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.
134 lines
6.2 KiB
HTML
134 lines
6.2 KiB
HTML
4 years ago
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html>
|
||
|
|
<!-- Copyright (C) 1988-2019 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 "Free Software" and "Free Software Needs
|
||
|
|
Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
|
||
|
|
and with the Back-Cover Texts as in (a) below.
|
||
|
|
|
||
|
|
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
|
||
|
|
this GNU Manual. Buying copies from GNU Press supports the FSF in
|
||
|
|
developing GNU and promoting software freedom." -->
|
||
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<title>Frames (Debugging with GDB)</title>
|
||
|
|
|
||
|
|
<meta name="description" content="Frames (Debugging with GDB)">
|
||
|
|
<meta name="keywords" content="Frames (Debugging with GDB)">
|
||
|
|
<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="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
||
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
||
|
|
<link href="Stack.html#Stack" rel="up" title="Stack">
|
||
|
|
<link href="Backtrace.html#Backtrace" rel="next" title="Backtrace">
|
||
|
|
<link href="Stack.html#Stack" rel="prev" title="Stack">
|
||
|
|
<style type="text/css">
|
||
|
|
<!--
|
||
|
|
a.summary-letter {text-decoration: none}
|
||
|
|
blockquote.indentedblock {margin-right: 0em}
|
||
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
||
|
|
blockquote.smallquotation {font-size: smaller}
|
||
|
|
div.display {margin-left: 3.2em}
|
||
|
|
div.example {margin-left: 3.2em}
|
||
|
|
div.lisp {margin-left: 3.2em}
|
||
|
|
div.smalldisplay {margin-left: 3.2em}
|
||
|
|
div.smallexample {margin-left: 3.2em}
|
||
|
|
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.nolinebreak {white-space: nowrap}
|
||
|
|
span.roman {font-family: initial; font-weight: normal}
|
||
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
||
|
|
ul.no-bullet {list-style: none}
|
||
|
|
-->
|
||
|
|
</style>
|
||
|
|
|
||
|
|
|
||
|
|
</head>
|
||
|
|
|
||
|
|
<body lang="en">
|
||
|
|
<a name="Frames"></a>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Backtrace.html#Backtrace" accesskey="n" rel="next">Backtrace</a>, Up: <a href="Stack.html#Stack" accesskey="u" rel="up">Stack</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<a name="Stack-Frames"></a>
|
||
|
|
<h3 class="section">8.1 Stack Frames</h3>
|
||
|
|
|
||
|
|
<a name="index-frame_002c-definition"></a>
|
||
|
|
<a name="index-stack-frame"></a>
|
||
|
|
<p>The call stack is divided up into contiguous pieces called <em>stack
|
||
|
|
frames</em>, or <em>frames</em> for short; each frame is the data associated
|
||
|
|
with one call to one function. The frame contains the arguments given
|
||
|
|
to the function, the function’s local variables, and the address at
|
||
|
|
which the function is executing.
|
||
|
|
</p>
|
||
|
|
<a name="index-initial-frame"></a>
|
||
|
|
<a name="index-outermost-frame"></a>
|
||
|
|
<a name="index-innermost-frame"></a>
|
||
|
|
<p>When your program is started, the stack has only one frame, that of the
|
||
|
|
function <code>main</code>. This is called the <em>initial</em> frame or the
|
||
|
|
<em>outermost</em> frame. Each time a function is called, a new frame is
|
||
|
|
made. Each time a function returns, the frame for that function invocation
|
||
|
|
is eliminated. If a function is recursive, there can be many frames for
|
||
|
|
the same function. The frame for the function in which execution is
|
||
|
|
actually occurring is called the <em>innermost</em> frame. This is the most
|
||
|
|
recently created of all the stack frames that still exist.
|
||
|
|
</p>
|
||
|
|
<a name="index-frame-pointer"></a>
|
||
|
|
<p>Inside your program, stack frames are identified by their addresses. A
|
||
|
|
stack frame consists of many bytes, each of which has its own address; each
|
||
|
|
kind of computer has a convention for choosing one byte whose
|
||
|
|
address serves as the address of the frame. Usually this address is kept
|
||
|
|
in a register called the <em>frame pointer register</em>
|
||
|
|
(see <a href="Registers.html#Registers">$fp</a>) while execution is going on in that frame.
|
||
|
|
</p>
|
||
|
|
<a name="index-frame-level"></a>
|
||
|
|
<a name="index-frame-number"></a>
|
||
|
|
<p><small>GDB</small> labels each existing stack frame with a <em>level</em>, a
|
||
|
|
number that is zero for the innermost frame, one for the frame that
|
||
|
|
called it, and so on upward. These level numbers give you a way of
|
||
|
|
designating stack frames in <small>GDB</small> commands. The terms
|
||
|
|
<em>frame number</em> and <em>frame level</em> can be used interchangeably to
|
||
|
|
describe this number.
|
||
|
|
</p>
|
||
|
|
<a name="index-frameless-execution"></a>
|
||
|
|
<p>Some compilers provide a way to compile functions so that they operate
|
||
|
|
without stack frames. (For example, the <small>GCC</small> option
|
||
|
|
</p><div class="smallexample">
|
||
|
|
<pre class="smallexample">‘<samp>-fomit-frame-pointer</samp>’
|
||
|
|
</pre></div>
|
||
|
|
<p>generates functions without a frame.)
|
||
|
|
This is occasionally done with heavily used library functions to save
|
||
|
|
the frame setup time. <small>GDB</small> has limited facilities for dealing
|
||
|
|
with these function invocations. If the innermost function invocation
|
||
|
|
has no stack frame, <small>GDB</small> nevertheless regards it as though
|
||
|
|
it had a separate frame, which is numbered zero as usual, allowing
|
||
|
|
correct tracing of the function call chain. However, <small>GDB</small> has
|
||
|
|
no provision for frameless functions elsewhere in the stack.
|
||
|
|
</p>
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Backtrace.html#Backtrace" accesskey="n" rel="next">Backtrace</a>, Up: <a href="Stack.html#Stack" accesskey="u" rel="up">Stack</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|