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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 (AVR_8_bit_GNU_Toolchain_3.6.2_1778) version 5.4.0. The use of the GNU compilers is documented in a separate manual. See Introduction.

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.
• Testsuites: GCC testsuites.
• Options: Option specification files.
• Passes: Order of passes, what they do, and what each file is for.
• GENERIC: Language-independent representation generated by Front Ends
• GIMPLE: Tuple representation used by Tree SSA optimizers
• Tree SSA: Analysis and optimization of GIMPLE
• RTL: Machine-dependent low-level intermediate representation.
• Control Flow: Maintaining and manipulating the control flow graph.
• 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.
• Plugins: Extending the compiler with plugins.
• LTO: Using Link-Time Optimization.
• Match and Simplify: How to write expression simplification patterns for GIMPLE and GENERIC
• 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.
• Concept Index: Index of concepts and symbol names.