5 llvm-ar - LLVM archiver
9 B<llvm-ar> [-X32_64] [-]{dmpqrtx}[Rabfikouz] [relpos] [count] <archive> [files...]
14 The B<llvm-ar> command is similar to the common Unix utility, C<ar>. It
15 archives several files together into a single file. The intent for this is
16 to produce archive libraries by LLVM bytecode that can be linked into an
17 LLVM program. However, the archive can contain any kind of file. If requested,
18 B<llvm-ar> can generate a symbol table that makes linking faster because
19 only the symbol table needs to be consulted, not each individual file member
22 While the B<llvm-ar> command produces files that are similar to the format
23 used by older C<ar> implementations, it has several significant departures
24 in order to make the archive appropriate for LLVM. Consequently, archives
25 produced with B<llvm-ar> probably won't be readable or editable with any
26 C<ar> implementation unless the archive content is very simple.
28 Here's where B<llvm-ar> departs from previous C<ar> implementations:
34 Since B<llvm-ar> is intended to archive bytecode files, the symbol table
35 won't make much sense to anything but LLVM. Consequently, the symbol table's
36 format has been simplified. It consists simply of a sequence of pairs
37 of a file member index number as an LSB 4byte integer and a null-terminated
42 Some C<ar> implementations (SVR4) use a separate file member to record long
43 path names (> 15 characters). B<llvm-ar> takes the BSD 4.4 and Mac OS X
44 approach which is to simply store the full path name immediately preceding
45 the data for the file. The path name is null terminated and may contain the
50 B<llvm-ar> can compress the members of an archive to save space. The
51 compression used depends on what's available on the platform but favors
52 bzip2 and then zlib. Note that for very small files, bzip2 may increase
53 the file size but generally does about 10% better than zlib on LLVM
56 =item I<Directory Recursion>
58 Most C<ar> implementations do not recurse through directories but simply
59 ignore directories if they are presented to the program in the F<files>
60 option. B<llvm-ar>, however, can recurse through directory structures and
61 add all the files under a directory, if requested.
63 =item I<TOC Verbose Output>
65 When B<llvm-ar> prints out the verbose table of contents (C<tv> option), it
66 precedes the usual output with a character indicating the basic kind of
67 content in the file. A blank means the file is a regular file. A 'Z' means
68 the file is compressed. A 'B' means the file is an LLVM bytecode file. An
69 'S' means the file is the symbol table.
75 The options to B<llvm-ar> are compatible with other C<ar> implementations.
76 However, there are a few modifiers (F<zR>) that are not found in other
77 C<ar>s. The options to B<llvm-ar> specify a single basic operation to
78 perform on the archive, a variety of modifiers for that operation, the
79 name of the archive file, and an optional list of file names. These options
80 are used to determine how B<llvm-ar> should process the archive file.
82 The Operations and Modifiers are explained in the sections below. The minimal
83 set of options is at least one operator and the name of the archive. Typically
84 archive files end with a C<.a> suffix, but this is not required. Following
85 the F<achive-name> comes a list of F<files> that indicate the specific members
86 of the archive to operate on. If the F<files> option is not specified, it
87 generally means either "none" or "all" members, depending on the operation.
95 Delete files from the archive. No modifiers are applicable to this operation.
96 The F<files> options specify which members should be removed from the
97 archive. It is not an error if a specified file does not appear in the archive.
98 If no F<files> are specified, the archive is not modified.
102 Move files from one location in the archive to another. The F<a>, F<b>, and
103 F<i> modifiers apply to this operation. The F<files> will all be moved
104 to the location given by the modifiers. If no modifiers are used, the files
105 will be moved to the end of the archive. If no F<files> are specified, the
106 archive is not modified.
110 Print files to the standard output. The F<k> modifier applies to this
111 operation. This operation simply prints the F<files> indicated to the
112 standard output. If no F<files> are specified, the entire archive is printed.
113 Printing bytecode files is ill-advised as they might confuse your terminal
114 settings. The F<p> operation never modifies the archive.
118 Quickly append files to the end of the archive. The F<R>, F<f>, and F<z>
119 modifiers apply to this operation. This operation quickly adds the
120 F<files> to the archive without checking for duplicates that shoud be
121 removed first. If no F<files> are specified, the archive is not modified.
122 Becasue of the way that B<llvm-ar> constructs the archive file, its dubious
123 whether the F<q> operation is any faster than the F<r> operation.
127 Replace or insert file members. The F<R>, F<a>, F<b>, F<f>, F<u>, and F<z>
128 modifiers apply to this operation. This operation will replace existing
129 F<files> or insert them at the end of the archive if they do not exist. If no
130 F<files> are specified, the archive is not modified.
134 Print the table of contents. Without any modifiers, this operation just prints
135 the names of the members to the standard output. With the F<v> modifier,
136 B<llvm-ar> also prints out the file type (B=bytecode, Z=compressed, S=symbol
137 table, blank=regular file), the permission mode, the owner and group, the
138 size, and the date. If any F<files> are specified, the listing is only for
139 those files. If no F<files> are specified, the table of contents for the
140 whole archive is printed.
144 Extract archive members back to files. The F<o> modifier applies to this
145 operation. This operation retrieves the indicated F<files> from the archive
146 and writes them back to the operating system's file system. If no
147 F<files> are specified, the entire archive is extract.
151 =head2 Modifiers (operation specific)
153 The modifiers below are specific to certain operations. See the Operations
154 section (above) to determine which modifiers are applicable to which operations.
160 When inserting or moving member files, this option specifies the destination of
161 the new files as being C<a>fter the F<relpos> member. If F<relpos> is not found,
162 the files are placed at the end of the archive.
166 When inserting or moving member files, this option specifies the destination of
167 the new files as being C<b>efore the F<relpos> member. If F<relpos> is not
168 found, the files are placed at the end of the archive. This modifier is
169 identical to the the F<i> modifier.
173 Normally, B<llvm-ar> stores the full path name to a file as presented to it on
174 the command line. With this option, truncated (15 characters max) names are
175 used. This ensures name compatibility with older versions of C<ar> but may also
176 thwart correct extraction of the files (duplicates may overwrite). If used with
177 the F<R> option, the directory recursion will be performed but the file names
178 will all be C<f>lattened to simple file names.
182 A synonym for the F<b> option.
186 Normally, B<llvm-ar> will not print the contents of bytecode files when the
187 F<p> operation is used. This modifier defeats the default and allows the
188 bytecode members to be printed.
192 This option is ignored by B<llvm-ar> but provided for compatibility.
196 When extracting files, this option will cause B<llvm-ar> to preserve the
197 original modification times of the files it writes.
201 use full path names when matching
205 This modifier instructions the F<r> option to recursively process directories.
206 Without F<R>, directories are ignored and only those F<files> that refer to
207 files will be added to the archive. When F<R> is used, any directories specified
208 with F<files> will be scanned (recursively) to find files to be added to the
209 archive. Any file whose name begins with a dot will not be added.
213 When replacing existing files in the archive, only replace those files that have
214 a timestamp than the timestamp of the member in the archive.
218 When inserting or replacing any file in the archive, compress the file first.
219 The compression will attempt to use the zlib compression algorithm. This
220 modifier is safe to use when (previously) compressed bytecode files are added to
221 the archive; the compress bytecode files will not be doubly compressed.
225 =head2 Modifiers (generic)
227 The modifiers below may be applied to any operation.
233 For all operations, B<llvm-ar> will always create the archive if it doesn't
234 exist. Normally, B<llvm-ar> will print a warning message indicating that the
235 archive is being created. Using this modifier turns off that warning.
239 This modifier requests that an archive index (or symbol table) be added to the
240 archive. This is the default mode of operation. The symbol table will contain
241 all the externally visible functions and global variables defined by all the
242 bytecode files in the archive. Using this modifer is more efficient that using
243 L<llvm-ranlib|llvm-ranlib> which also creates the symbol table.
247 This modifier is the opposite of the F<s> modifier. It instructs B<llvm-ar> to
248 not build the symbol table. If both F<s> and F<S> are used, the last modifier to
249 occur in the options will prevail.
253 This modifier instructs B<llvm-ar> to be verbose about what it is doing. Each
254 editing operation taken agains the archive will produce a line of output saying
261 The file format for LLVM Archive files is similar to that of BSD 4.4 or Mac OSX
262 archive files. In fact, except for the symbol table, the C<ar> commands on those
263 operating systems should be able to read LLVM archive files. The details of the
266 Each archive begins with the archive magic number which is the eight printable
267 characters !<arch>\n where \n represents the newline character (0x0A). Following
268 the magic number, the file is composed of even length members that begin with an
269 archive header and end with a \n padding character if necessary (to make the
270 length even). Each file member is composed of a header (defined below), an
271 optional null-terminated "long file name" and the contents of the file.
273 The fields of the header are described in the items below. All fields of the
274 header contain only ASCII characters, are left justified and are right padded
275 with space characters.
279 =item name - char[16]
281 This field of the header provides the name of the archive member. If the name is
282 longer than 15 characters or contains a slash (/) character, then this field
283 contains C<#1/nnn> where C<nnn> provides the length of the name and the C<#1/>
284 is literal. In this case, the actual name of the file is provided in the C<nnn>
285 bytes immediately following the header. If the name is 15 characters or less, it
286 is contained directly in this field and terminated with a slash (/) character.
288 =item date - char[12]
290 This field provides the date of modification of the file in the form of a
291 decimal encoded number that provides the number of seconds since the epoch
292 (since 00:00:00 Jan 1, 1970) per Posix specifications.
296 This field provides the user id of the file encoded as a decimal ascii string.
297 This field might not make much sense on non-Unix systems. On Unix, it is the
298 same value as the st_uid field of the stat structure returned by the stat(2)
299 operating system call.
303 This field provides the group id of the file encoded as a decimal ascii string.
304 This field might not make much sense on non-Unix systems. On Unix, it is the
305 same value as the st_gid field of the stat structure returned by the stat(2)
306 operating system call.
310 This field provides the access mode of the file encoded as an octal ascii
311 string. This field might not make much sense on non-Unix systems. On Unix, it
312 is the same value as the st_mode field of the stat structure returned by the
313 stat(2) operating system call.
315 =item size - char[10]
317 This field provides the size of the file, in bytes, encoded as a decimal ascii
318 string. If the size field is negative (starts with a minus sign, 0x02D), then
319 the archive member is stored in compressed form. The first byte of the archive
320 member's data indicates the compression type used. A value of 0 (0x30) indicates
321 that no compression was used. A value of 1 (0x31) indicates that zlib
322 compression was used. A value of 2 (0x32) indicates that bzip2 compression was
327 This field is the archive file member magic number. Its content is always the
328 two characters backtick (0x60) and newline (0x0A). This provides some measure
329 utility in identifying archive files that have been corrupted.
335 If B<llvm-as> succeeds, it will exit with 0. A usage error, results
336 in an exit code of 1. A hard (file system typically) error results in an
337 exit code of 2. Miscellaneous or unknown errors result in an
342 L<llvm-ld|llvm-ld>, L<llvm-ranlib|llvm-ranlib>
346 Maintained by the LLVM Team (L<http://llvm.cs.uiuc.edu>).