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description.txt
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/****************** "DHRYSTONE" Benchmark Program ***************************/
#define Version "C, Version 2.2"
/* File: dhry_1.c (part 2 of 3)
* Author: Reinhold P. Weicker
* Siemens Nixdorf, Paderborn/Germany
* Date: May 25, 1988
* Modified: Steven Pemberton, CWI, Amsterdam; [email protected]
* Date: October, 1993; March 1995
* Included both files into one source, that gets compiled
* in two passes. Made program auto-compiling, and auto-running,
* and generally made it much easier to use.
*
* Original Version (in Ada) published in
* "Communications of the ACM" vol. 27., no. 10 (Oct. 1984),
* pp. 1013 - 1030, together with the statistics
* on which the distribution of statements etc. is based.
*
* In this C version, the following C library functions are used:
* - strcpy, strcmp (inside the measurement loop)
* - printf, scanf (outside the measurement loop)
* In addition, Berkeley UNIX system calls "times ()" or "time ()"
* are used for execution time measurement. For measurements
* on other systems, these calls have to be changed.
*
* Collection of Results:
* Reinhold Weicker (address see above) and
*
* Rick Richardson
* PC Research. Inc.
* 94 Apple Orchard Drive
* Tinton Falls, NJ 07724
* Phone: (201) 389-8963 (9-17 EST)
* Usenet: ...!uunet!pcrat!rick
*
* Please send results to Rick Richardson and/or Reinhold Weicker.
* Complete information should be given on hardware and software used.
* Hardware information includes: Machine type, CPU, type and size
* of caches; for microprocessors: clock frequency, memory speed
* (number of wait states).
* Software information includes: Compiler (and runtime library)
* manufacturer and version, compilation switches, OS version.
* The Operating System version may give an indication about the compiler;
* Dhrystone itself performs no OS calls in the measurement loop.
*
* The complete output generated by the program should be mailed
* such that at least some checks for correctness can be made.
*
***************************************************************************
*
* Defines: The following "Defines" are possible:
* -DREG (default: Not defined)
* As an approximation to what an average C programmer
* might do, causes the "register" storage class to be applied
* - for local variables, if they are used (dynamically)
* five or more times
* - for parameters if they are used (dynamically)
* six or more times
* Note that an optimal "register" strategy is
* compiler-dependent, and that "register" declarations
* do not necessarily lead to faster execution.
* -DNOSTRUCTASSIGN (default: Not defined)
* Define if the C compiler does not support
* assignment of structures.
* -DNOENUMS (default: Not defined)
* Define if the C compiler does not support
* enumeration types.
* -DTIMES (default)
* -DTIME
* The "times" function of UNIX (returning process times)
* or the "time" function (returning wallclock time)
* is used for measurement.
* For single user machines, "time ()" is adequate. For
* multi-user machines where you cannot get single-user
* access, use the "times ()" function. If you have
* neither, use a stopwatch in the dead of night.
* "printf"s are provided marking the points "Start Timer"
* and "Stop Timer". DO NOT use the UNIX "time(1)"
* command, as this will measure the total time to
* run this program, which will (erroneously) include
* the time to allocate storage (malloc) and to perform
* the initialization.
* -DHZ=nnn
* In Berkeley UNIX, the function "times" returns process
* time in 1/HZ seconds, with HZ = 60 for most systems.
* CHECK YOUR SYSTEM DESCRIPTION BEFORE YOU JUST APPLY
* A VALUE.
*
***************************************************************************
*
* History: Version C/2.1 was made for two reasons:
*
* 1) There was an obvious need for a common C version of
* Dhrystone, since C is at present the most popular system
* programming language for the class of processors
* (microcomputers, minicomputers) where Dhrystone is used most.
* There should be, as far as possible, only one C version of
* Dhrystone such that results can be compared without
* restrictions. In the past, the C versions distributed
* by Rick Richardson (Version 1.1) and by Reinhold Weicker
* had small (though not significant) differences.
*
* 2) As far as it is possible without changes to the Dhrystone
* statistics, optimizing compilers should be prevented from
* removing significant statements.
*
* This C version has been developed in cooperation with
* Rick Richardson (Tinton Falls, NJ), it incorporates many
* ideas from the "Version 1.1" distributed previously by
* him over the UNIX network Usenet.
* I also thank Chaim Benedelac (National Semiconductor),
* David Ditzel (SUN), Earl Killian and John Mashey (MIPS),
* Alan Smith and Rafael Saavedra-Barrera (UC at Berkeley)
* for their help with comments on earlier versions of the
* benchmark.
*
* Changes: In the initialization part, this version follows mostly
* Rick Richardson's version distributed via Usenet, not the
* version distributed earlier via floppy disk by Reinhold Weicker.
* As a concession to older compilers, names have been made
* unique within the first 8 characters.
* Inside the measurement loop, this version follows the
* version previously distributed by Reinhold Weicker.
*
* At several places in the benchmark, code has been added,
* but within the measurement loop only in branches that
* are not executed. The intention is that optimizing compilers
* should be prevented from moving code out of the measurement
* loop, or from removing code altogether. Since the statements
* that are executed within the measurement loop have NOT been
* changed, the numbers defining the "Dhrystone distribution"
* (distribution of statements, operand types and locality)
* still hold. Except for sophisticated optimizing compilers,
* execution times for this version should be the same as
* for previous versions.
*
* Since it has proven difficult to subtract the time for the
* measurement loop overhead in a correct way, the loop check
* has been made a part of the benchmark. This does have
* an impact - though a very minor one - on the distribution
* statistics which have been updated for this version.
*
* All changes within the measurement loop are described
* and discussed in the companion paper "Rationale for
* Dhrystone version 2".
*
* Because of the self-imposed limitation that the order and
* distribution of the executed statements should not be
* changed, there are still cases where optimizing compilers
* may not generate code for some statements. To a certain
* degree, this is unavoidable for small synthetic benchmarks.
* Users of the benchmark are advised to check code listings
* whether code is generated for all statements of Dhrystone.
*
* Version 2.1 is identical to version 2.0 distributed via
* the UNIX network Usenet in March 1988 except that it corrects
* some minor deficiencies that were found by users of version 2.0.
* The only change within the measurement loop is that a
* non-executed "else" part was added to the "if" statement in
* Func_3, and a non-executed "else" part removed from Proc_3.
*
* Version C/2.2, Steven Pemberton, October 1993
* Functionally, identical to version 2.2; the changes are in
* how you compile and use it:
* - Everything is in one file now, but compiled in 2 passes
* - Compile (and run) by running the file through the shell: 'sh dhry.c"
* - Uses the system definition of HZ if one can be found
* - HZ must be defined, otherwise it won't compile (no defaults here)
* - The (uninteresting) output is printed to stderr (dhry2 > /dev/null)
* - The number of loops is passed as a parameter, rather than read
* (dhry2 500000)
* - If the number of loops is insufficient to get a good result,
* it repeats it with loops*10 until it is enough (rather than just
* stopping)
* - Output says which sort of clock it is using, and the HZ value
* - You can use -DREG instead of the -DREG=register of previous versions
* - Some stylistic cleanups.
*
***************************************************************************
*
* Compilation model and measurement (IMPORTANT):
*
* The following "ground rules" apply for measurements:
* - Separate compilation
* - No procedure merging
* - Otherwise, compiler optimizations are allowed but should be indicated
* - Default results are those without register declarations
* See the companion paper "Rationale for Dhrystone Version 2" for a more
* detailed discussion of these ground rules.
*
* For 16-Bit processors (e.g. 80186, 80286), times for all compilation
* models ("small", "medium", "large" etc.) should be given if possible,
* together with a definition of these models for the compiler system used.
*
**************************************************************************
*
* Dhrystone (C version) statistics:
*
* [Comment from the first distribution, updated for version 2.
* Note that because of language differences, the numbers are slightly
* different from the Ada version.]
*
* The following program contains statements of a high level programming
* language (here: C) in a distribution considered representative:
*
* assignments 52 (51.0 %)
* control statements 33 (32.4 %)
* procedure, function calls 17 (16.7 %)
*
* 103 statements are dynamically executed. The program is balanced with
* respect to the three aspects:
*
* - statement type
* - operand type
* - operand locality
* operand global, local, parameter, or constant.
*
* The combination of these three aspects is balanced only approximately.
*
* 1. Statement Type:
* ----------------- number
*
* V1 = V2 9
* (incl. V1 = F(..)
* V = Constant 12
* Assignment, 7
* with array element
* Assignment, 6
* with record component
* --
* 34 34
*
* X = Y +|-|"&&"|"|" Z 5
* X = Y +|-|"==" Constant 6
* X = X +|- 1 3
* X = Y *|/ Z 2
* X = Expression, 1
* two operators
* X = Expression, 1
* three operators
* --
* 18 18
*
* if .... 14
* with "else" 7
* without "else" 7
* executed 3
* not executed 4
* for ... 7 | counted every time
* while ... 4 | the loop condition
* do ... while 1 | is evaluated
* switch ... 1
* break 1
* declaration with 1
* initialization
* --
* 34 34
*
* P (...) procedure call 11
* user procedure 10
* library procedure 1
* X = F (...)
* function call 6
* user function 5
* library function 1
* --
* 17 17
* ---
* 103
*
* The average number of parameters in procedure or function calls
* is 1.82 (not counting the function values aX *
*
* 2. Operators
* ------------
* number approximate
* percentage
*
* Arithmetic 32 50.8
*
* + 21 33.3
* - 7 11.1
* * 3 4.8
* / (int div) 1 1.6
*
* Comparison 27 42.8
*
* == 9 14.3
* /= 4 6.3
* > 1 1.6
* < 3 4.8
* >= 1 1.6
* <= 9 14.3
*
* Logic 4 6.3
*
* && (AND-THEN) 1 1.6
* | (OR) 1 1.6
* ! (NOT) 2 3.2
*
* -- -----
* 63 100.1
*
*
* 3. Operand Type (counted once per operand reference):
* ---------------
* number approximate
* percentage
*
* Integer 175 72.3 %
* Character 45 18.6 %
* Pointer 12 5.0 %
* String30 6 2.5 %
* Array 2 0.8 %
* Record 2 0.8 %
* --- -------
* 242 100.0 %
*
* When there is an access path leading to the final operand (e.g. a record
* component), only the final data type on the access path is counted.
*
*
* 4. Operand Locality:
* -------------------
* number approximate
* percentage
*
* local variable 114 47.1 %
* global variable 22 9.1 %
* parameter 45 18.6 %
* value 23 9.5 %
* reference 22 9.1 %
* function result 6 2.5 %
* constant 55 22.7 %
* --- -------
* 242 100.0 %
*
* The program does not compute anything meaningful, but it is syntactically
* and semantically correct. All variables have a value assigned to them
* before they are used as a source operand.
*
* There has been no explicit effort to account for the effects of a
* cache, or to balance the use of long or short displacements for code or
* data.
*
***************************************************************************
*/