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<title>Using as: MIPS ISA</title>
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<a name="MIPS-ISA"></a>
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<div class="header">
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<p>
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Next: <a href="MIPS-assembly-options.html#MIPS-assembly-options" accesskey="n" rel="next">MIPS assembly options</a>, Previous: <a href="MIPS-Small-Data.html#MIPS-Small-Data" accesskey="p" rel="previous">MIPS Small Data</a>, Up: <a href="MIPS_002dDependent.html#MIPS_002dDependent" accesskey="u" rel="up">MIPS-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
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<a name="Directives-to-override-the-ISA-level"></a>
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<h4 class="subsection">9.27.5 Directives to override the ISA level</h4>
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<a name="index-MIPS-ISA-override"></a>
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<a name="index-_002eset-mipsn"></a>
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<p><small>GNU</small> <code>as</code> supports an additional directive to change
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the MIPS Instruction Set Architecture level on the fly: <code>.set
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mips<var>n</var></code>. <var>n</var> should be a number from 0 to 5, or 32, 32r2, 32r3,
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32r5, 32r6, 64, 64r2, 64r3, 64r5 or 64r6.
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The values other than 0 make the assembler accept instructions
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for the corresponding ISA level, from that point on in the
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assembly. <code>.set mips<var>n</var></code> affects not only which instructions
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are permitted, but also how certain macros are expanded. <code>.set
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mips0</code> restores the ISA level to its original level: either the
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level you selected with command-line options, or the default for your
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configuration. You can use this feature to permit specific MIPS III
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instructions while assembling in 32 bit mode. Use this directive with
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care!
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</p>
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<a name="index-MIPS-CPU-override"></a>
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<a name="index-_002eset-arch_003dcpu"></a>
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<p>The <code>.set arch=<var>cpu</var></code> directive provides even finer control.
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It changes the effective CPU target and allows the assembler to use
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instructions specific to a particular CPU. All CPUs supported by the
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‘<samp>-march</samp>’ command-line option are also selectable by this directive.
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The original value is restored by <code>.set arch=default</code>.
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</p>
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<p>The directive <code>.set mips16</code> puts the assembler into MIPS 16 mode,
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in which it will assemble instructions for the MIPS 16 processor. Use
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<code>.set nomips16</code> to return to normal 32 bit mode.
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</p>
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<p>Traditional MIPS assemblers do not support this directive.
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</p>
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<p>The directive <code>.set micromips</code> puts the assembler into microMIPS mode,
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in which it will assemble instructions for the microMIPS processor. Use
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<code>.set nomicromips</code> to return to normal 32 bit mode.
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</p>
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<p>Traditional MIPS assemblers do not support this directive.
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</p>
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<hr>
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<div class="header">
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<p>
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Next: <a href="MIPS-assembly-options.html#MIPS-assembly-options" accesskey="n" rel="next">MIPS assembly options</a>, Previous: <a href="MIPS-Small-Data.html#MIPS-Small-Data" accesskey="p" rel="previous">MIPS Small Data</a>, Up: <a href="MIPS_002dDependent.html#MIPS_002dDependent" accesskey="u" rel="up">MIPS-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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