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#include <blitz/timer.h>
using namespace blitz;
void report(const char* name, Timer& timer, int N,
long int iterations);
void unfused(int N);
void fused(int N);
void chunky(int N);
float* _bz_restrict a;
float* _bz_restrict b;
float* _bz_restrict c;
float* _bz_restrict d;
float* _bz_restrict e;
float* _bz_restrict f;
/*
* Code to support the "fuse" macro
*/
int _chunk;
bool _done_chunks;
int _chunk_size = 512;
#define fuse _chunk = 0; _done_chunks = false; \
for (; !_done_chunks; ++_chunk)
int main(int argc, char** argv)
{
if (argc == 2)
_chunk_size = atoi(argv[1]);
cout << "Using chunk size " << _chunk_size << endl;
const int N = 100000;
a = new float[N];
b = new float[N];
c = new float[N];
d = new float[N];
e = new float[N];
f = new float[N];
for (int i=0; i < N; ++i)
{
a[i] = i;
b[i] = i;
c[i] = i;
d[i] = i;
}
Timer timer;
long int iterations = 100;
timer.start();
for (long i=0; i < iterations; ++i)
unfused(N);
timer.stop();
report("Unfused", timer, N, iterations);
timer.start();
for (long i=0; i < iterations; ++i)
fused(N);
timer.stop();
report("Fused", timer, N, iterations);
timer.start();
for (long i=0; i < iterations; ++i)
chunky(N);
timer.stop();
report("Chunky", timer, N, iterations);
return 0;
}
void report(const char* name, Timer& timer, int N,
long int iterations)
{
float flops = float(N) * iterations * 2;
float Mflops = flops / timer.elapsedSeconds() / 1e+6;
cout << setw(20) << name << " " << Mflops << " Mflops/s" << endl;
}
void __sink() { }
void unfused(int N)
{
for (int i=0; i < N; ++i)
e[i] = a[i] * b[i] + c[i] * d[i];
__sink();
for (int i=0; i < N; ++i)
f[i] = c[i] * b[i] + a[i] * d[i];
}
void fused(int N)
{
for (int i=0; i < N; ++i)
{
e[i] = a[i] * b[i] + c[i] * d[i];
f[i] = c[i] * b[i] + a[i] * d[i];
}
}
// This "chunky" routine is a simulated implementation of
// expression templates with tiling across multiple statements
// (the "chunky fusion" approach). This code would be
// generated by:
//
// fuse {
// E = A*B + C*D;
// F = C*B + A*D;
// }
void chunky(int N)
{
fuse {
{ // Code generated by E = A*B + C*D;
int lbound = _chunk * _chunk_size;
int uboundp1 = lbound + _chunk_size;
if (uboundp1 > N)
{
_done_chunks = true;
uboundp1 = N;
}
for (int i=lbound; i < uboundp1; ++i)
e[i] = a[i] * b[i] + c[i] * d[i];
}
__sink();
{ // Code generated by F = C*B + A*D;
int lbound = _chunk * _chunk_size;
int uboundp1 = lbound + _chunk_size;
if (uboundp1 > N)
{
_done_chunks = true;
uboundp1 = N;
}
for (int i=lbound; i < uboundp1; ++i)
f[i] = c[i] * b[i] + a[i] * d[i];
}
}
}
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