org.graalvm.compiler.core.common.cfg

Class Loop<T extends AbstractBlockBase<T>>

java.lang.Object

org.graalvm.compiler.core.common.cfg.Loop<T>

Direct Known Subclasses:

HIRLoop

public abstract class Loop<T extends AbstractBlockBase<T>>
extends Object

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Loop(Loop<T> parent, int index, T header)

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
List<T>	getBlocks()
List<Loop<T>>	getChildren()
int	getDepth()
T	getHeader()
int	getIndex()
List<T>	getLoopExits() Returns the loop exits.
ArrayList<T>	getNaturalExits() Returns the natural exit points: these are the earliest block that are guaranteed to never reach a back-edge.
Loop<T>	getParent()
int	hashCode()
boolean	isAncestorOrSelf(Loop<?> potentialAncestor) Determine if potentialAncestor equals this or an ancestor along the Loop.getParent() link.
boolean	isInverted()
boolean	isLoopExit(T block)
boolean	isNaturalExit(T block)
abstract long	numBackedges()
void	setInverted(boolean inverted)
String	toString()

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Loop

protected Loop(Loop<T> parent,
               int index,
               T header)

Method Detail

numBackedges

public abstract long numBackedges()

toString

public String toString()

Overrides:

toString in class Object

getParent

public Loop<T> getParent()

getChildren

public List<Loop<T>> getChildren()

getDepth

public int getDepth()

getIndex

public int getIndex()

getHeader

public T getHeader()

getBlocks

public List<T> getBlocks()

isInverted

public boolean isInverted()

setInverted

public void setInverted(boolean inverted)

isAncestorOrSelf

public boolean isAncestorOrSelf(Loop<?> potentialAncestor)

Determine if potentialAncestor equals this or an ancestor along the Loop.getParent() link.

getLoopExits

public List<T> getLoopExits()

Returns the loop exits. This might be a conservative set: before framestate assignment it matches the LoopExitNodes even if earlier blocks could be considered as exits. After framestate assignments, this is the same as Loop.getNaturalExits().

LoopExitNodes are inserted in the control-flow during parsing and are natural exits: they are the earliest block at which we are guaranteed to have exited the loop. However, after some transformations of the graph, the natural exit might go up but the LoopExitNodes are not updated.

For example in:

 for (int i = 0; i < N; i++) {
     if (c) {
         // Block 1
         if (dummy) {
             // ...
         } else {
             // ...
         }
         if (b) {
             continue;
         } else {
             // Block 2
             // LoopExitNode
             break;
         }
     }
 }
 

After parsing, the natural exits match the LoopExitNode: Block 2 is a natural exit and has a LoopExitNode. If the b condition gets canonicalized to false, the natural exit moves to Block 1 while the LoopExitNode remains in Block 2. In such a scenario, getLoopExits() will contain block 2 while Loop.getNaturalExits() will contain block 1.

See Also:

Loop.getNaturalExits()

isLoopExit

public boolean isLoopExit(T block)

getNaturalExits

public ArrayList<T> getNaturalExits()

Returns the natural exit points: these are the earliest block that are guaranteed to never reach a back-edge. This can not be used in the context of preserving or using loop-closed form.

See Also:

Loop.getLoopExits()

isNaturalExit

public boolean isNaturalExit(T block)

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object