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NAME

       llvm-ar - LLVM archiver

SYNOPSIS

       llvm-ar [-]{dmpqrtx}[Rabfikouz] [relpos] [count] <archive> [files...]

DESCRIPTION

       The llvm-ar command is similar to the common Unix utility, "ar". It archives several files
       together into a single file. The intent for this is to produce archive libraries by LLVM
       bitcode that can be linked into an LLVM program. However, the archive can contain any kind
       of file. By default, llvm-ar generates a symbol table that makes linking faster because
       only the symbol table needs to be consulted, not each individual file member of the
       archive.

       The llvm-ar command can be used to read both SVR4 and BSD style archive files. However, it
       cannot be used to write them.  While the llvm-ar command produces files that are almost
       identical to the format used by other "ar" implementations, it has two significant
       departures in order to make the archive appropriate for LLVM. The first departure is that
       llvm-ar only uses BSD4.4 style long path names (stored immediately after the header) and
       never contains a string table for long names. The second departure is that the symbol
       table is formated for efficient construction of an in-memory data structure that permits
       rapid (red-black tree) lookups. Consequently, archives produced with llvm-ar usually won't
       be readable or editable with any "ar" implementation or useful for linking.  Using the "f"
       modifier to flatten file names will make the archive readable by other "ar"
       implementations but not for linking because the symbol table format for LLVM is unique. If
       an SVR4 or BSD style archive is used with the "r" (replace) or "q" (quick update)
       operations, the archive will be reconstructed in LLVM format. This means that the string
       table will be dropped (in deference to BSD 4.4 long names) and an LLVM symbol table will
       be added (by default). The system symbol table will be retained.

       Here's where llvm-ar departs from previous "ar" implementations:

       Symbol Table
           Since llvm-ar is intended to archive bitcode files, the symbol table won't make much
           sense to anything but LLVM. Consequently, the symbol table's format has been
           simplified. It consists simply of a sequence of pairs of a file member index number as
           an LSB 4byte integer and a null-terminated string.

       Long Paths
           Some "ar" implementations (SVR4) use a separate file member to record long path names
           (> 15 characters). llvm-ar takes the BSD 4.4 and Mac OS X approach which is to simply
           store the full path name immediately preceding the data for the file. The path name is
           null terminated and may contain the slash (/) character.

       Compression
           llvm-ar can compress the members of an archive to save space. The compression used
           depends on what's available on the platform and what choices the LLVM Compressor
           utility makes. It generally favors bzip2 but will select between "no compression" or
           bzip2 depending on what makes sense for the file's content.

       Directory Recursion
           Most "ar" implementations do not recurse through directories but simply ignore
           directories if they are presented to the program in the files option. llvm-ar,
           however, can recurse through directory structures and add all the files under a
           directory, if requested.

       TOC Verbose Output
           When llvm-ar prints out the verbose table of contents ("tv" option), it precedes the
           usual output with a character indicating the basic kind of content in the file. A
           blank means the file is a regular file. A 'Z' means the file is compressed. A 'B'
           means the file is an LLVM bitcode file. An 'S' means the file is the symbol table.

OPTIONS

       The options to llvm-ar are compatible with other "ar" implementations.  However, there are
       a few modifiers (zR) that are not found in other "ar"s. The options to llvm-ar specify a
       single basic operation to perform on the archive, a variety of modifiers for that
       operation, the name of the archive file, and an optional list of file names. These options
       are used to determine how llvm-ar should process the archive file.

       The Operations and Modifiers are explained in the sections below. The minimal set of
       options is at least one operator and the name of the archive. Typically archive files end
       with a ".a" suffix, but this is not required. Following the archive-name comes a list of
       files that indicate the specific members of the archive to operate on. If the files option
       is not specified, it generally means either "none" or "all" members, depending on the
       operation.

   Operations
       d   Delete files from the archive. No modifiers are applicable to this operation.  The
           files options specify which members should be removed from the archive. It is not an
           error if a specified file does not appear in the archive.  If no files are specified,
           the archive is not modified.

       m[abi]
           Move files from one location in the archive to another. The a, b, and i modifiers
           apply to this operation. The files will all be moved to the location given by the
           modifiers. If no modifiers are used, the files will be moved to the end of the
           archive. If no files are specified, the archive is not modified.

       p[k]
           Print files to the standard output. The k modifier applies to this operation. This
           operation simply prints the files indicated to the standard output. If no files are
           specified, the entire archive is printed.  Printing bitcode files is ill-advised as
           they might confuse your terminal settings. The p operation never modifies the archive.

       q[Rfz]
           Quickly append files to the end of the archive. The R, f, and z modifiers apply to
           this operation.  This operation quickly adds the files to the archive without checking
           for duplicates that should be removed first. If no files are specified, the archive is
           not modified.  Because of the way that llvm-ar constructs the archive file, its
           dubious whether the q operation is any faster than the r operation.

       r[Rabfuz]
           Replace or insert file members. The R, a, b, f, u, and z modifiers apply to this
           operation. This operation will replace existing files or insert them at the end of the
           archive if they do not exist. If no files are specified, the archive is not modified.

       t[v]
           Print the table of contents. Without any modifiers, this operation just prints the
           names of the members to the standard output. With the v modifier, llvm-ar also prints
           out the file type (B=bitcode, Z=compressed, S=symbol table, blank=regular file), the
           permission mode, the owner and group, the size, and the date. If any files are
           specified, the listing is only for those files. If no files are specified, the table
           of contents for the whole archive is printed.

       x[oP]
           Extract archive members back to files. The o modifier applies to this operation. This
           operation retrieves the indicated files from the archive and writes them back to the
           operating system's file system. If no files are specified, the entire archive is
           extract.

   Modifiers (operation specific)
       The modifiers below are specific to certain operations. See the Operations section (above)
       to determine which modifiers are applicable to which operations.

       [a] When inserting or moving member files, this option specifies the destination of the
           new files as being "a"fter the relpos member. If relpos is not found, the files are
           placed at the end of the archive.

       [b] When inserting or moving member files, this option specifies the destination of the
           new files as being "b"efore the relpos member. If relpos is not found, the files are
           placed at the end of the archive. This modifier is identical to the the i modifier.

       [f] Normally, llvm-ar stores the full path name to a file as presented to it on the
           command line. With this option, truncated (15 characters max) names are used. This
           ensures name compatibility with older versions of "ar" but may also thwart correct
           extraction of the files (duplicates may overwrite). If used with the R option, the
           directory recursion will be performed but the file names will all be "f"lattened to
           simple file names.

       [i] A synonym for the b option.

       [k] Normally, llvm-ar will not print the contents of bitcode files when the p operation is
           used. This modifier defeats the default and allows the bitcode members to be printed.

       [N] This option is ignored by llvm-ar but provided for compatibility.

       [o] When extracting files, this option will cause llvm-ar to preserve the original
           modification times of the files it writes.

       [P] use full path names when matching

       [R] This modifier instructions the r option to recursively process directories.  Without
           R, directories are ignored and only those files that refer to files will be added to
           the archive. When R is used, any directories specified with files will be scanned
           (recursively) to find files to be added to the archive. Any file whose name begins
           with a dot will not be added.

       [u] When replacing existing files in the archive, only replace those files that have a
           time stamp than the time stamp of the member in the archive.

       [z] When inserting or replacing any file in the archive, compress the file first.  This
           modifier is safe to use when (previously) compressed bitcode files are added to the
           archive; the compressed bitcode files will not be doubly compressed.

   Modifiers (generic)
       The modifiers below may be applied to any operation.

       [c] For all operations, llvm-ar will always create the archive if it doesn't exist.
           Normally, llvm-ar will print a warning message indicating that the archive is being
           created. Using this modifier turns off that warning.

       [s] This modifier requests that an archive index (or symbol table) be added to the
           archive. This is the default mode of operation. The symbol table will contain all the
           externally visible functions and global variables defined by all the bitcode files in
           the archive. Using this modifier is more efficient that using llvm-ranlib which also
           creates the symbol table.

       [S] This modifier is the opposite of the s modifier. It instructs llvm-ar to not build the
           symbol table. If both s and S are used, the last modifier to occur in the options will
           prevail.

       [v] This modifier instructs llvm-ar to be verbose about what it is doing. Each editing
           operation taken against the archive will produce a line of output saying what is being
           done.

STANDARDS

       The llvm-ar utility is intended to provide a superset of the IEEE Std 1003.2 (POSIX.2)
       functionality for "ar". llvm-ar can read both SVR4 and BSD4.4 (or Mac OS X) archives. If
       the "f" modifier is given to the "x" or "r" operations then llvm-ar will write SVR4
       compatible archives. Without this modifier, llvm-ar will write BSD4.4 compatible archives
       that have long names immediately after the header and indicated using the "#1/ddd"
       notation for the name in the header.

FILE FORMAT

       The file format for LLVM Archive files is similar to that of BSD 4.4 or Mac OSX archive
       files. In fact, except for the symbol table, the "ar" commands on those operating systems
       should be able to read LLVM archive files. The details of the file format follow.

       Each archive begins with the archive magic number which is the eight printable characters
       "!<arch>\n" where \n represents the newline character (0x0A).  Following the magic number,
       the file is composed of even length members that begin with an archive header and end with
       a \n padding character if necessary (to make the length even). Each file member is
       composed of a header (defined below), an optional newline-terminated "long file name" and
       the contents of the file.

       The fields of the header are described in the items below. All fields of the header
       contain only ASCII characters, are left justified and are right padded with space
       characters.

       name - char[16]
           This field of the header provides the name of the archive member. If the name is
           longer than 15 characters or contains a slash (/) character, then this field contains
           "#1/nnn" where "nnn" provides the length of the name and the "#1/" is literal.  In
           this case, the actual name of the file is provided in the "nnn" bytes immediately
           following the header. If the name is 15 characters or less, it is contained directly
           in this field and terminated with a slash (/) character.

       date - char[12]
           This field provides the date of modification of the file in the form of a decimal
           encoded number that provides the number of seconds since the epoch (since 00:00:00 Jan
           1, 1970) per Posix specifications.

       uid - char[6]
           This field provides the user id of the file encoded as a decimal ASCII string.  This
           field might not make much sense on non-Unix systems. On Unix, it is the same value as
           the st_uid field of the stat structure returned by the stat(2) operating system call.

       gid - char[6]
           This field provides the group id of the file encoded as a decimal ASCII string.  This
           field might not make much sense on non-Unix systems. On Unix, it is the same value as
           the st_gid field of the stat structure returned by the stat(2) operating system call.

       mode - char[8]
           This field provides the access mode of the file encoded as an octal ASCII string. This
           field might not make much sense on non-Unix systems. On Unix, it is the same value as
           the st_mode field of the stat structure returned by the stat(2) operating system call.

       size - char[10]
           This field provides the size of the file, in bytes, encoded as a decimal ASCII string.
           If the size field is negative (starts with a minus sign, 0x02D), then the archive
           member is stored in compressed form. The first byte of the archive member's data
           indicates the compression type used. A value of 0 (0x30) indicates that no compression
           was used. A value of 2 (0x32) indicates that bzip2 compression was used.

       fmag - char[2]
           This field is the archive file member magic number. Its content is always the two
           characters back tick (0x60) and newline (0x0A). This provides some measure utility in
           identifying archive files that have been corrupted.

       The LLVM symbol table has the special name "#_LLVM_SYM_TAB_#". It is presumed that no
       regular archive member file will want this name. The LLVM symbol table is simply composed
       of a sequence of triplets: byte offset, length of symbol, and the symbol itself. Symbols
       are not null or newline terminated. Here are the details on each of these items:

       offset - vbr encoded 32-bit integer
           The offset item provides the offset into the archive file where the bitcode member is
           stored that is associated with the symbol. The offset value is 0 based at the start of
           the first "normal" file member. To derive the actual file offset of the member, you
           must add the number of bytes occupied by the file signature (8 bytes) and the symbol
           tables. The value of this item is encoded using variable bit rate encoding to reduce
           the size of the symbol table.  Variable bit rate encoding uses the high bit (0x80) of
           each byte to indicate if there are more bytes to follow. The remaining 7 bits in each
           byte carry bits from the value. The final byte does not have the high bit set.

       length - vbr encoded 32-bit integer
           The length item provides the length of the symbol that follows. Like this offset item,
           the length is variable bit rate encoded.

       symbol - character array
           The symbol item provides the text of the symbol that is associated with the offset.
           The symbol is not terminated by any character. Its length is provided by the length
           field. Note that is allowed (but unwise) to use non-printing characters (even 0x00) in
           the symbol. This allows for multiple encodings of symbol names.

EXIT STATUS

       If llvm-ar succeeds, it will exit with 0.  A usage error, results in an exit code of 1. A
       hard (file system typically) error results in an exit code of 2. Miscellaneous or unknown
       errors result in an exit code of 3.

SEE ALSO

       llvm-ranlib, ar(1)

AUTHORS

       Maintained by the LLVM Team (<http://llvm.org/>).