PhiExpr (Soot API)

All Superinterfaces:

EquivTo, Expr, java.io.Serializable, ShimpleExpr, Switchable, UnitBoxOwner, Value

All Known Implementing Classes:

SPhiExpr
```
public interface PhiExpr
extends ShimpleExpr
```
A fully defined PhiExpr usually consists of a list of Values for the arguments alongst with the corresponding control flow predecessor for each argument. This may be provided either as a Soot CFG Block or more directly as the Unit at the end of the corresponding CFG block.
As much as possible we try to conform to the semantics as described by Cytron et al., TOPLAS Oct. 91. A Phi node such as "x_1 = Phi(x_2, x_3)" is eliminated by respectively adding the statements "x_1 = x_2" and "x_1 = x_3" at the end of the corresponding control flow predecessor.
However, due to the fact that each argument is explicitly associated with the control flow predecessor, there may be some subtle differences. We tried to make the behaviour as robust and transparent as possible by handling the common cases of Unit chain manipulations in the Shimple internal implementation of PatchingChain.

Author:

Navindra Umanee

See Also:
Efficiently Computing Static Single Assignment Form and the Control Dependence Graph, Shimple.newPhiExpr(List, List), Shimple.newPhiExpr(Local, List)

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`addArg(Value arg, Block pred)` Add the given argument associated with the given CFG predecessor.
`boolean`	`addArg(Value arg, Unit predTailUnit)` Add the given argument associated with the given CFG predecessor.
`void`	`apply(Switch sw)` Called when this object is visited.
`ValueUnitPair`	`getArgBox(Block pred)` Returns the argument pair corresponding to the given CFG predecessor.
`ValueUnitPair`	`getArgBox(int index)` Returns the argument pair for the given index.
`ValueUnitPair`	`getArgBox(Unit predTailUnit)` Returns the argument pair corresponding to the given CFG predecessor.
`int`	`getArgCount()` Returns the number of arguments in this PhiExpr.
`int`	`getArgIndex(Block pred)` Returns the index of the argument associated with the given control flow predecessor.
`int`	`getArgIndex(Unit predTailUnit)` Returns the index of the argument associated with the given control flow predecessor Unit.
`java.util.List<ValueUnitPair>`	`getArgs()` Returns an unmodifiable, backed view of the arguments to this PhiExpr.
`int`	`getBlockId()` Returns the id number of the block from which the Phi node originated from.
`Unit`	`getPred(int index)` Returns the control flow predecessor Unit for the given index into the PhiExpr.
`java.util.List<Unit>`	`getPreds()` Returns a list of the control flow predecessor Units being tracked by this PhiExpr
`Type`	`getType()` The type of the PhiExpr is usually the same as the type of its arguments.
`Value`	`getValue(Block pred)` Get the PhiExpr argument corresponding to the given control flow predecessor, returns null if not available.
`Value`	`getValue(int index)` Returns the value for the given index into the PhiExpr.
`Value`	`getValue(Unit predTailUnit)` Get the PhiExpr argument corresponding to the given control flow predecessor, returns null if not available.
`java.util.List<Value>`	`getValues()` Returns a list of the values used by this PhiExpr.
`boolean`	`removeArg(Block pred)` Remove the argument corresponding to the given CFG predecessor.
`boolean`	`removeArg(int index)` Remove the argument at the given index.
`boolean`	`removeArg(Unit predTailUnit)` Remove the argument corresponding to the given CFG predecessor.
`boolean`	`removeArg(ValueUnitPair arg)` Remove the given argument.
`boolean`	`setArg(int index, Value arg, Block pred)` Modify the PhiExpr argument at the given index with the given information.
`boolean`	`setArg(int index, Value arg, Unit predTailUnit)` Modify the PhiExpr argument at the given index with the given information.
`void`	`setBlockId(int blockId)` Set the block number of the Phi node.
`boolean`	`setPred(int index, Block pred)` Update the CFG predecessor associated with the PhiExpr argument at the given index.
`boolean`	`setPred(int index, Unit predTailUnit)` Update the CFG predecessor associated with the PhiExpr argument at the given index.
`boolean`	`setValue(Block pred, Value arg)` Locate the argument associated with the given CFG predecessor and set the value.
`boolean`	`setValue(int index, Value arg)` Set the value at the given index into the PhiExpr.
`boolean`	`setValue(Unit predTailUnit, Value arg)` Locate the argument associated with the given CFG predecessor unit and set the value.

Methods inherited from interface soot.Value
clone, getUseBoxes, toString

Methods inherited from interface soot.EquivTo
equivHashCode, equivTo

Methods inherited from interface soot.UnitBoxOwner
clearUnitBoxes, getUnitBoxes

- Method Detail
  - getArgs
```
java.util.List<ValueUnitPair> getArgs()
```
    Returns an unmodifiable, backed view of the arguments to this PhiExpr. Each argument is a ValueUnitPair.
    
    See Also:
    ValueUnitPair
  - getValues
```
java.util.List<Value> getValues()
```
    Returns a list of the values used by this PhiExpr.
  - getPreds
```
java.util.List<Unit> getPreds()
```
    Returns a list of the control flow predecessor Units being tracked by this PhiExpr
  - getArgCount
```
int getArgCount()
```
    Returns the number of arguments in this PhiExpr.
  - getArgBox
```
ValueUnitPair getArgBox(int index)
```
    Returns the argument pair for the given index. Null if out-of-bounds.
  - getValue
```
Value getValue(int index)
```
    Returns the value for the given index into the PhiExpr. Null if out-of-bounds.
  - getPred
```
Unit getPred(int index)
```
    Returns the control flow predecessor Unit for the given index into the PhiExpr. Null if out-of-bounds.
  - getArgIndex
```
int getArgIndex(Unit predTailUnit)
```
    Returns the index of the argument associated with the given control flow predecessor Unit. Returns -1 if not found.
  - getArgBox
```
ValueUnitPair getArgBox(Unit predTailUnit)
```
    Returns the argument pair corresponding to the given CFG predecessor. Returns null if not found.
  - getValue
```
Value getValue(Unit predTailUnit)
```
    Get the PhiExpr argument corresponding to the given control flow predecessor, returns null if not available.
  - getArgIndex
```
int getArgIndex(Block pred)
```
    Returns the index of the argument associated with the given control flow predecessor. Returns -1 if not found.
  - getArgBox
```
ValueUnitPair getArgBox(Block pred)
```
    Returns the argument pair corresponding to the given CFG predecessor. Returns null if not found.
  - getValue
```
Value getValue(Block pred)
```
    Get the PhiExpr argument corresponding to the given control flow predecessor, returns null if not available.
  - setArg
```
boolean setArg(int index,
             Value arg,
             Unit predTailUnit)
```
    Modify the PhiExpr argument at the given index with the given information. Returns false on failure.
  - setArg
```
boolean setArg(int index,
             Value arg,
             Block pred)
```
    Modify the PhiExpr argument at the given index with the given information. Returns false on failure.
  - setValue
```
boolean setValue(int index,
               Value arg)
```
    Set the value at the given index into the PhiExpr. Returns false on failure.
  - setValue
```
boolean setValue(Unit predTailUnit,
               Value arg)
```
    Locate the argument associated with the given CFG predecessor unit and set the value. Returns false on failure.
  - setValue
```
boolean setValue(Block pred,
               Value arg)
```
    Locate the argument associated with the given CFG predecessor and set the value. Returns false on failure.
  - setPred
```
boolean setPred(int index,
              Unit predTailUnit)
```
    Update the CFG predecessor associated with the PhiExpr argument at the given index. Returns false on failure.
  - setPred
```
boolean setPred(int index,
              Block pred)
```
    Update the CFG predecessor associated with the PhiExpr argument at the given index. Returns false on failure.
  - removeArg
```
boolean removeArg(int index)
```
    Remove the argument at the given index. Returns false on failure.
  - removeArg
```
boolean removeArg(Unit predTailUnit)
```
    Remove the argument corresponding to the given CFG predecessor. Returns false on failure.
  - removeArg
```
boolean removeArg(Block pred)
```
    Remove the argument corresponding to the given CFG predecessor. Returns false on failure.
  - removeArg
```
boolean removeArg(ValueUnitPair arg)
```
    Remove the given argument. Returns false on failure.
  - addArg
```
boolean addArg(Value arg,
             Block pred)
```
    Add the given argument associated with the given CFG predecessor. Returns false on failure.
  - addArg
```
boolean addArg(Value arg,
             Unit predTailUnit)
```
    Add the given argument associated with the given CFG predecessor. Returns false on failure.
  - setBlockId
```
void setBlockId(int blockId)
```
    Set the block number of the Phi node.
  - getBlockId
```
int getBlockId()
```
    Returns the id number of the block from which the Phi node originated from.
  - getType
```
Type getType()
```
    The type of the PhiExpr is usually the same as the type of its arguments.
    
    Specified by:
    
    getType in interface Value
  - apply
```
void apply(Switch sw)
```
    Description copied from interface: Switchable
    
    Called when this object is visited.
    
    Specified by:
    
    apply in interface Switchable

Interface PhiExpr

Method Summary

Methods inherited from interface soot.Value

Methods inherited from interface soot.EquivTo

Methods inherited from interface soot.UnitBoxOwner

Method Detail

getArgs

getValues

getPreds

getArgCount

getArgBox

getValue

getPred

getArgIndex

getArgBox

getValue

getArgIndex

getArgBox

getValue

setArg

setArg

setValue

setValue

setValue

setPred

setPred

removeArg

removeArg

removeArg

removeArg

addArg

addArg

setBlockId

getBlockId

getType

apply