cetus.transforms
Class IVSubstitution

java.lang.Object
  cetus.transforms.TransformPass
      cetus.transforms.IVSubstitution

public class IVSubstitution
extends TransformPass

IVSubstitution performs induction variable substitution for additive induction variables. The transformation proceeds in two steps, analysis and transformation. The analysis phase detects potential induction variables by matching the statement type that have the following structure. iv = iv+expr, iv = iv-expr iv += expr, iv -= expr iv++, iv--, ++iv, --iv , where expr is either loop-invariant or another induction variable. iv, of course, cannot appear as a defined variable in the loop except for the induction statement. After this matching process, comes a feasibility test that removes any cases where substitution cannot proceed. The transformation phase performs substitution and statement removal depending on the type of each statement. The key enabling functionality of this phase is symbolic summation operation which is provided as a external tool implemented in Symbolic class. TODOs: incorporation with live variable analysis. Algorithms in the CPC09 paper.

Field Summary

Fields inherited from class cetus.transforms.TransformPass

program

Constructor Summary

IVSubstitution(Program program)
Constructs an induction variable transformation pass with the given program object.

Method Summary

java.lang.String	getPassName() Returns the pass name for the transformation.
void	start() Performs the induction variable substitution transformation in two phases.

Methods inherited from class cetus.transforms.TransformPass

run, startAndCheck

Methods inherited from class java.lang.Object

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

Constructor Detail

IVSubstitution

public IVSubstitution(Program program)

Constructs an induction variable transformation pass with the given program object.

Parameters:

program - the input program.

Method Detail

getPassName

public java.lang.String getPassName()

Returns the pass name for the transformation.

Specified by:

getPassName in class TransformPass

Returns:

the pass name.

start

public void start()

Performs the induction variable substitution transformation in two phases. First phase performs analysis to check if the loop is eligible for transformation, and the second phase performs actual transformation if it is allowed.

Specified by:

start in class TransformPass