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poptest.c
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poptest.c
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/* Compare times for popcount instructions */
/* Usage: poptest K N
- measures the time for 1000*N popcount operations on words
with K one bits, comparing with the macro POPCOUNTMAC.
Compile with values for WORDSIZE and POPC with POPC values:
0 = loop, 1 = popcount, 2 = popcountl, 3 = popcountll,
4 = _mm_popcnt_u32, 5 = _mm_popcnt_u32 */
#define MAXN WORDSIZE
#ifndef WORDSIZE
#define WORDSIZE 32
#endif
#ifndef POPC
#error Need a value for POPC
#endif
#include "gtools.h"
#ifdef __INTEL_COMPILER
#include <nmmintrin.h>
#endif
#ifndef POPCOUNTMAC
#define POPCOUNTMAC POPCOUNT
#endif
#if POPC==0
#define NEWPOPC(x,c) {c = 0; while(x){++c; x &= x-1;}}
#endif
#if POPC==1
#define NEWPOPC(x,c) {c = __builtin_popcount(x);}
#endif
#if POPC==2
#define NEWPOPC(x,c) {c = __builtin_popcountl(x);}
#endif
#if POPC==3
#define NEWPOPC(x,c) {c = __builtin_popcountll(x);}
#endif
#if POPC==4
#define NEWPOPC(x,c) {c = _mm_popcnt_u32(x);}
#endif
#if POPC==5
#define NEWPOPC(x,c) {c = _mm_popcnt_u64(x);}
#endif
static setword
ransetword(int k) /* setword with k random bits */
{
register setword w,rb;
register int j;
j = 0;
w = 0;
for (;;)
{
if (j == k) return w;
rb = bit[random() % WORDSIZE];
if ((rb & w) == 0)
{
w |= rb;
++j;
}
}
}
static double
timemac(setword *x, int n, int iters, int *sump)
{
register int c,i,j,sum;
register setword w;
int it;
double t;
sum = 0;
for (i = 0; i < n; ++i)
{
w = x[i];
sum += POPCOUNTMAC(w);
}
t = CPUTIME;
for (it = 0; it < iters; ++it)
{
for (i = 0; i < n; ++i)
{
w = x[i];
sum += POPCOUNTMAC(w);
}
sum ^= it;
}
t = CPUTIME - t;
*sump = sum;
return t;
}
static double
timeold(setword *x, int n, int iters, int *sump)
{
register int c,i,j,sum;
register setword w;
int it;
double t;
sum = 0;
for (i = 0; i < n; ++i)
{
w = x[i];
sum += POPCOUNT(w);
}
t = CPUTIME;
for (it = 0; it < iters; ++it)
{
for (i = 0; i < n; ++i)
{
w = x[i];
sum += POPCOUNT(w);
}
sum ^= it;
}
t = CPUTIME - t;
*sump = sum;
return t;
}
static double
timenew(setword *x, int n, int iters, int *sump)
{
register int c,i,j,sum;
register setword w;
int it;
double t;
sum = 0;
for (i = 0; i < n; ++i)
{
w = x[i];
NEWPOPC(w,c);
sum += c;
}
t = CPUTIME;
for (it = 0; it < iters; ++it)
{
for (i = 0; i < n; ++i)
{
w = x[i];
NEWPOPC(w,c);
sum += c;
}
sum ^= it;
}
t = CPUTIME - t;
*sump = sum;
return t;
}
static double
timenull(setword *x, int n, int iters, int *sump)
{
register int c,i,j,sum;
register setword w;
int it;
double t;
sum = 0;
for (i = 0; i < n; ++i)
{
w = x[i];
NEWPOPC(w,c);
sum += c;
}
t = CPUTIME;
for (it = 0; it < iters; ++it)
{
for (i = 0; i < n; ++i)
{
w = x[i];
c = w;
sum += c;
}
sum ^= it;
}
t = CPUTIME - t;
*sump = sum;
return t;
}
int
main(int argc, char *argv[])
{
int i,k,iters;
setword x[1000];
double tnull,told,tnew,tmac;
int summac,sumold,sumnew,sumnull;
printf("WORDSIZE=%d POPC=%s ",WORDSIZE,
POPC==0 ? "loop" :
POPC==1 ? "popcount" :
POPC==2 ? "popcountl" :
POPC==3 ? "popcountll" :
POPC==4 ? "popcnt_u32" :
POPC==5 ? "popcnt_u64" : "undefined");
#ifdef SETWORD_INT
printf(" setword=unsigned int ");
#endif
#ifdef SETWORD_LONG
printf(" setword=unsigned long ");
#endif
#ifdef SETWORD_LONGLONG
printf(" setword=unsigned long long ");
#endif
#ifdef __SSE4_2__
printf("__SSE4_2__ ");
#endif
#ifdef __POPCNT__
printf("__POPCNT__ ");
#endif
#ifdef __INTEL_COMPILER
printf("__INTEL_COMPILER ");
#endif
printf("\n");
if (argc != 3)
{
fprintf(stderr,"Usage: poptest num1bits numiters\n");
exit(1);
}
k = atoi(argv[1]);
if (k > WORDSIZE) k = WORDSIZE;
iters = atoi(argv[2]);
for (i = 0; i < 1000; ++i)
x[i] = ransetword(k);
tnull = timenull(x,1000,iters,&sumnull);
tmac = timemac(x,1000,iters,&summac);
told = timeold(x,1000,iters,&sumold);
tnew = timenew(x,1000,iters,&sumnew);
if (summac != sumold) printf("*** sum mismatch (mac/old)\n");
if (sumold != sumnew) printf("*** sum mismatch (old/new)\n");
printf("macro=%3.2f compiled=%3.2f new=%3.2f\n",
tmac-tnull,told-tnull,tnew-tnull);
return 0;
}

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