Using the GNU Compiler Collection

1 Using the GNU Compiler CollectionForgccversion (pre-release)(GCC)Richard M. Stallman and theGCCD eveloper CommunityPublished by:GNU PressWebsite: division of Software Franklin Street, Fifth FloorTel 617-542-5942 Boston, MA 02110-1301 USAFax 617-542-2652 Last printed October 2003 for GCC copies are available for $45 1988-2023 Free Software Foundation, is granted to copy, distribute and/or modify this document under the terms ofthe GNU Free Documentation License, Version or any later version published by theFree Software Foundation; with the Invariant Sections being Funding Free Software , theFront-Cover Texts being (a) (see below), and with the Back-Cover Texts being (b) (seebelow). A copy of the license is included in the section entitled GNU Free DocumentationLicense.

2 (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. Copiespublished by the Free Software Foundation raise funds for GNU Languages Supported by Standards Supported by Command Implementation-Defined ++ Implementation-Defined to the C Language to the C++ Objective-C a Test Coverage an Offline Gcda Profile Processing an Offline Gcda and Gcno Profile Dump Tool for dumping LTO object Known Causes of Trouble with Reporting How To Get Help with Contributing to GCC Free GNU Project and General Public Free Documentation to of Programming Languages Supported by Language Standards Supported by C Language.

3 C++ Language.. Objective-C and Objective-C++ Languages.. Go Language.. D language.. References for Other Languages..93 GCC Command Option Summary.. Options Controlling the Kind of Output.. Compiling C++ Programs.. Options Controlling C Dialect.. Options Controlling C++ Dialect.. Options Controlling Objective-C and Objective-C++ Dialects.. Options to Control Diagnostic Messages Formatting.. Options to Request or Suppress Warnings.. Options That Control Static Analysis.. Options for Debugging Your Program.. Options That Control Optimization.. Program Instrumentation Options.. Options Controlling the Preprocessor.. Passing Options to the Assembler.

4 Options for Linking.. Options for Directory Search.. Options for Code Generation Conventions.. GCC Developer Options.. Machine-Dependent Options.. AArch64 Options.. -march and -mcpu Feature Modifiers.. Adapteva Epiphany Options.. AMD GCN Options.. ARC Options.. ARM Options.. AVR Options.. Devices with More Than 128 Ki Bytes ofFlash..351ivUsing the GNU Compiler Collection (GCC) Handling of theRAMPD,RAMPX,RAMPYandRAMPZS pecialFunction Registers.. AVR Built-in Macros.. Blackfin Options.. C6X Options.. CRIS Options.. C-SKY Options.. Darwin Options.. DEC Alpha Options.. eBPF Options.. FR30 Options.. FT32 Options.. FRV Options.

5 GNU/Linux Options.. H8/300 Options.. HPPA Options.. IA-64 Options.. LM32 Options.. LoongArch Options.. M32C Options.. M32R/D Options.. M680x0 Options.. MCore Options.. MicroBlaze Options.. MIPS Options.. MMIX Options.. MN10300 Options.. Moxie Options.. MSP430 Options.. NDS32 Options.. Nios II Options.. Nvidia PTX Options.. OpenRISC Options.. PDP-11 Options.. PowerPC Options.. PRU Options.. RISC-V Options.. RL78 Options.. IBM RS/6000 and PowerPC Options.. RX Options.. S/390 and zSeries Options.. SH Options.. Solaris 2 Options.. SPARC Options.. Options for System V.. V850 Options.. VAX Options.

6 Visium Options.. VMS Options.. VxWorks Options.. x86 Options.. x86 Windows Options.. Xstormy16 Options.. Xtensa Options.. zSeries Options.. Specifying Subprocesses and the Switches to Pass to Them.. Environment Variables Affecting GCC.. Using Precompiled Headers.. C++ Modules.. Module Mapper.. Module Preprocessing.. Compiled Module Interface..5254 C Implementation-Defined Translation.. Environment.. Identifiers.. Characters.. Integers.. Floating Point.. Arrays and Pointers.. Hints.. Structures, Unions, Enumerations, and Bit-Fields.. Qualifiers.. Declarators.. Statements.. Preprocessing Directives.. Library Functions.

7 Architecture.. Locale-Specific Behavior..5355 C++ Implementation-Defined Conditionally-Supported Behavior.. Exception Handling..5376 Extensions to the C Language Statements and Declarations in Expressions.. Locally Declared Labels.. Labels as Values.. Nested Functions.. Nonlocal Gotos.. Constructing Function Calls.. Referring to a Type withtypeof.. Conditionals with Omitted Operands.. 128-bit Integers..549viUsing the GNU Compiler Collection (GCC) Double-Word Integers.. Complex Numbers.. Additional Floating Types.. Half-Precision Floating Point.. Decimal Floating Types.. Hex Floats.. Fixed-Point Types.. Named Address Spaces.

8 AVR Named Address Spaces.. M32C Named Address Spaces.. PRU Named Address Spaces.. RL78 Named Address Spaces.. x86 Named Address Spaces.. Arrays of Length Zero.. Structures with No Members.. Arrays of Variable Length.. Macros with a Variable Number of .. Slightly Looser Rules for Escaped Newlines.. Non-Lvalue Arrays May Have Subscripts.. Arithmetic onvoid- and Function-Pointers.. Pointer Arguments in Variadic Functions.. Pointers to Arrays with Qualifiers Work as Expected.. Non-Constant Initializers.. Compound Literals.. Designated Initializers.. Case Ranges.. Cast to a Union Type.. Mixed Declarations, Labels and Code.. Declaring Attributes of Functions.

9 Common Function Attributes.. AArch64 Function Attributes.. Inlining rules.. AMD GCN Function Attributes.. ARC Function Attributes.. ARM Function Attributes.. AVR Function Attributes.. Blackfin Function Attributes.. BPF Function Attributes.. C-SKY Function Attributes.. Epiphany Function Attributes.. H8/300 Function Attributes.. IA-64 Function Attributes.. M32C Function Attributes.. M32R/D Function Attributes.. m68k Function Attributes.. MCORE Function Attributes.. MicroBlaze Function Attributes.. Microsoft Windows Function Attributes.. MIPS Function Attributes.. MSP430 Function Attributes.. NDS32 Function Attributes.. Nios II Function Attributes.

10 Nvidia PTX Function Attributes.. PowerPC Function Attributes.. RISC-V Function Attributes.. RL78 Function Attributes.. RX Function Attributes.. S/390 Function Attributes.. SH Function Attributes.. Symbian OS Function Attributes.. V850 Function Attributes.. Visium Function Attributes.. x86 Function Attributes.. Xstormy16 Function Attributes.. Specifying Attributes of Variables.. Common Variable Attributes.. ARC Variable Attributes.. AVR Variable Attributes.. Blackfin Variable Attributes.. H8/300 Variable Attributes.. IA-64 Variable Attributes.. LoongArch Variable Attributes.. M32R/D Variable Attributes.. Microsoft Windows Variable Attributes.