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diff --git a/share/doc/gccint/Conversions.html b/share/doc/gccint/Conversions.html new file mode 100644 index 0000000..5976474 --- /dev/null +++ b/share/doc/gccint/Conversions.html @@ -0,0 +1,235 @@ +<!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: Conversions</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Conversions"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Conversions"> +<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-Declarations.html#RTL-Declarations" rel="next" title="RTL Declarations"> +<link href="Vector-Operations.html#Vector-Operations" rel="previous" title="Vector Operations"> +<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="Conversions"></a> +<div class="header"> +<p> +Next: <a href="RTL-Declarations.html#RTL-Declarations" accesskey="n" rel="next">RTL Declarations</a>, Previous: <a href="Vector-Operations.html#Vector-Operations" accesskey="p" rel="previous">Vector Operations</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="Conversions-1"></a> +<h3 class="section">14.13 Conversions</h3> +<a name="index-conversions"></a> +<a name="index-machine-mode-conversions"></a> + +<p>All conversions between machine modes must be represented by +explicit conversion operations. For example, an expression +which is the sum of a byte and a full word cannot be written as +<code>(plus:SI (reg:QI 34) (reg:SI 80))</code> because the <code>plus</code> +operation requires two operands of the same machine mode. +Therefore, the byte-sized operand is enclosed in a conversion +operation, as in +</p> +<div class="smallexample"> +<pre class="smallexample">(plus:SI (sign_extend:SI (reg:QI 34)) (reg:SI 80)) +</pre></div> + +<p>The conversion operation is not a mere placeholder, because there +may be more than one way of converting from a given starting mode +to the desired final mode. The conversion operation code says how +to do it. +</p> +<p>For all conversion operations, <var>x</var> must not be <code>VOIDmode</code> +because the mode in which to do the conversion would not be known. +The conversion must either be done at compile-time or <var>x</var> +must be placed into a register. +</p> +<dl compact="compact"> +<dd><a name="index-sign_005fextend"></a> +</dd> +<dt><code>(sign_extend:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of sign-extending the value <var>x</var> +to machine mode <var>m</var>. <var>m</var> must be a fixed-point mode +and <var>x</var> a fixed-point value of a mode narrower than <var>m</var>. +</p> +<a name="index-zero_005fextend"></a> +</dd> +<dt><code>(zero_extend:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of zero-extending the value <var>x</var> +to machine mode <var>m</var>. <var>m</var> must be a fixed-point mode +and <var>x</var> a fixed-point value of a mode narrower than <var>m</var>. +</p> +<a name="index-float_005fextend"></a> +</dd> +<dt><code>(float_extend:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of extending the value <var>x</var> +to machine mode <var>m</var>. <var>m</var> must be a floating point mode +and <var>x</var> a floating point value of a mode narrower than <var>m</var>. +</p> +<a name="index-truncate"></a> +</dd> +<dt><code>(truncate:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of truncating the value <var>x</var> +to machine mode <var>m</var>. <var>m</var> must be a fixed-point mode +and <var>x</var> a fixed-point value of a mode wider than <var>m</var>. +</p> +<a name="index-ss_005ftruncate"></a> +</dd> +<dt><code>(ss_truncate:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of truncating the value <var>x</var> +to machine mode <var>m</var>, using signed saturation in the case of +overflow. Both <var>m</var> and the mode of <var>x</var> must be fixed-point +modes. +</p> +<a name="index-us_005ftruncate"></a> +</dd> +<dt><code>(us_truncate:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of truncating the value <var>x</var> +to machine mode <var>m</var>, using unsigned saturation in the case of +overflow. Both <var>m</var> and the mode of <var>x</var> must be fixed-point +modes. +</p> +<a name="index-float_005ftruncate"></a> +</dd> +<dt><code>(float_truncate:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of truncating the value <var>x</var> +to machine mode <var>m</var>. <var>m</var> must be a floating point mode +and <var>x</var> a floating point value of a mode wider than <var>m</var>. +</p> +<a name="index-float"></a> +</dd> +<dt><code>(float:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of converting fixed point value <var>x</var>, +regarded as signed, to floating point mode <var>m</var>. +</p> +<a name="index-unsigned_005ffloat"></a> +</dd> +<dt><code>(unsigned_float:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of converting fixed point value <var>x</var>, +regarded as unsigned, to floating point mode <var>m</var>. +</p> +<a name="index-fix"></a> +</dd> +<dt><code>(fix:<var>m</var> <var>x</var>)</code></dt> +<dd><p>When <var>m</var> is a floating-point mode, represents the result of +converting floating point value <var>x</var> (valid for mode <var>m</var>) to an +integer, still represented in floating point mode <var>m</var>, by rounding +towards zero. +</p> +<p>When <var>m</var> is a fixed-point mode, represents the result of +converting floating point value <var>x</var> to mode <var>m</var>, regarded as +signed. How rounding is done is not specified, so this operation may +be used validly in compiling C code only for integer-valued operands. +</p> +<a name="index-unsigned_005ffix"></a> +</dd> +<dt><code>(unsigned_fix:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of converting floating point value <var>x</var> to +fixed point mode <var>m</var>, regarded as unsigned. How rounding is done +is not specified. +</p> +<a name="index-fract_005fconvert"></a> +</dd> +<dt><code>(fract_convert:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of converting fixed-point value <var>x</var> to +fixed-point mode <var>m</var>, signed integer value <var>x</var> to +fixed-point mode <var>m</var>, floating-point value <var>x</var> to +fixed-point mode <var>m</var>, fixed-point value <var>x</var> to integer mode <var>m</var> +regarded as signed, or fixed-point value <var>x</var> to floating-point mode <var>m</var>. +When overflows or underflows happen, the results are undefined. +</p> +<a name="index-sat_005ffract"></a> +</dd> +<dt><code>(sat_fract:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of converting fixed-point value <var>x</var> to +fixed-point mode <var>m</var>, signed integer value <var>x</var> to +fixed-point mode <var>m</var>, or floating-point value <var>x</var> to +fixed-point mode <var>m</var>. +When overflows or underflows happen, the results are saturated to the +maximum or the minimum. +</p> +<a name="index-unsigned_005ffract_005fconvert"></a> +</dd> +<dt><code>(unsigned_fract_convert:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of converting fixed-point value <var>x</var> to +integer mode <var>m</var> regarded as unsigned, or unsigned integer value <var>x</var> to +fixed-point mode <var>m</var>. +When overflows or underflows happen, the results are undefined. +</p> +<a name="index-unsigned_005fsat_005ffract"></a> +</dd> +<dt><code>(unsigned_sat_fract:<var>m</var> <var>x</var>)</code></dt> +<dd><p>Represents the result of converting unsigned integer value <var>x</var> to +fixed-point mode <var>m</var>. +When overflows or underflows happen, the results are saturated to the +maximum or the minimum. +</p></dd> +</dl> + +<hr> +<div class="header"> +<p> +Next: <a href="RTL-Declarations.html#RTL-Declarations" accesskey="n" rel="next">RTL Declarations</a>, Previous: <a href="Vector-Operations.html#Vector-Operations" accesskey="p" rel="previous">Vector Operations</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> |