/*

 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "classfile/systemDictionary.hpp"

#include "code/codeBehaviours.hpp"

#include "code/codeCache.hpp"

#include "code/compiledIC.hpp"

#include "code/icBuffer.hpp"

#include "code/nmethod.hpp"

#include "code/vtableStubs.hpp"

#include "interpreter/interpreter.hpp"

#include "interpreter/linkResolver.hpp"

#include "memory/metadataFactory.hpp"

#include "memory/oopFactory.hpp"

#include "memory/resourceArea.hpp"

#include "memory/universe.hpp"

#include "oops/method.inline.hpp"

#include "oops/oop.inline.hpp"

#include "oops/symbol.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/icache.hpp"

#include "runtime/sharedRuntime.hpp"

#include "runtime/stubRoutines.hpp"

#include "utilities/events.hpp"

// Every time a compiled IC is changed or its type is being accessed,

// either the CompiledIC_lock must be set or we must be at a safe point.

CompiledICLocker::CompiledICLocker(CompiledMethod* method)

  : _method(method),

    _behaviour(CompiledICProtectionBehaviour::current()),

    _locked(_behaviour->lock(_method)) {

}

CompiledICLocker::~CompiledICLocker() {

  if (_locked) {

    _behaviour->unlock(_method);

  }

}

bool CompiledICLocker::is_safe(CompiledMethod* method) {

  return CompiledICProtectionBehaviour::current()->is_safe(method);

}

bool CompiledICLocker::is_safe(address code) {

  CodeBlob* cb = CodeCache::find_blob_unsafe(code);

  assert(cb != NULL && cb->is_compiled(), "must be compiled");

  CompiledMethod* cm = cb->as_compiled_method();

  return CompiledICProtectionBehaviour::current()->is_safe(cm);

}

//-----------------------------------------------------------------------------

// Low-level access to an inline cache. Private, since they might not be

// MT-safe to use.

void* CompiledIC::cached_value() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  assert (!is_optimized(), "an optimized virtual call does not have a cached metadata");

  if (!is_in_transition_state()) {

    void* data = get_data();

    // If we let the metadata value here be initialized to zero...

    assert(data != NULL || Universe::non_oop_word() == NULL,

           "no raw nulls in CompiledIC metadatas, because of patching races");

    return (data == (void*)Universe::non_oop_word()) ? NULL : data;

  } else {

    return InlineCacheBuffer::cached_value_for((CompiledIC *)this);

  }

}

void CompiledIC::internal_set_ic_destination(address entry_point, bool is_icstub, void* cache, bool is_icholder) {

  assert(entry_point != NULL, "must set legal entry point");

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  assert (!is_optimized() || cache == NULL, "an optimized virtual call does not have a cached metadata");

  assert (cache == NULL || cache != (Metadata*)badOopVal, "invalid metadata");

  assert(!is_icholder || is_icholder_entry(entry_point), "must be");

  // Don't use ic_destination for this test since that forwards

  // through ICBuffer instead of returning the actual current state of

  // the CompiledIC.

  if (is_icholder_entry(_call->destination())) {

    // When patching for the ICStub case the cached value isn't

    // overwritten until the ICStub copied into the CompiledIC during

    // the next safepoint.  Make sure that the CompiledICHolder* is

    // marked for release at this point since it won't be identifiable

    // once the entry point is overwritten.

    InlineCacheBuffer::queue_for_release((CompiledICHolder*)get_data());

  }

  if (TraceCompiledIC) {

    tty->print("  ");

    print_compiled_ic();

    tty->print(" changing destination to " INTPTR_FORMAT, p2i(entry_point));

    if (!is_optimized()) {

      tty->print(" changing cached %s to " INTPTR_FORMAT, is_icholder ? "icholder" : "metadata", p2i((address)cache));

    }

    if (is_icstub) {

      tty->print(" (icstub)");

    }

    tty->cr();

  }

  {

    CodeBlob* cb = CodeCache::find_blob_unsafe(_call->instruction_address());

    assert(cb != NULL && cb->is_compiled(), "must be compiled");

    _call->set_destination_mt_safe(entry_point);

  }

  if (is_optimized() || is_icstub) {

    // Optimized call sites don't have a cache value and ICStub call

    // sites only change the entry point.  Changing the value in that

    // case could lead to MT safety issues.

    assert(cache == NULL, "must be null");

    return;

  }

  if (cache == NULL)  cache = (void*)Universe::non_oop_word();

  set_data((intptr_t)cache);

}

void CompiledIC::set_ic_destination(ICStub* stub) {

  internal_set_ic_destination(stub->code_begin(), true, NULL, false);

}

address CompiledIC::ic_destination() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  if (!is_in_transition_state()) {

    return _call->destination();

  } else {

    return InlineCacheBuffer::ic_destination_for((CompiledIC *)this);

  }

}

bool CompiledIC::is_in_transition_state() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  return InlineCacheBuffer::contains(_call->destination());;

}

bool CompiledIC::is_icholder_call() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  return !_is_optimized && is_icholder_entry(ic_destination());

}

// Returns native address of 'call' instruction in inline-cache. Used by

// the InlineCacheBuffer when it needs to find the stub.

address CompiledIC::stub_address() const {

  assert(is_in_transition_state(), "should only be called when we are in a transition state");

  return _call->destination();

}

// Clears the IC stub if the compiled IC is in transition state

void CompiledIC::clear_ic_stub() {

  if (is_in_transition_state()) {

    ICStub* stub = ICStub_from_destination_address(stub_address());

    stub->clear();

  }

}

//-----------------------------------------------------------------------------

// High-level access to an inline cache. Guaranteed to be MT-safe.

void CompiledIC::initialize_from_iter(RelocIterator* iter) {

  assert(iter->addr() == _call->instruction_address(), "must find ic_call");

  if (iter->type() == relocInfo::virtual_call_type) {

    virtual_call_Relocation* r = iter->virtual_call_reloc();

    _is_optimized = false;

    _value = _call->get_load_instruction(r);

  } else {

    assert(iter->type() == relocInfo::opt_virtual_call_type, "must be a virtual call");

    _is_optimized = true;

    _value = NULL;

  }

}

CompiledIC::CompiledIC(CompiledMethod* cm, NativeCall* call)

  : _method(cm)

{

  _call = _method->call_wrapper_at((address) call);

  address ic_call = _call->instruction_address();

  assert(ic_call != NULL, "ic_call address must be set");

  assert(cm != NULL, "must pass compiled method");

  assert(cm->contains(ic_call), "must be in compiled method");

  // Search for the ic_call at the given address.

  RelocIterator iter(cm, ic_call, ic_call+1);

  bool ret = iter.next();

  assert(ret == true, "relocInfo must exist at this address");

  assert(iter.addr() == ic_call, "must find ic_call");

  initialize_from_iter(&iter);

}

CompiledIC::CompiledIC(RelocIterator* iter)

  : _method(iter->code())

{

  _call = _method->call_wrapper_at(iter->addr());

  address ic_call = _call->instruction_address();

  CompiledMethod* nm = iter->code();

  assert(ic_call != NULL, "ic_call address must be set");

  assert(nm != NULL, "must pass compiled method");

  assert(nm->contains(ic_call), "must be in compiled method");

  initialize_from_iter(iter);

}

// This function may fail for two reasons: either due to running out of vtable

// stubs, or due to running out of IC stubs in an attempted transition to a

// transitional state. The needs_ic_stub_refill value will be set if the failure

// was due to running out of IC stubs, in which case the caller will refill IC

// stubs and retry.

bool CompiledIC::set_to_megamorphic(CallInfo* call_info, Bytecodes::Code bytecode,

                                    bool& needs_ic_stub_refill, TRAPS) {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  assert(!is_optimized(), "cannot set an optimized virtual call to megamorphic");

  assert(is_call_to_compiled() || is_call_to_interpreted(), "going directly to megamorphic?");

  address entry;

  if (call_info->call_kind() == CallInfo::itable_call) {

    assert(bytecode == Bytecodes::_invokeinterface, "");

    int itable_index = call_info->itable_index();

    entry = VtableStubs::find_itable_stub(itable_index);

    if (entry == NULL) {

      return false;

    }

#ifdef ASSERT

    int index = call_info->resolved_method()->itable_index();

    assert(index == itable_index, "CallInfo pre-computes this");

    InstanceKlass* k = call_info->resolved_method()->method_holder();

    assert(k->verify_itable_index(itable_index), "sanity check");

#endif //ASSERT

    CompiledICHolder* holder = new CompiledICHolder(call_info->resolved_method()->method_holder(),

                                                    call_info->resolved_klass(), false);

    holder->claim();

    if (!InlineCacheBuffer::create_transition_stub(this, holder, entry)) {

      delete holder;

      needs_ic_stub_refill = true;

      return false;

    }

  } else {

    assert(call_info->call_kind() == CallInfo::vtable_call, "either itable or vtable");

    // Can be different than selected_method->vtable_index(), due to package-private etc.

    int vtable_index = call_info->vtable_index();

    assert(call_info->resolved_klass()->verify_vtable_index(vtable_index), "sanity check");

    entry = VtableStubs::find_vtable_stub(vtable_index);

    if (entry == NULL) {

      return false;

    }

    if (!InlineCacheBuffer::create_transition_stub(this, NULL, entry)) {

      needs_ic_stub_refill = true;

      return false;

    }

  }

  if (TraceICs) {

    ResourceMark rm;

    tty->print_cr ("IC@" INTPTR_FORMAT ": to megamorphic %s entry: " INTPTR_FORMAT,

                   p2i(instruction_address()), call_info->selected_method()->print_value_string(), p2i(entry));

  }

  // We can't check this anymore. With lazy deopt we could have already

  // cleaned this IC entry before we even return. This is possible if

  // we ran out of space in the inline cache buffer trying to do the

  // set_next and we safepointed to free up space. This is a benign

  // race because the IC entry was complete when we safepointed so

  // cleaning it immediately is harmless.

  // assert(is_megamorphic(), "sanity check");

  return true;

}

// true if destination is megamorphic stub

bool CompiledIC::is_megamorphic() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  assert(!is_optimized(), "an optimized call cannot be megamorphic");

  // Cannot rely on cached_value. It is either an interface or a method.

  return VtableStubs::entry_point(ic_destination()) != NULL;

}

bool CompiledIC::is_call_to_compiled() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  // Use unsafe, since an inline cache might point to a zombie method. However, the zombie

  // method is guaranteed to still exist, since we only remove methods after all inline caches

  // has been cleaned up

  CodeBlob* cb = CodeCache::find_blob_unsafe(ic_destination());

  bool is_monomorphic = (cb != NULL && cb->is_compiled());

  // Check that the cached_value is a klass for non-optimized monomorphic calls

  // This assertion is invalid for compiler1: a call that does not look optimized (no static stub) can be used

  // for calling directly to vep without using the inline cache (i.e., cached_value == NULL).

  // For JVMCI this occurs because CHA is only used to improve inlining so call sites which could be optimized

  // virtuals because there are no currently loaded subclasses of a type are left as virtual call sites.

#ifdef ASSERT

  CodeBlob* caller = CodeCache::find_blob_unsafe(instruction_address());

  bool is_c1_or_jvmci_method = caller->is_compiled_by_c1() || caller->is_compiled_by_jvmci();

  assert( is_c1_or_jvmci_method ||

         !is_monomorphic ||

         is_optimized() ||

         !caller->is_alive() ||

         (cached_metadata() != NULL && cached_metadata()->is_klass()), "sanity check");

#endif // ASSERT

  return is_monomorphic;

}

bool CompiledIC::is_call_to_interpreted() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  // Call to interpreter if destination is either calling to a stub (if it

  // is optimized), or calling to an I2C blob

  bool is_call_to_interpreted = false;

  if (!is_optimized()) {

    // must use unsafe because the destination can be a zombie (and we're cleaning)

    // and the print_compiled_ic code wants to know if site (in the non-zombie)

    // is to the interpreter.

    CodeBlob* cb = CodeCache::find_blob_unsafe(ic_destination());

    is_call_to_interpreted = (cb != NULL && cb->is_adapter_blob());

    assert(!is_call_to_interpreted || (is_icholder_call() && cached_icholder() != NULL), "sanity check");

  } else {

    // Check if we are calling into our own codeblob (i.e., to a stub)

    address dest = ic_destination();

#ifdef ASSERT

    {

      _call->verify_resolve_call(dest);

    }

#endif /* ASSERT */

    is_call_to_interpreted = _call->is_call_to_interpreted(dest);

  }

  return is_call_to_interpreted;

}

bool CompiledIC::set_to_clean(bool in_use) {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  if (TraceInlineCacheClearing || TraceICs) {

    tty->print_cr("IC@" INTPTR_FORMAT ": set to clean", p2i(instruction_address()));

    print();

  }

  address entry = _call->get_resolve_call_stub(is_optimized());

  // A zombie transition will always be safe, since the metadata has already been set to NULL, so

  // we only need to patch the destination

  bool safe_transition = _call->is_safe_for_patching() || !in_use || is_optimized() || SafepointSynchronize::is_at_safepoint();

  if (safe_transition) {

    // Kill any leftover stub we might have too

    clear_ic_stub();

    if (is_optimized()) {

      set_ic_destination(entry);

    } else {

      set_ic_destination_and_value(entry, (void*)NULL);

    }

  } else {

    // Unsafe transition - create stub.

    if (!InlineCacheBuffer::create_transition_stub(this, NULL, entry)) {

      return false;

    }

  }

  // We can't check this anymore. With lazy deopt we could have already

  // cleaned this IC entry before we even return. This is possible if

  // we ran out of space in the inline cache buffer trying to do the

  // set_next and we safepointed to free up space. This is a benign

  // race because the IC entry was complete when we safepointed so

  // cleaning it immediately is harmless.

  // assert(is_clean(), "sanity check");

  return true;

}

bool CompiledIC::is_clean() const {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  bool is_clean = false;

  address dest = ic_destination();

  is_clean = dest == _call->get_resolve_call_stub(is_optimized());

  assert(!is_clean || is_optimized() || cached_value() == NULL, "sanity check");

  return is_clean;

}

bool CompiledIC::set_to_monomorphic(CompiledICInfo& info) {

  assert(CompiledICLocker::is_safe(_method), "mt unsafe call");

  // Updating a cache to the wrong entry can cause bugs that are very hard

  // to track down - if cache entry gets invalid - we just clean it. In

  // this way it is always the same code path that is responsible for

  // updating and resolving an inline cache

  //

  // The above is no longer true. SharedRuntime::fixup_callers_callsite will change optimized

  // callsites. In addition ic_miss code will update a site to monomorphic if it determines

  // that an monomorphic call to the interpreter can now be monomorphic to compiled code.

  //

  // In both of these cases the only thing being modifed is the jump/call target and these

  // transitions are mt_safe

  Thread *thread = Thread::current();

  if (info.to_interpreter() || info.to_aot()) {

    // Call to interpreter

    if (info.is_optimized() && is_optimized()) {

      assert(is_clean(), "unsafe IC path");

      // the call analysis (callee structure) specifies that the call is optimized

      // (either because of CHA or the static target is final)

      // At code generation time, this call has been emitted as static call

      // Call via stub

      assert(info.cached_metadata() != NULL && info.cached_metadata()->is_method(), "sanity check");

      methodHandle method (thread, (Method*)info.cached_metadata());

      _call->set_to_interpreted(method, info);

      if (TraceICs) {

         ResourceMark rm(thread);

         tty->print_cr ("IC@" INTPTR_FORMAT ": monomorphic to %s: %s",

           p2i(instruction_address()),

           (info.to_aot() ? "aot" : "interpreter"),

           method->print_value_string());

      }

    } else {

      // Call via method-klass-holder

      CompiledICHolder* holder = info.claim_cached_icholder();

      if (!InlineCacheBuffer::create_transition_stub(this, holder, info.entry())) {

        delete holder;

        return false;

      }

      if (TraceICs) {

         ResourceMark rm(thread);

         tty->print_cr ("IC@" INTPTR_FORMAT ": monomorphic to interpreter via icholder ", p2i(instruction_address()));

      }

    }

  } else {

    // Call to compiled code

    bool static_bound = info.is_optimized() || (info.cached_metadata() == NULL);

#ifdef ASSERT

    CodeBlob* cb = CodeCache::find_blob_unsafe(info.entry());

    assert (cb != NULL && cb->is_compiled(), "must be compiled!");

#endif /* ASSERT */

    // This is MT safe if we come from a clean-cache and go through a

    // non-verified entry point

    bool safe = SafepointSynchronize::is_at_safepoint() ||

                (!is_in_transition_state() && (info.is_optimized() || static_bound || is_clean()));

    if (!safe) {

      if (!InlineCacheBuffer::create_transition_stub(this, info.cached_metadata(), info.entry())) {

        return false;

      }

    } else {

      if (is_optimized()) {

        set_ic_destination(info.entry());

      } else {

        set_ic_destination_and_value(info.entry(), info.cached_metadata());

      }

    }

    if (TraceICs) {

      ResourceMark rm(thread);

      assert(info.cached_metadata() == NULL || info.cached_metadata()->is_klass(), "must be");

      tty->print_cr ("IC@" INTPTR_FORMAT ": monomorphic to compiled (rcvr klass = %s) %s",

        p2i(instruction_address()),

        (info.cached_metadata() != NULL) ? ((Klass*)info.cached_metadata())->print_value_string() : "NULL",

        (safe) ? "" : " via stub");

    }

  }

  // We can't check this anymore. With lazy deopt we could have already

  // cleaned this IC entry before we even return. This is possible if

  // we ran out of space in the inline cache buffer trying to do the

  // set_next and we safepointed to free up space. This is a benign

  // race because the IC entry was complete when we safepointed so