1LLVM-AR(1) LLVM LLVM-AR(1)
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6 llvm-ar - LLVM archiver
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9 llvm-ar [-]{dmpqrtx}[Rabfikou] [relpos] [count] <archive> [files...]
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12 The llvm-ar command is similar to the common Unix utility, ar. It ar‐
13 chives several files together into a single file. The intent for this
14 is to produce archive libraries by LLVM bitcode that can be linked into
15 an LLVM program. However, the archive can contain any kind of file. By
16 default, llvm-ar generates a symbol table that makes linking faster
17 because only the symbol table needs to be consulted, not each individ‐
18 ual file member of the archive.
19 The llvm-ar command can be used to read SVR4, GNU and BSD style archive
21 files. However, right now it can only write in the GNU format. If an
22 SVR4 or BSD style archive is used with the r (replace) or q (quick
23 update) operations, the archive will be reconstructed in GNU format.
24 Here's where llvm-ar departs from previous ar implementations:
26 Symbol Table
28 Since llvm-ar supports bitcode files. The symbol table it creates is
29 in GNU format and includes both native and bitcode files.
30 Long Paths
32 Currently llvm-ar can read GNU and BSD long file names, but only
33 writes archives with the GNU format.
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36 The options to llvm-ar are compatible with other ar implementations.
37 However, there are a few modifiers (R) that are not found in other ar
38 implementations. The options to llvm-ar specify a single basic opera‐
39 tion to perform on the archive, a variety of modifiers for that opera‐
40 tion, the name of the archive file, and an optional list of file names.
41 These options are used to determine how llvm-ar should process the ar‐
42 chive file.
43 The Operations and Modifiers are explained in the sections below. The
45 minimal set of options is at least one operator and the name of the ar‐
46 chive. Typically archive files end with a .a suffix, but this is not
47 required. Following the archive-name comes a list of files that indi‐
48 cate the specific members of the archive to operate on. If the files
49 option is not specified, it generally means either "none" or "all" mem‐
50 bers, depending on the operation.
51 Operations
53 d
54 Delete files from the archive. No modifiers are applicable to this
55 operation. The files options specify which members should be
56 removed from the archive. It is not an error if a specified file
57 does not appear in the archive. If no files are specified, the ar‐
58 chive is not modified.
59 m[abi]
61 Move files from one location in the archive to another. The a, b,
62 and i modifiers apply to this operation. The files will all be moved
63 to the location given by the modifiers. If no modifiers are used,
64 the files will be moved to the end of the archive. If no files are
65 specified, the archive is not modified.
66 p
68 Print files to the standard output. This operation simply prints the
69 files indicated to the standard output. If no files are specified,
70 the entire archive is printed. Printing bitcode files is
71 ill-advised as they might confuse your terminal settings. The p
72 operation never modifies the archive.
73 q
75 Quickly append files to the end of the archive. This operation
76 quickly adds the files to the archive without checking for dupli‐
77 cates that should be removed first. If no files are specified, the
78 archive is not modified. Because of the way that llvm-ar constructs
79 the archive file, its dubious whether the q operation is any faster
80 than the r operation.
81 r[abu]
83 Replace or insert file members. The a, b, and u modifiers apply to
84 this operation. This operation will replace existing files or insert
85 them at the end of the archive if they do not exist. If no files are
86 specified, the archive is not modified.
87 t[v]
89 Print the table of contents. Without any modifiers, this operation
90 just prints the names of the members to the standard output. With
91 the v modifier, llvm-ar also prints out the file type (B=bitcode,
92 S=symbol table, blank=regular file), the permission mode, the owner
93 and group, the size, and the date. If any files are specified, the
94 listing is only for those files. If no files are specified, the ta‐
95 ble of contents for the whole archive is printed.
96 x[oP]
98 Extract archive members back to files. The o modifier applies to
99 this operation. This operation retrieves the indicated files from
100 the archive and writes them back to the operating system's file sys‐
101 tem. If no files are specified, the entire archive is extract.
102 Modifiers (operation specific)
104 The modifiers below are specific to certain operations. See the Opera‐
105 tions section (above) to determine which modifiers are applicable to
106 which operations.
107 [a]
109 When inserting or moving member files, this option specifies the
110 destination of the new files as being after the relpos member. If
111 relpos is not found, the files are placed at the end of the archive.
112 [b]
114 When inserting or moving member files, this option specifies the
115 destination of the new files as being before the relpos member. If
116 relpos is not found, the files are placed at the end of the archive.
117 This modifier is identical to the i modifier.
118 [i]
120 A synonym for the b option.
121 [o]
123 When extracting files, this option will cause llvm-ar to preserve
124 the original modification times of the files it writes.
125 [u]
127 When replacing existing files in the archive, only replace those
128 files that have a time stamp than the time stamp of the member in
129 the archive.
130 Modifiers (generic)
132 The modifiers below may be applied to any operation.
133 [c]
135 For all operations, llvm-ar will always create the archive if it
136 doesn't exist. Normally, llvm-ar will print a warning message indi‐
137 cating that the archive is being created. Using this modifier turns
138 off that warning.
139 [s]
141 This modifier requests that an archive index (or symbol table) be
142 added to the archive. This is the default mode of operation. The
143 symbol table will contain all the externally visible functions and
144 global variables defined by all the bitcode files in the archive.
145 [S]
147 This modifier is the opposite of the s modifier. It instructs
148 llvm-ar to not build the symbol table. If both s and S are used, the
149 last modifier to occur in the options will prevail.
150 [v]
152 This modifier instructs llvm-ar to be verbose about what it is
153 doing. Each editing operation taken against the archive will produce
154 a line of output saying what is being done.
155
157 The llvm-ar utility is intended to provide a superset of the IEEE Std
158 1003.2 (POSIX.2) functionality for ar. llvm-ar can read both SVR4 and
159 BSD4.4 (or macOS) archives. If the f modifier is given to the x or r
160 operations then llvm-ar will write SVR4 compatible archives. Without
161 this modifier, llvm-ar will write BSD4.4 compatible archives that have
162 long names immediately after the header and indicated using the
163 "#1/ddd" notation for the name in the header.
164
166 The file format for LLVM Archive files is similar to that of BSD 4.4 or
167 macOS archive files. In fact, except for the symbol table, the ar com‐
168 mands on those operating systems should be able to read LLVM archive
169 files. The details of the file format follow.
170 Each archive begins with the archive magic number which is the eight
172 printable characters "!<arch>n" where n represents the newline charac‐
173 ter (0x0A). Following the magic number, the file is composed of even
174 length members that begin with an archive header and end with a n pad‐
175 ding character if necessary (to make the length even). Each file member
176 is composed of a header (defined below), an optional newline-terminated
177 "long file name" and the contents of the file.
178 The fields of the header are described in the items below. All fields
180 of the header contain only ASCII characters, are left justified and are
181 right padded with space characters.
182 name - char[16]
184 This field of the header provides the name of the archive member. If
185 the name is longer than 15 characters or contains a slash (/) char‐
186 acter, then this field contains #1/nnn where nnn provides the length
187 of the name and the #1/ is literal. In this case, the actual name
188 of the file is provided in the nnn bytes immediately following the
189 header. If the name is 15 characters or less, it is contained
190 directly in this field and terminated with a slash (/) character.
191 date - char[12]
193 This field provides the date of modification of the file in the form
194 of a decimal encoded number that provides the number of seconds
195 since the epoch (since 00:00:00 Jan 1, 1970) per Posix specifica‐
196 tions.
197 uid - char[6]
199 This field provides the user id of the file encoded as a decimal
200 ASCII string. This field might not make much sense on non-Unix sys‐
201 tems. On Unix, it is the same value as the st_uid field of the stat
202 structure returned by the stat(2) operating system call.
203 gid - char[6]
205 This field provides the group id of the file encoded as a decimal
206 ASCII string. This field might not make much sense on non-Unix sys‐
207 tems. On Unix, it is the same value as the st_gid field of the stat
208 structure returned by the stat(2) operating system call.
209 mode - char[8]
211 This field provides the access mode of the file encoded as an octal
212 ASCII string. This field might not make much sense on non-Unix sys‐
213 tems. On Unix, it is the same value as the st_mode field of the stat
214 structure returned by the stat(2) operating system call.
215 size - char[10]
217 This field provides the size of the file, in bytes, encoded as a
218 decimal ASCII string.
219 fmag - char[2]
221 This field is the archive file member magic number. Its content is
222 always the two characters back tick (0x60) and newline (0x0A). This
223 provides some measure utility in identifying archive files that have
224 been corrupted.
225 offset - vbr encoded 32-bit integer
227 The offset item provides the offset into the archive file where the
228 bitcode member is stored that is associated with the symbol. The
229 offset value is 0 based at the start of the first "normal" file mem‐
230 ber. To derive the actual file offset of the member, you must add
231 the number of bytes occupied by the file signature (8 bytes) and the
232 symbol tables. The value of this item is encoded using variable bit
233 rate encoding to reduce the size of the symbol table. Variable bit
234 rate encoding uses the high bit (0x80) of each byte to indicate if
235 there are more bytes to follow. The remaining 7 bits in each byte
236 carry bits from the value. The final byte does not have the high bit
237 set.
238 length - vbr encoded 32-bit integer
240 The length item provides the length of the symbol that follows. Like
241 this offset item, the length is variable bit rate encoded.
242 symbol - character array
244 The symbol item provides the text of the symbol that is associated
245 with the offset. The symbol is not terminated by any character. Its
246 length is provided by the length field. Note that is allowed (but
247 unwise) to use non-printing characters (even 0x00) in the symbol.
248 This allows for multiple encodings of symbol names.
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251 If llvm-ar succeeds, it will exit with 0. A usage error, results in an
252 exit code of 1. A hard (file system typically) error results in an exit
253 code of 2. Miscellaneous or unknown errors result in an exit code of 3.
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256 ar(1)
257
259 Maintained by the LLVM Team (https://llvm.org/).
260
262 2003-2020, LLVM Project
2639 2020-08-12 LLVM-AR(1)