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701 lines
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701 lines
25 KiB
Plaintext
@c Copyright (C) 2009-2025 Free Software Foundation, Inc.
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@c Contributed by ARM Ltd.
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@c This is part of the GAS manual.
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@c For copying conditions, see the file as.texinfo.
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@c man end
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@ifset GENERIC
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@page
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@node AArch64-Dependent
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@chapter AArch64 Dependent Features
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@end ifset
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@ifclear GENERIC
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@node Machine Dependencies
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@chapter AArch64 Dependent Features
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@end ifclear
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@cindex AArch64 support
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@menu
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* AArch64 Options:: Options
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* AArch64 Extensions:: Extensions
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* AArch64 Syntax:: Syntax
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* AArch64 Floating Point:: Floating Point
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* AArch64 Directives:: AArch64 Machine Directives
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* AArch64 Opcodes:: Opcodes
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* AArch64 Mapping Symbols:: Mapping Symbols
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@end menu
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@node AArch64 Options
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@section Options
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@cindex AArch64 options (none)
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@cindex options for AArch64 (none)
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@c man begin OPTIONS
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@table @gcctabopt
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@cindex @option{-EB} command-line option, AArch64
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@item -EB
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This option specifies that the output generated by the assembler should
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be marked as being encoded for a big-endian processor.
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@cindex @option{-EL} command-line option, AArch64
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@item -EL
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This option specifies that the output generated by the assembler should
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be marked as being encoded for a little-endian processor.
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@cindex @option{-mabi=} command-line option, AArch64
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@item -mabi=@var{abi}
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Specify which ABI the source code uses. The recognized arguments
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are: @code{ilp32} and @code{lp64}, which decides the generated object
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file in ELF32 and ELF64 format respectively. The default is @code{lp64}.
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@cindex @option{-mcpu=} command-line option, AArch64
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@item -mcpu=@var{processor}[+@var{extension}@dots{}]
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This option specifies the target processor. The assembler will issue an error
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message if an attempt is made to assemble an instruction which will not execute
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on the target processor. The following processor names are recognized:
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@code{cortex-a34},
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@code{cortex-a35},
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@code{cortex-a53},
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@code{cortex-a55},
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@code{cortex-a57},
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@code{cortex-a65},
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@code{cortex-a65ae},
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@code{cortex-a72},
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@code{cortex-a73},
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@code{cortex-a75},
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@code{cortex-a76},
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@code{cortex-a76ae},
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@code{cortex-a77},
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@code{cortex-a78},
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@code{cortex-a78ae},
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@code{cortex-a78c},
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@code{cortex-a510},
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@code{cortex-a520},
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@code{cortex-a710},
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@code{cortex-a720},
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@code{ares},
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@code{exynos-m1},
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@code{falkor},
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@code{neoverse-n1},
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@code{neoverse-n2},
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@code{neoverse-e1},
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@code{neoverse-v1},
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@code{qdf24xx},
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@code{saphira},
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@code{thunderx},
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@code{vulcan},
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@code{xgene1}
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@code{xgene2},
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@code{cortex-r82},
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@code{cortex-x1},
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@code{cortex-x2},
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@code{cortex-x3},
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and
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@code{cortex-x4}.
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The special name @code{all} may be used to allow the assembler to accept
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instructions valid for any supported processor, including all optional
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extensions.
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In addition to the basic instruction set, the assembler can be told to
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accept, or restrict, various extension mnemonics that extend the
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processor. @xref{AArch64 Extensions}.
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If some implementations of a particular processor can have an
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extension, then then those extensions are automatically enabled.
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Consequently, you will not normally have to specify any additional
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extensions.
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@cindex @option{-march=} command-line option, AArch64
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@item -march=@var{architecture}[+@var{extension}@dots{}]
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This option specifies the target architecture. The assembler will
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issue an error message if an attempt is made to assemble an
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instruction which will not execute on the target architecture. The
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following architecture names are recognized: @code{armv8-a},
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@code{armv8.1-a}, @code{armv8.2-a}, @code{armv8.3-a}, @code{armv8.4-a}
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@code{armv8.5-a}, @code{armv8.6-a}, @code{armv8.7-a}, @code{armv8.8-a},
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@code{armv8.9-a}, @code{armv8-r}, @code{armv9-a}, @code{armv9.1-a},
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@code{armv9.2-a}, @code{armv9.3-a}, @code{armv9.4-a} and @code{armv9.5-a}.
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If both @option{-mcpu} and @option{-march} are specified, the
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assembler will use the setting for @option{-mcpu}. If neither are
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specified, the assembler will default to @option{-mcpu=all}.
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The architecture option can be extended with the same instruction set
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extension options as the @option{-mcpu} option. Unlike
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@option{-mcpu}, extensions are not always enabled by default.
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@xref{AArch64 Extensions}.
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@cindex @code{-mverbose-error} command-line option, AArch64
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@item -mverbose-error
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This option enables verbose error messages for AArch64 gas. This option
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is enabled by default.
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@cindex @code{-mno-verbose-error} command-line option, AArch64
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@item -mno-verbose-error
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This option disables verbose error messages in AArch64 gas.
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@cindex @code{-menable-sysreg-checking} command-line option, AArch64
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@item -menable-sysreg-checking
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This option enables error messages that are issued if an attempt is made to
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assemble a system register access which will not execute on the target
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architecture.
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@end table
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@c man end
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@node AArch64 Extensions
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@section Architecture Extensions
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The tables below lists the permitted architecture extensions and architecture
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versions that are supported by the assembler, including a brief description and
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a list of other extensions that they depend upon.
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Multiple extensions may be specified, separated by a @code{+}.
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Extension mnemonics may also be removed from those the assembler
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accepts. This is done by prepending @code{no} to the option that adds
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the extension. Extensions that are removed must be listed after all
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extensions that have been added.
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Enabling an extension that depends upon other extensions (either directly or
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recursively) will automatically cause those extensions to be enabled.
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Similarly, disabling an extension that is required by other extensions will
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automatically cause those extensions to be disabled.
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@multitable @columnfractions .16 .22 .62
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@headitem Extension @tab Depends upon @tab Description
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@item @code{aes} @tab @code{simd}
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@tab Enable the AES and PMULL cryptographic extensions.
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@item @code{bf16} @tab @code{fp}
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@tab Enable BFloat16 extension.
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@item @code{brbe} @tab
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@tab Enable the Branch Record Buffer extension.
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@item @code{chk} @tab
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@tab Enable the Check Feature Status Extension.
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@item @code{cmpbr} @tab
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@tab Enable Compare and Branch instructions.
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@item @code{compnum} @tab @code{simd}
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@tab Enable the complex number SIMD extensions. An alias of @code{fcma}.
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@item @code{cpa} @tab
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@tab Enable the Checked Pointer Arithmetic extension.
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@item @code{crc} @tab
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@tab Enable CRC instructions.
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@item @code{crypto} @tab @code{simd}
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@tab Enable cryptographic extensions. This is equivalent to @code{aes+sha2}.
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@item @code{cssc} @tab
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@tab Enable the Armv8.9-A Common Short Sequence Compression instructions.
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@item @code{d128} @tab @code{lse128}
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@tab Enable the 128-bit Page Descriptor Extension. This implies @code{lse128}.
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@item @code{dotprod} @tab @code{simd}
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@tab Enable the Dot Product extension.
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@item @code{f32mm} @tab @code{sve}
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@tab Enable the F32 Matrix Multiply extension
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@item @code{f64mm} @tab @code{sve}
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@tab Enable the F64 Matrix Multiply extension.
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@item @code{f8f16mm} @tab @code{simd} @code{fp8}
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@tab Enable 8-bit floating-point matrix multiply-accumulate to half-precision instructions.
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@item @code{f8f32mm} @tab @code{simd} @code{fp}
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@tab Enable 8-bit floating-point matrix multiply-accumulate to single-precision instructions.
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@item @code{faminmax} @tab @code{simd}
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@tab Enable the famin and famax instructions.
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@item @code{fcma} @tab @code{fp16}, @code{simd}
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@tab Enable the complex number SIMD extensions.
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@item @code{flagm} @tab
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@tab Enable Flag Manipulation instructions.
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@item @code{flagm2} @tab @code{flagm}
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@tab Enable FlagM2 flag conversion instructions.
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@item @code{fp} @tab
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@tab Enable floating-point extensions.
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@item @code{fp8} @tab
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@tab Enable the Floating Point 8 (FP8) extension.
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@item @code{fp8dot2} @tab @code{fp8}
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@tab Enable the FP8 2-way dot product instructions.
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@item @code{fp8dot4} @tab @code{fp8}
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@tab Enable the FP8 4-way dot product instructions.
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@item @code{fp8fma} @tab @code{fp8}
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@tab Enable the FP8 FMA instructions.
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@item @code{fp16fml} @tab @code{fp16}
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@tab Enable Armv8.2 16-bit floating-point multiplication variant support.
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@item @code{fp16} @tab @code{fp}
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@tab Enable Armv8.2 16-bit floating-point support.
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@item @code{fprcvt} @tab @code{fp}
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@tab Enable Armv9.6 fprcvt instructions.
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@item @code{frintts} @tab @code{fp}
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@tab Enable floating-point round to integral value instructions.
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@item @code{gcie} @tab
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@tab Enable the GICv5 (Generic Interrupt Controller) CPU Interface Extension.
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@item @code{gcs} @tab
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@tab Enable the Guarded Control Stack Extension.
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@item @code{hbc} @tab
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@tab Enable Armv8.8-A hinted conditional branch instructions
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@item @code{i8mm} @tab @code{simd}
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@tab Enable the Int8 Matrix Multiply extension.
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@item @code{ite} @tab
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@tab Enable the TRCIT instruction.
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@item @code{jscvt} @tab @code{fp}
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@tab Enable the @code{fjcvtzs} JavaScript conversion instruction.
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@item @code{lor} @tab
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@tab Enable Limited Ordering Regions extensions.
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@item @code{ls64} @tab
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@tab Enable the 64 Byte Loads/Stores extensions.
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@item @code{lse} @tab
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@tab Enable Large System extensions.
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@item @code{lse128} @tab @code{lse}
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@tab Enable the 128-bit Atomic Instructions extension.
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@item @code{lsfe} @tab @code{fp}
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@tab Enable Large System Float Extension.
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@item @code{lsui} @tab
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@tab Enable Unprivileged Load/Store instructions.
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@item @code{lut} @tab @code{simd}
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@tab Enable the Lookup Table (LUT) extension.
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@item @code{memtag} @tab
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@tab Enable Armv8.5-A Memory Tagging Extensions.
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@item @code{mops} @tab
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@tab Enable Armv8.8-A memcpy and memset acceleration instructions
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@item @code{occmo} @tab
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@tab Enable Outer Cacheable Cache Maintenance Operations.
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@item @code{pan} @tab
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@tab Enable Privileged Access Never support.
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@item @code{pauth} @tab
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@tab Enable Pointer Authentication.
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@item @code{pops} @tab
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@tab Enable Point of Physical Storage.
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@item @code{predres} @tab
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@tab Enable execution and data prediction restriction instructions.
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@item @code{predres2} @tab @code{predres}
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@tab Enable additional prediction restriction instructions.
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@item @code{profile} @tab
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@tab Enable statistical profiling extensions.
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@item @code{ras} @tab
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@tab Enable the Reliability, Availability and Serviceability extension.
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@item @code{rasv2} @tab @code{ras}
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@tab Enable the Reliability, Availability and Serviceability extension v2.
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@item @code{rcpc} @tab
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@tab Enable the Load-Acquire RCpc instructions extension.
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@item @code{rcpc2} @tab @code{rcpc}
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@tab Enable the Load-Acquire RCpc instructions extension v2.
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@item @code{rcpc3} @tab @code{rcpc2}
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@tab Enable the Load-Acquire RCpc instructions extension v3.
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@item @code{rdma} @tab @code{simd}
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@tab Enable rounding doubling multiply accumulate instructions.
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@item @code{rdm} @tab @code{simd}
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@tab An alias of @code{rdma}.
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@item @code{rng} @tab
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@tab Enable Armv8.5-A random number instructions.
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@item @code{sb} @tab
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@tab Enable the speculation barrier instruction sb.
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@item @code{sha2} @tab @code{simd}
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@tab Enable the SHA1 and SHA256 cryptographic extensions.
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@item @code{sha3} @tab @code{sha2}
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@tab Enable the SHA512 and SHA3 cryptographic extensions.
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@item @code{simd} @tab @code{fp}
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@tab Enable Advanced SIMD extensions.
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@item @code{sm4} @tab @code{simd}
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@tab Enable the SM3 and SM4 cryptographic extensions.
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@item @code{sme} @tab @code{bf16}, @code{fp16}, @code{fcma}
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@tab Enable the Scalable Matrix Extension. This will also enable @code{sve2}, but disabling @code{sve2} does not disable @code{sme}.
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@item @code{sme-b16b16} @tab @code{sme2}, @code{sve-b16b16}
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@tab Enable SME ZA-targeting non-widening BFloat16 instructions.
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@item @code{sme-f8f16} @tab @code{sme2}, @code{fp8}
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@tab Enable the SME F8F16 Extension.
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@item @code{sme-f8f32} @tab @code{sme2}, @code{fp8}
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@tab Enable the SME F8F32 Extension.
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@item @code{sme-f16f16} @tab @code{sme2}
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@tab Enable the SME2 F16F16 Extension.
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@item @code{sme-f64f64} @tab @code{sme}
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@tab Enable SME F64F64 Extension.
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@item @code{sme-i16i64} @tab @code{sme}
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@tab Enable SME I16I64 Extension.
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@item @code{sme-lutv2} @tab
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@tab Enable SME Lookup Table v2 (LUTv2) extension.
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@item @code{sme-tmop} @tab @code{sme2}
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@tab Enable SME structured sparsity outer product instructions.
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@item @code{sme2} @tab @code{sme}
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@tab Enable SME2.
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@item @code{sme2p1} @tab @code{sme2}
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@tab Enable SME2.1.
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@item @code{sme2p2} @tab @code{sme2p1}
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@tab Enable SME2.2.
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@item @code{ssbs} @tab
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@tab Enable Speculative Store Bypassing Safe state read and write.
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@item @code{ssve-aes} @tab @code{sme2}, @code{sve-aes}
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@tab Enable SVE AES instructions in streaming mode.
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@item @code{ssve-fp8dot2} @tab @code{sme2}, @code{fp8}
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@tab Enable the Streaming SVE FP8 2-way dot product instructions.
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@item @code{ssve-fp8dot4} @tab @code{sme2}, @code{fp8}
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@tab Enable the Streaming SVE FP8 4-way dot product instructions.
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@item @code{ssve-fp8fma} @tab @code{sme2}, @code{fp8}
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@tab Enable the Streaming SVE FP8 FMA instructions.
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@item @code{sve} @tab @code{fcma}
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@tab Enable the Scalable Vector Extension.
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@item @code{sve-aes} @tab @code{aes}
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@tab Enable the SVE2 AES and PMULL Extensions.
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@item @code{sve-aes2} @tab
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@tab Enable the SVE-AES2 extension.
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@item @code{sve-b16b16} @tab
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@tab Enable the SVE B16B16 extension. These instructions also require either @code{+sve2} or @code{+sme2}.
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@item @code{sve-bfscale} @tab
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@tab Enable the SVE BFSCALE extension. These instructions also require either @code{+sve2} or @code{+sme2}.
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@item @code{sve-f16f32mm} @tab @code{sve}
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@tab Enable the SVE_F16F32MM extension.
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@item @code{sve2} @tab @code{sve}
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@tab Enable SVE2.
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@item @code{sve2-aes} @tab @code{sve2}, @code{sve-aes}
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@tab Enable the SVE2 AES and PMULL Extensions.
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@item @code{sve2-bitperm} @tab @code{sve2}
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@tab Enable the SVE2 BITPERM Extension.
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@item @code{sve2-sha3} @tab @code{sve2}, @code{sha3}
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@tab Enable the SVE2 SHA3 Extension.
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@item @code{sve2-sm4} @tab @code{sve2}, @code{sm4}
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@tab Enable the SVE2 SM4 Extension.
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@item @code{sve2p1} @tab @code{sve2}
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@tab Enable SVE2.1.
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@item @code{sve2p2} @tab @code{sve2p1}
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@tab Enable SVE2.2.
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@item @code{the} @tab
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@tab Enable the Translation Hardening Extension.
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@item @code{tme} @tab
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@tab Enable the Transactional Memory Extension.
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@item @code{wfxt} @tab
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@tab Enable @code{wfet} and @code{wfit} instructions.
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@item @code{xs} @tab
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@tab Enable the XS memory attribute extension.
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@end multitable
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@multitable @columnfractions .20 .80
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@headitem Architecture Version @tab Includes
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@item @code{armv8-a} @tab @code{simd}, @code{chk}, @code{ras}
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@item @code{armv8.1-a} @tab @code{armv8-a}, @code{crc}, @code{lse}, @code{rdma}, @code{pan}, @code{lor}
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@item @code{armv8.2-a} @tab @code{armv8.1-a}
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@item @code{armv8.3-a} @tab @code{armv8.2-a}, @code{fcma}, @code{jscvt}, @code{pauth}, @code{rcpc}
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@item @code{armv8.4-a} @tab @code{armv8.3-a}, @code{fp16fml}, @code{dotprod}, @code{flagm}, @code{rcpc2}
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@item @code{armv8.5-a} @tab @code{armv8.4-a}, @code{frintts}, @code{flagm2}, @code{predres}, @code{sb}, @code{ssbs}
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@item @code{armv8.6-a} @tab @code{armv8.5-a}, @code{bf16}, @code{i8mm}
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@item @code{armv8.7-a} @tab @code{armv8.6-a}, @code{ls64}, @code{xs}, @code{wfxt}
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@item @code{armv8.8-a} @tab @code{armv8.7-a}, @code{hbc}, @code{mops}
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@item @code{armv8.9-a} @tab @code{armv8.8-a}, @code{rasv2}, @code{predres2}
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@item @code{armv9-a} @tab @code{armv8.5-a}, @code{sve2}
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@item @code{armv9.1-a} @tab @code{armv9-a}, @code{armv8.6-a}
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@item @code{armv9.2-a} @tab @code{armv9.1-a}, @code{armv8.7-a}
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@item @code{armv9.3-a} @tab @code{armv9.2-a}, @code{armv8.8-a}
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@item @code{armv9.4-a} @tab @code{armv9.3-a}, @code{armv8.9-a}
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@item @code{armv9.5-a} @tab @code{armv9.4-a}, @code{cpa}, @code{lut}, @code{faminmax}
|
|
@item @code{armv9.6-a} @tab @code{armv9.5-a}, @code{cmpbr}, @code{fprcvt}, @code{lsui}, @code{occmo}, @code{sve2p2}
|
|
@item @code{armv8-r} @tab @code{armv8.4-a+nolor}
|
|
@end multitable
|
|
|
|
@node AArch64 Syntax
|
|
@section Syntax
|
|
@menu
|
|
* AArch64-Chars:: Special Characters
|
|
* AArch64-Regs:: Register Names
|
|
* AArch64-Relocations:: Relocations
|
|
@end menu
|
|
|
|
@node AArch64-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex line comment character, AArch64
|
|
@cindex AArch64 line comment character
|
|
The presence of a @samp{//} on a line indicates the start of a comment
|
|
that extends to the end of the current line. If a @samp{#} appears as
|
|
the first character of a line, the whole line is treated as a comment.
|
|
|
|
@cindex line separator, AArch64
|
|
@cindex statement separator, AArch64
|
|
@cindex AArch64 line separator
|
|
The @samp{;} character can be used instead of a newline to separate
|
|
statements.
|
|
|
|
@cindex immediate character, AArch64
|
|
@cindex AArch64 immediate character
|
|
The @samp{#} can be optionally used to indicate immediate operands.
|
|
|
|
@node AArch64-Regs
|
|
@subsection Register Names
|
|
|
|
@cindex AArch64 register names
|
|
@cindex register names, AArch64
|
|
Please refer to the section @samp{Register names} of @samp{Arm
|
|
Architecture Reference Manual for A-profile architecture}, which
|
|
is available at @uref{https://developer.arm.com/}.
|
|
|
|
@node AArch64-Relocations
|
|
@subsection Relocations
|
|
|
|
@cindex relocations, AArch64
|
|
@cindex AArch64 relocations
|
|
@cindex MOVN, MOVZ and MOVK group relocations, AArch64
|
|
Relocations for @samp{MOVZ} and @samp{MOVK} instructions can be generated
|
|
by prefixing the label with @samp{#:abs_g2:} etc.
|
|
For example to load the 48-bit absolute address of @var{foo} into x0:
|
|
|
|
@smallexample
|
|
movz x0, #:abs_g2:foo // bits 32-47, overflow check
|
|
movk x0, #:abs_g1_nc:foo // bits 16-31, no overflow check
|
|
movk x0, #:abs_g0_nc:foo // bits 0-15, no overflow check
|
|
@end smallexample
|
|
|
|
@cindex ADRP, ADD, LDR/STR group relocations, AArch64
|
|
Relocations for @samp{ADRP}, and @samp{ADD}, @samp{LDR} or @samp{STR}
|
|
instructions can be generated by prefixing the label with
|
|
@samp{:pg_hi21:} and @samp{#:lo12:} respectively.
|
|
|
|
For example to use 33-bit (+/-4GB) pc-relative addressing to
|
|
load the address of @var{foo} into x0:
|
|
|
|
@smallexample
|
|
adrp x0, :pg_hi21:foo
|
|
add x0, x0, #:lo12:foo
|
|
@end smallexample
|
|
|
|
Or to load the value of @var{foo} into x0:
|
|
|
|
@smallexample
|
|
adrp x0, :pg_hi21:foo
|
|
ldr x0, [x0, #:lo12:foo]
|
|
@end smallexample
|
|
|
|
Note that @samp{:pg_hi21:} is optional.
|
|
|
|
@smallexample
|
|
adrp x0, foo
|
|
@end smallexample
|
|
|
|
is equivalent to
|
|
|
|
@smallexample
|
|
adrp x0, :pg_hi21:foo
|
|
@end smallexample
|
|
|
|
@node AArch64 Floating Point
|
|
@section Floating Point
|
|
|
|
@cindex floating point, AArch64 (@sc{ieee})
|
|
@cindex AArch64 floating point (@sc{ieee})
|
|
The AArch64 architecture uses @sc{ieee} floating-point numbers.
|
|
|
|
@node AArch64 Directives
|
|
@section AArch64 Machine Directives
|
|
|
|
@cindex machine directives, AArch64
|
|
@cindex AArch64 machine directives
|
|
@table @code
|
|
|
|
@c AAAAAAAAAAAAAAAAAAAAAAAAA
|
|
|
|
@cindex @code{.arch} directive, AArch64
|
|
@item .arch @var{name}
|
|
Select the target architecture. Valid values for @var{name} are the same as
|
|
for the @option{-march} command-line option.
|
|
|
|
Specifying @code{.arch} clears any previously selected architecture
|
|
extensions.
|
|
|
|
@cindex @code{.arch_extension} directive, AArch64
|
|
@item .arch_extension @var{name}
|
|
Add or remove an architecture extension to the target architecture. Valid
|
|
values for @var{name} are the same as those accepted as architectural
|
|
extensions by the @option{-mcpu} command-line option.
|
|
|
|
@code{.arch_extension} may be used multiple times to add or remove extensions
|
|
incrementally to the architecture being compiled for.
|
|
|
|
@c BBBBBBBBBBBBBBBBBBBBBBBBBB
|
|
@c CCCCCCCCCCCCCCCCCCCCCCCCCC
|
|
|
|
@cindex @code{.cfi_mte_tagged_frame} directive, AArch64
|
|
@item @code{.cfi_mte_tagged_frame}
|
|
The @code{.cfi_mte_tagged_frame} directive inserts a 'G' character into the
|
|
CIE corresponding to the current frame's FDE, meaning that the associated
|
|
frames may modify MTE tags on the stack space they use. This information is
|
|
intended to be used by the stack unwinder in order to properly untag stack
|
|
frames.
|
|
|
|
@cindex @code{.cpu} directive, AArch64
|
|
@item .cpu @var{name}
|
|
Set the target processor. Valid values for @var{name} are the same as
|
|
those accepted by the @option{-mcpu=} command-line option.
|
|
|
|
@c DDDDDDDDDDDDDDDDDDDDDDDDDD
|
|
|
|
@cindex @code{.dword} directive, AArch64
|
|
@item .dword @var{expressions}
|
|
The @code{.dword} directive produces 64 bit values.
|
|
|
|
@c EEEEEEEEEEEEEEEEEEEEEEEEEE
|
|
|
|
@cindex @code{.even} directive, AArch64
|
|
@item .even
|
|
The @code{.even} directive aligns the output on the next even byte
|
|
boundary.
|
|
|
|
@c FFFFFFFFFFFFFFFFFFFFFFFFFF
|
|
|
|
@cindex @code{.float16} directive, AArch64
|
|
@item .float16 @var{value [,...,value_n]}
|
|
Place the half precision floating point representation of one or more
|
|
floating-point values into the current section.
|
|
The format used to encode the floating point values is always the
|
|
IEEE 754-2008 half precision floating point format.
|
|
|
|
@c GGGGGGGGGGGGGGGGGGGGGGGGGG
|
|
@c HHHHHHHHHHHHHHHHHHHHHHHHHH
|
|
@c IIIIIIIIIIIIIIIIIIIIIIIIII
|
|
|
|
@cindex @code{.inst} directive, AArch64
|
|
@item .inst @var{expressions}
|
|
Inserts the expressions into the output as if they were instructions,
|
|
rather than data.
|
|
|
|
@c JJJJJJJJJJJJJJJJJJJJJJJJJJ
|
|
@c KKKKKKKKKKKKKKKKKKKKKKKKKK
|
|
@c LLLLLLLLLLLLLLLLLLLLLLLLLL
|
|
|
|
@cindex @code{.ltorg} directive, AArch64
|
|
@item .ltorg
|
|
This directive causes the current contents of the literal pool to be
|
|
dumped into the current section (which is assumed to be the .text
|
|
section) at the current location (aligned to a word boundary).
|
|
GAS maintains a separate literal pool for each section and each
|
|
sub-section. The @code{.ltorg} directive will only affect the literal
|
|
pool of the current section and sub-section. At the end of assembly
|
|
all remaining, un-empty literal pools will automatically be dumped.
|
|
|
|
Note - older versions of GAS would dump the current literal
|
|
pool any time a section change occurred. This is no longer done, since
|
|
it prevents accurate control of the placement of literal pools.
|
|
|
|
@c MMMMMMMMMMMMMMMMMMMMMMMMMM
|
|
|
|
@c NNNNNNNNNNNNNNNNNNNNNNNNNN
|
|
@c OOOOOOOOOOOOOOOOOOOOOOOOOO
|
|
|
|
@c PPPPPPPPPPPPPPPPPPPPPPPPPP
|
|
|
|
@cindex @code{.pool} directive, AArch64
|
|
@item .pool
|
|
This is a synonym for .ltorg.
|
|
|
|
@c QQQQQQQQQQQQQQQQQQQQQQQQQQ
|
|
@c RRRRRRRRRRRRRRRRRRRRRRRRRR
|
|
|
|
@cindex @code{.req} directive, AArch64
|
|
@item @var{name} .req @var{register name}
|
|
This creates an alias for @var{register name} called @var{name}. For
|
|
example:
|
|
|
|
@smallexample
|
|
foo .req w0
|
|
@end smallexample
|
|
|
|
ip0, ip1, lr and fp are automatically defined to
|
|
alias to X16, X17, X30 and X29 respectively.
|
|
|
|
@c SSSSSSSSSSSSSSSSSSSSSSSSSS
|
|
|
|
@c TTTTTTTTTTTTTTTTTTTTTTTTTT
|
|
|
|
@cindex @code{.tlsdescadd} directive, AArch64
|
|
@item @code{.tlsdescadd}
|
|
Emits a TLSDESC_ADD reloc on the next instruction.
|
|
|
|
@cindex @code{.tlsdesccall} directive, AArch64
|
|
@item @code{.tlsdesccall}
|
|
Emits a TLSDESC_CALL reloc on the next instruction.
|
|
|
|
@cindex @code{.tlsdescldr} directive, AArch64
|
|
@item @code{.tlsdescldr}
|
|
Emits a TLSDESC_LDR reloc on the next instruction.
|
|
|
|
@c UUUUUUUUUUUUUUUUUUUUUUUUUU
|
|
|
|
@cindex @code{.unreq} directive, AArch64
|
|
@item .unreq @var{alias-name}
|
|
This undefines a register alias which was previously defined using the
|
|
@code{req} directive. For example:
|
|
|
|
@smallexample
|
|
foo .req w0
|
|
.unreq foo
|
|
@end smallexample
|
|
|
|
An error occurs if the name is undefined. Note - this pseudo op can
|
|
be used to delete builtin in register name aliases (eg 'w0'). This
|
|
should only be done if it is really necessary.
|
|
|
|
@c VVVVVVVVVVVVVVVVVVVVVVVVVV
|
|
|
|
@cindex @code{.variant_pcs} directive, AArch64
|
|
@item .variant_pcs @var{symbol}
|
|
This directive marks @var{symbol} referencing a function that may
|
|
follow a variant procedure call standard with different register
|
|
usage convention from the base procedure call standard.
|
|
|
|
@c WWWWWWWWWWWWWWWWWWWWWWWWWW
|
|
@c XXXXXXXXXXXXXXXXXXXXXXXXXX
|
|
|
|
@cindex @code{.xword} directive, AArch64
|
|
@item .xword @var{expressions}
|
|
The @code{.xword} directive produces 64 bit values. This is the same
|
|
as the @code{.dword} directive.
|
|
|
|
@c YYYYYYYYYYYYYYYYYYYYYYYYYY
|
|
@c ZZZZZZZZZZZZZZZZZZZZZZZZZZ
|
|
|
|
@cindex @code{.cfi_b_key_frame} directive, AArch64
|
|
@item @code{.cfi_b_key_frame}
|
|
The @code{.cfi_b_key_frame} directive inserts a 'B' character into the CIE
|
|
corresponding to the current frame's FDE, meaning that its return address has
|
|
been signed with the B-key. If two frames are signed with differing keys then
|
|
they will not share the same CIE. This information is intended to be used by
|
|
the stack unwinder in order to properly authenticate return addresses.
|
|
|
|
@end table
|
|
|
|
@node AArch64 Opcodes
|
|
@section Opcodes
|
|
|
|
@cindex AArch64 opcodes
|
|
@cindex opcodes for AArch64
|
|
GAS implements all the standard AArch64 opcodes. It also
|
|
implements several pseudo opcodes, including several synthetic load
|
|
instructions.
|
|
|
|
@table @code
|
|
|
|
@cindex @code{LDR reg,=<expr>} pseudo op, AArch64
|
|
@item LDR =
|
|
@smallexample
|
|
ldr <register> , =<expression>
|
|
@end smallexample
|
|
|
|
The constant expression will be placed into the nearest literal pool (if it not
|
|
already there) and a PC-relative LDR instruction will be generated.
|
|
|
|
@end table
|
|
|
|
For more information on the AArch64 instruction set and assembly language
|
|
notation, see @samp{Arm Architecture Reference Manual for A-profile
|
|
architecture} available at @uref{https://developer.arm.com/}.
|
|
|
|
|
|
@node AArch64 Mapping Symbols
|
|
@section Mapping Symbols
|
|
|
|
The AArch64 ELF specification requires that special symbols be inserted
|
|
into object files to mark certain features:
|
|
|
|
@table @code
|
|
|
|
@cindex @code{$x}
|
|
@item $x
|
|
At the start of a region of code containing AArch64 instructions.
|
|
|
|
@cindex @code{$d}
|
|
@item $d
|
|
At the start of a region of data.
|
|
|
|
@end table
|