/*

 * Copyright (c) 2015, 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 "code/compiledIC.hpp"

#include "code/compiledMethod.inline.hpp"

#include "code/scopeDesc.hpp"

#include "code/codeCache.hpp"

#include "code/icBuffer.hpp"

#include "gc/shared/barrierSet.hpp"

#include "gc/shared/gcBehaviours.hpp"

#include "interpreter/bytecode.inline.hpp"

#include "logging/log.hpp"

#include "logging/logTag.hpp"

#include "memory/resourceArea.hpp"

#include "oops/methodData.hpp"

#include "oops/method.inline.hpp"

#include "prims/methodHandles.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/mutexLocker.hpp"

CompiledMethod::CompiledMethod(Method* method, const char* name, CompilerType type, const CodeBlobLayout& layout,

                               int frame_complete_offset, int frame_size, ImmutableOopMapSet* oop_maps,

                               bool caller_must_gc_arguments)

  : CodeBlob(name, type, layout, frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),

    _mark_for_deoptimization_status(not_marked),

    _method(method),

    _gc_data(NULL)

{

  init_defaults();

}

CompiledMethod::CompiledMethod(Method* method, const char* name, CompilerType type, int size,

                               int header_size, CodeBuffer* cb, int frame_complete_offset, int frame_size,

                               OopMapSet* oop_maps, bool caller_must_gc_arguments)

  : CodeBlob(name, type, CodeBlobLayout((address) this, size, header_size, cb), cb,

             frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),

    _mark_for_deoptimization_status(not_marked),

    _method(method),

    _gc_data(NULL)

{

  init_defaults();

}

void CompiledMethod::init_defaults() {

  _has_unsafe_access          = 0;

  _has_method_handle_invokes  = 0;

  _lazy_critical_native       = 0;

  _has_wide_vectors           = 0;

}

bool CompiledMethod::is_method_handle_return(address return_pc) {

  if (!has_method_handle_invokes())  return false;

  PcDesc* pd = pc_desc_at(return_pc);

  if (pd == NULL)

    return false;

  return pd->is_method_handle_invoke();

}

// Returns a string version of the method state.

const char* CompiledMethod::state() const {

  int state = get_state();

  switch (state) {

  case not_installed:

    return "not installed";

  case in_use:

    return "in use";

  case not_used:

    return "not_used";

  case not_entrant:

    return "not_entrant";

  case zombie:

    return "zombie";

  case unloaded:

    return "unloaded";

  default:

    fatal("unexpected method state: %d", state);

    return NULL;

  }

}

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

ExceptionCache* CompiledMethod::exception_cache_acquire() const {

  return OrderAccess::load_acquire(&_exception_cache);

}

void CompiledMethod::add_exception_cache_entry(ExceptionCache* new_entry) {

  assert(ExceptionCache_lock->owned_by_self(),"Must hold the ExceptionCache_lock");

  assert(new_entry != NULL,"Must be non null");

  assert(new_entry->next() == NULL, "Must be null");

  for (;;) {

    ExceptionCache *ec = exception_cache();

    if (ec != NULL) {

      Klass* ex_klass = ec->exception_type();

      if (!ex_klass->is_loader_alive()) {

        // We must guarantee that entries are not inserted with new next pointer

        // edges to ExceptionCache entries with dead klasses, due to bad interactions

        // with concurrent ExceptionCache cleanup. Therefore, the inserts roll

        // the head pointer forward to the first live ExceptionCache, so that the new

        // next pointers always point at live ExceptionCaches, that are not removed due

        // to concurrent ExceptionCache cleanup.

        ExceptionCache* next = ec->next();

        if (Atomic::cmpxchg(next, &_exception_cache, ec) == ec) {

          CodeCache::release_exception_cache(ec);

        }

        continue;

      }

      ec = exception_cache();

      if (ec != NULL) {

        new_entry->set_next(ec);

      }

    }

    if (Atomic::cmpxchg(new_entry, &_exception_cache, ec) == ec) {

      return;

    }

  }

}

void CompiledMethod::clean_exception_cache() {

  // For each nmethod, only a single thread may call this cleanup function

  // at the same time, whether called in STW cleanup or concurrent cleanup.

  // Note that if the GC is processing exception cache cleaning in a concurrent phase,

  // then a single writer may contend with cleaning up the head pointer to the

  // first ExceptionCache node that has a Klass* that is alive. That is fine,

  // as long as there is no concurrent cleanup of next pointers from concurrent writers.

  // And the concurrent writers do not clean up next pointers, only the head.

  // Also note that concurent readers will walk through Klass* pointers that are not

  // alive. That does not cause ABA problems, because Klass* is deleted after

  // a handshake with all threads, after all stale ExceptionCaches have been

  // unlinked. That is also when the CodeCache::exception_cache_purge_list()

  // is deleted, with all ExceptionCache entries that were cleaned concurrently.

  // That similarly implies that CAS operations on ExceptionCache entries do not

  // suffer from ABA problems as unlinking and deletion is separated by a global

  // handshake operation.

  ExceptionCache* prev = NULL;

  ExceptionCache* curr = exception_cache_acquire();

  while (curr != NULL) {

    ExceptionCache* next = curr->next();

    if (!curr->exception_type()->is_loader_alive()) {

      if (prev == NULL) {

        // Try to clean head; this is contended by concurrent inserts, that

        // both lazily clean the head, and insert entries at the head. If

        // the CAS fails, the operation is restarted.

        if (Atomic::cmpxchg(next, &_exception_cache, curr) != curr) {

          prev = NULL;

          curr = exception_cache_acquire();

          continue;

        }

      } else {

        // It is impossible to during cleanup connect the next pointer to

        // an ExceptionCache that has not been published before a safepoint

        // prior to the cleanup. Therefore, release is not required.

        prev->set_next(next);

      }

      // prev stays the same.

      CodeCache::release_exception_cache(curr);

    } else {

      prev = curr;

    }

    curr = next;

  }

}

// public method for accessing the exception cache

// These are the public access methods.

address CompiledMethod::handler_for_exception_and_pc(Handle exception, address pc) {

  // We never grab a lock to read the exception cache, so we may

  // have false negatives. This is okay, as it can only happen during

  // the first few exception lookups for a given nmethod.

  ExceptionCache* ec = exception_cache_acquire();

  while (ec != NULL) {

    address ret_val;

    if ((ret_val = ec->match(exception,pc)) != NULL) {

      return ret_val;

    }

    ec = ec->next();

  }

  return NULL;

}

void CompiledMethod::add_handler_for_exception_and_pc(Handle exception, address pc, address handler) {

  // There are potential race conditions during exception cache updates, so we

  // must own the ExceptionCache_lock before doing ANY modifications. Because

  // we don't lock during reads, it is possible to have several threads attempt

  // to update the cache with the same data. We need to check for already inserted

  // copies of the current data before adding it.

  MutexLocker ml(ExceptionCache_lock);

  ExceptionCache* target_entry = exception_cache_entry_for_exception(exception);

  if (target_entry == NULL || !target_entry->add_address_and_handler(pc,handler)) {

    target_entry = new ExceptionCache(exception,pc,handler);

    add_exception_cache_entry(target_entry);

  }

}

// private method for handling exception cache

// These methods are private, and used to manipulate the exception cache

// directly.

ExceptionCache* CompiledMethod::exception_cache_entry_for_exception(Handle exception) {

  ExceptionCache* ec = exception_cache_acquire();

  while (ec != NULL) {

    if (ec->match_exception_with_space(exception)) {

      return ec;

    }

    ec = ec->next();

  }

  return NULL;

}

//-------------end of code for ExceptionCache--------------

bool CompiledMethod::is_at_poll_return(address pc) {

  RelocIterator iter(this, pc, pc+1);

  while (iter.next()) {

    if (iter.type() == relocInfo::poll_return_type)

      return true;

  }

  return false;

}

bool CompiledMethod::is_at_poll_or_poll_return(address pc) {

  RelocIterator iter(this, pc, pc+1);

  while (iter.next()) {

    relocInfo::relocType t = iter.type();

    if (t == relocInfo::poll_return_type || t == relocInfo::poll_type)

      return true;

  }

  return false;

}

void CompiledMethod::verify_oop_relocations() {

  // Ensure sure that the code matches the current oop values

  RelocIterator iter(this, NULL, NULL);

  while (iter.next()) {

    if (iter.type() == relocInfo::oop_type) {

      oop_Relocation* reloc = iter.oop_reloc();

      if (!reloc->oop_is_immediate()) {

        reloc->verify_oop_relocation();

      }

    }

  }

}

ScopeDesc* CompiledMethod::scope_desc_at(address pc) {

  PcDesc* pd = pc_desc_at(pc);

  guarantee(pd != NULL, "scope must be present");

  return new ScopeDesc(this, pd->scope_decode_offset(),

                       pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),

                       pd->return_oop());

}

ScopeDesc* CompiledMethod::scope_desc_near(address pc) {

  PcDesc* pd = pc_desc_near(pc);

  guarantee(pd != NULL, "scope must be present");

  return new ScopeDesc(this, pd->scope_decode_offset(),

                       pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),

                       pd->return_oop());

}

address CompiledMethod::oops_reloc_begin() const {

  // If the method is not entrant or zombie then a JMP is plastered over the

  // first few bytes.  If an oop in the old code was there, that oop

  // should not get GC'd.  Skip the first few bytes of oops on

  // not-entrant methods.

  if (frame_complete_offset() != CodeOffsets::frame_never_safe &&

      code_begin() + frame_complete_offset() >

      verified_entry_point() + NativeJump::instruction_size)

  {

    // If we have a frame_complete_offset after the native jump, then there

    // is no point trying to look for oops before that. This is a requirement

    // for being allowed to scan oops concurrently.

    return code_begin() + frame_complete_offset();

  }

  // It is not safe to read oops concurrently using entry barriers, if their

  // location depend on whether the nmethod is entrant or not.

  assert(BarrierSet::barrier_set()->barrier_set_nmethod() == NULL, "Not safe oop scan");

  address low_boundary = verified_entry_point();

  if (!is_in_use() && is_nmethod()) {

    low_boundary += NativeJump::instruction_size;

    // %%% Note:  On SPARC we patch only a 4-byte trap, not a full NativeJump.

    // This means that the low_boundary is going to be a little too high.

    // This shouldn't matter, since oops of non-entrant methods are never used.

    // In fact, why are we bothering to look at oops in a non-entrant method??

  }

  return low_boundary;

}

int CompiledMethod::verify_icholder_relocations() {

  ResourceMark rm;

  int count = 0;

  RelocIterator iter(this);

  while(iter.next()) {

    if (iter.type() == relocInfo::virtual_call_type) {

      if (CompiledIC::is_icholder_call_site(iter.virtual_call_reloc(), this)) {

        CompiledIC *ic = CompiledIC_at(&iter);

        if (TraceCompiledIC) {

          tty->print("noticed icholder " INTPTR_FORMAT " ", p2i(ic->cached_icholder()));

          ic->print();

        }

        assert(ic->cached_icholder() != NULL, "must be non-NULL");

        count++;

      }

    }

  }

  return count;

}

// Method that knows how to preserve outgoing arguments at call. This method must be

// called with a frame corresponding to a Java invoke

void CompiledMethod::preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map, OopClosure* f) {

  if (method() != NULL && !method()->is_native()) {

    address pc = fr.pc();

    SimpleScopeDesc ssd(this, pc);

    Bytecode_invoke call(ssd.method(), ssd.bci());

    bool has_receiver = call.has_receiver();

    bool has_appendix = call.has_appendix();

    Symbol* signature = call.signature();

    // The method attached by JIT-compilers should be used, if present.

    // Bytecode can be inaccurate in such case.

    Method* callee = attached_method_before_pc(pc);

    if (callee != NULL) {

      has_receiver = !(callee->access_flags().is_static());

      has_appendix = false;

      signature = callee->signature();

    }

    fr.oops_compiled_arguments_do(signature, has_receiver, has_appendix, reg_map, f);

  }

}

Method* CompiledMethod::attached_method(address call_instr) {

  assert(code_contains(call_instr), "not part of the nmethod");

  RelocIterator iter(this, call_instr, call_instr + 1);

  while (iter.next()) {

    if (iter.addr() == call_instr) {

      switch(iter.type()) {

        case relocInfo::static_call_type:      return iter.static_call_reloc()->method_value();

        case relocInfo::opt_virtual_call_type: return iter.opt_virtual_call_reloc()->method_value();

        case relocInfo::virtual_call_type:     return iter.virtual_call_reloc()->method_value();

        default:                               break;

      }

    }

  }

  return NULL; // not found

}

Method* CompiledMethod::attached_method_before_pc(address pc) {

  if (NativeCall::is_call_before(pc)) {

    NativeCall* ncall = nativeCall_before(pc);

    return attached_method(ncall->instruction_address());

  }

  return NULL; // not a call

}

void CompiledMethod::clear_inline_caches() {

  assert(SafepointSynchronize::is_at_safepoint(), "cleaning of IC's only allowed at safepoint");

  if (is_zombie()) {

    return;

  }

  RelocIterator iter(this);

  while (iter.next()) {

    iter.reloc()->clear_inline_cache();

  }

}

// Clear IC callsites, releasing ICStubs of all compiled ICs

// as well as any associated CompiledICHolders.

void CompiledMethod::clear_ic_callsites() {

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

  ResourceMark rm;

  RelocIterator iter(this);

  while(iter.next()) {

    if (iter.type() == relocInfo::virtual_call_type) {

      CompiledIC* ic = CompiledIC_at(&iter);

      ic->set_to_clean(false);

    }

  }

}

#ifdef ASSERT

// Check class_loader is alive for this bit of metadata.

class CheckClass : public MetadataClosure {

  void do_metadata(Metadata* md) {

    Klass* klass = NULL;

    if (md->is_klass()) {

      klass = ((Klass*)md);

    } else if (md->is_method()) {

      klass = ((Method*)md)->method_holder();

    } else if (md->is_methodData()) {

      klass = ((MethodData*)md)->method()->method_holder();

    } else {

      md->print();

      ShouldNotReachHere();

    }

    assert(klass->is_loader_alive(), "must be alive");

  }

};

#endif // ASSERT

bool CompiledMethod::clean_ic_if_metadata_is_dead(CompiledIC *ic) {

  if (ic->is_clean()) {

    return true;

  }

  if (ic->is_icholder_call()) {

    // The only exception is compiledICHolder metdata which may

    // yet be marked below. (We check this further below).

    CompiledICHolder* cichk_metdata = ic->cached_icholder();

    if (cichk_metdata->is_loader_alive()) {

      return true;

    }

  } else {

    Metadata* ic_metdata = ic->cached_metadata();

    if (ic_metdata != NULL) {

      if (ic_metdata->is_klass()) {

        if (((Klass*)ic_metdata)->is_loader_alive()) {

          return true;

        }

      } else if (ic_metdata->is_method()) {

        Method* method = (Method*)ic_metdata;

        assert(!method->is_old(), "old method should have been cleaned");

        if (method->method_holder()->is_loader_alive()) {

          return true;

        }

      } else {

        ShouldNotReachHere();

      }

    }

  }

  return ic->set_to_clean();

}

// Clean references to unloaded nmethods at addr from this one, which is not unloaded.

template <class CompiledICorStaticCall>

static bool clean_if_nmethod_is_unloaded(CompiledICorStaticCall *ic, address addr, CompiledMethod* from,

                                         bool clean_all) {

  // Ok, to lookup references to zombies here

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

  CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;

  if (nm != NULL) {

    // Clean inline caches pointing to both zombie and not_entrant methods

    if (clean_all || !nm->is_in_use() || nm->is_unloading() || (nm->method()->code() != nm)) {

      if (!ic->set_to_clean(from->is_alive())) {

        return false;

      }

      assert(ic->is_clean(), "nmethod " PTR_FORMAT "not clean %s", p2i(from), from->method()->name_and_sig_as_C_string());

    }

  }

  return true;

}

static bool clean_if_nmethod_is_unloaded(CompiledIC *ic, CompiledMethod* from,

                                         bool clean_all) {

  return clean_if_nmethod_is_unloaded(ic, ic->ic_destination(), from, clean_all);

}

static bool clean_if_nmethod_is_unloaded(CompiledStaticCall *csc, CompiledMethod* from,

                                         bool clean_all) {

  return clean_if_nmethod_is_unloaded(csc, csc->destination(), from, clean_all);

}

// Cleans caches in nmethods that point to either classes that are unloaded

// or nmethods that are unloaded.

//

// Can be called either in parallel by G1 currently or after all

// nmethods are unloaded.  Return postponed=true in the parallel case for

// inline caches found that point to nmethods that are not yet visited during

// the do_unloading walk.

bool CompiledMethod::unload_nmethod_caches(bool unloading_occurred) {

  ResourceMark rm;