<html lang="en">
<head>
<title>MIPS ISA - Using as</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Using as">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="MIPS_002dDependent.html#MIPS_002dDependent" title="MIPS-Dependent">
<link rel="prev" href="MIPS-Small-Data.html#MIPS-Small-Data" title="MIPS Small Data">
<link rel="next" href="MIPS-assembly-options.html#MIPS-assembly-options" title="MIPS assembly options">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
This file documents the GNU Assembler "as".

Copyright (C) 1991-2019 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the
section entitled ``GNU Free Documentation License''.

-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
  pre.display { font-family:inherit }
  pre.format  { font-family:inherit }
  pre.smalldisplay { font-family:inherit; font-size:smaller }
  pre.smallformat  { font-family:inherit; font-size:smaller }
  pre.smallexample { font-size:smaller }
  pre.smalllisp    { font-size:smaller }
  span.sc    { font-variant:small-caps }
  span.roman { font-family:serif; font-weight:normal; } 
  span.sansserif { font-family:sans-serif; font-weight:normal; } 
--></style>
</head>
<body>
<div class="node">
<a name="MIPS-ISA"></a>
<p>
Next:&nbsp;<a rel="next" accesskey="n" href="MIPS-assembly-options.html#MIPS-assembly-options">MIPS assembly options</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="MIPS-Small-Data.html#MIPS-Small-Data">MIPS Small Data</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="MIPS_002dDependent.html#MIPS_002dDependent">MIPS-Dependent</a>
<hr>
</div>

<h4 class="subsection">9.27.5 Directives to override the ISA level</h4>

<p><a name="index-MIPS-ISA-override-1580"></a><a name="index-g_t_0040code_007b_002eset-mips_0040var_007bn_007d_007d-1581"></a><span class="sc">gnu</span> <code>as</code> supports an additional directive to change
the MIPS Instruction Set Architecture level on the fly: <code>.set
mips</code><var>n</var>.  <var>n</var> should be a number from 0 to 5, or 32, 32r2, 32r3,
32r5, 32r6, 64, 64r2, 64r3, 64r5 or 64r6. 
The values other than 0 make the assembler accept instructions
for the corresponding ISA level, from that point on in the
assembly.  <code>.set mips</code><var>n</var> affects not only which instructions
are permitted, but also how certain macros are expanded.  <code>.set
mips0</code> restores the ISA level to its original level: either the
level you selected with command-line options, or the default for your
configuration.  You can use this feature to permit specific MIPS III
instructions while assembling in 32 bit mode.  Use this directive with
care!

   <p><a name="index-MIPS-CPU-override-1582"></a><a name="index-g_t_0040code_007b_002eset-arch_003d_0040var_007bcpu_007d_007d-1583"></a>The <code>.set arch=</code><var>cpu</var> directive provides even finer control. 
It changes the effective CPU target and allows the assembler to use
instructions specific to a particular CPU.  All CPUs supported by the
&lsquo;<samp><span class="samp">-march</span></samp>&rsquo; command-line option are also selectable by this directive. 
The original value is restored by <code>.set arch=default</code>.

   <p>The directive <code>.set mips16</code> puts the assembler into MIPS 16 mode,
in which it will assemble instructions for the MIPS 16 processor.  Use
<code>.set nomips16</code> to return to normal 32 bit mode.

   <p>Traditional MIPS assemblers do not support this directive.

   <p>The directive <code>.set micromips</code> puts the assembler into microMIPS mode,
in which it will assemble instructions for the microMIPS processor.  Use
<code>.set nomicromips</code> to return to normal 32 bit mode.

   <p>Traditional MIPS assemblers do not support this directive.

   </body></html>