Using as

Table of Contents

• Using as
• 1 Overview
  • 1.1 Structure of this Manual
  • 1.2 The GNU Assembler
  • 1.3 Object File Formats
  • 1.4 Command Line
  • 1.5 Input Files
  • 1.6 Output (Object) File
  • 1.7 Error and Warning Messages
• 2 Command-Line Options
  • 2.1 Enable Listings: -a[cdghlns]
  • 2.2 --alternate
  • 2.3 -D
  • 2.4 Work Faster: -f
  • 2.5 .include Search Path: -I path
  • 2.6 Difference Tables: -K
  • 2.7 Include Local Symbols: -L
  • 2.8 Configuring listing output: --listing
  • 2.9 Assemble in MRI Compatibility Mode: -M
  • 2.10 Dependency Tracking: --MD
  • 2.11 Name the Object File: -o
  • 2.12 Join Data and Text Sections: -R
  • 2.13 Display Assembly Statistics: --statistics
  • 2.14 Compatible Output: --traditional-format
  • 2.15 Announce Version: -v
  • 2.16 Control Warnings: -W, --warn, --no-warn, --fatal-warnings
  • 2.17 Generate Object File in Spite of Errors: -Z
• 3 Syntax
  • 3.1 Preprocessing
  • 3.2 Whitespace
  • 3.3 Comments
  • 3.4 Symbols
  • 3.5 Statements
  • 3.6 Constants
    • 3.6.1 Character Constants
      • 3.6.1.1 Strings
      • 3.6.1.2 Characters
    • 3.6.2 Number Constants
      • 3.6.2.1 Integers
      • 3.6.2.2 Bignums
      • 3.6.2.3 Flonums
• 4 Sections and Relocation
  • 4.1 Background
  • 4.2 Linker Sections
  • 4.3 Assembler Internal Sections
  • 4.4 Sub-Sections
  • 4.5 bss Section
• 5 Symbols
  • 5.1 Labels
  • 5.2 Giving Symbols Other Values
  • 5.3 Symbol Names
  • 5.4 The Special Dot Symbol
  • 5.5 Symbol Attributes
    • 5.5.1 Value
    • 5.5.2 Type
    • 5.5.3 Symbol Attributes: a.out
      • 5.5.3.1 Descriptor
      • 5.5.3.2 Other
    • 5.5.4 Symbol Attributes for COFF
      • 5.5.4.1 Primary Attributes
      • 5.5.4.2 Auxiliary Attributes
    • 5.5.5 Symbol Attributes for SOM
• 6 Expressions
  • 6.1 Empty Expressions
  • 6.2 Integer Expressions
    • 6.2.1 Arguments
    • 6.2.2 Operators
    • 6.2.3 Prefix Operator
    • 6.2.4 Infix Operators
• 7 Assembler Directives
  • 7.1 .abort
  • 7.2 .ABORT (COFF)
  • 7.3 .align abs-expr, abs-expr, abs-expr
  • 7.4 .altmacro
  • 7.5 .ascii "string"...
  • 7.6 .asciz "string"...
  • 7.7 .balign[wl] abs-expr, abs-expr, abs-expr
  • 7.8 .byte expressions
  • 7.9 .cfi_sections section_list
  • 7.10 .cfi_startproc [simple]
  • 7.11 .cfi_endproc
  • 7.12 .cfi_personality encoding [, exp]
  • 7.13 .cfi_lsda encoding [, exp]
  • 7.14 .cfi_def_cfa register, offset
  • 7.15 .cfi_def_cfa_register register
  • 7.16 .cfi_def_cfa_offset offset
  • 7.17 .cfi_adjust_cfa_offset offset
  • 7.18 .cfi_offset register, offset
  • 7.19 .cfi_rel_offset register, offset
  • 7.20 .cfi_register register1, register2
  • 7.21 .cfi_restore register
  • 7.22 .cfi_undefined register
  • 7.23 .cfi_same_value register
  • 7.24 .cfi_remember_state,
  • 7.25 .cfi_return_column register
  • 7.26 .cfi_signal_frame
  • 7.27 .cfi_window_save
  • 7.28 .cfi_escape expression[, ...]
  • 7.29 .cfi_val_encoded_addr register, encoding, label
  • 7.30 .comm symbol , length
  • 7.31 .data subsection
  • 7.32 .def name
  • 7.33 .desc symbol, abs-expression
  • 7.34 .dim
  • 7.35 .double flonums
  • 7.36 .eject
  • 7.37 .else
  • 7.38 .elseif
  • 7.39 .end
  • 7.40 .endef
  • 7.41 .endfunc
  • 7.42 .endif
  • 7.43 .equ symbol, expression
  • 7.44 .equiv symbol, expression
  • 7.45 .eqv symbol, expression
  • 7.46 .err
  • 7.47 .error "string"
  • 7.48 .exitm
  • 7.49 .extern
  • 7.50 .fail expression
  • 7.51 .file
  • 7.52 .fill repeat , size , value
  • 7.53 .float flonums
  • 7.54 .func name[,label]
  • 7.55 .global symbol, .globl symbol
  • 7.56 .gnu_attribute tag,value
  • 7.57 .hidden names
  • 7.58 .hword expressions
  • 7.59 .ident
  • 7.60 .if absolute expression
  • 7.61 .incbin "file"[,skip[,count]]
  • 7.62 .include "file"
  • 7.63 .int expressions
  • 7.64 .internal names
  • 7.65 .irp symbol,values...
  • 7.66 .irpc symbol,values...
  • 7.67 .lcomm symbol , length
  • 7.68 .lflags
  • 7.69 .line line-number
  • 7.70 .linkonce [type]
  • 7.71 .list
  • 7.72 .ln line-number
  • 7.73 .loc fileno lineno [column] [options]
  • 7.74 .loc_mark_labels enable
  • 7.75 .local names
  • 7.76 .long expressions
  • 7.77 .macro
  • 7.78 .mri val
  • 7.79 .noaltmacro
  • 7.80 .nolist
  • 7.81 .octa bignums
  • 7.82 .org new-lc , fill
  • 7.83 .p2align[wl] abs-expr, abs-expr, abs-expr
  • 7.84 .popsection
  • 7.85 .previous
  • 7.86 .print string
  • 7.87 .protected names
  • 7.88 .psize lines , columns
  • 7.89 .purgem name
  • 7.90 .pushsection name [, subsection] [, "flags"[, @type[,arguments]]]
  • 7.91 .quad bignums
  • 7.92 .reloc offset, reloc_name[, expression]
  • 7.93 .rept count
  • 7.94 .sbttl "subheading"
  • 7.95 .scl class
  • 7.96 .section name
  • 7.97 .set symbol, expression
  • 7.98 .short expressions
  • 7.99 .single flonums
  • 7.100 .size
  • 7.101 .skip size , fill
  • 7.102 .sleb128 expressions
  • 7.103 .space size , fill
  • 7.104 .stabd, .stabn, .stabs
  • 7.105 .string "str", .string8 "str", .string16
  • 7.106 .struct expression
  • 7.107 .subsection name
  • 7.108 .symver
  • 7.109 .tag structname
  • 7.110 .text subsection
  • 7.111 .title "heading"
  • 7.112 .type
  • 7.113 .uleb128 expressions
  • 7.114 .val addr
  • 7.115 .version "string"
  • 7.116 .vtable_entry table, offset
  • 7.117 .vtable_inherit child, parent
  • 7.118 .warning "string"
  • 7.119 .weak names
  • 7.120 .weakref alias, target
  • 7.121 .word expressions
  • 7.122 Deprecated Directives
• 8 Object Attributes
  • 8.1 gnu Object Attributes
    • 8.1.1 Common gnu attributes
    • 8.1.2 MIPS Attributes
    • 8.1.3 PowerPC Attributes
  • 8.2 Defining New Object Attributes
• 9 Machine Dependent Features
  • 9.1 Alpha Dependent Features
    • 9.1.1 Notes
    • 9.1.2 Options
    • 9.1.3 Syntax
      • 9.1.3.1 Special Characters
      • 9.1.3.2 Register Names
      • 9.1.3.3 Relocations
    • 9.1.4 Floating Point
    • 9.1.5 Alpha Assembler Directives
    • 9.1.6 Opcodes
  • 9.2 ARC Dependent Features
    • 9.2.1 Options
    • 9.2.2 Syntax
      • 9.2.2.1 Special Characters
      • 9.2.2.2 Register Names
    • 9.2.3 Floating Point
    • 9.2.4 ARC Machine Directives
    • 9.2.5 Opcodes
  • 9.3 ARM Dependent Features
    • 9.3.1 Options
    • 9.3.2 Syntax
      • 9.3.2.1 Instruction Set Syntax
      • 9.3.2.2 Special Characters
      • 9.3.2.3 Register Names
      • 9.3.2.4 NEON Alignment Specifiers
    • 9.3.3 Floating Point
      • 9.3.3.1 ARM relocation generation
    • 9.3.4 ARM Machine Directives
    • 9.3.5 Opcodes
    • 9.3.6 Mapping Symbols
    • 9.3.7 Unwinding
  • 9.4 AVR Dependent Features
    • 9.4.1 Options
    • 9.4.2 Syntax
      • 9.4.2.1 Special Characters
      • 9.4.2.2 Register Names
      • 9.4.2.3 Relocatable Expression Modifiers
    • 9.4.3 Opcodes
  • 9.5 Blackfin Dependent Features
    • 9.5.1 Options
    • 9.5.2 Syntax
    • 9.5.3 Directives
  • 9.6 CR16 Dependent Features
    • 9.6.1 CR16 Operand Qualifiers
  • 9.7 CRIS Dependent Features
    • 9.7.1 Command-line Options
    • 9.7.2 Instruction expansion
    • 9.7.3 Symbols
    • 9.7.4 Syntax
      • 9.7.4.1 Special Characters
      • 9.7.4.2 Symbols in position-independent code
      • 9.7.4.3 Register names
      • 9.7.4.4 Assembler Directives
  • 9.8 D10V Dependent Features
    • 9.8.1 D10V Options
    • 9.8.2 Syntax
      • 9.8.2.1 Size Modifiers
      • 9.8.2.2 Sub-Instructions
      • 9.8.2.3 Special Characters
      • 9.8.2.4 Register Names
      • 9.8.2.5 Addressing Modes
      • 9.8.2.6 @WORD Modifier
    • 9.8.3 Floating Point
    • 9.8.4 Opcodes
  • 9.9 D30V Dependent Features
    • 9.9.1 D30V Options
    • 9.9.2 Syntax
      • 9.9.2.1 Size Modifiers
      • 9.9.2.2 Sub-Instructions
      • 9.9.2.3 Special Characters
      • 9.9.2.4 Guarded Execution
      • 9.9.2.5 Register Names
      • 9.9.2.6 Addressing Modes
    • 9.9.3 Floating Point
    • 9.9.4 Opcodes
  • 9.10 H8/300 Dependent Features
    • 9.10.1 Options
    • 9.10.2 Syntax
      • 9.10.2.1 Special Characters
      • 9.10.2.2 Register Names
      • 9.10.2.3 Addressing Modes
    • 9.10.3 Floating Point
    • 9.10.4 H8/300 Machine Directives
    • 9.10.5 Opcodes
  • 9.11 HPPA Dependent Features
    • 9.11.1 Notes
    • 9.11.2 Options
    • 9.11.3 Syntax
    • 9.11.4 Floating Point
    • 9.11.5 HPPA Assembler Directives
    • 9.11.6 Opcodes
  • 9.12 ESA/390 Dependent Features
    • 9.12.1 Notes
    • 9.12.2 Options
    • 9.12.3 Syntax
    • 9.12.4 Floating Point
    • 9.12.5 ESA/390 Assembler Directives
    • 9.12.6 Opcodes
  • 9.13 80386 Dependent Features
    • 9.13.1 Options
    • 9.13.2 x86 specific Directives
    • 9.13.3 AT&T Syntax versus Intel Syntax
    • 9.13.4 Instruction Naming
    • 9.13.5 AT&T Mnemonic versus Intel Mnemonic
    • 9.13.6 Register Naming
    • 9.13.7 Instruction Prefixes
    • 9.13.8 Memory References
    • 9.13.9 Handling of Jump Instructions
    • 9.13.10 Floating Point
    • 9.13.11 Intel's MMX and AMD's 3DNow! SIMD Operations
    • 9.13.12 AMD's Lightweight Profiling Instructions
    • 9.13.13 Writing 16-bit Code
    • 9.13.14 AT&T Syntax bugs
    • 9.13.15 Specifying CPU Architecture
    • 9.13.16 Notes
  • 9.14 Intel i860 Dependent Features
    • 9.14.1 i860 Notes
    • 9.14.2 i860 Command-line Options
      • 9.14.2.1 SVR4 compatibility options
      • 9.14.2.2 Other options
    • 9.14.3 i860 Machine Directives
    • 9.14.4 i860 Opcodes
      • 9.14.4.1 Other instruction support (pseudo-instructions)
  • 9.15 Intel 80960 Dependent Features
    • 9.15.1 i960 Command-line Options
    • 9.15.2 Floating Point
    • 9.15.3 i960 Machine Directives
    • 9.15.4 i960 Opcodes
      • 9.15.4.1 callj
      • 9.15.4.2 Compare-and-Branch
  • 9.16 IA-64 Dependent Features
    • 9.16.1 Options
    • 9.16.2 Syntax
      • 9.16.2.1 Special Characters
      • 9.16.2.2 Register Names
      • 9.16.2.3 IA-64 Processor-Status-Register (PSR) Bit Names
      • 9.16.2.4 Relocations
    • 9.16.3 Opcodes
  • 9.17 IP2K Dependent Features
    • 9.17.1 IP2K Options
  • 9.18 LM32 Dependent Features
    • 9.18.1 Options
    • 9.18.2 Syntax
      • 9.18.2.1 Register Names
      • 9.18.2.2 Relocatable Expression Modifiers
    • 9.18.3 Opcodes
  • 9.19 M32C Dependent Features
    • 9.19.1 M32C Options
    • 9.19.2 Symbolic Operand Modifiers
  • 9.20 M32R Dependent Features
    • 9.20.1 M32R Options
    • 9.20.2 M32R Directives
    • 9.20.3 M32R Warnings
  • 9.21 M680x0 Dependent Features
    • 9.21.1 M680x0 Options
    • 9.21.2 Syntax
    • 9.21.3 Motorola Syntax
    • 9.21.4 Floating Point
    • 9.21.5 680x0 Machine Directives
    • 9.21.6 Opcodes
      • 9.21.6.1 Branch Improvement
      • 9.21.6.2 Special Characters
  • 9.22 M68HC11 and M68HC12 Dependent Features
    • 9.22.1 M68HC11 and M68HC12 Options
    • 9.22.2 Syntax
    • 9.22.3 Symbolic Operand Modifiers
    • 9.22.4 Assembler Directives
    • 9.22.5 Floating Point
    • 9.22.6 Opcodes
      • 9.22.6.1 Branch Improvement
  • 9.23 MicroBlaze Dependent Features
    • 9.23.1 Directives
  • 9.24 MIPS Dependent Features
    • 9.24.1 Assembler options
    • 9.24.2 MIPS ECOFF object code
    • 9.24.3 Directives for debugging information
    • 9.24.4 Directives to override the size of symbols
    • 9.24.5 Directives to override the ISA level
    • 9.24.6 Directives for extending MIPS 16 bit instructions
    • 9.24.7 Directive to mark data as an instruction
    • 9.24.8 Directives to save and restore options
    • 9.24.9 Directives to control generation of MIPS ASE instructions
    • 9.24.10 Directives to override floating-point options
  • 9.25 MMIX Dependent Features
    • 9.25.1 Command-line Options
    • 9.25.2 Instruction expansion
    • 9.25.3 Syntax
      • 9.25.3.1 Special Characters
      • 9.25.3.2 Symbols
      • 9.25.3.3 Register names
      • 9.25.3.4 Assembler Directives
    • 9.25.4 Differences to mmixal
  • 9.26 MSP 430 Dependent Features
    • 9.26.1 Options
    • 9.26.2 Syntax
      • 9.26.2.1 Macros
      • 9.26.2.2 Special Characters
      • 9.26.2.3 Register Names
      • 9.26.2.4 Assembler Extensions
    • 9.26.3 Floating Point
    • 9.26.4 MSP 430 Machine Directives
    • 9.26.5 Opcodes
    • 9.26.6 Profiling Capability
  • 9.27 PDP-11 Dependent Features
    • 9.27.1 Options
      • 9.27.1.1 Code Generation Options
      • 9.27.1.2 Instruction Set Extension Options
      • 9.27.1.3 CPU Model Options
      • 9.27.1.4 Machine Model Options
    • 9.27.2 Assembler Directives
    • 9.27.3 PDP-11 Assembly Language Syntax
    • 9.27.4 Instruction Naming
    • 9.27.5 Synthetic Instructions
  • 9.28 picoJava Dependent Features
    • 9.28.1 Options
  • 9.29 PowerPC Dependent Features
    • 9.29.1 Options
    • 9.29.2 PowerPC Assembler Directives
  • 9.30 RX Dependent Features
    • 9.30.1 RX Options
    • 9.30.2 Symbolic Operand Modifiers
    • 9.30.3 Assembler Directives
    • 9.30.4 Floating Point
  • 9.31 IBM S/390 Dependent Features
    • 9.31.1 Options
    • 9.31.2 Special Characters
    • 9.31.3 Instruction syntax
      • 9.31.3.1 Register naming
      • 9.31.3.2 Instruction Mnemonics
      • 9.31.3.3 Instruction Operands
      • 9.31.3.4 Instruction Formats
      • 9.31.3.5 Instruction Aliases
      • 9.31.3.6 Instruction Operand Modifier
      • 9.31.3.7 Instruction Marker
      • 9.31.3.8 Literal Pool Entries
    • 9.31.4 Assembler Directives
    • 9.31.5 Floating Point
  • 9.32 SCORE Dependent Features
    • 9.32.1 Options
    • 9.32.2 SCORE Assembler Directives
  • 9.33 Renesas / SuperH SH Dependent Features
    • 9.33.1 Options
    • 9.33.2 Syntax
      • 9.33.2.1 Special Characters
      • 9.33.2.2 Register Names
      • 9.33.2.3 Addressing Modes
    • 9.33.3 Floating Point
    • 9.33.4 SH Machine Directives
    • 9.33.5 Opcodes
  • 9.34 SuperH SH64 Dependent Features
    • 9.34.1 Options
    • 9.34.2 Syntax
      • 9.34.2.1 Special Characters
      • 9.34.2.2 Register Names
      • 9.34.2.3 Addressing Modes
    • 9.34.3 SH64 Machine Directives
    • 9.34.4 Opcodes
  • 9.35 SPARC Dependent Features
    • 9.35.1 Options
    • 9.35.2 Enforcing aligned data
    • 9.35.3 Sparc Syntax
      • 9.35.3.1 Special Characters
      • 9.35.3.2 Register Names
      • 9.35.3.3 Constants
      • 9.35.3.4 Relocations
      • 9.35.3.5 Size Translations
    • 9.35.4 Floating Point
    • 9.35.5 Sparc Machine Directives
  • 9.36 TIC54X Dependent Features
    • 9.36.1 Options
    • 9.36.2 Blocking
    • 9.36.3 Environment Settings
    • 9.36.4 Constants Syntax
    • 9.36.5 String Substitution
    • 9.36.6 Local Labels
    • 9.36.7 Math Builtins
    • 9.36.8 Extended Addressing
    • 9.36.9 Directives
    • 9.36.10 Macros
    • 9.36.11 Memory-mapped Registers
  • 9.37 TIC6X Dependent Features
    • 9.37.1 TIC6X Options
    • 9.37.2 TIC6X Syntax
    • 9.37.3 TIC6X Directives
  • 9.38 Z80 Dependent Features
    • 9.38.1 Options
    • 9.38.2 Syntax
      • 9.38.2.1 Special Characters
      • 9.38.2.2 Register Names
      • 9.38.2.3 Case Sensitivity
    • 9.38.3 Floating Point
    • 9.38.4 Z80 Assembler Directives
    • 9.38.5 Opcodes
  • 9.39 Z8000 Dependent Features
    • 9.39.1 Options
    • 9.39.2 Syntax
      • 9.39.2.1 Special Characters
      • 9.39.2.2 Register Names
      • 9.39.2.3 Addressing Modes
    • 9.39.3 Assembler Directives for the Z8000
    • 9.39.4 Opcodes
  • 9.40 VAX Dependent Features
    • 9.40.1 VAX Command-Line Options
    • 9.40.2 VAX Floating Point
    • 9.40.3 Vax Machine Directives
    • 9.40.4 VAX Opcodes
    • 9.40.5 VAX Branch Improvement
    • 9.40.6 VAX Operands
    • 9.40.7 Not Supported on VAX
  • 9.41 v850 Dependent Features
    • 9.41.1 Options
    • 9.41.2 Syntax
      • 9.41.2.1 Special Characters
      • 9.41.2.2 Register Names
    • 9.41.3 Floating Point
    • 9.41.4 V850 Machine Directives
    • 9.41.5 Opcodes
  • 9.42 Xtensa Dependent Features
    • 9.42.1 Command Line Options
    • 9.42.2 Assembler Syntax
      • 9.42.2.1 Opcode Names
      • 9.42.2.2 Register Names
    • 9.42.3 Xtensa Optimizations
      • 9.42.3.1 Using Density Instructions
      • 9.42.3.2 Automatic Instruction Alignment
    • 9.42.4 Xtensa Relaxation
      • 9.42.4.1 Conditional Branch Relaxation
      • 9.42.4.2 Function Call Relaxation
      • 9.42.4.3 Other Immediate Field Relaxation
    • 9.42.5 Directives
      • 9.42.5.1 schedule
      • 9.42.5.2 longcalls
      • 9.42.5.3 transform
      • 9.42.5.4 literal
      • 9.42.5.5 literal_position
      • 9.42.5.6 literal_prefix
      • 9.42.5.7 absolute-literals
• 10 Reporting Bugs
  • 10.1 Have You Found a Bug?
  • 10.2 How to Report Bugs
• 11 Acknowledgements
• Appendix A GNU Free Documentation License
• AS Index