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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/Portability.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
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| -rw-r--r-- | share/doc/gccint/Portability.html | 122 |
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diff --git a/share/doc/gccint/Portability.html b/share/doc/gccint/Portability.html new file mode 100644 index 0000000..73ba742 --- /dev/null +++ b/share/doc/gccint/Portability.html @@ -0,0 +1,122 @@ +<!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: Portability</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Portability"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Portability"> +<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="index.html#Top" rel="up" title="Top"> +<link href="Interface.html#Interface" rel="next" title="Interface"> +<link href="Contributing.html#Contributing" rel="previous" title="Contributing"> +<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="Portability"></a> +<div class="header"> +<p> +Next: <a href="Interface.html#Interface" accesskey="n" rel="next">Interface</a>, Previous: <a href="Contributing.html#Contributing" accesskey="p" rel="previous">Contributing</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</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="GCC-and-Portability"></a> +<h2 class="chapter">2 GCC and Portability</h2> +<a name="index-portability"></a> +<a name="index-GCC-and-portability"></a> + +<p>GCC itself aims to be portable to any machine where <code>int</code> is at least +a 32-bit type. It aims to target machines with a flat (non-segmented) byte +addressed data address space (the code address space can be separate). +Target ABIs may have 8, 16, 32 or 64-bit <code>int</code> type. <code>char</code> +can be wider than 8 bits. +</p> +<p>GCC gets most of the information about the target machine from a machine +description which gives an algebraic formula for each of the machine’s +instructions. This is a very clean way to describe the target. But when +the compiler needs information that is difficult to express in this +fashion, ad-hoc parameters have been defined for machine descriptions. +The purpose of portability is to reduce the total work needed on the +compiler; it was not of interest for its own sake. +</p> +<a name="index-endianness"></a> +<a name="index-autoincrement-addressing_002c-availability"></a> +<a name="index-abort"></a> +<p>GCC does not contain machine dependent code, but it does contain code +that depends on machine parameters such as endianness (whether the most +significant byte has the highest or lowest address of the bytes in a word) +and the availability of autoincrement addressing. In the RTL-generation +pass, it is often necessary to have multiple strategies for generating code +for a particular kind of syntax tree, strategies that are usable for different +combinations of parameters. Often, not all possible cases have been +addressed, but only the common ones or only the ones that have been +encountered. As a result, a new target may require additional +strategies. You will know +if this happens because the compiler will call <code>abort</code>. Fortunately, +the new strategies can be added in a machine-independent fashion, and will +affect only the target machines that need them. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Interface.html#Interface" accesskey="n" rel="next">Interface</a>, Previous: <a href="Contributing.html#Contributing" accesskey="p" rel="previous">Contributing</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</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> |