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129 lines
6.0 KiB
HTML
129 lines
6.0 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Free Software" and "Free Software Needs
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Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: "You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom." -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Jumping (Debugging with GDB)</title>
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<meta name="description" content="Jumping (Debugging with GDB)">
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<meta name="keywords" content="Jumping (Debugging with GDB)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Altering.html#Altering" rel="up" title="Altering">
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<link href="Signaling.html#Signaling" rel="next" title="Signaling">
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<link href="Assignment.html#Assignment" rel="prev" title="Assignment">
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<style type="text/css">
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<!--
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a.summary-letter {text-decoration: none}
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blockquote.indentedblock {margin-right: 0em}
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blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
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blockquote.smallquotation {font-size: smaller}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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div.lisp {margin-left: 3.2em}
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div.smalldisplay {margin-left: 3.2em}
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kbd {font-style: oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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pre.menu-comment {font-family: serif}
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pre.smalldisplay {font-family: inherit; font-size: smaller}
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pre.smalllisp {font-size: smaller}
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span.nolinebreak {white-space: nowrap}
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span.roman {font-family: initial; font-weight: normal}
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span.sansserif {font-family: sans-serif; font-weight: normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Jumping"></a>
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<div class="header">
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<p>
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Next: <a href="Signaling.html#Signaling" accesskey="n" rel="next">Signaling</a>, Previous: <a href="Assignment.html#Assignment" accesskey="p" rel="prev">Assignment</a>, Up: <a href="Altering.html#Altering" accesskey="u" rel="up">Altering</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>
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</div>
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<hr>
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<a name="Continuing-at-a-Different-Address"></a>
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<h3 class="section">17.2 Continuing at a Different Address</h3>
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<p>Ordinarily, when you continue your program, you do so at the place where
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it stopped, with the <code>continue</code> command. You can instead continue at
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an address of your own choosing, with the following commands:
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</p>
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<dl compact="compact">
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<dd><a name="index-jump"></a>
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<a name="index-j-_0028jump_0029"></a>
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</dd>
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<dt><code>jump <var>location</var></code></dt>
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<dt><code>j <var>location</var></code></dt>
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<dd><p>Resume execution at <var>location</var>. Execution stops again immediately
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if there is a breakpoint there. See <a href="Specify-Location.html#Specify-Location">Specify Location</a>, for a description
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of the different forms of <var>location</var>. It is common
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practice to use the <code>tbreak</code> command in conjunction with
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<code>jump</code>. See <a href="Set-Breaks.html#Set-Breaks">Setting Breakpoints</a>.
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</p>
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<p>The <code>jump</code> command does not change the current stack frame, or
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the stack pointer, or the contents of any memory location or any
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register other than the program counter. If <var>location</var> is in
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a different function from the one currently executing, the results may
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be bizarre if the two functions expect different patterns of arguments or
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of local variables. For this reason, the <code>jump</code> command requests
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confirmation if the specified line is not in the function currently
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executing. However, even bizarre results are predictable if you are
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well acquainted with the machine-language code of your program.
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</p></dd>
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</dl>
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<p>On many systems, you can get much the same effect as the <code>jump</code>
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command by storing a new value into the register <code>$pc</code>. The
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difference is that this does not start your program running; it only
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changes the address of where it <em>will</em> run when you continue. For
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example,
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</p>
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<div class="smallexample">
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<pre class="smallexample">set $pc = 0x485
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</pre></div>
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<p>makes the next <code>continue</code> command or stepping command execute at
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address <code>0x485</code>, rather than at the address where your program stopped.
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See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">Continuing and Stepping</a>.
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</p>
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<p>The most common occasion to use the <code>jump</code> command is to back
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up—perhaps with more breakpoints set—over a portion of a program
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that has already executed, in order to examine its execution in more
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detail.
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</p>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Signaling.html#Signaling" accesskey="n" rel="next">Signaling</a>, Previous: <a href="Assignment.html#Assignment" accesskey="p" rel="prev">Assignment</a>, Up: <a href="Altering.html#Altering" accesskey="u" rel="up">Altering</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>
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</div>
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</body>
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</html>
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