Index for Section 1

Alphabetical listing for C

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

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

OPTIONS
  The cord command accepts the following options:

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

  -V  Displays the version of the cord command.

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

  -f  Flips the first cachepage size procedures. When cord was written, the
      assumption 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
      Specifies the cache size (in bytes) of the machine on which you want to
      execute. This only affects the -f option. If not specified, 65536 is
      used.

  -p maxphases
      Specifies the maximum number phases allowed. The default is 20.

DESCRIPTION
  The cord command rearranges procedures in an executable object file to
  maximize efficiency in a machine's cache. By rearranging the procedures
  properly, you can reduce the instruction cache miss rates. The cord command
  does not attempt to determine the correct ordering; it must be 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. The cord options can be specified with
  -Wc,cordarg0,cordarg1,.... If you have to run cord by hand, you may want to
  run it once with the driver using the -v option 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.

SEE ALSO
  Commands:  cc(1), ftoc(1), ld(1), prof(1)

  Programmer's Guide

Index for Section 1

Alphabetical listing for C

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