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.
95 lines
4.3 KiB
HTML
95 lines
4.3 KiB
HTML
4 years ago
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html>
|
||
|
|
<!-- This manual describes how to install and use the GNU multiple precision
|
||
|
|
arithmetic library, version 6.1.0.
|
||
|
|
|
||
|
|
Copyright 1991, 1993-2015 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 the Front-Cover Texts being "A GNU Manual", and with the Back-Cover
|
||
|
|
Texts being "You have freedom to copy and modify this GNU Manual, like GNU
|
||
|
|
software". A copy of the license is included in
|
||
|
|
GNU Free Documentation License. -->
|
||
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<title>Assembly Software Pipelining (GNU MP 6.1.0)</title>
|
||
|
|
|
||
|
|
<meta name="description" content="How to install and use the GNU multiple precision arithmetic library, version 6.1.0.">
|
||
|
|
<meta name="keywords" content="Assembly Software Pipelining (GNU MP 6.1.0)">
|
||
|
|
<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=iso-8859-1">
|
||
|
|
<link href="index.html#Top" rel="start" title="Top">
|
||
|
|
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
||
|
|
<link href="Assembly-Coding.html#Assembly-Coding" rel="up" title="Assembly Coding">
|
||
|
|
<link href="Assembly-Loop-Unrolling.html#Assembly-Loop-Unrolling" rel="next" title="Assembly Loop Unrolling">
|
||
|
|
<link href="Assembly-SIMD-Instructions.html#Assembly-SIMD-Instructions" rel="prev" title="Assembly SIMD Instructions">
|
||
|
|
<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="Assembly-Software-Pipelining"></a>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Assembly-Loop-Unrolling.html#Assembly-Loop-Unrolling" accesskey="n" rel="next">Assembly Loop Unrolling</a>, Previous: <a href="Assembly-SIMD-Instructions.html#Assembly-SIMD-Instructions" accesskey="p" rel="prev">Assembly SIMD Instructions</a>, Up: <a href="Assembly-Coding.html#Assembly-Coding" accesskey="u" rel="up">Assembly Coding</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<a name="Software-Pipelining"></a>
|
||
|
|
<h4 class="subsection">15.8.8 Software Pipelining</h4>
|
||
|
|
<a name="index-Assembly-software-pipelining"></a>
|
||
|
|
|
||
|
|
<p>Software pipelining consists of scheduling instructions around the branch
|
||
|
|
point in a loop. For example a loop might issue a load not for use in the
|
||
|
|
present iteration but the next, thereby allowing extra cycles for the data to
|
||
|
|
arrive from memory.
|
||
|
|
</p>
|
||
|
|
<p>Naturally this is wanted only when doing things like loads or multiplies that
|
||
|
|
take several cycles to complete, and only where a CPU has multiple functional
|
||
|
|
units so that other work can be done in the meantime.
|
||
|
|
</p>
|
||
|
|
<p>A pipeline with several stages will have a data value in progress at each
|
||
|
|
stage and each loop iteration moves them along one stage. This is like
|
||
|
|
juggling.
|
||
|
|
</p>
|
||
|
|
<p>If the latency of some instruction is greater than the loop time then it will
|
||
|
|
be necessary to unroll, so one register has a result ready to use while
|
||
|
|
another (or multiple others) are still in progress. (see <a href="Assembly-Loop-Unrolling.html#Assembly-Loop-Unrolling">Assembly Loop Unrolling</a>).
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|