EDU.purdue.cs.bloat.ssa

Class SSAConstructionInfo

java.lang.Object

EDU.purdue.cs.bloat.ssa.SSAConstructionInfo

public class SSAConstructionInfo
extends java.lang.Object

SSAConstructionInfo contains information needed to convert a CFG into SSA form. Each variable (VarExpr) has an SSAConstructionInfo associated with it. Each SSAConstructionInfo keeps track of information such as the PhiStmts that define copies of the variable, the Blocks in which the variable is defined, and the occurrences (uses) of the variable in both phi and non-phi statements. Note that no PhiStmt is really inserted into a basic block. We just keep track of the mapping. It should also be noted that once a phi statement for a given variable is "inserted" into a block, no other phi statement for that variable is inserted. Thus, the order of insertion determines the precedence of the phi statements: PhiReturnStmt > PhiCatchStmt > PhiJoinStmt.

Additionally, SSAConstruction has methods to insert various flavors of PhiStmts whose targets are the variable associated with the SSAConstruction into Blocks.

See Also:

SSA, PhiStmt, PhiCatchStmt, PhiJoinStmt, PhiReturnStmt

Constructor Summary

Constructors

Constructor and Description
SSAConstructionInfo(FlowGraph cfg, VarExpr expr) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	addCatchPhi(Block block) Inserts a PhiCatchStmt (whose target is the variable represented by this SSAConstructionInfo) into a given Block.
void	addDefBlock(Block block) Makes note of a Block in which the variable is defined by a PhiStmt.
void	addPhi(Block block) Adds a PhiJoinStmt for the variable represented by this SSAConstructionInfo to a given Block.
void	addReal(VarExpr real) Notes a real occurrence (that is, a use that is not an operand to a phi statement) of the variable represented by this SSAConstructionInfo.
void	addRetPhis(Subroutine sub) Adds a PhiReturnStmt to all of the Blocks that are executed upon returning from a given Subroutine.
java.util.Collection	defBlocks() Returns the Blocks containing a definition of the variable represented by this SSAConstruction info.
PhiStmt	phiAtBlock(Block block) Returns the phi statement for the variable represented by this SSAConstructionInfo at a given block in the CFG.
VarExpr	prototype() Returns the program variable associated with this SSAConstructionInfo.
java.util.Collection	reals() Returns all of the real occurrences of this variable.
java.util.Collection	realsAtBlock(Block block) Returns all of the real occurrences of this variable in a given block.
void	removePhiAtBlock(Block block) Removes the phi statement for this variable at a given block.

Methods inherited from class java.lang.Object

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

Constructor Detail

SSAConstructionInfo

public SSAConstructionInfo(FlowGraph cfg,
                   VarExpr expr)

Constructor.

Parameters:

cfg - The control flow graph that is being converted to SSA form.

expr - A variable in the CFG on which SSA analysis is being done.

Method Detail

prototype

public VarExpr prototype()

Returns the program variable associated with this SSAConstructionInfo.

addDefBlock

public void addDefBlock(Block block)

Makes note of a Block in which the variable is defined by a PhiStmt.

phiAtBlock

public PhiStmt phiAtBlock(Block block)

Returns the phi statement for the variable represented by this SSAConstructionInfo at a given block in the CFG.

removePhiAtBlock

public void removePhiAtBlock(Block block)

Removes the phi statement for this variable at a given block.

addPhi

public void addPhi(Block block)

Adds a PhiJoinStmt for the variable represented by this SSAConstructionInfo to a given Block.

addRetPhis

public void addRetPhis(Subroutine sub)

Adds a PhiReturnStmt to all of the Blocks that are executed upon returning from a given Subroutine.

See Also:

PhiReturnStmt, Subroutine.paths

addCatchPhi

public void addCatchPhi(Block block)

Inserts a PhiCatchStmt (whose target is the variable represented by this SSAConstructionInfo) into a given Block.

See Also:

PhiCatchStmt

addReal

public void addReal(VarExpr real)

Notes a real occurrence (that is, a use that is not an operand to a phi statement) of the variable represented by this SSAConstructionInfo.

See Also:

PhiStmt

reals

public java.util.Collection reals()

Returns all of the real occurrences of this variable.

realsAtBlock

public java.util.Collection realsAtBlock(Block block)

Returns all of the real occurrences of this variable in a given block.

defBlocks

public java.util.Collection defBlocks()

Returns the Blocks containing a definition of the variable represented by this SSAConstruction info.