CompiledVFrame.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
 *
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package sun.jvm.hotspot.runtime;

import java.util.*;
import sun.jvm.hotspot.code.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.utilities.*;

/** FIXME: missing many accessors; all we have right now is the method
    and BCI. NOTE that this has been modified from the VM's version to
    handle NULL ScopeDescs for the debugging case. This simplifies
    using code a great deal. */

public class CompiledVFrame extends JavaVFrame {
  private ScopeDesc scope;
  private boolean mayBeImprecise;

  public CompiledVFrame(Frame fr, RegisterMap regMap, JavaThread thread, ScopeDesc scope, boolean mayBeImprecise) {
    super(fr, regMap, thread);
    this.scope = scope;
    this.mayBeImprecise = mayBeImprecise;
    if (!VM.getVM().isDebugging()) {
      Assert.that(scope != null, "scope must be present");
    }
  }

  public boolean isTop() {
    if (VM.getVM().isDebugging()) {
      return (getScope() == null || getScope().isTop());
    } else {
      return getScope().isTop();
    }
  }

  public boolean isCompiledFrame() {
    return true;
  }

  public boolean isDeoptimized() {
    return fr.isDeoptimized();
  }

  public boolean mayBeImpreciseDbg() {
    return mayBeImprecise;
  }

  /** Returns the active method */
  public NMethod getCode() {
    return VM.getVM().getCodeCache().findNMethod(fr.getPC());
  }

  /** Returns the active method. Does not perform a guarantee
      regarding unloaded methods -- more suitable for debugging
      system. */
  public NMethod getCodeUnsafe() {
    return VM.getVM().getCodeCache().findNMethodUnsafe(fr.getPC());
  }

  /** Returns the ScopeDesc */
  public ScopeDesc getScope() {
    return scope;
  }

  public Method getMethod() {
    if (VM.getVM().isDebugging() && getScope() == null) {
      return getCodeUnsafe().getMethod();
    }
    return getScope().getMethod();
  }

  public StackValueCollection getLocals() {
    if (getScope() == null)
      return new StackValueCollection();
    List<ScopeValue> scvList = getScope().getLocals();
    if (scvList == null)
      return new StackValueCollection();

    // scvList is the list of ScopeValues describing the JVM stack state.
    // There is one scv_list entry for every JVM stack state in use.
    int length = scvList.size();
    StackValueCollection result = new StackValueCollection(length);
    for( int i = 0; i < length; i++ )
      result.add( createStackValue(scvList.get(i)) );

    return result;
  }

  public StackValueCollection getExpressions() {
    if (getScope() == null)
      return new StackValueCollection();
    List<ScopeValue> scvList = getScope().getExpressions();
    if (scvList == null)
      return new StackValueCollection();

    // scvList is the list of ScopeValues describing the JVM stack state.
    // There is one scv_list entry for every JVM stack state in use.
    int length = scvList.size();
    StackValueCollection result = new StackValueCollection(length);
    for( int i = 0; i < length; i++ )
      result.add( createStackValue(scvList.get(i)) );

    return result;
  }

  public List<MonitorInfo> getMonitors() {
    if (getScope() == null) {
      return new ArrayList<>();
    }
    List<MonitorValue> monitors = getScope().getMonitors();
    if (monitors == null) {
      return new ArrayList<>();
    }
    List<MonitorInfo> result = new ArrayList<>(monitors.size());
    for (int i = 0; i < monitors.size(); i++) {
      MonitorValue mv = monitors.get(i);
      ScopeValue ov = mv.owner();
      StackValue ownerSV = createStackValue(ov); // it is an oop
      if (ov.isObject()) { // The owner object was scalar replaced
        Assert.that(mv.eliminated() && ownerSV.objIsScalarReplaced(), "monitor should be eliminated for scalar replaced object");
        // Put klass for scalar replaced object.
        ScopeValue kv = ((ObjectValue)ov).getKlass();
        Assert.that(kv.isConstantOop(), "klass should be oop constant for scalar replaced object");
        OopHandle k = ((ConstantOopReadValue)kv).getValue();
        result.add(new MonitorInfo(k, resolveMonitorLock(mv.basicLock()), mv.eliminated(), true));
      } else {
        result.add(new MonitorInfo(ownerSV.getObject(), resolveMonitorLock(mv.basicLock()), mv.eliminated(), false));
      }
    }
    return result;
  }

  public int getBCI() {
    int raw = getRawBCI();
    return ((raw == DebugInformationRecorder.SYNCHRONIZATION_ENTRY_BCI) ? 0 : raw);
  }

  /** Returns SynchronizationEntryBCI or bci() (used for synchronization) */
  public int getRawBCI() {
    if (VM.getVM().isDebugging() && getScope() == null) {
      return 0; // No debugging information!
    }
    return getScope().getBCI();
  }

  /** Returns the sender vframe */
  public VFrame sender() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(isTop(), "just checking");
    }
    return sender(false);
  }

  public VFrame sender(boolean mayBeImprecise) {
    if (!VM.getVM().isDebugging()) {
      if (Assert.ASSERTS_ENABLED) {
        Assert.that(scope != null, "When new stub generator is in place, then scope can never be NULL");
      }
    }
    Frame f = (Frame) getFrame().clone();
    return (isTop()
              ? super.sender(false)
              : new CompiledVFrame(f, getRegisterMap(), getThread(), getScope().sender(), mayBeImprecise));
  }

  private StackValue createStackValue(ScopeValue sv) {
    // FIXME: this code appears to be out-of-date with respect to the VM especially in 64-bit mode
    if (sv.isLocation()) {
      // Stack or register value
      Location loc = ((LocationValue) sv).getLocation();

      if (loc.isIllegal()) return new StackValue();

      // First find address of value
      Address valueAddr = loc.isRegister()
        // Value was in a callee-save register
        ? getRegisterMap().getLocation(new VMReg(loc.getRegisterNumber()))
        // Else value was directly saved on the stack. The frame's original stack pointer,
        // before any extension by its callee (due to Compiler1 linkage on SPARC), must be used.
        : ((Address)fr.getUnextendedSP()).addOffsetTo(loc.getStackOffset());

      // Then package it right depending on type
      if (loc.holdsFloat()) {    // Holds a float in a double register?
        // The callee has no clue whether the register holds a float,
        // double or is unused.  He always saves a double.  Here we know
        // a double was saved, but we only want a float back.  Narrow the
        // saved double to the float that the JVM wants.
        if (Assert.ASSERTS_ENABLED) {
          Assert.that( loc.isRegister(), "floats always saved to stack in 1 word" );
        }
        float value = (float) valueAddr.getJDoubleAt(0);
        return new StackValue(Float.floatToIntBits(value) & 0xFFFFFFFF); // 64-bit high half is stack junk
      } else if (loc.holdsInt()) {  // Holds an int in a long register?
        // The callee has no clue whether the register holds an int,
        // long or is unused.  He always saves a long.  Here we know
        // a long was saved, but we only want an int back.  Narrow the
        // saved long to the int that the JVM wants.
        if (Assert.ASSERTS_ENABLED) {
          Assert.that( loc.isRegister(), "ints always saved to stack in 1 word" );
        }
        return new StackValue(valueAddr.getJLongAt(0) & 0xFFFFFFFF);
      } else if (loc.holdsNarrowOop()) {  // Holds an narrow oop?
        if (loc.isRegister() && VM.getVM().isBigEndian()) {
          // The callee has no clue whether the register holds an narrow oop,
          // long or is unused.  He always saves a long.  Here we know
          // a long was saved, but we only want an narrow oop back.  Narrow the
          // saved long to the narrow oop that the JVM wants.
          return new StackValue(valueAddr.getCompOopHandleAt(VM.getVM().getIntSize()), 0);
        } else {
          return new StackValue(valueAddr.getCompOopHandleAt(0), 0);
        }
      } else if( loc.holdsOop() ) {  // Holds an oop?
        return new StackValue(valueAddr.getOopHandleAt(0), 0);
      } else if( loc.holdsDouble() ) {
        // Double value in a single stack slot
        return new StackValue(valueAddr.getJIntAt(0) & 0xFFFFFFFF);
      } else if(loc.holdsAddr()) {
        if (Assert.ASSERTS_ENABLED) {
          Assert.that(!VM.getVM().isServerCompiler(), "No address type for locations with C2 (jsr-s are inlined)");
        }
        // FIXME: not yet implemented (no access to safepoint state yet)
        return new StackValue(0);
        //      intptr_t return_addr_tmp = *(intptr_t *)value_addr;
        //      int bci = -1;
        //      // Get the bci of the jsr that generated this returnAddress value.
        //      // If the destination of a jsr is a block that ends with a return or throw, then
        //      // the GraphBuilder converts the jsr into a direct goto.  This has the side effect that
        //      // the return address for the jsr gets emitted as a bci instead of as a real pc
        //      if (code()->contains((address)return_addr_tmp)) {
        //        ScopeDesc* scope = code()->scope_desc_at((address)(return_addr_tmp - jsr_call_offset), false);
        //        bci = scope->bci();
        //      } else {
        //        bci = (int)return_addr_tmp;
        //      }
        //      // no need to lock method as this happens at Safepoint
        //      assert (SafepointSynchronize::is_at_safepoint(), "must be at safepoint, otherwise lock method()");
        //      // make sure bci points to jsr
        //      Bytecode* bytecode = Bytecode_at(method()->bcp_from(bci));
        //      Bytecodes::Code bc = bytecode->code();
        //      assert (bc == Bytecodes::_jsr || bc == Bytecodes::_jsr_w, "must be jsr");
        //
        //      // the real returnAddress is the bytecode following the jsr
        //      return new StackValue((intptr_t)(bci + Bytecodes::length_for(bc)));
      } else if (VM.getVM().isLP64() && loc.holdsLong()) {
        if ( loc.isRegister() ) {
          // Long value in two registers, high half in the first, low in the second
          return new StackValue(((valueAddr.getJLongAt(0) & 0xFFFFFFFF) << 32) |
                                ((valueAddr.getJLongAt(8) & 0xFFFFFFFF)));
        } else {
          // Long value in a single stack slot
          return new StackValue(valueAddr.getJLongAt(0));
        }
      } else if( loc.isRegister() ) {
        // At the moment, all non-oop values in registers are 4 bytes,
        // including double and long halves (see Compile::FillLocArray() in
        // opto/output.cpp).  Haul them out as such and return a StackValue
        // containing an image of the value as it appears in a stack slot.
        // If this is a double or long half, the interpreter _must_ deal
        // with doubles and longs as entities split across two stack slots.
        // To change this so doubles and/or longs can live in one stack slot,
        // a StackValue will have to understand that it can contain an
        // undivided double or long, implying that a Location (and the debug
        // info mechanism) and FillLocArray() will also have to understand it.
        return new StackValue(valueAddr.getJIntAt(0) & 0xFFFFFFFF);
      } else {
        return new StackValue(valueAddr.getJIntAt(0) & 0xFFFFFFFF);
      }
    } else if (sv.isConstantInt()) {
      // Constant int: treat same as register int.
      return new StackValue(((ConstantIntValue) sv).getValue() & 0xFFFFFFFF);
    } else if (sv.isConstantOop()) {
      // constant oop
      return new StackValue(((ConstantOopReadValue) sv).getValue(), 0);
    } else if (sv.isConstantDouble()) {
      // Constant double in a single stack slot
      double d = ((ConstantDoubleValue) sv).getValue();
      return new StackValue(Double.doubleToLongBits(d) & 0xFFFFFFFF);
    } else if (VM.getVM().isLP64() && sv.isConstantLong()) {
      // Constant long in a single stack slot
      return new StackValue(((ConstantLongValue) sv).getValue() & 0xFFFFFFFF);
    } else if (sv.isObject()) {
      // Scalar replaced object in compiled frame
      return new StackValue(((ObjectValue)sv).getValue(), 1);
    }

    // Unknown ScopeValue type
    Assert.that(false, "Should not reach here");
    return new StackValue(0);   // dummy
  }

  private BasicLock resolveMonitorLock(Location location) {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(location.isStack(), "for now we only look at the stack");
    }
    int byteOffset = location.getStackOffset();
    // (stack picture)
    // high: [     ]  byte_offset + wordSize
    // low   [     ]  byte_offset
    //
    // sp->  [     ]  0
    // the byte_offset is the distance from the stack pointer to the lowest address
    // The frame's original stack pointer, before any extension by its callee
    // (due to Compiler1 linkage on SPARC), must be used.
    return new BasicLock(getFrame().getUnextendedSP().addOffsetTo(byteOffset));
  }
}