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diff --git a/share/doc/gccint/Compound-Lvalues.html b/share/doc/gccint/Compound-Lvalues.html new file mode 100644 index 0000000..0841232 --- /dev/null +++ b/share/doc/gccint/Compound-Lvalues.html @@ -0,0 +1,101 @@ +<!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: Compound Lvalues</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Compound Lvalues"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Compound Lvalues"> +<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="Operands.html#Operands" rel="up" title="Operands"> +<link href="Conditional-Expressions.html#Conditional-Expressions" rel="next" title="Conditional Expressions"> +<link href="Compound-Expressions.html#Compound-Expressions" rel="previous" title="Compound Expressions"> +<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="Compound-Lvalues"></a> +<div class="header"> +<p> +Next: <a href="Conditional-Expressions.html#Conditional-Expressions" accesskey="n" rel="next">Conditional Expressions</a>, Previous: <a href="Compound-Expressions.html#Compound-Expressions" accesskey="p" rel="previous">Compound Expressions</a>, Up: <a href="Operands.html#Operands" accesskey="u" rel="up">Operands</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="Compound-Lvalues-1"></a> +<h4 class="subsection">12.6.2 Compound Lvalues</h4> +<a name="index-Compound-Lvalues"></a> + +<p>Currently compound lvalues involving array and structure field references +are not broken down; an expression like <code>a.b[2] = 42</code> is not reduced +any further (though complex array subscripts are). This restriction is a +workaround for limitations in later optimizers; if we were to convert this +to +</p> +<div class="smallexample"> +<pre class="smallexample">T1 = &a.b; +T1[2] = 42; +</pre></div> + +<p>alias analysis would not remember that the reference to <code>T1[2]</code> came +by way of <code>a.b</code>, so it would think that the assignment could alias +another member of <code>a</code>; this broke <code>struct-alias-1.c</code>. Future +optimizer improvements may make this limitation unnecessary. +</p> + + + +</body> +</html> |