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diff --git a/share/doc/gccint/Substitutions.html b/share/doc/gccint/Substitutions.html new file mode 100644 index 0000000..3b9c1f3 --- /dev/null +++ b/share/doc/gccint/Substitutions.html @@ -0,0 +1,150 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 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 the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>GNU Compiler Collection (GCC) Internals: Substitutions</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Substitutions"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Substitutions"> +<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="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Mode-Iterators.html#Mode-Iterators" rel="up" title="Mode Iterators"> +<link href="Examples.html#Examples" rel="next" title="Examples"> +<link href="Defining-Mode-Iterators.html#Defining-Mode-Iterators" rel="previous" title="Defining Mode Iterators"> +<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="Substitutions"></a> +<div class="header"> +<p> +Next: <a href="Examples.html#Examples" accesskey="n" rel="next">Examples</a>, Previous: <a href="Defining-Mode-Iterators.html#Defining-Mode-Iterators" accesskey="p" rel="previous">Defining Mode Iterators</a>, Up: <a href="Mode-Iterators.html#Mode-Iterators" accesskey="u" rel="up">Mode Iterators</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Substitution-in-Mode-Iterators"></a> +<h4 class="subsubsection">17.23.1.2 Substitution in Mode Iterators</h4> +<a name="index-define_005fmode_005fattr"></a> + +<p>If an <samp>.md</samp> file construct uses mode iterators, each version of the +construct will often need slightly different strings or modes. For +example: +</p> +<ul> +<li> When a <code>define_expand</code> defines several <code>add<var>m</var>3</code> patterns +(see <a href="Standard-Names.html#Standard-Names">Standard Names</a>), each expander will need to use the +appropriate mode name for <var>m</var>. + +</li><li> When a <code>define_insn</code> defines several instruction patterns, +each instruction will often use a different assembler mnemonic. + +</li><li> When a <code>define_insn</code> requires operands with different modes, +using an iterator for one of the operand modes usually requires a specific +mode for the other operand(s). +</li></ul> + +<p>GCC supports such variations through a system of “mode attributes”. +There are two standard attributes: <code>mode</code>, which is the name of +the mode in lower case, and <code>MODE</code>, which is the same thing in +upper case. You can define other attributes using: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_mode_attr <var>name</var> [(<var>mode1</var> "<var>value1</var>") … (<var>moden</var> "<var>valuen</var>")]) +</pre></div> + +<p>where <var>name</var> is the name of the attribute and <var>valuei</var> +is the value associated with <var>modei</var>. +</p> +<p>When GCC replaces some <var>:iterator</var> with <var>:mode</var>, it will scan +each string and mode in the pattern for sequences of the form +<code><<var>iterator</var>:<var>attr</var>></code>, where <var>attr</var> is the name of a +mode attribute. If the attribute is defined for <var>mode</var>, the whole +<code><…></code> sequence will be replaced by the appropriate attribute +value. +</p> +<p>For example, suppose an <samp>.md</samp> file has: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_mode_iterator P [(SI "Pmode == SImode") (DI "Pmode == DImode")]) +(define_mode_attr load [(SI "lw") (DI "ld")]) +</pre></div> + +<p>If one of the patterns that uses <code>:P</code> contains the string +<code>"<P:load>\t%0,%1"</code>, the <code>SI</code> version of that pattern +will use <code>"lw\t%0,%1"</code> and the <code>DI</code> version will use +<code>"ld\t%0,%1"</code>. +</p> +<p>Here is an example of using an attribute for a mode: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_mode_iterator LONG [SI DI]) +(define_mode_attr SHORT [(SI "HI") (DI "SI")]) +(define_insn … + (sign_extend:LONG (match_operand:<LONG:SHORT> …)) …) +</pre></div> + +<p>The <code><var>iterator</var>:</code> prefix may be omitted, in which case the +substitution will be attempted for every iterator expansion. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Examples.html#Examples" accesskey="n" rel="next">Examples</a>, Previous: <a href="Defining-Mode-Iterators.html#Defining-Mode-Iterators" accesskey="p" rel="previous">Defining Mode Iterators</a>, Up: <a href="Mode-Iterators.html#Mode-Iterators" accesskey="u" rel="up">Mode Iterators</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |