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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gcc/Overall-Options.html | |
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diff --git a/share/doc/gcc/Overall-Options.html b/share/doc/gcc/Overall-Options.html new file mode 100644 index 0000000..2ca92a5 --- /dev/null +++ b/share/doc/gcc/Overall-Options.html @@ -0,0 +1,936 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- This file documents the use of the GNU compilers. + +Copyright (C) 1988-2023 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 "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Using the GNU Compiler Collection (GCC): Overall Options</title> + +<meta name="description" content="Using the GNU Compiler Collection (GCC): Overall Options"> +<meta name="keywords" content="Using the GNU Compiler Collection (GCC): Overall Options"> +<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="Indices.html#Indices" rel="index" title="Indices"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Invoking-GCC.html#Invoking-GCC" rel="up" title="Invoking GCC"> +<link href="Invoking-G_002b_002b.html#Invoking-G_002b_002b" rel="next" title="Invoking G++"> +<link href="Option-Summary.html#Option-Summary" rel="previous" title="Option Summary"> +<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_US" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Overall-Options"></a> +<div class="header"> +<p> +Next: <a href="Invoking-G_002b_002b.html#Invoking-G_002b_002b" accesskey="n" rel="next">Invoking G++</a>, Previous: <a href="Option-Summary.html#Option-Summary" accesskey="p" rel="previous">Option Summary</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="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Options-Controlling-the-Kind-of-Output"></a> +<h3 class="section">3.2 Options Controlling the Kind of Output</h3> + +<p>Compilation can involve up to four stages: preprocessing, compilation +proper, assembly and linking, always in that order. GCC is capable of +preprocessing and compiling several files either into several +assembler input files, or into one assembler input file; then each +assembler input file produces an object file, and linking combines all +the object files (those newly compiled, and those specified as input) +into an executable file. +</p> +<a name="index-file-name-suffix"></a> +<p>For any given input file, the file name suffix determines what kind of +compilation is done: +</p> +<dl compact="compact"> +<dt><code><var>file</var>.c</code></dt> +<dd><p>C source code that must be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.i</code></dt> +<dd><p>C source code that should not be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.ii</code></dt> +<dd><p>C++ source code that should not be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.m</code></dt> +<dd><p>Objective-C source code. Note that you must link with the <samp>libobjc</samp> +library to make an Objective-C program work. +</p> +</dd> +<dt><code><var>file</var>.mi</code></dt> +<dd><p>Objective-C source code that should not be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.mm</code></dt> +<dt><code><var>file</var>.M</code></dt> +<dd><p>Objective-C++ source code. Note that you must link with the <samp>libobjc</samp> +library to make an Objective-C++ program work. Note that ‘<samp>.M</samp>’ refers +to a literal capital M. +</p> +</dd> +<dt><code><var>file</var>.mii</code></dt> +<dd><p>Objective-C++ source code that should not be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.h</code></dt> +<dd><p>C, C++, Objective-C or Objective-C++ header file to be turned into a +precompiled header (default), or C, C++ header file to be turned into an +Ada spec (via the <samp>-fdump-ada-spec</samp> switch). +</p> +</dd> +<dt><code><var>file</var>.cc</code></dt> +<dt><code><var>file</var>.cp</code></dt> +<dt><code><var>file</var>.cxx</code></dt> +<dt><code><var>file</var>.cpp</code></dt> +<dt><code><var>file</var>.CPP</code></dt> +<dt><code><var>file</var>.c++</code></dt> +<dt><code><var>file</var>.C</code></dt> +<dd><p>C++ source code that must be preprocessed. Note that in ‘<samp>.cxx</samp>’, +the last two letters must both be literally ‘<samp>x</samp>’. Likewise, +‘<samp>.C</samp>’ refers to a literal capital C. +</p> +</dd> +<dt><code><var>file</var>.mm</code></dt> +<dt><code><var>file</var>.M</code></dt> +<dd><p>Objective-C++ source code that must be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.mii</code></dt> +<dd><p>Objective-C++ source code that should not be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.hh</code></dt> +<dt><code><var>file</var>.H</code></dt> +<dt><code><var>file</var>.hp</code></dt> +<dt><code><var>file</var>.hxx</code></dt> +<dt><code><var>file</var>.hpp</code></dt> +<dt><code><var>file</var>.HPP</code></dt> +<dt><code><var>file</var>.h++</code></dt> +<dt><code><var>file</var>.tcc</code></dt> +<dd><p>C++ header file to be turned into a precompiled header or Ada spec. +</p> +</dd> +<dt><code><var>file</var>.f</code></dt> +<dt><code><var>file</var>.for</code></dt> +<dt><code><var>file</var>.ftn</code></dt> +<dd><p>Fixed form Fortran source code that should not be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.F</code></dt> +<dt><code><var>file</var>.FOR</code></dt> +<dt><code><var>file</var>.fpp</code></dt> +<dt><code><var>file</var>.FPP</code></dt> +<dt><code><var>file</var>.FTN</code></dt> +<dd><p>Fixed form Fortran source code that must be preprocessed (with the traditional +preprocessor). +</p> +</dd> +<dt><code><var>file</var>.f90</code></dt> +<dt><code><var>file</var>.f95</code></dt> +<dt><code><var>file</var>.f03</code></dt> +<dt><code><var>file</var>.f08</code></dt> +<dd><p>Free form Fortran source code that should not be preprocessed. +</p> +</dd> +<dt><code><var>file</var>.F90</code></dt> +<dt><code><var>file</var>.F95</code></dt> +<dt><code><var>file</var>.F03</code></dt> +<dt><code><var>file</var>.F08</code></dt> +<dd><p>Free form Fortran source code that must be preprocessed (with the +traditional preprocessor). +</p> +</dd> +<dt><code><var>file</var>.go</code></dt> +<dd><p>Go source code. +</p> +</dd> +<dt><code><var>file</var>.d</code></dt> +<dd><p>D source code. +</p> +</dd> +<dt><code><var>file</var>.di</code></dt> +<dd><p>D interface file. +</p> +</dd> +<dt><code><var>file</var>.dd</code></dt> +<dd><p>D documentation code (Ddoc). +</p> +</dd> +<dt><code><var>file</var>.ads</code></dt> +<dd><p>Ada source code file that contains a library unit declaration (a +declaration of a package, subprogram, or generic, or a generic +instantiation), or a library unit renaming declaration (a package, +generic, or subprogram renaming declaration). Such files are also +called <em>specs</em>. +</p> +</dd> +<dt><code><var>file</var>.adb</code></dt> +<dd><p>Ada source code file containing a library unit body (a subprogram or +package body). Such files are also called <em>bodies</em>. +</p> + +</dd> +<dt><code><var>file</var>.s</code></dt> +<dd><p>Assembler code. +</p> +</dd> +<dt><code><var>file</var>.S</code></dt> +<dt><code><var>file</var>.sx</code></dt> +<dd><p>Assembler code that must be preprocessed. +</p> +</dd> +<dt><code><var>other</var></code></dt> +<dd><p>An object file to be fed straight into linking. +Any file name with no recognized suffix is treated this way. +</p></dd> +</dl> + +<a name="index-x"></a> +<p>You can specify the input language explicitly with the <samp>-x</samp> option: +</p> +<dl compact="compact"> +<dt><code>-x <var>language</var></code></dt> +<dd><p>Specify explicitly the <var>language</var> for the following input files +(rather than letting the compiler choose a default based on the file +name suffix). This option applies to all following input files until +the next <samp>-x</samp> option. Possible values for <var>language</var> are: +</p><div class="smallexample"> +<pre class="smallexample">c c-header cpp-output +c++ c++-header c++-system-header c++-user-header c++-cpp-output +objective-c objective-c-header objective-c-cpp-output +objective-c++ objective-c++-header objective-c++-cpp-output +assembler assembler-with-cpp +ada +d +f77 f77-cpp-input f95 f95-cpp-input +go +</pre></div> + +</dd> +<dt><code>-x none</code></dt> +<dd><p>Turn off any specification of a language, so that subsequent files are +handled according to their file name suffixes (as they are if <samp>-x</samp> +has not been used at all). +</p></dd> +</dl> + +<p>If you only want some of the stages of compilation, you can use +<samp>-x</samp> (or filename suffixes) to tell <code>gcc</code> where to start, and +one of the options <samp>-c</samp>, <samp>-S</samp>, or <samp>-E</samp> to say where +<code>gcc</code> is to stop. Note that some combinations (for example, +‘<samp>-x cpp-output -E</samp>’) instruct <code>gcc</code> to do nothing at all. +</p> +<dl compact="compact"> +<dd><a name="index-c"></a> +</dd> +<dt><code>-c</code></dt> +<dd><p>Compile or assemble the source files, but do not link. The linking +stage simply is not done. The ultimate output is in the form of an +object file for each source file. +</p> +<p>By default, the object file name for a source file is made by replacing +the suffix ‘<samp>.c</samp>’, ‘<samp>.i</samp>’, ‘<samp>.s</samp>’, etc., with ‘<samp>.o</samp>’. +</p> +<p>Unrecognized input files, not requiring compilation or assembly, are +ignored. +</p> +<a name="index-S"></a> +</dd> +<dt><code>-S</code></dt> +<dd><p>Stop after the stage of compilation proper; do not assemble. The output +is in the form of an assembler code file for each non-assembler input +file specified. +</p> +<p>By default, the assembler file name for a source file is made by +replacing the suffix ‘<samp>.c</samp>’, ‘<samp>.i</samp>’, etc., with ‘<samp>.s</samp>’. +</p> +<p>Input files that don’t require compilation are ignored. +</p> +<a name="index-E"></a> +</dd> +<dt><code>-E</code></dt> +<dd><p>Stop after the preprocessing stage; do not run the compiler proper. The +output is in the form of preprocessed source code, which is sent to the +standard output. +</p> +<p>Input files that don’t require preprocessing are ignored. +</p> +<a name="index-output-file-option"></a> +<a name="index-o"></a> +</dd> +<dt><code>-o <var>file</var></code></dt> +<dd><p>Place the primary output in file <var>file</var>. This applies to whatever +sort of output is being produced, whether it be an executable file, an +object file, an assembler file or preprocessed C code. +</p> +<p>If <samp>-o</samp> is not specified, the default is to put an executable +file in <samp>a.out</samp>, the object file for +<samp><var>source</var>.<var>suffix</var></samp> in <samp><var>source</var>.o</samp>, its +assembler file in <samp><var>source</var>.s</samp>, a precompiled header file in +<samp><var>source</var>.<var>suffix</var>.gch</samp>, and all preprocessed C source on +standard output. +</p> +<p>Though <samp>-o</samp> names only the primary output, it also affects the +naming of auxiliary and dump outputs. See the examples below. Unless +overridden, both auxiliary outputs and dump outputs are placed in the +same directory as the primary output. In auxiliary outputs, the suffix +of the input file is replaced with that of the auxiliary output file +type; in dump outputs, the suffix of the dump file is appended to the +input file suffix. In compilation commands, the base name of both +auxiliary and dump outputs is that of the primary output; in compile and +link commands, the primary output name, minus the executable suffix, is +combined with the input file name. If both share the same base name, +disregarding the suffix, the result of the combination is that base +name, otherwise, they are concatenated, separated by a dash. +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -c foo.c ... +</pre></div> + +<p>will use <samp>foo.o</samp> as the primary output, and place aux outputs and +dumps next to it, e.g., aux file <samp>foo.dwo</samp> for +<samp>-gsplit-dwarf</samp>, and dump file <samp>foo.c.???r.final</samp> for +<samp>-fdump-rtl-final</samp>. +</p> +<p>If a non-linker output file is explicitly specified, aux and dump files +by default take the same base name: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -c foo.c -o dir/foobar.o ... +</pre></div> + +<p>will name aux outputs <samp>dir/foobar.*</samp> and dump outputs +<samp>dir/foobar.c.*</samp>. +</p> +<p>A linker output will instead prefix aux and dump outputs: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c bar.c -o dir/foobar ... +</pre></div> + +<p>will generally name aux outputs <samp>dir/foobar-foo.*</samp> and +<samp>dir/foobar-bar.*</samp>, and dump outputs <samp>dir/foobar-foo.c.*</samp> and +<samp>dir/foobar-bar.c.*</samp>. +</p> +<p>The one exception to the above is when the executable shares the base +name with the single input: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c -o dir/foo ... +</pre></div> + +<p>in which case aux outputs are named <samp>dir/foo.*</samp> and dump outputs +named <samp>dir/foo.c.*</samp>. +</p> +<p>The location and the names of auxiliary and dump outputs can be adjusted +by the options <samp>-dumpbase</samp>, <samp>-dumpbase-ext</samp>, +<samp>-dumpdir</samp>, <samp>-save-temps=cwd</samp>, and +<samp>-save-temps=obj</samp>. +</p> + +<a name="index-dumpbase"></a> +</dd> +<dt><code>-dumpbase <var>dumpbase</var></code></dt> +<dd><p>This option sets the base name for auxiliary and dump output files. It +does not affect the name of the primary output file. Intermediate +outputs, when preserved, are not regarded as primary outputs, but as +auxiliary outputs: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -save-temps -S foo.c +</pre></div> + +<p>saves the (no longer) temporary preprocessed file in <samp>foo.i</samp>, and +then compiles to the (implied) output file <samp>foo.s</samp>, whereas: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -save-temps -dumpbase save-foo -c foo.c +</pre></div> + +<p>preprocesses to in <samp>save-foo.i</samp>, compiles to <samp>save-foo.s</samp> (now +an intermediate, thus auxiliary output), and then assembles to the +(implied) output file <samp>foo.o</samp>. +</p> +<p>Absent this option, dump and aux files take their names from the input +file, or from the (non-linker) output file, if one is explicitly +specified: dump output files (e.g. those requested by <samp>-fdump-*</samp> +options) with the input name suffix, and aux output files (those +requested by other non-dump options, e.g. <code>-save-temps</code>, +<code>-gsplit-dwarf</code>, <code>-fcallgraph-info</code>) without it. +</p> +<p>Similar suffix differentiation of dump and aux outputs can be attained +for explicitly-given <samp>-dumpbase basename.suf</samp> by also specifying +<samp>-dumpbase-ext .suf</samp>. +</p> +<p>If <var>dumpbase</var> is explicitly specified with any directory component, +any <var>dumppfx</var> specification (e.g. <samp>-dumpdir</samp> or +<samp>-save-temps=*</samp>) is ignored, and instead of appending to it, +<var>dumpbase</var> fully overrides it: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c -c -o dir/foo.o -dumpbase alt/foo \ + -dumpdir pfx- -save-temps=cwd ... +</pre></div> + +<p>creates auxiliary and dump outputs named <samp>alt/foo.*</samp>, disregarding +<samp>dir/</samp> in <samp>-o</samp>, the <samp>./</samp> prefix implied by +<samp>-save-temps=cwd</samp>, and <samp>pfx-</samp> in <samp>-dumpdir</samp>. +</p> +<p>When <samp>-dumpbase</samp> is specified in a command that compiles multiple +inputs, or that compiles and then links, it may be combined with +<var>dumppfx</var>, as specified under <samp>-dumpdir</samp>. Then, each input +file is compiled using the combined <var>dumppfx</var>, and default values +for <var>dumpbase</var> and <var>auxdropsuf</var> are computed for each input +file: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c bar.c -c -dumpbase main ... +</pre></div> + +<p>creates <samp>foo.o</samp> and <samp>bar.o</samp> as primary outputs, and avoids +overwriting the auxiliary and dump outputs by using the <var>dumpbase</var> +as a prefix, creating auxiliary and dump outputs named <samp>main-foo.*</samp> +and <samp>main-bar.*</samp>. +</p> +<p>An empty string specified as <var>dumpbase</var> avoids the influence of the +output basename in the naming of auxiliary and dump outputs during +compilation, computing default values : +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -c foo.c -o dir/foobar.o -dumpbase '' ... +</pre></div> + +<p>will name aux outputs <samp>dir/foo.*</samp> and dump outputs +<samp>dir/foo.c.*</samp>. Note how their basenames are taken from the input +name, but the directory still defaults to that of the output. +</p> +<p>The empty-string dumpbase does not prevent the use of the output +basename for outputs during linking: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c bar.c -o dir/foobar -dumpbase '' -flto ... +</pre></div> + +<p>The compilation of the source files will name auxiliary outputs +<samp>dir/foo.*</samp> and <samp>dir/bar.*</samp>, and dump outputs +<samp>dir/foo.c.*</samp> and <samp>dir/bar.c.*</samp>. LTO recompilation during +linking will use <samp>dir/foobar.</samp> as the prefix for dumps and +auxiliary files. +</p> + +<a name="index-dumpbase_002dext"></a> +</dd> +<dt><code>-dumpbase-ext <var>auxdropsuf</var></code></dt> +<dd><p>When forming the name of an auxiliary (but not a dump) output file, drop +trailing <var>auxdropsuf</var> from <var>dumpbase</var> before appending any +suffixes. If not specified, this option defaults to the suffix of a +default <var>dumpbase</var>, i.e., the suffix of the input file when +<samp>-dumpbase</samp> is not present in the command line, or <var>dumpbase</var> +is combined with <var>dumppfx</var>. +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c -c -o dir/foo.o -dumpbase x-foo.c -dumpbase-ext .c ... +</pre></div> + +<p>creates <samp>dir/foo.o</samp> as the main output, and generates auxiliary +outputs in <samp>dir/x-foo.*</samp>, taking the location of the primary +output, and dropping the <samp>.c</samp> suffix from the <var>dumpbase</var>. Dump +outputs retain the suffix: <samp>dir/x-foo.c.*</samp>. +</p> +<p>This option is disregarded if it does not match the suffix of a +specified <var>dumpbase</var>, except as an alternative to the executable +suffix when appending the linker output base name to <var>dumppfx</var>, as +specified below: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c bar.c -o main.out -dumpbase-ext .out ... +</pre></div> + +<p>creates <samp>main.out</samp> as the primary output, and avoids overwriting +the auxiliary and dump outputs by using the executable name minus +<var>auxdropsuf</var> as a prefix, creating auxiliary outputs named +<samp>main-foo.*</samp> and <samp>main-bar.*</samp> and dump outputs named +<samp>main-foo.c.*</samp> and <samp>main-bar.c.*</samp>. +</p> + +<a name="index-dumpdir"></a> +</dd> +<dt><code>-dumpdir <var>dumppfx</var></code></dt> +<dd><p>When forming the name of an auxiliary or dump output file, use +<var>dumppfx</var> as a prefix: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -dumpdir pfx- -c foo.c ... +</pre></div> + +<p>creates <samp>foo.o</samp> as the primary output, and auxiliary outputs named +<samp>pfx-foo.*</samp>, combining the given <var>dumppfx</var> with the default +<var>dumpbase</var> derived from the default primary output, derived in turn +from the input name. Dump outputs also take the input name suffix: +<samp>pfx-foo.c.*</samp>. +</p> +<p>If <var>dumppfx</var> is to be used as a directory name, it must end with a +directory separator: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -dumpdir dir/ -c foo.c -o obj/bar.o ... +</pre></div> + +<p>creates <samp>obj/bar.o</samp> as the primary output, and auxiliary outputs +named <samp>dir/bar.*</samp>, combining the given <var>dumppfx</var> with the +default <var>dumpbase</var> derived from the primary output name. Dump +outputs also take the input name suffix: <samp>dir/bar.c.*</samp>. +</p> +<p>It defaults to the location of the output file, unless the output +file is a special file like <code>/dev/null</code>. Options +<samp>-save-temps=cwd</samp> and <samp>-save-temps=obj</samp> override this +default, just like an explicit <samp>-dumpdir</samp> option. In case +multiple such options are given, the last one prevails: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -dumpdir pfx- -c foo.c -save-temps=obj ... +</pre></div> + +<p>outputs <samp>foo.o</samp>, with auxiliary outputs named <samp>foo.*</samp> because +<samp>-save-temps=*</samp> overrides the <var>dumppfx</var> given by the earlier +<samp>-dumpdir</samp> option. It does not matter that <samp>=obj</samp> is the +default for <samp>-save-temps</samp>, nor that the output directory is +implicitly the current directory. Dump outputs are named +<samp>foo.c.*</samp>. +</p> +<p>When compiling from multiple input files, if <samp>-dumpbase</samp> is +specified, <var>dumpbase</var>, minus a <var>auxdropsuf</var> suffix, and a dash +are appended to (or override, if containing any directory components) an +explicit or defaulted <var>dumppfx</var>, so that each of the multiple +compilations gets differently-named aux and dump outputs. +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c bar.c -c -dumpdir dir/pfx- -dumpbase main ... +</pre></div> + +<p>outputs auxiliary dumps to <samp>dir/pfx-main-foo.*</samp> and +<samp>dir/pfx-main-bar.*</samp>, appending <var>dumpbase</var>- to <var>dumppfx</var>. +Dump outputs retain the input file suffix: <samp>dir/pfx-main-foo.c.*</samp> +and <samp>dir/pfx-main-bar.c.*</samp>, respectively. Contrast with the +single-input compilation: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c -c -dumpdir dir/pfx- -dumpbase main ... +</pre></div> + +<p>that, applying <samp>-dumpbase</samp> to a single source, does not compute +and append a separate <var>dumpbase</var> per input file. Its auxiliary and +dump outputs go in <samp>dir/pfx-main.*</samp>. +</p> +<p>When compiling and then linking from multiple input files, a defaulted +or explicitly specified <var>dumppfx</var> also undergoes the <var>dumpbase</var>- +transformation above (e.g. the compilation of <samp>foo.c</samp> and +<samp>bar.c</samp> above, but without <samp>-c</samp>). If neither +<samp>-dumpdir</samp> nor <samp>-dumpbase</samp> are given, the linker output +base name, minus <var>auxdropsuf</var>, if specified, or the executable +suffix otherwise, plus a dash is appended to the default <var>dumppfx</var> +instead. Note, however, that unlike earlier cases of linking: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c bar.c -dumpdir dir/pfx- -o main ... +</pre></div> + +<p>does not append the output name <samp>main</samp> to <var>dumppfx</var>, because +<samp>-dumpdir</samp> is explicitly specified. The goal is that the +explicitly-specified <var>dumppfx</var> may contain the specified output name +as part of the prefix, if desired; only an explicitly-specified +<samp>-dumpbase</samp> would be combined with it, in order to avoid simply +discarding a meaningful option. +</p> +<p>When compiling and then linking from a single input file, the linker +output base name will only be appended to the default <var>dumppfx</var> as +above if it does not share the base name with the single input file +name. This has been covered in single-input linking cases above, but +not with an explicit <samp>-dumpdir</samp> that inhibits the combination, +even if overridden by <samp>-save-temps=*</samp>: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc foo.c -dumpdir alt/pfx- -o dir/main.exe -save-temps=cwd ... +</pre></div> + +<p>Auxiliary outputs are named <samp>foo.*</samp>, and dump outputs +<samp>foo.c.*</samp>, in the current working directory as ultimately requested +by <samp>-save-temps=cwd</samp>. +</p> +<p>Summing it all up for an intuitive though slightly imprecise data flow: +the primary output name is broken into a directory part and a basename +part; <var>dumppfx</var> is set to the former, unless overridden by +<samp>-dumpdir</samp> or <samp>-save-temps=*</samp>, and <var>dumpbase</var> is set +to the latter, unless overriden by <samp>-dumpbase</samp>. If there are +multiple inputs or linking, this <var>dumpbase</var> may be combined with +<var>dumppfx</var> and taken from each input file. Auxiliary output names +for each input are formed by combining <var>dumppfx</var>, <var>dumpbase</var> +minus suffix, and the auxiliary output suffix; dump output names are +only different in that the suffix from <var>dumpbase</var> is retained. +</p> +<p>When it comes to auxiliary and dump outputs created during LTO +recompilation, a combination of <var>dumppfx</var> and <var>dumpbase</var>, as +given or as derived from the linker output name but not from inputs, +even in cases in which this combination would not otherwise be used as +such, is passed down with a trailing period replacing the compiler-added +dash, if any, as a <samp>-dumpdir</samp> option to <code>lto-wrapper</code>; +being involved in linking, this program does not normally get any +<samp>-dumpbase</samp> and <samp>-dumpbase-ext</samp>, and it ignores them. +</p> +<p>When running sub-compilers, <code>lto-wrapper</code> appends LTO stage +names to the received <var>dumppfx</var>, ensures it contains a directory +component so that it overrides any <samp>-dumpdir</samp>, and passes that as +<samp>-dumpbase</samp> to sub-compilers. +</p> +<a name="index-v"></a> +</dd> +<dt><code>-v</code></dt> +<dd><p>Print (on standard error output) the commands executed to run the stages +of compilation. Also print the version number of the compiler driver +program and of the preprocessor and the compiler proper. +</p> +<a name="index-_0023_0023_0023"></a> +</dd> +<dt><code>-###</code></dt> +<dd><p>Like <samp>-v</samp> except the commands are not executed and arguments +are quoted unless they contain only alphanumeric characters or <code>./-_</code>. +This is useful for shell scripts to capture the driver-generated command lines. +</p> +<a name="index-help"></a> +</dd> +<dt><code>--help</code></dt> +<dd><p>Print (on the standard output) a description of the command-line options +understood by <code>gcc</code>. If the <samp>-v</samp> option is also specified +then <samp>--help</samp> is also passed on to the various processes +invoked by <code>gcc</code>, so that they can display the command-line options +they accept. If the <samp>-Wextra</samp> option has also been specified +(prior to the <samp>--help</samp> option), then command-line options that +have no documentation associated with them are also displayed. +</p> +<a name="index-target_002dhelp"></a> +</dd> +<dt><code>--target-help</code></dt> +<dd><p>Print (on the standard output) a description of target-specific command-line +options for each tool. For some targets extra target-specific +information may also be printed. +</p> +</dd> +<dt><code>--help={<var>class</var><span class="roman">|[</span>^<span class="roman">]</span><var>qualifier</var>}<span class="roman">[</span>,…<span class="roman">]</span></code></dt> +<dd><p>Print (on the standard output) a description of the command-line +options understood by the compiler that fit into all specified classes +and qualifiers. These are the supported classes: +</p> +<dl compact="compact"> +<dt>‘<samp>optimizers</samp>’</dt> +<dd><p>Display all of the optimization options supported by the +compiler. +</p> +</dd> +<dt>‘<samp>warnings</samp>’</dt> +<dd><p>Display all of the options controlling warning messages +produced by the compiler. +</p> +</dd> +<dt>‘<samp>target</samp>’</dt> +<dd><p>Display target-specific options. Unlike the +<samp>--target-help</samp> option however, target-specific options of the +linker and assembler are not displayed. This is because those +tools do not currently support the extended <samp>--help=</samp> syntax. +</p> +</dd> +<dt>‘<samp>params</samp>’</dt> +<dd><p>Display the values recognized by the <samp>--param</samp> +option. +</p> +</dd> +<dt><var>language</var></dt> +<dd><p>Display the options supported for <var>language</var>, where +<var>language</var> is the name of one of the languages supported in this +version of GCC. If an option is supported by all languages, one needs +to select ‘<samp>common</samp>’ class. +</p> +</dd> +<dt>‘<samp>common</samp>’</dt> +<dd><p>Display the options that are common to all languages. +</p></dd> +</dl> + +<p>These are the supported qualifiers: +</p> +<dl compact="compact"> +<dt>‘<samp>undocumented</samp>’</dt> +<dd><p>Display only those options that are undocumented. +</p> +</dd> +<dt>‘<samp>joined</samp>’</dt> +<dd><p>Display options taking an argument that appears after an equal +sign in the same continuous piece of text, such as: +‘<samp>--help=target</samp>’. +</p> +</dd> +<dt>‘<samp>separate</samp>’</dt> +<dd><p>Display options taking an argument that appears as a separate word +following the original option, such as: ‘<samp>-o output-file</samp>’. +</p></dd> +</dl> + +<p>Thus for example to display all the undocumented target-specific +switches supported by the compiler, use: +</p> +<div class="smallexample"> +<pre class="smallexample">--help=target,undocumented +</pre></div> + +<p>The sense of a qualifier can be inverted by prefixing it with the +‘<samp>^</samp>’ character, so for example to display all binary warning +options (i.e., ones that are either on or off and that do not take an +argument) that have a description, use: +</p> +<div class="smallexample"> +<pre class="smallexample">--help=warnings,^joined,^undocumented +</pre></div> + +<p>The argument to <samp>--help=</samp> should not consist solely of inverted +qualifiers. +</p> +<p>Combining several classes is possible, although this usually +restricts the output so much that there is nothing to display. One +case where it does work, however, is when one of the classes is +<var>target</var>. For example, to display all the target-specific +optimization options, use: +</p> +<div class="smallexample"> +<pre class="smallexample">--help=target,optimizers +</pre></div> + +<p>The <samp>--help=</samp> option can be repeated on the command line. Each +successive use displays its requested class of options, skipping +those that have already been displayed. If <samp>--help</samp> is also +specified anywhere on the command line then this takes precedence +over any <samp>--help=</samp> option. +</p> +<p>If the <samp>-Q</samp> option appears on the command line before the +<samp>--help=</samp> option, then the descriptive text displayed by +<samp>--help=</samp> is changed. Instead of describing the displayed +options, an indication is given as to whether the option is enabled, +disabled or set to a specific value (assuming that the compiler +knows this at the point where the <samp>--help=</samp> option is used). +</p> +<p>Here is a truncated example from the ARM port of <code>gcc</code>: +</p> +<div class="smallexample"> +<pre class="smallexample"> % gcc -Q -mabi=2 --help=target -c + The following options are target specific: + -mabi= 2 + -mabort-on-noreturn [disabled] + -mapcs [disabled] +</pre></div> + +<p>The output is sensitive to the effects of previous command-line +options, so for example it is possible to find out which optimizations +are enabled at <samp>-O2</samp> by using: +</p> +<div class="smallexample"> +<pre class="smallexample">-Q -O2 --help=optimizers +</pre></div> + +<p>Alternatively you can discover which binary optimizations are enabled +by <samp>-O3</samp> by using: +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts +gcc -c -Q -O2 --help=optimizers > /tmp/O2-opts +diff /tmp/O2-opts /tmp/O3-opts | grep enabled +</pre></div> + +<a name="index-version"></a> +</dd> +<dt><code>--version</code></dt> +<dd><p>Display the version number and copyrights of the invoked GCC. +</p> +<a name="index-pass_002dexit_002dcodes"></a> +</dd> +<dt><code>-pass-exit-codes</code></dt> +<dd><p>Normally the <code>gcc</code> program exits with the code of 1 if any +phase of the compiler returns a non-success return code. If you specify +<samp>-pass-exit-codes</samp>, the <code>gcc</code> program instead returns with +the numerically highest error produced by any phase returning an error +indication. The C, C++, and Fortran front ends return 4 if an internal +compiler error is encountered. +</p> +<a name="index-pipe"></a> +</dd> +<dt><code>-pipe</code></dt> +<dd><p>Use pipes rather than temporary files for communication between the +various stages of compilation. This fails to work on some systems where +the assembler is unable to read from a pipe; but the GNU assembler has +no trouble. +</p> +<a name="index-specs"></a> +</dd> +<dt><code>-specs=<var>file</var></code></dt> +<dd><p>Process <var>file</var> after the compiler reads in the standard <samp>specs</samp> +file, in order to override the defaults which the <code>gcc</code> driver +program uses when determining what switches to pass to <code>cc1</code>, +<code>cc1plus</code>, <code>as</code>, <code>ld</code>, etc. More than one +<samp>-specs=<var>file</var></samp> can be specified on the command line, and they +are processed in order, from left to right. See <a href="Spec-Files.html#Spec-Files">Spec Files</a>, for +information about the format of the <var>file</var>. +</p> +<a name="index-wrapper"></a> +</dd> +<dt><code>-wrapper</code></dt> +<dd><p>Invoke all subcommands under a wrapper program. The name of the +wrapper program and its parameters are passed as a comma separated +list. +</p> +<div class="smallexample"> +<pre class="smallexample">gcc -c t.c -wrapper gdb,--args +</pre></div> + +<p>This invokes all subprograms of <code>gcc</code> under +‘<samp>gdb --args</samp>’, thus the invocation of <code>cc1</code> is +‘<samp>gdb --args cc1 …</samp>’. +</p> +<a name="index-ffile_002dprefix_002dmap"></a> +</dd> +<dt><code>-ffile-prefix-map=<var>old</var>=<var>new</var></code></dt> +<dd><p>When compiling files residing in directory <samp><var>old</var></samp>, record +any references to them in the result of the compilation as if the +files resided in directory <samp><var>new</var></samp> instead. Specifying this +option is equivalent to specifying all the individual +<samp>-f*-prefix-map</samp> options. This can be used to make reproducible +builds that are location independent. Directories referenced by +directives are not affected by these options. See also +<samp>-fmacro-prefix-map</samp>, <samp>-fdebug-prefix-map</samp>, +<samp>-fprofile-prefix-map</samp> and <samp>-fcanon-prefix-map</samp>. +</p> +<a name="index-fcanon_002dprefix_002dmap"></a> +</dd> +<dt><code>-fcanon-prefix-map</code></dt> +<dd><p>For the <samp>-f*-prefix-map</samp> options normally comparison +of <samp><var>old</var></samp> prefix against the filename that would be normally +referenced in the result of the compilation is done using textual +comparison of the prefixes, or ignoring character case for case insensitive +filesystems and considering slashes and backslashes as equal on DOS based +filesystems. The <samp>-fcanon-prefix-map</samp> causes such comparisons +to be done on canonicalized paths of <samp><var>old</var></samp> +and the referenced filename. +</p> +<a name="index-fplugin"></a> +</dd> +<dt><code>-fplugin=<var>name</var>.so</code></dt> +<dd><p>Load the plugin code in file <var>name</var>.so, assumed to be a +shared object to be dlopen’d by the compiler. The base name of +the shared object file is used to identify the plugin for the +purposes of argument parsing (See +<samp>-fplugin-arg-<var>name</var>-<var>key</var>=<var>value</var></samp> below). +Each plugin should define the callback functions specified in the +Plugins API. +</p> +<a name="index-fplugin_002darg"></a> +</dd> +<dt><code>-fplugin-arg-<var>name</var>-<var>key</var>=<var>value</var></code></dt> +<dd><p>Define an argument called <var>key</var> with a value of <var>value</var> +for the plugin called <var>name</var>. +</p> +<a name="index-fdump_002dada_002dspec"></a> +</dd> +<dt><code>-fdump-ada-spec<span class="roman">[</span>-slim<span class="roman">]</span></code></dt> +<dd><p>For C and C++ source and include files, generate corresponding Ada specs. +See <a href="../gnat_ugn/Generating-Ada-Bindings-for-C-and-C_002b_002b-headers.html#Generating-Ada-Bindings-for-C-and-C_002b_002b-headers">Generating Ada Bindings for C and C++ headers</a> in <cite>GNAT User’s Guide</cite>, which provides detailed documentation on this feature. +</p> +<a name="index-fada_002dspec_002dparent"></a> +</dd> +<dt><code>-fada-spec-parent=<var>unit</var></code></dt> +<dd><p>In conjunction with <samp>-fdump-ada-spec<span class="roman">[</span>-slim<span class="roman">]</span></samp> above, generate +Ada specs as child units of parent <var>unit</var>. +</p> +<a name="index-fdump_002dgo_002dspec"></a> +</dd> +<dt><code>-fdump-go-spec=<var>file</var></code></dt> +<dd><p>For input files in any language, generate corresponding Go +declarations in <var>file</var>. This generates Go <code>const</code>, +<code>type</code>, <code>var</code>, and <code>func</code> declarations which may be a +useful way to start writing a Go interface to code written in some +other language. +</p> + +</dd> +<dt><code>@<var>file</var></code></dt> +<dd><p>Read command-line options from <var>file</var>. The options read are +inserted in place of the original @<var>file</var> option. If <var>file</var> +does not exist, or cannot be read, then the option will be treated +literally, and not removed. +</p> +<p>Options in <var>file</var> are separated by whitespace. A whitespace +character may be included in an option by surrounding the entire +option in either single or double quotes. Any character (including a +backslash) may be included by prefixing the character to be included +with a backslash. The <var>file</var> may itself contain additional +@<var>file</var> options; any such options will be processed recursively. +</p></dd> +</dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Invoking-G_002b_002b.html#Invoking-G_002b_002b" accesskey="n" rel="next">Invoking G++</a>, Previous: <a href="Option-Summary.html#Option-Summary" accesskey="p" rel="previous">Option Summary</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="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |