This file documents the internals of the GNU compilers.

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A GNU Manual

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You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.

Introduction

This manual 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 (WinAVR 20081205) version 4.3.2. The use of the GNU compilers is documented in a separate manual. See Introduction (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 Contributing), the characteristics of the machines supported by GCC as hosts and targets (see Portability), how GCC relates to the ABIs on such systems (see Interface), and the characteristics of the languages for which GCC front ends are written (see Languages). 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.

Additional tutorial information is linked to from http://gcc.gnu.org/readings.html.

• Contributing: How to contribute to testing and developing GCC.
• Portability: Goals of GCC's portability features.
• Interface: Function-call interface of GCC output.
• Libgcc: Low-level runtime library used by GCC.
• Languages: Languages for which GCC front ends are written.
• Source Tree: GCC source tree structure and build system.
• Options: Option specification files.
• Passes: Order of passes, what they do, and what each file is for.
• Trees: The source representation used by the C and C++ front ends.
• RTL: The intermediate representation that most passes work on.
• Control Flow: Maintaining and manipulating the control flow graph.
• Tree SSA: Analysis and optimization of the tree representation.
• Loop Analysis and Representation: Analysis and representation of loops
• Machine Desc: How to write machine description instruction patterns.
• Target Macros: How to write the machine description C macros and functions.
• Host Config: Writing the xm- machine .h file.
• Fragments: Writing the t- target and x- host files.
• Collect2: How collect2 works; how it finds ld.
• Header Dirs: Understanding the standard header file directories.
• Type Information: GCC's memory management; generating type information.
• Funding: How to help assure funding for free software.
• GNU Project: The GNU Project and GNU/Linux.
• Copying: GNU General Public License says how you can copy and share GCC.
• GNU Free Documentation License: How you can copy and share this manual.
• Contributors: People who have contributed to GCC.
• Option Index: Index to command line options.