harpoon.Backend.CSAHack.RegAlloc
Class DerivationGenerator

java.lang.Object
  harpoon.Backend.CSAHack.RegAlloc.DerivationGenerator

All Implemented Interfaces:

Derivation, TypeMap

public class DerivationGenerator
extends Object
implements Derivation

DerivationGenerator helps maintain the accuracy of the Derivation while the register allocator creates spills.

Version:

$Id: DerivationGenerator.java,v 1.6 2004/02/08 03:20:48 cananian Exp $

Author:

C. Scott Ananian <cananian@alumni.princeton.edu>

Nested Class Summary

Nested classes/interfaces inherited from interface harpoon.Analysis.Maps.Derivation

Derivation.DList

Nested classes/interfaces inherited from interface harpoon.Analysis.Maps.TypeMap

TypeMap.TypeNotKnownException

Constructor Summary

DerivationGenerator(Instr instrs, Derivation deriv)
Creates a DerivationGenerator.

Method Summary

Derivation.DList	derivation(HCodeElement hce, Temp t) Map compiler temporaries to their derivations.
HClass	typeMap(HCodeElement hce, Temp t) Return the type of a given temporary t, as defined at the definition point hce.

Methods inherited from class java.lang.Object

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

Constructor Detail

DerivationGenerator

public DerivationGenerator(Instr instrs,
                           Derivation deriv)

Creates a DerivationGenerator.

Method Detail

typeMap

public HClass typeMap(HCodeElement hce,
                      Temp t)
               throws TypeMap.TypeNotKnownException

Description copied from interface: TypeMap

Return the type of a given temporary t, as defined at the definition point hce. Iff the type of the temporary is not known, or if hce does not define t, throws TypeNotKnownException. If the temporary represents a derived pointer, null should be returned; in which case the Derivation must return a non-null value. Obviously, TypeMaps for high-level representations without derived pointers should never return null. As a special case, HClass.Void may be returned in low-level IRs to indicate an opaque pointer value which does not correspond to a java object pointer or some derivation thereof --- for example, a pointer into a method dispatch table. The only other time HClass.Void should be returned is for known-null pointer values.

Specified by:

typeMap in interface TypeMap

Parameters:

hce - The HCodeElement defining t.

t - The temporary to examine.

Returns:

the static type of t.

Throws:

TypeMap.TypeNotKnownException - if the TypeMap does not have any information about t as defined at hc.

derivation

public Derivation.DList derivation(HCodeElement hce,
                                   Temp t)
                            throws TypeMap.TypeNotKnownException

Description copied from interface: Derivation

Map compiler temporaries to their derivations.

Specified by:

derivation in interface Derivation

Parameters:

hce - A definition point for t.

t - The temporary to query.

Returns:

null if the temporary has no derivation (is a base pointer, for example), or the derivation otherwise.

Throws:

TypeMap.TypeNotKnownException