This file is a user guide to the GNU assembler as (GNU Binutils) version 2.35.
This document is distributed under the terms of the GNU Free Documentation License. A copy of the license is included in the section entitled “GNU Free Documentation License”.
Overview
Here is a brief summary of how to invoke as. For details, see Command-Line Options.
as [ -a [ cdghlns ][=file]] [ - alternate] [ -D ]
[ - compress-debug-sections] [ - nocompress-debug-sections]
[ - debug-prefix-map old=new]
[ - defsym sym=val] [ -f ] [ -g ] [ - gstabs]
[ - gstabs+] [ - gdwarf-] [ - gdwarf-sections]
[ - gdwarf-cie-version=VERSION]
[ - help] [ -I dir] [ -J ]
[ -K ] [ -L ] [ - listing-lhs-width=NUM]
[ - listing-lhs-width2=NUM] [ - listing-rhs-width=NUM]
[ - listing-cont-lines=NUM] [ - keep-locals]
[ - no-pad-sections]
[ -o objfile] [ -R ]
[ - hash-size=NUM] [ - reduce-memory-overheads]
[ - statistics]
[ -v ] [ -version ] [ - version]
[ -W ] [ - warn] [ - fatal-warnings] [ -w ] [ -x ]
[ -Z ] [ @ FILE]
[ - sectname-subst] [ - size-check=[error|warning]]
[ - elf-stt-common=[no|yes]]
[ - generate-missing-build-notes=[no|yes]]
[ - target-help] [target-options]
[ - |files …]
Target Loongarch options:
[ -mabi =ABI]
@file
Read command-line options from file. The options read are inserted in place of
the original @file option. If file does not exist, or cannot be read, then the
option will be treated literally, and not removed.
Options in file are separated by whitespace. A whitespace character may be
included in an option by surrounding the entire option in either single or
double quotes. Any character (including a backslash) may be included by
prefixing the character to be included with a backslash. The file may itself
contain additional @file options; any such options will be processed
recursively.
-a[cdghlmns]
Turn on listings, in any of a variety of ways:
-ac
omit false conditionals
-ad
omit debugging directives
-ag
include general information, like as version and options passed
-ah
include high-level source
-al
include assembly
-am
include macro expansions
-an
omit forms processing
-as
include symbols
=file
set the name of the listing file
You may combine these options; for example, use '-aln' for assembly listing
without forms processing. The '=file' option, if used, must be the last one.
By itself, '-a' defaults to '-ahls'.
--alternate
Begin in alternate macro mode. See [`.altmacro`](Altmacro.html#Altmacro).
--compress-debug-sections
Compress DWARF debug sections using zlib with SHF_COMPRESSED from the ELF ABI.
The resulting object file may not be compatible with older linkers and object
file utilities. Note if compression would make a given section _larger_ then
it is not compressed.
--compress-debug-sections=none
--compress-debug-sections=zlib
--compress-debug-sections=zlib-gnu
--compress-debug-sections=zlib-gabi
These options control how DWARF debug sections are compressed. \--compress-
debug-sections=none is equivalent to \--nocompress-debug-sections.
\--compress-debug-sections=zlib and \--compress-debug-sections=zlib-gabi are
equivalent to \--compress-debug-sections. \--compress-debug-sections=zlib-gnu
compresses DWARF debug sections using zlib. The debug sections are renamed to
begin with '.zdebug'. Note if compression would make a given section _larger_
then it is not compressed nor renamed.
--nocompress-debug-sections
Do not compress DWARF debug sections. This is usually the default for all
targets except the x86/x86_64, but a configure time option can be used to
override this.
-D
Ignored. This option is accepted for script compatibility with calls to other
assemblers.
--debug-prefix-map old=new
When assembling files in directory old, record debugging information
describing them as in new instead.
--defsym sym=value
Define the symbol sym to be value before assembling the input file. value must
be an integer constant. As in C, a leading '0x' indicates a hexadecimal value,
and a leading '0' indicates an octal value. The value of the symbol can be
overridden inside a source file via the use of a `.set` pseudo-op.
-f
"fast"--skip whitespace and comment preprocessing (assume source is compiler output).
-g
--gen-debug
Generate debugging information for each assembler source line using whichever
debug format is preferred by the target. This currently means either STABS,
ECOFF or DWARF2.
--gstabs
Generate stabs debugging information for each assembler line. This may help
debugging assembler code, if the debugger can handle it.
--gstabs+
Generate stabs debugging information for each assembler line, with GNU
extensions that probably only gdb can handle, and that could make other
debuggers crash or refuse to read your program. This may help debugging
assembler code. Currently the only GNU extension is the location of the
current working directory at assembling time.
--gdwarf-2
Generate DWARF2 debugging information for each assembler line. This may help
debugging assembler code, if the debugger can handle it. Note--this option is
only supported by some targets, not all of them.
--gdwarf-3
This option is the same as the \--gdwarf-2 option, except that it allows for
the possibility of the generation of extra debug information as per version 3
of the DWARF specification. Note - enabling this option does not guarantee the
generation of any extra infortmation, the choice to do so is on a per target
basis.
--gdwarf-4
This option is the same as the \--gdwarf-2 option, except that it allows for
the possibility of the generation of extra debug information as per version 4
of the DWARF specification. Note - enabling this option does not guarantee the
generation of any extra infortmation, the choice to do so is on a per target
basis.
--gdwarf-5
This option is the same as the \--gdwarf-2 option, except that it allows for
the possibility of the generation of extra debug information as per version 5
of the DWARF specification. Note - enabling this option does not guarantee the
generation of any extra infortmation, the choice to do so is on a per target
basis.
--gdwarf-sections
Instead of creating a .debug_line section, create a series of .debug_line.foo
sections where foo is the name of the corresponding code section. For example
a code section called .text.func will have its dwarf line number information
placed into a section called .debug_line.text.func. If the code section is
just called .text then debug line section will still be called just
.debug_line without any suffix.
--gdwarf-cie-version=version
Control which version of DWARF Common Information Entries (CIEs) are produced.
When this flag is not specificed the default is version 1, though some targets
can modify this default. Other possible values for version are 3 or 4.
--size-check=error
--size-check=warning
Issue an error or warning for invalid ELF .size directive.
--elf-stt-common=no
--elf-stt-common=yes
These options control whether the ELF assembler should generate common symbols
with the `STT_COMMON` type. The default can be controlled by a configure
option \--enable-elf-stt-common.
--generate-missing-build-notes=yes
--generate-missing-build-notes=no
These options control whether the ELF assembler should generate GNU Build
attribute notes if none are present in the input sources. The default can be
controlled by the \--enable-generate-build-notes configure option.
--help
Print a summary of the command-line options and exit.
--target-help
Print a summary of all target specific options and exit.
-I dir
Add directory dir to the search list for `.include` directives.
-J
Don't warn about signed overflow.
-K
Issue warnings when difference tables altered for long displacements.
-L
--keep-locals
Keep (in the symbol table) local symbols. These symbols start with system-
specific local label prefixes, typically '.L' for ELF systems or 'L' for
traditional a.out systems. See [Symbol Names](Symbol-Names.html#Symbol-Names).
--listing-lhs-width=number
Set the maximum width, in words, of the output data column for an assembler
listing to number.
--listing-lhs-width2=number
Set the maximum width, in words, of the output data column for continuation
lines in an assembler listing to number.
--listing-rhs-width=number
Set the maximum width of an input source line, as displayed in a listing, to
number bytes.
--listing-cont-lines=number
Set the maximum number of lines printed in a listing for a single line of
input to number \+ 1.
--no-pad-sections
Stop the assembler for padding the ends of output sections to the alignment of
that section. The default is to pad the sections, but this can waste space
which might be needed on targets which have tight memory constraints.
-o objfile
Name the object-file output from `as` objfile.
-R
Fold the data section into the text section.
--hash-size=number
Set the default size of GAS's hash tables to a prime number close to number.
Increasing this value can reduce the length of time it takes the assembler to
perform its tasks, at the expense of increasing the assembler's memory
requirements. Similarly reducing this value can reduce the memory requirements
at the expense of speed.
--reduce-memory-overheads
This option reduces GAS's memory requirements, at the expense of making the
assembly processes slower. Currently this switch is a synonym for '\--hash-
size=4051', but in the future it may have other effects as well.
--sectname-subst
Honor substitution sequences in section names. See [`.section
name`](Section.html#Section-Name-Substitutions).
--statistics
Print the maximum space (in bytes) and total time (in seconds) used by
assembly.
--strip-local-absolute
Remove local absolute symbols from the outgoing symbol table.
-v
-version
Print the `as` version.
--version
Print the `as` version and exit.
-W
--no-warn
Suppress warning messages.
--fatal-warnings
Treat warnings as errors.
--warn
Don't suppress warning messages or treat them as errors.
-w
Ignored.
-x
Ignored.
-Z
Generate an object file even after errors.
-- | files …
Standard input, or source files to assemble.
