AN EVALUATION OF AUTOMATIC OBJECT IN-LINE ALLOCATION TECHNIQUES

Object-oriented languages such as Java and Smalltalk provide a uniform object reference model, allowing objects to be conveniently shared. I f implemented directly, these uniform reference models can suffer in e fficiency due to additional memory dereferences and memory management operations. Automatic inline allocation of child objects within parent objects can reduce overheads of heap-allocated pointer-referenced obj ects. We present three compiler analyses to identify inlinable fields by tracking accesses to heap objects. These analyses span a range from local data flow to adaptive whole-program, flow-sensitive inter-proce dural analysis. We measure their cost and effectiveness on a suite of moderate-sized C++ programs (up to 30,000 lines including libraries). We show that aggressive interprocedural analysis is required to enable object inlining, and our adaptive inter-procedural analysis [23] comp utes precise information efficiently. Object inlining eliminates typic ally 40% of object accesses and allocations (improving performance up to 50%). Furthermore,.