Using the GNU Compiler Collection For gcc version 7.5.0 (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 1988-2017 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 :::::::::::::::::::: 395 5 C++ Implementation-Defined Behavior ::::::::::::::::: 403 6 Extensions to the C Language Family ::::::::::::::::::: 405 7 Extensions to the C++ Language :::::::::::::::::::::: 737 8 GNU Objective-C Features ::::::::::::::::::::::::::: 751 9 Binary Compatibility :::::::::::::::::::::::::::::::: 767 10 gcov|a Test Coverage Program ::::::::::::::::::::::: 771 11 gcov-tool|an Offline Gcda Profile Processing Tool ::::::: 781 12 gcov-dump|an Offline Gcda and Gcno Profile Dump Tool :: 785 13 Known Causes of Trouble with GCC :::::::::::::::::::: 787 14 Reporting Bugs ::::::::::::::::::::::::::::::::::::: 803 15 How To Get Help with GCC :::::::::::::::::::::::::: 805 16 Contributing to GCC Development ::::::::::::::::::::: 807 Funding Free Software ::::::::::::::::::::::::::::::::::: 809 The GNU Project and GNU/Linux::::::::::::::::::::::::: 811 GNU General Public License :::::::::::::::::::::::::::::: 813 GNU Free Documentation License ::::::::::::::::::::::::: 825 Contributors to GCC :::::::::::::::::::::::::::::::::::: 833 Option Index :::::::::::::::::::::::::::::::::::::::::: 851 Keyword Index ::::::::::::::::::::::::::::::::::::::::: 875 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 HSA Intermediate Language (HSAIL) :::::::::::::::::::::::::: 8 2.6 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 :::::::::::::::::::::::::::::::::::: 33 3.4 Options Controlling C Dialect ::::::::::::::::::::::::::::::::: 33 3.5 Options Controlling C++ Dialect ::::::::::::::::::::::::::::: 40 3.6 Options Controlling Objective-C and Objective-C++ Dialects :: 53 3.7 Options to Control Diagnostic Messages Formatting ::::::::::: 56 3.8 Options to Request or Suppress Warnings ::::::::::::::::::::: 59 3.9 Options for Debugging Your Program :::::::::::::::::::::::: 101 3.10 Options That Control Optimization ::::::::::::::::::::::::: 106 3.11 Program Instrumentation Options::::::::::::::::::::::::::: 164 3.12 Options Controlling the Preprocessor:::::::::::::::::::::::: 176 3.13 Passing Options to the Assembler ::::::::::::::::::::::::::: 183 3.14 Options for Linking ::::::::::::::::::::::::::::::::::::::::: 183 3.15 Options for Directory Search :::::::::::::::::::::::::::::::: 188 3.16 Options for Code Generation Conventions ::::::::::::::::::: 191 3.17 GCC Developer Options :::::::::::::::::::::::::::::::::::: 201 3.18 Machine-Dependent Options :::::::::::::::::::::::::::::::: 217 3.18.1 AArch64 Options :::::::::::::::::::::::::::::::::::::: 217 3.18.1.1 `-march' and `-mcpu' Feature Modifiers :::::::::::: 220 3.18.2 Adapteva Epiphany Options ::::::::::::::::::::::::::: 221 3.18.3 ARC Options :::::::::::::::::::::::::::::::::::::::::: 223 3.18.4 ARM Options:::::::::::::::::::::::::::::::::::::::::: 232 3.18.5 AVR Options :::::::::::::::::::::::::::::::::::::::::: 238 3.18.5.1 EIND and Devices with More Than 128 Ki Bytes of Flash::::::::::::::::::::::::::::::::::::::::::::::::::: 243 3.18.5.2 Handling of the RAMPD, RAMPX, RAMPY and RAMPZ Special Function Registers:::::::::::::::::::::::::::::::::::::: 244 iv Using the GNU Compiler Collection (GCC) 3.18.5.3 AVR Built-in Macros:::::::::::::::::::::::::::::: 245 3.18.6 Blackfin Options ::::::::::::::::::::::::::::::::::::::: 247 3.18.7 C6X Options::::::::::::::::::::::::::::::::::::::::::: 250 3.18.8 CRIS Options:::::::::::::::::::::::::::::::::::::::::: 250 3.18.9 CR16 Options ::::::::::::::::::::::::::::::::::::::::: 252 3.18.10 Darwin Options::::::::::::::::::::::::::::::::::::::: 252 3.18.11 DEC Alpha Options :::::::::::::::::::::::::::::::::: 256 3.18.12 FR30 Options :::::::::::::::::::::::::::::::::::::::: 260 3.18.13 FT32 Options :::::::::::::::::::::::::::::::::::::::: 261 3.18.14 FRV Options ::::::::::::::::::::::::::::::::::::::::: 261 3.18.15 GNU/Linux Options :::::::::::::::::::::::::::::::::: 265 3.18.16 H8/300 Options::::::::::::::::::::::::::::::::::::::: 265 3.18.17 HPPA Options:::::::::::::::::::::::::::::::::::::::: 266 3.18.18 IA-64 Options :::::::::::::::::::::::::::::::::::::::: 269 3.18.19 LM32 Options :::::::::::::::::::::::::::::::::::::::: 272 3.18.20 M32C Options :::::::::::::::::::::::::::::::::::::::: 273 3.18.21 M32R/D Options ::::::::::::::::::::::::::::::::::::: 273 3.18.22 M680x0 Options :::::::::::::::::::::::::::::::::::::: 275 3.18.23 MCore Options ::::::::::::::::::::::::::::::::::::::: 280 3.18.24 MeP Options ::::::::::::::::::::::::::::::::::::::::: 281 3.18.25 MicroBlaze Options ::::::::::::::::::::::::::::::::::: 282 3.18.26 MIPS Options :::::::::::::::::::::::::::::::::::::::: 284 3.18.27 MMIX Options ::::::::::::::::::::::::::::::::::::::: 298 3.18.28 MN10300 Options :::::::::::::::::::::::::::::::::::: 299 3.18.29 Moxie Options :::::::::::::::::::::::::::::::::::::::: 300 3.18.30 MSP430 Options:::::::::::::::::::::::::::::::::::::: 300 3.18.31 NDS32 Options ::::::::::::::::::::::::::::::::::::::: 302 3.18.32 Nios II Options ::::::::::::::::::::::::::::::::::::::: 303 3.18.33 Nvidia PTX Options :::::::::::::::::::::::::::::::::: 307 3.18.34 PDP-11 Options :::::::::::::::::::::::::::::::::::::: 308 3.18.35 picoChip Options ::::::::::::::::::::::::::::::::::::: 309 3.18.36 PowerPC Options::::::::::::::::::::::::::::::::::::: 310 3.18.37 RISC-V Options :::::::::::::::::::::::::::::::::::::: 310 3.18.38 RL78 Options::::::::::::::::::::::::::::::::::::::::: 312 3.18.39 IBM RS/6000 and PowerPC Options :::::::::::::::::: 313 3.18.40 RX Options :::::::::::::::::::::::::::::::::::::::::: 330 3.18.41 S/390 and zSeries Options :::::::::::::::::::::::::::: 333 3.18.42 Score Options::::::::::::::::::::::::::::::::::::::::: 337 3.18.43 SH Options ::::::::::::::::::::::::::::::::::::::::::: 337 3.18.44 Solaris 2 Options ::::::::::::::::::::::::::::::::::::: 343 3.18.45 SPARC Options :::::::::::::::::::::::::::::::::::::: 344 3.18.46 SPU Options ::::::::::::::::::::::::::::::::::::::::: 350 3.18.47 Options for System V ::::::::::::::::::::::::::::::::: 352 3.18.48 TILE-Gx Options ::::::::::::::::::::::::::::::::::::: 352 3.18.49 TILEPro Options ::::::::::::::::::::::::::::::::::::: 353 3.18.50 V850 Options ::::::::::::::::::::::::::::::::::::::::: 353 3.18.51 VAX Options ::::::::::::::::::::::::::::::::::::::::: 355 3.18.52 Visium Options ::::::::::::::::::::::::::::::::::::::: 356 v 3.18.53 VMS Options ::::::::::::::::::::::::::::::::::::::::: 357 3.18.54 VxWorks Options ::::::::::::::::::::::::::::::::::::: 357 3.18.55 x86 Options :::::::::::::::::::::::::::::::::::::::::: 357 3.18.56 x86 Windows Options::::::::::::::::::::::::::::::::: 379 3.18.57 Xstormy16 Options ::::::::::::::::::::::::::::::::::: 380 3.18.58 Xtensa Options ::::::::::::::::::::::::::::::::::::::: 380 3.18.59 zSeries Options ::::::::::::::::::::::::::::::::::::::: 382 3.19 Specifying Subprocesses and the Switches to Pass to Them :: 382 3.20 Environment Variables Affecting GCC :::::::::::::::::::::: 389 3.21 Using Precompiled Headers ::::::::::::::::::::::::::::::::: 392 4 C Implementation-Defined Behavior ::::::: 395 4.1 Translation :::::::::::::::::::::::::::::::::::::::::::::::::: 395 4.2 Environment::::::::::::::::::::::::::::::::::::::::::::::::: 395 4.3 Identifiers:::::::::::::::::::::::::::::::::::::::::::::::::::: 395 4.4 Characters ::::::::::::::::::::::::::::::::::::::::::::::::::: 396 4.5 Integers:::::::::::::::::::::::::::::::::::::::::::::::::::::: 397 4.6 Floating Point ::::::::::::::::::::::::::::::::::::::::::::::: 397 4.7 Arrays and Pointers::::::::::::::::::::::::::::::::::::::::::