com.ibm.wala.ssa

Class SSAInstruction

java.lang.Object

com.ibm.wala.ssa.SSAInstruction

Direct Known Subclasses:

ReflectiveMemberAccess, SSAAbstractBinaryInstruction, SSAAbstractInvokeInstruction, SSAAbstractThrowInstruction, SSAAbstractUnaryInstruction, SSAAddressOfInstruction, SSAArrayLengthInstruction, SSAArrayReferenceInstruction, SSACheckCastInstruction, SSAComparisonInstruction, SSAConditionalBranchInstruction, SSAConversionInstruction, SSAFieldAccessInstruction, SSAGetCaughtExceptionInstruction, SSAGotoInstruction, SSAInstanceofInstruction, SSALoadMetadataInstruction, SSAMonitorInstruction, SSANewInstruction, SSAPhiInstruction, SSAReturnInstruction, SSAStoreIndirectInstruction, SSASwitchInstruction

public abstract class SSAInstruction
extends java.lang.Object

An instruction in SSA form.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SSAInstruction.IVisitor This interface is used by Instruction.visit to dispatch based on the instruction type.
static class	SSAInstruction.Visitor A base visitor implementation that does nothing.

Field Summary

Fields

Modifier and Type	Field and Description
static int	NO_INDEX

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SSAInstruction(int iindex) prevent instantiation by the outside

Method Summary

Modifier and Type	Method and Description
abstract SSAInstruction	copyForSSA(SSAInstructionFactory insts, int[] defs, int[] uses) This method is meant to be used during SSA conversion for an IR that is not in SSA form.
boolean	equals(java.lang.Object obj) We assume these instructions are canonical and managed by a governing IR object.
int	getDef()
int	getDef(int i) Return the ith def
java.util.Collection<TypeReference>	getExceptionTypes() This method should never return null.
int	getNumberOfDefs()
int	getNumberOfUses()
int	getUse(int j)
protected java.lang.String	getValueString(SymbolTable symbolTable, int valueNumber)
boolean	hasDef() Does this instruction define a normal value, as distinct from a set of exceptions possibly thrown by it (e.g.
abstract int	hashCode()
int	iIndex()
abstract boolean	isFallThrough()
boolean	isPEI()
void	setInstructionIndex(int instructionIndex)
java.lang.String	toString()
abstract java.lang.String	toString(SymbolTable symbolTable)
abstract void	visit(SSAInstruction.IVisitor v) Apply an IVisitor to this instruction.

Methods inherited from class java.lang.Object

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

Field Detail

NO_INDEX

public static final int NO_INDEX

See Also:

Constant Field Values

Constructor Detail

SSAInstruction

protected SSAInstruction(int iindex)

prevent instantiation by the outside

Method Detail

copyForSSA

public abstract SSAInstruction copyForSSA(SSAInstructionFactory insts,
                                          int[] defs,
                                          int[] uses)

This method is meant to be used during SSA conversion for an IR that is not in SSA form. It creates a new SSAInstruction of the same type as the receiver, with a combination of the receiver's uses and defs and those from the method parameters.

In particular, if the 'defs' parameter is null, then the new instruction has the same defs as the receiver. If 'defs' is not null, it must be an array with a size equal to the number of defs that the receiver instruction has. In this case, the new instruction has defs taken from the array. The uses of the new instruction work in the same way with the 'uses' parameter.

Note that this only applies to CAst-based IR translation, since Java bytecode-based IR generation uses a different SSA construction mechanism.

TODO: move this into the SSAInstructionFactory

toString

public abstract java.lang.String toString(SymbolTable symbolTable)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getValueString

protected java.lang.String getValueString(SymbolTable symbolTable,
                                          int valueNumber)

visit

public abstract void visit(SSAInstruction.IVisitor v)

Apply an IVisitor to this instruction. We invoke the appropriate IVisitor method according to the type of this instruction.

hasDef

public boolean hasDef()

Does this instruction define a normal value, as distinct from a set of exceptions possibly thrown by it (e.g. for invoke instructions).

Returns:

true if the instruction does define a proper value.

getDef

public int getDef()

getDef

public int getDef(int i)

Return the ith def

Parameters:

i - number of the def, starting at 0.

getNumberOfDefs

public int getNumberOfDefs()

getNumberOfUses

public int getNumberOfUses()

getUse

public int getUse(int j)
           throws java.lang.UnsupportedOperationException

Returns:

value number representing the jth use in this instruction. -1 means TOP (i.e., the value doesn't matter)

Throws:

java.lang.UnsupportedOperationException

hashCode

public abstract int hashCode()

Overrides:

hashCode in class java.lang.Object

isPEI

public boolean isPEI()

Returns:

true iff this instruction may throw an exception.

getExceptionTypes

public java.util.Collection<TypeReference> getExceptionTypes()

This method should never return null.

Returns:

the set of exception types that an instruction might throw ... disregarding athrows and invokes.

isFallThrough

public abstract boolean isFallThrough()

Returns:

true iff this instruction may fall through to the next

equals

public final boolean equals(java.lang.Object obj)

We assume these instructions are canonical and managed by a governing IR object. Be careful.

Depending on the caching policy (see SSACache), the governing IR may be deleted to reclaim memory and recomputed as needed. When an IR is recomputed, it also creates fresh SSAInstruction objects that will not equal old ones. Thus, do not compare for identity SSAInstructions obtained from distinct calls that retrieve cached values (e.g. distinct CGNode.getIR() calls). See the github issue for details.

Overrides:

equals in class java.lang.Object

iIndex

public int iIndex()

setInstructionIndex

public void setInstructionIndex(int instructionIndex)