LIRKind (Graal OpenJDK Project Documentation)

java.lang.Object
- jdk.internal.jvmci.meta.LIRKind

```
public final class LIRKind
extends Object
```
Represents the type of values in the LIR. It is composed of a PlatformKind that gives the low level representation of the value, and a referenceMask that describes the location of object references in the value, and optionally a derivedReferenceBase.
Constructing LIRKind instances
During LIR generation, every new Value should get a LIRKind of the correct PlatformKind that also contains the correct reference information. LIRKinds should be created as follows:
If the result value is created from one or more input values, the LIRKind should be created with combine(jdk.internal.jvmci.meta.Value...)(inputs). If the result has a different PlatformKind than the inputs, combine(jdk.internal.jvmci.meta.Value...)(inputs).changeType(jdk.internal.jvmci.meta.PlatformKind)(resultKind) should be used.
If the result is an exact copy of one of the inputs, Value.getLIRKind() can be used. Note that this is only correct for move-like operations, like conditional move or compare-and-swap. For convert operations, combine(jdk.internal.jvmci.meta.Value...) should be used.
If it is known that the result will be a reference (e.g. pointer arithmetic where the end result is a valid oop), reference(jdk.internal.jvmci.meta.PlatformKind) should be used.
If it is known that the result will neither be a reference nor be derived from a reference, value(jdk.internal.jvmci.meta.PlatformKind) can be used. If the operation producing this value has inputs, this is very likely wrong, and combine(jdk.internal.jvmci.meta.Value...) should be used instead.
If it is known that the result is derived from a reference in a way that the garbage collector can not track, unknownReference(jdk.internal.jvmci.meta.PlatformKind) can be used. In most cases, combine(jdk.internal.jvmci.meta.Value...) should be used instead, since it is able to detect this automatically.

Field Summary

Fields
Modifier and Type	Field and Description
`private AllocatableValue`	`derivedReferenceBase`
`static LIRKind`	`Illegal` The non-type.
`private PlatformKind`	`platformKind`
`private int`	`referenceMask`
`private static int`	`UNKNOWN_REFERENCE`

Constructor Summary

Constructors
Modifier Constructor and Description

private LIRKind(PlatformKind platformKind, int referenceMask, AllocatableValue derivedReferenceBase)

Constructors
Modifier	Constructor and Description
`private`	`LIRKind(PlatformKind platformKind, int referenceMask, AllocatableValue derivedReferenceBase)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`LIRKind`	`changeType(PlatformKind newPlatformKind)` Create a new `LIRKind` with the same reference information and a new platform kind.
`static LIRKind`	`combine(Value... inputs)` Derive a new type from inputs.
`static LIRKind`	`combineDerived(LIRKind kind, AllocatableValue base1, AllocatableValue base2)` Helper method to construct derived reference kinds.
`static AllocatableValue`	`derivedBaseFromValue(AllocatableValue value)` Helper method to construct derived reference kinds.
`static LIRKind`	`derivedReference(PlatformKind platformKind, AllocatableValue base)` Create a `LIRKind` of type `platformKind` that contains a derived reference.
`boolean`	`equals(Object obj)`
`AllocatableValue`	`getDerivedReferenceBase()` Get the base value of a derived reference.
`PlatformKind`	`getPlatformKind()` Get the low level type that is used in code generation.
`int`	`getReferenceCount()`
`int`	`hashCode()`
`boolean`	`isDerivedReference()` Check whether this value is a derived reference.
`boolean`	`isReference(int idx)` Check whether the `idx`th part of this value is a reference that must be tracked at safepoints.
`boolean`	`isUnknownReference()` Check whether this value is derived from a reference in a non-linear way.
`boolean`	`isValue()` Check whether this kind is a value type that doesn't need to be tracked at safepoints.
`LIRKind`	`makeDerivedReference(AllocatableValue base)` Create a derived reference.
`LIRKind`	`makeUnknownReference()` Create a new `LIRKind` with the same type, but marked as containing an `unknownReference(jdk.internal.jvmci.meta.PlatformKind)`.
`static LIRKind`	`merge(Iterable<LIRKind> kinds)`
`static LIRKind`	`merge(Value... inputs)` Merge the types of the inputs.
`static LIRKind`	`reference(PlatformKind platformKind)` Create a `LIRKind` of type `platformKind` that contains a single tracked oop reference.
`LIRKind`	`repeat(PlatformKind newPlatformKind)` Create a new `LIRKind` with a new platform kind.
`void`	`setDerivedReferenceBase(AllocatableValue derivedReferenceBase)` Change the base value of a derived reference.
`private static PlatformKind`	`toStackKind(PlatformKind platformKind)`
`String`	`toString()`
`static LIRKind`	`unknownReference(PlatformKind platformKind)` Create a `LIRKind` of type `platformKind` that contains a value that is derived from a reference in a non-linear way.
`static LIRKind`	`value(PlatformKind platformKind)` Create a `LIRKind` of type `platformKind` that contains a primitive value.
`private static boolean`	`verifyMerge(LIRKind mergeKind, Iterable<LIRKind> kinds)`
`static boolean`	`verifyMoveKinds(LIRKind dst, LIRKind src)`

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

- Field Detail
  - Illegal
```
public static final LIRKind Illegal
```
    The non-type. This uses unknownReference(jdk.internal.jvmci.meta.PlatformKind), so it can never be part of an oop map.
  - platformKind
```
private final PlatformKind platformKind
```
  - referenceMask
```
private final int referenceMask
```
  - derivedReferenceBase
```
private AllocatableValue derivedReferenceBase
```
  - UNKNOWN_REFERENCE
```
private static final int UNKNOWN_REFERENCE
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - LIRKind
```
private LIRKind(PlatformKind platformKind,
                int referenceMask,
                AllocatableValue derivedReferenceBase)
```
- Method Detail
  - value
```
public static LIRKind value(PlatformKind platformKind)
```
    Create a LIRKind of type platformKind that contains a primitive value. Should be only used when it's guaranteed that the value is not even indirectly derived from a reference. Otherwise, combine(Value...) should be used instead.
  - reference
```
public static LIRKind reference(PlatformKind platformKind)
```
    Create a LIRKind of type platformKind that contains a single tracked oop reference.
  - derivedReference
```
public static LIRKind derivedReference(PlatformKind platformKind,
                                       AllocatableValue base)
```
    Create a LIRKind of type platformKind that contains a derived reference.
  - unknownReference
```
public static LIRKind unknownReference(PlatformKind platformKind)
```
    Create a LIRKind of type platformKind that contains a value that is derived from a reference in a non-linear way. Values of this LIRKind can not be live at safepoints. In most cases, this should not be called directly. combine(jdk.internal.jvmci.meta.Value...) should be used instead to automatically propagate this information.
  - makeDerivedReference
```
public LIRKind makeDerivedReference(AllocatableValue base)
```
    Create a derived reference.
    
    Parameters:
    
    base - An AllocatableValue containing the base pointer of the derived reference.
  - combine
```
public static LIRKind combine(Value... inputs)
```
    Derive a new type from inputs. The result will have the PlatformKind of one of the inputs. If all inputs are values, the result is a value. Otherwise, the result is an unknown reference. This method should be used to construct the result LIRKind of any operation that modifies values (e.g. arithmetics).
  - merge
```
public static LIRKind merge(Value... inputs)
```
    Merge the types of the inputs. The result will have the PlatformKind of one of the inputs. If all inputs are values (references), the result is a value (reference). Otherwise, the result is an unknown reference. This method should be used to construct the result LIRKind of merge operation that does not modify values (e.g. phis).
  - derivedBaseFromValue
```
public static AllocatableValue derivedBaseFromValue(AllocatableValue value)
```
    Helper method to construct derived reference kinds. Returns the base value of a reference or derived reference. For values it returns null, and for unknown references it returns Value.ILLEGAL.
  - combineDerived
```
public static LIRKind combineDerived(LIRKind kind,
                                     AllocatableValue base1,
                                     AllocatableValue base2)
```
    Helper method to construct derived reference kinds. If one of base1 or base2 are set, it creates a derived reference using it as the base. If both are set, the result is an unknown reference.
  - merge
```
public static LIRKind merge(Iterable<LIRKind> kinds)
```
    See Also:
    
    merge(Value...)
  - verifyMerge
```
private static boolean verifyMerge(LIRKind mergeKind,
                                   Iterable<LIRKind> kinds)
```
  - changeType
```
public LIRKind changeType(PlatformKind newPlatformKind)
```
    Create a new LIRKind with the same reference information and a new platform kind. If the new kind is a longer vector than this, the new elements are marked as untracked values.
  - repeat
```
public LIRKind repeat(PlatformKind newPlatformKind)
```
    Create a new LIRKind with a new platform kind. If the new kind is longer than this, the reference positions are repeated to fill the vector.
  - makeUnknownReference
```
public LIRKind makeUnknownReference()
```
    Create a new LIRKind with the same type, but marked as containing an unknownReference(jdk.internal.jvmci.meta.PlatformKind).
  - getPlatformKind
```
public PlatformKind getPlatformKind()
```
    Get the low level type that is used in code generation.
  - isDerivedReference
```
public boolean isDerivedReference()
```
    Check whether this value is a derived reference.
  - getDerivedReferenceBase
```
public AllocatableValue getDerivedReferenceBase()
```
    Get the base value of a derived reference.
  - setDerivedReferenceBase
```
public void setDerivedReferenceBase(AllocatableValue derivedReferenceBase)
```
    Change the base value of a derived reference. This must be called on derived references only.
  - isUnknownReference
```
public boolean isUnknownReference()
```
    Check whether this value is derived from a reference in a non-linear way. If this returns true, this value must not be live at safepoints.
  - getReferenceCount
```
public int getReferenceCount()
```
  - isReference
```
public boolean isReference(int idx)
```
    Check whether the idxth part of this value is a reference that must be tracked at safepoints.
    
    Parameters:
    
    idx - The index into the vector if this is a vector kind. Must be 0 if this is a scalar kind.
  - isValue
```
public boolean isValue()
```
    Check whether this kind is a value type that doesn't need to be tracked at safepoints.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    
    equals in class Object
  - verifyMoveKinds
```
public static boolean verifyMoveKinds(LIRKind dst,
                                      LIRKind src)
```
  - toStackKind
```
private static PlatformKind toStackKind(PlatformKind platformKind)
```

Class LIRKind

Constructing LIRKind instances

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

Illegal

platformKind

referenceMask

derivedReferenceBase

UNKNOWN_REFERENCE

Constructor Detail

LIRKind

Method Detail

value

reference

derivedReference

unknownReference

makeDerivedReference

combine

merge

derivedBaseFromValue

combineDerived

merge

verifyMerge

changeType

repeat

makeUnknownReference

getPlatformKind

isDerivedReference

getDerivedReferenceBase

setDerivedReferenceBase

isUnknownReference

getReferenceCount

isReference

isValue

toString

hashCode

equals

verifyMoveKinds

toStackKind

Constructing `LIRKind` instances