Statics (Jikes RVM API)

java.lang.Object
- org.jikesrvm.runtime.Statics

public class Statics
extends Object

The static fields and methods comprising a running virtual machine image.

These fields, methods and literal constants form the "root set" of all the objects in the running virtual machine. They are stored in an array where the middle element is always pointed to by the virtual machine's "table of contents" (JTOC) register. The slots of this array hold either primitives (int, long, float, double), object pointers, or array pointers. To enable the garbage collector to differentiate between reference and non-reference values, reference values are indexed positively and numeric values negatively with respect to the middle of the table.

Consider the following declarations:

      class A { static int    i = 123;    }
      class B { static String s = "abc";  }
      class C { static double d = 4.56;   }
      class D { static void m() {} }

Here's a picture of what the corresponding JTOC would look like in memory:

                     +---------------+
                     |     ...       |
                     +---------------+
 field            -6 |   C.d (hi)    |
                     +---------------+
 field            -5 |   C.d (lo)    |
                     +---------------+
 literal          -4 |  4.56 (hi)    |
                     +---------------+
 literal          -3 |  4.56 (lo)    |
                     +---------------+
 field            -2 |     A.i       |
                     +---------------+
 literal          -1 |     123       |
                     +---------------+       +---------------+
 [jtoc register]-> 0:|      0        |       |   (header)    |
                     +---------------+       +---------------+
 literal           1:|  (objref)   --------->|    "abc"      |
                     +---------------+       +---------------+
 field             2:|     B.s       |
                     +---------------+       +---------------+
                   3:|  (coderef)  ------+   |   (header)    |
                     +---------------+   |   +---------------+
                     |     ...       |   +-->|  machine code |
                     +---------------+       |    for "m"    |
                                             +---------------+

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`middleOfTable` The logical middle of the table, references are slots above this and numeric values below this.
`private static int`	`nextNumericSlot` Next available numeric slot number
`private static int`	`nextReferenceSlot` Next available reference slot number
`private static BitVector`	`numericFieldVector` Bit vector indicating whether a numeric slot is a field (true) or a literal (false).
`private static int`	`numericSlotHole` Numeric slot hole.
`private static int`	`numNumericSlots` How many 32bit slots do we want in the JTOC to hold numeric (non-reference) values?
`private static int`	`numReferenceSlots` How many reference-sized slots do we want in the JTOC to hold reference values?
`private static ImmutableEntryIdentityHashMapRVM<Object,Integer>`	`objectLiterals` Map of objects to their literal offsets
`private static Object[]`	`objectSlots` Object version of the slots used during boot image creation and destroyed shortly after.
`private static int[]`	`slots` Static data values (pointed to by JTOC register).

Constructor Summary

Constructors
Constructor and Description

Statics()

Constructors
Constructor and Description
`Statics()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static Offset`	`allocateNumericSlot(int size, boolean field)` Allocate a numeric slot in the JTOC.
`static Offset`	`allocateReferenceSlot(boolean field)` Allocate a reference slot in the JTOC.
`static Object`	`bootImageInstantiationFinished()` Inform Statics that boot image instantiation is over and that unnecessary data structures, for runtime, can be released.
`static void`	`bootImageReportGeneration(Object slots)` After serializing Statics the boot image writer generates a report.
`private static void`	`enlargeTable()` Grow the statics table
`static int`	`findObjectLiteral(Object literal)` Find a slot in the JTOC with this object literal in else return 0
`static int`	`findOrCreate16ByteSizeLiteral(long literal_high, long literal_low)` Find the given literal in the 16byte like literal map, if not found create a slot for the literal and place an entry in the map
`static int`	`findOrCreateIntSizeLiteral(int literal)` Find the given literal in the int like literal map, if not found create a slot for the literal and place an entry in the map
`static int`	`findOrCreateLongSizeLiteral(long literal)` Find the given literal in the long like literal map, if not found create a slot for the literal and place an entry in the map
`static int`	`findOrCreateObjectLiteral(Object literal)` Find or allocate a slot in the JTOC for an object literal.
`static int`	`getHighestInUseSlot()`
`static int`	`getLowestInUseSlot()`
`static int`	`getNumberOfNumericSlots()`
`static int`	`getNumberOfReferenceSlots()`
`static int`	`getReferenceSlotSize()`
`static Address`	`getSlotContentsAsAddress(Offset offset)`
`static int`	`getSlotContentsAsInt(Offset offset)`
`static long`	`getSlotContentsAsLong(Offset offset)`
`static Object`	`getSlotContentsAsObject(Offset offset)`
`static Address`	`getSlots()`
`static int[]`	`getSlotsAsIntArray()`
`static int`	`getTotalNumberOfSlots()`
`static boolean`	`isIntSizeLiteral(int slot)` Does specified JTOC slot contain an int sized literal?
`static boolean`	`isLongSizeLiteral(int slot)` Does specified JTOC slot contain a long sized literal?
`static boolean`	`isReference(int slot)` Does specified JTOC slot contain a reference?
`static boolean`	`isReferenceLiteral(int slot)` Does specified JTOC slot contain a reference literal?
`static void`	`markAsNumericLiteral(int size, Offset fieldOffset)` Marks a slot that was previously a field as being a literal as its value is final.
`static void`	`markAsReferenceLiteral(Offset fieldOffset)` Marks a slot that was previously a field as being a literal as its value is final.
`static int`	`offsetAsSlot(Offset offset)` Conversion from JTOC offset to JTOC slot index.
`static void`	`setSlotContents(Offset offset, Address value)` Set contents of a slot, as a Address
`static void`	`setSlotContents(Offset offset, CodeArray code)` Set contents of a slot, as a CodeArray.
`static void`	`setSlotContents(Offset offset, double value)` Set contents of a slot, as a double.
`static void`	`setSlotContents(Offset offset, Extent value)` Set contents of a slot, as a Extent
`static void`	`setSlotContents(Offset offset, float value)` Set contents of a slot, as an float.
`static void`	`setSlotContents(Offset offset, int value)` Set contents of a slot, as an integer.
`static void`	`setSlotContents(Offset offset, long value)` Set contents of a slot, as a long integer.
`static void`	`setSlotContents(Offset offset, Object object)` Set contents of a slot, as an object.
`static void`	`setSlotContents(Offset offset, Offset value)` Set contents of a slot, as a Offset
`static void`	`setSlotContents(Offset offset, TIB tib)` Set contents of a slot, as a TIB.
`static void`	`setSlotContents(Offset offset, Word word)` Set contents of a slot, as a Word.
`static Offset`	`slotAsOffset(int slot)` Conversion from JTOC slot index to JTOC offset.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - numNumericSlots
```
private static final int numNumericSlots
```
    How many 32bit slots do we want in the JTOC to hold numeric (non-reference) values?
    
    See Also:
    
    Constant Field Values
  - numReferenceSlots
```
private static final int numReferenceSlots
```
    How many reference-sized slots do we want in the JTOC to hold reference values?
    
    See Also:
    
    Constant Field Values
  - slots
```
private static final int[] slots
```
    Static data values (pointed to by JTOC register). This is currently fixed-size, although at one point the system's plans called for making it dynamically growable. We could also make it non-contiguous.
  - objectSlots
```
private static Object[] objectSlots
```
    Object version of the slots used during boot image creation and destroyed shortly after. This is required to support conversion of a slot address to its associated object during boot image creation.
  - middleOfTable
```
public static final int middleOfTable
```
    The logical middle of the table, references are slots above this and numeric values below this. The JTOC points to the middle of the table.
    
    See Also:
    
    Constant Field Values
  - nextNumericSlot
```
private static volatile int nextNumericSlot
```
    Next available numeric slot number
  - numericSlotHole
```
private static volatile int numericSlotHole
```
    Numeric slot hole. Holes are created to align 8byte values. We allocate into a hole rather than consume another numeric slot. The value of middleOfTable indicates the slot isn't in use.
  - nextReferenceSlot
```
private static volatile int nextReferenceSlot
```
    Next available reference slot number
  - numericFieldVector
```
private static final BitVector numericFieldVector
```
    Bit vector indicating whether a numeric slot is a field (true) or a literal (false).
  - objectLiterals
```
private static final ImmutableEntryIdentityHashMapRVM<Object,Integer> objectLiterals
```
    Map of objects to their literal offsets
- Constructor Detail
  - Statics
```
public Statics()
```
- Method Detail
  - slotAsOffset
```
public static Offset slotAsOffset(int slot)
```
    Conversion from JTOC slot index to JTOC offset.
    
    Parameters:
    
    slot - the JTOC slot index
    
    Returns:
    
    the JTOC offset
  - offsetAsSlot
```
public static int offsetAsSlot(Offset offset)
```
    Conversion from JTOC offset to JTOC slot index.
    
    Parameters:
    
    offset - the JTOC offset
    
    Returns:
    
    the JTOC slot index
  - getLowestInUseSlot
```
public static int getLowestInUseSlot()
```
    Returns:
    
    the lowest slot number in use
  - getHighestInUseSlot
```
public static int getHighestInUseSlot()
```
    Returns:
    
    the highest slot number in use
  - findOrCreateIntSizeLiteral
```
public static int findOrCreateIntSizeLiteral(int literal)
```
    Find the given literal in the int like literal map, if not found create a slot for the literal and place an entry in the map
    
    Parameters:
    
    literal - the literal value to find or create
    
    Returns:
    
    the offset in the JTOC of the literal
  - findOrCreateLongSizeLiteral
```
public static int findOrCreateLongSizeLiteral(long literal)
```
    Find the given literal in the long like literal map, if not found create a slot for the literal and place an entry in the map
    
    Parameters:
    
    literal - the literal value to find or create
    
    Returns:
    
    the offset in the JTOC of the literal
  - findOrCreate16ByteSizeLiteral
```
public static int findOrCreate16ByteSizeLiteral(long literal_high,
                                                long literal_low)
```
    Find the given literal in the 16byte like literal map, if not found create a slot for the literal and place an entry in the map
    
    Parameters:
    
    literal_high - the high part of the literal value to find or create
    
    literal_low - the low part of the literal value to find or create
    
    Returns:
    
    the offset in the JTOC of the literal
  - findOrCreateObjectLiteral
```
public static int findOrCreateObjectLiteral(Object literal)
```
    Find or allocate a slot in the JTOC for an object literal.
    
    Parameters:
    
    literal - value
    
    Returns:
    
    offset of slot that was allocated Side effect: literal value is stored into JTOC
  - findObjectLiteral
```
public static int findObjectLiteral(Object literal)
```
    Find a slot in the JTOC with this object literal in else return 0
    
    Parameters:
    
    literal - value
    
    Returns:
    
    offset containing literal or 0
  - markAsNumericLiteral
```
public static void markAsNumericLiteral(int size,
                                        Offset fieldOffset)
```
    Marks a slot that was previously a field as being a literal as its value is final.
    
    Parameters:
    
    size - the slot's size
    
    fieldOffset - the field's offset in the JTOC
  - markAsReferenceLiteral
```
public static void markAsReferenceLiteral(Offset fieldOffset)
```
    Marks a slot that was previously a field as being a literal as its value is final.
    
    Parameters:
    
    fieldOffset - the field's offset in the JTOC
  - allocateNumericSlot
```
public static Offset allocateNumericSlot(int size,
                                         boolean field)
```
    Allocate a numeric slot in the JTOC.
    
    Parameters:
    
    size - of slot
    
    field - is the slot for a field
    
    Returns:
    
    offset of slot that was allocated as int (two slots are allocated for longs and doubles)
  - allocateReferenceSlot
```
public static Offset allocateReferenceSlot(boolean field)
```
    Allocate a reference slot in the JTOC.
    
    Parameters:
    
    field - is the slot for a field
    
    Returns:
    
    offset of slot that was allocated as int (two slots are allocated on 64bit architectures)
  - enlargeTable
```
private static void enlargeTable()
```
    Grow the statics table
  - getNumberOfNumericSlots
```
public static int getNumberOfNumericSlots()
```
    Returns:
    
    number of numeric JTOC slots currently allocated.
  - getNumberOfReferenceSlots
```
public static int getNumberOfReferenceSlots()
```
    Returns:
    
    number of reference JTOC slots currently allocated.
  - getTotalNumberOfSlots
```
public static int getTotalNumberOfSlots()
```
    Returns:
    
    total number of slots comprising the JTOC.
  - isReference
```
public static boolean isReference(int slot)
```
    Does specified JTOC slot contain a reference?
    
    Parameters:
    
    slot - obtained from offsetAsSlot()
    
    Returns:
    
    true --> slot contains a reference
  - isIntSizeLiteral
```
public static boolean isIntSizeLiteral(int slot)
```
    Does specified JTOC slot contain an int sized literal?
    
    Parameters:
    
    slot - obtained from offsetAsSlot()
    
    Returns:
    
    true --> slot contains a reference
  - isLongSizeLiteral
```
public static boolean isLongSizeLiteral(int slot)
```
    Does specified JTOC slot contain a long sized literal?
    
    Parameters:
    
    slot - obtained from offsetAsSlot()
    
    Returns:
    
    true --> slot contains a reference
  - isReferenceLiteral
```
public static boolean isReferenceLiteral(int slot)
```
    Does specified JTOC slot contain a reference literal?
    
    Parameters:
    
    slot - obtained from offsetAsSlot()
    
    Returns:
    
    true --> slot contains a reference
  - getReferenceSlotSize
```
public static int getReferenceSlotSize()
```
    Returns:
    
    size occupied by a reference
  - getSlots
```
public static Address getSlots()
```
    Returns:
    
    JTOC object (for JNI environment and GC).
  - getSlotsAsIntArray
```
public static int[] getSlotsAsIntArray()
```
    Returns:
    
    JTOC object (for JNI environment and GC).
  - getSlotContentsAsInt
```
public static int getSlotContentsAsInt(Offset offset)
```
    Parameters:
    
    offset - the slot's offset in the JTOC
    
    Returns:
    
    contents of a slot, as an integer
  - getSlotContentsAsLong
```
public static long getSlotContentsAsLong(Offset offset)
```
    Parameters:
    
    offset - the slot's offset
    
    Returns:
    
    contents of a slot-pair, as a long integer.
  - getSlotContentsAsObject
```
public static Object getSlotContentsAsObject(Offset offset)
```
    Parameters:
    
    offset - the slot's offset
    
    Returns:
    
    contents of a slot, as an object.
  - getSlotContentsAsAddress
```
public static Address getSlotContentsAsAddress(Offset offset)
```
    Parameters:
    
    offset - the slot's offset
    
    Returns:
    
    contents of a slot, as an Address.
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   int value)
```
    Set contents of a slot, as an integer.
    
    Parameters:
    
    offset - the slot's offset
    
    value - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   float value)
```
    Set contents of a slot, as an float.
    
    Parameters:
    
    offset - the slot's offset
    
    value - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   double value)
```
    Set contents of a slot, as a double.
    
    Parameters:
    
    offset - the slot's offset
    
    value - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   long value)
```
    Set contents of a slot, as a long integer.
    
    Parameters:
    
    offset - the slot's offset
    
    value - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   Object object)
```
    Set contents of a slot, as an object.
    
    Parameters:
    
    offset - the slot's offset
    
    object - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   CodeArray code)
```
    Set contents of a slot, as a CodeArray.
    
    Parameters:
    
    offset - the slot's offset
    
    code - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   TIB tib)
```
    Set contents of a slot, as a TIB.
    
    Parameters:
    
    offset - the slot's offset
    
    tib - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   Word word)
```
    Set contents of a slot, as a Word.
    
    Parameters:
    
    offset - the slot's offset
    
    word - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   Address value)
```
    Set contents of a slot, as a Address
    
    Parameters:
    
    offset - the slot's offset
    
    value - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   Extent value)
```
    Set contents of a slot, as a Extent
    
    Parameters:
    
    offset - the slot's offset
    
    value - new value for the slot
  - setSlotContents
```
public static void setSlotContents(Offset offset,
                                   Offset value)
```
    Set contents of a slot, as a Offset
    
    Parameters:
    
    offset - the slot's offset
    
    value - new value for the slot
  - bootImageInstantiationFinished
```
public static Object bootImageInstantiationFinished()
```
    Inform Statics that boot image instantiation is over and that unnecessary data structures, for runtime, can be released.
    
    Returns:
    
    information that may later be restored to help generate the boot image report
  - bootImageReportGeneration
```
public static void bootImageReportGeneration(Object slots)
```
    After serializing Statics the boot image writer generates a report. This method is called to restore data lost by the call to bootImageInstantiationFinished.
    
    Parameters:
    
    slots - object slots to restore

Class Statics

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

numNumericSlots

numReferenceSlots

slots

objectSlots

middleOfTable

nextNumericSlot

numericSlotHole

nextReferenceSlot

numericFieldVector

objectLiterals

Constructor Detail

Statics

Method Detail

slotAsOffset

offsetAsSlot

getLowestInUseSlot

getHighestInUseSlot

findOrCreateIntSizeLiteral

findOrCreateLongSizeLiteral

findOrCreate16ByteSizeLiteral

findOrCreateObjectLiteral

findObjectLiteral

markAsNumericLiteral

markAsReferenceLiteral

allocateNumericSlot

allocateReferenceSlot

enlargeTable

getNumberOfNumericSlots

getNumberOfReferenceSlots

getTotalNumberOfSlots

isReference

isIntSizeLiteral

isLongSizeLiteral

isReferenceLiteral

getReferenceSlotSize

getSlots

getSlotsAsIntArray

getSlotContentsAsInt

getSlotContentsAsLong

getSlotContentsAsObject

getSlotContentsAsAddress

setSlotContents

setSlotContents

setSlotContents

setSlotContents

setSlotContents

setSlotContents

setSlotContents

setSlotContents

setSlotContents

setSlotContents

setSlotContents

bootImageInstantiationFinished

bootImageReportGeneration