IBM XL C++

XL C/C++ is the name of IBM's proprietary optimizing C/C++ compiler for IBM-supported environments.

The IBM XL compilers are built from modularized components consisting of front ends (for different programming languages), a platform agnostic high level optimizer, and platform-specific low-level optimizers/code generators to target specific hardware and operating systems. The XL C/C++ compilers target POWER, BlueGene/Q, and z Systems hardware architectures.

A common high level optimizer across the POWER and z/OS XL C/C++ compilers optimizes the source program using platform-agnostic optimizations such as inter-procedural analysis, profile-directed feedback, and loop and vector optimizations.

A low-level optimizer on each platform performs function-level optimizations, and generates optimized code for a specific operating system and hardware platform.

The particular optimizations performed for any given compilation depend upon the optimization level chosen under option control (O2 to O5) along with any other optimization-related options, such as those for interprocedural analysis or loop optimizations.