Using the GNU Compiler Collection (GCC)

Contents:

• Copyright
• Introduction
• Programming Languages Supported by GCC
• Language Standards Supported by GCC
  • C Language
  • C++ Language
  • Objective-C and Objective-C++ Languages
  • Go Language
  • D language
  • References for Other Languages
• GCC Command Options
  • Description
  • 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
  • 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
      • EIND and Devices with More Than 128 Ki Bytes of Flash
      • Handling of the RAMPD, RAMPX, RAMPY and RAMPZ Special Function 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
    • GNU/Linux Options
    • H8/300 Options
    • HPPA Options
    • IA-64 Options
    • LM32 Options
    • LoongArch Options
    • M32C Options
    • M32R/D Options
    • M680x0 Options
    • MCore Options
    • MeP 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
    • picoChip Options
    • PowerPC Options
    • PRU Options
    • RISC-V Options
    • RL78 Options
    • IBM RS/6000 and PowerPC Options
    • RX Options
    • S/390 and zSeries Options
    • Score Options
    • SH Options
    • Solaris 2 Options
    • SPARC Options
    • Options for System V
    • V850 Options
    • VAX Options
    • 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
    • Environment
  • Using Precompiled Headers
  • C++ Modules
    • Module Mapper
    • Module Preprocessing
    • Compiled Module Interface
• C Implementation-Defined Behavior
  • Translation
  • Environment
  • Identifiers
  • Characters
  • Integers
  • Floating Point
  • Arrays and Pointers
  • Hints
  • Structures, Unions, Enumerations, and Bit-Fields
  • Qualifiers
  • Declarators
  • Statements
  • Preprocessing Directives
  • Library Functions
  • Architecture
  • Locale-Specific Behavior
• C++ Implementation-Defined Behavior
  • Conditionally-Supported Behavior
  • Exception Handling
• Extensions to the C Language Family
  • Statements and Declarations in Expressions
  • Locally Declared Labels
  • Labels as Values
  • Nested Functions
  • Nonlocal Gotos
  • Constructing Function Calls
  • Referring to a Type with typeof
  • Conditionals with Omitted Operands
  • 128-bit Integers
  • Double-Word Integers
  • Complex Numbers
  • Additional Floating Types
  • Half-Precision Floating Point
  • Decimal Floating Types
  • Hex Floats
  • Fixed-Point Types
  • Named Address Spaces
    • 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 Arguments.
  • Slightly Looser Rules for Escaped Newlines
  • Non-Lvalue Arrays May Have Subscripts
  • Arithmetic on void- 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
    • 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
    • MeP Function Attributes
    • MicroBlaze Function Attributes
    • Microsoft Windows Function Attributes
    • MIPS Function Attributes
    • MSP430 Function Attributes
    • NDS32 Function Attributes
    • Nios II Function Attributes
    • 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
    • MeP Variable Attributes
    • Microsoft Windows Variable Attributes
    • MSP430 Variable Attributes
    • Nvidia PTX Variable Attributes
    • PowerPC Variable Attributes
    • RL78 Variable Attributes
    • V850 Variable Attributes
    • x86 Variable Attributes
    • Xstormy16 Variable Attributes
  • Specifying Attributes of Types
    • Common Type Attributes
    • ARC Type Attributes
    • ARM Type Attributes
    • BPF Type Attributes
    • MeP Type Attributes
    • PowerPC Type Attributes
    • x86 Type Attributes
  • Label Attributes
  • Enumerator Attributes
  • Statement Attributes
  • Attribute Syntax
    • Label Attributes
    • Enumerator Attributes
    • Statement Attributes
    • Type Attributes
    • All other attributes
  • Prototypes and Old-Style Function Definitions
  • C++ Style Comments
  • Dollar Signs in Identifier Names
  • The Character ESC in Constants
  • Determining the Alignment of Functions, Types or Variables
  • An Inline Function is As Fast As a Macro
  • When is a Volatile Object Accessed?
  • How to Use Inline Assembly Language in C Code
    • Basic Asm — Assembler Instructions Without Operands
    • Qualifiers
    • Parameters
    • Remarks
    • Extended Asm - Assembler Instructions with C Expression Operands
    • Qualifiers
    • Parameters
    • Remarks
      • Volatile
      • Assembler Template
    • Special format strings
    • Multiple assembler dialects in asm templates
      • Output Operands
      • Flag Output Operands
      • Input Operands
      • Clobbers and Scratch Registers
      • Goto Labels
      • x86 Operand Modifiers
      • x86 Floating-Point asm Operands
      • MSP430 Operand Modifiers
    • Constraints for asm Operands
    • Simple Constraints
    • Multiple Alternative Constraints
    • Register Class Preferences
    • Constraint Modifier Characters
    • Constraints for Particular Machines
      • AArch64 family—config/aarch64/constraints.md
      • AMD GCN —config/gcn/constraints.md
      • ARC —config/arc/constraints.md
      • ARM family—config/arm/constraints.md
      • AVR family—config/avr/constraints.md
      • Blackfin family—config/bfin/constraints.md
      • Epiphany—config/epiphany/constraints.md
      • FRV—config/frv/frv.h
      • FT32—config/ft32/constraints.md
      • Hewlett-Packard PA-RISC—config/pa/pa.h
      • Intel IA-64—config/ia64/ia64.h
      • M32C—config/m32c/m32c.cc
      • LoongArch—config/loongarch/constraints.md
      • MicroBlaze—config/microblaze/constraints.md
      • MIPS—config/mips/constraints.md
      • Motorola 680x0—config/m68k/constraints.md
      • Moxie—config/moxie/constraints.md
      • MSP430—config/msp430/constraints.md
      • NDS32—config/nds32/constraints.md
      • Nios II family—config/nios2/constraints.md
      • OpenRISC—config/or1k/constraints.md
      • PDP-11—config/pdp11/constraints.md
      • PowerPC and IBM RS6000—config/rs6000/constraints.md
      • PRU—config/pru/constraints.md
      • RL78—config/rl78/constraints.md
      • RISC-V—config/riscv/constraints.md
      • RX—config/rx/constraints.md
      • S/390 and zSeries—config/s390/s390.h
      • SPARC—config/sparc/sparc.h
      • TI C6X family—config/c6x/constraints.md
      • Visium—config/visium/constraints.md
      • x86 family—config/i386/constraints.md
      • Xstormy16—config/stormy16/stormy16.h
      • Xtensa—config/xtensa/constraints.md
    • Controlling Names Used in Assembler Code
    • Assembler names for data
    • Assembler names for functions
    • Variables in Specified Registers
      • Defining Global Register Variables
    • Declaring the variable
    • Using the variable
      • Specifying Registers for Local Variables
    • Size of an asm
  • Alternate Keywords
  • Incomplete enum Types
  • Function Names as Strings
  • Getting the Return or Frame Address of a Function
  • Using Vector Instructions through Built-in Functions
  • Support for offsetof
  • Legacy __sync Built-in Functions for Atomic Memory Access
  • Built-in Functions for Memory Model Aware Atomic Operations
  • Built-in Functions to Perform Arithmetic with Overflow Checking
  • x86-Specific Memory Model Extensions for Transactional Memory
  • Object Size Checking Built-in Functions
  • Other Built-in Functions Provided by GCC
  • Built-in Functions Specific to Particular Target Machines
    • AArch64 Built-in Functions
    • Alpha Built-in Functions
    • Altera Nios II Built-in Functions
    • ARC Built-in Functions
    • ARC SIMD Built-in Functions
    • ARM iWMMXt Built-in Functions
    • ARM C Language Extensions (ACLE)
    • ARM Floating Point Status and Control Intrinsics
    • ARM ARMv8-M Security Extensions
    • AVR Built-in Functions
    • Blackfin Built-in Functions
    • BPF Built-in Functions
    • FR-V Built-in Functions
      • Argument Types
      • Directly-Mapped Integer Functions
      • Directly-Mapped Media Functions
      • Raw Read/Write Functions
      • Other Built-in Functions
    • MIPS DSP Built-in Functions
    • MIPS Paired-Single Support
    • MIPS Loongson Built-in Functions
      • Paired-Single Arithmetic
      • Paired-Single Built-in Functions
      • MIPS-3D Built-in Functions
    • MIPS SIMD Architecture (MSA) Support
      • MIPS SIMD Architecture Built-in Functions
    • Other MIPS Built-in Functions
    • MSP430 Built-in Functions
    • NDS32 Built-in Functions
    • picoChip Built-in Functions
    • Basic PowerPC Built-in Functions
      • Basic PowerPC Built-in Functions Available on all Configurations
      • Basic PowerPC Built-in Functions Available on ISA 2.05
      • Basic PowerPC Built-in Functions Available on ISA 2.06
      • Basic PowerPC Built-in Functions Available on ISA 2.07
      • Basic PowerPC Built-in Functions Available on ISA 3.0
      • Basic PowerPC Built-in Functions Available on ISA 3.1
    • PowerPC AltiVec/VSX Built-in Functions
      • PowerPC AltiVec Built-in Functions on ISA 2.05
      • PowerPC AltiVec Built-in Functions Available on ISA 2.06
      • PowerPC AltiVec Built-in Functions Available on ISA 2.07
      • PowerPC AltiVec Built-in Functions Available on ISA 3.0
      • PowerPC AltiVec Built-in Functions Available on ISA 3.1
    • PowerPC Hardware Transactional Memory Built-in Functions
      • PowerPC HTM Low Level Built-in Functions
      • PowerPC HTM High Level Inline Functions
    • PowerPC Atomic Memory Operation Functions
    • PowerPC Matrix-Multiply Assist Built-in Functions
    • PRU Built-in Functions
    • RISC-V Built-in Functions
    • RX Built-in Functions
    • S/390 System z Built-in Functions
    • SH Built-in Functions
    • SPARC VIS Built-in Functions
    • TI C6X Built-in Functions
    • x86 Built-in Functions
    • x86 Transactional Memory Intrinsics
    • x86 Control-Flow Protection Intrinsics
  • Format Checks Specific to Particular Target Machines
    • Solaris Format Checks
    • Darwin Format Checks
  • Pragmas Accepted by GCC
    • AArch64 Pragmas
    • ARM Pragmas
    • M32C Pragmas
    • MeP Pragmas
    • PRU Pragmas
    • RS/6000 and PowerPC Pragmas
    • S/390 Pragmas
    • Darwin Pragmas
    • Solaris Pragmas
    • Symbol-Renaming Pragmas
    • Structure-Layout Pragmas
    • Weak Pragmas
    • Diagnostic Pragmas
    • Visibility Pragmas
    • Push/Pop Macro Pragmas
    • Function Specific Option Pragmas
    • Loop-Specific Pragmas
  • Unnamed Structure and Union Fields
  • Thread-Local Storage
    • ISO/IEC 9899:1999 Edits for Thread-Local Storage
    • ISO/IEC 14882:1998 Edits for Thread-Local Storage
  • Binary Constants using the 0b Prefix
• Extensions to the C++ Language
  • Vague Linkage
  • Function Multiversioning
  • Type Traits
  • C++ Concepts
  • Deprecated Features
  • Backwards Compatibility
  • When is a Volatile C++ Object Accessed?
  • Restricting Pointer Aliasing
  • C++ Interface and Implementation Pragmas
  • Where’s the Template?
  • Extracting the Function Pointer from a Bound Pointer to Member Function
  • C++-Specific Variable, Function, and Type Attributes
• GNU Objective-C Features
  • GNU Objective-C Runtime API
    • Modern GNU Objective-C Runtime API
    • Traditional GNU Objective-C Runtime API
  • +load: Executing Code before main
    • What You Can and Cannot Do in +load
  • Type Encoding
    • Legacy Type Encoding
    • @encode
    • Method Signatures
  • Garbage Collection
  • Constant String Objects
  • compatibility_alias
  • Exceptions
  • Synchronization
  • Fast Enumeration
    • Using Fast Enumeration
    • C99-Like Fast Enumeration Syntax
    • Fast Enumeration Details
    • Fast Enumeration Protocol
  • Messaging with the GNU Objective-C Runtime
    • Dynamically Registering Methods
    • Forwarding Hook
• Binary Compatibility
• gcov—a Test Coverage Program
  • Introduction to gcov
  • Invoking gcov
    • Options
  • Using gcov with GCC Optimization
  • Brief Description of gcov Data Files
  • Data File Relocation to Support Cross-Profiling
  • Profiling and Test Coverage in Freestanding Environments
    • Overview
    • Tutorial
    • System Initialization Caveats
• gcov-tool—an Offline Gcda Profile Processing Tool
  • Description
  • Options
• gcov-dump—an Offline Gcda and Gcno Profile Dump Tool
  • Description
  • Options
• lto-dump—Tool for dumping LTO object files.
  • Description
  • Options
• Known Causes of Trouble with GCC
  • Actual Bugs We Haven’t Fixed Yet
  • Interoperation
  • Incompatibilities of GCC
  • Fixed Header Files
  • Standard Libraries
  • Disappointments and Misunderstandings
  • Common Misunderstandings with GNU C++
    • Declare and Define Static Members
    • Name Lookup, Templates, and Accessing Members of Base Classes
    • Temporaries May Vanish Before You Expect
    • Implicit Copy-Assignment for Virtual Bases
  • Certain Changes We Don’t Want to Make
  • Warning Messages and Error Messages
• Reporting Bugs
  • Have You Found a Bug?
  • How and Where to Report Bugs
• How To Get Help with GCC
• Contributing to GCC Development
• Funding Free Software
• The GNU Project and GNU/Linux
• GNU GENERAL PUBLIC LICENSE
  • Preamble
  • TERMS AND CONDITIONS
    • 0. Definitions.
    • 1. Source Code.
    • 2. Basic Permissions.
    • 3. Protecting Users’ Legal Rights From Anti-Circumvention Law.
    • 4. Conveying Verbatim Copies.
    • 5. Conveying Modified Source Versions.
    • 6. Conveying Non-Source Forms.
    • 7. Additional Terms.
    • 8. Termination.
    • 9. Acceptance Not Required for Having Copies.
    • 10. Automatic Licensing of Downstream Recipients.
    • 11. Patents.
    • 12. No Surrender of Others’ Freedom.
    • 13. Use with the GNU Affero General Public License.
    • 14. Revised Versions of this License.
    • 15. Disclaimer of Warranty.
    • 16. Limitation of Liability.
    • 17. Interpretation of Sections 15 and 16.
  • How to Apply These Terms to Your New Programs
• GNU Free Documentation License
  • Preamble
  • 1. APPLICABILITY AND DEFINITIONS
  • 2. VERBATIM COPYING
  • 3. COPYING IN QUANTITY
  • 4. MODIFICATIONS
  • 5. COMBINING DOCUMENTS
  • 6. COLLECTIONS OF DOCUMENTS
  • 7. AGGREGATION WITH INDEPENDENT WORKS
  • 8. TRANSLATION
  • 9. TERMINATION
  • 10. FUTURE REVISIONS OF THIS LICENSE
  • 11. RELICENSING
  • ADDENDUM: How to use this License for your documents
• Contributors to GCC
• Indexes and tables
  • TODO