105 lines
4.3 KiB
HTML
105 lines
4.3 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2016 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>GNU Compiler Collection (GCC) Internals: Reading RTL</title>
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<meta name="description" content="GNU Compiler Collection (GCC) Internals: Reading RTL">
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<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Reading RTL">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="RTL.html#RTL" rel="up" title="RTL">
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<link href="Control-Flow.html#Control-Flow" rel="next" title="Control Flow">
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<link href="Sharing.html#Sharing" rel="prev" title="Sharing">
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<style type="text/css">
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<!--
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Reading-RTL"></a>
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<div class="header">
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<p>
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Previous: <a href="Sharing.html#Sharing" accesskey="p" rel="prev">Sharing</a>, Up: <a href="RTL.html#RTL" accesskey="u" rel="up">RTL</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>
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</div>
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<hr>
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<a name="Reading-RTL-1"></a>
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<h3 class="section">13.22 Reading RTL</h3>
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<p>To read an RTL object from a file, call <code>read_rtx</code>. It takes one
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argument, a stdio stream, and returns a single RTL object. This routine
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is defined in <samp>read-rtl.c</samp>. It is not available in the compiler
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itself, only the various programs that generate the compiler back end
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from the machine description.
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</p>
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<p>People frequently have the idea of using RTL stored as text in a file as
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an interface between a language front end and the bulk of GCC. This
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idea is not feasible.
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</p>
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<p>GCC was designed to use RTL internally only. Correct RTL for a given
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program is very dependent on the particular target machine. And the RTL
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does not contain all the information about the program.
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</p>
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<p>The proper way to interface GCC to a new language front end is with
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the “tree” data structure, described in the files <samp>tree.h</samp> and
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<samp>tree.def</samp>. The documentation for this structure (see <a href="GENERIC.html#GENERIC">GENERIC</a>)
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is incomplete.
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</p>
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</body>
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</html>
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