Package EDU.purdue.cs.bloat.ssa

Class SSA

java.lang.Object

EDU.purdue.cs.bloat.ssa.SSA

public class SSA
extends java.lang.Object

Compute the SSA form of the control flow graph and build FUD chains.

The SSA algorithm is from:

     R. Cytron, J. Ferrante J, B. K. Rosen, M. N. Wegman, and F. K. Zadeck,
     "Efficiently Computing Static Single Assignment Form and the Control
     Dependence Graph", TOPLAS, 13(4): 451-490, October 1991.
 

I made modifications to the algorithm to compute FUD chains and to run the algorithm separately for each variable similar to the SSAPRE algorithm. Making a separate pass for each variable allows variables to be added incrementally.

Field Summary

Fields

Modifier and Type	Field	Description
static boolean	DEBUG

Constructor Summary

Constructors

Constructor	Description
SSA()

Method Summary

Modifier and Type	Method	Description
static void	transform(FlowGraph cfg)	Transforms a control flow graph into Single Static Assignment (SSA) form.
static void	transform(FlowGraph cfg, SSAConstructionInfo info)	Performs the actions necessary to convert a CFG into SSA form with respect to one variable.

Methods inherited from class java.lang.Object

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

Field Detail

DEBUG

public static boolean DEBUG

Constructor Detail

SSA

public SSA()

Method Detail

transform

public static void transform(FlowGraph cfg)

Transforms a control flow graph into Single Static Assignment (SSA) form. First, the CFG is traversed and a list of all variables (both local and stack) eligible for SSA renaming is compiled. Variables are represented by instances of SSAConstructionInfo. Each of these variables is then transformed.

See Also:

transform(FlowGraph), SSAConstructionInfo

transform

public static void transform(FlowGraph cfg,
                             SSAConstructionInfo info)

Performs the actions necessary to convert a CFG into SSA form with respect to one variable. The variable's information is stored in the SSAConstructionInfo.