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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/Code-Iterators.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
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diff --git a/share/doc/gccint/Code-Iterators.html b/share/doc/gccint/Code-Iterators.html new file mode 100644 index 0000000..6af8442 --- /dev/null +++ b/share/doc/gccint/Code-Iterators.html @@ -0,0 +1,188 @@ +<!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: Code Iterators</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Code Iterators"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Code Iterators"> +<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="Iterators.html#Iterators" rel="up" title="Iterators"> +<link href="Int-Iterators.html#Int-Iterators" rel="next" title="Int Iterators"> +<link href="Examples.html#Examples" rel="previous" title="Examples"> +<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="Code-Iterators"></a> +<div class="header"> +<p> +Next: <a href="Int-Iterators.html#Int-Iterators" accesskey="n" rel="next">Int Iterators</a>, Previous: <a href="Mode-Iterators.html#Mode-Iterators" accesskey="p" rel="previous">Mode Iterators</a>, Up: <a href="Iterators.html#Iterators" accesskey="u" rel="up">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="Code-Iterators-1"></a> +<h4 class="subsection">17.23.2 Code Iterators</h4> +<a name="index-code-iterators-in-_002emd-files"></a> +<a name="index-define_005fcode_005fiterator"></a> +<a name="index-define_005fcode_005fattr"></a> + +<p>Code iterators operate in a similar way to mode iterators. See <a href="Mode-Iterators.html#Mode-Iterators">Mode Iterators</a>. +</p> +<p>The construct: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_code_iterator <var>name</var> [(<var>code1</var> "<var>cond1</var>") … (<var>coden</var> "<var>condn</var>")]) +</pre></div> + +<p>defines a pseudo rtx code <var>name</var> that can be instantiated as +<var>codei</var> if condition <var>condi</var> is true. Each <var>codei</var> +must have the same rtx format. See <a href="RTL-Classes.html#RTL-Classes">RTL Classes</a>. +</p> +<p>As with mode iterators, each pattern that uses <var>name</var> will be +expanded <var>n</var> times, once with all uses of <var>name</var> replaced by +<var>code1</var>, once with all uses replaced by <var>code2</var>, and so on. +See <a href="Defining-Mode-Iterators.html#Defining-Mode-Iterators">Defining Mode Iterators</a>. +</p> +<p>It is possible to define attributes for codes as well as for modes. +There are two standard code attributes: <code>code</code>, the name of the +code in lower case, and <code>CODE</code>, the name of the code in upper case. +Other attributes are defined using: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_code_attr <var>name</var> [(<var>code1</var> "<var>value1</var>") … (<var>coden</var> "<var>valuen</var>")]) +</pre></div> + +<p>Instruction patterns can use code attributes as rtx codes, which can be +useful if two sets of codes act in tandem. For example, the following +<code>define_insn</code> defines two patterns, one calculating a signed absolute +difference and another calculating an unsigned absolute difference: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_code_iterator any_max [smax umax]) +(define_code_attr paired_min [(smax "smin") (umax "umin")]) +(define_insn … + [(set (match_operand:SI 0 …) + (minus:SI (any_max:SI (match_operand:SI 1 …) + (match_operand:SI 2 …)) + (<paired_min>:SI (match_dup 1) (match_dup 2))))] + …) +</pre></div> + +<p>The signed version of the instruction uses <code>smax</code> and <code>smin</code> +while the unsigned version uses <code>umax</code> and <code>umin</code>. There +are no versions that pair <code>smax</code> with <code>umin</code> or <code>umax</code> +with <code>smin</code>. +</p> +<p>Here’s an example of code iterators in action, taken from the MIPS port: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_code_iterator any_cond [unordered ordered unlt unge uneq ltgt unle ungt + eq ne gt ge lt le gtu geu ltu leu]) + +(define_expand "b<code>" + [(set (pc) + (if_then_else (any_cond:CC (cc0) + (const_int 0)) + (label_ref (match_operand 0 "")) + (pc)))] + "" +{ + gen_conditional_branch (operands, <CODE>); + DONE; +}) +</pre></div> + +<p>This is equivalent to: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_expand "bunordered" + [(set (pc) + (if_then_else (unordered:CC (cc0) + (const_int 0)) + (label_ref (match_operand 0 "")) + (pc)))] + "" +{ + gen_conditional_branch (operands, UNORDERED); + DONE; +}) + +(define_expand "bordered" + [(set (pc) + (if_then_else (ordered:CC (cc0) + (const_int 0)) + (label_ref (match_operand 0 "")) + (pc)))] + "" +{ + gen_conditional_branch (operands, ORDERED); + DONE; +}) + +… +</pre></div> + +<hr> +<div class="header"> +<p> +Next: <a href="Int-Iterators.html#Int-Iterators" accesskey="n" rel="next">Int Iterators</a>, Previous: <a href="Mode-Iterators.html#Mode-Iterators" accesskey="p" rel="previous">Mode Iterators</a>, Up: <a href="Iterators.html#Iterators" accesskey="u" rel="up">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> |