org.jikesrvm.compilers.opt.ssa
Class PiNodes

java.lang.Object
  org.jikesrvm.compilers.opt.driver.CompilerPhase
      org.jikesrvm.compilers.opt.ssa.PiNodes

public final class PiNodes
extends CompilerPhase

This pass inserts PI nodes (Effectively copies) on branch edges, to introduce new names for analysis

CHECK_REF_PI

static final boolean CHECK_REF_PI

Should we insert PI nodes for array references after bounds-checks and null-checks? TODO: if this is false, then null-check elimination will be ineffective. TODO: prove that null-check elimination is sound before turning this on again.

See Also:

Constant Field Values

insertion

final boolean insertion

Should we insert (true) or delete (false) PI nodes?

typeChecks

final boolean typeChecks

Are we adding pi nodes for type checks only? This is for GNOSYS analysis right now.

constructor

private static final Constructor<CompilerPhase> constructor

Constructor for this compiler phase

PiNodes

public PiNodes(boolean insert)

Create the phase.

Parameters:

insert - If true, we insert PI nodes, If false, we remove them.

PiNodes

public PiNodes(boolean insert,
               boolean typeChecks)

Create the phase.

Parameters:

insert - If true, we insert PI nodes, If false, we remove them.

typeChecks - If true, we insert PI nodes only for type checks.

shouldPerform

public boolean shouldPerform(OptOptions options)

Should this phase be performed? Only perform this when we are doing an SSA-based optimization that can benefit from PI nodes.

Overrides:

shouldPerform in class CompilerPhase

Parameters:

options - controlling compiler options

Returns:

true if the phase should be performed

getClassConstructor

public Constructor<CompilerPhase> getClassConstructor()

Get a constructor object for this compiler phase

Overrides:

getClassConstructor in class CompilerPhase

Returns:

compiler phase constructor

getName

public String getName()

A String representation of this phase

Specified by:

getName in class CompilerPhase

Returns:

a string representation

printingEnabled

public boolean printingEnabled(OptOptions options,
                               boolean before)

Should we print the IR either before or after this phase?

Overrides:

printingEnabled in class CompilerPhase

Parameters:

options - controlling compiler options

before - control for the query

Returns:

true if the IR should be printed, false otherwise.

perform

public void perform(IR ir)

Perform the transformation.

Specified by:

perform in class CompilerPhase

Parameters:

ir - the IR to optimize

insertPiIfNodes

private void insertPiIfNodes(IR ir)

Insert PI nodes corresponding to compare operations. Pi-nodes are represented as dummy assignments with a single argument inserted along each outedge of the conditional.

Parameters:

ir - the governing IR

insertPiBcNodes

private void insertPiBcNodes(IR ir)

Insert Pi nodes for boundchecks.

Each boundcheck Arr, Index will be followed by

 PI Index, Index 

Parameters:

ir - the governing IR

insertPiNullCheckNodes

private void insertPiNullCheckNodes(IR ir)

Insert Pi nodes for null check operations.

Each checkcast obj will be followed by

 PI obj, obj 

Parameters:

ir - the governing IR

insertPiCheckCastNodes

private void insertPiCheckCastNodes(IR ir)

Insert Pi nodes for checkcast operations.

Each checkcast obj will be followed by

 ref_move obj, obj 

Parameters:

ir - the governing IR

cleanUp

static void cleanUp(IR ir)

Change all PI nodes to INT_MOVE instructions

Side effect: invalidates SSA state

Parameters:

ir - the governing IR

getGenerator

public static Instruction getGenerator(Instruction def)

Get the instruction a Pi node is linked to. PRECONDITION: register lists computed and valid.

isNotTakenPi

public static boolean isNotTakenPi(Instruction def)

Is an instruction a Pi node linked to the not taken edge of a conditional branch instruction?

isTakenPi

public static boolean isTakenPi(Instruction def)

Is an instruction a Pi node linked to the taken edge of a conditional branch instruction?

isBoundsCheckPi

public static boolean isBoundsCheckPi(Instruction def)

Is an instruction a Pi node linked to a bounds-check?

isNullCheckPi

public static boolean isNullCheckPi(Instruction def)

Is an instruction a Pi node linked to a null-check?