as: AArch64 Options
9.1.1 Options
-------------
'-EB'
This option specifies that the output generated by the assembler
should be marked as being encoded for a big-endian processor.
'-EL'
This option specifies that the output generated by the assembler
should be marked as being encoded for a little-endian processor.
'-mabi=ABI'
Specify which ABI the source code uses. The recognized arguments
are: 'ilp32' and 'lp64', which decides the generated object file in
ELF32 and ELF64 format respectively. The default is 'lp64'.
'-mcpu=PROCESSOR[+EXTENSION...]'
This option specifies the target processor. The assembler will
issue an error message if an attempt is made to assemble an
instruction which will not execute on the target processor. The
following processor names are recognized: 'cortex-a35',
'cortex-a53', 'cortex-a55', 'cortex-a57', 'cortex-a72',
'cortex-a73', 'cortex-a75', 'cortex-a76', 'ares', 'exynos-m1',
'falkor', 'qdf24xx', 'saphira', 'thunderx', 'vulcan', 'xgene1' and
'xgene2'. The special name 'all' may be used to allow the
assembler to accept instructions valid for any supported processor,
including all optional extensions.
In addition to the basic instruction set, the assembler can be told
to accept, or restrict, various extension mnemonics that extend the
processor. 
AArch64 Extensions.
If some implementations of a particular processor can have an
extension, then then those extensions are automatically enabled.
Consequently, you will not normally have to specify any additional
extensions.
'-march=ARCHITECTURE[+EXTENSION...]'
This option specifies the target architecture. The assembler will
issue an error message if an attempt is made to assemble an
instruction which will not execute on the target architecture. The
following architecture names are recognized: 'armv8-a',
'armv8.1-a', 'armv8.2-a', 'armv8.3-a', 'armv8.4-a' and 'armv8.5-a'.
If both '-mcpu' and '-march' are specified, the assembler will use
the setting for '-mcpu'. If neither are specified, the assembler
will default to '-mcpu=all'.
The architecture option can be extended with the same instruction
set extension options as the '-mcpu' option. Unlike '-mcpu',
extensions are not always enabled by default, AArch64
Extensions.
'-mverbose-error'
This option enables verbose error messages for AArch64 gas. This
option is enabled by default.
'-mno-verbose-error'
This option disables verbose error messages in AArch64 gas.
Info Catalog
as: AArch64-Dependent
as: AArch64 Extensions