CodeCache.java

/*
 * Copyright (c) 2000, 2020, 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
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 * questions.
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package sun.jvm.hotspot.code;

import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.types.*;
import sun.jvm.hotspot.utilities.*;
import sun.jvm.hotspot.utilities.Observable;
import sun.jvm.hotspot.utilities.Observer;

public class CodeCache {
  private static GrowableArray<CodeHeap> heapArray;
  private static VirtualConstructor virtualConstructor;

  static {
    VM.registerVMInitializedObserver(new Observer() {
        public void update(Observable o, Object data) {
          initialize(VM.getVM().getTypeDataBase());
        }
      });
  }

  private static synchronized void initialize(TypeDataBase db) {
    Type type = db.lookupType("CodeCache");

    // Get array of CodeHeaps
    // Note: CodeHeap may be subclassed with optional private heap mechanisms.
    Type codeHeapType = db.lookupType("CodeHeap");
    VirtualBaseConstructor<CodeHeap> heapConstructor =
        new VirtualBaseConstructor<>(db, codeHeapType, "sun.jvm.hotspot.memory", CodeHeap.class);

    AddressField heapsField = type.getAddressField("_heaps");
    heapArray = GrowableArray.create(heapsField.getValue(), heapConstructor);

    virtualConstructor = new VirtualConstructor(db);
    // Add mappings for all possible CodeBlob subclasses
    virtualConstructor.addMapping("BufferBlob", BufferBlob.class);
    virtualConstructor.addMapping("nmethod", NMethod.class);
    virtualConstructor.addMapping("RuntimeStub", RuntimeStub.class);
    virtualConstructor.addMapping("AdapterBlob", AdapterBlob.class);
    virtualConstructor.addMapping("MethodHandlesAdapterBlob", MethodHandlesAdapterBlob.class);
    virtualConstructor.addMapping("VtableBlob", VtableBlob.class);
    virtualConstructor.addMapping("SafepointBlob", SafepointBlob.class);
    virtualConstructor.addMapping("DeoptimizationBlob", DeoptimizationBlob.class);
    if (VM.getVM().isServerCompiler()) {
      virtualConstructor.addMapping("ExceptionBlob", ExceptionBlob.class);
      virtualConstructor.addMapping("UncommonTrapBlob", UncommonTrapBlob.class);
    }
  }

  public boolean contains(Address p) {
    for (int i = 0; i < heapArray.length(); ++i) {
      if (heapArray.at(i).contains(p)) {
        return true;
      }
    }
    return false;
  }

  /** When VM.getVM().isDebugging() returns true, this behaves like
      findBlobUnsafe */
  public CodeBlob findBlob(Address start) {
    CodeBlob result = findBlobUnsafe(start);
    if (result == null) return null;
    if (VM.getVM().isDebugging()) {
      return result;
    }
    // We could potientially look up non_entrant methods
    // NOTE: this is effectively a "guarantee", and is slightly different from the one in the VM
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(!(result.isZombie() || result.isLockedByVM()), "unsafe access to zombie method");
    }
    return result;
  }

  public CodeBlob findBlobUnsafe(Address start) {
    CodeBlob result = null;
    CodeHeap containing_heap = null;
    for (int i = 0; i < heapArray.length(); ++i) {
      if (heapArray.at(i).contains(start)) {
        containing_heap = heapArray.at(i);
        break;
      }
    }
    if (containing_heap == null) {
      return null;
    }

    try {
      result = (CodeBlob) virtualConstructor.instantiateWrapperFor(containing_heap.findStart(start));
    }
    catch (WrongTypeException wte) {
      Address cbAddr = null;
      try {
        cbAddr = containing_heap.findStart(start);
      }
      catch (Exception findEx) {
        findEx.printStackTrace();
      }

      String message = "Couldn't deduce type of CodeBlob ";
      if (cbAddr != null) {
        message = message + "@" + cbAddr + " ";
      }
      message = message + "for PC=" + start;

      throw new RuntimeException(message, wte);
    }
    if (result == null) return null;
    if (Assert.ASSERTS_ENABLED) {
      // The pointer to the HeapBlock that contains this blob is outside of the blob,
      // but it shouldn't be an error to find a blob based on the pointer to the HeapBlock.
      // The heap block header is padded out to an 8-byte boundary. See heap.hpp. The
      // simplest way to compute the header size is just 2 * addressSize.
      Assert.that(result.blobContains(start) ||
                  result.blobContains(start.addOffsetTo(2 * VM.getVM().getAddressSize())),
                  "found wrong CodeBlob");
    }
    return result;
  }

  public NMethod findNMethod(Address start) {
    CodeBlob cb = findBlob(start);
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(cb == null || cb.isNMethod(), "did not find an nmethod");
    }
    return (NMethod) cb;
  }

  public NMethod findNMethodUnsafe(Address start) {
    CodeBlob cb = findBlobUnsafe(start);
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(cb == null || cb.isNMethod(), "did not find an nmethod");
    }
    return (NMethod) cb;
  }

  /** Routine for instantiating appropriately-typed wrapper for a
      CodeBlob. Used by CodeCache, Runtime1, etc. */
  public CodeBlob createCodeBlobWrapper(Address codeBlobAddr) {
    try {
      return (CodeBlob) virtualConstructor.instantiateWrapperFor(codeBlobAddr);
    }
    catch (Exception e) {
      String message = "Unable to deduce type of CodeBlob from address " + codeBlobAddr +
                       " (expected type nmethod, RuntimeStub, VtableBlob, ";
      if (VM.getVM().isClientCompiler()) {
        message = message + " or ";
      }
      message = message + "SafepointBlob";
      if (VM.getVM().isServerCompiler()) {
        message = message + ", DeoptimizationBlob, or ExceptionBlob";
      }
      message = message + ")";
      throw new RuntimeException(message);
    }
  }

  public void iterate(CodeCacheVisitor visitor) {
    visitor.prologue(lowBound(), highBound());
    for (int i = 0; i < heapArray.length(); ++i) {
      CodeHeap current_heap = heapArray.at(i);
      current_heap.iterate(visitor, this);
    }
    visitor.epilogue();
  }

  //--------------------------------------------------------------------------------
  // Internals only below this point
  //

  private Address lowBound() {
    Address low = heapArray.at(0).begin();
    for (int i = 1; i < heapArray.length(); ++i) {
      if (heapArray.at(i).begin().lessThan(low)) {
        low = heapArray.at(i).begin();
      }
    }
    return low;
  }

  private Address highBound() {
    Address high = heapArray.at(0).end();
    for (int i = 1; i < heapArray.length(); ++i) {
      if (heapArray.at(i).end().greaterThan(high)) {
        high = heapArray.at(i).end();
      }
    }
    return high;
  }
}