toolchain/gcc-linaro-6.3.1-2017.02-x8.../share/doc/as.html/Sparc_002dConstants.html

201 lines
9.0 KiB
HTML
Raw Normal View History

2024-03-22 05:10:17 +00:00
<!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) 1991-2016 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 5.2, http://www.gnu.org/software/texinfo/ -->
<head>
<title>Using as: Sparc-Constants</title>
<meta name="description" content="Using as: Sparc-Constants">
<meta name="keywords" content="Using as: Sparc-Constants">
<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="Sparc_002dSyntax.html#Sparc_002dSyntax" rel="up" title="Sparc-Syntax">
<link href="Sparc_002dRelocs.html#Sparc_002dRelocs" rel="next" title="Sparc-Relocs">
<link href="Sparc_002dRegs.html#Sparc_002dRegs" rel="prev" title="Sparc-Regs">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
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.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>
</head>
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="Sparc_002dConstants"></a>
<div class="header">
<p>
Next: <a href="Sparc_002dRelocs.html#Sparc_002dRelocs" accesskey="n" rel="next">Sparc-Relocs</a>, Previous: <a href="Sparc_002dRegs.html#Sparc_002dRegs" accesskey="p" rel="prev">Sparc-Regs</a>, Up: <a href="Sparc_002dSyntax.html#Sparc_002dSyntax" accesskey="u" rel="up">Sparc-Syntax</a> &nbsp; [<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="Constants-2"></a>
<h4 class="subsubsection">9.42.3.3 Constants</h4>
<a name="index-Sparc-constants"></a>
<a name="index-constants_002c-Sparc"></a>
<p>Several Sparc instructions take an immediate operand field for
which mnemonic names exist. Two such examples are &lsquo;<samp>membar</samp>&rsquo;
and &lsquo;<samp>prefetch</samp>&rsquo;. Another example are the set of V9
memory access instruction that allow specification of an
address space identifier.
</p>
<p>The &lsquo;<samp>membar</samp>&rsquo; instruction specifies a memory barrier that is
the defined by the operand which is a bitmask. The supported
mask mnemonics are:
</p>
<ul>
<li> &lsquo;<samp>#Sync</samp>&rsquo; requests that all operations (including nonmemory
reference operations) appearing prior to the <code>membar</code> must have
been performed and the effects of any exceptions become visible before
any instructions after the <code>membar</code> may be initiated. This
corresponds to <code>membar</code> cmask field bit 2.
</li><li> &lsquo;<samp>#MemIssue</samp>&rsquo; requests that all memory reference operations
appearing prior to the <code>membar</code> must have been performed before
any memory operation after the <code>membar</code> may be initiated. This
corresponds to <code>membar</code> cmask field bit 1.
</li><li> &lsquo;<samp>#Lookaside</samp>&rsquo; requests that a store appearing prior to the
<code>membar</code> must complete before any load following the
<code>membar</code> referencing the same address can be initiated. This
corresponds to <code>membar</code> cmask field bit 0.
</li><li> &lsquo;<samp>#StoreStore</samp>&rsquo; defines that the effects of all stores appearing
prior to the <code>membar</code> instruction must be visible to all
processors before the effect of any stores following the
<code>membar</code>. Equivalent to the deprecated <code>stbar</code> instruction.
This corresponds to <code>membar</code> mmask field bit 3.
</li><li> &lsquo;<samp>#LoadStore</samp>&rsquo; defines all loads appearing prior to the
<code>membar</code> instruction must have been performed before the effect
of any stores following the <code>membar</code> is visible to any other
processor. This corresponds to <code>membar</code> mmask field bit 2.
</li><li> &lsquo;<samp>#StoreLoad</samp>&rsquo; defines that the effects of all stores appearing
prior to the <code>membar</code> instruction must be visible to all
processors before loads following the <code>membar</code> may be performed.
This corresponds to <code>membar</code> mmask field bit 1.
</li><li> &lsquo;<samp>#LoadLoad</samp>&rsquo; defines that all loads appearing prior to the
<code>membar</code> instruction must have been performed before any loads
following the <code>membar</code> may be performed. This corresponds to
<code>membar</code> mmask field bit 0.
</li></ul>
<p>These values can be ored together, for example:
</p>
<div class="example">
<pre class="example">membar #Sync
membar #StoreLoad | #LoadLoad
membar #StoreLoad | #StoreStore
</pre></div>
<p>The <code>prefetch</code> and <code>prefetcha</code> instructions take a prefetch
function code. The following prefetch function code constant
mnemonics are available:
</p>
<ul>
<li> &lsquo;<samp>#n_reads</samp>&rsquo; requests a prefetch for several reads, and corresponds
to a prefetch function code of 0.
<p>&lsquo;<samp>#one_read</samp>&rsquo; requests a prefetch for one read, and corresponds
to a prefetch function code of 1.
</p>
<p>&lsquo;<samp>#n_writes</samp>&rsquo; requests a prefetch for several writes (and possibly
reads), and corresponds to a prefetch function code of 2.
</p>
<p>&lsquo;<samp>#one_write</samp>&rsquo; requests a prefetch for one write, and corresponds
to a prefetch function code of 3.
</p>
<p>&lsquo;<samp>#page</samp>&rsquo; requests a prefetch page, and corresponds to a prefetch
function code of 4.
</p>
<p>&lsquo;<samp>#invalidate</samp>&rsquo; requests a prefetch invalidate, and corresponds to
a prefetch function code of 16.
</p>
<p>&lsquo;<samp>#unified</samp>&rsquo; requests a prefetch to the nearest unified cache, and
corresponds to a prefetch function code of 17.
</p>
<p>&lsquo;<samp>#n_reads_strong</samp>&rsquo; requests a strong prefetch for several reads,
and corresponds to a prefetch function code of 20.
</p>
<p>&lsquo;<samp>#one_read_strong</samp>&rsquo; requests a strong prefetch for one read,
and corresponds to a prefetch function code of 21.
</p>
<p>&lsquo;<samp>#n_writes_strong</samp>&rsquo; requests a strong prefetch for several writes,
and corresponds to a prefetch function code of 22.
</p>
<p>&lsquo;<samp>#one_write_strong</samp>&rsquo; requests a strong prefetch for one write,
and corresponds to a prefetch function code of 23.
</p>
<p>Onle one prefetch code may be specified. Here are some examples:
</p>
<div class="example">
<pre class="example">prefetch [%l0 + %l2], #one_read
prefetch [%g2 + 8], #n_writes
prefetcha [%g1] 0x8, #unified
prefetcha [%o0 + 0x10] %asi, #n_reads
</pre></div>
<p>The actual behavior of a given prefetch function code is processor
specific. If a processor does not implement a given prefetch
function code, it will treat the prefetch instruction as a nop.
</p>
<p>For instructions that accept an immediate address space identifier,
<code>as</code> provides many mnemonics corresponding to
V9 defined as well as UltraSPARC and Niagara extended values.
For example, &lsquo;<samp>#ASI_P</samp>&rsquo; and &lsquo;<samp>#ASI_BLK_INIT_QUAD_LDD_AIUS</samp>&rsquo;.
See the V9 and processor specific manuals for details.
</p>
</li></ul>
<hr>
<div class="header">
<p>
Next: <a href="Sparc_002dRelocs.html#Sparc_002dRelocs" accesskey="n" rel="next">Sparc-Relocs</a>, Previous: <a href="Sparc_002dRegs.html#Sparc_002dRegs" accesskey="p" rel="prev">Sparc-Regs</a>, Up: <a href="Sparc_002dSyntax.html#Sparc_002dSyntax" accesskey="u" rel="up">Sparc-Syntax</a> &nbsp; [<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>