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|
/* ----------------------------------------------------- *
| |
| PC Tech Journal Benchmark Series |
| C Code Optimization Benchmark |
| |
| Copyright (c) 1988 Ziff-Davis Publishing Company |
| |
| This benchmark code is designed to test the |
| code optimization techniques applied by a C |
| compiler. It does not produce meaningful results |
| when executed, or represent good style. |
| |
* ----------------------------------------------------- */
#include <string.h>
#define max_vector 2
#define constant5 5
typedef unsigned char uchar;
int i, j, k , l, m;
int i2, j2, k2;
int g3, h3, i3, k3, m3;
int i4, j4;
int i5, j5, k5;
double flt_1, flt_2, flt_3, flt_4, flt_5, flt_6;
int ivector[ 3 ];
uchar ivector2[ 3 ];
short ivector4[ 6 ];
int ivector5[ 203 ];
#ifndef NO_PROTOTYPES
void dead_code( int, char * );
void unnecessary_loop( void );
void loop_jamming( int );
void loop_unrolling( int );
int jump_compression ( int, int, int, int, int );
#else
void dead_code();
void unnecessary_loop();
void loop_jamming();
void loop_unrolling();
int jump_compression();
#endif
int main( argc, argv ) /* optbench */
int argc;
char **argv;
{
/* ------------------------------ *
| Constant and copy propagation |
* ------------------------------ */
j4 = 2;
if( i2 < j4 && i4 < j4 )
i5 = 2;
j4 = k5;
if( i2 < j4 && i4 < j4 )
i5 = 3;
/* ---------------------------------------- *
| Constant folding, arithmetic identities |
| and redundant load/store operations |
* ---------------------------------------- */
i3 = 1 + 2;
flt_1 = 2.4 + 6.3;
i2 = 5;
j2 = i + 0;
k2 = i / 1;
i4 = i * 1;
i5 = i * 0;
#ifndef NO_ZERO_DIVIDE
/*
* Some compilers correctly recognize a zero divide
* error and do not generate any object code.
*/
/*
i2 = i / 0;
flt_2 = flt_1 / 0.0;
*/
#else
/*
printf( "This compiler handles divide-by-zero as an
error\n");
*/;
#endif
flt_3 = 2.4 / 1.0;
flt_4 = 1.0 + 0.0000001;
flt_5 = flt_6 * 0.0;
flt_6 = flt_2 * flt_3;
/* ------------ *
| Dead store |
* ------------ */
k3 = 1;
k3 = 1;
/* --------------------- *
| Strength reduction |
* --------------------- */
k2 = 4 * j5;
for( i = 0; i <= 5; i++ )
ivector4[ i ] = i * 2;
/* ----------- *
| Simple loop |
* ----------- */
j5 = 0;
k5 = 10000;
do {
k5 = k5 - 1;
j5 = j5 + 1;
i5 = ( k5 * 3 ) / ( j5 * constant5 );
} while ( k5 > 0 );
/* ----------------------------------- *
| Loop induction variable handling |
* ----------------------------------- */
for( i = 0; i < 100; i++)
ivector5[ i * 2 + 3 ] = 5;
/* ----------------------------- *
| Very busy expression handling |
* ----------------------------- */
if( i < 10 )
j5 = i5 + i2;
else
k5 = i5 + i2;
/* -------------------------------------------- *
| Check how the compiler generates the address |
| of a variable with a constant subscript, |
| copy propagation, and register propagation. |
* -------------------------------------------- */
ivector[ 0 ] = 1; /* constant address generation */
ivector[ i2 ] = 2; /* i2 should be a propagated value
*/
ivector[ i2 ] = 2; /* register propagation */
ivector[ 2 ] = 3; /* constant address generation */
/* ---------------------------------- *
| Common subexpression elimination |
* ---------------------------------- */
if(( h3 + k3 ) < 0 || ( h3 + k3 ) > 5 )
/*
printf("Common subexpression elimination\n");
*/;
else {
m3 = ( h3 + k3 ) / i3;
g3 = i3 + (h3 + k3);
}
/* --------------------------------------- *
| Invariant code motion |
| (j * k) can be moved outside the loop. |
* --------------------------------------- */
for( i4 = 0; i4 <= max_vector; i4++ )
ivector2[ i4 ] = j * k;
/* ---------------------------- *
| Function call with arguments |
* ---------------------------- */
dead_code( 1, "This line should not be printed" );
/* ------------------------------- *
| Function call without arguments |
* ------------------------------- */
unnecessary_loop();
exit (0);
} /* end of main */
/* --------------------------------------------- *
| Function: dead_code |
| Test for dead code and dead stores. |
| NO code should be generated. |
* ----------------------------------------------*/
void dead_code( a, b )
int a;
char *b;
{
int idead_store;
idead_store = a;
if( 0 )
/*
printf( "%s\n", b );
*/;
} /* end of dead_code */
/* ----------------------------------------------- *
| Function: unnecessary_loop |
| The loop in the following function is |
| not necessary since the value of the |
| assignment is constant. Ideally, the |
| loop should be optimized out. |
* ----------------------------------------------- */
void unnecessary_loop()
{
int x;
x = 0;
for( i = 0; i < 5; i++ ) /* loop should not be generated */
k5 = x + j5;
} /* end of unnecessary_loop */
/* --------------------------------------------- *
| Function: loop_jamming |
| The two loop in this function share |
| the same loop conditions and could |
| be coalesced together. |
* --------------------------------------------- */
void loop_jamming( x )
int x;
{
for( i = 0; i < 5; i++ )
k5 = x + j5 * i;
for( i = 0; i < 5; i++ )
i5 = x * k5 * i;
} /* end of loop_jamming */
/* ------------------------------------------------ *
| Function: loop_unrolling |
| The loop in this function should be |
| replaced with three inline word stores |
| using constant array arithmetic or by |
| specialized machine instructions used |
| for block memory initializiation. |
* ------------------------------------------------ */
void loop_unrolling( x )
int x;
{
for( i = 0; i < 6; i++ )
ivector4[ i ] = 0;
} /* end of loop_unrolling */
/* ------------------------------------------------------ *
| Function: jump_compression |
| This awkward code is useful to illustrate |
| jump chain compression. The goto 'end_1' can |
| be replaced by a direct jump to 'beg_1'. |
*------------------------------------------------------ */
int jump_compression ( i, j, k, l, m )
int i,j ,l, m;
{
beg_1:
if( i < j )
if( j < k )
if( k < l )
if ( l < m )
l += m;
else
goto end_1;
else
k += l;
else {
j += k;
end_1: goto beg_1;
}
else
i += j;
return( i + j + k + l + m );
} /* end of jump_compression */
|
