Automatic Precompiled Headers: Speeding up C++ Application Build Times

This paper describes the crucial design and implementation issues that arise in building a fully automatic precompiled header mechanism for compiling industrial-strength C and C++ applications. The key challenges include designing the Makefile-transparent automation, determining the precompile-able region, capturing the compile environment and verifying it and addressing the correctness issues involved in using precompiled headers. The ensuing discussion treats the internals of the actual dumping and loading of precompiled headers as a black-box beyond a brief high-level description. An automatic precompiled header mechanism has been implemented in aCC, the HP ANSI C++ compiler, and the results of compiling real applications show that it achieves significant speedup in compile-times of real applications.