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hpc-2022-g3/OpenMP/linear-algebra/kernels/atax/atax.c

127 lines
3.4 KiB
C

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <math.h>
/* Include polybench common header. */
#include <polybench.h>
/* Include benchmark-specific header. */
/* Default data type is double, default size is 4000. */
#include "atax.h"
// Workaround for the editor not finding M_PI
// It is exclusive to the GNU C compiler
// https://www.gnu.org/software/libc/manual/html_node/Mathematical-Constants.html
#ifndef M_PI
#define M_PI 3.141
#endif
/* Array initialization. */
static void init_array(int nx, int ny,
DATA_TYPE POLYBENCH_2D(A, NX, NY, nx, ny),
DATA_TYPE POLYBENCH_1D(x, NY, ny))
{
int i, j;
/// Initialize the `x` array with PI and its multiples.
#pragma omp parallel for num_threads(4) schedule(static)
for (i = 0; i < ny; i++) {
x[i] = i * M_PI;
}
// Same here, but many times more
// #pragma omp parallel for num_threads(SOMETHING) schedule(static)
for (i = 0; i < nx; i++)
for (j = 0; j < ny; j++)
A[i][j] = ((DATA_TYPE)i * (j + 1)) / nx;
}
/* DCE code. Must scan the entire live-out data.
Can be used also to check the correctness of the output. */
static void print_array(int nx,
DATA_TYPE POLYBENCH_1D(y, NX, nx))
{
int i;
// Cannot optimize this: prints have to be dependent on each other to make sense!
for (i = 0; i < nx; i++)
{
fprintf(stderr, DATA_PRINTF_MODIFIER, y[i]);
if (i % 20 == 0)
fprintf(stderr, "\n");
}
fprintf(stderr, "\n");
}
/* Main computational kernel. The whole function will be timed,
including the call and return. */
static void kernel_atax(int nx, int ny,
DATA_TYPE POLYBENCH_2D(A, NX, NY, nx, ny),
DATA_TYPE POLYBENCH_1D(x, NY, ny),
DATA_TYPE POLYBENCH_1D(y, NY, ny),
DATA_TYPE POLYBENCH_1D(tmp, NX, nx))
{
int i, j;
// TODO: Optimizable loop, no dependencies
for (i = 0; i < _PB_NY; i++)
y[i] = 0;
// TODO: Optimizable loop, no dependencies
// actually tmp[i] could be a local variable
for (i = 0; i < _PB_NX; i++)
tmp[i] = 0;
// TODO: what do we do here?
for (i = 0; i < _PB_NX; i++)
{
for (j = 0; j < _PB_NY; j++)
tmp[i] = tmp[i] + A[i][j] * x[j];
for (j = 0; j < _PB_NY; j++)
y[j] = y[j] + A[i][j] * tmp[i];
}
}
int main(int argc, char **argv)
{
/* Retrieve problem size. */
int nx = NX;
int ny = NY;
/* Variable declaration/allocation. */
POLYBENCH_2D_ARRAY_DECL(A, DATA_TYPE, NX, NY, nx, ny);
POLYBENCH_1D_ARRAY_DECL(x, DATA_TYPE, NY, ny);
POLYBENCH_1D_ARRAY_DECL(y, DATA_TYPE, NY, ny);
POLYBENCH_1D_ARRAY_DECL(tmp, DATA_TYPE, NX, nx);
/* Initialize array(s). */
init_array(nx, ny, POLYBENCH_ARRAY(A), POLYBENCH_ARRAY(x));
/* Start timer. */
polybench_start_instruments;
/* Run kernel. */
kernel_atax(nx, ny,
POLYBENCH_ARRAY(A),
POLYBENCH_ARRAY(x),
POLYBENCH_ARRAY(y),
POLYBENCH_ARRAY(tmp));
/* Stop and print timer. */
polybench_stop_instruments;
polybench_print_instruments;
/* Prevent dead-code elimination. All live-out data must be printed
by the function call in argument. */
polybench_prevent_dce(print_array(nx, POLYBENCH_ARRAY(y)));
/* Be clean. */
POLYBENCH_FREE_ARRAY(A);
POLYBENCH_FREE_ARRAY(x);
POLYBENCH_FREE_ARRAY(y);
POLYBENCH_FREE_ARRAY(tmp);
return 0;
}