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570 lines
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HTML
570 lines
27 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) 1988-2018 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 "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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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>Debugging Options (Using the GNU Compiler Collection (GCC))</title>
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<meta name="description" content="Debugging Options (Using the GNU Compiler Collection (GCC))">
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<meta name="keywords" content="Debugging Options (Using the GNU Compiler Collection (GCC))">
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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="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Invoking-GCC.html#Invoking-GCC" rel="up" title="Invoking GCC">
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<link href="Optimize-Options.html#Optimize-Options" rel="next" title="Optimize Options">
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<link href="Warning-Options.html#Warning-Options" rel="prev" title="Warning Options">
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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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div.smalllisp {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.menu-preformatted {font-family: serif}
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pre.smalldisplay {font-family: inherit; font-size: smaller}
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pre.smallexample {font-size: smaller}
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pre.smallformat {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="Debugging-Options"></a>
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<div class="header">
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<p>
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Next: <a href="Optimize-Options.html#Optimize-Options" accesskey="n" rel="next">Optimize Options</a>, Previous: <a href="Warning-Options.html#Warning-Options" accesskey="p" rel="prev">Warning Options</a>, Up: <a href="Invoking-GCC.html#Invoking-GCC" accesskey="u" rel="up">Invoking GCC</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>
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</div>
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<hr>
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<a name="Options-for-Debugging-Your-Program"></a>
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<h3 class="section">3.9 Options for Debugging Your Program</h3>
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<a name="index-options_002c-debugging"></a>
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<a name="index-debugging-information-options"></a>
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<p>To tell GCC to emit extra information for use by a debugger, in almost
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all cases you need only to add <samp>-g</samp> to your other options.
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</p>
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<p>GCC allows you to use <samp>-g</samp> with
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<samp>-O</samp>. The shortcuts taken by optimized code may occasionally
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be surprising: some variables you declared may not exist
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at all; flow of control may briefly move where you did not expect it;
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some statements may not be executed because they compute constant
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results or their values are already at hand; some statements may
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execute in different places because they have been moved out of loops.
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Nevertheless it is possible to debug optimized output. This makes
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it reasonable to use the optimizer for programs that might have bugs.
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</p>
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<p>If you are not using some other optimization option, consider
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using <samp>-Og</samp> (see <a href="Optimize-Options.html#Optimize-Options">Optimize Options</a>) with <samp>-g</samp>.
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With no <samp>-O</samp> option at all, some compiler passes that collect
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information useful for debugging do not run at all, so that
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<samp>-Og</samp> may result in a better debugging experience.
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</p>
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<dl compact="compact">
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<dt><code>-g</code></dt>
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<dd><a name="index-g"></a>
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<p>Produce debugging information in the operating system’s native format
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(stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging
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information.
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</p>
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<p>On most systems that use stabs format, <samp>-g</samp> enables use of extra
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debugging information that only GDB can use; this extra information
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makes debugging work better in GDB but probably makes other debuggers
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crash or
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refuse to read the program. If you want to control for certain whether
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to generate the extra information, use <samp>-gstabs+</samp>, <samp>-gstabs</samp>,
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<samp>-gxcoff+</samp>, <samp>-gxcoff</samp>, or <samp>-gvms</samp> (see below).
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</p>
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</dd>
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<dt><code>-ggdb</code></dt>
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<dd><a name="index-ggdb"></a>
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<p>Produce debugging information for use by GDB. This means to use the
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most expressive format available (DWARF, stabs, or the native format
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if neither of those are supported), including GDB extensions if at all
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possible.
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</p>
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</dd>
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<dt><code>-gdwarf</code></dt>
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<dt><code>-gdwarf-<var>version</var></code></dt>
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<dd><a name="index-gdwarf"></a>
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<p>Produce debugging information in DWARF format (if that is supported).
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The value of <var>version</var> may be either 2, 3, 4 or 5; the default version
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for most targets is 4. DWARF Version 5 is only experimental.
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</p>
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<p>Note that with DWARF Version 2, some ports require and always
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use some non-conflicting DWARF 3 extensions in the unwind tables.
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</p>
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<p>Version 4 may require GDB 7.0 and <samp>-fvar-tracking-assignments</samp>
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for maximum benefit.
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</p>
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<p>GCC no longer supports DWARF Version 1, which is substantially
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different than Version 2 and later. For historical reasons, some
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other DWARF-related options such as
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<samp>-fno-dwarf2-cfi-asm</samp>) retain a reference to DWARF Version 2
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in their names, but apply to all currently-supported versions of DWARF.
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</p>
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</dd>
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<dt><code>-gstabs</code></dt>
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<dd><a name="index-gstabs"></a>
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<p>Produce debugging information in stabs format (if that is supported),
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without GDB extensions. This is the format used by DBX on most BSD
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systems. On MIPS, Alpha and System V Release 4 systems this option
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produces stabs debugging output that is not understood by DBX.
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On System V Release 4 systems this option requires the GNU assembler.
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</p>
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</dd>
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<dt><code>-gstabs+</code></dt>
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<dd><a name="index-gstabs_002b"></a>
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<p>Produce debugging information in stabs format (if that is supported),
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using GNU extensions understood only by the GNU debugger (GDB). The
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use of these extensions is likely to make other debuggers crash or
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refuse to read the program.
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</p>
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</dd>
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<dt><code>-gxcoff</code></dt>
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<dd><a name="index-gxcoff"></a>
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<p>Produce debugging information in XCOFF format (if that is supported).
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This is the format used by the DBX debugger on IBM RS/6000 systems.
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</p>
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</dd>
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<dt><code>-gxcoff+</code></dt>
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<dd><a name="index-gxcoff_002b"></a>
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<p>Produce debugging information in XCOFF format (if that is supported),
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using GNU extensions understood only by the GNU debugger (GDB). The
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use of these extensions is likely to make other debuggers crash or
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refuse to read the program, and may cause assemblers other than the GNU
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assembler (GAS) to fail with an error.
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</p>
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</dd>
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<dt><code>-gvms</code></dt>
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<dd><a name="index-gvms"></a>
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<p>Produce debugging information in Alpha/VMS debug format (if that is
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supported). This is the format used by DEBUG on Alpha/VMS systems.
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</p>
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</dd>
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<dt><code>-g<var>level</var></code></dt>
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<dt><code>-ggdb<var>level</var></code></dt>
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<dt><code>-gstabs<var>level</var></code></dt>
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<dt><code>-gxcoff<var>level</var></code></dt>
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<dt><code>-gvms<var>level</var></code></dt>
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<dd><p>Request debugging information and also use <var>level</var> to specify how
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much information. The default level is 2.
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</p>
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<p>Level 0 produces no debug information at all. Thus, <samp>-g0</samp> negates
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<samp>-g</samp>.
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</p>
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<p>Level 1 produces minimal information, enough for making backtraces in
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parts of the program that you don’t plan to debug. This includes
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descriptions of functions and external variables, and line number
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tables, but no information about local variables.
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</p>
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<p>Level 3 includes extra information, such as all the macro definitions
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present in the program. Some debuggers support macro expansion when
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you use <samp>-g3</samp>.
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</p>
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<p><samp>-gdwarf</samp> does not accept a concatenated debug level, to avoid
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confusion with <samp>-gdwarf-<var>level</var></samp>.
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Instead use an additional <samp>-g<var>level</var></samp> option to change the
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debug level for DWARF.
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</p>
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</dd>
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<dt><code>-feliminate-unused-debug-symbols</code></dt>
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<dd><a name="index-feliminate_002dunused_002ddebug_002dsymbols"></a>
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<p>Produce debugging information in stabs format (if that is supported),
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for only symbols that are actually used.
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</p>
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</dd>
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<dt><code>-femit-class-debug-always</code></dt>
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<dd><a name="index-femit_002dclass_002ddebug_002dalways"></a>
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<p>Instead of emitting debugging information for a C++ class in only one
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object file, emit it in all object files using the class. This option
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should be used only with debuggers that are unable to handle the way GCC
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normally emits debugging information for classes because using this
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option increases the size of debugging information by as much as a
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factor of two.
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</p>
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</dd>
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<dt><code>-fno-merge-debug-strings</code></dt>
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<dd><a name="index-fmerge_002ddebug_002dstrings"></a>
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<a name="index-fno_002dmerge_002ddebug_002dstrings"></a>
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<p>Direct the linker to not merge together strings in the debugging
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information that are identical in different object files. Merging is
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not supported by all assemblers or linkers. Merging decreases the size
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of the debug information in the output file at the cost of increasing
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link processing time. Merging is enabled by default.
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</p>
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</dd>
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<dt><code>-fdebug-prefix-map=<var>old</var>=<var>new</var></code></dt>
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<dd><a name="index-fdebug_002dprefix_002dmap"></a>
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<p>When compiling files residing in directory <samp><var>old</var></samp>, record
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debugging information describing them as if the files resided in
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directory <samp><var>new</var></samp> instead. This can be used to replace a
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build-time path with an install-time path in the debug info. It can
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also be used to change an absolute path to a relative path by using
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<samp>.</samp> for <var>new</var>. This can give more reproducible builds, which
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are location independent, but may require an extra command to tell GDB
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where to find the source files. See also <samp>-ffile-prefix-map</samp>.
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</p>
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</dd>
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<dt><code>-fvar-tracking</code></dt>
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<dd><a name="index-fvar_002dtracking"></a>
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<p>Run variable tracking pass. It computes where variables are stored at each
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position in code. Better debugging information is then generated
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(if the debugging information format supports this information).
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</p>
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<p>It is enabled by default when compiling with optimization (<samp>-Os</samp>,
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<samp>-O</samp>, <samp>-O2</samp>, …), debugging information (<samp>-g</samp>) and
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the debug info format supports it.
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</p>
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</dd>
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<dt><code>-fvar-tracking-assignments</code></dt>
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<dd><a name="index-fvar_002dtracking_002dassignments"></a>
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<a name="index-fno_002dvar_002dtracking_002dassignments"></a>
|
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<p>Annotate assignments to user variables early in the compilation and
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attempt to carry the annotations over throughout the compilation all the
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way to the end, in an attempt to improve debug information while
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optimizing. Use of <samp>-gdwarf-4</samp> is recommended along with it.
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</p>
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<p>It can be enabled even if var-tracking is disabled, in which case
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annotations are created and maintained, but discarded at the end.
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By default, this flag is enabled together with <samp>-fvar-tracking</samp>,
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except when selective scheduling is enabled.
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</p>
|
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</dd>
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<dt><code>-gsplit-dwarf</code></dt>
|
||
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<dd><a name="index-gsplit_002ddwarf"></a>
|
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<p>Separate as much DWARF debugging information as possible into a
|
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separate output file with the extension <samp>.dwo</samp>. This option allows
|
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the build system to avoid linking files with debug information. To
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be useful, this option requires a debugger capable of reading <samp>.dwo</samp>
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||
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files.
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</p>
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||
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</dd>
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<dt><code>-gpubnames</code></dt>
|
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<dd><a name="index-gpubnames"></a>
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<p>Generate DWARF <code>.debug_pubnames</code> and <code>.debug_pubtypes</code> sections.
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</p>
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</dd>
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<dt><code>-ggnu-pubnames</code></dt>
|
||
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<dd><a name="index-ggnu_002dpubnames"></a>
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<p>Generate <code>.debug_pubnames</code> and <code>.debug_pubtypes</code> sections in a format
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suitable for conversion into a GDB index. This option is only useful
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with a linker that can produce GDB index version 7.
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</p>
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</dd>
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<dt><code>-fdebug-types-section</code></dt>
|
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<dd><a name="index-fdebug_002dtypes_002dsection"></a>
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||
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<a name="index-fno_002ddebug_002dtypes_002dsection"></a>
|
||
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<p>When using DWARF Version 4 or higher, type DIEs can be put into
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their own <code>.debug_types</code> section instead of making them part of the
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|
|
<code>.debug_info</code> section. It is more efficient to put them in a separate
|
||
|
|
comdat sections since the linker can then remove duplicates.
|
||
|
|
But not all DWARF consumers support <code>.debug_types</code> sections yet
|
||
|
|
and on some objects <code>.debug_types</code> produces larger instead of smaller
|
||
|
|
debugging information.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-grecord-gcc-switches</code></dt>
|
||
|
|
<dt><code>-gno-record-gcc-switches</code></dt>
|
||
|
|
<dd><a name="index-grecord_002dgcc_002dswitches"></a>
|
||
|
|
<a name="index-gno_002drecord_002dgcc_002dswitches"></a>
|
||
|
|
<p>This switch causes the command-line options used to invoke the
|
||
|
|
compiler that may affect code generation to be appended to the
|
||
|
|
DW_AT_producer attribute in DWARF debugging information. The options
|
||
|
|
are concatenated with spaces separating them from each other and from
|
||
|
|
the compiler version.
|
||
|
|
It is enabled by default.
|
||
|
|
See also <samp>-frecord-gcc-switches</samp> for another
|
||
|
|
way of storing compiler options into the object file.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gstrict-dwarf</code></dt>
|
||
|
|
<dd><a name="index-gstrict_002ddwarf"></a>
|
||
|
|
<p>Disallow using extensions of later DWARF standard version than selected
|
||
|
|
with <samp>-gdwarf-<var>version</var></samp>. On most targets using non-conflicting
|
||
|
|
DWARF extensions from later standard versions is allowed.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gno-strict-dwarf</code></dt>
|
||
|
|
<dd><a name="index-gno_002dstrict_002ddwarf"></a>
|
||
|
|
<p>Allow using extensions of later DWARF standard version than selected with
|
||
|
|
<samp>-gdwarf-<var>version</var></samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gas-loc-support</code></dt>
|
||
|
|
<dd><a name="index-gas_002dloc_002dsupport"></a>
|
||
|
|
<p>Inform the compiler that the assembler supports <code>.loc</code> directives.
|
||
|
|
It may then use them for the assembler to generate DWARF2+ line number
|
||
|
|
tables.
|
||
|
|
</p>
|
||
|
|
<p>This is generally desirable, because assembler-generated line-number
|
||
|
|
tables are a lot more compact than those the compiler can generate
|
||
|
|
itself.
|
||
|
|
</p>
|
||
|
|
<p>This option will be enabled by default if, at GCC configure time, the
|
||
|
|
assembler was found to support such directives.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gno-as-loc-support</code></dt>
|
||
|
|
<dd><a name="index-gno_002das_002dloc_002dsupport"></a>
|
||
|
|
<p>Force GCC to generate DWARF2+ line number tables internally, if DWARF2+
|
||
|
|
line number tables are to be generated.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>gas-locview-support</code></dt>
|
||
|
|
<dd><a name="index-gas_002dlocview_002dsupport"></a>
|
||
|
|
<p>Inform the compiler that the assembler supports <code>view</code> assignment
|
||
|
|
and reset assertion checking in <code>.loc</code> directives.
|
||
|
|
</p>
|
||
|
|
<p>This option will be enabled by default if, at GCC configure time, the
|
||
|
|
assembler was found to support them.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>gno-as-locview-support</code></dt>
|
||
|
|
<dd><p>Force GCC to assign view numbers internally, if
|
||
|
|
<samp>-gvariable-location-views</samp> are explicitly requested.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gcolumn-info</code></dt>
|
||
|
|
<dt><code>-gno-column-info</code></dt>
|
||
|
|
<dd><a name="index-gcolumn_002dinfo"></a>
|
||
|
|
<a name="index-gno_002dcolumn_002dinfo"></a>
|
||
|
|
<p>Emit location column information into DWARF debugging information, rather
|
||
|
|
than just file and line.
|
||
|
|
This option is enabled by default.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gstatement-frontiers</code></dt>
|
||
|
|
<dt><code>-gno-statement-frontiers</code></dt>
|
||
|
|
<dd><a name="index-gstatement_002dfrontiers"></a>
|
||
|
|
<a name="index-gno_002dstatement_002dfrontiers"></a>
|
||
|
|
<p>This option causes GCC to create markers in the internal representation
|
||
|
|
at the beginning of statements, and to keep them roughly in place
|
||
|
|
throughout compilation, using them to guide the output of <code>is_stmt</code>
|
||
|
|
markers in the line number table. This is enabled by default when
|
||
|
|
compiling with optimization (<samp>-Os</samp>, <samp>-O</samp>, <samp>-O2</samp>,
|
||
|
|
…), and outputting DWARF 2 debug information at the normal level.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gvariable-location-views</code></dt>
|
||
|
|
<dt><code>-gvariable-location-views=incompat5</code></dt>
|
||
|
|
<dt><code>-gno-variable-location-views</code></dt>
|
||
|
|
<dd><a name="index-gvariable_002dlocation_002dviews"></a>
|
||
|
|
<a name="index-gvariable_002dlocation_002dviews_003dincompat5"></a>
|
||
|
|
<a name="index-gno_002dvariable_002dlocation_002dviews"></a>
|
||
|
|
<p>Augment variable location lists with progressive view numbers implied
|
||
|
|
from the line number table. This enables debug information consumers to
|
||
|
|
inspect state at certain points of the program, even if no instructions
|
||
|
|
associated with the corresponding source locations are present at that
|
||
|
|
point. If the assembler lacks support for view numbers in line number
|
||
|
|
tables, this will cause the compiler to emit the line number table,
|
||
|
|
which generally makes them somewhat less compact. The augmented line
|
||
|
|
number tables and location lists are fully backward-compatible, so they
|
||
|
|
can be consumed by debug information consumers that are not aware of
|
||
|
|
these augmentations, but they won’t derive any benefit from them either.
|
||
|
|
</p>
|
||
|
|
<p>This is enabled by default when outputting DWARF 2 debug information at
|
||
|
|
the normal level, as long as there is assembler support,
|
||
|
|
<samp>-fvar-tracking-assignments</samp> is enabled and
|
||
|
|
<samp>-gstrict-dwarf</samp> is not. When assembler support is not
|
||
|
|
available, this may still be enabled, but it will force GCC to output
|
||
|
|
internal line number tables, and if
|
||
|
|
<samp>-ginternal-reset-location-views</samp> is not enabled, that will most
|
||
|
|
certainly lead to silently mismatching location views.
|
||
|
|
</p>
|
||
|
|
<p>There is a proposed representation for view numbers that is not backward
|
||
|
|
compatible with the location list format introduced in DWARF 5, that can
|
||
|
|
be enabled with <samp>-gvariable-location-views=incompat5</samp>. This
|
||
|
|
option may be removed in the future, is only provided as a reference
|
||
|
|
implementation of the proposed representation. Debug information
|
||
|
|
consumers are not expected to support this extended format, and they
|
||
|
|
would be rendered unable to decode location lists using it.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-ginternal-reset-location-views</code></dt>
|
||
|
|
<dt><code>-gnointernal-reset-location-views</code></dt>
|
||
|
|
<dd><a name="index-ginternal_002dreset_002dlocation_002dviews"></a>
|
||
|
|
<a name="index-gno_002dinternal_002dreset_002dlocation_002dviews"></a>
|
||
|
|
<p>Attempt to determine location views that can be omitted from location
|
||
|
|
view lists. This requires the compiler to have very accurate insn
|
||
|
|
length estimates, which isn’t always the case, and it may cause
|
||
|
|
incorrect view lists to be generated silently when using an assembler
|
||
|
|
that does not support location view lists. The GNU assembler will flag
|
||
|
|
any such error as a <code>view number mismatch</code>. This is only enabled
|
||
|
|
on ports that define a reliable estimation function.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-ginline-points</code></dt>
|
||
|
|
<dt><code>-gno-inline-points</code></dt>
|
||
|
|
<dd><a name="index-ginline_002dpoints"></a>
|
||
|
|
<a name="index-gno_002dinline_002dpoints"></a>
|
||
|
|
<p>Generate extended debug information for inlined functions. Location
|
||
|
|
view tracking markers are inserted at inlined entry points, so that
|
||
|
|
address and view numbers can be computed and output in debug
|
||
|
|
information. This can be enabled independently of location views, in
|
||
|
|
which case the view numbers won’t be output, but it can only be enabled
|
||
|
|
along with statement frontiers, and it is only enabled by default if
|
||
|
|
location views are enabled.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-gz<span class="roman">[</span>=<var>type</var><span class="roman">]</span></code></dt>
|
||
|
|
<dd><a name="index-gz"></a>
|
||
|
|
<p>Produce compressed debug sections in DWARF format, if that is supported.
|
||
|
|
If <var>type</var> is not given, the default type depends on the capabilities
|
||
|
|
of the assembler and linker used. <var>type</var> may be one of
|
||
|
|
‘<samp>none</samp>’ (don’t compress debug sections), ‘<samp>zlib</samp>’ (use zlib
|
||
|
|
compression in ELF gABI format), or ‘<samp>zlib-gnu</samp>’ (use zlib
|
||
|
|
compression in traditional GNU format). If the linker doesn’t support
|
||
|
|
writing compressed debug sections, the option is rejected. Otherwise,
|
||
|
|
if the assembler does not support them, <samp>-gz</samp> is silently ignored
|
||
|
|
when producing object files.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-femit-struct-debug-baseonly</code></dt>
|
||
|
|
<dd><a name="index-femit_002dstruct_002ddebug_002dbaseonly"></a>
|
||
|
|
<p>Emit debug information for struct-like types
|
||
|
|
only when the base name of the compilation source file
|
||
|
|
matches the base name of file in which the struct is defined.
|
||
|
|
</p>
|
||
|
|
<p>This option substantially reduces the size of debugging information,
|
||
|
|
but at significant potential loss in type information to the debugger.
|
||
|
|
See <samp>-femit-struct-debug-reduced</samp> for a less aggressive option.
|
||
|
|
See <samp>-femit-struct-debug-detailed</samp> for more detailed control.
|
||
|
|
</p>
|
||
|
|
<p>This option works only with DWARF debug output.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-femit-struct-debug-reduced</code></dt>
|
||
|
|
<dd><a name="index-femit_002dstruct_002ddebug_002dreduced"></a>
|
||
|
|
<p>Emit debug information for struct-like types
|
||
|
|
only when the base name of the compilation source file
|
||
|
|
matches the base name of file in which the type is defined,
|
||
|
|
unless the struct is a template or defined in a system header.
|
||
|
|
</p>
|
||
|
|
<p>This option significantly reduces the size of debugging information,
|
||
|
|
with some potential loss in type information to the debugger.
|
||
|
|
See <samp>-femit-struct-debug-baseonly</samp> for a more aggressive option.
|
||
|
|
See <samp>-femit-struct-debug-detailed</samp> for more detailed control.
|
||
|
|
</p>
|
||
|
|
<p>This option works only with DWARF debug output.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-femit-struct-debug-detailed<span class="roman">[</span>=<var>spec-list</var><span class="roman">]</span></code></dt>
|
||
|
|
<dd><a name="index-femit_002dstruct_002ddebug_002ddetailed"></a>
|
||
|
|
<p>Specify the struct-like types
|
||
|
|
for which the compiler generates debug information.
|
||
|
|
The intent is to reduce duplicate struct debug information
|
||
|
|
between different object files within the same program.
|
||
|
|
</p>
|
||
|
|
<p>This option is a detailed version of
|
||
|
|
<samp>-femit-struct-debug-reduced</samp> and <samp>-femit-struct-debug-baseonly</samp>,
|
||
|
|
which serves for most needs.
|
||
|
|
</p>
|
||
|
|
<p>A specification has the syntax<br>
|
||
|
|
[‘<samp>dir:</samp>’|‘<samp>ind:</samp>’][‘<samp>ord:</samp>’|‘<samp>gen:</samp>’](‘<samp>any</samp>’|‘<samp>sys</samp>’|‘<samp>base</samp>’|‘<samp>none</samp>’)
|
||
|
|
</p>
|
||
|
|
<p>The optional first word limits the specification to
|
||
|
|
structs that are used directly (‘<samp>dir:</samp>’) or used indirectly (‘<samp>ind:</samp>’).
|
||
|
|
A struct type is used directly when it is the type of a variable, member.
|
||
|
|
Indirect uses arise through pointers to structs.
|
||
|
|
That is, when use of an incomplete struct is valid, the use is indirect.
|
||
|
|
An example is
|
||
|
|
‘<samp>struct one direct; struct two * indirect;</samp>’.
|
||
|
|
</p>
|
||
|
|
<p>The optional second word limits the specification to
|
||
|
|
ordinary structs (‘<samp>ord:</samp>’) or generic structs (‘<samp>gen:</samp>’).
|
||
|
|
Generic structs are a bit complicated to explain.
|
||
|
|
For C++, these are non-explicit specializations of template classes,
|
||
|
|
or non-template classes within the above.
|
||
|
|
Other programming languages have generics,
|
||
|
|
but <samp>-femit-struct-debug-detailed</samp> does not yet implement them.
|
||
|
|
</p>
|
||
|
|
<p>The third word specifies the source files for those
|
||
|
|
structs for which the compiler should emit debug information.
|
||
|
|
The values ‘<samp>none</samp>’ and ‘<samp>any</samp>’ have the normal meaning.
|
||
|
|
The value ‘<samp>base</samp>’ means that
|
||
|
|
the base of name of the file in which the type declaration appears
|
||
|
|
must match the base of the name of the main compilation file.
|
||
|
|
In practice, this means that when compiling <samp>foo.c</samp>, debug information
|
||
|
|
is generated for types declared in that file and <samp>foo.h</samp>,
|
||
|
|
but not other header files.
|
||
|
|
The value ‘<samp>sys</samp>’ means those types satisfying ‘<samp>base</samp>’
|
||
|
|
or declared in system or compiler headers.
|
||
|
|
</p>
|
||
|
|
<p>You may need to experiment to determine the best settings for your application.
|
||
|
|
</p>
|
||
|
|
<p>The default is <samp>-femit-struct-debug-detailed=all</samp>.
|
||
|
|
</p>
|
||
|
|
<p>This option works only with DWARF debug output.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-fno-dwarf2-cfi-asm</code></dt>
|
||
|
|
<dd><a name="index-fdwarf2_002dcfi_002dasm"></a>
|
||
|
|
<a name="index-fno_002ddwarf2_002dcfi_002dasm"></a>
|
||
|
|
<p>Emit DWARF unwind info as compiler generated <code>.eh_frame</code> section
|
||
|
|
instead of using GAS <code>.cfi_*</code> directives.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-fno-eliminate-unused-debug-types</code></dt>
|
||
|
|
<dd><a name="index-feliminate_002dunused_002ddebug_002dtypes"></a>
|
||
|
|
<a name="index-fno_002deliminate_002dunused_002ddebug_002dtypes"></a>
|
||
|
|
<p>Normally, when producing DWARF output, GCC avoids producing debug symbol
|
||
|
|
output for types that are nowhere used in the source file being compiled.
|
||
|
|
Sometimes it is useful to have GCC emit debugging
|
||
|
|
information for all types declared in a compilation
|
||
|
|
unit, regardless of whether or not they are actually used
|
||
|
|
in that compilation unit, for example
|
||
|
|
if, in the debugger, you want to cast a value to a type that is
|
||
|
|
not actually used in your program (but is declared). More often,
|
||
|
|
however, this results in a significant amount of wasted space.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Optimize-Options.html#Optimize-Options" accesskey="n" rel="next">Optimize Options</a>, Previous: <a href="Warning-Options.html#Warning-Options" accesskey="p" rel="prev">Warning Options</a>, Up: <a href="Invoking-GCC.html#Invoking-GCC" accesskey="u" rel="up">Invoking GCC</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>
|