EDU.purdue.cs.bloat.diva

Class InductionVarAnalyzer

java.lang.Object

EDU.purdue.cs.bloat.diva.InductionVarAnalyzer

public class InductionVarAnalyzer
extends java.lang.Object

InductionVarAnalyzer traverses a control flow graph and looks for array element swizzle operations inside loops. If possible, these swizzle operations are hoisted out of the loop and are replaced with range swizzle operations. The technique used is Demand-driven Induction Variable Analysis (DIVA).

To accomplish its tasks, InductionVarAnalyzer keeps track of a number of induction variables (represented by Swizzler objects) and local variables.

See Also:

Swizzler, LocalExpr

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	DEBUG

Constructor Summary

Constructors

Constructor and Description
InductionVarAnalyzer()

Method Summary

Methods

Modifier and Type	Method and Description
void	Display_store() Displays (to System.out) all of the Swizzlers stored in the induction variable store.
void	displaySwizzler(Swizzler indswz) Displays the contents of a Swizzler object to System.out.
MemExpr	get_local(int vn) Searchs the stored list of local variables for a local variable with a given value number.
java.lang.Object	get_swizzler(int vn) Searches the list of induction variables for an induction variable with a given value number.
void	insert_aswrange(Swizzler indswz) Adds a swizzle range statement (SRStmt) to the end of each predacessor block of the block containing the phi statement that defines an induction variable provided that the phi block does not dominate its predacessor.
Block	isMu(PhiJoinStmt phi, FlowGraph cfg) Determines whether or not a phi statement is a mu function.
void	transform(FlowGraph cfg) Performs DIVA on a CFG.

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

InductionVarAnalyzer

public InductionVarAnalyzer()

Method Detail

get_swizzler

public java.lang.Object get_swizzler(int vn)

Searches the list of induction variables for an induction variable with a given value number.

Parameters:

vn - Value number to search for.

Returns:

Swizzler object whose target has the desired value number or null, if value number is not found.

get_local

public MemExpr get_local(int vn)

Searchs the stored list of local variables for a local variable with a given value number.

Parameters:

vn - The value number to search for.

Returns:

The local variable with the given value number, or null, if not found.

Display_store

public void Display_store()

Displays (to System.out) all of the Swizzlers stored in the induction variable store.

See Also:

Swizzler

displaySwizzler

public void displaySwizzler(Swizzler indswz)

Displays the contents of a Swizzler object to System.out.

Parameters:

indswz - The Swizzler to display.

insert_aswrange

public void insert_aswrange(Swizzler indswz)

Adds a swizzle range statement (SRStmt) to the end of each predacessor block of the block containing the phi statement that defines an induction variable provided that the phi block does not dominate its predacessor. Phew.

Parameters:

indswz - Swizzler representing the induction variable on which the range swizzle statement is added.

isMu

public Block isMu(PhiJoinStmt phi,
         FlowGraph cfg)

Determines whether or not a phi statement is a mu function. A mu function is a phi function that merges values at loop headers, as opposed to those that occur as a result of forward branching. Mu functions always have two arguments.

Parameters:

phi - phi statement that may be a mu function

cfg - CFG to look through Get rid of this parameter

Returns:

The block containing the mu functions external (that is, outside the loop) argument, also known as the external ssalink. If the phi statement is not a mu function, null is returned.

transform

public void transform(FlowGraph cfg)

Performs DIVA on a CFG.