Class Hierarchy Graphs, Function Devirtualization, & RTTI

摘要

Function devirtualization is a well-known compiler optimization technique for C++ code. This optimization replaces a call to a virtual method by a call to a particular method of a class, thus eliminating the overheads of accessing a virtual method via virtual table(s). In addition, the direct call may be inlined, leading to higher performance. Class Hierarchy Analysis (CHA) is one of the well-known techniques that are applied to find out whether a virtual call is devirtualizable. CHA is based on constructing the Class Hierarchy Graph (CHG) that encapsulates the base-class-derived class relationship among the classes that use virtual methods.