You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
231 lines
10 KiB
HTML
231 lines
10 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- 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".
|
|
-->
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>Alpha Directives (Using as)</title>
|
|
|
|
<meta name="description" content="Alpha Directives (Using as)">
|
|
<meta name="keywords" content="Alpha Directives (Using as)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<link href="index.html#Top" rel="start" title="Top">
|
|
<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="Alpha_002dDependent.html#Alpha_002dDependent" rel="up" title="Alpha-Dependent">
|
|
<link href="Alpha-Opcodes.html#Alpha-Opcodes" rel="next" title="Alpha Opcodes">
|
|
<link href="Alpha-Floating-Point.html#Alpha-Floating-Point" rel="prev" title="Alpha Floating Point">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smalllisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
|
pre.smallexample {font-size: smaller}
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
|
pre.smalllisp {font-size: smaller}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<a name="Alpha-Directives"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Alpha-Opcodes.html#Alpha-Opcodes" accesskey="n" rel="next">Alpha Opcodes</a>, Previous: <a href="Alpha-Floating-Point.html#Alpha-Floating-Point" accesskey="p" rel="prev">Alpha Floating Point</a>, Up: <a href="Alpha_002dDependent.html#Alpha_002dDependent" accesskey="u" rel="up">Alpha-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>
|
|
</div>
|
|
<hr>
|
|
<a name="Alpha-Assembler-Directives"></a>
|
|
<h4 class="subsection">9.2.5 Alpha Assembler Directives</h4>
|
|
|
|
<p><code>as</code> for the Alpha supports many additional directives for
|
|
compatibility with the native assembler. This section describes them only
|
|
briefly.
|
|
</p>
|
|
<a name="index-Alpha_002donly-directives"></a>
|
|
<p>These are the additional directives in <code>as</code> for the Alpha:
|
|
</p>
|
|
<dl compact="compact">
|
|
<dt><code>.arch <var>cpu</var></code></dt>
|
|
<dd><p>Specifies the target processor. This is equivalent to the
|
|
<samp>-m<var>cpu</var></samp> command-line option. See <a href="Alpha-Options.html#Alpha-Options">Options</a>,
|
|
for a list of values for <var>cpu</var>.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.ent <var>function</var>[, <var>n</var>]</code></dt>
|
|
<dd><p>Mark the beginning of <var>function</var>. An optional number may follow for
|
|
compatibility with the OSF/1 assembler, but is ignored. When generating
|
|
<code>.mdebug</code> information, this will create a procedure descriptor for
|
|
the function. In ELF, it will mark the symbol as a function a-la the
|
|
generic <code>.type</code> directive.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.end <var>function</var></code></dt>
|
|
<dd><p>Mark the end of <var>function</var>. In ELF, it will set the size of the symbol
|
|
a-la the generic <code>.size</code> directive.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.mask <var>mask</var>, <var>offset</var></code></dt>
|
|
<dd><p>Indicate which of the integer registers are saved in the current
|
|
function’s stack frame. <var>mask</var> is interpreted a bit mask in which
|
|
bit <var>n</var> set indicates that register <var>n</var> is saved. The registers
|
|
are saved in a block located <var>offset</var> bytes from the <em>canonical
|
|
frame address</em> (CFA) which is the value of the stack pointer on entry to
|
|
the function. The registers are saved sequentially, except that the
|
|
return address register (normally <code>$26</code>) is saved first.
|
|
</p>
|
|
<p>This and the other directives that describe the stack frame are
|
|
currently only used when generating <code>.mdebug</code> information. They
|
|
may in the future be used to generate DWARF2 <code>.debug_frame</code> unwind
|
|
information for hand written assembly.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.fmask <var>mask</var>, <var>offset</var></code></dt>
|
|
<dd><p>Indicate which of the floating-point registers are saved in the current
|
|
stack frame. The <var>mask</var> and <var>offset</var> parameters are interpreted
|
|
as with <code>.mask</code>.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.frame <var>framereg</var>, <var>frameoffset</var>, <var>retreg</var>[, <var>argoffset</var>]</code></dt>
|
|
<dd><p>Describes the shape of the stack frame. The frame pointer in use is
|
|
<var>framereg</var>; normally this is either <code>$fp</code> or <code>$sp</code>. The
|
|
frame pointer is <var>frameoffset</var> bytes below the CFA. The return
|
|
address is initially located in <var>retreg</var> until it is saved as
|
|
indicated in <code>.mask</code>. For compatibility with OSF/1 an optional
|
|
<var>argoffset</var> parameter is accepted and ignored. It is believed to
|
|
indicate the offset from the CFA to the saved argument registers.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.prologue <var>n</var></code></dt>
|
|
<dd><p>Indicate that the stack frame is set up and all registers have been
|
|
spilled. The argument <var>n</var> indicates whether and how the function
|
|
uses the incoming <em>procedure vector</em> (the address of the called
|
|
function) in <code>$27</code>. 0 indicates that <code>$27</code> is not used; 1
|
|
indicates that the first two instructions of the function use <code>$27</code>
|
|
to perform a load of the GP register; 2 indicates that <code>$27</code> is
|
|
used in some non-standard way and so the linker cannot elide the load of
|
|
the procedure vector during relaxation.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.usepv <var>function</var>, <var>which</var></code></dt>
|
|
<dd><p>Used to indicate the use of the <code>$27</code> register, similar to
|
|
<code>.prologue</code>, but without the other semantics of needing to
|
|
be inside an open <code>.ent</code>/<code>.end</code> block.
|
|
</p>
|
|
<p>The <var>which</var> argument should be either <code>no</code>, indicating that
|
|
<code>$27</code> is not used, or <code>std</code>, indicating that the first two
|
|
instructions of the function perform a GP load.
|
|
</p>
|
|
<p>One might use this directive instead of <code>.prologue</code> if you are
|
|
also using dwarf2 CFI directives.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.gprel32 <var>expression</var></code></dt>
|
|
<dd><p>Computes the difference between the address in <var>expression</var> and the
|
|
GP for the current object file, and stores it in 4 bytes. In addition
|
|
to being smaller than a full 8 byte address, this also does not require
|
|
a dynamic relocation when used in a shared library.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.t_floating <var>expression</var></code></dt>
|
|
<dd><p>Stores <var>expression</var> as an <small>IEEE</small> double precision value.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.s_floating <var>expression</var></code></dt>
|
|
<dd><p>Stores <var>expression</var> as an <small>IEEE</small> single precision value.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.f_floating <var>expression</var></code></dt>
|
|
<dd><p>Stores <var>expression</var> as a VAX F format value.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.g_floating <var>expression</var></code></dt>
|
|
<dd><p>Stores <var>expression</var> as a VAX G format value.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.d_floating <var>expression</var></code></dt>
|
|
<dd><p>Stores <var>expression</var> as a VAX D format value.
|
|
</p>
|
|
</dd>
|
|
<dt><code>.set <var>feature</var></code></dt>
|
|
<dd><p>Enables or disables various assembler features. Using the positive
|
|
name of the feature enables while using ‘<samp>no<var>feature</var></samp>’ disables.
|
|
</p>
|
|
<dl compact="compact">
|
|
<dt><code>at</code></dt>
|
|
<dd><p>Indicates that macro expansions may clobber the <em>assembler
|
|
temporary</em> (<code>$at</code> or <code>$28</code>) register. Some macros may not be
|
|
expanded without this and will generate an error message if <code>noat</code>
|
|
is in effect. When <code>at</code> is in effect, a warning will be generated
|
|
if <code>$at</code> is used by the programmer.
|
|
</p>
|
|
</dd>
|
|
<dt><code>macro</code></dt>
|
|
<dd><p>Enables the expansion of macro instructions. Note that variants of real
|
|
instructions, such as <code>br label</code> vs <code>br $31,label</code> are
|
|
considered alternate forms and not macros.
|
|
</p>
|
|
</dd>
|
|
<dt><code>move</code></dt>
|
|
<dt><code>reorder</code></dt>
|
|
<dt><code>volatile</code></dt>
|
|
<dd><p>These control whether and how the assembler may re-order instructions.
|
|
Accepted for compatibility with the OSF/1 assembler, but <code>as</code>
|
|
does not do instruction scheduling, so these features are ignored.
|
|
</p></dd>
|
|
</dl>
|
|
</dd>
|
|
</dl>
|
|
|
|
<p>The following directives are recognized for compatibility with the OSF/1
|
|
assembler but are ignored.
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">.proc .aproc
|
|
.reguse .livereg
|
|
.option .aent
|
|
.ugen .eflag
|
|
.alias .noalias
|
|
</pre></div>
|
|
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Alpha-Opcodes.html#Alpha-Opcodes" accesskey="n" rel="next">Alpha Opcodes</a>, Previous: <a href="Alpha-Floating-Point.html#Alpha-Floating-Point" accesskey="p" rel="prev">Alpha Floating Point</a>, Up: <a href="Alpha_002dDependent.html#Alpha_002dDependent" accesskey="u" rel="up">Alpha-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>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|