Unification-based points-to-analysis using multilevel typing

A method for points-to analysis using at least three levels of subtyping in an optimizing compiler, comprising:

• assigning a first location type to one of a variable and an expression in a computer program;
• assigning a reader component to a data constructor associated with the first location type, whereby the reader component has a second location type;
• and
• assigning a writer component to a data constructor associated with the first location type, whereby the writer component has a third location type.

An apparatus for performing points-to analysis, comprising:

• means for assigning a first location type to one of a variable and an expression in a computer program;
• means for assigning a reader component to a data constructor associated with the first location type, whereby the reader component has a second location type;
• and
• means for assigning a writer component to the data constructor associated with the first location type, whereby the writer component has a third location type.

A computer-readable medium having a data structure for defining location types for representing sets of memory locations, the computer-readable medium comprising:

• a data constructor;
• wherein the data constructor is associated with a first location type, and wherein the data constructor comprises:
• a reader component that has an associated second location type;
• and
• a writer component that has an associated third location type.

A computer system having a data structure for defining location types for representing sets of memory locations, the computer system comprising:

• a data constructor;
• wherein the data constructor is associated with a first location type, and wherein the data constructor comprises:
• a reader component that has an associated second location type;
• and
• a writer component that has an associated third location type.