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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/Comparing-ordered-poly_005fints.html | |
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diff --git a/share/doc/gccint/Comparing-ordered-poly_005fints.html b/share/doc/gccint/Comparing-ordered-poly_005fints.html new file mode 100644 index 0000000..536f363 --- /dev/null +++ b/share/doc/gccint/Comparing-ordered-poly_005fints.html @@ -0,0 +1,146 @@ +<!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: Comparing ordered poly_ints</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Comparing ordered poly_ints"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Comparing ordered poly_ints"> +<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="Comparisons-involving-poly_005fint.html#Comparisons-involving-poly_005fint" rel="up" title="Comparisons involving poly_int"> +<link href="Checking-for-a-poly_005fint-marker-value.html#Checking-for-a-poly_005fint-marker-value" rel="next" title="Checking for a poly_int marker value"> +<link href="Comparing-potentially_002dunordered-poly_005fints.html#Comparing-potentially_002dunordered-poly_005fints" rel="previous" title="Comparing potentially-unordered poly_ints"> +<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="Comparing-ordered-poly_005fints"></a> +<div class="header"> +<p> +Next: <a href="Checking-for-a-poly_005fint-marker-value.html#Checking-for-a-poly_005fint-marker-value" accesskey="n" rel="next">Checking for a <code>poly_int</code> marker value</a>, Previous: <a href="Comparing-potentially_002dunordered-poly_005fints.html#Comparing-potentially_002dunordered-poly_005fints" accesskey="p" rel="previous">Comparing potentially-unordered <code>poly_int</code>s</a>, Up: <a href="Comparisons-involving-poly_005fint.html#Comparisons-involving-poly_005fint" accesskey="u" rel="up">Comparisons involving <code>poly_int</code></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="Comparing-ordered-poly_005fints-1"></a> +<h4 class="subsection">10.3.4 Comparing ordered <code>poly_int</code>s</h4> + +<p>In cases where there is a definite link between two <code>poly_int</code>s, +such as the outer and inner sizes of subregs, we usually require the sizes +to be ordered by the <code>known_le</code> partial order. <code>poly_int</code> provides +the following utility functions for ordered values: +</p> +<dl compact="compact"> +<dt>‘<samp>ordered_p (<var>a</var>, <var>b</var>)</samp>’</dt> +<dd><p>Return true if <var>a</var> and <var>b</var> are ordered by the <code>known_le</code> +partial order. +</p> +</dd> +<dt>‘<samp>ordered_min (<var>a</var>, <var>b</var>)</samp>’</dt> +<dd><p>Assert that <var>a</var> and <var>b</var> are ordered by <code>known_le</code> and return the +minimum of the two. When using this function, please add a comment explaining +why the values are known to be ordered. +</p> +</dd> +<dt>‘<samp>ordered_max (<var>a</var>, <var>b</var>)</samp>’</dt> +<dd><p>Assert that <var>a</var> and <var>b</var> are ordered by <code>known_le</code> and return the +maximum of the two. When using this function, please add a comment explaining +why the values are known to be ordered. +</p></dd> +</dl> + +<p>For example, if a subreg has an outer mode of size <var>outer</var> and an +inner mode of size <var>inner</var>: +</p> +<ul> +<li> the subreg is complete if known_eq (<var>inner</var>, <var>outer</var>) + +</li><li> otherwise, the subreg is paradoxical if known_le (<var>inner</var>, <var>outer</var>) + +</li><li> otherwise, the subreg is partial if known_le (<var>outer</var>, <var>inner</var>) + +</li><li> otherwise, the subreg is ill-formed +</li></ul> + +<p>Thus the subreg is only valid if +‘<samp>ordered_p (<var>outer</var>, <var>inner</var>)</samp>’ is true. If this condition +is already known to be true then: +</p> +<ul> +<li> the subreg is complete if known_eq (<var>inner</var>, <var>outer</var>) + +</li><li> the subreg is paradoxical if maybe_lt (<var>inner</var>, <var>outer</var>) + +</li><li> the subreg is partial if maybe_lt (<var>outer</var>, <var>inner</var>) +</li></ul> + +<p>with the three conditions being mutually exclusive. +</p> +<p>Code that checks whether a subreg is valid would therefore generally +check whether <code>ordered_p</code> holds (in addition to whatever other +checks are required for subreg validity). Code that is dealing +with existing subregs can assert that <code>ordered_p</code> holds +and use either of the classifications above. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Checking-for-a-poly_005fint-marker-value.html#Checking-for-a-poly_005fint-marker-value" accesskey="n" rel="next">Checking for a <code>poly_int</code> marker value</a>, Previous: <a href="Comparing-potentially_002dunordered-poly_005fints.html#Comparing-potentially_002dunordered-poly_005fints" accesskey="p" rel="previous">Comparing potentially-unordered <code>poly_int</code>s</a>, Up: <a href="Comparisons-involving-poly_005fint.html#Comparisons-involving-poly_005fint" accesskey="u" rel="up">Comparisons involving <code>poly_int</code></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> |