
2128
  }
2129
  assert(bottom == _cont.is_entry_frame(caller), "bottom: %d is_entry_frame: %d", bottom, _cont.is_entry_frame(hf));
2130
}
2131

2132
inline void ThawBase::after_thaw_java_frame(const frame& f, bool bottom) {
2133
#ifdef ASSERT
2134
  LogTarget(Trace, continuations) lt;
2135
  if (lt.develop_is_enabled()) {
2136
    LogStream ls(lt);
2137
    ls.print_cr("thawed frame:");
2138
    print_frame_layout(f, false, &ls); // f.print_on(&ls);
2139
  }
2140
#endif
2141
}
2142

2143
inline void ThawBase::patch(frame& f, const frame& caller, bool bottom) {
2144
  assert(!bottom || caller.fp() == _cont.entryFP(), "");
2145
  if (bottom) {
2146
    ContinuationHelper::Frame::patch_pc(caller, _cont.is_empty() ? caller.pc()
2147
                                                                 : StubRoutines::cont_returnBarrier());
2148
  } else {
2149
    // caller might have been deoptimized during thaw but we've overwritten the return address when copying f from the heap.
2150
    // If the caller is not deoptimized, pc is unchanged.
2151
    ContinuationHelper::Frame::patch_pc(caller, caller.raw_pc());
2152
  }
2153

2154
  patch_pd(f, caller);
2155

2156
  if (f.is_interpreted_frame()) {
2157
    ContinuationHelper::InterpretedFrame::patch_sender_sp(f, caller);
2158
  }
2159

2160
  assert(!bottom || !_cont.is_empty() || Continuation::is_continuation_entry_frame(f, nullptr), "");
2161
  assert(!bottom || (_cont.is_empty() != Continuation::is_cont_barrier_frame(f)), "");
2162
}
2163

2164
void ThawBase::clear_bitmap_bits(address start, address end) {
2165
  assert(is_aligned(start, wordSize), "should be aligned: " PTR_FORMAT, p2i(start));
2166
  assert(is_aligned(end, VMRegImpl::stack_slot_size), "should be aligned: " PTR_FORMAT, p2i(end));
2167

2168
  // we need to clear the bits that correspond to arguments as they reside in the caller frame
2169
  // or they will keep objects that are otherwise unreachable alive.
2170

2171
  // Align `end` if UseCompressedOops is not set to avoid UB when calculating the bit index, since
2172
  // `end` could be at an odd number of stack slots from `start`, i.e might not be oop aligned.
2173
  // If that's the case the bit range corresponding to the last stack slot should not have bits set
2174
  // anyways and we assert that before returning.
2175
  address effective_end = UseCompressedOops ? end : align_down(end, wordSize);
2176
  log_develop_trace(continuations)("clearing bitmap for " INTPTR_FORMAT " - " INTPTR_FORMAT, p2i(start), p2i(effective_end));
2177
  stackChunkOop chunk = _cont.tail();
2178
  chunk->bitmap().clear_range(chunk->bit_index_for(start), chunk->bit_index_for(effective_end));
2179
  assert(effective_end == end || !chunk->bitmap().at(chunk->bit_index_for(effective_end)), "bit should not be set");
2180
}
2181

2182
NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames) {
2183
  assert(hf.is_interpreted_frame(), "");
2184

2185
  if (UNLIKELY(seen_by_gc())) {
2186
    _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2187
  }
2188

2189
  const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::InterpretedFrame>(caller, num_frames);
2190

2191
  DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2192

2193
  _align_size += frame::align_wiggle; // possible added alignment for internal interpreted frame alignment om AArch64
2194

2195
  frame f = new_stack_frame<ContinuationHelper::InterpretedFrame>(hf, caller, is_bottom_frame);
2196

2197
  intptr_t* const stack_frame_top = f.sp() + frame::metadata_words_at_top;
2198
  intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
2199
  intptr_t* const heap_frame_top = hf.unextended_sp() + frame::metadata_words_at_top;
2200
  intptr_t* const heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
2201

2202
  assert(hf.is_heap_frame(), "should be");
2203
  assert(!f.is_heap_frame(), "should not be");
2204

2205
  const int fsize = pointer_delta_as_int(heap_frame_bottom, heap_frame_top);
2206
  assert((stack_frame_bottom == stack_frame_top + fsize), "");
2207

2208
  // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
2209
  // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
2210
  copy_from_chunk(heap_frame_top, stack_frame_top, fsize);
2211

2212
  // Make sure the relativized locals is already set.
2213
  assert(f.interpreter_frame_local_at(0) == stack_frame_bottom - 1, "invalid frame bottom");
2214

2215
  derelativize_interpreted_frame_metadata(hf, f);
2216
  patch(f, caller, is_bottom_frame);
2217

2218
  assert(f.is_interpreted_frame_valid(_cont.thread()), "invalid thawed frame");
2219
  assert(stack_frame_bottom <= ContinuationHelper::Frame::frame_top(caller), "");
2220

2221
  CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
2222

2223
  maybe_set_fastpath(f.sp());
2224

2225
  const int locals = hf.interpreter_frame_method()->max_locals();
2226

2227
  if (!is_bottom_frame) {
2228
    // can only fix caller once this frame is thawed (due to callee saved regs)
2229
    _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2230
  } else if (_cont.tail()->has_bitmap() && locals > 0) {
2231
    assert(hf.is_heap_frame(), "should be");
2232
    address start = (address)(heap_frame_bottom - locals);
2233
    address end = (address)heap_frame_bottom;
2234
    clear_bitmap_bits(start, end);
2235
  }
2236

2237
  DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2238
  caller = f;
2239
}
2240

2241
void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller) {
2242
  assert(!hf.is_interpreted_frame(), "");
2243
  assert(_cont.is_preempted() || !stub_caller, "stub caller not at preemption");
2244

2245
  if (!stub_caller && UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2246
    _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2247
  }
2248

2249
  const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::CompiledFrame>(caller, num_frames);
2250

2251
  DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2252

2253
  assert(caller.sp() == caller.unextended_sp(), "");
2254

2255
  if ((!is_bottom_frame && caller.is_interpreted_frame()) || (is_bottom_frame && Interpreter::contains(_cont.tail()->pc()))) {
2256
    _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in freeze_interpreted_frame
2257
  }
2258

2259
  // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2260
  // yet laid out in the stack, and so the original_pc is not stored in it.
2261
  // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2262
  frame f = new_stack_frame<ContinuationHelper::CompiledFrame>(hf, caller, is_bottom_frame);
2263
  intptr_t* const stack_frame_top = f.sp();
2264
  intptr_t* const heap_frame_top = hf.unextended_sp();
2265

2266
  const int added_argsize = (is_bottom_frame || caller.is_interpreted_frame()) ? hf.compiled_frame_stack_argsize() : 0;
2267
  int fsize = ContinuationHelper::CompiledFrame::size(hf) + added_argsize;
2268
  assert(fsize <= (int)(caller.unextended_sp() - f.unextended_sp()), "");
2269

2270
  intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2271
  intptr_t* to   = stack_frame_top - frame::metadata_words_at_bottom;
2272
  // copy metadata, except the metadata at the top of the (unextended) entry frame
2273
  int sz = fsize + frame::metadata_words_at_bottom + (is_bottom_frame && added_argsize == 0 ? 0 : frame::metadata_words_at_top);
2274

2275
  // If we're the bottom-most thawed frame, we're writing to within one word from entrySP
2276
  // (we might have one padding word for alignment)
2277
  assert(!is_bottom_frame || (_cont.entrySP() - 1 <= to + sz && to + sz <= _cont.entrySP()), "");
2278
  assert(!is_bottom_frame || hf.compiled_frame_stack_argsize() != 0 || (to + sz && to + sz == _cont.entrySP()), "");
2279

2280
  copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2281

2282
  patch(f, caller, is_bottom_frame);
2283

2284
  // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2285
  assert(!f.is_deoptimized_frame(), "");
2286
  if (hf.is_deoptimized_frame()) {
2287
    maybe_set_fastpath(f.sp());
2288
  } else if (_thread->is_interp_only_mode()
2289
              || (_cont.is_preempted() && f.cb()->as_nmethod()->is_marked_for_deoptimization())) {
2290
    // The caller of the safepoint stub when the continuation is preempted is not at a call instruction, and so
2291
    // cannot rely on nmethod patching for deopt.
2292
    assert(_thread->is_interp_only_mode() || stub_caller, "expected a stub-caller");
2293

2294
    log_develop_trace(continuations)("Deoptimizing thawed frame");
2295
    DEBUG_ONLY(ContinuationHelper::Frame::patch_pc(f, nullptr));
2296

2297
    f.deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2298
    assert(f.is_deoptimized_frame(), "");
2299
    assert(ContinuationHelper::Frame::is_deopt_return(f.raw_pc(), f), "");
2300
    maybe_set_fastpath(f.sp());
2301
  }
2302

2303
  if (!is_bottom_frame) {
2304
    // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2305
    _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2306
  } else if (_cont.tail()->has_bitmap() && added_argsize > 0) {
2307
    address start = (address)(heap_frame_top + ContinuationHelper::CompiledFrame::size(hf) + frame::metadata_words_at_top);
2308
    int stack_args_slots = f.cb()->as_nmethod()->num_stack_arg_slots(false /* rounded */);
2309
    int argsize_in_bytes = stack_args_slots * VMRegImpl::stack_slot_size;
2310
    clear_bitmap_bits(start, start + argsize_in_bytes);
2311
  }
2312

2313
  DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2314
  caller = f;
2315
}
2316

2317
void ThawBase::recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames) {
2318
  DEBUG_ONLY(_frames++;)
2319

2320
  {
2321
    RegisterMap map(nullptr,
2322
                    RegisterMap::UpdateMap::include,
2323
                    RegisterMap::ProcessFrames::skip,
2324
                    RegisterMap::WalkContinuation::skip);
2325
    map.set_include_argument_oops(false);
2326
    _stream.next(&map);
2327
    assert(!_stream.is_done(), "");
2328
    if (UNLIKELY(seen_by_gc())) { // we're now doing this on the stub's caller
2329
      _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, &map);
2330
    }
2331
    assert(!_stream.is_done(), "");
2332
  }
2333

2334
  recurse_thaw_compiled_frame(_stream.to_frame(), caller, num_frames, true); // this could be deoptimized
2335

2336
  DEBUG_ONLY(before_thaw_java_frame(hf, caller, false, num_frames);)
2337

2338
  assert(ContinuationHelper::Frame::is_stub(hf.cb()), "");
2339
  assert(caller.sp() == caller.unextended_sp(), "");
2340
  assert(!caller.is_interpreted_frame(), "");
2341

2342
  int fsize = ContinuationHelper::StubFrame::size(hf);
2343

2344
  frame f = new_stack_frame<ContinuationHelper::StubFrame>(hf, caller, false);
2345
  intptr_t* stack_frame_top = f.sp();
2346
  intptr_t* heap_frame_top = hf.sp();
2347

2348
  copy_from_chunk(heap_frame_top - frame::metadata_words, stack_frame_top - frame::metadata_words,
2349
                  fsize + frame::metadata_words);
2350

2351
  { // can only fix caller once this frame is thawed (due to callee saved regs)
2352
    RegisterMap map(nullptr,
2353
                    RegisterMap::UpdateMap::include,
2354
                    RegisterMap::ProcessFrames::skip,
2355
                    RegisterMap::WalkContinuation::skip); // map.clear();
2356
    map.set_include_argument_oops(false);
2357
    f.oop_map()->update_register_map(&f, &map);
2358
    ContinuationHelper::update_register_map_with_callee(caller, &map);
2359
    _cont.tail()->fix_thawed_frame(caller, &map);
2360
  }
2361

2362
  DEBUG_ONLY(after_thaw_java_frame(f, false);)
2363
  caller = f;
2364
}
2365

2366
void ThawBase::finish_thaw(frame& f) {
2367
  stackChunkOop chunk = _cont.tail();
2368

2369
  if (chunk->is_empty()) {
2370
    // Only remove chunk from list if it can't be reused for another freeze
2371
    if (seen_by_gc()) {
2372
      _cont.set_tail(chunk->parent());
2373
    } else {
2374
      chunk->set_has_mixed_frames(false);
2375
    }
2376
    chunk->set_max_thawing_size(0);
2377
  } else {
2378
    chunk->set_max_thawing_size(chunk->max_thawing_size() - _align_size);
2379
  }
2380
  assert(chunk->is_empty() == (chunk->max_thawing_size() == 0), "");
2381

2382
  if (!is_aligned(f.sp(), frame::frame_alignment)) {
2383
    assert(f.is_interpreted_frame(), "");
2384
    f.set_sp(align_down(f.sp(), frame::frame_alignment));
2385
  }
2386
  push_return_frame(f);
2387
  chunk->fix_thawed_frame(f, SmallRegisterMap::instance); // can only fix caller after push_return_frame (due to callee saved regs)
2388

2389
  assert(_cont.is_empty() == _cont.last_frame().is_empty(), "");
2390

2391
  log_develop_trace(continuations)("thawed %d frames", _frames);
2392

2393
  LogTarget(Trace, continuations) lt;
2394
  if (lt.develop_is_enabled()) {
2395
    LogStream ls(lt);
2396
    ls.print_cr("top hframe after (thaw):");
2397
    _cont.last_frame().print_value_on(&ls, nullptr);
2398
  }
2399
}
2400

2401
void ThawBase::push_return_frame(frame& f) { // see generate_cont_thaw
2402
  assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
2403
  assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == (f.pc() != f.raw_pc()), "");
2404

2405
  LogTarget(Trace, continuations) lt;
2406
  if (lt.develop_is_enabled()) {
2407
    LogStream ls(lt);
2408
    ls.print_cr("push_return_frame");
2409
    f.print_value_on(&ls, nullptr);
2410
  }
2411

2412
  assert(f.sp() - frame::metadata_words_at_bottom >= _top_stack_address, "overwrote past thawing space"
2413
    " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(f.sp() - frame::metadata_words), p2i(_top_stack_address));
2414
  ContinuationHelper::Frame::patch_pc(f, f.raw_pc()); // in case we want to deopt the frame in a full transition, this is checked.
2415
  ContinuationHelper::push_pd(f);
2416

2417
  assert(ContinuationHelper::Frame::assert_frame_laid_out(f), "");
2418
}
2419

2420
// returns new top sp
2421
// called after preparations (stack overflow check and making room)
2422
template<typename ConfigT>
2423
static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind) {
2424
  assert(thread == JavaThread::current(), "Must be current thread");
2425

2426
  CONT_JFR_ONLY(EventContinuationThaw event;)
2427

2428
  log_develop_trace(continuations)("~~~~ thaw kind: %d sp: " INTPTR_FORMAT, kind, p2i(thread->last_continuation()->entry_sp()));
2429

2430
  ContinuationEntry* entry = thread->last_continuation();
2431
  assert(entry != nullptr, "");
2432
  oop oopCont = entry->cont_oop(thread);
2433

2434
  assert(!jdk_internal_vm_Continuation::done(oopCont), "");
2435
  assert(oopCont == get_continuation(thread), "");
2436
  verify_continuation(oopCont);
2437

2438
  assert(entry->is_virtual_thread() == (entry->scope(thread) == java_lang_VirtualThread::vthread_scope()), "");
2439

2440
  ContinuationWrapper cont(thread, oopCont);
2441
  log_develop_debug(continuations)("THAW #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
2442

2443
#ifdef ASSERT
2444
  set_anchor_to_entry(thread, cont.entry());
2445
  log_frames(thread);
2446
  clear_anchor(thread);
2447
#endif
2448

2449
  Thaw<ConfigT> thw(thread, cont);
2450
  intptr_t* const sp = thw.thaw(kind);
2451
  assert(is_aligned(sp, frame::frame_alignment), "");
2452

2453
  // All or part of the frames have been thawed so we know they don't hold any monitors except JNI monitors.
2454
  assert(thread->held_monitor_count() == thread->jni_monitor_count(), "Must be");
2455

2456
#ifdef ASSERT
2457
  intptr_t* sp0 = sp;
2458
  set_anchor(thread, sp0);
2459
  log_frames(thread);
2460
  if (LoomVerifyAfterThaw) {
2461
    assert(do_verify_after_thaw(thread, cont.tail(), tty), "");
2462
  }
2463
  assert(ContinuationEntry::assert_entry_frame_laid_out(thread), "");
2464
  clear_anchor(thread);
2465

2466
  LogTarget(Trace, continuations) lt;
2467
  if (lt.develop_is_enabled()) {
2468
    LogStream ls(lt);
2469
    ls.print_cr("Jumping to frame (thaw):");
2470
    frame(sp).print_value_on(&ls, nullptr);
2471
  }
2472
#endif
2473

2474
  CONT_JFR_ONLY(thw.jfr_info().post_jfr_event(&event, cont.continuation(), thread);)
2475

2476
  verify_continuation(cont.continuation());
2477
  log_develop_debug(continuations)("=== End of thaw #" INTPTR_FORMAT, cont.hash());
2478

2479
  return sp;
2480
}
2481

2482
#ifdef ASSERT
2483
static void do_deopt_after_thaw(JavaThread* thread) {
2484
  int i = 0;
2485
  StackFrameStream fst(thread, true, false);
2486
  fst.register_map()->set_include_argument_oops(false);
2487
  ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2488
  for (; !fst.is_done(); fst.next()) {
2489
    if (fst.current()->cb()->is_nmethod()) {
2490
      nmethod* nm = fst.current()->cb()->as_nmethod();
2491
      if (!nm->method()->is_continuation_native_intrinsic()) {
2492
        nm->make_deoptimized();
2493
      }
2494
    }
2495
  }
2496
}
2497

2498
class ThawVerifyOopsClosure: public OopClosure {
2499
  intptr_t* _p;
2500
  outputStream* _st;
2501
  bool is_good_oop(oop o) {
2502
    return dbg_is_safe(o, -1) && dbg_is_safe(o->klass(), -1) && oopDesc::is_oop(o) && o->klass()->is_klass();
2503
  }
2504
public:
2505
  ThawVerifyOopsClosure(outputStream* st) : _p(nullptr), _st(st) {}
2506
  intptr_t* p() { return _p; }
2507
  void reset() { _p = nullptr; }
2508

2509
  virtual void do_oop(oop* p) {
2510
    oop o = *p;
2511
    if (o == nullptr || is_good_oop(o)) {
2512
      return;
2513
    }
2514
    _p = (intptr_t*)p;
2515
    _st->print_cr("*** non-oop " PTR_FORMAT " found at " PTR_FORMAT, p2i(*p), p2i(p));
2516
  }
2517
  virtual void do_oop(narrowOop* p) {
2518
    oop o = RawAccess<>::oop_load(p);
2519
    if (o == nullptr || is_good_oop(o)) {
2520
      return;
2521
    }
2522
    _p = (intptr_t*)p;
2523
    _st->print_cr("*** (narrow) non-oop %x found at " PTR_FORMAT, (int)(*p), p2i(p));
2524
  }
2525
};
2526

2527
static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st) {
2528
  assert(thread->has_last_Java_frame(), "");
2529

2530
  ResourceMark rm;
2531
  ThawVerifyOopsClosure cl(st);
2532
  NMethodToOopClosure cf(&cl, false);
2533

2534
  StackFrameStream fst(thread, true, false);
2535
  fst.register_map()->set_include_argument_oops(false);
2536
  ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2537
  for (; !fst.is_done() && !Continuation::is_continuation_enterSpecial(*fst.current()); fst.next()) {
2538
    if (fst.current()->cb()->is_nmethod() && fst.current()->cb()->as_nmethod()->is_marked_for_deoptimization()) {
2539
      st->print_cr(">>> do_verify_after_thaw deopt");
2540
      fst.current()->deoptimize(nullptr);
2541
      fst.current()->print_on(st);
2542
    }
2543

2544
    fst.current()->oops_do(&cl, &cf, fst.register_map());
2545
    if (cl.p() != nullptr) {
2546
      frame fr = *fst.current();
2547
      st->print_cr("Failed for frame barriers: %d",chunk->requires_barriers());
2548
      fr.print_on(st);
2549
      if (!fr.is_interpreted_frame()) {
2550
        st->print_cr("size: %d argsize: %d",
2551
                     ContinuationHelper::NonInterpretedUnknownFrame::size(fr),
2552
                     ContinuationHelper::NonInterpretedUnknownFrame::stack_argsize(fr));
2553
      }
2554
      VMReg reg = fst.register_map()->find_register_spilled_here(cl.p(), fst.current()->sp());
2555
      if (reg != nullptr) {
2556
        st->print_cr("Reg %s %d", reg->name(), reg->is_stack() ? (int)reg->reg2stack() : -99);
2557
      }
2558
      cl.reset();
2559
      DEBUG_ONLY(thread->print_frame_layout();)
2560
      if (chunk != nullptr) {
2561
        chunk->print_on(true, st);
2562
      }
2563
      return false;
2564
    }
2565
  }
2566
  return true;
2567
}
2568

2569
static void log_frames(JavaThread* thread) {
2570
  const static int show_entry_callers = 3;
2571
  LogTarget(Trace, continuations) lt;
2572
  if (!lt.develop_is_enabled()) {
2573
    return;
2574
  }
2575
  LogStream ls(lt);
2576

2577
  ls.print_cr("------- frames ---------");
2578
  if (!thread->has_last_Java_frame()) {
2579
    ls.print_cr("NO ANCHOR!");
2580
  }
2581

2582
  RegisterMap map(thread,
2583
                  RegisterMap::UpdateMap::include,
2584
                  RegisterMap::ProcessFrames::include,
2585
                  RegisterMap::WalkContinuation::skip);
2586
  map.set_include_argument_oops(false);
2587

2588
  if (false) {
2589
    for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
2590
      f.print_on(&ls);
2591
    }
2592
  } else {
2593
    map.set_skip_missing(true);
2594
    ResetNoHandleMark rnhm;
2595
    ResourceMark rm;
2596
    HandleMark hm(Thread::current());
2597
    FrameValues values;
2598

2599
    int i = 0;
2600
    int post_entry = -1;
2601
    for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
2602
      f.describe(values, i++, &map);
2603
      if (post_entry >= 0 || Continuation::is_continuation_enterSpecial(f))
2604
        post_entry++;
2605
      if (post_entry >= show_entry_callers)
2606
        break;
2607
    }
2608
    values.print_on(thread, &ls);
2609
  }
2610

2611
  ls.print_cr("======= end frames =========");
2612
}
2613
#endif // ASSERT
2614

2615
#include CPU_HEADER_INLINE(continuationFreezeThaw)
2616

2617
#ifdef ASSERT
2618
static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st) {
2619
  ResourceMark rm;
2620
  FrameValues values;
2621
  assert(f.get_cb() != nullptr, "");
2622
  RegisterMap map(f.is_heap_frame() ?
2623
                    nullptr :
2624
                    JavaThread::current(),
2625
                  RegisterMap::UpdateMap::include,
2626
                  RegisterMap::ProcessFrames::skip,
2627
                  RegisterMap::WalkContinuation::skip);
2628
  map.set_include_argument_oops(false);
2629
  map.set_skip_missing(true);
2630
  if (callee_complete) {
2631
    frame::update_map_with_saved_link(&map, ContinuationHelper::Frame::callee_link_address(f));
2632
  }
2633
  const_cast<frame&>(f).describe(values, 0, &map);
2634
  values.print_on(static_cast<JavaThread*>(nullptr), st);
2635
}
2636
#endif
2637

2638
static address thaw_entry   = nullptr;
2639
static address freeze_entry = nullptr;
2640

2641
address Continuation::thaw_entry() {
2642
  return ::thaw_entry;
2643
}
2644

2645
address Continuation::freeze_entry() {
2646
  return ::freeze_entry;
2647
}
2648

2649
class ConfigResolve {
2650
public:
2651
  static void resolve() { resolve_compressed(); }
2652

2653
  static void resolve_compressed() {
2654
    UseCompressedOops ? resolve_gc<true>()
2655
                      : resolve_gc<false>();
2656
  }
2657

2658
private:
2659
  template <bool use_compressed>
2660
  static void resolve_gc() {
2661
    BarrierSet* bs = BarrierSet::barrier_set();
2662
    assert(bs != nullptr, "freeze/thaw invoked before BarrierSet is set");
2663
    switch (bs->kind()) {
2664
#define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name)                    \
2665
      case BarrierSet::bs_name: {                                       \
2666
        resolve<use_compressed, typename BarrierSet::GetType<BarrierSet::bs_name>::type>(); \
2667
      }                                                                 \
2668
        break;
2669
      FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)
2670
#undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE
2671

2672
    default:
2673
      fatal("BarrierSet resolving not implemented");
2674
    };
2675
  }
2676

2677
  template <bool use_compressed, typename BarrierSetT>
2678
  static void resolve() {
2679
    typedef Config<use_compressed ? oop_kind::NARROW : oop_kind::WIDE, BarrierSetT> SelectedConfigT;
2680

2681
    freeze_entry = (address)freeze<SelectedConfigT>;
2682

2683
    // If we wanted, we could templatize by kind and have three different thaw entries
2684
    thaw_entry   = (address)thaw<SelectedConfigT>;
2685
  }
2686
};
2687

2688
void Continuation::init() {
2689
  ConfigResolve::resolve();
2690
}
2691