Class IR

java.lang.Object

com.ibm.wala.ssa.IR

All Implemented Interfaces:

IRView

Direct Known Subclasses:

AstIRFactory.AstIR, SyntheticIR

public abstract class IR
extends Object
implements IRView

An SSA IR.

The IR (Intermediate Representation) is the central data structure that represents the instructions of a particular method. The IR represents a method's instructions in a language close to JVM bytecode, but in an SSA-based register transfer language which eliminates the stack abstraction, relying instead on a set of symbolic registers. The IR organizes instructions in a control-flow graph of basic blocks, as typical in compiler textbooks.

See more details on the IR API.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	IR.SSA2LocalMap	A Map that gives the names of the local variables corresponding to SSA value numbers at particular IR instruction indices, if such information is available from source code mapping.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	IR(IMethod method, SSAInstruction[] instructions, SymbolTable symbolTable, SSACFG cfg, SSAOptions options)	Simple constructor when someone else has already computed the symbol table and cfg.

Method Summary

Modifier and Type	Method	Description
ISSABasicBlock	getBasicBlockForCatch(SSAGetCaughtExceptionInstruction instruction)	Return the ISSABasicBlock corresponding to a particular catch instruction
ISSABasicBlock	getBasicBlockForInstruction(SSAInstruction s)	This is space-inefficient.
ISSABasicBlock[]	getBasicBlocksForCall(CallSiteReference site)
Iterator<ISSABasicBlock>	getBlocks()
IntSet	getCallInstructionIndices(CallSiteReference site)	Return the instruction indices corresponding to a call site.
SSAAbstractInvokeInstruction[]	getCalls(CallSiteReference site)	Return the invoke instructions corresponding to a call site
SSACFG	getControlFlowGraph()
SSACFG.BasicBlock	getExitBlock()
protected abstract <T extends SSAIndirectionData.Name> SSAIndirectionData<T>	getIndirectionData()	subclasses must provide information about indirect use of values, if appropriate, and otherwise null
SSAInstruction[]	getInstructions()	Returns the normal instructions.
protected abstract IR.SSA2LocalMap	getLocalMap()	subclasses must provide a source name mapping, if they want one (or null otherwise)
String[]	getLocalNames(int index, int vn)
IMethod	getMethod()
SSANewInstruction	getNew(NewSiteReference site)	Return the new instruction corresponding to an allocation site
int	getNewInstructionIndex(NewSiteReference site)	Return the instruction index corresponding to an allocation site
int	getNumberOfParameters()
SSAOptions	getOptions()
int	getParameter(int i)
TypeReference	getParameterType(int i)	Get the TypeReference that describes the ith parameter to this method.
int[]	getParameterValueNumbers()
SSAInstruction	getPEI(ProgramCounter pc)
SymbolTable	getSymbolTable()
protected abstract String	instructionPosition(int instructionIndex)
boolean	isEmptyIR()	TODO: why do we need this? We should enforce instructions == null if necessary, I think.
Iterator<SSAInstruction>	iterateAllInstructions()
Iterator<CallSiteReference>	iterateCallSites()
Iterator<SSAInstruction>	iterateCatchInstructions()
Iterator<NewSiteReference>	iterateNewSites()
Iterator<SSAInstruction>	iterateNormalInstructions()
Iterator<? extends SSAInstruction>	iteratePhis()	Return an Iterator of all SSAPhiInstructions for this IR.
Iterator<? extends SSAInstruction>	iteratePis()	Return an Iterator of all SSAPiInstructions for this IR.
protected void	setupLocationMap()	create mappings from call sites, new sites, and PEIs to instruction index
String	toString()
void	visitAllInstructions(SSAInstruction.IVisitor v)	visit each instruction in this IR
void	visitNormalInstructions(SSAInstruction.IVisitor v)	visit each normal (non-phi, non-pi, non-catch) instruction in this IR

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

IR

protected IR(IMethod method,
 SSAInstruction[] instructions,
 SymbolTable symbolTable,
 SSACFG cfg,
 SSAOptions options)

Simple constructor when someone else has already computed the symbol table and cfg.

Method Details

getLocalMap

protected abstract IR.SSA2LocalMap getLocalMap()

subclasses must provide a source name mapping, if they want one (or null otherwise)

getIndirectionData

protected abstract <T extends SSAIndirectionData.Name>
SSAIndirectionData<T> getIndirectionData()

subclasses must provide information about indirect use of values, if appropriate, and otherwise null

setupLocationMap

protected void setupLocationMap()

create mappings from call sites, new sites, and PEIs to instruction index

instructionPosition

protected abstract String instructionPosition(int instructionIndex)

Returns:

a String which is a readable representation of the instruction position corresponding to an instruction index

toString

public String toString()

Overrides:

toString in class Object

getInstructions

public SSAInstruction[] getInstructions()

Returns the normal instructions. Does not include SSAPhiInstruction, SSAPiInstruction, or SSAGetCaughtExceptionInstructions, which are currently managed by SSACFG.BasicBlock. Entries in the returned array might be null.

This may go away someday.

Specified by:

getInstructions in interface IRView

getSymbolTable

public SymbolTable getSymbolTable()

Specified by:

getSymbolTable in interface IRView

Returns:

the SymbolTable managing attributes for values in this method

getControlFlowGraph

public SSACFG getControlFlowGraph()

Specified by:

getControlFlowGraph in interface IRView

Returns:

the underlying ControlFlowGraph which defines this IR.

getBlocks

public Iterator<ISSABasicBlock> getBlocks()

Specified by:

getBlocks in interface IRView

iteratePhis

public Iterator<? extends SSAInstruction> iteratePhis()

Return an Iterator of all SSAPhiInstructions for this IR.

iteratePis

public Iterator<? extends SSAInstruction> iteratePis()

Return an Iterator of all SSAPiInstructions for this IR.

getParameterValueNumbers

public int[] getParameterValueNumbers()

Returns:

array of value numbers representing parameters to this method

getParameter

public int getParameter(int i)

Returns:

the value number of the ith parameter

getParameterType

public TypeReference getParameterType(int i)

Get the TypeReference that describes the ith parameter to this method. By convention, for a non-static method, the 0th parameter is "this".

getNumberOfParameters

public int getNumberOfParameters()

Returns:

number of parameters to this method, including "this"

getMethod

public IMethod getMethod()

Specified by:

getMethod in interface IRView

Returns:

the method this IR represents

iterateCatchInstructions

public Iterator<SSAInstruction> iterateCatchInstructions()

Returns:

iterator of the catch instructions in this IR

visitNormalInstructions

public void visitNormalInstructions(SSAInstruction.IVisitor v)

visit each normal (non-phi, non-pi, non-catch) instruction in this IR

visitAllInstructions

public void visitAllInstructions(SSAInstruction.IVisitor v)

visit each instruction in this IR

iterateNormalInstructions

public Iterator<SSAInstruction> iterateNormalInstructions()

Returns:

an Iterator of all "normal" instructions on this IR

iterateAllInstructions

public Iterator<SSAInstruction> iterateAllInstructions()

Returns:

an Iterator of all instructions (Normal, Phi, and Catch)

getExitBlock

public SSACFG.BasicBlock getExitBlock()

Specified by:

getExitBlock in interface IRView

Returns:

the exit basic block

getCalls

public SSAAbstractInvokeInstruction[] getCalls(CallSiteReference site)

Return the invoke instructions corresponding to a call site

Note that Shrike may inline JSRS. This can lead to multiple copies of a single bytecode instruction in a particular IR. So we may have more than one instruction index for a particular call site from bytecode.

getCallInstructionIndices

public IntSet getCallInstructionIndices(CallSiteReference site)

Return the instruction indices corresponding to a call site.

Note that Shrike may inline JSRS. This can lead to multiple copies of a single bytecode instruction in a particular IR. So we may have more than one instruction index for a particular call site from bytecode.

getNew

public SSANewInstruction getNew(NewSiteReference site)

Return the new instruction corresponding to an allocation site

getNewInstructionIndex

public int getNewInstructionIndex(NewSiteReference site)

Return the instruction index corresponding to an allocation site

getPEI

public SSAInstruction getPEI(ProgramCounter pc)

Specified by:

getPEI in interface IRView

Parameters:

pc - a program counter

Returns:

the instruction (a PEI) at this program counter

iterateNewSites

public Iterator<NewSiteReference> iterateNewSites()

Specified by:

iterateNewSites in interface IRView

Returns:

an Iterator of all the allocation sites ( NewSiteReferences ) in this IR

iterateCallSites

public Iterator<CallSiteReference> iterateCallSites()

Specified by:

iterateCallSites in interface IRView

Returns:

an Iterator of all the call sites ( CallSiteReferences ) in this IR

getBasicBlocksForCall

public ISSABasicBlock[] getBasicBlocksForCall(CallSiteReference site)

Specified by:

getBasicBlocksForCall in interface IRView

Parameters:

site - a call site in this method

Returns:

the basic block corresponding to this instruction

Throws:

IllegalArgumentException - if site is null

getBasicBlockForInstruction

public ISSABasicBlock getBasicBlockForInstruction(SSAInstruction s)

This is space-inefficient. Use with care.

Be very careful; note the strange identity semantics of SSAInstruction, using ==. You can't mix SSAInstructions and IRs freely.

isEmptyIR

public boolean isEmptyIR()

TODO: why do we need this? We should enforce instructions == null if necessary, I think.

Returns:

true iff every instruction is null

getLocalNames

public String[] getLocalNames(int index,
 int vn)

Specified by:

getLocalNames in interface IRView

Parameters:

index - an index into the IR instruction array

vn - a value number

Returns:

if we know that immediately after the given program counter, v_vn corresponds to one or more locals and local variable names are available, the name of the locals which v_vn represents. Otherwise, null.

getBasicBlockForCatch

public ISSABasicBlock getBasicBlockForCatch(SSAGetCaughtExceptionInstruction instruction)

Return the ISSABasicBlock corresponding to a particular catch instruction

getOptions

public SSAOptions getOptions()

Returns:

the SSAOptions which controlled how this IR was built