Using as: ARM Options

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#### 9.4.1 Options

`-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: `arm1`, `arm2`, `arm250`, `arm3`, `arm6`, `arm60`, `arm600`, `arm610`, `arm620`, `arm7`, `arm7m`, `arm7d`, `arm7dm`, `arm7di`, `arm7dmi`, `arm70`, `arm700`, `arm700i`, `arm710`, `arm710t`, `arm720`, `arm720t`, `arm740t`, `arm710c`, `arm7100`, `arm7500`, `arm7500fe`, `arm7t`, `arm7tdmi`, `arm7tdmi-s`, `arm8`, `arm810`, `strongarm`, `strongarm1`, `strongarm110`, `strongarm1100`, `strongarm1110`, `arm9`, `arm920`, `arm920t`, `arm922t`, `arm940t`, `arm9tdmi`, `fa526` (Faraday FA526 processor), `fa626` (Faraday FA626 processor), `arm9e`, `arm926e`, `arm926ej-s`, `arm946e-r0`, `arm946e`, `arm946e-s`, `arm966e-r0`, `arm966e`, `arm966e-s`, `arm968e-s`, `arm10t`, `arm10tdmi`, `arm10e`, `arm1020`, `arm1020t`, `arm1020e`, `arm1022e`, `arm1026ej-s`, `fa606te` (Faraday FA606TE processor), `fa616te` (Faraday FA616TE processor), `fa626te` (Faraday FA626TE processor), `fmp626` (Faraday FMP626 processor), `fa726te` (Faraday FA726TE processor), `arm1136j-s`, `arm1136jf-s`, `arm1156t2-s`, `arm1156t2f-s`, `arm1176jz-s`, `arm1176jzf-s`, `mpcore`, `mpcorenovfp`, `cortex-a5`, `cortex-a7`, `cortex-a8`, `cortex-a9`, `cortex-a15`, `cortex-r4`, `cortex-r4f`, `cortex-r5`, `cortex-r7`, `cortex-m4`, `cortex-m3`, `cortex-m1`, `cortex-m0`, `cortex-m0plus`, `ep9312` (ARM920 with Cirrus Maverick coprocessor), `i80200` (Intel XScale processor) `iwmmxt` (Intel(r) XScale processor with Wireless MMX(tm) technology coprocessor) and `xscale`. The special name `all` may be used to allow the assembler to accept instructions valid for any ARM processor.

  In addition to the basic instruction set, the assembler can be told to accept various extension mnemonics that extend the processor using the co-processor instruction space. For example, `-mcpu=arm920+maverick` is equivalent to specifying `-mcpu=ep9312`.

  Multiple extensions may be specified, separated by a `+`. The extensions should be specified in ascending alphabetical order.

  Some extensions may be restricted to particular architectures; this is documented in the list of extensions below.

  Extension mnemonics may also be removed from those the assembler accepts. This is done be prepending `no` to the option that adds the extension. Extensions that are removed should be listed after all extensions which have been added, again in ascending alphabetical order. For example, `-mcpu=ep9312+nomaverick` is equivalent to specifying `-mcpu=arm920`.

  The following extensions are currently supported: `crypto` (Cryptography Extensions for v8-A architecture, implies `fp+simd`), `fp` (Floating Point Extensions for v8-A architecture), `idiv` (Integer Divide Extensions for v7-A and v7-R architectures), `iwmmxt`, `iwmmxt2`, `maverick`, `mp` (Multiprocessing Extensions for v7-A and v7-R architectures), `os` (Operating System for v6M architecture), `sec` (Security Extensions for v6K and v7-A architectures), `simd` (Advanced SIMD Extensions for v8-A architecture, implies `fp`), `virt` (Virtualization Extensions for v7-A architecture, implies `idiv`), `pan` (Priviliged Access Never Extensions for v8-A architecture), `rdma` (ARMv8.1 Advanced SIMD extensions for v8-A architecture, implies `simd`) and `xscale`.

`-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: `armv1`, `armv2`, `armv2a`, `armv2s`, `armv3`, `armv3m`, `armv4`, `armv4xm`, `armv4t`, `armv4txm`, `armv5`, `armv5t`, `armv5txm`, `armv5te`, `armv5texp`, `armv6`, `armv6j`, `armv6k`, `armv6z`, `armv6zk`, `armv6-m`, `armv6s-m`, `armv7`, `armv7-a`, `armv7ve`, `armv7-r`, `armv7-m`, `armv7e-m`, `armv8-a`, `armv8.1-a`, `armv8.2-a`, `iwmmxt` and `xscale`. If both `-mcpu` and `-march` are specified, the assembler will use the setting for `-mcpu`.

  The architecture option can be extended with the same instruction set extension options as the `-mcpu` option.

`-mfpu=floating-point-format`

  This option specifies the floating point format to assemble for. The assembler will issue an error message if an attempt is made to assemble an instruction which will not execute on the target floating point unit. The following format options are recognized: `softfpa`, `fpe`, `fpe2`, `fpe3`, `fpa`, `fpa10`, `fpa11`, `arm7500fe`, `softvfp`, `softvfp+vfp`, `vfp`, `vfp10`, `vfp10-r0`, `vfp9`, `vfpxd`, `vfpv2`, `vfpv3`, `vfpv3-fp16`, `vfpv3-d16`, `vfpv3-d16-fp16`, `vfpv3xd`, `vfpv3xd-d16`, `vfpv4`, `vfpv4-d16`, `fpv4-sp-d16`, `fp-armv8`, `arm1020t`, `arm1020e`, `arm1136jf-s`, `maverick`, `neon`, `neon-vfpv4`, `neon-fp-armv8`, `crypto-neon-fp-armv8`, `neon-fp-armv8.1` and `crypto-neon-fp-armv8.1`.

  In addition to determining which instructions are assembled, this option also affects the way in which the `.double` assembler directive behaves when assembling little-endian code.

  The default is dependent on the processor selected. For Architecture 5 or later, the default is to assembler for VFP instructions; for earlier architectures the default is to assemble for FPA instructions.

`-mthumb`

  This option specifies that the assembler should start assembling Thumb instructions; that is, it should behave as though the file starts with a `.code 16` directive.

`-mthumb-interwork`

  This option specifies that the output generated by the assembler should be marked as supporting interworking.

`-mimplicit-it=never`
`-mimplicit-it=always`
`-mimplicit-it=arm`
`-mimplicit-it=thumb`

  The `-mimplicit-it` option controls the behavior of the assembler when conditional instructions are not enclosed in IT blocks. There are four possible behaviors. If `never` is specified, such constructs cause a warning in ARM code and an error in Thumb-2 code. If `always` is specified, such constructs are accepted in both ARM and Thumb-2 code, where the IT instruction is added implicitly. If `arm` is specified, such constructs are accepted in ARM code and cause an error in Thumb-2 code. If `thumb` is specified, such constructs cause a warning in ARM code and are accepted in Thumb-2 code. If you omit this option, the behavior is equivalent to `-mimplicit-it=arm`.

`-mapcs-26`
`-mapcs-32`

  These options specify that the output generated by the assembler should be marked as supporting the indicated version of the Arm Procedure. Calling Standard.

`-matpcs`

  This option specifies that the output generated by the assembler should be marked as supporting the Arm/Thumb Procedure Calling Standard. If enabled this option will cause the assembler to create an empty debugging section in the object file called .arm.atpcs. Debuggers can use this to determine the ABI being used by.

`-mapcs-float`

  This indicates the floating point variant of the APCS should be used. In this variant floating point arguments are passed in FP registers rather than integer registers.

`-mapcs-reentrant`

  This indicates that the reentrant variant of the APCS should be used. This variant supports position independent code.

`-mfloat-abi=abi`

  This option specifies that the output generated by the assembler should be marked as using specified floating point ABI. The following values are recognized: `soft`, `softfp` and `hard`.

`-meabi=ver`

  This option specifies which EABI version the produced object files should conform to. The following values are recognized: `gnu`, `4` and `5`.

`-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.

`-k`

  This option specifies that the output of the assembler should be marked as position-independent code (PIC).

`--fix-v4bx`

  Allow `BX` instructions in ARMv4 code. This is intended for use with the linker option of the same name.

`-mwarn-deprecated`
`-mno-warn-deprecated`

  Enable or disable warnings about using deprecated options or features. The default is to warn.

`-mccs`

  Turns on CodeComposer Studio assembly syntax compatibility mode.

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