Using the GNU Compiler Collection For gcc version 6.1.0 (GCC) Richard M. Stallman and the GCC Developer Community Published by: GNU Press Website: http://www.gnupress.org a division of the General: [email protected] Free Software Foundation Orders: [email protected] 51 Franklin Street, Fifth Floor Tel 617-542-5942 Boston, MA 02110-1301 USA Fax 617-542-2652 Last printed October 2003 for GCC 3.3.1. Printed copies are available for $45 each. Copyright c 1988-2016 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being \Funding Free Software", the Front-Cover Texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the section entitled \GNU Free Documentation License". (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: 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. i Short Contents Introduction ::::::::::::::::::::::::::::::::::::::::::::: 1 1 Programming Languages Supported by GCC ::::::::::::::: 3 2 Language Standards Supported by GCC :::::::::::::::::: 5 3 GCC Command Options ::::::::::::::::::::::::::::::: 9 4 C Implementation-Defined Behavior :::::::::::::::::::: 373 5 C++ Implementation-Defined Behavior ::::::::::::::::: 381 6 Extensions to the C Language Family ::::::::::::::::::: 383 7 Extensions to the C++ Language :::::::::::::::::::::: 681 8 GNU Objective-C Features ::::::::::::::::::::::::::: 697 9 Binary Compatibility :::::::::::::::::::::::::::::::: 713 10 gcov|a Test Coverage Program ::::::::::::::::::::::: 717 11 gcov-tool|an Offline Gcda Profile Processing Tool ::::::: 727 12 Known Causes of Trouble with GCC :::::::::::::::::::: 731 13 Reporting Bugs ::::::::::::::::::::::::::::::::::::: 747 14 How To Get Help with GCC :::::::::::::::::::::::::: 749 15 Contributing to GCC Development ::::::::::::::::::::: 751 Funding Free Software ::::::::::::::::::::::::::::::::::: 753 The GNU Project and GNU/Linux::::::::::::::::::::::::: 755 GNU General Public License :::::::::::::::::::::::::::::: 757 GNU Free Documentation License ::::::::::::::::::::::::: 769 Contributors to GCC :::::::::::::::::::::::::::::::::::: 777 Option Index :::::::::::::::::::::::::::::::::::::::::: 795 Keyword Index ::::::::::::::::::::::::::::::::::::::::: 819 iii Table of Contents Introduction :::::::::::::::::::::::::::::::::::::::: 1 1 Programming Languages Supported by GCC ::::::::::::::::::::::::::::::::::::::::::::::::: 3 2 Language Standards Supported by GCC ::::: 5 2.1 C Language :::::::::::::::::::::::::::::::::::::::::::::::::::: 5 2.2 C++ Language :::::::::::::::::::::::::::::::::::::::::::::::: 6 2.3 Objective-C and Objective-C++ Languages :::::::::::::::::::: 7 2.4 Go Language::::::::::::::::::::::::::::::::::::::::::::::::::: 8 2.5 References for Other Languages :::::::::::::::::::::::::::::::: 8 3 GCC Command Options ::::::::::::::::::::::: 9 3.1 Option Summary::::::::::::::::::::::::::::::::::::::::::::::: 9 3.2 Options Controlling the Kind of Output ::::::::::::::::::::::: 27 3.3 Compiling C++ Programs :::::::::::::::::::::::::::::::::::: 32 3.4 Options Controlling C Dialect ::::::::::::::::::::::::::::::::: 33 3.5 Options Controlling C++ Dialect ::::::::::::::::::::::::::::: 39 3.6 Options Controlling Objective-C and Objective-C++ Dialects :: 51 3.7 Options to Control Diagnostic Messages Formatting ::::::::::: 55 3.8 Options to Request or Suppress Warnings ::::::::::::::::::::: 56 3.9 Options for Debugging Your Program ::::::::::::::::::::::::: 88 3.10 Options That Control Optimization :::::::::::::::::::::::::: 93 3.11 Program Instrumentation Options::::::::::::::::::::::::::: 148 3.12 Options Controlling the Preprocessor:::::::::::::::::::::::: 159 3.13 Passing Options to the Assembler ::::::::::::::::::::::::::: 170 3.14 Options for Linking ::::::::::::::::::::::::::::::::::::::::: 171 3.15 Options for Directory Search :::::::::::::::::::::::::::::::: 175 3.16 Options for Code Generation Conventions ::::::::::::::::::: 177 3.17 GCC Developer Options :::::::::::::::::::::::::::::::::::: 186 3.18 Machine-Dependent Options :::::::::::::::::::::::::::::::: 202 3.18.1 AArch64 Options :::::::::::::::::::::::::::::::::::::: 203 3.18.1.1 `-march' and `-mcpu' Feature Modifiers :::::::::::: 205 3.18.2 Adapteva Epiphany Options ::::::::::::::::::::::::::: 206 3.18.3 ARC Options :::::::::::::::::::::::::::::::::::::::::: 208 3.18.4 ARM Options:::::::::::::::::::::::::::::::::::::::::: 216 3.18.5 AVR Options :::::::::::::::::::::::::::::::::::::::::: 222 3.18.5.1 EIND and Devices with More Than 128 Ki Bytes of Flash::::::::::::::::::::::::::::::::::::::::::::::::::: 226 3.18.5.2 Handling of the RAMPD, RAMPX, RAMPY and RAMPZ Special Function Registers:::::::::::::::::::::::::::::::::::::: 228 3.18.5.3 AVR Built-in Macros:::::::::::::::::::::::::::::: 228 iv Using the GNU Compiler Collection (GCC) 3.18.6 Blackfin Options ::::::::::::::::::::::::::::::::::::::: 230 3.18.7 C6X Options::::::::::::::::::::::::::::::::::::::::::: 233 3.18.8 CRIS Options:::::::::::::::::::::::::::::::::::::::::: 234 3.18.9 CR16 Options ::::::::::::::::::::::::::::::::::::::::: 235 3.18.10 Darwin Options::::::::::::::::::::::::::::::::::::::: 236 3.18.11 DEC Alpha Options :::::::::::::::::::::::::::::::::: 239 3.18.12 FR30 Options :::::::::::::::::::::::::::::::::::::::: 244 3.18.13 FT32 Options :::::::::::::::::::::::::::::::::::::::: 244 3.18.14 FRV Options ::::::::::::::::::::::::::::::::::::::::: 244 3.18.15 GNU/Linux Options :::::::::::::::::::::::::::::::::: 248 3.18.16 H8/300 Options::::::::::::::::::::::::::::::::::::::: 249 3.18.17 HPPA Options:::::::::::::::::::::::::::::::::::::::: 249 3.18.18 IA-64 Options :::::::::::::::::::::::::::::::::::::::: 252 3.18.19 LM32 Options :::::::::::::::::::::::::::::::::::::::: 256 3.18.20 M32C Options :::::::::::::::::::::::::::::::::::::::: 256 3.18.21 M32R/D Options ::::::::::::::::::::::::::::::::::::: 257 3.18.22 M680x0 Options :::::::::::::::::::::::::::::::::::::: 258 3.18.23 MCore Options ::::::::::::::::::::::::::::::::::::::: 263 3.18.24 MeP Options ::::::::::::::::::::::::::::::::::::::::: 264 3.18.25 MicroBlaze Options ::::::::::::::::::::::::::::::::::: 266 3.18.26 MIPS Options :::::::::::::::::::::::::::::::::::::::: 267 3.18.27 MMIX Options ::::::::::::::::::::::::::::::::::::::: 281 3.18.28 MN10300 Options :::::::::::::::::::::::::::::::::::: 282 3.18.29 Moxie Options :::::::::::::::::::::::::::::::::::::::: 283 3.18.30 MSP430 Options:::::::::::::::::::::::::::::::::::::: 284 3.18.31 NDS32 Options ::::::::::::::::::::::::::::::::::::::: 285 3.18.32 Nios II Options ::::::::::::::::::::::::::::::::::::::: 286 3.18.33 Nvidia PTX Options :::::::::::::::::::::::::::::::::: 291 3.18.34 PDP-11 Options :::::::::::::::::::::::::::::::::::::: 291 3.18.35 picoChip Options ::::::::::::::::::::::::::::::::::::: 292 3.18.36 PowerPC Options::::::::::::::::::::::::::::::::::::: 293 3.18.37 RL78 Options::::::::::::::::::::::::::::::::::::::::: 293 3.18.38 IBM RS/6000 and PowerPC Options :::::::::::::::::: 294 3.18.39 RX Options :::::::::::::::::::::::::::::::::::::::::: 311 3.18.40 S/390 and zSeries Options :::::::::::::::::::::::::::: 314 3.18.41 Score Options::::::::::::::::::::::::::::::::::::::::: 317 3.18.42 SH Options ::::::::::::::::::::::::::::::::::::::::::: 318 3.18.43 Solaris 2 Options ::::::::::::::::::::::::::::::::::::: 324 3.18.44 SPARC Options :::::::::::::::::::::::::::::::::::::: 325 3.18.45 SPU Options ::::::::::::::::::::::::::::::::::::::::: 330 3.18.46 Options for System V ::::::::::::::::::::::::::::::::: 332 3.18.47 TILE-Gx Options ::::::::::::::::::::::::::::::::::::: 332 3.18.48 TILEPro Options ::::::::::::::::::::::::::::::::::::: 332 3.18.49 V850 Options ::::::::::::::::::::::::::::::::::::::::: 333 3.18.50 VAX Options ::::::::::::::::::::::::::::::::::::::::: 335 3.18.51 Visium Options ::::::::::::::::::::::::::::::::::::::: 335 3.18.52 VMS Options ::::::::::::::::::::::::::::::::::::::::: 336 3.18.53 VxWorks Options ::::::::::::::::::::::::::::::::::::: 337 v 3.18.54 x86 Options :::::::::::::::::::::::::::::::::::::::::: 337 3.18.55 x86 Windows Options::::::::::::::::::::::::::::::::: 357 3.18.56 Xstormy16 Options ::::::::::::::::::::::::::::::::::: 358 3.18.57 Xtensa Options ::::::::::::::::::::::::::::::::::::::: 358 3.18.58 zSeries Options ::::::::::::::::::::::::::::::::::::::: 360 3.19 Specifying Subprocesses and the Switches to Pass to Them :: 360 3.20 Environment Variables Affecting GCC :::::::::::::::::::::: 367 3.21 Using Precompiled Headers ::::::::::::::::::::::::::::::::: 370 4 C Implementation-Defined Behavior ::::::: 373 4.1 Translation :::::::::::::::::::::::::::::::::::::::::::::::::: 373 4.2 Environment::::::::::::::::::::::::::::::::::::::::::::::::: 373 4.3 Identifiers:::::::::::::::::::::::::::::::::::::::::::::::::::: 373 4.4 Characters ::::::::::::::::::::::::::::::::::::::::::::::::::: 374 4.5 Integers:::::::::::::::::::::::::::::::::::::::::::::::::::::: 375 4.6 Floating Point ::::::::::::::::::::::::::::::::::::::::::::::: 375 4.7 Arrays and Pointers:::::::::::::::::::::::::::::::::::::::::: 376 4.8 Hints :::::::::::::::::::::::::::::::::::::::::::::::::::::::: 377 4.9 Structures, Unions, Enumerations, and Bit-Fields::::::::::::: 377 4.10 Qualifiers :::::::::::::::::::::::::::::::::::::::::::::::::::