The SPARC chip family includes several successive levels, using the same core instruction set, but including a few additional instructions at each level. There are exceptions to this however. For details on what instructions each variant supports, please see the chip's architecture reference manual.
By default, as assumes the core instruction set (SPARC v6), but "bumps" the architecture level as needed: it switches to successively higher architectures as it encounters instructions that only exist in the higher levels.
If not configured for SPARC v9 (sparc64-*-*) GAS will not bump passed sparclite by default, an option must be passed to enable the v9 instructions.
GAS treats sparclite as being compatible with v8, unless an architecture is explicitly requested. SPARC v9 is always incompatible with sparclite.
Use one of the -A options to select one of the SPARC architectures explicitly. If you select an architecture explicitly, as reports a fatal error if it encounters an instruction or feature requiring an incompatible or higher level.
-Av8plus and -Av8plusa select a 32 bit environment.
-Av9 and -Av9a select a 64 bit environment and are not available unless GAS is explicitly configured with 64 bit environment support.
-Av8plusa and -Av9a enable the SPARC V9 instruction set with UltraSPARC extensions.
For compatibility with the Solaris v9 assembler. These options are equivalent to -Av8plus and -Av8plusa, respectively.
Warn whenever it is necessary to switch to another level. If an architecture level is explicitly requested, GAS will not issue warnings until that level is reached, and will then bump the level as required (except between incompatible levels).
Select the word size, either 32 bits or 64 bits. These options are only available with the ELF object file format, and require that the necessary BFD support has been included.