| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- Copyright (C) 1992-2015 Free Software Foundation, Inc. |
| Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon, |
| and David MacKenzie. |
| |
| 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". --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>STABS: Global Variables</title> |
| |
| <meta name="description" content="STABS: Global Variables"> |
| <meta name="keywords" content="STABS: Global Variables"> |
| <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="Symbol-Types-Index.html#Symbol-Types-Index" rel="index" title="Symbol Types Index"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="Variables.html#Variables" rel="up" title="Variables"> |
| <link href="Register-Variables.html#Register-Variables" rel="next" title="Register Variables"> |
| <link href="Stack-Variables.html#Stack-Variables" rel="prev" title="Stack Variables"> |
| <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="Global-Variables"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Register-Variables.html#Register-Variables" accesskey="n" rel="next">Register Variables</a>, Previous: <a href="Stack-Variables.html#Stack-Variables" accesskey="p" rel="prev">Stack Variables</a>, Up: <a href="Variables.html#Variables" accesskey="u" rel="up">Variables</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <hr> |
| <a name="Global-Variables-1"></a> |
| <h3 class="section">4.2 Global Variables</h3> |
| |
| <a name="index-N_005fGSYM"></a> |
| <a name="index-C_005fGSYM"></a> |
| <p>A variable whose scope is not specific to just one source file is |
| represented by the ‘<samp>G</samp>’ symbol descriptor. These stabs use the |
| <code>N_GSYM</code> stab type (C_GSYM for XCOFF). The type information for |
| the stab (see <a href="String-Field.html#String-Field">String Field</a>) gives the type of the variable. |
| </p> |
| <p>For example, the following source code: |
| </p> |
| <div class="example"> |
| <pre class="example">char g_foo = 'c'; |
| </pre></div> |
| |
| <p>yields the following assembly code: |
| </p> |
| <div class="example"> |
| <pre class="example">.stabs "g_foo:G2",32,0,0,0 # <span class="roman">32 is N_GSYM</span> |
| .global _g_foo |
| .data |
| _g_foo: |
| .byte 99 |
| </pre></div> |
| |
| <p>The address of the variable represented by the <code>N_GSYM</code> is not |
| contained in the <code>N_GSYM</code> stab. The debugger gets this information |
| from the external symbol for the global variable. In the example above, |
| the <code>.global _g_foo</code> and <code>_g_foo:</code> lines tell the assembler to |
| produce an external symbol. |
| </p> |
| <p>Some compilers, like GCC, output <code>N_GSYM</code> stabs only once, where |
| the variable is defined. Other compilers, like SunOS4 /bin/cc, output a |
| <code>N_GSYM</code> stab for each compilation unit which references the |
| variable. |
| </p> |
| |
| |
| |
| </body> |
| </html> |
