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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gccint/Define-Subst.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
Diffstat (limited to 'share/doc/gccint/Define-Subst.html')
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diff --git a/share/doc/gccint/Define-Subst.html b/share/doc/gccint/Define-Subst.html new file mode 100644 index 0000000..5ad0fc4 --- /dev/null +++ b/share/doc/gccint/Define-Subst.html @@ -0,0 +1,140 @@ +<!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: Define Subst</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Define Subst"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Define Subst"> +<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="Machine-Desc.html#Machine-Desc" rel="up" title="Machine Desc"> +<link href="Define-Subst-Example.html#Define-Subst-Example" rel="next" title="Define Subst Example"> +<link href="Conditional-Execution.html#Conditional-Execution" rel="previous" title="Conditional Execution"> +<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="Define-Subst"></a> +<div class="header"> +<p> +Next: <a href="Constant-Definitions.html#Constant-Definitions" accesskey="n" rel="next">Constant Definitions</a>, Previous: <a href="Conditional-Execution.html#Conditional-Execution" accesskey="p" rel="previous">Conditional Execution</a>, Up: <a href="Machine-Desc.html#Machine-Desc" accesskey="u" rel="up">Machine Desc</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="RTL-Templates-Transformations"></a> +<h3 class="section">17.21 RTL Templates Transformations</h3> +<a name="index-define_005fsubst"></a> + +<p>For some hardware architectures there are common cases when the RTL +templates for the instructions can be derived from the other RTL +templates using simple transformations. E.g., <samp>i386.md</samp> contains +an RTL template for the ordinary <code>sub</code> instruction— +<code>*subsi_1</code>, and for the <code>sub</code> instruction with subsequent +zero-extension—<code>*subsi_1_zext</code>. Such cases can be easily +implemented by a single meta-template capable of generating a modified +case based on the initial one: +</p> +<a name="index-define_005fsubst-4"></a> +<div class="smallexample"> +<pre class="smallexample">(define_subst "<var>name</var>" + [<var>input-template</var>] + "<var>condition</var>" + [<var>output-template</var>]) +</pre></div> +<p><var>input-template</var> is a pattern describing the source RTL template, +which will be transformed. +</p> +<p><var>condition</var> is a C expression that is conjunct with the condition +from the input-template to generate a condition to be used in the +output-template. +</p> +<p><var>output-template</var> is a pattern that will be used in the resulting +template. +</p> +<p><code>define_subst</code> mechanism is tightly coupled with the notion of the +subst attribute (see <a href="Subst-Iterators.html#Subst-Iterators">Subst Iterators</a>). The use of +<code>define_subst</code> is triggered by a reference to a subst attribute in +the transforming RTL template. This reference initiates duplication of +the source RTL template and substitution of the attributes with their +values. The source RTL template is left unchanged, while the copy is +transformed by <code>define_subst</code>. This transformation can fail in the +case when the source RTL template is not matched against the +input-template of the <code>define_subst</code>. In such case the copy is +deleted. +</p> +<p><code>define_subst</code> can be used only in <code>define_insn</code> and +<code>define_expand</code>, it cannot be used in other expressions (e.g. in +<code>define_insn_and_split</code>). +</p> +<table class="menu" border="0" cellspacing="0"> +<tr><td align="left" valign="top">• <a href="Define-Subst-Example.html#Define-Subst-Example" accesskey="1">Define Subst Example</a>:</td><td> </td><td align="left" valign="top">Example of <code>define_subst</code> work. +</td></tr> +<tr><td align="left" valign="top">• <a href="Define-Subst-Pattern-Matching.html#Define-Subst-Pattern-Matching" accesskey="2">Define Subst Pattern Matching</a>:</td><td> </td><td align="left" valign="top">Process of template comparison. +</td></tr> +<tr><td align="left" valign="top">• <a href="Define-Subst-Output-Template.html#Define-Subst-Output-Template" accesskey="3">Define Subst Output Template</a>:</td><td> </td><td align="left" valign="top">Generation of output template. +</td></tr> +</table> + +<hr> +<div class="header"> +<p> +Next: <a href="Constant-Definitions.html#Constant-Definitions" accesskey="n" rel="next">Constant Definitions</a>, Previous: <a href="Conditional-Execution.html#Conditional-Execution" accesskey="p" rel="previous">Conditional Execution</a>, Up: <a href="Machine-Desc.html#Machine-Desc" accesskey="u" rel="up">Machine Desc</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> |