176 lines
8.1 KiB
HTML
176 lines
8.1 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- Copyright (C) 1988-2016 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 5.2, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>GNU Compiler Collection (GCC) Internals: Storage References</title>
|
|
|
|
<meta name="description" content="GNU Compiler Collection (GCC) Internals: Storage References">
|
|
<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Storage References">
|
|
<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="Expression-trees.html#Expression-trees" rel="up" title="Expression trees">
|
|
<link href="Unary-and-Binary-Expressions.html#Unary-and-Binary-Expressions" rel="next" title="Unary and Binary Expressions">
|
|
<link href="Constant-expressions.html#Constant-expressions" rel="prev" title="Constant 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="Storage-References"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Unary-and-Binary-Expressions.html#Unary-and-Binary-Expressions" accesskey="n" rel="next">Unary and Binary Expressions</a>, Previous: <a href="Constant-expressions.html#Constant-expressions" accesskey="p" rel="prev">Constant expressions</a>, Up: <a href="Expression-trees.html#Expression-trees" accesskey="u" rel="up">Expression trees</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="References-to-storage"></a>
|
|
<h4 class="subsection">10.6.2 References to storage</h4>
|
|
<a name="index-ADDR_005fEXPR"></a>
|
|
<a name="index-INDIRECT_005fREF"></a>
|
|
<a name="index-MEM_005fREF"></a>
|
|
<a name="index-ARRAY_005fREF"></a>
|
|
<a name="index-ARRAY_005fRANGE_005fREF"></a>
|
|
<a name="index-TARGET_005fMEM_005fREF"></a>
|
|
<a name="index-COMPONENT_005fREF"></a>
|
|
|
|
<dl compact="compact">
|
|
<dt><code>ARRAY_REF</code></dt>
|
|
<dd><p>These nodes represent array accesses. The first operand is the array;
|
|
the second is the index. To calculate the address of the memory
|
|
accessed, you must scale the index by the size of the type of the array
|
|
elements. The type of these expressions must be the type of a component of
|
|
the array. The third and fourth operands are used after gimplification
|
|
to represent the lower bound and component size but should not be used
|
|
directly; call <code>array_ref_low_bound</code> and <code>array_ref_element_size</code>
|
|
instead.
|
|
</p>
|
|
</dd>
|
|
<dt><code>ARRAY_RANGE_REF</code></dt>
|
|
<dd><p>These nodes represent access to a range (or “slice”) of an array. The
|
|
operands are the same as that for <code>ARRAY_REF</code> and have the same
|
|
meanings. The type of these expressions must be an array whose component
|
|
type is the same as that of the first operand. The range of that array
|
|
type determines the amount of data these expressions access.
|
|
</p>
|
|
</dd>
|
|
<dt><code>TARGET_MEM_REF</code></dt>
|
|
<dd><p>These nodes represent memory accesses whose address directly map to
|
|
an addressing mode of the target architecture. The first argument
|
|
is <code>TMR_SYMBOL</code> and must be a <code>VAR_DECL</code> of an object with
|
|
a fixed address. The second argument is <code>TMR_BASE</code> and the
|
|
third one is <code>TMR_INDEX</code>. The fourth argument is
|
|
<code>TMR_STEP</code> and must be an <code>INTEGER_CST</code>. The fifth
|
|
argument is <code>TMR_OFFSET</code> and must be an <code>INTEGER_CST</code>.
|
|
Any of the arguments may be NULL if the appropriate component
|
|
does not appear in the address. Address of the <code>TARGET_MEM_REF</code>
|
|
is determined in the following way.
|
|
</p>
|
|
<div class="smallexample">
|
|
<pre class="smallexample">&TMR_SYMBOL + TMR_BASE + TMR_INDEX * TMR_STEP + TMR_OFFSET
|
|
</pre></div>
|
|
|
|
<p>The sixth argument is the reference to the original memory access, which
|
|
is preserved for the purposes of the RTL alias analysis. The seventh
|
|
argument is a tag representing the results of tree level alias analysis.
|
|
</p>
|
|
</dd>
|
|
<dt><code>ADDR_EXPR</code></dt>
|
|
<dd><p>These nodes are used to represent the address of an object. (These
|
|
expressions will always have pointer or reference type.) The operand may
|
|
be another expression, or it may be a declaration.
|
|
</p>
|
|
<p>As an extension, GCC allows users to take the address of a label. In
|
|
this case, the operand of the <code>ADDR_EXPR</code> will be a
|
|
<code>LABEL_DECL</code>. The type of such an expression is <code>void*</code>.
|
|
</p>
|
|
<p>If the object addressed is not an lvalue, a temporary is created, and
|
|
the address of the temporary is used.
|
|
</p>
|
|
</dd>
|
|
<dt><code>INDIRECT_REF</code></dt>
|
|
<dd><p>These nodes are used to represent the object pointed to by a pointer.
|
|
The operand is the pointer being dereferenced; it will always have
|
|
pointer or reference type.
|
|
</p>
|
|
</dd>
|
|
<dt><code>MEM_REF</code></dt>
|
|
<dd><p>These nodes are used to represent the object pointed to by a pointer
|
|
offset by a constant.
|
|
The first operand is the pointer being dereferenced; it will always have
|
|
pointer or reference type. The second operand is a pointer constant.
|
|
Its type is specifying the type to be used for type-based alias analysis.
|
|
</p>
|
|
</dd>
|
|
<dt><code>COMPONENT_REF</code></dt>
|
|
<dd><p>These nodes represent non-static data member accesses. The first
|
|
operand is the object (rather than a pointer to it); the second operand
|
|
is the <code>FIELD_DECL</code> for the data member. The third operand represents
|
|
the byte offset of the field, but should not be used directly; call
|
|
<code>component_ref_field_offset</code> instead.
|
|
</p>
|
|
|
|
</dd>
|
|
</dl>
|
|
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Unary-and-Binary-Expressions.html#Unary-and-Binary-Expressions" accesskey="n" rel="next">Unary and Binary Expressions</a>, Previous: <a href="Constant-expressions.html#Constant-expressions" accesskey="p" rel="prev">Constant expressions</a>, Up: <a href="Expression-trees.html#Expression-trees" accesskey="u" rel="up">Expression trees</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>
|