cord(1) [osf1 man page]
cord(1) General Commands Manual 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: 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. Displays the version of the cord command. Specifies the output file. If not specified, a.out is used. 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. Specifies the cache size (in bytes) of the machine on which you want to execute. This only affects the -f option. If not speci- fied, 65536 is used. 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 proce- dures 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 gen- erates 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,cor- darg0,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 cord(1)
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cord(1) General Commands Manual cord(1) Name cord - rearranges procedures in an executable to facilitate better cache mapping. Syntax cord [ -c cachesize ] [ -f ] [ -o outfile ] [ -p maxphases ] [ -v ] obj reorder Description The command rearranges procedures in an executable object to maximize efficiency in a machine's cache. By rearranging the procedures prop- erly, the instruction cache miss rate is reduced. The command 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 program which in turn generates a reorder file from a set of profile feedback files (see ). 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 need to be quali- fied x.y where x is the outer procedure). A newline or blank can follow the procedure name: foo.c bar >>i ignore this stuff<< Lines beginning with a pound sign (#) are comments. Lines beginning with a dollar sign ($) are considered directive lines. The only direc- tive 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. Procedures may appear in more than one phase, resulting in more than one copy of it in the final binary. The command will try to relocate references to a procedure to a copy in the requesting phase's list of procedures first and then a random copy if one is not found. You should use the -cord option to a compiler driver like rather than execute cord directly. Options to can be specified with -Wz,cor- darg0,cordarg1,.... If you have to run manually, you should run it once with the driver using the -v flag on a simple program to see the exact passes and their arguments involved in using The obj argument is an executable object with its relocation information intact. This can be achieved by passing the -r -z -d options to the linker, The -r linker option maintains relocation information in the object, but will not make it a ZMAGIC file (hence -z) nor will it allocate common variables (hence -d) as it would without the option. Options -c cachesize Specify the cachesize of the machine you want to execute on in bytes. This only affects the -f option. If not specified 65536 is used. -f Flip the first cachepage size procedures. The assumption when was written was that procedures would be reordered by proce- dure density (cycles/byte). This option ensures that the densest part of each page following the first cachepage would con- flict with least dense part of the first cachepage. -o outputfile specifies the output file. If not specified, a.out is used. -p phasemax Specifies the maximum number of phases allowed. The default is 20. -v Prints verbose information. This includes listing those procedures considered part of other procedures and cannot be rear- ranged (these are basically assembler procedures that may contain relative branches to other procedures rather than relocat- able ones). The listing also list those procedures in the flipped area (if any) and a mapping of old location to new. Restrictions Since 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 don't fit well into one cachepage, performance can degrade. See Also cc(1), ftoc(1), ld(1), prof(1) RISC cord(1)