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gerrit-public.fairphone.software / toolchain / llvm-project / e4cea8cd3407b93b4ff80ad2db97f16743809008 / . / llvm / docs / CommandGuide / gccld.html
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John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]1<html>
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]2<title>LLVM: gccld tool</title>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]3
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]4<body bgcolor=white>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]5
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]6<center><h1>LLVM: <tt>gccld</tt> tool</h1></center>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]7<HR>
8
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]9<h3>NAME</h3>
10<tt>gccld</tt>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]11
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]12<h3>SYNOPSIS</h3>
13<tt>gccld [options] &lt; filename&gt; [ filename ...]</tt>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]14
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]15<h3>DESCRIPTION</h3>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]16
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]17The <tt>gccld</tt> utility takes a set of LLVM bytecode files and links them
18together into a single LLVM bytecode file. The output bytecode file can be
19another bytecode library or an executable bytecode program. Using additional
20options, <tt>gccld</tt> is able to produce native code executables.
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]21<p>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]22
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]23The <tt>gccld</tt> utility is primarily used by the <a href="llvmgcc.html">C</a>
24and <a href="llvmgxx.html">C++</a> front-ends, and as such, attempts to mimic
25the interface provided by the default system linker so that it can act as a
26"drop-in" replacement.
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]27<p>
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]28
29The <tt>gccld</tt> tool performs a small set of interprocedural, post-link,
30optimizations on the program.
31
32
33<h4>Search Order</h4>
34
35When looking for objects specified on the command line, <tt>gccld</tt> will
36search for the object first in the current directory and then in the directory
37specified by the <tt>LLVM_LIB_SEARCH_PATH</tt> environment variable. If it
38cannot find the object, it fails.
39<p>
40
41When looking for a library specified with the -l option, <tt>gccld</tt> first
42attempts to load a file with that name from the current directory. If that
43fails, it looks for lib&lt;library&gt;.bc, lib&lt;library&gt;.a, or
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]44lib&lt;library&gt;.so, in that order, in each directory added to the library
45search path with the -L option. These directories are searched in order they
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]46were specified. If the library cannot be located, then <tt>gccld</tt> looks in
47the directory specified by the <tt>LLVM_LIB_SEARCH_PATH</tt> environment
48variable. If it does not find lib&lt;library&gt;.[bc | a | so] there, it fails.
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]49
50The -L option is global. It does not matter where it is specified in the list
51of command line arguments; the directory is simply added to the search path and
52is applied to all libraries, preceding or succeeding, in the command line.
53
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]54<h4>Link order</h4>
55
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]56All object files are linked first in the order they were specified on the
57command line. All library files are linked next. Some libraries may not be
58linked into the object program; see below.
59
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]60<h4>Library Linkage</h4>
61
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]62Object files and static bytecode objects are always linked into the output
63file. Library archives (.a files) load only the objects within the archive
64that define symbols needed by the output file. Hence, libraries should be
65listed after the object files and libraries which need them; otherwise, the
66library may not be linked in, and the dependent library will not have its
67undefined symbols defined.
68
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]69<h4>Native code generation</h4>
70
71The <tt>gccld</tt> program has limited support for native code generation, when
72using the -native option.
73
74
75<h3>OPTIONS</h3>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]76
77<ul>
78 <li> -help
79 <br>
80 Print a summary of command line options.
81 <p>
82
83 <li> -o &lt;filename&gt;
84 <br>
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]85 Specify the output filename which will hold the linked bytecode.
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]86 <p>
87
88 <li> -stats
89 <br>
90 Print statistics.
91 <p>
92
93 <li> -time-passes
94 <br>
95 Record the amount of time needed for each pass and print it to standard
96 error.
97 <p>
98
99 <li> -verify
100 <br>
101 Verify each pass result.
102 <p>
103
104 <li> -L=&lt;directory&gt;
105 <br>
106 Add directory to the list of directories to search when looking for
107 libraries.
108 <p>
109
110 <li> -disable-internalize
111 <br>
112 Do not mark all symbols as internal.
113 <p>
114
115 <li> -internalize-public-api-file &lt;filename&gt;
116 <br>
117 Preserve the list of symbol names in the file filename.
118 <p>
119
120 <li> -internalize-public-api-list &lt;list&gt;
121 <br>
122 Preserve the symbol names in list.
123 <p>
124
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]125 <li> -l=&lt;library&gt;
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]126 <br>
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]127 Specify libraries to include when linking the output file. When
128 linking, <tt>gccld</tt> will first attempt to load a file with the
129 pathname library. If that fails, it will then attempt to load
130 lib&lt;library&gt;.bc, lib&lt;library&gt;.a, and lib&lt;library&gt;.so,
131 in that order.
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]132 <p>
133
134 <li> -link-as-library
135 <br>
136 Link the .bc files together as a library, not an executable.
137 <p>
138
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]139 <li> -native
140 <br>
141 Generate a native, machine code executable.
John Criswell67d48112003-09-25 19:14:51 +0000[diff] [blame]142 <p>
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]143 When generating native executables, <tt>gccld</tt> first checks for a bytecode
144 version of the library and links it in, if necessary. If the library is
145 missing, <tt>gccld</tt> skips it. Then, <tt>gccld</tt> links in the same
146 libraries as native code.
John Criswell67d48112003-09-25 19:14:51 +0000[diff] [blame]147 <p>
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]148 In this way, <tt>gccld</tt> should be able to link in optimized bytecode
149 subsets of common libraries and then link in any part of the library that
150 hasn't been converted to bytecode.
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]151 <p>
152
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]153 <li> -s
154 <br>
155 Strip symbol information from the generated executable.
156 <p>
157
158 <li> -v
159 <br>
160 Print information about actions taken.
161</ul>
162
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]163<h3>EXIT STATUS</h3>
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]164
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]165If <tt>gccld</tt> succeeds, it will exit with 0. Otherwise, if an error occurs,
166it will exit with a non-zero value.
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]167
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]168<h3>SEE ALSO</h3>
169<a href="llvm-link.html"><tt>llvm-link</tt></a>
170<a href="gccas.html"><tt>gccas</tt></a>
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]171
Chris Lattnerfc294d12003-10-07 20:01:09 +0000[diff] [blame]172<h3>BUGS</h3>
John Criswellcef81352003-09-25 19:10:25 +0000[diff] [blame]173The -L option cannot be used for find native code libraries when using the
174-native option.
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]175
176<HR>
Chris Lattner7c2b1262003-10-07 20:12:05 +0000[diff] [blame]177Maintained by the <a href="http://llvm.cs.uiuc.edu">LLVM Team</a>.
John Criswell408128d2003-09-11 19:58:03 +0000[diff] [blame]178</body>
179</html>
180