EDU.purdue.cs.bloat.tbaa

Class TBAA

java.lang.Object

EDU.purdue.cs.bloat.tbaa.TBAA

public class TBAA
extends java.lang.Object

Performs Type-Based Alias Analysis (TBAA) to determine if one expression can alias another. An expression may alias another expression if there is the possibility that they refer to the same location in memory. BLOAT models expressions that may reference memory locations with MemRefExprs. There are two kinds of "access expressions" in Java: field accesses (FieldExpr and StaticFieldExpr) and array references (ArrayRefExpr). Access paths consist of one or more access expressions. For instance, a.b[i].c is an access expression.

TBAA uses the FieldTypeDecl relation to determine whether or not two access paths may refer to the same memory location.

	AP1	AP2	FieldTypeDecl(AP1, Ap2)
p	p	true
p.f	q.g	(f = g) && FieldTypeDecl(p, q)
p.f	q[i]	false
p[i]	q[j]	FieldTypeDecl(p, q)
p	q	TypeDecl(p, q)

The TypeDecl(AP1, AP2) relation is defined as:

Subtypes(Type(AP1)) INTERSECT Subtypes(Type(AP2)) != EMPTY

The subtype relationships are determined by the ClassHierarchy.

See Also:

ClassHierarchy, MemRefExpr, FieldExpr, StaticFieldExpr, ArrayRefExpr

Constructor Summary

Constructors

Constructor and Description
TBAA()

Method Summary

Methods

Modifier and Type	Method and Description
static boolean	canAlias(EditorContext context, Expr a, Expr b) Returns true, if expression a can alias expression b.

Methods inherited from class java.lang.Object

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

Constructor Detail

TBAA

public TBAA()

Method Detail

canAlias

public static boolean canAlias(EditorContext context,
               Expr a,
               Expr b)

Returns true, if expression a can alias expression b.