Click this button to go to the index for this section.

cord(1)
NAME
  cord - Rearrange procedures in an executable file to facilitate better
  cache mapping

SYNOPSIS
  cord [-v] [-o outfile] [-f] [-c cachesize] [-p maxphases] obj-file
  reorder-file

DESCRIPTION
  The cord command rearranges procedures in an executable object file to
  maximize efficiency in a machine's cache.  By rearranging the procedures
  properly, we end up reducing the instruction cache miss rates.  cord does
  not attempt to determine the correct ordering, but is given a reorder file
  containing the desired procedure order.  The reorder file is generated by
  the ftoc program, which in turn generates a reorder file from a set of
  profile feedback files (see prof(1)).

  Processed lines in the reorder file are called procedure lines.  Each
  procedure line must be on a separate source line.  Each procedure line must
  contain the source name of the file, followed by a blank followed by a
  qualified procedure name.  Nested procedures must be qualified x.y where x
  is the outer procedure.  A newline or blank can follow the procedure name:

  foo.c bar (everything else following is ignored)


  Lines beginning with # are comments, lines beginning with $ are considered
  cord directive lines. The only directive currently understood is $phase.
  This directive will consider the rest of the file (until the end of file or
  next $phase) as a new phase of the program and will order the procedures
  accordingly.	A procedure may appear in more than one phase, resulting in
  more than one copy of it in the final binary.	 First, cord will try to
  relocate procedure references to a copy of the procedure belonging to the
  requesting phase; otherwise it will relocate the references to a random
  copy.

  Use the -cord option to a compiler driver like cc(1) rather than execute
  cord directly.  cord options can be specified with -
  Wz,cordarg0,cordarg1,....  If you have to run cord by hand, you may want to
  run it once with the driver using the -v flag on a simple program.  This
  will enable you to see the exact passes and the arguments involved in using
  cord.

  WARNING: Since cord works from an input list of procedures generated from
  profile output, the resulting binary is data dependent.  In other words, it
  may only perform well on the same input data that generated the profile
  information, and may perform worse than the original binary on other data.
  Furthermore, if the hot areas in the cache do not fit well into one
  cachepage, performance can degrade.

  The cord command accepts these options:

  -v   Print verbose information.  This includes listing those procedures
       considered part of other procedures and cannot be rearranged (these
       are basically assembler procedures that may contain relative branches
       to other procedures rather than relocatable ones).  The listing also
       lists those procedures in the flipped area (if any) and a mapping of
       old location to new.

  -f   Flip the first cachepage size procedures.  The assumption when cord
       was written was that procedures would be reordered by procedure
       density (cycles/byte).  This option ensures that the densest part of
       each page following the first cachepage would conflict with the
       least-dense part of the first cachepage.

  -c cachesize
       Specify the cachesize (in bytes) of the machine on which you want to
       execute.	 This only affects the -f option.  If not specified, 65536 is
       used.

  -o outputfile
       Specifies the output file. If not specified, a.out is used.

  -p phasemax
       specifies the maximum number phases allowed. The default is 20.

RELATED INFORMATION
  cc(1), ftoc(1), ld(1), prof(1)

  Programmer's Guide