scale.clef.decl
Class VariableDecl

java.lang.Object
  scale.common.Root
      scale.clef.Node
          scale.clef.decl.Declaration
              scale.clef.decl.ValueDecl
                  scale.clef.decl.VariableDecl

All Implemented Interfaces:

java.lang.Comparable, AnnotationInterface, DisplayNode

Direct Known Subclasses:

EquivalenceDecl, FormalDecl, RenamedVariableDecl, VirtualVar

public class VariableDecl
extends ValueDecl

This class declares a variable.

$Id: VariableDecl.java,v 1.103 2007-08-28 13:34:32 burrill Exp $

Copyright 2008 by the Scale Compiler Group,
Department of Computer Science
University of Massachusetts,
Amherst MA. 01003, USA
All Rights Reserved.

If you want to name your generated variables _inxxx where xxx is a number you would do

   UniqueName un = new UniqueName("_in");
   ...
   VariableDecl vd = new VariableDecl(un.genName(), type);
   vd.setTemporary();
   ...
 

If you don't care about the name just do

   VariableDecl vd = new VariableDecl(type);
 

The naming scheme is basically _oonnn where oo identifies the optimization that created the variable. Compiler created variables should be temporary variables unless they must reside in memory. Some values in use for oo are

oo	creater	use
A	parser	Function prototype argument names
V	parser	Compiler created variables
_t	FindAliases	Compiler created temporary alias variables
vv	Aliases	Compiler created temporary alias virtual variables
rv_	Aliases	Compiler created temporary alias variables
addrtaken_	Aliases	Compiler created temporary alias variables
s	Scribble	Compiler created temporary variables
vn	ValNum	Compiler created temporary variables
li	LICM	Compiler created temporary variables
sr	ScalarReplacement	Compiler created temporary variables
np	frontend	Compiler created temporary variables
cs	Clef2Scribble	Compiler created temporary variables

See Also:

UniqueName

Field Summary

static boolean

ignoreAddressTaken Set this flag true to study the effect of the address-taken attribute.

Constructor Summary

VariableDecl(java.lang.String name, Type type)
Create a variable declaration which doesn't have a default value.

VariableDecl(java.lang.String name, Type type, Expression initialValue)

Method Summary

boolean	addressTaken() Return true if the address of this Declaration has been taken.
protected void	computeAttributes() Determine how the variable must be handled.
Declaration	copy(java.lang.String name) Return a copy of this Declaration but with a different name.
void	declareFtnResultVar() Specify that the variable is declared as the result variable of a function.
int	getAddressRegister() Return the register the code generator assigned to the address of this variable.
Literal	getConstantValue() Return the constant value of the expression.
Displacement	getDisplacement() Return the displacement the code generator assigned to this variable.
Expression	getInitialValue() Return the initializer for this variable or null.
VariableDecl	getOriginal() Return the variable that this variable was renamed from.
Assigned	getStorageLoc() Return the location type used for this declaration.
int	getValueRegister() Return the register the code generator assigned to this variable.
boolean	hasHiddenAliases() Return true if the variable may be modified in an unknown way.
boolean	hasHiddenPtrAliases() Return true if the memory, to which this pointer variable refers, may be modified in an unknown way.
boolean	hasInvalidArrayReferences() Return true if the array specified by this variable has invalid array references.
boolean	inMemory() Return true if this declaration is to be allocated to memory.
boolean	isCommonBaseVar() Return true if the variable is the base variable for Fortran COMMON.
boolean	isCommonBaseVariable() Return true if this is the base variable of a Fortran COMMON area.
boolean	isConst() Return true if the variable is a const variable.
boolean	isFtnResultVar() Return true if the declaration is declared as the result variable of a function.
boolean	isNotAliasCandidate() Return true if no aliases should be created for this variable.
boolean	isNotSSACandidate() Return true if this variable can not be in SSA form.
boolean	isReferenced() Return true if the declaration is referenced somewhere in the Clef AST.
boolean	isRestricted() Return true if the type specifies restricted.
boolean	isStatic() Return true if this declaration is static.
protected boolean	isStorageLocSet() Return true if the location type used for this declaration is known.
boolean	isTemporary() Return true if the declaration is a temporary variable.
boolean	isVariableDecl() Return true if VariableDecl instance.
boolean	isVolatile() Return true if the type specifies volatile.
boolean	optimizationCandidate() Return true if this variable is not a global variable, is not an atomic type, is not volatile, is not const, has no hidden alias, does not have its address taken, and does not have an initial value.
Residency	residency() Return the declaration residency.
VariableDecl	returnVariableDecl() Return a VariableDecl instance or null.
void	setAddressRegister(int reg) Specify the register the code generator assigned to the address of this variable.
void	setAddressTaken() Record that the address is used.
void	setDisplacement(Displacement disp) Specify the displacement the code generator assigned to this variable.
void	setHiddenAliases() Specify that the variable may be modified in an unknown way.
void	setHiddenPtrAliases() Specify that the memory, to which this pointer variable refers, may be modified in an unknown way.
void	setInitialValue(Expression value) Specify the initial value for a variable.
void	setInvalidArrayReferences() Record that the array specified by this variable has invalid array references.
void	setReferenced() Specify that the variable is referenced somewhere in the Clef AST.
void	setResidency(Residency residency) Specify the residency of the declaration.
void	setStorageLoc(Assigned loc) Set the location type used for this declaration.
void	setTemporary() Specify that the variable is a temporary variable.
void	setType(Type type) Specify the type of this declaration.
void	setValue(Expression value) Specify the initial value for a variable.
void	setValueRegister(int reg, ResultMode mode) Specify the register the code generator temporarily assigned to this variable.
void	setVisibility(Visibility visibility) Specify the visibility of the declaration.
boolean	shouldBeInRegister() Return true if this variable should be allocated to a register.
void	specifyCommonBaseVariable() Specify that this variable is the base variable for a Fortram COMMON.
java.lang.String	toStringSpecial() This method allows sub-classes to provide class specific stuff to the string.
ResultMode	valueRegMode() Return the register mode that the code generator temporarily assigned to this variable.
void	visit(Predicate p) Process a node by calling its associated routine.

Methods inherited from class scale.clef.decl.ValueDecl

getChild, getValue, isValueDecl, numChildren, returnValueDecl

Methods inherited from class scale.clef.decl.Declaration

accessibility, compareTo, getActualType, getAlias, getCoreType, getDecl, getDisplayColorHint, getDisplayLabel, getDisplayShapeHint, getMode, getName, getPointedToCore, getTag, getType, hashCode, isCaseLabelDecl, isEnumElementDecl, isEquivalenceDecl, isExceptionDecl, isFieldDecl, isFileDecl, isFormalDecl, isForwardProcedureDecl, isGlobal, isLabelDecl, isProcedureDecl, isPure, isRenamed, isRenamedVariableDecl, isRoutineDecl, isStmtFtnDecl, isTypeDecl, isTypeName, isUnknownFormals, isVirtual, isWeak, returnCaseLabelDecl, returnEnumElementDecl, returnEquivalenceDecl, returnExceptionDecl, returnFieldDecl, returnFileDecl, returnFormalDecl, returnForwardProcedureDecl, returnLabelDecl, returnProcedureDecl, returnRenamedVariableDecl, returnRoutineDecl, returnStmtFtnDecl, returnTypeDecl, returnTypeName, returnUnknownFormals, setAccessibility, setAlias, setName, setTag, setWeak, visibility

Methods inherited from class scale.clef.Node

getSourceLineNumber, setAnnotationLevel, setReportLevel, setSourceLineNumber, toString, toString, toStringChildren

Methods inherited from class scale.common.Root

addAnnotation, allAnnotations, allMatchingAnnotations, getAnnotation, getDisplayName, getDisplayString, getNodeCount, getNodeID, hasAnnotation, hasEqualAnnotation, removeAnnotation, removeAnnotations, toStringAnnotations, toStringClass, trace, trace, trace

Methods inherited from class java.lang.Object

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

Field Detail

ignoreAddressTaken

public static boolean ignoreAddressTaken

Set this flag true to study the effect of the address-taken attribute. Note, when this flag is set true programs will not be compiled correctly.

Constructor Detail

VariableDecl

public VariableDecl(java.lang.String name,
                    Type type,
                    Expression initialValue)

VariableDecl

public VariableDecl(java.lang.String name,
                    Type type)

Create a variable declaration which doesn't have a default value.

Method Detail

setType

public void setType(Type type)

Description copied from class: Declaration

Specify the type of this declaration.

Overrides:

setType in class Declaration

setVisibility

public void setVisibility(Visibility visibility)

Specify the visibility of the declaration.

Overrides:

setVisibility in class Declaration

Parameters:

visibility - is the visibility of the declaration

See Also:

Visibility

setResidency

public void setResidency(Residency residency)

Specify the residency of the declaration.

Overrides:

setResidency in class Declaration

Parameters:

residency - is the residency of the declaration

See Also:

Residency

residency

public Residency residency()

Return the declaration residency.

Overrides:

residency in class Declaration

See Also:

Residency

isStorageLocSet

protected final boolean isStorageLocSet()

Return true if the location type used for this declaration is known.

getStorageLoc

public Assigned getStorageLoc()

Return the location type used for this declaration. If the location type has not yet been decided, this routine determines where the variable should be located. Variables whose residency is memory, whose visibility is not local, or that have an initial value are assigned to memory. Variables whose address is taken or that can not be assigned to a register, are allocated to the stack.

Overrides:

getStorageLoc in class Declaration

See Also:

setStorageLoc(scale.clef.decl.Assigned), Machine.keepTypeInRegister(scale.clef.type.Type, boolean)

setStorageLoc

public final void setStorageLoc(Assigned loc)

Set the location type used for this declaration.

Overrides:

setStorageLoc in class Declaration

inMemory

public boolean inMemory()

Return true if this declaration is to be allocated to memory.

Overrides:

inMemory in class Declaration

getDisplacement

public final Displacement getDisplacement()

Return the displacement the code generator assigned to this variable.

Overrides:

getDisplacement in class Declaration

setDisplacement

public final void setDisplacement(Displacement disp)

Specify the displacement the code generator assigned to this variable.

Overrides:

setDisplacement in class Declaration

getValueRegister

public final int getValueRegister()

Return the register the code generator assigned to this variable.

Overrides:

getValueRegister in class Declaration

valueRegMode

public final ResultMode valueRegMode()

Return the register mode that the code generator temporarily assigned to this variable.

Overrides:

valueRegMode in class Declaration

See Also:

Generator

setValueRegister

public final void setValueRegister(int reg,
                                   ResultMode mode)

Specify the register the code generator temporarily assigned to this variable.

Overrides:

setValueRegister in class Declaration

See Also:

Generator

getAddressRegister

public final int getAddressRegister()

Return the register the code generator assigned to the address of this variable.

Overrides:

getAddressRegister in class Declaration

setAddressRegister

public final void setAddressRegister(int reg)

Specify the register the code generator assigned to the address of this variable.

Overrides:

setAddressRegister in class Declaration

isReferenced

public boolean isReferenced()

Return true if the declaration is referenced somewhere in the Clef AST.

Overrides:

isReferenced in class Declaration

See Also:

VariableDecl, RoutineDecl

setReferenced

public final void setReferenced()

Specify that the variable is referenced somewhere in the Clef AST.

Overrides:

setReferenced in class Declaration

See Also:

VariableDecl, RoutineDecl

isConst

public boolean isConst()

Return true if the variable is a const variable.

Overrides:

isConst in class ValueDecl

isTemporary

public final boolean isTemporary()

Return true if the declaration is a temporary variable.

Overrides:

isTemporary in class Declaration

setTemporary

public final void setTemporary()

Specify that the variable is a temporary variable.

hasHiddenAliases

public boolean hasHiddenAliases()

Return true if the variable may be modified in an unknown way.

Overrides:

hasHiddenAliases in class Declaration

setHiddenAliases

public final void setHiddenAliases()

Specify that the variable may be modified in an unknown way.

hasHiddenPtrAliases

public boolean hasHiddenPtrAliases()

Return true if the memory, to which this pointer variable refers, may be modified in an unknown way.

setHiddenPtrAliases

public final void setHiddenPtrAliases()

Specify that the memory, to which this pointer variable refers, may be modified in an unknown way.

isFtnResultVar

public final boolean isFtnResultVar()

Return true if the declaration is declared as the result variable of a function.

Overrides:

isFtnResultVar in class Declaration

declareFtnResultVar

public final void declareFtnResultVar()

Specify that the variable is declared as the result variable of a function.

setAddressTaken

public final void setAddressTaken()

Record that the address is used.

Overrides:

setAddressTaken in class Declaration

addressTaken

public boolean addressTaken()

Return true if the address of this Declaration has been taken.

Overrides:

addressTaken in class Declaration

specifyCommonBaseVariable

public final void specifyCommonBaseVariable()

Specify that this variable is the base variable for a Fortram COMMON.

isCommonBaseVariable

public final boolean isCommonBaseVariable()

Return true if this is the base variable of a Fortran COMMON area.

Overrides:

isCommonBaseVariable in class Declaration

setInvalidArrayReferences

public final void setInvalidArrayReferences()

Record that the array specified by this variable has invalid array references. An example of an invalid array reference is something like

    ((int) ((char *) a + 14))[5]
 

hasInvalidArrayReferences

public final boolean hasInvalidArrayReferences()

Return true if the array specified by this variable has invalid array references. An example of an invalid array reference is something like

    ((int) ((char *) a + 14))[5]
 

computeAttributes

protected final void computeAttributes()

Determine how the variable must be handled. There seems to be some redundancy involved but we will leave the resolution to some future date. It is true that if the variable is an optimization candidate, then it must be able to be put in SSA form.

isNotSSACandidate

public final boolean isNotSSACandidate()

Return true if this variable can not be in SSA form. A variable cannot be put in SSA form if

• it is not an atomic type (e.g., an array or struct),
• its address is taken,
• it is volatile,
• it is a global variable, or
• it has hidden aliases.

Also, there is no need to place const variables in SSA form.

isNotAliasCandidate

public final boolean isNotAliasCandidate()

Return true if no aliases should be created for this variable. An aliases should not be created if this variable

• resides in memory,
• is global,
• has its address taken,
• has hidden aliases,
• is referenced indirectly, or
• is not an atomic type (e.g., an array or struct).

An "alias" is usually created by using a copy of the variable that is maintained in a register.

shouldBeInRegister

public final boolean shouldBeInRegister()

Return true if this variable should be allocated to a register. A variable can not be allocated to a register if

• it is global,
• it is not an atomic type,
• its address is taken,
• it is volatile,
• it is allocted to memory, or
• it has an initial value.

optimizationCandidate

public final boolean optimizationCandidate()

Return true if this variable

• is not a global variable,
• is not an atomic type,
• is not volatile,
• is not const,
• has no hidden alias,
• does not have its address taken, and
• does not have an initial value.

isVolatile

public final boolean isVolatile()

Return true if the type specifies volatile.

isRestricted

public final boolean isRestricted()

Return true if the type specifies restricted.

visit

public void visit(Predicate p)

Description copied from class: Node

Process a node by calling its associated routine. See the "visitor" design pattern in Design Patterns: Elements of Reusable Object-Oriented Software by E. Gamma, et al, Addison Wesley, ISBN 0-201-63361-2.

Each class has a visit(Predicate p) method. For example, in class ABC:

   public void visit(Predicate p)
   {
     p.visitABC(this);
   }
 

and the class that implements Predicate has a method

   public void visitABC(Node n)
   {
     ABC a = (ABC) n;
     ...
   }
 

Thus, the class that implements Predicate can call

   n.visit(this);
 

where n is a Node sub-class without determining which specific sub-class n is. The visit pattern basically avoids implementing a large switch statement or defining different methods in each class for some purpose.

Overrides:

visit in class ValueDecl

See Also:

Predicate

getInitialValue

public final Expression getInitialValue()

Return the initializer for this variable or null.

setInitialValue

public final void setInitialValue(Expression value)

Specify the initial value for a variable. This method is used in those cases where the variable must be defined before its initial value is known.

setValue

public final void setValue(Expression value)

Specify the initial value for a variable. This method is used in those cases where the variable must be defined before its initial value is known.

Overrides:

setValue in class ValueDecl

getConstantValue

public Literal getConstantValue()

Return the constant value of the expression.

Overrides:

getConstantValue in class ValueDecl

See Also:

Lattice

isStatic

public final boolean isStatic()

Return true if this declaration is static.

getOriginal

public VariableDecl getOriginal()

Return the variable that this variable was renamed from.

toStringSpecial

public java.lang.String toStringSpecial()

Description copied from class: Node

This method allows sub-classes to provide class specific stuff to the string.

Overrides:

toStringSpecial in class Declaration

copy

public Declaration copy(java.lang.String name)

Return a copy of this Declaration but with a different name.

Specified by:

copy in class Declaration

isCommonBaseVar

public final boolean isCommonBaseVar()

Return true if the variable is the base variable for Fortran COMMON.

isVariableDecl

public final boolean isVariableDecl()

Description copied from class: Declaration

Return true if VariableDecl instance.

Overrides:

isVariableDecl in class Declaration

returnVariableDecl

public final VariableDecl returnVariableDecl()

Description copied from class: Declaration

Return a VariableDecl instance or null.

Overrides:

returnVariableDecl in class Declaration