GCC 8.0 GNU Compiler Collection Internals documents the internals of the GNU compilers, including how to port them to new targets and some information about how to write front ends for new languages. It corresponds to the compilers (GCC) version 8.0.1. The use of the GNU compilers is documented in a separate manual. See Section "Introduction" in Using the GNU Compiler Collection (GCC).This manual is mainly a reference manual rather than a tutorial. It discusses how to contribute to GCC (see Chapter 1 [Contributing], page 3), the characteristics of the machines supported by GCC as hosts and targets (see Chapter 2 [Portability], page 5), how GCC relates to the ABIs on such systems (see Chapter 3 [Interface], page 7), and the characteristics of the languages for which GCC front ends are written (see Chapter 5 [Languages], page 59). It then describes the GCC source tree structure and build system, some of the interfaces to GCC front ends, and how support for a target system is implemented in GCC.This manual is available online for free at gnu.org. This manual is printed in grayscale.