Stamp

java.lang.Object
- org.graalvm.compiler.core.common.type.Stamp

All Implemented Interfaces:

SpeculationReasonGroup.SpeculationContextObject

Direct Known Subclasses:

AbstractPointerStamp, ArithmeticStamp, IllegalStamp, VoidStamp
```
public abstract class Stamp
extends Object
implements SpeculationReasonGroup.SpeculationContextObject
```
A stamp is the basis for a type system.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.graalvm.compiler.serviceprovider.SpeculationReasonGroup.SpeculationContextObject
  SpeculationReasonGroup.SpeculationContextObject.Visitor

Constructor Summary

Constructors
Modifier Constructor and Description

protected Stamp()

Constructors
Modifier	Constructor and Description
`protected`	`Stamp()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`alwaysDistinct(Stamp other)`
`Constant`	`asConstant()` If this stamp represents a single value, the methods returns this single value.
`abstract Stamp`	`constant(Constant c, MetaAccessProvider meta)` If it is possible to represent single value stamps of this kind, this method returns the stamp representing the single value c.
`abstract Stamp`	`empty()` Returns a stamp of the same kind, but with no allowed values.
`abstract LIRKind`	`getLIRKind(LIRKindTool tool)` Gets a platform dependent `LIRKind` that can be used to store a value of this stamp.
`abstract JavaKind`	`getStackKind()` Gets a Java `JavaKind` that can be used to store a value of this stamp on the Java bytecode stack.
`abstract boolean`	`hasValues()` Test whether this stamp has legal values.
`abstract Stamp`	`improveWith(Stamp other)` Tries to improve this stamp with the stamp given as parameter.
`abstract boolean`	`isCompatible(Constant constant)` Check that the constant `other` is compatible with this stamp.
`abstract boolean`	`isCompatible(Stamp other)` Test whether two stamps have the same base type.
`boolean`	`isEmpty()` Tests whether this stamp represents an illegal value.
`boolean`	`isPointerStamp()` Tests whether this stamp represents a pointer value.
`boolean`	`isUnrestricted()` Tests whether this stamp represents all values of this kind.
`abstract ResolvedJavaType`	`javaType(MetaAccessProvider metaAccess)` Returns the type of the stamp, guaranteed to be non-null.
`abstract Stamp`	`join(Stamp other)` Returns the intersection of this stamp and the given stamp.
`SymbolicJVMCIReference<? extends Stamp>`	`makeSymbolic()` Convert a Stamp into a representation that can be resolved symbolically into the original stamp.
`abstract Stamp`	`meet(Stamp other)` Returns the union of this stamp and the given stamp.
`boolean`	`neverDistinct(Stamp other)`
`abstract Constant`	`readConstant(MemoryAccessProvider provider, Constant base, long displacement)` Read a value of this stamp from memory.
`Constant`	`readConstant(MemoryAccessProvider provider, Constant base, long displacement, Stamp accessStamp)` Read a value of this stamp from memory where the underlying storage might be of a different size.
`abstract String`	`toString()`
`Stamp`	`tryImproveWith(Stamp other)` Tries to improve this stamp with the stamp given as parameter.
`abstract Stamp`	`unrestricted()` Returns a stamp of the same kind, but allowing the full value range of the kind.

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

Methods inherited from interface org.graalvm.compiler.serviceprovider.SpeculationReasonGroup.SpeculationContextObject
accept

- Constructor Detail
  - Stamp
```
protected Stamp()
```
- Method Detail
  - javaType
```
public abstract ResolvedJavaType javaType(MetaAccessProvider metaAccess)
```
    Returns the type of the stamp, guaranteed to be non-null. In some cases, this requires the lookup of class meta data, therefore the MetaAccessProvider is mandatory.
  - alwaysDistinct
```
public boolean alwaysDistinct(Stamp other)
```
  - getStackKind
```
public abstract JavaKind getStackKind()
```
    Gets a Java JavaKind that can be used to store a value of this stamp on the Java bytecode stack. Returns JavaKind.Illegal if a value of this stamp can not be stored on the bytecode stack.
  - getLIRKind
```
public abstract LIRKind getLIRKind(LIRKindTool tool)
```
    Gets a platform dependent LIRKind that can be used to store a value of this stamp.
  - meet
```
public abstract Stamp meet(Stamp other)
```
    Returns the union of this stamp and the given stamp. Typically used to create stamps for phi nodes.
    
    Parameters:
    
    other - The stamp that will enlarge this stamp.
    
    Returns:
    
    The union of this stamp and the given stamp.
  - join
```
public abstract Stamp join(Stamp other)
```
    Returns the intersection of this stamp and the given stamp.
    
    Parameters:
    
    other - The stamp that will tighten this stamp.
    
    Returns:
    
    The intersection of this stamp and the given stamp.
  - unrestricted
```
public abstract Stamp unrestricted()
```
    Returns a stamp of the same kind, but allowing the full value range of the kind. Stamp.unrestricted() is the neutral element of the Stamp.join(Stamp) operation.
  - empty
```
public abstract Stamp empty()
```
    Returns a stamp of the same kind, but with no allowed values. Stamp.empty() is the neutral element of the Stamp.meet(Stamp) operation.
  - constant
```
public abstract Stamp constant(Constant c,
                               MetaAccessProvider meta)
```
    If it is possible to represent single value stamps of this kind, this method returns the stamp representing the single value c. stamp.constant(c).asConstant() should be equal to c.
    If it is not possible to represent single value stamps, this method returns a stamp that includes c, and is otherwise as narrow as possible.
  - isCompatible
```
public abstract boolean isCompatible(Stamp other)
```
    Test whether two stamps have the same base type.
  - isCompatible
```
public abstract boolean isCompatible(Constant constant)
```
    Check that the constant other is compatible with this stamp.
    
    Parameters:
    
    constant -
  - hasValues
```
public abstract boolean hasValues()
```
    Test whether this stamp has legal values.
  - isEmpty
```
public final boolean isEmpty()
```
    Tests whether this stamp represents an illegal value.
  - isUnrestricted
```
public boolean isUnrestricted()
```
    Tests whether this stamp represents all values of this kind.
  - isPointerStamp
```
public boolean isPointerStamp()
```
    Tests whether this stamp represents a pointer value.
  - asConstant
```
public Constant asConstant()
```
    If this stamp represents a single value, the methods returns this single value. It returns null otherwise.
    
    Returns:
    
    the constant corresponding to the single value of this stamp and null if this stamp can represent less or more than one value.
  - readConstant
```
public abstract Constant readConstant(MemoryAccessProvider provider,
                                      Constant base,
                                      long displacement)
```
    Read a value of this stamp from memory.
    
    Returns:
    
    the value read or null if the value can't be read for some reason.
  - readConstant
```
public Constant readConstant(MemoryAccessProvider provider,
                             Constant base,
                             long displacement,
                             Stamp accessStamp)
```
    Read a value of this stamp from memory where the underlying storage might be of a different size. accessStamp is used to specify the size of access if it differs from the size of the result.
    
    Returns:
    
    the value read or null if the value can't be read for some reason
    
    Throws:
    
    IllegalArgumentException - if this stamp does not support reading a value of the size specified by accessStamp
  - improveWith
```
public abstract Stamp improveWith(Stamp other)
```
    Tries to improve this stamp with the stamp given as parameter. If successful, returns the new improved stamp. Otherwise, returns a stamp equal to this.
    
    Parameters:
    
    other - the stamp that should be used to improve this stamp
    
    Returns:
    
    the newly improved stamp or a stamp equal to this if an improvement was not possible
  - tryImproveWith
```
public final Stamp tryImproveWith(Stamp other)
```
    Tries to improve this stamp with the stamp given as parameter. If successful, returns the new improved stamp. Otherwise, returns null.
    
    Parameters:
    
    other - the stamp that should be used to improve this stamp
    
    Returns:
    
    the newly improved stamp or null if an improvement was not possible
  - neverDistinct
```
public boolean neverDistinct(Stamp other)
```
  - makeSymbolic
```
public SymbolicJVMCIReference<? extends Stamp> makeSymbolic()
```
    Convert a Stamp into a representation that can be resolved symbolically into the original stamp. If this stamp contains no references to JVMCI types then simply return null.
  - toString
```
public abstract String toString()
```
    Overrides:
    
    toString in class Object

Class Stamp

Nested Class Summary

Nested classes/interfaces inherited from interface org.graalvm.compiler.serviceprovider.SpeculationReasonGroup.SpeculationContextObject

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.graalvm.compiler.serviceprovider.SpeculationReasonGroup.SpeculationContextObject

Constructor Detail

Stamp

Method Detail

javaType

alwaysDistinct

getStackKind

getLIRKind

meet

join

unrestricted

empty

constant

isCompatible

isCompatible

hasValues

isEmpty

isUnrestricted

isPointerStamp

asConstant

readConstant

readConstant

improveWith

tryImproveWith

neverDistinct

makeSymbolic

toString