SPARC Dependent Features

Options

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.

-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite

-Av8plus | -Av8plusa | -Av9 | -Av9a

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.

-xarch=v8plus | -xarch=v8plusa

For compatibility with the Solaris v9 assembler. These options are equivalent to -Av8plus and -Av8plusa, respectively.

-bump

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).

-32 | -64

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.

Enforcing aligned data

SPARC GAS normally permits data to be misaligned. For example, it permits the .long pseudo-op to be used on a byte boundary. However, the native SunOS and Solaris assemblers issue an error when they see misaligned data.

You can use the --enforce-aligned-data option to make SPARC GAS also issue an error about misaligned data, just as the SunOS and Solaris assemblers do.

The --enforce-aligned-data option is not the default because gcc issues misaligned data pseudo-ops when it initializes certain packed data structures (structures defined using the packed attribute). You may have to assemble with GAS in order to initialize packed data structures in your own code.

Floating Point

The Sparc uses IEEE floating-point numbers.

Sparc Machine Directives

The Sparc version of as supports the following additional machine directives:

.align

This must be followed by the desired alignment in bytes.

.common

This must be followed by a symbol name, a positive number, and "bss". This behaves somewhat like .comm, but the syntax is different.

.half

This is functionally identical to .short.

.proc

This directive is ignored. Any text following it on the same line is also ignored.

.reserve

This must be followed by a symbol name, a positive number, and "bss". This behaves somewhat like .lcomm, but the syntax is different.

.seg

This must be followed by "text", "data", or "data1". It behaves like .text, .data, or .data 1.

.skip

This is functionally identical to the .space directive.

.word

On the Sparc, the .word directive produces 32 bit values, instead of the 16 bit values it produces on many other machines.

.xword

On the Sparc V9 processor, the .xword directive produces 64 bit values.

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