You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
82 lines
3.9 KiB
HTML
82 lines
3.9 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>Object Attributes - Using as</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Using as">
|
|
<meta name="generator" content="makeinfo 4.13">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="prev" href="Pseudo-Ops.html#Pseudo-Ops" title="Pseudo Ops">
|
|
<link rel="next" href="Machine-Dependencies.html#Machine-Dependencies" title="Machine Dependencies">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
This file documents the GNU Assembler "as".
|
|
|
|
Copyright (C) 1991-2015 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 no Invariant Sections, with no Front-Cover Texts, and with no
|
|
Back-Cover Texts. A copy of the license is included in the
|
|
section entitled ``GNU Free Documentation License''.
|
|
|
|
-->
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<style type="text/css"><!--
|
|
pre.display { font-family:inherit }
|
|
pre.format { font-family:inherit }
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
|
pre.smallexample { font-size:smaller }
|
|
pre.smalllisp { font-size:smaller }
|
|
span.sc { font-variant:small-caps }
|
|
span.roman { font-family:serif; font-weight:normal; }
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<a name="Object-Attributes"></a>
|
|
<p>
|
|
Next: <a rel="next" accesskey="n" href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a>,
|
|
Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a>
|
|
<hr>
|
|
</div>
|
|
|
|
<h2 class="chapter">8 Object Attributes</h2>
|
|
|
|
<p><a name="index-object-attributes-520"></a>
|
|
<samp><span class="command">as</span></samp> assembles source files written for a specific architecture
|
|
into object files for that architecture. But not all object files are alike.
|
|
Many architectures support incompatible variations. For instance, floating
|
|
point arguments might be passed in floating point registers if the object file
|
|
requires hardware floating point support—or floating point arguments might be
|
|
passed in integer registers if the object file supports processors with no
|
|
hardware floating point unit. Or, if two objects are built for different
|
|
generations of the same architecture, the combination may require the
|
|
newer generation at run-time.
|
|
|
|
<p>This information is useful during and after linking. At link time,
|
|
<samp><span class="command">ld</span></samp> can warn about incompatible object files. After link
|
|
time, tools like <samp><span class="command">gdb</span></samp> can use it to process the linked file
|
|
correctly.
|
|
|
|
<p>Compatibility information is recorded as a series of object attributes. Each
|
|
attribute has a <dfn>vendor</dfn>, <dfn>tag</dfn>, and <dfn>value</dfn>. The vendor is a
|
|
string, and indicates who sets the meaning of the tag. The tag is an integer,
|
|
and indicates what property the attribute describes. The value may be a string
|
|
or an integer, and indicates how the property affects this object. Missing
|
|
attributes are the same as attributes with a zero value or empty string value.
|
|
|
|
<p>Object attributes were developed as part of the ABI for the ARM Architecture.
|
|
The file format is documented in <cite>ELF for the ARM Architecture</cite>.
|
|
|
|
<ul class="menu">
|
|
<li><a accesskey="1" href="GNU-Object-Attributes.html#GNU-Object-Attributes">GNU Object Attributes</a>: <span class="sc">gnu</span> Object Attributes
|
|
<li><a accesskey="2" href="Defining-New-Object-Attributes.html#Defining-New-Object-Attributes">Defining New Object Attributes</a>: Defining New Object Attributes
|
|
</ul>
|
|
|
|
</body></html>
|
|
|