1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- This file documents the GNU Assembler "as". 4 5Copyright (C) 1991-2021 Free Software Foundation, Inc. 6 7Permission is granted to copy, distribute and/or modify this document 8under the terms of the GNU Free Documentation License, Version 1.3 9or any later version published by the Free Software Foundation; 10with no Invariant Sections, with no Front-Cover Texts, and with no 11Back-Cover Texts. A copy of the license is included in the 12section entitled "GNU Free Documentation License". 13 --> 14<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> 15<head> 16<title>Using as: Xtensa Directives</title> 17 18<meta name="description" content="Using as: Xtensa Directives"> 19<meta name="keywords" content="Using as: Xtensa Directives"> 20<meta name="resource-type" content="document"> 21<meta name="distribution" content="global"> 22<meta name="Generator" content="makeinfo"> 23<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 24<link href="index.html#Top" rel="start" title="Top"> 25<link href="AS-Index.html#AS-Index" rel="index" title="AS Index"> 26<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> 27<link href="Xtensa_002dDependent.html#Xtensa_002dDependent" rel="up" title="Xtensa-Dependent"> 28<link href="Schedule-Directive.html#Schedule-Directive" rel="next" title="Schedule Directive"> 29<link href="Xtensa-Immediate-Relaxation.html#Xtensa-Immediate-Relaxation" rel="previous" title="Xtensa Immediate Relaxation"> 30<style type="text/css"> 31<!-- 32a.summary-letter {text-decoration: none} 33blockquote.smallquotation {font-size: smaller} 34div.display {margin-left: 3.2em} 35div.example {margin-left: 3.2em} 36div.indentedblock {margin-left: 3.2em} 37div.lisp {margin-left: 3.2em} 38div.smalldisplay {margin-left: 3.2em} 39div.smallexample {margin-left: 3.2em} 40div.smallindentedblock {margin-left: 3.2em; font-size: smaller} 41div.smalllisp {margin-left: 3.2em} 42kbd {font-style:oblique} 43pre.display {font-family: inherit} 44pre.format {font-family: inherit} 45pre.menu-comment {font-family: serif} 46pre.menu-preformatted {font-family: serif} 47pre.smalldisplay {font-family: inherit; font-size: smaller} 48pre.smallexample {font-size: smaller} 49pre.smallformat {font-family: inherit; font-size: smaller} 50pre.smalllisp {font-size: smaller} 51span.nocodebreak {white-space:nowrap} 52span.nolinebreak {white-space:nowrap} 53span.roman {font-family:serif; font-weight:normal} 54span.sansserif {font-family:sans-serif; font-weight:normal} 55ul.no-bullet {list-style: none} 56--> 57</style> 58 59 60</head> 61 62<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> 63<a name="Xtensa-Directives"></a> 64<div class="header"> 65<p> 66Previous: <a href="Xtensa-Relaxation.html#Xtensa-Relaxation" accesskey="p" rel="previous">Xtensa Relaxation</a>, Up: <a href="Xtensa_002dDependent.html#Xtensa_002dDependent" accesskey="u" rel="up">Xtensa-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> 67</div> 68<hr> 69<a name="Directives-3"></a> 70<h4 class="subsection">9.55.5 Directives</h4> 71<a name="index-Xtensa-directives"></a> 72<a name="index-directives_002c-Xtensa"></a> 73 74<p>The Xtensa assembler supports a region-based directive syntax: 75</p> 76<div class="smallexample"> 77<pre class="smallexample"> .begin <var>directive</var> [<var>options</var>] 78 … 79 .end <var>directive</var> 80</pre></div> 81 82<p>All the Xtensa-specific directives that apply to a region of code use 83this syntax. 84</p> 85<p>The directive applies to code between the <code>.begin</code> and the 86<code>.end</code>. The state of the option after the <code>.end</code> reverts to 87what it was before the <code>.begin</code>. 88A nested <code>.begin</code>/<code>.end</code> region can further 89change the state of the directive without having to be aware of its 90outer state. For example, consider: 91</p> 92<div class="smallexample"> 93<pre class="smallexample"> .begin no-transform 94L: add a0, a1, a2 95</pre><pre class="smallexample"> .begin transform 96M: add a0, a1, a2 97 .end transform 98</pre><pre class="smallexample">N: add a0, a1, a2 99 .end no-transform 100</pre></div> 101 102<p>The <code>ADD</code> opcodes at <code>L</code> and <code>N</code> in the outer 103<code>no-transform</code> region both result in <code>ADD</code> machine instructions, 104but the assembler selects an <code>ADD.N</code> instruction for the 105<code>ADD</code> at <code>M</code> in the inner <code>transform</code> region. 106</p> 107<p>The advantage of this style is that it works well inside macros which can 108preserve the context of their callers. 109</p> 110<p>The following directives are available: 111</p><table class="menu" border="0" cellspacing="0"> 112<tr><td align="left" valign="top">• <a href="Schedule-Directive.html#Schedule-Directive" accesskey="1">Schedule Directive</a>:</td><td> </td><td align="left" valign="top">Enable instruction scheduling. 113</td></tr> 114<tr><td align="left" valign="top">• <a href="Longcalls-Directive.html#Longcalls-Directive" accesskey="2">Longcalls Directive</a>:</td><td> </td><td align="left" valign="top">Use Indirect Calls for Greater Range. 115</td></tr> 116<tr><td align="left" valign="top">• <a href="Transform-Directive.html#Transform-Directive" accesskey="3">Transform Directive</a>:</td><td> </td><td align="left" valign="top">Disable All Assembler Transformations. 117</td></tr> 118<tr><td align="left" valign="top">• <a href="Literal-Directive.html#Literal-Directive" accesskey="4">Literal Directive</a>:</td><td> </td><td align="left" valign="top">Intermix Literals with Instructions. 119</td></tr> 120<tr><td align="left" valign="top">• <a href="Literal-Position-Directive.html#Literal-Position-Directive" accesskey="5">Literal Position Directive</a>:</td><td> </td><td align="left" valign="top">Specify Inline Literal Pool Locations. 121</td></tr> 122<tr><td align="left" valign="top">• <a href="Literal-Prefix-Directive.html#Literal-Prefix-Directive" accesskey="6">Literal Prefix Directive</a>:</td><td> </td><td align="left" valign="top">Specify Literal Section Name Prefix. 123</td></tr> 124<tr><td align="left" valign="top">• <a href="Absolute-Literals-Directive.html#Absolute-Literals-Directive" accesskey="7">Absolute Literals Directive</a>:</td><td> </td><td align="left" valign="top">Control PC-Relative vs. Absolute Literals. 125</td></tr> 126</table> 127 128<hr> 129<div class="header"> 130<p> 131Previous: <a href="Xtensa-Relaxation.html#Xtensa-Relaxation" accesskey="p" rel="previous">Xtensa Relaxation</a>, Up: <a href="Xtensa_002dDependent.html#Xtensa_002dDependent" accesskey="u" rel="up">Xtensa-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> 132</div> 133 134 135 136</body> 137</html> 138