Compiling with IPA

If you request Interprocedural Analysis (IPA) through the IPA compiler option, the compilation process changes significantly. IPA instructs the compiler to optimize your z/OS® XL C/C++ program across compilation units, and to perform optimizations that are not otherwise available with the z/OS XL C/C++ compiler. You should refer to z/OS XL C/C++ Programming Guide for an overview of IPA processing before you invoke the compiler with the IPA compiler option.

Differences between the IPA compilation process and the regular compilation process are noted throughout this topic.

Figure 1 shows the flow of processing for a regular compilation:

IPA processing consists of two separate steps, called the IPA compile step and the IPA link step.