com.android.dx.ssa

Class SsaBasicBlock

java.lang.Object

com.android.dx.ssa.SsaBasicBlock

public final class SsaBasicBlock
extends Object

An SSA representation of a basic block.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SsaBasicBlock.LabelComparator Label comparator.
static interface	SsaBasicBlock.Visitor Visitor interface for basic blocks.

Field Summary

Fields

Modifier and Type	Field and Description
static Comparator<SsaBasicBlock>	LABEL_COMPARATOR non-null; comparator for instances of this class that just compares block labels

Constructor Summary

Constructors

Constructor and Description
SsaBasicBlock(int basicBlockIndex, int ropLabel, SsaMethod parent) Creates a new empty basic block.

Method Summary

Methods

Modifier and Type	Method and Description
void	addDomChild(SsaBasicBlock child) Adds a basic block as a dom child for this block.
void	addInsnToHead(Insn insn) Adds an insn to the head of this basic block, just after any phi insns.
void	addLiveIn(int regV) Adds regV to the live-in list for this block.
void	addLiveOut(int regV) Adds regV to the live-out list for this block.
void	addMoveToBeginning(RegisterSpec result, RegisterSpec source) Adds a move instruction after the phi insn block.
void	addMoveToEnd(RegisterSpec result, RegisterSpec source) Adds a move instruction to the end of this basic block, just before the last instruction.
void	addPhiInsnForReg(int reg) Adds a phi insn to the beginning of this block.
void	addPhiInsnForReg(RegisterSpec resultSpec) Adds a phi insn to the beginning of this block.
void	exitBlockFixup(SsaBasicBlock exitBlock) Attaches block to an exit block if necessary.
void	forEachInsn(SsaInsn.Visitor visitor) Visits all insns in this block.
void	forEachPhiInsn(PhiInsn.Visitor v) Visits each phi insn.
ArrayList<SsaBasicBlock>	getDomChildren() Gets the dom children for this node.
int	getIndex()
ArrayList<SsaInsn>	getInsns()
IntSet	getLiveInRegs() Returns the set of live-in registers.
IntSet	getLiveOutRegs() Returns the set of live-out registers.
SsaMethod	getParent()
List<SsaInsn>	getPhiInsns()
BitSet	getPredecessors()
SsaBasicBlock	getPrimarySuccessor()
int	getPrimarySuccessorIndex()
int	getPrimarySuccessorRopLabel()
int	getRopLabel()
String	getRopLabelString()
IntList	getRopLabelSuccessorList()
IntList	getSuccessorList()
BitSet	getSuccessors()
SsaBasicBlock	insertNewPredecessor() Inserts a new empty GOTO block as a predecessor to this block.
SsaBasicBlock	insertNewSuccessor(SsaBasicBlock other) Constructs and inserts a new empty GOTO block Z between this block (A) and a current successor block (B).
boolean	isExitBlock()
boolean	isReachable() Returns true if this block was last calculated to be reachable.
static SsaBasicBlock	newFromRop(RopMethod rmeth, int basicBlockIndex, SsaMethod parent) Creates a new SSA basic block from a ROP form basic block.
void	removeAllPhiInsns() Deletes all phi insns.
void	removeSuccessor(int oldIndex) Removes a successor from this block's successor list.
void	replaceLastInsn(Insn insn) Replaces the last insn in this block.
void	replaceSuccessor(int oldIndex, int newIndex) Replaces an old successor with a new successor.
void	scheduleMovesFromPhis() Sorts move instructions added via addMoveToEnd during phi removal so that results don't overwrite sources that are used.
void	setReachable(int reach) Sets reachability of block to specified value
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

LABEL_COMPARATOR

public static final Comparator<SsaBasicBlock> LABEL_COMPARATOR

non-null; comparator for instances of this class that just compares block labels

Constructor Detail

SsaBasicBlock

public SsaBasicBlock(int basicBlockIndex,
             int ropLabel,
             SsaMethod parent)

Creates a new empty basic block.

Parameters:

basicBlockIndex - index this block will have

ropLabel - original rop-form label

parent - method of this block

Method Detail

newFromRop

public static SsaBasicBlock newFromRop(RopMethod rmeth,
                       int basicBlockIndex,
                       SsaMethod parent)

Creates a new SSA basic block from a ROP form basic block.

Parameters:

rmeth - original method

basicBlockIndex - index this block will have

parent - method of this block predecessor set will be updated

Returns:

new instance

addDomChild

public void addDomChild(SsaBasicBlock child)

Adds a basic block as a dom child for this block. Used when constructing the dom tree.

Parameters:

child - non-null; new dom child

getDomChildren

public ArrayList<SsaBasicBlock> getDomChildren()

Gets the dom children for this node. Don't modify this list.

Returns:

non-null; list of dom children

addPhiInsnForReg

public void addPhiInsnForReg(int reg)

Adds a phi insn to the beginning of this block. The result type of the phi will be set to void, to indicate that it's currently unknown.

Parameters:

reg - >=0; result reg

addPhiInsnForReg

public void addPhiInsnForReg(RegisterSpec resultSpec)

Adds a phi insn to the beginning of this block. This is to be used when the result type or local-association can be determined at phi insert time.

Parameters:

resultSpec - non-null; reg

addInsnToHead

public void addInsnToHead(Insn insn)

Adds an insn to the head of this basic block, just after any phi insns.

Parameters:

insn - non-null; rop-form insn to add

replaceLastInsn

public void replaceLastInsn(Insn insn)

Replaces the last insn in this block. The provided insn must have some branchingness.

Parameters:

insn - non-null; rop-form insn to add, which must branch.

forEachPhiInsn

public void forEachPhiInsn(PhiInsn.Visitor v)

Visits each phi insn.

Parameters:

v - non-null; the callback

removeAllPhiInsns

public void removeAllPhiInsns()

Deletes all phi insns. Do this after adding appropriate move insns.

getInsns

public ArrayList<SsaInsn> getInsns()

Returns:

non-null; the (mutable) instruction list for this block, with phi insns at the beginning

getPhiInsns

public List<SsaInsn> getPhiInsns()

Returns:

non-null; the (mutable) list of phi insns for this block

getIndex

public int getIndex()

Returns:

the block index of this block

getRopLabel

public int getRopLabel()

Returns:

the label of this block in rop form

getRopLabelString

public String getRopLabelString()

Returns:

the label of this block in rop form as a hex string

getPredecessors

public BitSet getPredecessors()

Returns:

non-null; predecessors set, indexed by block index

getSuccessors

public BitSet getSuccessors()

Returns:

non-null; successors set, indexed by block index

getSuccessorList

public IntList getSuccessorList()

Returns:

non-null; ordered successor list, containing block indicies

getPrimarySuccessorIndex

public int getPrimarySuccessorIndex()

Returns:

>= -1; block index of primary successor or -1 if no primary successor

getPrimarySuccessorRopLabel

public int getPrimarySuccessorRopLabel()

Returns:

rop label of primary successor

getPrimarySuccessor

public SsaBasicBlock getPrimarySuccessor()

Returns:

null-ok; the primary successor block or null if there is none

getRopLabelSuccessorList

public IntList getRopLabelSuccessorList()

Returns:

successor list of rop labels

getParent

public SsaMethod getParent()

Returns:

non-null; method that contains this block

insertNewPredecessor

public SsaBasicBlock insertNewPredecessor()

Inserts a new empty GOTO block as a predecessor to this block. All previous predecessors will be predecessors to the new block.

Returns:

non-null; an appropriately-constructed instance

insertNewSuccessor

public SsaBasicBlock insertNewSuccessor(SsaBasicBlock other)

Constructs and inserts a new empty GOTO block Z between this block (A) and a current successor block (B). The new block will replace B as A's successor and A as B's predecessor. A and B will no longer be directly connected. If B is listed as a successor multiple times, all references are replaced.

Parameters:

other - current successor (B)

Returns:

non-null; an appropriately-constructed instance

replaceSuccessor

public void replaceSuccessor(int oldIndex,
                    int newIndex)

Replaces an old successor with a new successor. This will throw RuntimeException if oldIndex was not a successor.

Parameters:

oldIndex - index of old successor block

newIndex - index of new successor block

removeSuccessor

public void removeSuccessor(int oldIndex)

Removes a successor from this block's successor list.

Parameters:

oldIndex - index of successor block to remove

exitBlockFixup

public void exitBlockFixup(SsaBasicBlock exitBlock)

Attaches block to an exit block if necessary. If this block is not an exit predecessor or is the exit block, this block does nothing. For use by SsaMethod.makeExitBlock()

Parameters:

exitBlock - non-null; exit block

addMoveToEnd

public void addMoveToEnd(RegisterSpec result,
                RegisterSpec source)

Adds a move instruction to the end of this basic block, just before the last instruction. If the result of the final instruction is the source in question, then the move is placed at the beginning of the primary successor block. This is for unversioned registers.

Parameters:

result - move destination

source - move source

addMoveToBeginning

public void addMoveToBeginning(RegisterSpec result,
                      RegisterSpec source)

Adds a move instruction after the phi insn block.

Parameters:

result - move destination

source - move source

addLiveOut

public void addLiveOut(int regV)

Adds regV to the live-out list for this block. This is called by the liveness analyzer.

Parameters:

regV - register that is live-out for this block.

addLiveIn

public void addLiveIn(int regV)

Adds regV to the live-in list for this block. This is called by the liveness analyzer.

Parameters:

regV - register that is live-in for this block.

getLiveInRegs

public IntSet getLiveInRegs()

Returns the set of live-in registers. Valid after register interference graph has been generated, otherwise empty.

Returns:

non-null; live-in register set.

getLiveOutRegs

public IntSet getLiveOutRegs()

Returns the set of live-out registers. Valid after register interference graph has been generated, otherwise empty.

Returns:

non-null; live-out register set

isExitBlock

public boolean isExitBlock()

Returns:

true if this is the one-and-only exit block for this method

isReachable

public boolean isReachable()

Returns true if this block was last calculated to be reachable. Recalculates reachability if value has never been computed.

Returns:

true if reachable

setReachable

public void setReachable(int reach)

Sets reachability of block to specified value

Parameters:

reach - new value of reachability for block

scheduleMovesFromPhis

public void scheduleMovesFromPhis()

Sorts move instructions added via addMoveToEnd during phi removal so that results don't overwrite sources that are used. For use after all phis have been removed and all calls to addMoveToEnd() have been made.

This is necessary because copy-propogation may have left us in a state where the same basic block has the same register as a phi operand and a result. In this case, the register in the phi operand always refers value before any other phis have executed.

forEachInsn

public void forEachInsn(SsaInsn.Visitor visitor)

Visits all insns in this block.

Parameters:

visitor - non-null; callback interface

toString

public String toString()

Overrides:

toString in class Object