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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/RTL-Objects.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
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diff --git a/share/doc/gccint/RTL-Objects.html b/share/doc/gccint/RTL-Objects.html new file mode 100644 index 0000000..c0077f3 --- /dev/null +++ b/share/doc/gccint/RTL-Objects.html @@ -0,0 +1,170 @@ +<!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: RTL Objects</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: RTL Objects"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: RTL Objects"> +<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="RTL.html#RTL" rel="up" title="RTL"> +<link href="RTL-Classes.html#RTL-Classes" rel="next" title="RTL Classes"> +<link href="RTL.html#RTL" rel="previous" title="RTL"> +<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="RTL-Objects"></a> +<div class="header"> +<p> +Next: <a href="RTL-Classes.html#RTL-Classes" accesskey="n" rel="next">RTL Classes</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> +</div> +<hr> +<a name="RTL-Object-Types"></a> +<h3 class="section">14.1 RTL Object Types</h3> +<a name="index-RTL-object-types"></a> + +<a name="index-RTL-integers"></a> +<a name="index-RTL-strings"></a> +<a name="index-RTL-vectors"></a> +<a name="index-RTL-expression"></a> +<a name="index-RTX-_0028See-RTL_0029"></a> +<p>RTL uses five kinds of objects: expressions, integers, wide integers, +strings and vectors. Expressions are the most important ones. An RTL +expression (“RTX”, for short) is a C structure, but it is usually +referred to with a pointer; a type that is given the typedef name +<code>rtx</code>. +</p> +<p>An integer is simply an <code>int</code>; their written form uses decimal +digits. A wide integer is an integral object whose type is +<code>HOST_WIDE_INT</code>; their written form uses decimal digits. +</p> +<p>A string is a sequence of characters. In core it is represented as a +<code>char *</code> in usual C fashion, and it is written in C syntax as well. +However, strings in RTL may never be null. If you write an empty string in +a machine description, it is represented in core as a null pointer rather +than as a pointer to a null character. In certain contexts, these null +pointers instead of strings are valid. Within RTL code, strings are most +commonly found inside <code>symbol_ref</code> expressions, but they appear in +other contexts in the RTL expressions that make up machine descriptions. +</p> +<p>In a machine description, strings are normally written with double +quotes, as you would in C. However, strings in machine descriptions may +extend over many lines, which is invalid C, and adjacent string +constants are not concatenated as they are in C. Any string constant +may be surrounded with a single set of parentheses. Sometimes this +makes the machine description easier to read. +</p> +<p>There is also a special syntax for strings, which can be useful when C +code is embedded in a machine description. Wherever a string can +appear, it is also valid to write a C-style brace block. The entire +brace block, including the outermost pair of braces, is considered to be +the string constant. Double quote characters inside the braces are not +special. Therefore, if you write string constants in the C code, you +need not escape each quote character with a backslash. +</p> +<p>A vector contains an arbitrary number of pointers to expressions. The +number of elements in the vector is explicitly present in the vector. +The written form of a vector consists of square brackets +(‘<samp>[…]</samp>’) surrounding the elements, in sequence and with +whitespace separating them. Vectors of length zero are not created; +null pointers are used instead. +</p> +<a name="index-expression-codes"></a> +<a name="index-codes_002c-RTL-expression"></a> +<a name="index-GET_005fCODE"></a> +<a name="index-PUT_005fCODE"></a> +<p>Expressions are classified by <em>expression codes</em> (also called RTX +codes). The expression code is a name defined in <samp>rtl.def</samp>, which is +also (in uppercase) a C enumeration constant. The possible expression +codes and their meanings are machine-independent. The code of an RTX can +be extracted with the macro <code>GET_CODE (<var>x</var>)</code> and altered with +<code>PUT_CODE (<var>x</var>, <var>newcode</var>)</code>. +</p> +<p>The expression code determines how many operands the expression contains, +and what kinds of objects they are. In RTL, unlike Lisp, you cannot tell +by looking at an operand what kind of object it is. Instead, you must know +from its context—from the expression code of the containing expression. +For example, in an expression of code <code>subreg</code>, the first operand is +to be regarded as an expression and the second operand as a polynomial +integer. In an expression of code <code>plus</code>, there are two operands, +both of which are to be regarded as expressions. In a <code>symbol_ref</code> +expression, there is one operand, which is to be regarded as a string. +</p> +<p>Expressions are written as parentheses containing the name of the +expression type, its flags and machine mode if any, and then the operands +of the expression (separated by spaces). +</p> +<p>Expression code names in the ‘<samp>md</samp>’ file are written in lowercase, +but when they appear in C code they are written in uppercase. In this +manual, they are shown as follows: <code>const_int</code>. +</p> +<a name="index-_0028nil_0029"></a> +<a name="index-nil"></a> +<p>In a few contexts a null pointer is valid where an expression is normally +wanted. The written form of this is <code>(nil)</code>. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="RTL-Classes.html#RTL-Classes" accesskey="n" rel="next">RTL Classes</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> +</div> + + + +</body> +</html> |