org.jikesrvm.compilers.opt.runtimesupport

Class OptGenericGCMapIterator

java.lang.Object

org.jikesrvm.mm.mminterface.GCMapIterator

org.jikesrvm.compilers.opt.runtimesupport.OptGenericGCMapIterator

Direct Known Subclasses:

OptGCMapIterator

public abstract class OptGenericGCMapIterator
extends GCMapIterator

This class contains its architecture-independent code for iteration across the references represented by a frame built by the OPT compiler.

The architecture-dependent code is provided by the subclasses of this class.

Field Summary

Fields

Modifier and Type	Field and Description
protected OptCompiledMethod	compiledMethod The compiled method
private int	currentRegister This shows which register to inspect and report on.
private static boolean	DEBUG just used for debugging, all output statements use VM.syswrite
(package private) static boolean	lookForMissedReferencesInRegs when set to true, all registers and spills will be inspected for values that look like references.
(package private) static boolean	lookForMissedReferencesInSpills
private OptMachineCodeMap	map The GC map for this method
private int	mapIndex Used to index into the GC map
private Address	spillLoc This caches the spill location, so that we can check for missed refs hiding in spills
(package private) static boolean	VERBOSE just used for verbose debugging, all output statements use VM.syswrite

Fields inherited from class org.jikesrvm.mm.mminterface.GCMapIterator

framePtr, registerLocations, thread

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	OptGenericGCMapIterator(AddressArray registerLocations)

Method Summary

Modifier and Type	Method and Description
(package private) void	checkAllRegistersForMissedReferences() This method inspects all the registers for values that look like refs.
(package private) void	checkCurrentRegisterForMissedReferences() This method inspects the "current" register for values that look like refs.
(package private) void	checkForMissedSpills(Address ref1, Address ref2) This method inspects spill locations between the parameters passed to determine if they look like heap points If the first parameter is 0, it looks from the beginning of the frame until new.
(package private) void	checkRegistersForMissedReferences(int firstReg, int lastReg) This method inspects the registers from firstReg to lastReg (inclusive) for values that look like pointers.
void	cleanupPointers() scan of this frame is complete clean up any pointers to allow GC to reclaim dead objects
boolean	currentRegisterIsValid() Determines if the value of "currentRegister" is valid, or if we processed all registers
int	getCurrentRegister() return the current register we are processing
abstract Address	getFirstSpillLoc() Get address of the first spill location (The location of spills varies among architectures.)
abstract Address	getLastSpillLoc() Get address of the last spill location (The location of spills varies among architectures.)
Address	getNextReferenceAddress() Returns the next address that contains a reference
Address	getNextReturnAddressAddress() This method is called repeatedly to process derived pointers related to JSRs.
abstract Address	getStackLocation(Address framePtr, int offset) Determine the stack location given the frame ptr and spill offset.
int	getType() Get the type of this iterator (BASELINE, OPT, etc.).
void	reset() Externally visible method called to reset internal state
void	setupIterator(CompiledMethod cm, Offset instructionOffset, Address framePtr) Initialize the iterator for another stack frame scan
void	updateCurrentRegister() update the state of the current register we are processing
protected abstract void	updateLocateRegisters() If any non-volatile gprs were saved by the method being processed then update the registerLocations array with the locations where the registers were saved.

Methods inherited from class org.jikesrvm.mm.mminterface.GCMapIterator

newStackWalk

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

compiledMethod

protected OptCompiledMethod compiledMethod

The compiled method

map

private OptMachineCodeMap map

The GC map for this method

mapIndex

private int mapIndex

Used to index into the GC map

currentRegister

private int currentRegister

This shows which register to inspect and report on. If it is bigger than LAST_GCMAP_REG than we should look at the spills

spillLoc

private Address spillLoc

This caches the spill location, so that we can check for missed refs hiding in spills

DEBUG

private static final boolean DEBUG

just used for debugging, all output statements use VM.syswrite

See Also:

Constant Field Values

VERBOSE

static final boolean VERBOSE

just used for verbose debugging, all output statements use VM.syswrite

See Also:

Constant Field Values

lookForMissedReferencesInRegs

static final boolean lookForMissedReferencesInRegs

when set to true, all registers and spills will be inspected for values that look like references. THIS CAN BE COSTLY. USE WITH CARE

See Also:

Constant Field Values

lookForMissedReferencesInSpills

static final boolean lookForMissedReferencesInSpills

See Also:

Constant Field Values

Constructor Detail

OptGenericGCMapIterator

protected OptGenericGCMapIterator(AddressArray registerLocations)

Method Detail

setupIterator

public final void setupIterator(CompiledMethod cm,
                                Offset instructionOffset,
                                Address framePtr)

Initialize the iterator for another stack frame scan

Specified by:

setupIterator in class GCMapIterator

Parameters:

cm - The compiled method we are interested in

instructionOffset - The place in the method where we currently are

framePtr - The current frame pointer

getNextReferenceAddress

public final Address getNextReferenceAddress()

Returns the next address that contains a reference

Specified by:

getNextReferenceAddress in class GCMapIterator

Returns:

the value of the next reference

getNextReturnAddressAddress

public final Address getNextReturnAddressAddress()

This method is called repeatedly to process derived pointers related to JSRs. (They are pointers to code and need to be updated if the code moves.)

Specified by:

getNextReturnAddressAddress in class GCMapIterator

Returns:

the next code pointer or 0 if no more exist

cleanupPointers

public final void cleanupPointers()

scan of this frame is complete clean up any pointers to allow GC to reclaim dead objects

Specified by:

cleanupPointers in class GCMapIterator

getType

public final int getType()

Description copied from class: GCMapIterator

Get the type of this iterator (BASELINE, OPT, etc.). Called from GCMapIteratorGroup to select which iterator to use for a stackframe. The possible types are specified in CompiledMethod.

Specified by:

getType in class GCMapIterator

Returns:

type code for this iterator

reset

public final void reset()

Externally visible method called to reset internal state

Specified by:

reset in class GCMapIterator

getCurrentRegister

public final int getCurrentRegister()

return the current register we are processing

Returns:

the current register we are processing

updateCurrentRegister

public final void updateCurrentRegister()

update the state of the current register we are processing

currentRegisterIsValid

public final boolean currentRegisterIsValid()

Determines if the value of "currentRegister" is valid, or if we processed all registers

Returns:

whether the currentRegister is valid

updateLocateRegisters

protected abstract void updateLocateRegisters()

If any non-volatile gprs were saved by the method being processed then update the registerLocations array with the locations where the registers were saved.

getStackLocation

public abstract Address getStackLocation(Address framePtr,
                                         int offset)

Determine the stack location given the frame ptr and spill offset. (The offset direction varies among architectures.)

Parameters:

framePtr - the frame pointer

offset - the offset

Returns:

the resulting stack location

getFirstSpillLoc

public abstract Address getFirstSpillLoc()

Get address of the first spill location (The location of spills varies among architectures.)

Returns:

the first spill location

getLastSpillLoc

public abstract Address getLastSpillLoc()

Get address of the last spill location (The location of spills varies among architectures.)

Returns:

the last spill location

checkCurrentRegisterForMissedReferences

final void checkCurrentRegisterForMissedReferences()

This method inspects the "current" register for values that look like refs.

checkAllRegistersForMissedReferences

final void checkAllRegistersForMissedReferences()

This method inspects all the registers for values that look like refs.

checkRegistersForMissedReferences

final void checkRegistersForMissedReferences(int firstReg,
                                             int lastReg)

This method inspects the registers from firstReg to lastReg (inclusive) for values that look like pointers.

Parameters:

firstReg - first reg to check

lastReg - last reg to check

checkForMissedSpills

final void checkForMissedSpills(Address ref1,
                                Address ref2)

This method inspects spill locations between the parameters passed to determine if they look like heap points If the first parameter is 0, it looks from the beginning of the frame until new.

Parameters:

ref1 - the last spill found as a reference

ref2 - the next spill found as a reference