/*

 * Copyright (c) 2015, 2016, 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/scopeDesc.hpp"

#include "code/codeCache.hpp"

#include "prims/methodHandles.hpp"

#include "interpreter/bytecode.hpp"

#include "memory/resourceArea.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),

  _method(method), _mark_for_deoptimization_status(not_marked) {

  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),

  _method(method), _mark_for_deoptimization_status(not_marked) {

  init_defaults();

}

void CompiledMethod::init_defaults() {

  _has_unsafe_access          = 0;

  _has_method_handle_invokes  = 0;

  _lazy_critical_native       = 0;

  _has_wide_vectors           = 0;

  _unloading_clock            = 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 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;

  }

}

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

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");

  ExceptionCache *ec = exception_cache();

  if (ec != NULL) {

    new_entry->set_next(ec);

  }

  release_set_exception_cache(new_entry);

}

void CompiledMethod::clean_exception_cache(BoolObjectClosure* is_alive) {

  ExceptionCache* prev = NULL;

  ExceptionCache* curr = exception_cache();

  while (curr != NULL) {

    ExceptionCache* next = curr->next();

    Klass* ex_klass = curr->exception_type();

    if (ex_klass != NULL && !ex_klass->is_loader_alive(is_alive)) {

      if (prev == NULL) {

        set_exception_cache(next);

      } else {

        prev->set_next(next);

      }

      delete curr;

      // prev stays the same.

    } 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();

  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);

  }

}

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

// 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();

  while (ec != NULL) {

    if (ec->match_exception_with_space(exception)) {

      return ec;

    }

    ec = ec->next();

  }

  return NULL;

}

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());

}

void CompiledMethod::cleanup_inline_caches(bool clean_all/*=false*/) {

  assert_locked_or_safepoint(CompiledIC_lock);

  // 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.

  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??

  }

  // Find all calls in an nmethod and clear the ones that point to non-entrant,

  // zombie and unloaded nmethods.

  ResourceMark rm;

  RelocIterator iter(this, low_boundary);

  while(iter.next()) {

    switch(iter.type()) {

      case relocInfo::virtual_call_type:

      case relocInfo::opt_virtual_call_type: {

        CompiledIC *ic = CompiledIC_at(&iter);

        // Ok, to lookup references to zombies here

        CodeBlob *cb = CodeCache::find_blob_unsafe(ic->ic_destination());

        if( cb != NULL && cb->is_compiled() ) {

          CompiledMethod* nm = cb->as_compiled_method();

          // Clean inline caches pointing to zombie, non-entrant and unloaded methods

          if (clean_all || !nm->is_in_use() || (nm->method()->code() != nm)) ic->set_to_clean(is_alive());

        }

        break;

      }

      case relocInfo::static_call_type: {

          CompiledStaticCall *csc = compiledStaticCall_at(iter.reloc());

          CodeBlob *cb = CodeCache::find_blob_unsafe(csc->destination());

          if( cb != NULL && cb->is_compiled() ) {

            CompiledMethod* cm = cb->as_compiled_method();

            // Clean inline caches pointing to zombie, non-entrant and unloaded methods

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

              csc->set_to_clean();

            }

          }

        break;

      }

    }

  }

}

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) {

#ifndef SHARK

  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);

  }

#endif // !SHARK

}

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();

      }

    }

  }

  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 ICStubs of all compiled ICs

void CompiledMethod::clear_ic_stubs() {

  assert_locked_or_safepoint(CompiledIC_lock);

  RelocIterator iter(this);

  while(iter.next()) {

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

      CompiledIC* ic = CompiledIC_at(&iter);

      ic->clear_ic_stub();

    }

  }

}

#ifdef ASSERT

class CheckClass : AllStatic {

  static BoolObjectClosure* _is_alive;

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

  static void check_class(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(_is_alive), "must be alive");

  }

 public:

  static void do_check_class(BoolObjectClosure* is_alive, CompiledMethod* nm) {

    assert(SafepointSynchronize::is_at_safepoint(), "this is only ok at safepoint");

    _is_alive = is_alive;

    nm->metadata_do(check_class);

  }

};

// This is called during a safepoint so can use static data

BoolObjectClosure* CheckClass::_is_alive = NULL;

#endif // ASSERT

void CompiledMethod::clean_ic_if_metadata_is_dead(CompiledIC *ic, BoolObjectClosure *is_alive) {

  if (ic->is_icholder_call()) {

    // The only exception is compiledICHolder oops which may

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

    CompiledICHolder* cichk_oop = ic->cached_icholder();

    if (cichk_oop->holder_method()->method_holder()->is_loader_alive(is_alive) &&

        cichk_oop->holder_klass()->is_loader_alive(is_alive)) {

      return;

    }

  } else {

    Metadata* ic_oop = ic->cached_metadata();

    if (ic_oop != NULL) {

      if (ic_oop->is_klass()) {

        if (((Klass*)ic_oop)->is_loader_alive(is_alive)) {

          return;

        }

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

        if (((Method*)ic_oop)->method_holder()->is_loader_alive(is_alive)) {

          return;

        }

      } else {

        ShouldNotReachHere();

      }

    }

  }

  ic->set_to_clean();

}

unsigned char CompiledMethod::_global_unloading_clock = 0;

void CompiledMethod::increase_unloading_clock() {

  _global_unloading_clock++;

  if (_global_unloading_clock == 0) {

    // _nmethods are allocated with _unloading_clock == 0,

    // so 0 is never used as a clock value.

    _global_unloading_clock = 1;

  }

}

void CompiledMethod::set_unloading_clock(unsigned char unloading_clock) {

  OrderAccess::release_store((volatile jubyte*)&_unloading_clock, unloading_clock);

}

unsigned char CompiledMethod::unloading_clock() {

  return (unsigned char)OrderAccess::load_acquire((volatile jubyte*)&_unloading_clock);

}

// Processing of oop references should have been sufficient to keep

// all strong references alive.  Any weak references should have been

// cleared as well.  Visit all the metadata and ensure that it's

// really alive.

void CompiledMethod::verify_metadata_loaders(address low_boundary, BoolObjectClosure* is_alive) {

#ifdef ASSERT

    RelocIterator iter(this, low_boundary);

    while (iter.next()) {

    // static_stub_Relocations may have dangling references to

    // Method*s so trim them out here.  Otherwise it looks like

    // compiled code is maintaining a link to dead metadata.

    address static_call_addr = NULL;

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

      CompiledIC* cic = CompiledIC_at(&iter);

      if (!cic->is_call_to_interpreted()) {

        static_call_addr = iter.addr();

      }

    } else if (iter.type() == relocInfo::static_call_type) {

      CompiledStaticCall* csc = compiledStaticCall_at(iter.reloc());

      if (!csc->is_call_to_interpreted()) {

        static_call_addr = iter.addr();

      }

    }

    if (static_call_addr != NULL) {

      RelocIterator sciter(this, low_boundary);

      while (sciter.next()) {

        if (sciter.type() == relocInfo::static_stub_type &&

            sciter.static_stub_reloc()->static_call() == static_call_addr) {

          sciter.static_stub_reloc()->clear_inline_cache();

        }

      }

    }

  }

  // Check that the metadata embedded in the nmethod is alive

  CheckClass::do_check_class(is_alive, this);

#endif

}

// This is called at the end of the strong tracing/marking phase of a

// GC to unload an nmethod if it contains otherwise unreachable

// oops.

void CompiledMethod::do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred) {

  // Make sure the oop's ready to receive visitors

  assert(!is_zombie() && !is_unloaded(),

         "should not call follow on zombie or unloaded nmethod");

  // If the method is not entrant 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.

  address low_boundary = verified_entry_point();

  if (is_not_entrant()) {

    low_boundary += NativeJump::instruction_size;

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

    // (See comment above.)

  }

  // The RedefineClasses() API can cause the class unloading invariant

  // to no longer be true. See jvmtiExport.hpp for details.

  // Also, leave a debugging breadcrumb in local flag.

  if (JvmtiExport::has_redefined_a_class()) {

    // This set of the unloading_occurred flag is done before the

    // call to post_compiled_method_unload() so that the unloading

    // of this nmethod is reported.

    unloading_occurred = true;

  }

  // Exception cache

  clean_exception_cache(is_alive);

  // If class unloading occurred we first iterate over all inline caches and

  // clear ICs where the cached oop is referring to an unloaded klass or method.

  // The remaining live cached oops will be traversed in the relocInfo::oop_type

  // iteration below.

  if (unloading_occurred) {

    RelocIterator iter(this, low_boundary);

    while(iter.next()) {

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

        CompiledIC *ic = CompiledIC_at(&iter);

        clean_ic_if_metadata_is_dead(ic, is_alive);

      }

    }

  }

  if (do_unloading_oops(low_boundary, is_alive, unloading_occurred)) {

    return;

  }